Lower-risk Myelodysplastic Syndromes Research Articles

Efficacy and Tolerability of Luspatercept in Patients with Lower Risk Myelodysplastic Syndrome and Anemia: A Systematic Review and Meta-Analysis of Phase III Randomized Controlled Trials

Introduction: Erythropoietin Stimulating Agents (ESAs) are the standard-of-care treatment for most patients with lower risk myelodysplastic syndrome (MDS) and anaemia. However, there has been unmet need for those who failed ESAs other than regular blood transfusion. Luspatercept is a recombinant fusion protein which binds TGF beta ligands resulting in reduction of erythroid maturation through reduction of SMAD2 and SMAD3 signaling. In recent years, studies have shown that luspatercept has significantly improved efficacy in patients with lower risk MDS who failed ESAs with some notable adverse events. The purpose of our meta-analysis is to determine efficacy by observing the rate of transfusion independence for 12 weeks or longer and haematological improvement in erythroid (HIE), and tolerability by rate of treatment emergent serious adverse events (SAE), treatment discontinuation (TD) and treatment interruption (TI) or dose reduction and treatment related mortality in patients with lower risk MDS treated with luspatercept. Methods: We systematically conducted a comprehensive literature search using MEDLINE, EMBASE databases and meeting abstracts from inception through June 30 th, 2023. Phase III RCTs utilizing luspatercept in patients with lower risk MDS that mention efficacy i.e. transfusion independence 12 weeks or longer and HIE and tolerability i.e. rate of treatment discontinuation and interruption, dose reduction, treatment emergent serious adverse events, treatment related mortality were incorporated in the analysis. Mantel-Haenszel (MH) method was used to calculate the estimated pooled risk ratio (RR) with 95% confidence interval (CI). Heterogeneity was assessed with Cochran's Q- statistic. Fixed effects model was applied. Results: 2 phase III RCTs (MEDALIST and COMMANDS) including total 583 patients were eligible in our meta-analysis. MEDALIST trial compared luspatercept vs placebo and COMMANDS trial compared luspatercept vs erythropoietin stimulating agent. The randomization ratios were 2:1 in MEDALIST and 1:1 in COMMANDS trials. Transfusion independence for 12 weeks or longer was noted in 141 (47%) in study arm vs 77 (33.5%) in control arm at RR of 1.67 (95% CI: 1.35 -2.06; P <0.00001). 190 (63.3%) patients in study arm achieved HIE response compared to 88 (38.3%) in control arm at RR of 1.85 (95% CI: 1.53 -2.24; P<0.00001). TD due to TEAE was reported in 21 (6.3%) of luspatercept group vs 10 (4%) in control group with RR of 1.38 (95% CI: 0.67 -2.84; P = 0.39). The incidence for TI or dose reduction due to TEAE was similar between the two groups at 18% with RR of 1.23 (95% CI: 0.88 -1.72; P = 0.22). Treatment emergent SAEs were observed in 116 (35%) in the luspatercept group vs 83 (32.9%) in control group (RR, 1.09; 95% CI: 0.87-1.38; P=0.45). Treatment related mortality was noted in 13 (3.9%) of patients in the study group compared to 16 (6.3%) in the control group with RR of 0.65 (95% CI: 0.31 -1.33; P = 0.24). Conclusions: According to our meta-analysis, luspatercept significantly improved transfusion independent rate and HIE response in patients with lower risk MDS and anaemia compared to control arm. Furthermore, there was no statistically significant difference in the treatment emergent SAEs, treatment discontinuation, treatment interruption or dose reduction and treatment related mortality between the two groups.

Real-World Impact of Luspatercept on Patients with Myelodysplastic Syndromes Requiring Red Blood Cell Transfusions and with Prior Exposure to Erythropoietin-Stimulating Agents: A United States Healthcare Claims Database Study

Background: Myelodysplastic syndromes (MDS) are among the most common hematologic cancers in older US adults. MDS are characterized by abnormal bone marrow function leading to impaired production of blood cells, persistent cytopenia, and variable risk of progression to acute myeloid leukemia (AML). Since anemia is a common complication of MDS, many patients (pts) become dependent on red blood cell transfusions (RBCTs) and erythropoiesis-stimulating agents (ESAs) are the standard of care for patients with lower-risk MDS. In a randomized, double-blind, placebo-controlled phase 3 MEDALIST clinical trial, luspatercept, a first-in-class erythroid maturation agent, was shown to reduce the severity of anemia among transfusion-dependent (TD) pts with lower-risk MDS with ring sideroblasts (RS) status and who were refractory to prior ESA treatment (Fenaux P, et al. N Engl J Med 2020; 382:140-151). However, real-world evidence regarding the effect of luspatercept on transfusion burden among pts with MDS requiring RBCTs and with prior ESA exposure is currently limited. Aim: To describe clinical outcomes and MDS-related treatment patterns before and after the initiation of luspatercept among real-world pts with lower-risk MDS in the USA who required RBCTs before luspatercept initiation and were previously exposed to ESAs. Methods:In this retrospective claims-based cohort study, data from Symphony Health, a nationally representative database, (Jan 1, 2010 to June 30, 2022) were used to identify adults with ≥1 claim with a diagnosis of MDS (initial diagnosis on or after Jan 1, 2015) before the first claim for luspatercept (index date). Pts were considered TD at luspatercept initiation if they had ≥1 claim for RBCT in the 8 weeks before index date, and ESA-exposed if they had ≥1 ESA claim at any point before or at luspatercept initiation. Pts with chemotherapy treatments, with a diagnosis for refractory anemia with excess blasts, or with AML during the study period were excluded as they were presumed to have higher-risk MDS. Pts were also excluded if they had prior use of hypomethylating agents (HMAs) or a diagnosis for β-thalassemia, myelofibrosis, aplastic anemia, or breast cancer in the 6 months prior to index date (baseline period). Pt demographics and clinical characteristics were assessed during the baseline period. Pts' RBCT status (transfusion independent [TI] or TD) was measured in the 6 months after index date. A pt was considered 8-week TI if they had 0 RBCT in ≥1 rolling 8-week period in the 6 months after index date. 12-week, 16-week, and 24-week TI pts were defined similarly, using increasingly longer periods without RBCT. Pts' use of MDS-related treatment classes (ie, chemotherapy, ESAs, granulocyte-colony stimulating factor [G-CSF], HMA, and immunomodulatory imide drug [IMiD] agent) was measured before and after index date until end of data availability or clinical activity (follow-up). Results:The population comprisedof240 pts with MDS who were TD and had ESA exposure before luspatercept initiation. The mean (standard deviation [SD]) age was 75.4 (5.4) years and 56.7% were male. About one fifth of pts received ≥2 treatment classes before luspatercept initiation (2: 17.5%; 3+: 1.7%). Most pts (64.2%) achieved 8-week TI in the 6 months after luspatercept initiation. Similarly, 53.8%, 43.3%, and 29.6% of pts achieved 12-, 16-, and 24-week TI in the 6 months after luspatercept initiation, respectively (Figure 1). The percentage of pts achieving 8-, 12-, 16-, and 24-week TI was numerically higher among pts with positive RS status than those with negative/unknown RS status (Figure 1). Most pts (64.2%) did not require any additional MDS-related treatments during the study follow-up period (mean (SD) 15.6 (7.3) months). The most common treatment classes used after luspatercept initiation were ESA (22.5%) and HMA (16.3%; Figure 2). Conclusions:The findings of this real-world study strongly corroborate clinical trial results, showing that luspatercept is highly effective in reducing transfusion dependence among ESA-exposed pts with lower-risk MDS who were TD before luspatercept initiation. In this study, over half of pts achieved 8-week and 12-week TI status during the follow-up period, and more than a quarter did not require any RBCT over a 24-week period. Further, most pts treated with luspatercept did not require any additional MDS-related treatments during the follow-up period.

Utilization Patterns and Outcomes from Iron Chelation in Elderly Patients with Low-Risk Myelodysplastic Syndrome

Introduction: Iron overload from red blood cell (RBC) transfusions is a source of morbidity and mortality in patients with myelodysplastic syndromes (MDS). Evidence supporting iron chelation therapy (ICT) in Low-Risk MDS (LR-MDS) is controversial on account of studies conducted in highly selected patients and limited clinical trial data. We conducted a large population analysis aimed at defining real-world ICT utilization in LR-MDS and associated outcomes. Methods: We included patients diagnosed with MDS from 2007 to 2017 in SEER-Medicare using ICD-O-3 codes, aged 66 or older, with continuous Medicare parts A, B, and D. Exclusion criteria included patients with high-risk histology (MDS with excess blasts), less than 2-year survival, without complete follow-up, or enrolled in HMO. ICT eligibility was defined as ICD-9/10 codes for transfusion-related iron overload and/or cumulative ≥20 RBC units within ≤2 years of MDS diagnosis. ICT was identified from HCPCS codes for deferoxamine or prescription records for deferasirox or deferiprone. Explanatory variables included age, sex, race, rurality, socioeconomic quintile, marital status, geographic region, MDS histologic subtype, year of diagnosis, Charlson comorbidity index (CCI), and MDS therapies, including erythropoietin-stimulating agents (ESA), hypomethylating agents (HMA), and lenalidomide, identified from HCPCS codes and prescription records. Outcomes were identified through validated algorithms using ICD-9/10 codes and included overall survival (OS), progression to acute myeloid leukemia (AML), and complications related to iron overload, comprising heart failure, non-ischemic heart disease, atrial fibrillation/flutter, and liver disease/cirrhosis. To control for confounding, we implemented 3 approaches: multivariable Cox-proportional hazards regression, propensity score matching (PSM) by conditional probability of receiving ICT, and cause-specific regression with competing risk of death. Results: We analyzed 2,564 LR-MDS patients who were eligible for ICT. The mean ± SD age was 81 ± 6 years and 56.2% were male. Only 393 (15.3%) of these patients received ICT. The initial agent of choice was deferasirox in 203 (51.7%), deferoxamine in 188 (47.8%), and deferiprone in 2 (0.5%). Median ICT duration was 7 months (IQR 1-20). Chelated patients were younger (median age 79 vs 81, p<0.01), more likely to have histology with ringed sideroblasts [RS] (17.8% vs 7%, p<0.01), had less comorbid burden (median CCI 1 vs 2, p<0.01), and were more frequently treated with ESA (42.8% vs 33%, p<0.01), HMA (59% vs 49.8%), and lenalidomide (27% vs 11.1%, p<0.01), than those not treated with ICT. Their median monthly RBC transfusion density was 4 (IQR 2-6). Factors predicting ICT use were histology with RS (OR=1.9, 95%CI 1.4 - 3.8), RBC transfusion density (OR=1.1 per 4 units/month, 95%CI 1.1-1.2), and therapy with ESA (OR=1.5, 95%CI 1.2-1.9), HMA (OR=1.3, 95%CI 1.1-1.8), or lenalidomide (OR=2.6, 95%CI 1.9-3.5). Among patients who received ICT, 352 (89.6%) were considered transfusion dependent (≥2 RBC units within 8 weeks before starting ICT). Of them, 278 (78.9%) achieved hematologic response (≥50% decrease in RBC units following ICT). ICT was associated with decreased risk of death (HR=0.52, 95%CI 0.46-0.59) in the multivariable model adjusting for all listed covariates. The PSM matched 379 chelated (96.4% case rate) with 729 non-chelated patients and yielded similar results for OS benefit from ICT (HR=0.53, 95%CI 0.46-0.61). Table 1 shows results for other outcomes. Across models, ICT was associated with 43-49% decreased risk of AML transformation and 23-32% reduced risk of adverse cardiac outcomes. Cardiac benefit was predominantly driven by a lower risk of heart failure. No significant association was observed between ICT and hepatic outcomes. Conclusions: Our results suggest that ICT is associated with fewer transfusions, improved OS, lower risk of AML, and less adverse cardiac outcomes in LR-MDS. Our older, unselected cohort better reflects real-world LR-MDS patients and builds upon OS benefit reported in more restricting settings. Given the link between clonal hematopoiesis, cardiovascular disease and LR-MDS, defining ICT's effect on molecular and clonal dynamics could clarify the mechanism behind improved cardiac outcomes.

Durable Continuous Transfusion Independence (TI) with Imetelstat in IMerge Phase 3 for Patients with Heavily Transfused Non-Del(5q) Lower-Risk Myelodysplastic Syndromes (LR-MDS) Relapsed/Refractory (R/R) to or Ineligible for Erythropoiesis-Stimulating Agents (ESAs)

CONCLUSIONS MDS are serious life-threatening hematologic malignancies in which a heterogeneous group of clonal disorders results in ineffective hematopoiesis. An unmet need remains for new therapies for patients (pts) with LR-MDS who are red blood cell transfusion dependent (RBC-TD) and R/R to or ineligible for ESAs. Imetelstat, an oligonucleotide, is a first-in-class telomerase inhibitor that targets cells with high telomerase activity by direct binding to the RNA template of telomerase. In the IMerge phase 3 trial, imetelstat produced higher rates of TI for ≥8 weeks, ≥24 weeks, and ≥1 year (39.8%, 28.0%, and 17.8%) than placebo (15.0%, 3.3%, and 1.7%) in pts with non-del(5q) LR-MDS that was RBC-TD, R/R to/ineligible for ESAs, and naïve to lenalidomide or hypomethylating agents (HMAs; Platzbecker et al. EHA 2023. Abstr S165). We report characteristics and clinical benefit for pts with sustained TI for ≥1 year from this trial. IMerge (MDS3001, NCT02598661) is a global, double-blind, randomized, placebo-controlled, phase 3 trial of imetelstat in RBC-TD, ESA-R/R, non-del 5(q) lenalidomide/HMA-naïve LR-MDS. The primary end point was 8-week TI rate; secondary end points included safety, 24-week TI, duration of response, hematologic improvement, and MDS response. Exploratory end points included assessment of cytogenetic response and mutational status with clinical response. The proportion of pts with>1-year TI and other binary end points, were summarized with percentage and 95% 2-sided exact Clopper-Pearson CI. The Kaplan-Meier method was used to estimate the distribution of TI. Of 118 pts receiving imetelstat, 21 (17.8%; 95% CI, 11.4-25.9) achieved ≥1-year sustained TI, representing 45% of ≥8-week TI (21 of 47 pts) and 64% of ≥24-week TI (21 of 33 pts); of 60 pts receiving placebo plus supportive care, 1 (1.7%; 95% CI, 0-8.9) achieved ≥1-year TI. Of the ≥1-year TI imetelstat responders, 15/21 (71.4%) had ring sideroblasts, as did the 1 placebo pt. The median prior RBC transfusion burden was 6 U over 8 weeks (range, 4-9 U) for the imetelstat group and 5 U for the placebo pt. Additional baseline characteristics are in the table. Pts received imetelstat for a median of 101.1 weeks (range, 75.1-163.9 weeks) and a median of 24 cycles (range, 18-41 cycles). The median duration of TI for imetelstat ≥1-year TI responders was 123 weeks (95% CI, 80.4 to not evaluable); the median increase in hemoglobin during the longest TI interval was 5.18 g/dL (range, 2.67-13.76 g/dL) for the imetelstat group vs 1.67 g/dL for the placebo pt. After a median follow-up of 125 weeks, none of the patients with ≥1 year TI on either arm progressed to acute myeloid leukemia (AML). Of the pts receiving imetelstat, 7 had an abnormal karyotype at baseline, of which 6 had reduction in the cytogenetic abnormal clones (4 with cytogenetic complete response and 2 with cytogenetic partial response by independent review committee). Mutation data were available for 18 pts receiving imetelstat, all with SF3B1 mutations present at baseline, and multiple of these pts concurrently had TET2, DNMT3A, ASXL1, or JAK2 mutations. The maximal reduction ranged from −6% to −100% in SF3B1 variant allele frequency (VAF) in these pts, and 13 of 18 (72.2%) achieved ≥50% VAF reduction, including 7 with complete elimination of the VAF. Reduction in other concurrent mutations was also observed in these pts. Safety was consistent with that previously reported; most frequent adverse events were reversible grade 3 or 4 thrombocytopenia and neutropenia. At the time of data cutoff (May 10, 2023), 13 pts receiving imetelstat and the pt receiving placebo were ongoing (Figure); of the 8 who discontinued treatment, 7 had loss of response, and 1 was due to adverse event. Analyses for progression-free and overall survival were not evaluable as of this cutoff date (insufficient follow-up). Treatment with imetelstat resulted in ≥1-year sustained, continuous TI in 17.8% of pts in the IMerge phase 3 trial. In this ESA-R/R/ineligible population with a high prior transfusion burden, a reduction to 0 RBC transfusions for ≥1 year represents an opportunity to achieve relief from iron overload and other transfusion associated complications, and decreased demand on already limited blood product supply. Furthermore, durable TI and meaningful reductions in mutational burden suggest imetelstat may have disease-modifying activity.

Phase 1b/2 Trial of Enasidenib in Lower-Risk MDS and Nonproliferative CMML without Isocitrate Dehydrogenase Type 2 Mutations

Introduction: Enasidenib is an FDA approved selective-inhibitor of mutant IDH2 ( mIDH2) enzyme commonly found in acute myeloid leukemia (AML). Previous studies found enasidenib unexpectedly improved red blood cell and platelet transfusion needs in mIDH2 AML patients without a reduction in AML disease burden (Pollyea DA, et al. Leukemia 2019; 33(11):2575-2584; DiNardo CD, et al. Lancet Oncol 2021; 22(11):1597-1608). We subsequently demonstrated enasidenib robustly enhanced human erythropoiesis from umbilical cord-blood and bone marrow-derived CD34+ hematopoietic progenitor cells independent of IDH2 status and the oncometabolite R-2-hydroxyglutarate (R-2-HG), thus prompting us to investigate enasidenib as an erythropoiesis-stimulating agent (Dutta R, et al. J Clin Invest 2020; 130(4):1843-1849). Aim: To evaluate the safety, tolerability, and efficacy of daily enasidenib in patients with lower-risk MDS or nonproliferative CMML without IDH2 mutations. Methods: In this ongoing two-part phase 1b/2 single-center, investigator-initiated, open-label trial, patients with a diagnosis of IDH2 wildtype lower risk MDS and nonproliferative CMML self-administered continuous daily dosing of enasidenib. Two dose levels were planned at 100mg and 200mg daily for Cohort A and B, respectively based on a standard 3 x 3 dose escalation schema. All patients were evaluated for adverse events (AEs) to determine dose-limiting toxicities (DLTs) and establish the recommended phase 2 dose (RP2D). Patients were screened in a consecutive manner to reduce selection bias by the investigators and all consents were translated into participant's native language to ensure full understanding and voluntary participation. Eligible patients are 18 years or older, ECOG ≤3, negative for IDH2 mutation, have adequate organ function, and symptomatic anemia (hemoglobin <10.5g/dL). Other causes such as iron/nutritional deficiencies and bleeding were ruled out during screening. Prior treatment with ESA, G-CSF, and luspatercept was allowed with a 30-day washout period. Each cycle is 28 days. Patients were evaluated by the PI on Day 1 (±3 days), and laboratory evaluation was conducted every 15 ±3 days. Results: Seven patients were enrolled between July 6, 2022 and December 21, 2022 with three patients in Cohort A receiving 100mg and 4 patients in Cohort B receiving 200mg (Table 1A). No DLTs were seen during the first 6 cycles of treatment. One treatment was discontinued due to the need for treatment of vasculitides related to a new diagnosis of VEXAS made during cycle 2 of the trial (unrelated to study drug). Another patient discontinued treatment after 1 cycle to pursue allogeneic stem cell transplant. All patients experienced at least one treatment-related adverse event (TRAE) which were limited to grade 1 or 2. TRAEs noted were consistent with those previously reported with enasidenib use (Stein EM, et al. Lancet Haematol 2020; 7(4):e309-e319), most commonly hyperbilirubinemia observed in 6 patients (85.7%), nausea in 4 patients (57.1%), and rash (inflammatory dermatoses, previously well-described) in 5 patients (71.4%) (Table 1B) (Parisi R, et al. Leuk Res 2022; 123:106970). No grade 3 or higher TRAE were observed. Two patients (28.7%) experienced a Grade 3 adverse event of pneumonia. Four patients developed an infection (57.1%) with only one requiring a hospitalization. One grade 4 event occurred (duodenal hemorrhage) in a patient with history of duodenal ulcers and concurrent aspirin use. As above, a patient in Cohort A was diagnosed with VEXAS syndrome after enrollment and experienced a complicated course of vasculitis and opportunistic infections in the setting of high dose steroid use. Interestingly, one newly diagnosed patient in the 200mg Cohort B without prior growth factor or ESA is enjoying a sustained trilineage improvement with increase of absolute neutrophil count, hemoglobin, and platelets from baseline (10 cycles at the time of data cutoff of June, 16, 2023). Conclusions: Enasidenib at 200mg dose was safe and well tolerated in patients with lower-risk MDS. Thus far, one patient has seen trilineage improvement in blood counts and continues on study. The Phase 2 portion of the study is ongoing to further characterize safety and evaluate for efficacy to improve anemia and decrease transfusion needs.

Overall Survival in Patients with Ccus Depends on Presence of Anemia

Introduction Clonal cytopenia of undetermined significance (CCUS) is a recently recognized hematological disorder characterized by the presence of one or more cytopenias, evidence of clonal hematopoiesis and not fulfilling the criteria for a myeloid neoplasm. In contrast to myelodysplastic syndromes (MDS) where 95% of the patients are anemic at time of diagnosis, that is only the case for around 60% of patients with CCUS (Weeks et al. Prediction of Risk for Myeloid Malignancy in Clonal Hematopoiesis. NEJM Evid. 2023). Furthermore, as recent studies on survival in CCUS primarily included younger patients (Weeks et al. NEJM Evid. 2023) or population-based cohorts not specifically referred for diagnostic work up of unexplained cytopenia (UC) (Rossi et al. Clinical relevance of clonal hematopoiesis in persons aged ≥80 years, Blood 2021) additional survival data on patients with CCUS are warranted. In this study, we investigated survival outcomes in patients with CCUS referred for primary work up of UC. Methods We included 241 patients with CCUS and compared them to 144 patients with low-risk MDS, defined as having less than 5% blasts in the bone marrow. Bone marrow biopsies and next-generation sequencing (NGS) were performed in all patients and cytogenetic analyses using G-band karyotyping was done in 362 (94%) of cases. For NGS, we used a gene panel with the most commonly mutated genes in MDS. The patients were included at 6 different institutions in Denmark from 2013 and onwards. A cut-point of 5 years follow-up was chosen for more robust survival data, and patients were censored at this time point if followed for more than 5 years. Patients with CCUS were stratified into 3 groups dependent on the type of cytopenia present at diagnosis. CCUS patients with pancytopenia (n = 35), and CCUS patients without pancytopenia were split based on whether they were anemic (n = 143) or not (n =63). We compared overall survival between the CCUS groups and low-risk MDS in a Cox proportional hazards model adjusted for age, sex, number of variants and presence of high-risk variants. Results Of the 241 CCUS patients, 178 (74%) were anemic (hemoglobin < 12 and 13 g/dL for women and men, respectively), while this was the case for 130 (90%) of the patients with MDS. A total of 772 variants were identified in the entire cohort with a median of 2 (IQR: 1-3) per patient for both CCUS and MDS patients. The overall survival at 5 years was 45% for low-risk MDS patients and 62% for CCUS patients. For CCUS patients without anemia, CCUS patients with anemia and CCUS patients with pancytopenia overall survival at 5 years was 85%, 52% and 55%, respectively (p < 0.0001). In the adjusted Cox proportional hazards model, we found a significantly superior overall survival for CCUS patients without anemia compared to those with anemia (HR: 0.28, 95%-CI: 0.13-0.58, p = 0.001) and pancytopenia (HR: 0.22, 95%-CI: 0.09-0.53, p = 0.001) and patients with low-risk MDS (HR: 0.18, 95%-CI: 0.09-0.38, p < 0.001). There was no significant survival difference between CCUS patients with pancytopenia and low-risk MDS patients (HR: 0.67, 95%-CI: 0.46-1.50, p = 0.5). Of the remaining variables, age was the strongest prognostic factor with hazard ratio increasing with a factor 1.05 (95%-CI: 1.03-1.07, p < 0.001) per year aged. Predicted survival probabilities for a 65-year-old and 80-year-old person demonstrate a substantial difference in overall survival across all 3 categories of CCUS (figure 1). Discussion Here we show that the presence of anemia impacts overall survival among CCUS patients. We observe that CCUS patients without anemia, representing 26% of CCUS patients in our cohort, have a superior overall survival compared to those with anemia, even with a comparable mutational profile. Our findings indicate that other factors than mutational signatures impact overall survival. Moreover, the prevalence of CCUS increases with age, and our findings demonstrate a considerable difference in survival between a 65-year-old and 80-year-old person diagnosed with CCUS. This raises the concern that prediction models can overestimate the survival rates if the elderly group of CCUS patients is not well represented in these models. In conclusion, we show that age and hemoglobin levels are important factors in overall survival for CCUS patients, and that patients with CCUS without anemia have a superior overall survival and should be considered as a separate group within the CCUS category.

Red Blood Cell Transfusion Dependence Is Associated with Greater Healthcare Resource Utilization, Higher Medical Cost, and Poorer Prognosis in Patients with Lower-Risk Myelodysplastic Syndromes: A 28-Year Retrospective Observation Study Result

Myelodysplastic syndromes (MDS) encompass a heterogeneous group of myeloid neoplasms characterized by cytopenia due to inefficient hematopoiesis, with a considerable risk of progression to acute myeloid leukemia (AML) or early mortality. In lower-risk MDS (LR-MDS) patients, anemia and its associated complications have been the focus of clinical attention. A significant portion of these patients eventually develop red blood cell transfusion dependence (RBC TD), which has been linked to a poorer prognosis. Given the limited efficacy of available treatments in reducing RBC TD, most patients face increased risks of chronic anemia and various complications. Moreover, RBC TD is known to be associated with reduced overall survival (OS) and leukemia-free survival (LFS). This study aimed to assess the impact of RBC TD on the socioeconomic burden and clinical prognosis of LR-MDS patients, utilizing an electronic medical records (EMR) database spanning nearly 30 years of MDS patient data. This retrospective observational study examined adult MDS patients (≥ 18 years of age) treated at Samsung Medical Center in the Republic of Korea. Eligible patients were diagnosed with MDS between Sep 1, 1994, to Apr 1, 2022 (index period), with the observation period spanning from Sep 1, 1994, to Sep 1, 2022. Baseline assessments included estimation of revised international prognostic scoring system (IPSS-R) scores, categorizing patients with very low, low or intermediate risks as lower-risk MDS (LR-MDS). TD was defined as the occurrence of any 16-week period with RBC transfusion of ≥ 2 units per 8 weeks, without consecutive 56-day period without transfusion. Healthcare resource utilization (HCRU), medical costs, and prognosis indicators including overall survival (OS) and AML-free survival (AFS) were analyzed and compared between patients who experiencing TD and those not (non-TD). Out of 831 MDS patients, 349 (42.0%) were classified as lower-risk at baseline. Among LR-MDS patients, 29.5% (103/349) experienced TD while 23.3% (194/831) experienced TD in the entire study population. The median age at diagnosis of MDS was 63 (ranging from 18 to 89), and 65.3% (543/831) were male. In LR-MDS patients, there were no significant differences in either baseline age (61 vs 63, P=0.16) or gender (71.8% vs 61.0% males, P=0.053) between TD and non-TD groups. However, TD group exhibited significantly higher median erythropoietin (EPO) level than non-TD group (290.5U/L vs. 112U/L, P<0.001) among LR-MDS patients with available baseline serum EPO levels (76 TD and 178 non-TD). Among the 76 TD LR-MDS patients with baseline serum EPO levels, 51 (67.1%) exhibited > 200U/L, which is considered a clinical threshold for erythropoiesis-stimulating agent (ESA) treatment. As shown in Table 1, RBC TD was consistently associated with greater HCRU and higher medical costs, especially in LR-MDS patients. TD LR-MDS patients had higher rates of outpatient department and emergency room visits (15676 vs. 8303 visits and 587 vs. 328 visits per 1000 person-years [PY], respectively), and increased hospitalizations (709 vs. 456 per 1000 PY), with longer hospital stays (13343 vs. 8272 days per 1000 PY). Furthermore, TD LR-MDS patients required over four-times of packed RBC units than non-TD patients (31107 vs. 7073 units per 1000 PY). Consequently, TD LR-MDS patients incurred higher total medical cost than their non-TD counterpart (13.5 million vs. 6.1 million USD per 1000 PY). Median OS (58.4 months vs. 103.1 months) and AFS (52.7 months vs. 102.7 months) were both significantly shorter in the TD group compared to the non-TD group among LR-MDS patients, while the differences in OS and AFS did not reach the level of significance in the entire study population (Table 1 and Figure 1). Notably, median OS after the first documented RBC TD event was 33.8 months (95% confidence interval: 24.7-58.5 months) in LR-MDS patients. The findings of this study indicate that RBC TD can be a strong predictor of increased HCRU and medical costs, as well as decreased OS and AFS over a 20-year period following the initial diagnosis of LR-MDS. Given that a majority of LR-MDS patients experiencing TD may not be eligible for ESA treatment due to elevated EPO levels exceeding 200U/L, and the use of cytotoxic agents is not usually recommended for these patients, these results highlight a substantial unmet need for alternative treatment options to address RBC TD in LR-MDS patients.

Impact of Mutational Status on Clinical Response to Imetelstat in Patients with Lower-Risk Myelodysplastic Syndromes in the IMerge Phase 3 Study

CONCLUSIONS Imetelstat, a first-in-class telomerase inhibitor, showed higher rates of red blood cell (RBC) transfusion independence (TI) for ≥8 weeks, ≥24 weeks, and ≥1 year (39.8%, 28.0%, and 17.8%) than placebo (15.0%, 3.3%, and 1.7%) in the IMerge (NCT02598661) phase 3 study of patients with RBC transfusion-dependent non-del(5q) lower-risk myelodysplastic syndromes (LR-MDS) relapsed/refractory to erythropoiesis-stimulating agents (Platzbecker et al. EHA 2023. Abstr S165). To evaluate the impact of MDS-associated mutations on clinical efficacy of imetelstat, we performed next-generation sequencing of a panel of 36 genes, recurrently mutated in MDS, using DNA samples from peripheral blood collected at study entry. Further analysis of TI responses to imetelstat was performed across different mutation subgroups, defined based on genes involved in different biological functions, including the splicing process, epigenetic modifiers, transcription regulation, and receptors/kinases. Baseline mutation data were available in 165 of 178 patients (imetelstat, n = 110; placebo, n = 55; 93.2% and 91.7% of total in each group, respectively). Of patients with mutation data, 161 (97.6%) had ≥1 mutation detected, among whom, 75 (70.1%), 33 (30.8%), and 9 (8.4%) patients in the imetelstat group and 38 (70.4%), 15 (27.8%), and 7 (13%) patients in the placebo group had >1, >2, and >3 mutations, respectively. The ≥8-week TI rates in the imetelstat vs placebo groups were 42.7% vs 15.8% ( P = .006) for patients with >1 mutation, 45.5% vs 6.7% ( P = .012) for patients with >2 mutations, and 55.6% vs 14.3% ( P = .089) for patients with >3 mutations, respectively. The ≥24-week TI rates were 26.7% vs 2.6% ( P = .003), 33.3% vs 0% ( P = .014), and 33.3% vs 0% ( P = .117), respectively. In patients with mutations associated with poor prognosis ( TP53, ETV6, RUNX1, ASXL1 or EZH2), 31.8% and 9.1% of patients in the imetelstat group achieved ≥8-week and ≥24-week TI vs 0 of those in the placebo group. TP53 mutations were detected in 2 patients in each group; both patients in the imetelstat group and none in the placebo group had ≥8-week TI. Among patients with ASXL1 mutations, 5 of 18 patients (27.8%) in the imetelstat and 0 of 6 (0) in placebo group had ≥8-week TI. Among patients with ETV6 mutations, 1 of 2 (50%) in the imetelstat group and 0 of 1 patients in the placebo group had ≥8-week TI. Two patients in each group had RUNX1 mutations; none achieved TI. Imetelstat ≥8-week TI rates were 43.8%, 37.7%, 40.0%, and 80.0% for patients harboring mutated genes in the RNA spliceosome, epigenetic modifiers, transcription regulation, and receptors/kinases, respectively; ≥24-week TI was 30.2%, 27.5%, 20.0%, and 80.0%, respectively. The most frequently mutated gene was SF3B1 (125 of 165; 75.8%), the ≥8-week and ≥24-week TI rates were 48.8% vs 16.3% ( P = .001) and 35.4% vs 2.3% ( P < .001) with imetelstat vs placebo. In the imetelstat group, ≥8-week TI was achieved in patients with different spectrum of SF3B1 hot-spot mutations: 2 of 8 patients (25.0%) with E622D, 4 of 7 (57.1%) with R625C/L/G, 7 of 12 (58.3%) with H662Q/N/D/Y, 2 of 2 (100%) with T663P, 2 of 6 (33.3%) with K666R/T/Q/N, 18 of 41 (43.9%) with K700E, 2 of 2 (100%) with A744P, and 1 of 2 patients (50.0%) with E783K. Durable ≥24-week TI was also observed in patients with these hot-spot mutations. Other genes with mutation frequency >10% were TET2 (32.7%), DNMT3A (17.0%), ASXL1 (14.5%), and CUX1 (12.7%). The ≥8-week TI rates in the imetelstat group vs placebo group were 50% vs 21.4% for TET2 mutations; 31.6% vs 22.2% for DNMT3A mutations; 27.8% vs 0 for ASXL1 mutations; 35.7% vs 14.3% for CUX1 mutations (Figure). The ≥24-week TI rates were 40% vs 0, 26.3% vs 11.1%, 11.1% vs 0, and 14.3% vs 0, respectively, for those mutations (Figure). Higher RBC-TI rates were observed in patients with various baseline mutational profiles treated with imetelstat compared with placebo in IMerge. While the sample size for specific mutations was small, consistent with the observation that patients with LR-MDS have a low number of specific mutations, TI responses in patients receiving imetelstat occurred regardless of the presence of mutations associated with poor prognosis or the number of mutations. Imetelstat showed comparable TI rates across different molecularly defined subgroups, suggesting that clinical benefit of imetelstat in patients with LR-MDS is independent of the underlying molecular pattern.

Phase 1b Trial of Irak 1/4 Inhibition for Low-Risk Myelodysplastic Syndrome Refractory/Resistant to Prior Therapies: A Trial in Progress

Background and Significance: Chronic stimulation of both the interleukin-1 receptor (IL-1R) and toll-like receptors (TLRs) in myeloid progenitors is thought to promote a proinflammatory environment in the bone marrow that causes persistent cytopenia in patients with low-risk myelodysplastic syndrome (LR-MDS). The serine/threonine kinases IRAK1 and IRAK4 are critical for the signaling downstream of IL-1R and most TLRs that promotes production of proinflammatory cytokines and NLRP3 inflammasome-driven pyroptosis, leading to bone marrow inflammation and cell death. Therefore, inhibition of IRAK1/4 is a potential target for the treatment of LR-MDS by decreasing inflammation and cell death within the bone marrow, allowing for restoration of hematopoiesis. R289 is a prodrug that is converted to the active drug R835 in the gastrointestinal (GI) tract. R835 is a potent and selective inhibitor of IRAK1 and IRAK4 kinases that inhibits TLR and IL-1R-dependent proinflammatory cytokine production in multiple cell types. In vivo, R835 blocks TLR4 and IL-1R-dependent systemic cytokine release in mice. The safety and pharmacokinetic properties of R289/R835 were evaluated in a phase 1 study in healthy volunteers (Study C-906289-001). R289 was well tolerated with no serious or severe adverse events (AEs) reported. Most AEs were mild and transient; the most common AEs (mild/moderate) were headache and GI disturbance. Overall, the phase 1 trial results supported the further study of R289. An open-label phase 1b study to determine the tolerability and preliminary efficacy of R289 for patients with LR-MDS refractory to prior therapies is currently recruiting patients. Study Design and Methods: The R289 phase 1b study (NCT05308264) is an open label, single arm, multi-center study, which includes a dose escalation phase (up to 12 patients) and a dose expansion phase (up to 10 patients). Inclusion criteria for both phases will include patients ≥18 years with a definitive diagnosis of low-risk MDS (International Prognostic Scoring System-R ≤3.5) and ≤5% bone marrow myeloblasts. Patients must be relapsed or refractory/resistant or intolerant to prior MDS therapies. Exclusion criteria include prior MDS treatment(s) within 4 weeks of study treatment, clinically significant anemia (from iron deficiency, hemolysis, or GI bleeding), and chronic myelomonocytic leukemia. Dose Escalation Phase: A 3+3 dose escalation design will be used to determine the maximum tolerated dose (MTD). An initial R289 dose of 250 mg qd, will be given orally, with or without food, progressing to 500 mg qd with dose limiting toxicity (DLT) assessed at both doses. The DLT evaluation period will be 28 days. After completion, patients not experiencing DLTs may remain at their respective dose levels as long as they demonstrate continued clinical benefit without toxicity. Dose Expansion Phase: Up to 10 additional patients with LR-MDS will be enrolled, with R289 administered to all patients at a dose not exceeding the MTD determined in the dose escalation phase. The primary endpoint of the study is safety and tolerability of R289, assessed by incidence of AEs, discontinuation/interruption of R289 due to AEs, and incidence of DLTs. Secondary endpoints include preliminary efficacy, assessed by red blood cell transfusion independence by Week 24 (% achieving ≥50% reduction in transfusions), and pharmacokinetics of R289. Change from baseline in plasma biomarkers, including C-reactive protein and TNFα, and bone marrow biomarkers will be assessed. Statistical analyses will be primarily descriptive. Tabulations will be produced for disposition, demographics, disease characteristics, safety, pharmacokinetics, pharmacodynamics, and clinical activity. For analyses of clinical activity, such as proportion of patients with RBC transfusion independence, complete responder rate, overall response rate, and proportion of subjects with hematologic improvements, the summary will be produced separately for the dose escalation phase and dose expansion phase. For the dose escalation phase, data will be summarized by dose level and overall. The trial is currently recruiting at 9 US sites. The study has enrolled 7 patients in the dose escalation phase.

Improved Overall Survival Among Luspatercept Responders and Predictors of Response

Introduction Luspatercept (luspa) is a first-in-class erythroid-maturation agent approved for red blood cells transfusion dependent (RBC-TD) lower risk myelodysplastic syndrome (LR-MDS) with ring sideroblast (RS) based on MEDALIST clinical trial. We aimed to explore impact of luspa on overall survival (OS) and predictors of response in a large cohort of pts treated with luspa, collected from Moffitt Cancer Center (MCC) and from Fondazione Italiana Sindromi Mielodisplastiche (FISiM). Methods We evaluated all pts with LR-MDS-RS treated with luspa from MCC cohort since FDA approval, and from a multicenter observational trial of FISiM for pts treated on a compassionate use program . Baseline RBC transfusion burden (TB) was defined as: non-transfusion dependent (NTD) (0 units in 8 weeks prior luspa), low TB (LTB) (1-5 units/8 weeks ) and high TB (HTB) (≥ 6 units/8 weeks). A hematological response (HI) was defined as an (i) objective Hgb increase of > 1.5 g/dl in NTD, and (ii) RBC-TI with Hgb increase of 1.5 g/dl, or RBC-TI without Hgb 1.5 g/dl increase, or >50% reduction in RBC TB among RBC-TD. Somatic mutation (MT) data were available for 137 pts. Results Between January 2020 and March 2023, 331 pts were treated with Luspa (Table-1). The median age was 69 years; 308 pts (93%) had MDS-RS, 86,1% were intermediate, low or very low risk MDS by R-IPSS and 82% (105/128) were moderate low (ML), low (L) or very low (VL) by IPPS-M. SF3B1 MT was detected in 86.3% (120/139) with a median VAF of 37.7. The mean Hgb level was 7.97 g/dl and 93.7% were RBC-TD. Majority had prior erythroid stimulating agents (ESA) (93.6%). In the MCC cohort 42.9% (52/121) had prior hypomethylating agents (HMA) therapy, and 31.4% (38/121) had prior lenalidomide (len). With a median follow up of 14.6 mos from starting luspa treatment, the median OS was not reached (NR) among responders to luspa compared to 24.5 mos for non-responders (p <.001) (Figure-1). The median OS benefit was more pronounced among pts with RBC-TI and Hgb> 1.5 g/dl increase compared to other categories of response. In the NTD group at baseline, the median OS among luspa responders was NR compared to 22.7 mos among non-responders (P< .001). In the LTB group at baseline median OS was NR as well among luspa responders compared to 29.9 mos in non-responders (p=.002) and finally among HTB group at baseline, the median OS among luspa responders was 35.4 mos compared to 21.2 mos in non-responders (p=.007). In multivariable analysis adjusting for IPSS-M and baseline RBC-TD, response to luspa was independently associated with improved OS, HR .39 (95% CI .18-.83), p= .015 The overall HI rate to luspa was 40.6% (134/330) (Table-1), 85% of pts needed dose escalation, HI correlated with baseline RBC-TB where 80% (16/20) NTD, 60.2% (65/108) LTB and 41.8% HTB (77/184) achieved HI respectively, p< .001. By IPSS-M, there was a trend for lower HI with higher risk disease (100% in VL, 60.3% in L, 36.7% in ML, 56.3% in MH, 16.7% in H risk pts, p=.051). There was a mild trend for higher response among SF3B1 MT pts compared to wild type, 54% (64/119) versus 42% (8/19), p=.34.The segregation of SF3B1 MT cases into three independent groups based on IPSS-M, showed that HI rate was better in SF3B1 β ( SF3B1 and any gene from BCOR, BCORL1, NRAS, RUNX1, SRSF2 or STAG2) and SF3B1 α (as any other mutant) than SF3B1 5q(concomitantpresence with isolated del5q): 50% (7/14), 58.8% (57/97), and 0% (0/5) respectively, p=.03. Among SF3B1 5qpts, 4 had been treated with len before luspa and only 1 had achieved an HI with prior len. Among pts with SF3B1 MT, we observed a trend for higher response in pts with the hotspot K700E, 62.7% (37/59) vs 47.4% (27/57) in non-K700E, p=.097. In pts with SF3B1 MT, divided by median VAF, we observed a trend for better HI with VAF was >38, 63.5% (33/52) vs 45.3% (24/53), p=.062. Among responders, the median duration of response was 14.1 mos. As of last follow up, 85% pts (191/224) discontinued treatment. Reason of discontinuation was lack of response in 126 pts, loss of response in 26 patients and adverse events in 6 pts. The most common reported adverse events were fatigue (n=10), GI symptoms (n=4), shortness of breath and arthralgia (1 each). Conclusions Our RWD in the largest luspa treated cohort demonstrates OS benefit to luspa response. Low baseline RBC-TB dependency, lower risk IPSS-M, SF3B1 MT, SF3B1-K700E mutation and SF3B1 α co-mutations correlated with higher response rates. Our data emphasizes the impact of RBC-TI in LR-MDS.

Characterization and Management of Cytopenias after Imetelstat Treatment in the IMerge Phase 3 Trial of Patients with Lower-Risk Myelodysplastic Syndromes (LR-MDS)

CONCLUSIONS Imetelstat, an oligonucleotide and a first-in-class telomerase inhibitor, selectively targets malignant hematopoietic stem and progenitor cells with high telomerase activity by direct binding to the RNA template. In patients with MDS the on-target effects of imetelstat are associated with the development of hematologic treatment-emergent adverse events (TEAEs). In the IMerge phase 3 trial, among patients treated with imetelstat, 68% experienced grade 3-4 neutropenia, and 62% had grade 3-4 thrombocytopenia; however, clinical consequences of grade 3-4 infection or bleeding were similar in patients treated with imetelstat and placebo (Platzbecker et al. EHA 2023. Abstr S165). Here, we report additional data on the occurrence and management of cytopenias after treatment with imetelstat. IMerge phase 3 trial (NCT02598661) is a multicenter study involving 178 patients with a median age of 72 years with red blood cell (RBC) transfusion dependency and LR-MDS relapsed/refractory to or ineligible for erythropoiesis-stimulating agents. Patients were randomized 2:1 to receive either imetelstat or placebo and stratified by prior RBC transfusion burden (4-6 or >6 U) and by International Prognostic Scoring System risk group. The safety population included all patients who received ≥1 dose of study drug and comprised 118 patients treated with imetelstat and 59 with placebo. TEAEs of neutropenia and thrombocytopenia with imetelstat treatment were more prevalent in cycles 1-3 (68.6% and 62.7% respectively), and their frequency decreased over time: 42.7% and 48.5% in cycles 4-6, 36.8% and 44.7% in cycles 7-12, and 31.3% and 37.5% in cycle 13 and beyond. Based on laboratory assessment, neutrophil and platelet counts decreased from baseline levels in patients treated with imetelstat versus those treated with placebo (91.5% and 95.8% vs 47.5% and 33.9%, respectively). Neutropenia decreased to a maximum of grade 4 and 3 in 55 and 29 of imetelstat-treated patients, respectively, and >80% of cytopenia events stabilized to grade ≤2 within 4 weeks (Figure). The median time to grade 4 neutropenia was 5.0 weeks (range,1.1-90.3 weeks) for the imetelstat group vs 23.0 weeks (range, 23.0-23.0 weeks) for the placebo group. Similarly, median time to grade 4 thrombocytopenia was 5.2 weeks (range, 2.0-29.9 weeks) with imetelstat vs 35.5 weeks (range, 28.0-43.0 weeks) with placebo. It is noteworthy that among 47 patients who achieved the primary end point of 8-week RBC transfusion independence with imetelstat, 34 (72.3%) and 28 patients (59.6%) had grade 3-4 neutropenia and grade 3-4 thrombocytopenia, respectively. In the imetelstat group, 3 patients had grade 3-4 neutropenia concurrent with grade 3-4 infections, and no patients experienced grade 3-4 thrombocytopenia associated with grade 3-4 bleeding events. There were no grade 5 cytopenias for either imetelstat or placebo groups. In the imetelstat group, cytopenias were managed with protocol-specified treatment delays and dose adjustments. Dose reductions due to neutropenia and thrombocytopenia occurred in 39 patients (33.1%) and 27 patients (22.9%), respectively. Of imetelstat-treated patients, 6 (5.1%) discontinued treatment due to neutropenia (1 case, grade 4; all others, grade 3), and 4 (3.4%) discontinued due to thrombocytopenia (1 case, grade 2; 3 cases, grade 3). In addition to dose reductions and discontinuation of imetelstat, thrombocytopenia and neutropenia were managed by cycle delays in 46.6% and 50.8% of patients, by platelet transfusions in 17.8% of patients, and by concomitant therapy with growth factor support (mostly during cycles 2-4) in 34.7% of patients. Similar patterns of imetelstat dose modifications were seen in a pooled phase 2 and phase 3 safety analysis of IMerge. In the IMerge phase 3 trial, thrombocytopenia and neutropenia were the most common and most frequently reported grade 3-4 AEs during treatment cycles 1-3. However, these AEs were generally transient, reversible, and manageable through treatment delays and dose adjustments, allowing for patients to remain on treatment and continue to experience clinical benefit. Moreover, occurrence of grade 3-4 cytopenias in responders suggests that these TEAEs do not affect the efficacy of imetelstat.

Real-World Patient Characteristics, Treatment Patterns, and Outcomes in Patients with Lower-Risk Myelodysplastic Syndromes Who Have Been Treated with Luspatercept

Background: Myelodysplastic syndromes (MDS) are a group of rare, clonal bone marrow malignancies characterized by ineffective erythropoiesis. Erythropoiesis-stimulating agents (ESAs) are a treatment option for anemia in patients with lower-risk MDS (LR-MDS); however as only one in three patients respond to ESAs, there is a need for additional treatment options. In April 2020, luspatercept was approved for the treatment of anemia in adult patients with LR-MDS who failed to respond to ESAs. The aim of this study was to investigate real-world treatment patterns and early clinical outcomes in adult patients in the United States with LR-MDS receiving luspatercept. Methods: This was a retrospective observational cohort study of adult patients (aged ≥ 18 years at initial MDS diagnosis) with an International Prognostic Scoring System/Revised IPSS (IPSS-R/IPSS) classification of Very Low-, Low-, or Intermediate-risk MDS on or before the initial MDS diagnosis date +30 days, who were actively treated with a therapy of interest (including ESAs, hypomethylating agents [HMAs], erythroid maturation agents [EMAs], iron chelation therapy [ICT], white blood cells [WBCs], growth factors, chemotherapy, immunomodulating drugs [IMiDs], and platelet growth factors), and who received at least one dose of luspatercept between initial MDS diagnosis and November 1, 2022 in the COTA Vantage database which contains longitudinal, HIPAA-compliant data pertaining to the diagnosis, clinical management, and outcomes of patients with cancer from a mix of academic and community settings. The index date was the date of luspatercept initiation. Patients were required to have at least 2 months of medical data post-index unless they died during this period. All analyses were descriptive. Results: A total of 86 patients who were treated with luspatercept (median age 78.0 years, 79.1% White, 52.3% male, 80.2% ECOG 0-1) were included. Median baseline hemoglobin level was 7.8 g/dL (range: 5.3-11.4 g/dL). Median time from MDS diagnosis to luspatercept initiation was 35.4 months and the median follow-up time was 13.4 months. The majority of patients (89.5%) were previously treated with ESAs for a median duration of 9.0 months. The two most used ESAs were darbepoetin alfa (54.5%) and epoetin alfa (44.2%). In addition, 40.7% of patients had previously received a non-ESA treatment, most commonly azacitidine (62.9%) or lenalidomide (31.4%). The median duration of treatment (DoT) with luspatercept was 9.9 months. Around a quarter of patients who received luspatercept (25.6%, n = 22) received a further treatment, such as an ESA or an HMA for a median of 2.8 months. Overall, 51/76 (67.1%) patients with a baseline hemoglobin test who received luspatercept had an increase in hemoglobin of ≥1 g/dL compared with baseline (i.e. the closest hemoglobin test within 6 months prior to index date). Of these, 56.9% maintained the ≥1 g/dL hemoglobin level for ≥8 weeks and 45.1% maintained it for ≥16 weeks. Further, 44/76 (57.9%) patients with a baseline hemoglobin test who received luspatercept had an increase in hemoglobin ≥1.5 g/dL compared with baseline. Of these, 50.0% maintained the ≥1.5 g/dL hemoglobin level for ≥8 weeks and 25.0% maintained it for ≥16 weeks. Conclusion: This real-world study described treatment patterns and outcomes in patients with LR-MDS receiving luspatercept. An improvement in hemoglobin levels was observed in more than half of patients. In a quarter of patients who had a ≥1.5 g/dL increase compared to baseline, these improvements were maintained for ≥16 weeks. As this was a relatively small and descriptive study, future analyses are required to further elucidate these findings.

Treatment of Elderly Patients with Higher Risk Myelodysplastic Syndromes with Oral Azacitidine

Background Oral formulations ofhypomethylating agents decitabine (ASTX727) and azacitidine (cc-486, AZA) were approved respectively for treatment of higher risk myelodysplastic syndromes (HR-MDS) and for maintenance of acute myeloid leukemia after remission. Management of MDS patients with oral agents is relevant to improve quality of life. Oral-AZA has shown activity in lower risk MDS and its use is under evaluation in that setting. There are no data regarding maintenance of response achieved by subcutaneous (sc) AZA in HR-MDS cases by switching to the oral formulation. Aim The primary objective of the study was to explore the feasibility of replacing sc-AZA by its oral formulation in patients with HR-MDS in response. Maintenance or improvement of response and, as secondary objectives, patient reported outcome (PRO) and DNA methylation pattern were evaluated. Methods A monocentric, pilot phase 2 study was planned to enroll 11 subjects with confirmed diagnosis of MDS, IPSS-R higher risks, aged ≥ 65 years, in CR/CRi, PR or SD with HI after > 6 cycles of sc-AZA therapy (ClinicalTrial.gov NCT04806906). Patients were to receive 300 mg oral-AZA for the first 14-days of each 28-day treatment cycle until absence of benefit or disease progression. Dose of oral-AZA could be de-escalated based on toxicity. At screening and every 4 cycles, IWG response was evaluated. NGS evaluation of somatic mutations and DNA methylation analysis were performed at the same time points. DNA methylation pattern of separated BM CD34 positive cells was determined by Oxford Nanopore. At day1 of every cycle the EQ-5D questionnaire for QoL was administered. Feasibility, safety, tolerability as well as efficacy of oral-AZA were evaluated by monitoring AEs and response/loss of response, time to treatment discontinuation, and PRO. Results. As per July 31 st 2023, 11 HR-MDS patients with a median follow up of 167 days (range 47-805) were enrolled in this study. Male/female ratio was 4.5/1 with a median age of 81 yrs (67-88). At diagnosis patients belonged to IPSS-R risk categories intermediate 1/11, high 8/11, very high 2/11; IPSS-M risk categories at start of oral AZA: 3/11 very high, 6/11 high and 2/11 very low. Median number of sc-AZA cycles was 9 (range 7-52), while for oral-AZA median number of cycles was 4 (range 1-10). Oral AZA dose of 300 mg/day was maintained for all patients. DNA methylation was determined with success at baseline and every 4 cycles for all treated patients, and methylation status analyzed. None of the patients had serious adverse events related to study drug. Myelosuppressive effects were transient and Grade1/2. Patients maintained CR (4/11), PR (6/11) and SD with HI (1/11) achieved with sc-AZA, until progression. Therapy was interrupted for progression in 4 patients who evolved to AML after a median of 9 cycles of treatment with oral-AZA. Early discontinuation was experienced in 2/11 patients: in one case following a GI event grade 3 and patient decision to avoid de-escalation of the dose for subsequent cycles, in the second case because of patient reduced compliance. Both patients re-switched from oral to sc-AZA treatment and are still in response (PR). PRO analyses indicated that oral-AZA therapy improved most quality-of-life domains compared to sc-AZA. Treatment is ongoing for 4/11 patients in CR (3/4) and PR (1/4). Responses were observed across all IPSS-M risk categories. Conclusions Treatment of HR-MDS elderly patients with oral-AZAis feasible and effective. We observed duration of hematological response with a length consistent with what shown in this patient subgroup, and even after a very prolonged treatment with sc-AZA. Oral AZA was generally well tolerated and AEs did not differ from those observed for sc-AZA.

Reduced Subclone Diversity in Clonal Cytopenia of Undetermined Significance Compared to Myelodysplastic Syndrome

Introduction: Clonal cytopenias of undetermined significance (CCUS) and myelodysplastic syndromes (MDS) represent a disease continuum that are distinguished by the presence of dysplasia in >10% of blood cells. However, morphologic dysplasia is subject to high inter-observer variability, suggesting that dysplasia may not be ideal to differentiate CCUS from MDS. Defining the clonal architecture of samples from cytopenic patients may provide a more accurate objective measure of disease status than dysplasia. We hypothesize that the number and size of subclones is reduced in patients with CCUS compared to MDS, suggesting that increased subclonal diversity is a hallmark of higher-risk disease. Methods: We performed whole genome sequencing with higher exome coverage (eWGS) on bone marrow (n=58) or peripheral blood (n=4) and paired normal DNA from baseline banked samples from patients with CCUS (n=13), MDS (n=29; IPSS-R very low/low [3], intermediate [5], high/very high [19], no score [2]), and secondary AML (sAML) (n=20), including 32 previously reported patients, to define clonal architecture. Putative somatic variants, including 76 genes that are recurrently mutated in myeloid neoplasms, were validated in hematopoietic and paired normal samples, and available serial samples (n=23), using orthogonal target enrichment sequencing platforms achieving higher coverage (~600-1000x). Clonality of validated somatic mutations was defined using SciClone. Results: The absolute neutrophil count, hemoglobin, and platelet counts trended lower in MDS vs CCUS patients (median, 1.3 vs 2 K/ul [ns]; 9.3 vs 11.35 g/dL [p<0.01]; 63 vs 109.5 K/uL [ns], respectively). The ages and median number of total validated somatic mutations identified by eWGS at baseline was similar for CCUS (n=428), MDS (n=300), and sAML patients (n=420.5). We first defined the founding clone (i.e., the dominant clone with the highest median variant allele frequency [VAF]) and subclones. While the number of total clones per sample was not different between CCUS, MDS, and sAML (median, n=3 for each), the median VAF of all the mutations present in the founding clone (i.e., measure of the maximal molecular disease burden) was significantly lower in CCUS (21.3%) compared to MDS (39.2%, p<0.05) and sAML samples (45.2%, p<0.001), but MDS and sAML were not different (p=0.2) (Figure 1A). In contrast, there was no significant difference in the median VAF of subclones in CCUS and MDS samples (13.4% vs 16.8%), which were both lower than sAML (25.3%, p<= 0.01). However, the proportion of patients with no subclones (i.e., only the founding clone detected) was higher for CCUS (5/13 [38.5%]) compared to MDS and sAML (4/29 [13.8%] and 0/20 [0%], respectively, p 0.0006), suggesting that CCUS samples have reduced subclonal diversity compared to MDS. Consistent with this, genes commonly mutated in subclones occurred less frequently in CCUS vs MDS samples, including activated signaling (0/13 vs 6/29) and transcription factor genes (3/13 vs 9/29, respectively). Nine CCUS patients had serial samples sequenced (median 2 serial samples, range 1-5) at a median follow-up of 539 days (range, 84-4066 days). In CCUS patients with serial samples, there was minimal change in the founding clone (0.16%, range -3.7-23.9%) or the subclone median VAFs (0.2%, range -22.4-22.2%), with only 2 patients having a founding clone or subclone VAF increase of >5%. UPN 529198 had the acquisition of a new SRSF2(P95H)-mutant subclone 4066 days after initial banking but remained with stable cytopenias and no MDS (Figure 1B). One CCUS patient developed MDS 70 days after banking with a blast count that increased from 2% to 15% but had a negligible change in the founding clone VAF (2.8% increase). However, 3 subclones did increase in size (max VAF increase of 6.1%). In summary, while the total number of mutations is similar between CCUS, MDS and sAML samples, the clonal architecture varies across diseases. CCUS has a lower total molecular disease burden and a lower proportion of patients with a subclone compared to MDS patients in our cohort. The data suggest that defining clonal architecture and incorporating subclonal complexity in the evaluation of cytopenic patients could provide an objective measure to characterize and monitor disease burden rather than relying on the presence or absence of dysplasia, especially when considering the diagnosis of CCUS and lower-risk MDS.

Somatic Mutations and DNA Hypermethylation at Enhancers and Promoters Identify Distinct Subtypes within Lower-Risk Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a group of heterogeneous disorders caused by the accumulation of somatic mutations in the hematopoietic stem and progenitor compartment. Besides del(5q), SF3B1 or TP53 mutations, referred to as defining genetic abnormalities, mutation patterning hardly structured the classification of MDS. Mutations in epigenetic factors occur early in the development of clonal hematopoiesis leading to precocious alterations of DNA methylation implicated in oncogenesis. Convergent DNA methylation patterns related to both mutations and microenvironment imprinting may induce specific gene expression profiles and contribute to phenotypic variations. To refine a pathophysiological classification of lower-risk MDS, we combined genetic profiling to DNA methylation and transcriptome data. Methods: We enrolled 543 lower-risk treatment-naïve MDS patients at diagnosis and performed DNA-sequencing of 24 genes. DNA methylation and RNA-sequencing data were generated in a representative subset of 175 cases with available material (75 MDS-SLD/MLD, 40 MDS-EB1, 53 MDS-RS-SLD/MLD, 5 MDS del(5q), 2 MDS-U) and 7 age-matched healthy controls. IPSS-R was very low, low or intermediate in 87.4%. During a median follow-up of 2 years, 16% of MDS cases progressed to AML (MDSp). Infinium EPIC 850K array allowed after filtering the examination of methylation of 723,612 CpG sites with enrichment at enhancers and promoters. Differentially methylated regions with differentially methylated CpG sites (DMR-CpG) between cases and controls were defined with a minimum of 2 probes, a Benjamini-Hochberg-adjusted P-value cut-off of 0.05, a false discovery rate of 0.001 and a mean Δβ-value >20% at CpG sites. Consensus motifs for transcription factors were identified using Homer. Results: Unsupervised clustering on genetic profiling of 543 patients identified distinct subsets of lower-risk MDS with different clinical features: one cluster (group A) was enriched in del(5q), three clusters were characterized by SF3B1 mutations, either isolated (group B) or associated with DNMT3A (group E) or TET2 (group F), while the two remaining clusters were enriched in either complex pattern of mutations (group C) or SRSF2 mutations (group D). Genetic clusters showed significantly different clinical outcomes, clusters C, D and E having lower overall survival and higher risk of progression to high risk MDS or AML compared to other clusters. In the subset of 175 cases, a total of 2,953 unique DMR-CpGs allowed a robust repartition of patient samples in 4 groups using the k-means method. The 4 methylation groups were clinically distinct in terms of age, hemoglobin, neutrophils, monocytes, platelets, BM blasts, WHO classification, IPSS-R, and mutation pattern. A significant correlation was found between genetic and methylation groups ( P<0.001). Hypomethylated CpGs defined group 4 which was enriched in MDS-RSwith low blast count and few co-mutations, while groups 1 and 3 demonstrated hypermethylated profiles driven by TET2/ IDH1-2 mutations and TET2/ SRSF2 mutations, respectively. TET2-mutated cases exhibited an increased proportion of hypermethylated DMR-CpGs at enhancers (DME) significantly enriched in C/EBP and ETS family transcription factor motifs. In MDS without evidence of progression, we identified 1,418 DME and their gene targets of which those significantly deregulated in RNA-seq were involved in the control of translation and response to TGF-β. By contrast, in MDS with rapid progression to AML, DMR-CpGs were significantly enriched at CpG islands and promoters ( P<0.0001) and a set of 10-20 genes downstream of these promoters were specifically deregulated. Conclusion: Somatic mutations and DNA methylation at enhancers and promoters identify distinct subsets of lower-risk MDS with different clinical behavior. Hypermethylation at enhancers with C/EBP or ETS family motifs is a hallmark of MDS and may account for changes in transcription factor recruitment and cell fate. Hypermethylation of promoters with downstream effects on gene expression may indicate a propensity to rapid evolution to AML.

A Phase 1 Study of Avapritinib in Combination with Decitabine in Patients with Systemic Mastocytosis with an Associated Hematologic Neoplasm

Background and Rationale: Systemic mastocytosis (SM) is a clonal hematologic neoplasm characterized by abnormal accumulation of mast cells which can lead to symptoms related to mast cell degranulation and/or, in the case of advanced systemic mastocytosis (AdvSM), organ dysfunction due to mast cell infiltration. AdvSM is a category of SM comprised of aggressive systemic mastocytosis (ASM), mast cell leukemia (MCL), and SM with an associated hematologic neoplasm (SM-AHN). Among these, SM-AHN is the most common subtype, accounting for approximately 70% of AdvSM. A KIT D816V mutation found in up to 95% of SM cases is the primary oncogenic driver, making it a key therapeutic target. Avapritinib, a highly potent and selective inhibitor of D816V mutant KIT, has demonstrated high rates of rapid, deep, and durable responses in all AdvSM subtypes, including SM-AHN. However, a recent analysis of the EXPLORER study showed that avapritinib-treated patients were still at risk for progression of the AHN component, despite continued control of mast cell disease burden, indicating that combination therapy is likely to be required for optimal control of SM-AHN due to its inherent molecular complexity. Hypomethylating agents (HMA) form the backbone of therapy for advanced myelodysplastic syndrome (MDS) and myelodysplastic/myeloproliferative neoplasm (MDS/MPN), hematologic neoplasms most likely to co-occur with SM in patients (pts) with SM-AHN. To date, the combination of HMA and KIT inhibitors has not been clinically evaluated. In this study, we aim to assess the safety and tolerability of the combination of avapritinib and decitabine in patients with SM-AHN. Study design: The primary objective of the study is to establish the recommended dose (RP2D) of avapritinib in combination with decitabine based on dose-limiting toxicity, overall safety, and clinical activity data. A dose evaluation steering committee (DESC) comprised of participating investigators will review the totality of safety and efficacy data to determine RP2D. Secondary endpoints include SM overall response rate by the end of 6 cycles by the m-IWG consensus criteria and proposed ECNM-AIM criteria ( Gotlib et al., J Allergy Clin Immunol Pract, 2022), as well as incidence and frequency of adverse events. Exploratory endpoints will consist of patient reported outcomes, progression free survival, overall survival, and correlative biomarkers linked to mast cell disease or AHN. Adult pts with a diagnosis of SM-AHN by the WHO 2022 classification criteria will be eligible for inclusion. Eligible pts must have any of the following myeloid AHN per WHO 2022 criteria: MDS, chronic myelomonocytic leukemia, MDS/MPN with neutrophilia, MDS/MPN with SF3B1 mutation and thrombocytosis, or MDS/MPN- not otherwise specified. Patients with MDS must have intermediate, high- or very-high risk by IPSS-R. Patients with very-low or low-risk MDS by IPSS-R must be intolerant/refractory to ESA or have serum EPO > 200 U/L. A baseline platelet count of ≥ 75 x 10 9/L and ≥ 25 x 10 9/L will be required for inclusion in the dose-finding and the dose-expansion phases, respectively (Figure). Key exclusion criteria include a diagnosis of acute myeloid leukemia, history of intracranial hemorrhage or risk of major hemorrhage, prior treatment with avapritinib or decitabine with documented progression in SM or AHN component, respectively, or history of treatment with alternative KIT inhibitor or azacitidine within 4 weeks of study treatment initiation. In the dose finding part of the study, a Bayesian adaptive design will be employed to assess different doses of avapritinib (50 to 200 mg PO daily) in combination with fixed doses of decitabine (oral decitabine/cedazuridine: 35/100 mg/day or intravenous decitabine: 20 mg/m 2/day on days 1-5) in a 28-day treatment cycle. Close attention will be paid to treatment-emergent thrombocytopenia with protocol-driven treatment holds and dose modification strategies employed when platelet count drops below 50 x 10 9/L. After RP2D is determined, an additional 10 patients will be enrolled in the dose expansion phase. Patients with platelet count ≥ 25 x 10 9/L and < 75 x 10 9/L, will receive lead-in dosing with decitabine or decitabine/cedazuridine with the ability to add avapritinib if sufficient platelet thresholds are achieved. This study will open at 7 sites in the United States and is anticipated to open in January 2024.

Predictive Biomarkers of Response to Luspatercept in Patients with Myelofibrosis- (MF) Associated Anemia: Biomarker Analysis from the ACE-536-MF-001 Study

Introduction: MF is a clonal myeloproliferative neoplasm that results in fibrosis of the bone marrow and impaired hematopoiesis. Among other clinical manifestations, ineffective erythropoiesis leads to anemia resulting in poor quality of life and reduced overall survival (Passamonti et al., Blood 2010). Current treatment options for MF-associated anemia with most agents lack optimal efficacy and durability of response (Cervantes et al., Expert Rev Hematol., 2016). Luspatercept is a transforming growth factor-β (TBF-β) family ligand trap that inhibits the TGF-β-Smad signaling axis and promotes late-stage erythropoiesis. Luspatercept is approved in low-risk MDS with ring sideroblasts and β-thalassemia requiring red blood cell (RBC) transfusion. The ACE-536-MF-001 study investigates the safety and efficacy of luspatercept in the treatment of MF-related anemia. Here, through mutational and cytokine analysis of ACE-536-MF-001 biomarker samples, we sought to identify mutational and cytokine profiles associated with response. Methods: Eligible patients were divided into 4 cohorts based on transfusion dependence (TD) and treatment with ruxolitinib (RUX). Cohorts 1 and 3A were non transfusion dependent (NTD) while cohorts 2 and 3B were TD patients receiving 4-12 RBC units/84 days up to C1D1. Cohorts 3A and 3B received a stable dose of RUX. All patients received 1.0 mg/kg of luspatercept (1.33 mg/kg for cohort 3B) with titration up to 1.75 mg/kg once every 21 days. Primary endpoint was anemia response (defined as an increase of ≥ 1.5 g/dL hemoglobin (Hgb) from baseline for cohorts 1/3A or RBC transfusion free for ≥ 12 consecutive weeks for cohorts 2/3B). Secondary endpoint was mean Hgb increase ≥ 1.5 g/dL from baseline for ≥ 12 consecutive weeks for cohorts 1/3A, or ≥ 50% decrease in RBC transfusions from baseline for ≥ 12 consecutive weeks and duration of RBC transfusion-free period for cohorts 2 and 3B. Mutational analysis was performed in DNA from peripheral blood mononuclear cells using a panel targeting 74 genes. Rules-Based Medicine's Human Inflammation panel was used to measure changes in 54 serum cytokines. Nexelis custom panel was used for detection of GDF8, GDF15, erythroferrone, soluble transferrin receptor 1 (sTfR1) and hepcidin. Changes in soluble factors from cycle 1 to end of week 24 (day 169) were examined for correlation with clinical response. Results: All 4 cohorts (N = 95) displayed improvement in anemia and TD patients receiving RUX had the greatest benefit (Gerds et al. EHA 2023 S167). In the biomarker cohort (n = 63 across all 4 cohorts), mutational analysis revealed that most patients carried the JAK2 V617F mutation, and patients with SF3B1 or SF3B1 with co-occurring DTA mutations ( DNMT3A, TET2 or ASXL1) had a favorable prognosis related to anemia response (p= 0.0260, 0.0495; OR= 3.54, 3.86). In addition, JAK2 V617F patients in cohort 3B showed clinical benefit with luspatercept (OR= 6.75, p= 0.0445). Across cohorts and endpoints, the general trend of responders was low baseline (2-3-fold lower relative to nonresponders) levels of key inflammatory cytokines. Low levels of IL-10 (TD patients) and VCAM-1, TNFR2, CRP and IL-18 (NTD patients) were significant ( P < 0.01) predictors of response. Paired analysis between cycle 1 and week 24 revealed increases in alpha-2-macroglobulin, haptoglobin, TIMP1, and decrease in C3, vitamin D-binding protein, hepcidin and sTfR1 associated with anemia response. When transfusion burden reduction was used as a response criterion, ferritin, hepcidin, thrombopoietin, von Willebrand Factor, sTfR1, and beta-2-microglobulin were significantly ( P < 0.05) associated with response (Figure). In addition, Hgb increase was associated with increased TGF-β1 and VEGF levels and decreased GDF-15 and ERFE. These cytokines are implicated in iron metabolism (ferritin, hepcidin, alpha-2-macroglobulin), Hgb catabolism (haptoglobin), anemia (vitamin D-binding protein, C3), and luspatercept-target engagement (hepcidin, sTfR1). Conclusions: Our analysis identifies unique predictors of response to luspatercept treatment in patients with MF. While the data describe our findings across cohorts, cohort 3B (TD, receiving RUX), which had the highest response rate, also had higher levels of RANTES and TPO at baseline in responders. The ongoing phase 3 study, INDEPENDENCE (NCT04717414), would validate these observations in a larger cohort of patients

Do We Still Need to Perform Bone Marrow Examination in All Subjects Suspected of MDS? Evaluation and Validation of Non-Invasive (Web-Based) Algorithm

Background : The gold standard of diagnosing myelodysplastic syndromes (MDS) still requires a bone marrow examination (BME), an old invasive procedure, with possible associated pain and bleeding, and subjective interpretation with 20-25% inter-observer variability. We first developed a logistic regression formula [Oster HS et al., Leuk Res 2018], and then a non-invasive web-based diagnostic algorithm [Oster HS et al., Bld Adv 2021]. The app requires input of 10 readily available clinical and laboratory parameters (age, gender, Hb, MCV, WBC, ANC, monocytes, PLT, glucose, creatinine), resulting in diagnosing or excluding MDS, perhaps obviating the BME (Figure). Here, we performed external validation of the model, using data of MDS patients and non-MDS controls, who had not been included in the development of the model. Methods: The BM registry of Tel Aviv Sourasky Medical Center (1/2017-12/2021) was reviewed. Inclusion criteria for the MDS group were BME diagnosis, and for the controls, age >50yr, and unexplained anemia requiring BME. We excluded patients with other causes of anemia (renal failure; B12/folic acid or iron deficiency), active malignancy and other hematologic diseases. The relevant parameters were entered into the online model (at https://shiny.york.ac.uk/mds/) and the results of both groups were compared. In a sub-analysis, the model performance was tested in patients with lower risk (LR, IPSS-R<3.5) and higher risk (HR, IPSS-R≥3.5) MDS. Results: In total, 204 patients were included and compared, 103 with MDS, and 101 anemic non-MDS control patients, all with BME. The analysis of model performance (Table, upper portion) showed a sensitivity of 85.6%, specificity of 92.3%, positive predictive value (PPV) of 90.3% and a negative predictive value (NPV) of 88.4%. The algorithm was indeterminate in 26.2% of patients with MDS (BME proven), compared with 9.9% in the control group. In the sub-analysis (Table, lower portion), the model performance in the patients with LR-MDS (n=61) demonstrated sensitivity 85.1%, specificity 92.3%, PPV 90.3% and NPV 88.1%. The performance in HR-MDS (n=32), was 89.3%, 92.3%, 90.6% and 91.1%, respectively. Conclusions : This study validates the potential role of this non-invasive, easy-to-use model to assist in diagnosis, and mainly exclusion of MDS, perhaps allowing to avoid bone marrow examination in some patients. This might be especially relevant for patients suspected to have LR-MDS. Emerging technologies with data generated from peripheral blood (genetics, morphometrics) may be incorporated in the model in the future.

Safety and Preliminary Efficacy of DFV890 in Adult Patients with Myeloid Diseases: A Phase 1b Study

Background and Significance: Patients (pts) with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) have a high unmet medical need, with limited standard-of-care therapeutic approaches, particularly after failure of response to first-line agents, and with allogeneic hematopoietic transplant as the only potential curative option. Through the production of interleukin (IL)-1β and IL-18, the NLRP3 inflammasome has been implicated as a major driver of inflammation associated with acute and chronic inflammatory diseases. The NLRP3 pathway is activated in hematopoietic stem and progenitor cells and in the marrow microenvironment in myeloid neoplasms such as MDS and CMML contributing to ineffective hematopoiesis and clonal progression (Hamarsheh 2020; Basiorka 2016). DFV890, a small molecule NLRP3 inhibitor, blocks IL-1β and IL-18 secretion and pyroptotic cell death in response to a wide variety of NLRP3-dependent danger signals, both in vitro and in vivo. Therefore, DFV890 may disrupt the smoldering inflammation and provide disease-modifying benefits to pts by improving hematopoiesis. Study Design and Methods: This is an open-label, phase 1b, multicenter study with a randomized dose-optimization part and a dose-expansion part consisting of two groups evaluating DFV890 in pts with very low, low, or intermediate risk MDS (LR-MDS) per revised International Prognostic Scoring System (IPSS-R) criteria and low or intermediate-1 risk CMML (LR-CMML) per CMML-specific Prognostic Scoring System (CPSS) criteria (NCT05552469). Eligible pts must be 18 years of age, with an Eastern Cooperative Oncology Group performance status ≤2, candidates for serial bone marrow assessments who are willing to undergo a bone marrow aspirate/biopsy during the trial, and meet one of the following: (a) IPSS-R-defined LR-MDS who failed to respond to or did not tolerate erythropoiesis-stimulating agents (ESAs) or luspatercept or hypomethylating agents (HMAs) and pts with del 5q who failed to respond to or did not tolerate lenalidomide; (b) CPSS-defined LR-CMML who failed to respond to or did not tolerate hydroxyurea or HMAs. Key exclusion criteria include treatment with systemic antineoplastic or any experimental therapies within 28 days (or 5 half-lives, whichever longer); unresolved treatment-related toxicities prior to the first dose of study treatment; previous treatment with agents targeting the NLRP3 inflammasome and the IL-1 pathways; prior use (≤1 week or 5 half-lives, whichever is longer) of hematopoietic colony-stimulating growth factors, thrombopoietin mimetics or ESAs; and concomitant medications, known to modulate cytochrome P450 enzymes. DFV890 is administered orally twice daily (bid) for a minimum of 24 weeks (6 cycles of treatment [1 cycle=28 days]) until treatment discontinuation. In the dose-optimization part, pts are randomized to receive either low dose or high dose bid and stratified by indications. The recommended dose (RD) determined from this part is further explored in the dose-expansion part to confirm safety and tolerability of DFV890 and explore preliminary efficacy. The primary objective is to assess safety (incidence and severity of adverse events, and dose-limiting toxicities) and tolerability to then determine the optimal RD for DFV980. Secondary objectives include assessment of DFV890 pharmacokinetics, evaluation of the preliminary efficacy of DFV890 on transfusion burden, and hematologic improvement: time to onset of transfusion independence; duration of response, best overall response, overall response rate, progression-free survival, and time to progression; and reduction in spleen volume (for CMML). Key exploratory objectives include patient perceptions of tolerability as measured by patient-reported outcomes; and determination of genetic characteristics and potential predictive markers of efficacy and/or resistance. The study is currently enrolling in Singapore, Hong Kong, and the USA with plans to treat approximately 80 pts. The first patient first visit was achieved on May 8, 2023.

Efficacy and Safety of Luspatercept +/- Erythropoiesis-Stimulating Agent (ESA) in Patients with Myelodysplastic Syndromes with Ring Sideroblasts (MDS-RS): A French Multicenter Prospective Real-Life Registry

Background EMA has recently approved Luspatercept (LUSPA) for the treatment of anemia in adult patients with RBC transfusion-dependent (TD) very low- to intermediate- risk MDS-RS or MDS/MPN with ringed sideroblasts and thrombocytosis (MDS/MPN-RS-T) having failed an ESA. We designed a French observational registry of patients treated with LUSPA according to this label. In case of primary/secondary failure to LUSPA, we also investigated the effect of adding an ESA to LUSPA. The basis of this combination followed a GFM trial showing that, in non-del 5q lower risk MDS failing an ESA, Lenalidomide + ESA gave better results than Lenalidomide alone (Toma A et al. Leukemia. 2016 Apr;30(4):897-905). In a phase I study (GFM Combola trial), we found no unexpected side effects in the LUSPA -ESA combination (unpublished). Patients and treatment This French multicenter prospective observational registry started when the drug became available (July 2022), with a starting dose of 1 mg/kg SC every 3 weeks (2 infusions) and, in the absence of erythroid response increase to 1.33mg/kg (2 injections) and to 1.75 mg/kg (3 injections). In the absence of response after those 7 infusions, the addition of ESA (30 KU /week during 1 month and, if no response, 60 KU/week during 3 months) was recommended. Results Between July 2022 and January 2023, 108 patients (median age 70 years, 47% males) were included. Median time from diagnosis to LUSPA treatment was 64 months (IQR 40-99). According to WHO 2016, 86% of the patients had MDS-RS, 9% MDS-RS-T, and 5% MDS-EB1 or MDS-MLD (but with > 15% ringed cells and/or SF3B1 mutation). IPSS-R was very low, low, int in 96%, and high in 4%, IPSS-M very low/low/moderate low in 82%. Sixty-six of the 73 (90%) patients tested molecularly had SF3B1 mutation. All patients had received an ESA and 44 (41%) other treatments (1 to 6, median 1). The median duration of LUSPA exposure was 6.5 months (range 0.5-11), and 94% of patients had received at least 2 months of treatment. Erythroid response (HI-E, according to IWG 2018 criteria) to LUSPA alone was currently evaluable in 83 patients; 76 of them were RBC-TD before LUSPA (23 low TB (LTB) (1-5 units /8 weeks) and 53 high TB (HTB) (≥ 6 units /8 weeks)), and 30 (39%) of these achieved RBC-TI with no relapse after a median of 6.5 months (range 4.4-11). All 9 non-TD patients obtained HI-E and were still responders after a median of 8 (range 6.5-9) months. Of the 85 patients evaluable for response to LUSPA alone, 34% and 48% required a dose increase once or twice, respectively. The prognostic value of IPSS-R karyotype, IPSS-R, number of somatic mutations, LTB, HTB, number of treatments before LUSPA, previous lenalidomide exposure, and iron chelation was analyzed for their prognostic value on HI-E. In multivariate analysis, HTB was the only variable statistically associated with lower HI-E (OR 0.19 [95%CI: 0.03-0.91, p=0.047] independently of IPSS-R and number of somatic mutations. At least 1 adverse event (AE) was seen in 38/103(37%) of the patients who received at least 2 doses of LUSPA, and 12 patients presented at least one severe AE (grade 3-4 according to CTCAE 5.0): including dizziness (in 5 patients), asthenia (n=4), peripheral and axial arthralgia (n= 4), headache (n=2), described by the patients as different from those they experienced with anemia. With a median follow-up of 6 months (IQR 5-8), 20 patients (18.5%) had discontinued LUSPA before 6 months of exposure due to severe AE (n=8, 7.4%, asthenia, arthralgia, dizziness, headache), lack of HI-E (n=3), disease progression (n=3), infection (n=3), death from intercurrent disease (n=2), acute coronary syndrome (n=1). After LUSPA failure, 26 patients (24.1%) received a combination of LUSPA and ESA and are currently followed. Efficacy and safety will be presented at the meeting. We also tried to correlate gene expression and GDF-11 levels with response. Results will be available at the meeting. Conclusions In this real-life study, we confirmed the results of LUSPA in MDS-RS reported in the MEDALIST study. We observed a significant number of adverse events attributed to LUSPA, some of which led to treatment discontinuation. The importance of RBC transfusion burden was the only prognostic factor of erythroid response.