International Working Group Research Articles

Platelet Response in Pacritinib-Treated Patients with Cytopenic Myelofibrosis: A Retrospective Analysis of PERSIST-2 and PAC203 Studies

Background: Myelofibrosis (MF) is a myeloid malignancy characterized by clonal hematopoisis, bone marrow fibrosis (BMF) and ineffective extramedullary hematopoiesis, resulting in progressive cytopenias. Thrombocytopenia is both prognostic of poor outcomes and predictive of treatment intolerance with the JAK1/2 inhibitor ruxolitinib, which exacerbates cytopenias. Pacritinib is a JAK1-sparing inhibitor of JAK2/IRAK1/ACVR1 that can be administered at full dose to patients regardless of baseline platelet count (PLT). While prior studies have shown that pacritinib is associated with PLT stability in most patients, PLT improvement has not been described outside of a recently published case report ( Yacoub A, et al. JCO Precis Oncol. 2023;7:e2200523). Here, we report rates of hematologic improvement in PLTs (HI-P) with pacritinib across two clinical trials. Methods: Patients with baseline PLT ≤100x10 9/L on the pacritinib 200 mg BID arms of the phase 3 PERSIST-2 study (randomized ≥12 weeks prior to study termination) or the phase 2 dose-finding PAC203 study were included. HI-P was defined per International Working Group (IWG) criteria (baseline PLT <20x10 9/L: increase to >20x10 9/L and by at least 100%; baseline PLT 20-100 x 10 9/L: absolute increase of ≥30x10 9/L) in the absence of PLT transfusions, sustained over any 8 weeks while on treatment. Efficacy outcomes (reduction in spleen volume, symptom score, and BMF) were compared between HI-P responders vs non-responders (those who did not meet IWG criteria). Rates of PLT improvement were also analyzed on the best available therapy (BAT) arm of the PERSIST-2 study over the treatment period (end of study treatment). Results: Of 117 patients randomized to pacritinib (75 from PERSIST-2, 42 from PAC203), 16% (n=19) experienced HI-P on study (as defined in methods). Additionally, 14 of the 19 HI-P patients had sustained platelet improvement over ≥12 weeks). By contrast, only 5% (4/77) of patients on BAT achieved HI-P response prior to end of study treatment. HI-P responders on pacritinib compared to non-responders, had numerically higher median baseline PLT count (63 vs 45x10 9/L) and hemoglobin (Hb; 10.3 vs 8.8 g/dL). A similar percentage had prior (<30 days) JAK2 inhibitor exposure (68.4% vs 66.3%) and JAK2V617F mutation (78.9 vs 74.5%); median JAK2 allele burden was low in both responders and non-responders (26.7% vs 36.9%). Among HI-P responders with prior ruxolitinib exposure, most (85%, 11/13) had recent exposure within the prior 30 days, with median dose of 10 mg BID. PLT improvement was noted within the first 12 weeks in most HI-P responders, whereas PLT count remained stable, on average, among non-responders ( Figure 1a). To evaluate if recent ruxolitinib exposure and washout of drug was responsible for HI-P, we analyzed the subset of patients with ruxolitinib exposure in previous 30 days (11/19). The mean platelet count increased from 56 to 141x10 9/L at week 12. In the remaining 8/19 patients without recent ruxolitinib exposure (n=6 were treatment naïve), platelets increased from 59 to 102 x 10 9/L at week 12. While there was no difference in the magnitude of spleen volume or symptom score reduction in HI-P responders vs non-responders, a correlation with change in BMF was noted. Among the 36 patients with available bone marrow data from baseline and week 24, HI-P responders were numerically more likely to have BMF reduction (67%, n=4/6) compared to non-responders (23%, n=7/30, P=0.057, Figure 1b). There was no difference in the rate of hemorrhagic events (by standardized MedDRA queries) in PLT responders vs non-responders (47% vs 46%), though grade ≥3 bleeding was observed at lower frequency in responders compared to non-responders (10.5% vs 16%). Other commonly reported adverse events with pacritinib occurred at similar frequency between responders and non-responders. Discussion: PLT improvement meeting IWG criteria occurs in a subset of MF patients treated with pacritinib and does not seem to be explained by changes in spleen volume. Further studies are warranted to assess the correlation between hematologic improvement and BMF reduction with pacritinib. It is possible that pacritinib's unique mechanism of action as an IRAK1 inhibitor could result in modulation of the bone marrow microenvironment and thrombopoiesis. Study funded by CTI BioPharma Corp., a Sobi company.

Caplacizumab Treatment in Elderly Patients with iTTP: Updated Experience from the Spanish TTP Registry

Introduction Immune thrombotic thrombocytopenic purpura (iTPP) is a rare microangiopathic thrombotic disorder with severely reduced levels of ADAMTS13 due to the presence of autoantibodies. It has classically been treated with plasma exchange (PEx) therapy and steroids, with the introduction of novel therapies in recent years such as rituximab and caplacizumab. Data concerning caplacizumabs' efficacy and safety profile in elderly patients is scarce, as iTTP is rarely presented in this population. We aimed to compare response to treatment with caplacizumab as well as safety, and tolerability in patients ≥60 years compared to those aged <60. Mat&Met Data were obtained from the Spanish TTP Registry. Patients were eligible if the diagnosis of iTTP was confirmed by ADAMTS13 activity <20%, presence of anti-ADAMTS13 autoantibodies, and had received caplacizumab at any time during the acute episode. Response criteria were defined following the revised criteria published by the International Working Group (Cucker et al. 2021). Statistical analysis was performed using EzR software, based on R commander (R Commander Version 2.6-1). Results A total of 104 patients from 39 centers, diagnosed from November 2018 to April 2023 were included (93 first episodes and 11 relapses). Twenty-nine patients (28%) were ≥60 years (Group 1) and 75 were <60 years (Group 2). Main characteristics of these patients are detailed in Table 1. Front-line treatment consisted of PEx and steroids in every patient, while rituximab was administered in 84% of patients. Caplacizumab was administered at a median (range) of 3 days (0-26) after diagnosis in patients <60 years and 5 days (0-23) in patients ≥60 years ( P= n.s.). Caplacizumab was administered as front-line therapy (n=21), after an exacerbation (n=5) or due to refractoriness (n=3) in the cohort of patients ≥60 years, and this occurred in a similar proportion in patients <60 years (58, 12 and 5, respectively; P= n.s.). The duration of treatment with caplacizumab was 34 (range, 1-77) and 35 days (range, 1-188) in patients ≥60 and <60 years, respectively ( P= n.s.). Final outcomes are detailed in Table 2. One patient ≥60 years died due to refractory disease despite starting caplacizumab during the first 24h after diagnosis Three of the 21 patients receiving caplacizumab as front-line treatment in Group 2 suffered an exacerbation (two due to treatment discontinuation and one while receiving caplacizumab). In 5/29 patients in Group 2, therapy with caplacizumab was delayed due to initial hemorrhagic symptoms (n=3) or ongoing anticoagulation or antiaggregation (one each). Bleeding motivating transient caplacizumab discontinuation occurred in five patients (17%) (subarachnoideal hemorrhage [one patient], hematuria, and pericatheter hemorrhage [one patient], abdominal hematoma, gastrointestinal, and gingival hemorrhage [one each]), and this was more frequent than in younger patients (one case of rectal bleeding [1.3%], P= .006). No other side-effects were reported. Conclusion Association of caplacizumab to PEx and immunosuppressive therapy improves outcomes in elderly patients with iTTP, although relevant bleeding complications might be higher than in younger patients.

AK117 (anti-CD47 monoclonal antibody) in Combination with Azacitidine for Newly Diagnosed Higher Risk Myelodysplastic Syndrome (HR-MDS): AK117-103 Phase 1b Results

Background: CD47, an immune checkpoint overexpressed by tumor cells, plays a crucial role in evading the antitumor immune response. AK117, an IgG4 monoclonal antibody (mAb) targeting CD47, has emerged as a potential best-in-class therapy with high affinity binding to CD47 and without inducing hemagglutination effects. By blocking CD47, AK117 effectively triggers macrophage-mediated phagocytosis of hematological malignancy cells, and in combination with azacitidine (AZA), it synergistically enhances the activation of “eat me” signals. In this study, we present the Phase 1b data from the AK117-103 study conducted in patients with newly diagnosed higher risk myelodysplastic syndrome (HR-MDS). Methods: Eligible patients with newly diagnosed intermediate/high/very high-risk MDS, determined by the Revised International Prognostic Scoring System (IPSS-R) prognostic risk score >3, were enrolled to receive combination therapy with AK117 and AZA. AK117 was administered intravenously (IV) following various dosing regimens (20-30 mg/kg once weekly [QW], or 20-45 mg/kg every 2 weeks [Q2W], or 30 mg/kg every 4 weeks [Q4W]), whereas AZA was administered subcutaneously (SC) at the standard dosage (75 mg/m 2, Day 1-7, Q4W). The primary endpoints of this study were safety/tolerability and the complete remission (CR) rate based on the International Working Group (IWG) 2006 response criteria. Results: As of June 9, 2023, 72 patients were enrolled (median age: 66 years, 69.4% males). Most patients exhibited abnormal hematologic conditions at baseline, including decreased hemoglobin, neutrophil count, and platelet count. Specifically, 69.4% of patients had Grade ≥3 anemia, 61.1% had Grade ≥3 neutrophil count decrease, and 47.2% had Grade ≥3 platelet count decrease. For the recommended phase 2 dose (RP2D) group, treated with a combination of AK117 30 mg/kg Q2W and AZA, 30 patients were enrolled with a median age of 67 years, 80.0% of whom were males. According to IPSS-R risk assessment, 33.3%, 23.3%, and 43.3% of patients had intermediate, high, and very high risk, respectively. 30.0% of patients had poor-risk cytogenetics, with 23.0% of those being complex. After a median follow-up of 6.6 months (ranging from 0.4-17.2 months), anemia (a primary adverse event associated with CD47 blocking antibodies) occurred in 30.6% (22/72) of the patients, of which Grade ≥ 3 anemia accounted for 22.2% (16/72). Other commonly observed treatment-emergent adverse events (TEAEs) (≥30%) included decreased neutrophil count (77.8%), decreased white blood cell count (72.2%), decreased platelet count (69.4%), pyrexia (58.3%), decreased lymphocyte count (41.7%), constipation (41.7%), and vomiting (31.9%). Three patients (4.2%) discontinued treatment due to TEAEs. The efficacy of AK117 was compared at different dosages, and ultimately, 30mg/kg Q2W was chosen as the RP2D. As of June 21, 2023, among 27 evaluable patients, the CR rate was 48.1%. 8 patients achieved marrow CR (5 also with hematologic improvement [HI]), and 2 patients achieved HI alone. Among 24 evaluable patients with ≥ 3 months follow-up, the CR rate further escalated to 54.2%. Of 13 evaluable patients who initially required red blood cells (RBC) transfusions, 8(61.5%) became independent of RBC transfusion. Conclusions: AK117 in combination with AZA was well tolerated with low incidence of anemia and demonstrated promising efficacy in patients with newly diagnosed HR-MDS.

A Phase II Study of Vibecotamab, a CD3-CD123 Bispecific T-Cell Engaging Antibody, for MDS or CMML after Hypomethylating Failure and in MRD-Positive AML

Background Leukemic stem cells have high expression of CD123 compared to normal hematopoietic stem cells and is therefore a therapeutic target in multiple leukemias including acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and chronic myelomonocytic leukemia (CMML). Vibecotamab (formally XmAb14045) is a CD3-CD123 bispecific engaging antibody that has shown clinical activity in relapsed/refractory AML, particularly in low-blast disease. We therefore sought to evaluate vibecotamab in other low-blast states, including MDS or CMML after hypomethylating agent failure and MRD-positive AML. Methods In this two-arm, open-label, phase II study, adults with either MDS (IPSS-R intermediate or higher risk) or CMML (CMML-1 or CMML-2) after failure of hypomethylating agents or AML in first or second morphologic remission with detectable MRD at a level of ≥0.1% by flow cytometry were eligible. CD123 expression ≥20% on aberrant myeloid blasts was required for enrollment. Vibecotamab was given IV in a ramp-up dose schedule on days 1 (0.43µg/kg), 3 (0.75µg/kg), 5 (1.1µg/kg), and 8 (1.7µg/kg) in cycle 1, followed by weekly doses of vibecotamab at a dose of 1.7µg/kg. Patients (pts) received up to 4 cycles of vibecotamab in 28-day cycles. The primary endpoint of the MDS/CMML cohort was response rate (CR + mCR + PR + HI + clinical benefit) within 4 cycles. The primary endpoint of the AML MRD cohort was the MRD negativity rate within 4 cycles. Results Between May 2022 and July 2023, 23 pts were treated (11 MDS/CMML, 12 AML MRD). Baseline characteristics are shown in Table 1. In the MDS/CMML cohort, 7 pts (63%) had received two or more prior lines of therapy, 8 pts (73%) had prior venetoclax exposure, and 2 pts (18%) had prior hematopoietic stem cell transplant (HSCT). Six MDS pts (66%) were IPSS-R high or very high risk. In the AML cohort, 6 pts (50%) had received two or more lines of prior therapy, 11 pts (92%) had prior venetoclax exposure, and 5 pts (42%) had prior HSCT. Ten pts (83%) were ELN 2022 adverse risk. The baseline CD123 expression was 72% (range, 43%-99%) in the MDS/CMML cohort and 89% (range, 55%-99%) in the AML MRD cohort. The baseline MRD by flow cytometry in the AML MRD cohort was 1.1% (range, 0.1%-3.9%). Responses are shown in Table 2. In the MDS/CMML cohort, 7 pts responded (64%), with 6 pts (56%) achieving marrow complete remission (mCR) and 1 pt (9%) achieving hematologic improvement (HI) per International Working Group (IWG) 2006 criteria. Among the 9 MDS pts, 4 (44%) achieved mCR + HI (2 HI-N, 1 HI-P, and 1 HI-P + HI-N), and 1 (11%) achieved HI (HI-N + HI-P). Per revised IWG 2023 MDS response criteria, 5 of the 9 MDS pts (56%) achieved complete remission with limited count recovery (CR L). Two of 4 MDS pts (50%) with TP53 mutations achieved CR L. Both CMML pts achieved mCR, with one pt also achieving HI-N. Among 9 pts with baseline bone marrow blasts =>5% at trial enrollment, 6 (67%) achieved a mCR, with or without HI. Best response occurred after the first cycle in all pts. CD123 expression was not associated with likelihood of response. Of the 7 responders, 5 are in ongoing response (range 0.3-6.9 months), one died in CR L from non-hematologic complications (heart failure), and one relapsed 5 months after achieving CR L. Of the 12 pts in the AML MRD cohort, 3 (25%) achieved MRD negativity, all of which occurred after 1 cycle of vibecotamab. Among the 3 responders, all were ELN adverse risk and had prior venetoclax exposure, 2 had prior HSCT, and 1 had inv(3). The median MRD and CD123 expression in responders was 0.2% (range 0.1%-0.2%) and 98% (range 95%-99%) vs 1.8% (range 0.5%-3.9%) and 87% (range 66%-96%) in non-responders, respectively. At last follow-up, all 3 responders are still in MRD-negative remission (range 3.2-12.8 months). Vibecotamab was well-tolerated with no pts requiring dose reductions or being taken off study due to adverse events. Ten pts (44%) experienced grade 2 infusion reactions and 1 pt (4%) experienced a grade 3 infusion reaction. Myelosuppression was minimal, consistent with previous studies of vibecotamab. Conclusion Vibecotamab was safe and active in low-blast, high-risk myeloid diseases, with a response rate of 64% in MDS/CMML after HMA failure and 25% in MRD-positive AML. The clinical activity of vibecotamab, including in pts with prior venetoclax exposure and/or HSCT, and its lack of clinically significant myelosuppression provide rationale to combine it with other agents in AML, MDS, and CMML.

Preliminary Results from a Phase 1b Dose De-Escalation Stage of Abnl-Marro 001: An International MDS/MPN Working Group Study

Background: Myelodysplastic/Myeloproliferative neoplasms (MDS/MPN) represent a group of rare hematologic malignancies, distinguished by their concurrent dysplastic and proliferative features. Patients with these neoplasms have an increased risk of acute leukemia transformation and often present with extramedullary and constitutional symptoms. The only approved therapies for MDS/MPNs are hydroxyurea, decitabine (oral decitabine/cedazuridine and parenteral decitabine) or azacitidine (parenteral) for pts with CMML. Given the rarity and the heterogeneity of MDS/MPNs, prospective studies focusing specifically on MDS/MPN have been uncommon, and refining treatment strategies has been difficult. ABNL-MARRO ( A Basket study of Nove l therapy for untreated MDS/MPN and Relapsed/ Refractory Overlap Syndromes) is an international cooperative effort that leverages the expertise of the MDS/MPN International Working Group (IWG) and provides a framework for collaborative studies around the world to advance treatment of MDS/MPN and to explore clinical and pathologic markers of disease severity, prognosis, and treatment response (Moyo TK et.al BMC Cancer. 2022). Methods: ABNL-MARRO 001 (AM-001) is an open-label, phase 1b/2 study testing the treatment combination of ASTX727 (days 1-5), a fixed dose oral combination pill containing 35 mg of the DNMTi decitabine (DEC) and 100 mg of the cytidine deaminase inhibitor cedazuridine (CED), together with a series of active agents in myeloid disease (see Figure 1a) for MDS/MPN. In arm A, ASTX727 is combined with itacitinib 300 mg (days 1-28), a selective JAK1 inhibitor in newly diagnosed and relapsed/refractory (R/R) pts. Here we report results from the 3+3 dose de-escalation phase 1b portion used to determine the recommended Phase 2 dose (RP2D) in arm A. Dose-limiting toxicities (DLTs) were assessed in cycle 1. Disease response was assessed by the MDS/MPN IWG response criteria (Savona et.al., Blood. 2015). Results: Seven patients were enrolled with a median age 75 (range 32-82) years with newly diagnosed (4 pts) or R/R (3 pts) MDS/MPN. Three patients had CMML, 2 had MDS/MPN-U, and 2 had refractory MDS/MPN RST. One patient was not DLT evaluable given severe disease-induced cytopenia, and was not included in the assessment (patient 4 in Figure 1b). The majority of pts experienced a treatment-emergent adverse event (TEAE) of any grade; the most common (≥30% of pts) were thrombocytopenia (50%), neutropenia (30%), and constipation (30%); 50% of pts experienced a Grade ≥3 TEAE; the most common was neutropenia (30%). No DLTs were reported, and these AEs were consistent with what has been reported in the use of ASTX727 (Savona et al. Blood. 2022). One patient achieved a CR, and two additional patients had the best overall response of optimal marrow response after receiving 6 cycles of treatment. All patients are alive with a median follow-up of 12 months (range 6-17 months). The clinical responses and time-on-treatment of all pts in phase 1b are summarized in Figure 1b. Summary/Conclusion: Based on the preliminary results of the phase 1b study, the dosing schedule of 35 mg DEC / 100 mg CED daily for 5 days in combination with itacitinib 300 mg daily for 28 days was selected as the RP2D as it balanced clinical efficacy with an acceptable and manageable safety profile. This regimen and dose are being utilized in a 28-day cycle in the ongoing global, multi-center phase 2 study (NCT04061421).

Overall Survival and Erythroid Response in Patients with Low-Risk Myelodysplastic Neoplasms after First-Line Treatment in a Low-Middle Income Country

Introduction Myelodysplastic neoplasms/syndromes (MDS) are a heterogeneous group of clonal disorders characterized by ineffective hematopoiesis and an increased risk of transformation to acute myeloid leukemia (AML). Current standard risk stratification model, the Revised International Prognostic Scoring System (IPSS-R), classifies patients into lower (≤3.5 points) or higher risk MDS. Lower-risk MDS (LR-MDS) treatment is based on the prevailing cytopenia and intends to improve symptomatic burden and minimize transfusion dependency. Anemia is present in 80-90% of patients with MDS. Throughout most of the course of the disease, patients with MDS have a hemoglobin < 10 g/dL, which leads to a decreased quality of life. Also, 50% of patients with MDS will eventually need red blood cell transfusions. Current options for the active treatment of anemia in LR-MDS are limited and vary among countries. Although erythropoiesis stimulating agents (ESAs) are considered standard of care in the absence of del5q, immunosuppressive therapy (IST) and androgens are still used in low income countries. The present study aims to evaluate whether erythroid responses and overall survival differ in patients with LR-MDS, based on their first-line treatment. Methods This is a retrospective study in patients with LR-MDS at Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, a tertiary care center in Mexico City. Eligible patients were diagnosed between January 2002 and December 2022 according to World Health Organization (WHO) 2016 criteria. Response was assessed according to International Working Group (IWG) 2018 criteria. We defined erythroid response (HI-E) as the sum of the responses achieved within different transfusion burden categories. First line therapy included ESAs, IST (cyclosporine ± eltrombopag), and androgens (mesterolone, danazol). These were compared through bivariate analysis, Kaplan-Meier curves and log-rank test. Results Until December 2022, 109 LR-MDS patients were considered for inclusion. Among them, 29 patients were lost to follow-up, and 25 patients were solely observed without any further therapy. Also, 7 patients who received other therapies were excluded. Ultimately, 48 patients were included in this analysis, 56.3% (n=27) were female, mean age was 62.8 (±15.9) years. Based on WHO 2016 classification, MDS with uni- and multilineage dysplasia was present in 58.3% (n=28) of the patients, while 29.2% (n=14) had hypoplastic MDS. Anemia was present in 89.6% (n=43) of the patients. When evaluating transfusion burden, 37.5% (n=18) of patients were non-transfusion dependent (NTD), 31.3% (n=15) low-transfusion burden (LTB), and another 31.3% (n=15) high-transfusion burden (HTB). ESAs and IST were the most frequently used frontline therapies, each accounting for 41.7% (n=20) of the patients; the remaining 16% (n= 8) received androgens. When comparing baseline characteristics between treatment arms, we found lower hemoglobin values and a greater proportion of severe anemia in ESA-treated patients (p= 0.039, p= 0.036), however, no differences in transfusion burden was observed (p= 0.212). Erythroid response rates were 25% (n=5), 20% (n=4) and 62.5% (n=5) among those treated with ESAs, IST and androgens, respectively (p= 0.071). When assessing HI-E by transfusion burden, no differences were observed between treatment arms except in HTB patients (p= 0.023). Neither time to response, nor duration of response were significantly different between treatment groups ( Table 1). Importantly, 3 of the 4 responders in the IST group received cyclosporine monotherapy, also 50% were hypoplastic MDS. After a median follow up of 47 months (IQR:22.5-85.5), the median overall survival(OS) for the entire cohort was not reached. The 3-year-OS rates for IST, ESA and androgens were 94%, 54% and 50%, respectively (p= 0.018) ( Figure 1). Conclusions In spite of the bias and limitations in the retrospective nature of this study, IST seems to be a valid option in frontline therapy for LR-MDS, since HI-E rates are similar to those observed with ESAs. Additionally, IST group showed a better OS. Results obtained with androgens merit further study and should be interpreted with caution because of the sample size.

Time to Achieve Platelet Count Response after Intravenous Efgartigimod in Adults with Primary Immune Thrombocytopenia: A Phase 3, Multicenter, Double-Blinded, Placebo-Controlled, Randomized Clinical Trial (ADVANCE IV)

Background In primary immune thrombocytopenia (ITP), immunoglobulin G (IgG) anti-platelet autoantibodies contribute to platelet clearance and impair platelet production. IgG homeostasis is regulated by the neonatal Fc receptor (FcRn), which binds to IgG in a pH-dependent manner and recycles bound IgG. Efgartigimod (EFG), a human IgG1 Fc fragment, is a natural ligand of FcRn engineered to bind competitively to FcRn with high affinity, preventing recycling of endogenous IgG, thereby reducing IgG levels, including pathogenic IgG autoantibody levels. Methods Intravenous (IV) EFG was evaluated in ADVANCE IV, a phase 3, multicenter, randomized, double-blinded, placebo (PBO)-controlled trial (NCT04188379) in adults with persistent or chronic ITP (Broome CM, et al. ASH 2022). Participants who received 2 prior or 1 prior and 1 concurrent ITP therapy with an average of 2 platelet (PLT) counts of <30×10 9/L during screening were randomized 2:1 to receive EFG IV 10 mg/kg or PBO IV for 24 weeks. Concurrent oral corticosteroids, immunosuppressants, dapsone, danazol, fostamatinib, and oral thrombopoietin receptor agonists were permitted but required to remain at the entry dosage and frequency. Participants received weekly dosing of either EFG or PBO (weeks 1-4) followed by response-dependent weekly or every-other-week dosing (weeks 5-16) and then maintained their dosing regimen from weeks 17-24. PLT counts were measured weekly starting at day 7 after treatment initiation. The extent of disease control, defined as cumulative weeks with PLT counts of ≥50×10 9/L in the chronic ITP population, was assessed as a key secondary endpoint. This analysis evaluates trends in time to response in ADVANCE IV. The time to achieve 2 consecutive PLT counts of ≥50×10 9/L was evaluated as a secondary endpoint. Time to 2 consecutive PLT counts of ≥100×10 9/L and time to single counts of ≥50×10 9/L and 100×10 9/L were analyzed as defined a priori. Post hoc Kaplan-Meier (KM) analyses, including time to a single PLT of ≥30×10 9/L and time to the International Working Group (IWG) response, were also performed. Change from baseline in mean PLT counts over time was evaluated based on a mixed model for repeated measurements. Results One hundred thirty-one participants (118 chronic ITP, 13 persistent ITP) were randomized (86 EFG, 45 PBO). Least-squares mean estimate changes from baseline in PLT counts were significantly different in EFG group compared with PBO group starting at day 7 (22×10 9/L vs -1×10 9/L; P=0.0293) and remained significant at most time points throughout the study. 38.4% of EFG-treated participants compared with 11.1% of PBO treated participants achieved a PLT count of ≥30×10 9/L in 7 days. The EFG group showed a higher proportion of PLT count responders ≥50×10 9/L on ≥4 occasions until week 12 compared with PBO (34.9% vs 4.4%, respectively). Based on KM analysis, 31.8% of participants receiving EFG and 2.2% of those receiving PBO achieved 2 consecutive PLT counts of ≥50×10 9/L by day 42 (Figure). 41.5% of participants receiving EFG vs 11.4% of those receiving PBO achieved the first PLT count ≥50×10 9/L by day 42. 22.5% of participants receiving EFG vs 2.2% of those receiving PBO achieved the first PLT count ≥100×10 9/L by day 42 (Table). The cumulative number of weeks in disease control was significantly higher in the EFG group compared with PBO (mean [SD]: 6.1 [7.66] vs. 1.5 [3.23]; P=0.0009) (Broome CM, et al. ASH 2022).KM estimates for IWG response by day 42 in the overall (chronic and persistent ITP) population were 29.7% in participants receiving EFG vs 4.6% in those receiving PBO. Overall, EFG was well tolerated; most adverse events were mild or moderate in severity. Conclusions In ADVANCE IV, EFG demonstrated a rapid PLT count increase, as early as the first time point measured (7 days after EFG treatment). Irrespective of the specific measure of response utilized, these data demonstrate that at all time points evaluated more participants in the EFG group achieved response compared with the PBO group. In addition to this early response, significantly more sustained responses were observed in the EFG group compared with the PBO group. The response rate, regardless of definition, in participants who received EFG continued to increase over time suggesting that some participants may have delayed responses to EFG. These data further demonstrate early and sustained responses with EFG in ITP.

Involvement of the JAK-STAT Pathway in the Molecular Landscape of Fusion-Free Myeloid Neoplasms with Eosinophilia

Introduction. Gene fusions leading to the constitutive activation of tyrosine kinases (TK) such as PDGFRA, PDGFRB or FGFR1 have been the first recurrent genetic defects involved in myeloid hypereosinophilic syndromes (HES). Although activation of the Janus kinase (JAK)/Signal Transducer and Activator of Transcription(STAT) pathway is critical for eosinophil production and survival, genes involved in the JAK/STAT pathway are not included in most next-generation sequencing (NGS) panels used for the etiological workup of hypereosinophilia (HE). Methods. A custom 149-gene NGS panel including subunits of the IL3/IL5/GM-CSF receptors, TK ( PDGFRA/B, FGFR1, ABL1, FLT3, KIT), intracellular proteins of the JAK-STAT and RAS-MAPK pathways was performed in 64 consecutive adult patients (experimental group) referred between March 2012 to June 2023 to the French Reference Center for Hypereosinophilic Syndromes (CEREO) for HE/HES displaying at least one clinic-biological feature suggestive of myeloid neoplasm ( i.e. splenomegaly, other unexplained CBC abnormality besides HE, increased serum tryptase and/or vitamin B12 levels, corticosteroid-refractory HE and/or sensitivity to either TK inhibitors or JAK inhibitors). All of them were negative by PCR and/or FISH analyses for gene rearrangements involving PDGFRA, PDGFRB or FGFR1. Patients with lymphocytic HES (n=7), idiopathic HES (n=26) and HE of undetermined significance (n=11) were used as controls (total, n=44). Results. Concordant with the latest recommendations of the international cooperative working group on eosinophil-associated disorders, at least one mutation was reported in 50/64 (78%) patients of the experimental group versus 8/44 (18%) patients in the control group (p<0.001) when applying a threshold of at least 3% of variant allele frequency (VAF). Mutations in the control group implied genes involved in age-related clonal hematopoiesis ( e.g. DNMT3A, TET2), with low VAF in almost all cases. All 35 patients with at least one mutation involving the JAK/STAT pathway belonged to the experimental group, among whom all 22 patients treated with steroids were refractory to therapy. Eighteen patients had STAT5B mutations, including 13 (72%) with the somatic N642H mutational hotspot. Two patients harbored JAK2Ex13InDel mutations, including one with eosinophilia and erythrocytosis. Previously unreported molecular alterations were also evidenced, including seven patients with JAK1 mutations and three STAT5A-mutated patients who shared common features i.e. the co-occurrence of BCOR mutations, high hemoglobin levels and eosinophil hyperplasia. Of note, the latter mutations were not reported both in a public database (GnomAD) as well as in a second cohort of 613 samples referred for suspicion of myeloid malignancies (yet without HE) studied with the same NGS workflow, thereby strongly supporting their association with myeloid HES. Deciphering the data from bulk sequencing also suggests that JAK-STAT mutations were frequently preceded by (or associated with) myelodysplasia-related gene mutations, with SF3B1 (12/36) and ASXL1 (10/36) mutations being the most common. Overall, both KIT D816V (n=2) and RAS/MAPK pathway activation mutations (n=3) were rare. No mutation of either PDGFRA/B, FGFR1 or IL3/IL5/GM-CSF-receptor genes was evidenced.In the experimental group, 17/18 (94%) patients (including 12 with JAK-STAT mutations) treated with ruxolitinib and with > 3 months of follow-up responded to treatment (12 complete and 5 partial hematological responses). Discussion. These dataemphasize the usefulness of NGS in daily practice for the workup of fusion-free HES patients harboring features suggestive of myeloid neoplasms. In such patients, druggable mutations involving the JAK-STAT pathway (including yet unidentified STAT5A mutations) are frequent. Most JAK/STAT mutations occur in the setting of a preexisting myelodysplastic or myelodysplastic/myeloproliferative disease harboring mutations in RNA-splicing genes or chromatin modifiers. These findings provide a rationale for refining treatment algorithms in fusion-free myeloid HES patients, supporting the use of JAK inhibitors as frontline therapy. More data are warranted to assess whether JAK inhibition enables sustained molecular remission in all disease subtypes.

Efficacy and Safety of Venetoclax in Combination with Azacitidine for the Treatment of Patients with Treatment-Naive, Higher-Risk Myelodysplastic Syndromes

Introduction: Azacitidine (Aza) has been shown to prolong survival in patients with treatment-naive, higher-risk myelodysplastic syndrome (HR MDS) compared to lower-intensity, conventional treatment regimens; however, improvement in clinical outcomes are needed. Clinical data on the synergy of Aza with venetoclax (Ven)-a selective, potent BCL-2 inhibitor-in the treatment of myeloid malignancies and the unmet need in HR MDS provide a rationale to evaluate Ven in combination with Aza in treatment-naive HR MDS. Here, we report efficacy and safety data in patients with treatment-naive HR MDS treated with Ven+Aza at the recommended Phase 2 dose (RP2D) in the safety expansion part of the Phase 1b study (NCT02942290). Methods: Adult patients were enrolled with de novo treatment-naive HR MDS defined by the Revised International Prognostic Scoring System (IPSS-R) score of >3 with an Eastern Cooperative Oncology Group performance status of ≤2, and bone marrow (BM) blasts <20% at baseline. Patients received Ven 400 mg orally daily on Days 1-14 and Aza 75 mg/m 2 intravenously or subcutaneously on Days 1-7 or on Days 1-5, 8, and 9 of each 28-day cycle (RP2D). The primary objective was to assess the complete remission (CR) rate. Key secondary objectives included determining marrow CR (mCR), overall response rate (ORR), hematologic improvement (HI), postbaseline red blood cell (RBC) and platelet transfusion independence (TI), overall survival (OS), duration of CR, time to next treatment (TTNT), transformation to acute myeloid leukemia (AML), and time to AML transformation. Responses were assessed by International Working Group 2006 criteria. Prophylactic antibiotics were mandated in Cycle 1 and recommended for Grade ≥3 neutropenia thereafter. Safety was analyzed in patients who received ≥1 dose of study treatment. Results: At thedata cutoff of May 31, 2023, 107 patients had received Ven+Aza at the RP2D. Key baseline characteristics for all treated patients are shown in Table 1A. Median age was 68 years (range, 26-87), 64% of patients had intermediate or poor cytogenetic risk, and >89% had ≥5% BM blasts. Median number of treatment cycles before transplantation was 3.0 (range, 1.0-11.0). At the median follow-up of 31.9 months (95% CI, 30.4-42.5), CR rate was 29.9% (95% CI, 21.4-39.5), with a median CR duration of 16.6 months (95% CI, 10.0-not reached [NR], Table 1B). Median OS was 26 months (95% CI, 18.1-51.5), with an estimated 12-month OS of 71.2% (95% CI, 61.4-78.9)and 24-month OS of 51.3% (95% CI, 41.2-60.5). Median OS for CR was NR. Median TTNT including transplantation was 6.8 months (95% CI, 5.6-8.3). Sixty-two (57.9%) patients received subsequent treatment, including transplantation in 42 (39.3%) patients; the median time to transplantation was 4.8 months (range, 1.4-16.8). Among patients who received transplantation post-study, 17 were transplant ineligible at study entry. Postbaseline TI rate was 61.7% for RBC and 72.0% for platelets. Median maximal duration of TI achieved was 5.4 months (range, 1.8-50.8) and 5.4 months (range, 1.9-56.0) for RBC and platelets, respectively. Postbaseline overall hematologic improvement (HI) was achieved in 51 (49.0%) of 104 evaluable patients, and specific responses included erythroid (40/93; 43.0%), platelet (32/74; 43.2%) and neutrophil (10/57; 17.5%) indices. All patients experienced ≥1 treatment-emergent adverse event (TEAE), with 94.4% of patients reporting grade ≥3 TEAEs. Serious adverse events (SAEs) occurred in 68.2% of patients. Common TEAEs of any grade were constipation (53.3%), nausea (49.5%), neutropenia (48.6%), thrombocytopenia (44.9%), febrile neutropenia (42.1%), diarrhea (41.1%), anemia (39.3%), vomiting (36.4%), and hypokalemia (26.2%). Grade ≥3 TEAEs reported in ≥20% of patients were neutropenia (48.6%), thrombocytopenia (43.0%), febrile neutropenia (42.1%), and anemia (34.6%). Infections were reported in 57% of patients, including SAEs in 40.2% of patients. Of the 59 deaths (55.1%) reported, 23 (21.5%) were due to disease progression and 7 (6.5%) to adverse events. Within 60 days after study start, 7 deaths (6.5%) were reported. Conclusion: Ven 400 mg for 14 days plus Aza combination was well tolerated with favorable responses of CR+PR+mCR in >80% and HI in nearly 50% of patients with treatment-naïve HR MDS. A separate Phase 3 study of this combination is ongoing to confirm survival benefit.

First-in-Human Study of the CD123 NK Cell Engager SAR443579 in Relapsed or Refractory Acute Myeloid Leukemia, B-Cell Acute Lymphoblastic Leukemia or High Risk-Myelodysplasia: Updated Safety, Efficacy, Pharmacokinetics and Pharmacodynamics

Introduction: SAR443579 (SAR'579) is a trifunctional anti-CD123 NKp46xCD16 natural killer cell engager, facilitating the formation of a cytolytic synapse between natural killer (NK)-cells and CD123-positive tumor cells leading to NK-cell activation and tumor cell killing. Herein, we report data of SAR'579 from TCD17197, an on-going phase 1/2 trial in patients (pts) with relapsed or refractory acute myeloid leukemia (R/R AML), B-cell acute lymphoblastic leukemia or high risk-myelodysplasia (HR-MDS) (NCT05086315). Methods: TCD17197 is a first-in human, open-label, multicenter study designed to characterize the overall safety and tolerability profile of SAR'579 and to assess preliminary anti-leukemic activity per International Working Group criteria. SAR'579 was administered intravenously for three 28-day induction cycles, either twice weekly or once weekly (QW), depending on the dose level (DL) for the first 2 weeks and then weekly for the remainder of the induction cycles. Pts achieving a complete remission (CR) or incomplete hematologic recovery (CRi) transitioned to maintenance with dosing approximately once every four weeks. Bone marrow and peripheral blood samples were taken at various time points to assess treatment response, pharmacokinetics, and pharmacodynamics. Results: As of July 05, 2023, 43 pts (42 R/R AML and 1 HR-MDS) across 8 DLs at 10 - 6000 µg/kg/dose (3 in DL1, 4 each in DL2 - DL5 and 8 each in DL6 - DL7 and DL1mg) were included. The median age was 68 years (21 - 81). Pts had received a median of 2.0 (1.0 -10.0) prior lines of treatment with 13 pts (30.2%) reporting prior hematopoietic stem cell transplantation and 36 pts (83.7%) withprior exposure to venetoclax. Median white blood cell count at screening was 2.8 × 10 9/L (0.2 - 12.2 × 10 9/L). Median bone marrow blast burden at study entry was 50% (2.8 - 90.0) and 7 (16.28%) pts had extramedullary disease. Pts received a median of 2 cycles (1 - 9) with a median treatment duration of 7.9 weeks (1 - 49). No dose limiting toxicities (DLTs) were observed up to the highest dose of 6000 µg/kg QW. TEAEs were reported in 42 pts (97.7%) with grade ≥3 adverse events (AEs) in 28 pts (65.1%). No TEAE lead to the permanent discontinuation of SAR'579. The most common treatment-emergent adverse events (TEAEs) were infusion-related reactions (n = 29 [67.4%]) and constipation (n = 11 [25.6%]) all being ≤ grade 2 events. Treatment-related AEs occurred in 32 pts (74.4%), with one (2.3%) grade 4 neutropenia. There were 2 cases of grade 1 cytokine release syndrome at DL4 and DL5, and no case of immune effector cell-associated neurotoxicity syndrome. The composite complete remission rate (CR+CRi) was 12.0% (5/42 R/R AML). In DLs with a highest dose of 1000 µg/kg QW, (DL3, DL4, DL1mg) 5/15 (33.3%) pts achieved a CR (4 CR/1 CRi) as of the cut-off date. Complete remissions were observed upon completion of 1 (CR & CRi), 2, 3 and 4 cycles of treatment, and the median duration of CR/CRi is not estimable. Data from updated PK/PD and in vitro mechanistic analyses studying dose-response relations will be presented. Conclusions: SAR'579 was well tolerated up to doses of 6000 µg/kg QW with observed clinical benefit in pts with R/R AML. The results are consistent with the predicted favorable safety profile.

Efficacy and safety of eltrombopag in Chinese patients with refractory or relapsed severe aplastic anemia

For patients with severe aplastic anemia (SAA) in China who have had an insufficient response to the first-line treatment with hematopoietic stem cell transplantation or immunosuppressive therapy, there is no established standard of care other than transfusion support and treatment of infections. This non-randomized, open-label, Phase II multicenter trial investigated the efficacy and safety of eltrombopag in 20 adult Chinese patients with refractory or relapsed (r/r) SAA. The primary endpoint of hematologic response rate at Week 26, defined as the proportion of patients who met any of the International Working Group criteria, was observed in 70% (14/20) of patients, with more than 50% of these having at least bi-lineage response. Reduced red blood cell and platelet transfusion at Week 26 were observed in 57% (8/14) and 80% (8/10) of patients, respectively. Safety findings were consistent with the established safety profile of eltrombopag and no new safety signals were reported. None of the patients discontinued eltrombopag because of safety concerns. Although the sample size was small, this is the first prospective study to show that eltrombopag is efficacious and has a favorable safety profile in a Chinese patient population with r/r SAA.Trial registration: This trial is registered on ClinicalTrials.gov (NCT03988608); registered 17 June 2019.

Decitabine in Combination with Aclacinomycin, Cytarabine and Granulocyte Colony-Simulating Factor (CAG) Had a High Response Rate in Children with Advanced Myelodysplastic Syndrome and Acute Myeloid Leukemia with Myelodysplasia-Related Changes

Advanced myelodysplastic syndrome (MDS) is a rare disease in children with poor prognosis. Allogeneic transplantation is the only curative option. However, there has been no established treatment prior to transplant. We conducted a retrospective study exploring the response rates and safety of decitabine combined with aclacinomycin, cytarabine and granulocyte colony-stimulating factor (CAG) for induction treatment of advanced MDS and acute myeloid leukemia with myelodysplasia-related changes (MDR-AML) in children. Patients from 1 to 14 years administrated in Pediatric Blood Disease Center of CAMS Blood Disease Hospital between January 1the 2019 and December 31th 2022 were screening. All diagnosed with MDS-EB or MDR-AML according to WHO 2016 criteria and treated with decitabine combined with CAG were identified. The efficacy of one-cycle treatment of MDS-ED was evaluated based on The International Working Group Response Criteria 2006. The response for MDR-AML was evaluated according to the criteria for AML published by ELN. The response of MDR-AML was defined as complete remission (CR) or CR with incomplete count recovery (CRi). The response of MDS-EB was defined as CR or bone marrow CR with hematological improvement (HI). A total of 13 patients, including MDS-EB (n=7) and MDR-AML (n=6), were enrolled for analysis. 5-day decitabine was administrated, combined with modified CAG regimen for 7 days. Eventually 12 patients of those were available for evaluation. For patients with MDS-EB, four achieved CR and three reached marrow CR with HI. Four patients with MDR-AML, three achieved CR and two reached CRi. The overall response rate was 100%(12/12). The most frequent adverse events were myelosuppression and suppression-induced infections, but no infection-related mortality was recorded. There had been no cardiotoxic event happened, either. Only one patient experienced fatal bleeding in early stage after treatment. The median follow-up time was 16 months (range 1-48). At last follow-up, 10 patients who had underwent allo-HCT were alive without disease. The remaining 2 patients died of disease progression. The 2-year estimated overall survival was 62.9%. Decitabine combined with modified CAG had a high response rate for children with advanced MDS and MDR-AMl, and it can bridge patients to curative allogeneic transplantation.

Phase 1/2 Study of Pacritinib in Combination with Azacitidine in Chronic Myelomonocytic Leukemia

Introduction and preclinical rationale Treatment options for chronic myelomonocytic leukemia (CMML) are limited. Hypomethylating agents (HMAs) are the only approved therapies but are associated with unsatisfactory response rates and do not impact disease evolution (Merlevede Nat Comm 2016). JAK inhibition can reduce GM-CSF signaling, which contributes to CMML pathobiology; ruxolitinib has been clinically evaluated in CMML demonstrating promising, but insufficient clinical activity. Pacritinib is a JAK inhibitor that has a unique profile which suggests it may be uniquely well suited for the treatment of CMML, including targeting of CSF1R and IRAK1, both of which are upregulated in CMML and related diseases (Obba Autophagy 2015, Rhyasen Cancer Cell 2013). Additionally, pacritinib was recently shown to be a potent inhibitor of ACVR1 (Oh AJH 2023), potentially allowing for increased iron availability and improvement in anemia. Pacritinib has been evaluated preclinically in CMML primary samples and mouse models where it demonstrated significant, albeit heterogenous activity (Yoshimi Blood 2017). To enhance the activity of pacritinib in CMML, it was also evaluated in combination with azacitidine in GM-CSF hypersensitive cell lines and primary CMML cells where profound synergy was noted (Ma ASH 2015). Based on encouraging preclinical data, we hypothesize that the combination of pacritinib with azacitidine will be an effective treatment strategy in CMML patients. Methods In this phase 1/2 trial, we will evaluate the safety and efficacy of pacritinib and azacitidine in newly diagnosed or previously treated CMML. Patients must be JAK inhibitor and HMA naïve (≤1 cycle of HMA allowed). Phase 1 will follow a ‘3+3‘ dose de-escalation design and will enroll 6-12 patients. The primary objective of this phase is to determine the recommended phase 2 dose (RP2D) of pacritinib in combination with a fixed dose of azacitidine. Pacritinib will be administered at 200mg twice daily (with a lower dose of 100mg twice daily being explored in the case of dose limiting toxicity) in combination with azacitidine 75mg/m 2 for 7 days. Phase 2 will utilize a Simon's two stage design to assess the preliminary efficacy of pacritinib in combination with azacitidine at the RP2D. In the first stage, after treating 6 patients at the RP2D, there will be an interim response assessment as part of the phase 2 portion. If at least 4 among these 6 patients show a response, the trial will proceed to a second stage and enroll an additional 12 patients. Patients will be treated for 6 cycles of 28 days each with an interim bone marrow biopsy after cycle 3. The primary endpoint of the phase 1 portion is the recommended RP2D through the assessment of dose limiting toxicities and of the phase 2 portion is the overall response rate (ORR) by the end of cycle 6 as defined by a clinical benefit or greater by myelodysplastic syndrome/myeloproliferative neoplasm International Working Group response criteria (Savona 2015). Secondary endpoints include duration of response, disease free survival, overall survival, changes in MPN-SAF total symptom scores, palpable splenomegaly, and adverse events. Several correlative studies are planned as part of this clinical trial. Modulation of biomarkers of disease activity with treatment including GM-CSF dependent STAT5 phosphorylation, MAPK, and PI3K signaling will be analyzed. We will also evaluate changes in mutational and cytogenetic burden with treatment as well as at baseline to identify predictive biomarkers of response.

Transform-1: A Randomized, Double-Blind, Placebo-Controlled, Multicenter, International Phase 3 Study of Navitoclax in Combination with Ruxolitinib Versus Ruxolitinib Plus Placebo in Patients with Untreated Myelofibrosis

Background: Janus kinase inhibitors (JAKis) provide symptom improvement and spleen volume reduction in patients with primary, post-polycythemia vera, and post-essential thrombocythemia myelofibrosis (MF). There remains a substantial unmet need for therapies that alter disease trajectory, improve outcomes, and enhance survival. The COMFORT-1 and -2 studies established JAKi monotherapy as standard-of-care with spleen volume reduction of ≥35% at Week 24 (SVR 35W24) of 42% and SVR 35W48 of 29%, respectively. In combination with the JAKi ruxolitinib, navitoclax, an orally available inhibitor of antiapoptotic B-cell lymphoma 2 proteins (BCL-X L, BCL-2, BCL-W), was shown to have pronounced antitumor activity in patients with MF in the phase 2 REFINE trial (NCT03222609). TRANSFORM-1 is an ongoing, phase 3, double-blind, placebo-controlled, multicenter, international study evaluating the safety and efficacy of navitoclax plus ruxolitinib (NAV + RUX) compared with placebo plus ruxolitinib (PBO + RUX) in JAK2i-naïve adults with MF. Methods: TRANSFORM-1 (NCT04472598) enrolled adult patients with intermediate-2 or high-risk MF with measurable splenomegaly, evidence of MF-related symptoms, no prior JAK2i treatment, and ECOG Performance Score ≤2. Patients were randomized 1:1 to receive NAV (starting dose of 200 mg [platelet {PLT} >150 × 10 9/L] or 100 mg escalated to 200 mg once daily if tolerated after ≥7 days [PLT ≤150 × 10 9/L]) or PBO, plus RUX at label dose, based on stratification factors of intermediate-2 vs high-risk MF and PLT ≤200 × 10 9/L vs >200 × 10 9/L. The primary endpoint was SVR 35W24. Secondary endpoints included change in total symptom score at Week 24 (TSS W24) assessed using 7-item MFSAF v4.0 (scale 0-70), SVR 35 at any time, duration of SVR 35, anemia response (per International Working Group criteria), reduction in marrow fibrosis, overall survival, leukemia-free survival, reduction in PROMIS Fatigue scale, and improvement in EORTC QLQ-C30 physical functioning scale. Exploratory endpoints include progression-free survival. Results: At data cutoff, April 13, 2023, 252 patients were enrolled with a median (range) follow-up of 14.9 (0.0-29.5) months; 125 patients were randomized to receive NAV + RUX and 127 to receive PBO + RUX. Most patients were male (57%), median (range) age was 69 (37-87) years, and patient demographics were similar between treatment arms ( Table 1). TRANSFORM-1 met its primary endpoint, with 79 patients (63.2%) in the NAV + RUX arm achieving SVR 35W24 compared with 40 patients (31.5%) in the PBO + RUX arm ( P<0.0001). Notably, SVR 35 at any time was achieved by 96 patients (77%) with NAV + RUX compared with 53 patients (42%) with PBO + RUX. Median (range) time to SVR 35 response was 12.3 (10.1-48.3) weeks with NAV + RUX versus 12.4 (11.3-72.3) weeks with PBO + RUX. Median duration of SVR 35 was not reached (NR) in the NAV + RUX arm compared with 19.4 months (95% CI 16.8, NR) in the PBO + RUX arm. At Week 24, the mean change in TSS from baseline was -9.7 (95% CI: -11.8, -7.6) with NAV + RUX compared with -11.1 (95% CI: -13.2, -9.1) with PBO + RUX arm ( P=0.2852). Grade ≥3 adverse events (AEs) were experienced by 85% of patients with NAV + RUX and 70% with PBO + RUX. The most common AEs (>30% of patients receiving NAV; Table 2) were thrombocytopenia, anemia, diarrhea, and neutropenia. Serious AEs were experienced by 26% of patients with NAV + RUX and 32% with PBO + RUX, including anemia (NAV + RUX: n=2; PBO + RUX: n=1), thrombocytopenia (NAV + RUX: n=2), and neutropenia (NAV + RUX: n=1). With NAV + RUX, AEs led to NAV dose reduction in 101 (81%) patients and NAV interruption in 87 (70%) patients of which 83 (67%) and 65 (52%) were due to thrombocytopenia, respectively. Of all enrolled patients, 83 (33%) discontinued study treatment; most common (>5% total patients) reason for NAV/PBO discontinuation were AEs (n=32; 39% of discontinuations) and physician decision (n=14; 17% of discontinuations). In each arm, 13 (10%) patients died; 6 with NAV + RUX and 5 with PBO + RUX died ≤30 days post-final dose. Conclusions: This first randomized trial in JAKi-naïve MF with NAV + RUX combination led to an SVR 35W24 rate that was twice as high as PBO + RUX ( P<0.0001). The responses were durable; AEs of thrombocytopenia and anemia were common but manageable with dose modification without any clinically significant sequalae. Additional evaluation is ongoing.

A Global, Phase 3, Randomized, Double-Blind Study to Evaluate Safety and Efficacy of Selinexor, an XPO-1 Inhibitor, in Combination with Ruxolitinib in JAK Inhibitor-Naïve Myelofibrosis (XPORT-MF-034)

Background and Significance: Myelofibrosis (MF) is a myeloproliferative neoplasm that commonly harbors somatic gene driver mutations in Janus kinase 2 ( JAK2), calreticulin ( CALR), and myeloproliferative leukemia virus ( MPL) genes. Selinexor is an investigational oral XPO1 inhibitor that may inhibit MF-relevant pathways including STAT, extracellular signal-regulated kinase (ERK), protein kinase B (AKT) and p53. Furthermore, in vivo preclinical studies have shown potential synergy between selinexor and ruxolitinib treatment. The Phase 3 trial was initiated based on data from the Phase 1 portion of XPORT-MF-034 evaluating the combination of selinexor and ruxolitinib in JAKi-naïve patients with MF. Previously we reported that the combination of selinexor and ruxolitinib was generally tolerable and manageable and that the 60 mg selinexor dose cohort showed 71% and 79% of the intent-to-treat (ITT) population achieving a ≥35% reduction in spleen volume from baseline (SVR35) at Week 12 and Week 24, respectively; SVR35 rates were consistent across subgroups, including gender and regardless of ruxolitinib starting dose. Robust symptom improvement was also observed with 58% of the ITT achieving a ≥50% reduction in total symptom score from baseline (TSS50) at Week 24 (Ali et al., ASCO 2023; Ali et al., AACR 2023). These data provided strong support to further evaluate selinexor (60 mg) and ruxolitinib in patients with JAKi-naïve MF. Study Design and Methods: The XPORT-MF-034 (NCT04562389) trial includes a global, Phase 3 randomized, double-blind, placebo-controlled study designed to evaluate the combination of 60 mg selinexor and ruxolitinib. Patients will be randomized 2:1 to receive oral selinexor 60 mg or placebo once weekly (28-day cycle) and twice daily ruxolitinib. Select eligibility criteria include patients ≥18 years of age, with a spleen volume of ≥450 cm 3 by MRI or CT, dynamic international prognostic scoring system (DIPSS) of intermediate-1, intermediate-2, or high-risk, active symptoms of MF as determined by presence of at least 2 symptoms with a score ≥3 or total score of ≥10 at screening using the MFSAF v4.0, currently not eligible for stem cell transplantation, ECOG PS ≤2, platelet count ≥100 x 10 9/L, and creatinine clearance >15mL/min. Patients will be excluded if more than 10% blasts are present in peripheral blood or bone marrow; received previous treatment with JAK inhibitors for MF, or previous treatment with selinexor or other XPO1 inhibitors. The co-primary study endpoints are SVR35 at Week 24 as measured by MRI or CT scan and TSS50 at Week 24 as measured by the Myelofibrosis Symptom Assessment Form (MFSAF) V4.0. The key secondary endpoint is anemia response as per the International Working Group Myeloproliferative Neoplasms Research and Treatment and European Leukemia Network (IWG-MRT and ELN) criteria at Week 24. Results: TheXPORT-MF-034 Phase 3 trial is currently open for enrollment; a total of 306 JAKi-naïve MF patients will be enrolled and the study was initiated on June 28, 2023.

A Phase 2 Study of Canakinumab in Patients with Lower-Risk Myelodysplastic Syndromes or Chronic Myelomonocytic Leukemia

Background Myelodysplastic syndromes (MDS) lie on a continuum of myeloid neoplastic progression between clonal hematopoiesis (CH) and acute myeloid leukemia (AML). Interleukin 1 beta (IL-1β)-induced inflammasome activation is a mechanism of cancer initiation and progression. Given that IL-1β upregulation induces aberrant myeloid differentiation of hematopoietic stem and progenitor cells (HSPCs), we hypothesize that IL-1β plays a critical role in MDS pathogenesis, and targeting IL-1β signaling will overcome aberrant MDS HSPCs' myeloid skewing. Here, we report final results of a phase 2 study evaluating the safety and efficacy of canakinumab, an IL-1β inhibitor, in patients with lower-risk MDS or chronic myelomonocytic leukemia (CMML). Methods We conducted a single center, open-label phase 2 trial at The University of Texas MD Anderson Cancer Center (Houston, TX, USA). Patients aged ≥ 18 with IPSS-R ≤ 3.5 MDS/CMML who have previously been treated were included in the study. Patients received 300 mg of canakinumab on day 1 of a 4-week cycle. The primary objective was to determine the clinical activity of canakinumab in MDS/CMML patients. Response was assessed using the modified International Working Group 2006 criteria for MDS (Cheson et al. 2006). Secondary objectives were to evaluate the safety profile including rate of transfusion independence (TI), duration of response (DoR), progression-free survival (PFS), and overall survival (OS). All patients who received 1 dose of study drug were included in the analyses. This study is registered with ClinicalTrials.gov (NCT04239157). Findings Between August 2020 and May 2023, 27 patients were enrolled in the phase 2 portion of this study, and 2 patients failed screening. The median age was 74 years with 15 (60%) male patients; 20 patients (80%) were post-hypomethylating agent failure with a median number of prior lines of therapy of 2 (1-5). Transfusion dependency was observed in 24 patients (96%) prior to canakinumab initiation. Fourteen (56%) patients showed normal karyotype. IPSS-R stratification revealed an intermediate-2 risk in 12 (48%) patients and a high risk in one (4%). The most common mutations were SF3B1 (40%), TET2 (32%), DNMT3A (28%), and RUNX1 (24%). IPSS -M risk score was calculated for 24 cases showing one (4%) very low (VL), four (16%) low (L), 14 (16%) moderate low (ML), eight (32%) moderate high (MH), five (20%) high (H), and two (8%) very high (VH) risk categories. Canakinumab was well tolerated and no drug-related toxicities were observed. One death due to sepsis, which was deemed not treatment-related, occurred on the study drug. Out of 23 evaluable patients, the overall response rate was 17·4%, with erythroid and platelet hematological improvement (HI-E and HI-P, respectively) confirmed in 3 (13.0%) patients and 1 (4.3%) patient, respectively. Thirteen patients had stable disease (56·5%) and 6 (26·1%) progressed during therapy, 1 of which transformed to AML (Fig. 1). TI was achieved in 3 patients (median DoR 8·53 months (95% CI 0·41-16·1) and 2 of them maintained TI for over 12 months. With a median follow-up time of 22·6 months (95% CI 15·0-29·4), median OS was 17·3 months (95% CI 14·3-not estimable). We performed separate univariate analyses to evaluate any associations between the IPSS-M and OS/PFS. The median OS in patients with higher-risk MDS by IPSS-M (MH, H, VH) was 15·0 months vs 29·4 months in the lower-risk disease by IPSS-M (VL, L, ML) group (p=0·12). Interestingly, statistically significant findings were observed with 1-year PFS when stratifying patients into higher vs lower risk MDS by IPSS-M (64·3% vs 100·0%, respectively; p=0·022, Fig. 2). Conclusion In this cohort of MDS patients who had experienced multiple lines of prior therapy and exhibited high-molecular-complexity, canakinumab showed limited efficacy (HI 17.3%). Nevertheless, canakinumab showed a good safety profile and yielded sustained long-term responses in patients with single somatic driver mutation in TET2 or DNMT3A. This suggests that clonal complexity, and therefore disease burden, may be a determining factor in response to canakinumab. Therefore, we have amended the protocol of a phase 1/2 clinical trial evaluating the safety and activity of canakinumab in clonal cytopenia of unknown significance (CCUS) and low-molecular complexity MDS patients. Our results will clarify the role of IL-1β signaling in MDS initiation and progression.

A Phase 1b Trial of DISC-0974, an Anti-Hemojuvelin Antibody, in Patients with Myelofibrosis and Anemia

Hepcidin, a central regulator of iron homeostasis, is pathologically elevated in patients with myelofibrosis (MF) and anemia. Chronic elevations in hepcidin contribute to the onset and severity of anemia. DISC-0974 is an investigational, first-in-class, monoclonal antibody that blocks hemojuvelin, a co-receptor in the bone morphogenetic protein-signaling pathway driving hepcidin expression. Preclinical studies have shown that DISC-0974 suppresses hepcidin and increases serum iron. A healthy volunteer study has demonstrated dose-dependent reductions in serum hepcidin, increases in serum iron with doses up to 56 mg administered subcutaneously, and increasing trends in reticulocyte count, reticulocyte hemoglobin, mean corpuscular hemoglobin, total hemoglobin (Hgb), and red blood cell count. In this Phase 1b/2a, open-label, multiple-ascending dose study (NCT05320198), we are assessing the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of DISC-0974 in patients with MF and anemia. Eligible participants include patients over 18 years of age with intermediate-2 or higher-risk MF and anemia. MF is required to be confirmed using the World Health Organization 2016 criteria. Anemia is defined per protocol as Hgb < 10 g/dL or transfusion dependence, as defined by the International Working Group for Myelofibrosis Research and Treatment (IWG-MRT). A stable dose of hydroxyurea and/or Janus kinase (JAK) inhibitor is allowed on trial. Major exclusion criteria include: liver iron concentration ≥ 7 mg/g dry weight; splenectomy; nutritional, genetic, infectious, or autoimmune causes of anemia. Dose escalation is based on a Bayesian optimal interval design with accelerated titration. Safety Review Committee assessments gate escalation decisions. Dosing occurs monthly for a total of 6 doses. Primary endpoints include safety and tolerability assessments of adverse events (AEs), clinical laboratory assessments, vital signs, physical examinations, and electrocardiograms. Secondary endpoints include anemia response as defined by the IWG-MRT, transfusion response as defined by a decrease of 50% in transfusion requirement over any 8-week period, standard PK parameters and PD metrics including serum hepcidin-25, iron, transferrin saturation, ferritin, and hematology biomarkers. All data are summarized using descriptive statistics. Initial data show a dose-related increase in pharmacokinetic parameters. DISC-0974 treatment led to dose-dependent reductions in serum hepcidin-25 and increases in serum iron levels. There have been no serious AEs or AEs leading to study withdrawal. Most AEs were mild, transient, and unrelated to DISC-0974. As of August 1, 2023, enrollment and dose escalation are ongoing. Safety, PK, and PD data from at least the first two cohorts will be presented.

Influence of Bone Marrow Blast Enumeration and Co-Occurring Myelodysplasia Related Gene Mutations in NPM1-Mutated Myeloid Malignancies

Introduction Both World Health Organization (WHO 5th) and International Consensus Classification (ICC) guidelines recognize mutations in nucleophosmin 1 ( NPM1mut) as a class defining molecular event in acute myeloid leukemia (AML). WHO 5th omitted the blast percentage requirement and ICC lowered the blast threshold to 10%. NPM1mut AML without FLT3 ITD or adverse risk cytogenetics is considered favorable risk in European LeukemiaNet (ELN) 2022, however co-occurring adverse-risk myelodysplasia related mutations (MR mut) do not influence ELN 2022 risk stratification. This analysis addresses the prognostic impact of blast enumeration in NPM1mut myeloid neoplasms (MN) with <10% blasts and influence of co-occurring mutations in NPM1mut AML. Methods We interrogated publicly available data from adult (≥18 years) patients (pts) with chronic myeloid neoplasms included in the International Working Group for Prognosis in MDS (N= 3,323; Bernard et al. NEJM Evid 2022) and two independent AML cohorts (AMLSG [N=1540] Papaemmanuil et al. NEJM 2016; UKNCRI [N=2,113] Tazi et al. Nat. Commun. 2022). Between group differences were assessed using the Wilcoxon rank-sum test or Fisher's exact test as appropriate. Time to event endpoints were analyzed using the log-rank method. Multivariate analysis (MVA) used cox proportional hazards regression. Results NPM1 mut was identified in 17% (N=1148) of pts (AML: 30% [1109/3653], MN with <20% blasts: 1.2% [39/3,323]). Compared to pts with NPM1mut AML, pts with NPM1mut MN (MDS, CMML, aCML) with blast < 20% were older (median age 65 vs. 55 years, p < 0.001), had a lower median total WBC count (5 vs. 32 x10 9 /L, p < 0.001) and bone marrow (BM) blast percentage (8% vs. 76%, p < 0.001). No significant difference was observed between NPM1mut AML and MN with <20% blasts in median hemoglobin (9.1 vs. 9 x10 9, p: 0.44), platelets (62 vs. 66 x10 9 /L, p: 0.55), or NPM1mut variant allele frequency (VAF; 35% vs. 37%, p: 0.64). After a median follow up of 4.7 years (range: 0-12), no difference in overall survival (OS) was observed between pts with low blast (LB; <10%) NPM1mut MN (N=19) vs. ≥10% blasts (N=18) (median OS: 0.64 years [95% CI: 0.31-3.0] vs. 1.1 years [95% CI: 0.95-NR], p=0.32). Median leukemia free survival (LFS) was 0.81 years (95% CI: 0.67-1.5) and not significantly different between NPM1mut MN pts with <10 vs. ≥10% blasts (median LFS: 0.55 vs. 0.91 years, p=0.27). In pts with NPM1mut AML (N=1109), 52% (N=581) were ELN 2022 favorable-risk; 15% (N=92) had MR mut including SRSF2 (51%, N=47), STAG2 (21%, N=19), ASXL1 (9%, N=8), BCOR (9%, N=8), RUNX1 ( 8%, N=7), EZH2 (5%, N=5), SF3B1 (5%, N=5), U2AF1 (1%, N=1), and ZRSR2 (1%, N=1). Pts with MR mut were older (median age 62 vs. 53 years, p < 0.001), had higher BM blasts (80% vs. 72% p=0.019), and lower platelets (45 vs. 77 x10 9/L p < 0.001) compared to pts with NPM1mut AML without MR mut. No significant difference in NPM1mut VAF was observed (34% in both groups). After a median follow up of 3.5 years (range: 0-15), median OS was 6.2 years in pts with NPM1mut AML (95% CI: 4.2-9.7). Inferior OS was observed in ELN favorable risk NPM1mut pts with vs. without MR mut, respectively (2 vs. 8.4 years, p=0.0001). When stratified by age < 60 vs. ≥ 60 years, younger pts with MR mut had an increased risk of death (HR 1.7 95% CI: 1.1-2.8, p: 0.02). No OS difference was observed in older pts with or without MR mut (HR: 1.2, 95% CI: 0.80-1.68, p=0.44), however OS was significantly shorter in older pts with NPM1mut compared to younger pts (median 1.7 years vs. NR, p < 0.001). Patients with NPM1mut /MR mut AML had survival comparable to patients with ELN 2022 intermediate risk AML (2.0 vs. 2.1 years, p=0.35). In MVA of NPM1mutAML adjusted for MR mut, BM blast percentage, age, performance status, baseline WBC, hemoglobin, platelet count, NPM1mut VAF, and treatment setting (AMLSG or UKNCRI), the presence of an MR mut (HR 1.39 [95% CI: 1.0-1.9], p=0.04), age < 60 (HR 0.43 [95% CI: 0.32-0.56], p < 0.001), and performance status (HR 1.35 [95% CI: 1.14-1.60], p=0.0004) retained statistical significance. Conclusion Pts with low blast NPM1mut MN have outcomes similar to pts with NPM1mut AML, supporting NPM1mut as an AML defining event irrespective of BM blast enumeration. In patients with ELN favorable risk NPM1mut AML, co-occurrence of MR mut is independently associated with inferior survival, comparable to ELN intermediate risk AML. These results may inform future refinements of current consensus guidelines.

Development, Evaluation, and impLemenTation for guideline adaptation: a quality improvement protocol for the DELTA study in global health practice.

Guideline adaptation is an emerging field to provide more appropriate recommendations for local clinical practice quality and to promote global health equity. However, its utilization status, adaptation procedures, and related materials remain to be studied. This study developed a quality improvement protocol for a study as the Development, Evaluation, and impLemenTation for guideline Adaptation (DELTA) study. Current adapted clinical practice guidelines (CPGs) will be systematically searched. Their characteristics, utilization status, and adaptation procedures will be extracted, compared, and analyzed. Whether these adapted CPGs rigorously followed the instruments and steps of adaptation frameworks will also be appraised. In addition, the advantages and limitations of current adaptation methods and their suitable application situations will be analyzed. In addition, future perspectives as DELTA series and DELTA system, aiming for comprehensively evaluating current needs for guideline adaptation and developing a unified framework and related materials were proposed to improve the acceptability, applicability, and implementation of guideline adaptation in clinical practice. The DELTA series are divided into four phases: phase I in analyzing status, characteristics, and procedures and completeness of adapted CPGs; phase II in analyzing differences, heterogeneity, and implementation between adapted and original CPGs; and phase III in collecting, analyzing, and comparing all available adaptation materials. With these research bases, an international working group will be established in phase IV and will develop unified guideline adaptation materials after Delphi consensus, including adaptation frameworks, appraisal tools and checklists, registries, and databases. Guideline adaptation has been advanced as an efficient way to guide local clinical practice. However, it still faces several major challenges. The proposed DELTA study, series, and system will further contribute to this emerging topic. This study has been registered by the PROSPERO international database. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=400170 .

Rationale for the Development of a Novel Clinical Grading Scale for Postoperative Facial Nerve Function: Results of a Multidisciplinary International Working Group.

The objective of the current study was to present the results of an international working group survey identifying perceived limitations of existing facial nerve grading scales to inform the development of a novel grading scale for assessing early postoperative facial paralysis that incorporates regional scoring and is anchored in recovery prognosis and risk of associated complications. Survey. A working group of 48 multidisciplinary clinicians with expertise in skull base, cerebellopontine angle, temporal bone, or parotid gland surgery. House-Brackmann grade is the most widely used system to assess facial nerve function among working group members (81%), although more than half (54%) agreed that the system they currently use does not adequately estimate the risk of associated complications, such as corneal injury, and confidence in interrater and intrarater reliability is generally low. Simplicity was ranked as the most important attribute of a novel postoperative facial nerve grading system to increase the likelihood of adoption, followed by reliability and accuracy. There was widespread consensus (91%) that the eye is the most critical facial region to focus on in the early postoperative setting. Members were invited to submit proposed grading systems in alignment with the objectives of the working group for subsequent validation. From these data, we plan to develop a simple, clinically anchored, and reproducible staging system with regional scoring for assessing early postoperative facial nerve function after surgery of the skull base, cerebellopontine angle, temporal bone, or parotid gland.