Chronic Myelomonocytic Leukemia Research Articles

Phase 1 study to determine the safety and efficacy of onvansertib, a novel, oral, PLK1 inhibitor in patients with proliferative chronic myelomonocytic leukemia relapsed/refractory or intolerant to available therapies.

TPS7089 Background: Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative overlap neoplasm (MDS/MPN) that can be further divided into MD (WBC < 13 x 109/L) and MP (≥13 x 109/L) subtypes. MP-CMML is enriched in RAS pathway mutations ( NRAS, CBL, KRAS, PTPN11 and NF1), has a shorter median survival (19 vs 36 months), has a higher rate of acute myeloid leukemia (AML) transformation (40% vs 10%) and has a unique transcriptomic and epigenetic composition. These RAS pathway mutations promote selective PLK1 overexpression, a mitotic checkpoint kinase. Given the relative inefficacy of hypomethylating agents (HMA) in MP-CMML and previously demonstrated in vitro and in vivo efficacy data for PLK1 inhibition on MP-CMML with RAS pathway mutations, we designed a phase 1 clinical trial testing the safety of onvansertib, a novel, orally bioavailable, PLK1 inhibitor in relapsed/refractory MP-CMML. Methods: This is an investigator-initiated, prospective, open-label, phase I study of onvansertib in MP-CMML relapsed/refractory (RR) or intolerant to existing therapies including HMA and hydroxyurea. The primary endpoint is characterization of safety. Secondary endpoints include efficacy as defined by the 2015 MDS/MPN International Working Group criteria, volumetric spleen response and symptom response via assessment with MPN-SAF-TSS. Inclusion criteria include MP-CMML RR following hydroxyurea or at least 4-cycles of HMA or intolerance of treatment with either, platelets ≥ 20,000/m3 and Cockcroft-Gault creatinine clearance ≥ 60 mL/min/m2. Hydroxyurea may continue for the first 28 days on study. Onvansertib will be given orally on days 1 through 21 of a 28-day cycle with a Bayesian optimal interval design to assess the safety and recommended phase II dose. Exploratory end points include targeting efficacy, impact of PLK1 and KMT2A expression and interactions with ASXL1 and TET2 mutations. Twenty-five patients will be enrolled at Mayo Clinic in Minnesota, with enrollment open since November 2022. Clinical trial information: NCT05549661 .

Real-world (RW) treatment (tx) patterns of patients (pts) with higher-risk myelodysplastic syndrome (MDS) in a US RWE database (COTA).

e19077 Background: Pts with higher-risk MDS have poor outcomes. To understand current tx patterns/identify unmet needs, the COTA database, using pt-level curated electronic health record (EHR) data from centers across the US, was analyzed. Methods: This was a retrospective, descriptive analysis of deidentified secondary data from the COTA MDS RWE database. Data were abstracted from EHRs using these criteria: inclusion of adults with IPSS-R intermediate (I)/high (H)/very high-risk (vHR) MDS on/after 1/1/2012, exclusion of pts with no diagnosis date/clinician notes or pts with concurrent malignancies. Follow-up was until the last recorded event (last visit/other cancer/death; data cutoff 06/2022). Results: Data from 640 pts were included in this analysis. See Table for baseline demographic data. Most pts with IR- (225/281, 80%) and HR-MDS (162/239, 68%) were treated at community centers; pts with vHR-MDS were equally treated at academic (59/120, 49%) and community centers (61/120, 51%). Genetic/molecular data were limited; among pts with data available, the most common genetic mutation was TP53 (75/215, 35%). Of 640 pts, 108 (17%) did not receive tx and 110 (17%) received allogeneic stem cell transplant (alloSCT). Of those given systemic tx, hypomethylating agents (HMAs) were the most common first-line tx (444/532, 83%). Venetoclax was given to 35/640 pts (5%; as first line: 10/532, 2%; as second line: 20/170, 12%; as third line: 4/66, 6%). Median time to start tx from diagnosis was 2.2, 1.1, and 0.9 mo for IR-, HR-, and vHR-MDS, respectively. Of 512 pts assessed for first-line tx with duration data, tx duration was 7.4, 5.4, and 4.2 mo for IR-, HR-, and vHR-MDS, respectively. In 340 pts—including pts who underwent alloSCT—with response data, pts with IR-, HR-, and vHR-MDS had RW response rates (any response) of 73%, 72%, and 58%, respectively. Median OS (mOS) from start of tx was 29.0, 20.3, and 11.9 mo for IR-, HR-, and vHR-MDS, respectively. mOS (from tx start) according to tx: alloSCT 31.4 mo, chemotherapy 19.1 mo, HMAs 23.1 mo, investigational 22.1 mo, venetoclax 10.1 mo, and others 23.8 mo. About 20% of pts transformed into acute myeloid leukemia, chronic myeloid leukemia, chronic myelomonocytic leukemia, or chronic lymphocytic leukemia. Conclusions: This RW study showed that available tx for pts with higher-risk MDS in the US is limited and remains a high unmet need. [Table: see text]

Implementing a germline testing program using fingernail specimens for patients with hematologic malignancies and initial clinical findings.

10632 Background: About 5-20% of hematologic malignancies (HM) occur in the setting of a genetic cancer predisposition syndrome. Additionally, overt constitutional syndromes involving multiple systems may also predispose to HM. The spectrum of cancer predisposition in patients with HM has been limited partially due to the difficulty of germline sample ascertainment from patients with liquid tumors as skin biopsies and fibroblast cultures are often required for testing. Methods: Hematologic malignancy patients enrolled in Memorial Sloan Kettering Cancer Center’s institutional 12-245 study who were having somatic testing performed on their tumor were given the option to consent to germline testing using fingernail specimens. The validated germline assay using nails as a sample type was approved as a clinical test by the New York State Department of Health. Samples were analyzed using a custom panel consisting of 82 cancer predisposition genes. Single nucleotides, insertions deletions, and copy number variants were detected using our analytic pipeline and analyzed according to ACMG criteria for pathogenicity. Only pathogenic and likely pathogenic germline variants (gPV) were returned. Results: Among 86 HM patients (acute myeloid leukemia, n = 19; myelodysplastic syndrome, n = 16; acute B lymphoblastic leukemia, n = 9; acute T-cell leukemia, n = 4; mixed phenotypic acute leukemia, n = 1; chronic lymphocytic leukemia, n = 7; hairy cell leukemia, n = 1; chronic myeloid leukemia, n = 4; chronic myelomonocytic leukemia, n = 1, non-Hodgkin lymphoma, n = 12; Hodgkin lymphoma, n = 8; and multiple myeloma, n = 4), gPV were detected in 16 % (14/86). Heterozygous gPV identified in high/moderate penetrant genes included 2 BRCA1, 2 ATM, 1 PALB2, and 3 CHEK2. Monoallelic carriers for homozygous disease included 2 MUTYH and 1 MSH3. Biallelic gPV were identified in 3 patients (1 FANCA, 1 ATM, 1 MSH6); the patients with Fanconi anemia (age 25) manifesting with MDS and constitutional mismatch repair deficiency (age 13) presenting with T-cell lymphoblastic lymphoma had not been previously diagnosed with these conditions and did not have obvious clinical features outside of their cancer diagnosis. In all 3 patients, identification of an autosomal recessive syndrome impacted therapeutic planning. Conclusions: Our study demonstrates the feasibility of utilizing nails, a non-contaminated germline sample source, for HM predisposition with a significant proportion of pediatric and adult HM patients identified to harbor gPV in a cancer predisposition gene. Autosomal recessive diseases should be considered not only in pediatrics but also adult patients and requires confirmation of allele segregation in parents. Our data also demonstrate the importance of gPV in HM for therapeutic planning.

Sabatolimab (MBG453) model-informed drug development for dose selection in patients with myelodysplastic syndrome/acute myeloid leukemia and solid tumors.

Sabatolimab is a novel immunotherapy with immuno-myeloid activity that targets T-cell immunoglobulin domain and mucin domain-3 (TIM-3) on immune cells and leukemic blasts. It is being evaluated for the treatment of myeloid malignancies in the STIMULUS clinical trial program. The objective of this analysis was to support the sabatolimab dose-regimen selection in hematologic malignancies. A population pharmacokinetic (PopPK) model was fit to patients with solid tumors and hematologic malignancies, which included acute myeloid leukemia, myelodysplastic syndrome (including intermediate-, high-, and very high-risk per Revised International Prognostic Scoring System), and chronic myelomonocytic leukemia. The PopPK model, together with a predictive model of sabatolimab distribution to the bone marrow and binding to TIM-3 was used to predict membrane-bound TIM-3 bone marrow occupancy. In addition, the total soluble TIM-3 (sTIM-3) kinetics and the pharmacokinetic (PK) exposure-response relationship in patients with hematologic malignancies were examined. At intravenous doses above 240 mg Q2w and 800 mg Q4w, we observed linear PK, a plateau in the accumulation of total sTIM-3, and a flat exposure-response relationship for both safety and efficacy. In addition, the model predicted membrane-bound TIM-3 occupancy in the bone marrow was above 95% in over 95% of patients. Therefore, these results support the selection of the 400 mg Q2w and 800 mg Q4w dosing regimens for the STIMULUS clinical trial program.

Low Incidence of Relapse with a Moderate Conditioning Regimen of Fludarabine, Busulfan, and Melphalan for Patients with Myeloid Malignancies: A Single-Center Analysis of 100 Patients

Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) with standard myeloablative conditioning regimens such as Flu-Bu (fludarabine and busulfan) remains a major concern in patients with myeloid malignancies. A low relapse rate was reported when thiotepa or melphalan (Mel) were added to Flu-Bu, but this might increase the non-relapse mortality (NRM). Here, we evaluated the outcomes of 100 patients (70 acute myeloid leukemia, 23 myelodysplastic syndrome, 4 chronic myelomonocytic leukemia, and 3 granulocytic sarcoma) who received their first allo-HSCT after moderate-dose FBM conditioning regimen (fludarabine 150 mg/m2, busulfan 6.4 mg/kg, and melphalan 140 mg/m2, n=69; or lower-dose melphalan at 100 mg/m2 for patients over 55 years old and/or those with HCT-CI ≥3, n=31). The donors were HLA-matched siblings (n=19), unrelated donors (n=4), and haplo-identical donors (n=77). A total of 88% patients had an intermediate or high disease risk index (DRI). Out of 96 evaluable patients, 94 achieved neutrophil engraftment and had full donor chimerism on day 30. After a median follow-up of 468 days (range, 55-1039 days), only four patients relapsed with 2-year cumulative incidence of relapse (CIR) of 5.3%±3.6%. The 100-day and 2-year NRM were 6.8%±4.4% and 12.3%±3.6%, respectively. At last follow-up, the 2-year disease-free survival (DFS) and overall survival (OS) were 82.4%±4.2% and 80.3%±6.0%, respectively. Moreover, when comparing the transplantation outcomes between patients with melphalan 100 mg/m2 and 140 mg/m2, the NRM and CIR were not significantly different and the 2-year DFS and OS were similar in both groups, although the Mel 100 group was associated with a higher median age (58 vs 42 years, p<0.001) and a higher percentage of patients with HCT-CI ≥3 (p=0.005). For the whole group, the only independent factor associated with transplantation outcomes was HCT-CI ≥3, which led to higher NRM and inferior DFS and OS. Our study suggested that moderate-intensity FBM conditioning was feasible for patients with myeloid malignancies with a low relapse rate without increased NRM. A lower dose of melphalan at 100 mg/m2 maintained the low relapse risk without excess NRM for older adults. However, the FBM regimen should be used with caution in patients with high-risk HCT-CI (≥3).

CPX-351 in higher risk myelodysplastic syndrome and chronic myelomonocytic leukaemia: a multicentre, single-arm, phase 2 study

CPX-351, an encapsulated form of cytarabine and daunorubicin, has shown greater efficacy than the classic 3 + 7 treatment administration in secondary acute myeloid leukaemia. Given that higher-risk myelodysplastic syndrome and chronic myelomonocytic leukaemia share similarities with secondary acute myeloid leukaemia, we aimed to investigate the safety and efficacy of CPX-351 in this context. This investigator-initiated two-cohort phase 2 trial was conducted by the Groupe Francophone des Myélodysplasies, with 12 participating centres in France. It comprised cohort A (reported here and completed), which included patients in first-line treatment, and cohort B, which was stopped for lack of inclusion (ie, not enough patients met the inclusion criteria), for patients with hypomethylating agent failure that is not reported here. Cohort A enrolled patients with newly diagnosed higher-risk myelodysplastic syndrome or chronic myelomonocytic leukaemia (aged 18-70 years old) with an Eastern Cooperative Oncology Group performance status of 0-1. Intravenous CPX-351 (100 mg/m2 cytarabine and 44 mg/m2 daunorubicin) was given on days 1, 3, and 5, with a second induction cycle given (same daily dose on days 1 and 3) if at least a partial response was not reached. Patients who responded could receive up to four monthly consolidation cycles (same daily dose on day 1) or allogeneic haematopoietic stem-cell transplantation (HSCT). Overall response rate after one or two induction courses according to European LeukemiaNet 2017 acute myeloid leukaemia was the primary endpoint after CPX-351 induction, whether patients received one or two induction cycles. Safety was assessed in all patients enrolled (in cohort A). This trial is registered with ClinicalTrials.gov, NCT04273802. Between April 29, 2020, and Feb 10, 2021, 21 (68%) male and ten (32%) female patients were enrolled. 27 (87%) of 31 patients responded (95% CI 70-96). 16 (52%) of the 31 patients received at least one consolidation cycle. 30 (97%) of the 31 patients included were initially considered eligible for allogeneic HSCT and 29 (94%) of the 31 patients had the procedure. Median follow-up was 16·1 months (IQR 8·3-18·1). The most common grade 3-4 adverse events were pulmonary (eight [26%] of 31 patients) and cardiovascular (six [19%] of 31 patients). There were 14 serious adverse events (mainly hospitalisation for infection [n=5] and only one was treatment-related) and no treatment-related death. CPX-351 appears to be active and safe in patients with higher-risk myelodysplastic syndrome and chronic myelomonocytic leukaemia, allowing bridging to allogenic HSCT in most patients. Jazz Pharmaceuticals.

CPX-351 for higher risk myelodysplastic syndrome: cytarabine and daunorubicin in disguise?

Higher-risk myelodysplastic syndrome is a heterogenous disease with a poor prognosis that occurs in older people. 1 Greenberg PL Myelodysplastic syndromes, thy name is heterogeneity. Br J Haematol. 2023; 201: 381-382 Crossref PubMed Scopus (0) Google Scholar Current treatment regimens usually result in a transient and often less than complete response. Only allogeneic haematopoietic stem-cell transplantation (HSCT) can potentially cure a select group of relatively young and fit patients. These patients usually receive remission induction therapy before allogeneic HSCT, but in the absence of well designed, prospective randomised clinical trials, its value remains uncertain. 2 de Witte T Bowen D Robin M et al. Allogeneic hematopoietic stem cell transplantation for MDS and CMML: recommendations from an international expert panel. Blood. 2017; 129: 1753-1762 Crossref PubMed Scopus (213) Google Scholar CPX-351 in higher risk myelodysplastic syndrome and chronic myelomonocytic leukaemia: a multicentre, single-arm, phase 2 studyCPX-351 appears to be active and safe in patients with higher-risk myelodysplastic syndrome and chronic myelomonocytic leukaemia, allowing bridging to allogenic HSCT in most patients. Full-Text PDF

Targeting BET Proteins Downregulates miR-33a To Promote Synergy with PIM Inhibitors in CMML.

Preclinical studies in myeloid neoplasms have demonstrated efficacy of bromodomain and extra-terminal protein inhibitors (BETi). However, BETi demonstrates poor single-agent activity in clinical trials. Several studies suggest that combination with other anticancer inhibitors may enhance the efficacy of BETi. To nominate BETi combination therapies for myeloid neoplasms, we used a chemical screen with therapies currently in clinical cancer development and validated this screen using a panel of myeloid cell line, heterotopic cell line models, and patient-derived xenograft models of disease. We used standard protein and RNA assays to determine the mechanism responsible for synergy in our disease models. We identified PIM inhibitors (PIMi) as therapeutically synergistic with BETi in myeloid leukemia models. Mechanistically, we show that PIM kinase is increased after BETi treatment, and that PIM kinase upregulation is sufficient to induce persistence to BETi and sensitize cells to PIMi. Furthermore, we demonstrate that miR-33a downregulation is the underlying mechanism driving PIM1 upregulation. We also show that GM-CSF hypersensitivity, a hallmark of chronic myelomonocytic leukemia (CMML), represents a molecular signature for sensitivity to combination therapy. Inhibition of PIM kinases is a potential novel strategy for overcoming BETi persistence in myeloid neoplasms. Our data support further clinical investigation of this combination.

Clinicopathologic Spectrum of Lysozyme-Associated Nephropathy

Lysozyme-associated nephropathy (LyN), a rare cause of kidney injury in patients with chronic myelomonocytic leukemia (CMML), has not been well described to date. We report the clinicopathologic spectrum of LyN from a multi-institutional series. We identified 37 native kidney biopsies with LyN and retrospectively obtained clinicopathologic data. Thirty-seven patients had a median age of 74 years and included 78% males. Their most common presentation was acute kidney injury (AKI) or AKI on chronic kidney disease (CKD) (66%) with median estimated glomerular filtration rate (eGFR) of 21.7 ml/min per 1.73 m2, and proteinuria of 1.7 g. A minority (15%) had partial Fanconi syndrome. Serum lysozyme levels were elevated in all tested. Hematologic disorder (n= 28, 76%) was the most common etiology, including CMML (n= 15), acute myeloid leukemia (n= 5), and myelodysplastic syndrome (MDS) (n= 5). Nonhematologic causes (n= 5, 14%), included metastatic neuroendocrine carcinoma (n= 3), sarcoidosis, and leprosy. Etiology was unknown in 4 (11%). Pathology showed proximal tubulopathy with abundant hypereosinophilic intracytoplasmic inclusions, with characteristic staining pattern by lysozyme immunostain. Mortality was high (8/30). However, among the 22 alive, including 85% treated, 7 had improved kidney function, including 1 who discontinued dialysis and 6 with increase in eGFR >15 ml/min per 1.73 m2 compared with eGFR at the time of biopsy. Increased awareness of the full clinicopathologic spectrum of LyN may lead to prompt diagnosis, earlier treatment, and potentially improved outcome of this rare entity.

Molecular features of 109 patients with chronic myelomonocytic leukemia in a single center

Objective: To explore the molecular features of chronic myelomonocytic leukemia (CMML) . Methods: According to 2022 World Health Organization (WHO 2022) classification, 113 CMML patients and 840 myelodysplastic syndrome (MDS) patients from March 2016 to October 2021 were reclassified, and the clinical and molecular features of CMML patients were analyzed. Results: Among 113 CMML patients, 23 (20.4%) were re-diagnosed as acute myeloid leukemia (AML), including 18 AML with NPM1 mutation, 3 AML with KMT2A rearrangement, and 2 AML with MECOM rearrangement. The remaining 90 patients met the WHO 2022 CMML criteria. In addition, 19 of 840 (2.3%) MDS patients met the WHO 2022 CMML criteria. At least one gene mutation was detected in 99% of CMML patients, and the median number of mutations was 4. The genes with mutation frequency ≥ 10% were: ASXL1 (48%), NRAS (34%), RUNX1 (33%), TET2 (28%), U2AF1 (23%), SRSF2 (21.1%), SETBP1 (20%), KRAS (17%), CBL (15.6%) and DNMT3A (11%). Paired analysis showed that SRSF2 was frequently co-mutated with ASXL1 (OR=4.129, 95% CI 1.481-11.510, Q=0.007) and TET2 (OR=5.276, 95% CI 1.979-14.065, Q=0.001). SRSF2 and TET2 frequently occurred in elderly (≥60 years) patients with myeloproliferative CMML (MP-CMML). U2AF1 mutations were often mutually exclusive with TET2 (OR=0.174, 95% CI 0.038-0.791, Q=0.024), and were common in younger (<60 years) patients with myelodysplastic CMML (MD-CMML). Compared with patients with absolute monocyte count (AMoC) ≥1×10(9)/L and <1×10(9)/L, the former had a higher median age of onset (60 years old vs 47 years old, P<0.001), white blood cell count (15.9×10(9)/L vs 4.4×10(9)/L, P<0.001), proportion of monocytes (21.5% vs 15%, P=0.001), and hemoglobin level (86 g/L vs 74 g/L, P=0.014). TET2 mutations (P=0.021) and SRSF2 mutations (P=0.011) were more common in patients with AMoC≥1×10(9)/L, whereas U2AF1 mutations (P<0.001) were more common in patients with AMoC<1×10(9)/L. There was no significant difference in the frequency of other gene mutations between the two groups. Conclusion: According to WHO 2022 classification, nearly 20% of CMML patients had AMoC<1×10(9)/L at the time of diagnosis, and MD-CMML and MP-CMML had different molecular features.

P122 - Topic: AS07-Singular Entities/Subtypes/AS07e-Chronic myelomonocytic leukemia and overlap syndromes (MDS/MPN): TET2/SRSF2 STATUS AND THROMBOSIS ARE RELEVANT FOR PROGNOSIS IN CHRONIC MYELOMONOCYTIC LEUKEMIA –DATA FROM A POPULATION-BASED STUDY OF 155 PATIENTS

P122 - Topic: AS07-Singular Entities/Subtypes/AS07e-Chronic myelomonocytic leukemia and overlap syndromes (MDS/MPN): TET2/SRSF2 STATUS AND THROMBOSIS ARE RELEVANT FOR PROGNOSIS IN CHRONIC MYELOMONOCYTIC LEUKEMIA –DATA FROM A POPULATION-BASED STUDY OF 155 PATIENTS

Abstract PR02: RSK1 targeting impedes oncogenic driver and inflammatory cytokine signaling to attenuate myeloid neoplasms

Abstract Myeloproliferative neoplasms (MPNs), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML) exist among a spectrum of myeloid malignancies, governed by critical genetic dependencies, and propagated by a ripe pro-inflammatory niche. We previously identified elevated RPS6KA1 (RSK1) expression in myeloid malignancies associated with poor overall survival. Here, we demonstrate that RSK1 plays a fundamental role in mediating inflammation and serves as a central signaling node driving leukemogenesis. We further evaluate a novel therapeutic regimen utilizing a first-in-class RSK1 inhibitor, PMD-026, currently evaluated in Phase 1/1b clinical trials for breast cancer, for use in myeloid malignancies. Plasma analysis of 144 MPN patients and RNA-seq of CD14+ monocytes from 54 MPN patients revealed enrichment of inflammatory cytokines and hyperactive NFκB signaling. RSK1 inhibition by shRNA or PMD-026 in THP-1 monocytic AML cells potently suppressed this NFκB node, decreased TNF and NFKB1 mRNA, and reduced luminescence in cells expressing a NFκB-luciferase reporter. Immunoblotting and cytokine mass cytometry revealed suppression of RelA/p65 phosphorylation with reduction of TNF, IL-6, IL-8, CCL3, and CCL4 in MPN and CMML CD14+ monocytes. We also observed that RSK1 inhibition attenuated NFκB activation by TNF, LPS, and Pam3CSK4, while also suppressing monocyte differentiation to M1 macrophages. In the MPL W515L myelofibrosis (MF) model, mice treated with PMD-026 had significant reduction in TNF, IL-6, IL-1b, CCL3, and CCL5 by multiplex cytokine profiling and diminished disease burden (reduction of leukocytosis, splenomegaly, and bone marrow fibrosis). Finally, amelioration of disease was observed across MF and sAML patient-derived xenograft (PDX) models with PMD-026 treatment. We extended our findings to FLT3-ITD de novo AML models, in which RSK1 inhibition led to lethality in FLT3-ITD cells and PMD-026 potently suppressed leukemic engraftment in a MV4-11 mouse xenograft. Both genetic and pharmacological inhibition of RSK1 reduced FLT3 phosphorylation and revealed a novel, bi-directional regulatory network. Moreover, we found that RSK1 perturbation also attenuated FLT3 expression and altered protein stability, which was not observed with FLT3 inhibitor quizartinib. Mechanistically, RSK1 modulated FLT3 dynamics through deubiquitinase USP1, which was downregulated upon RSK1 perturbation. USP1 perturbation led to cell death and phenocopied FLT3 suppression observed with RSK1 inhibition. We further identified elevated USP1 expression associated with worse survival outcomes across the TCGA LAML, BeatAML, and Leucegene cohorts, thus indicating the potential of USP1 as a novel biomarker. We uncover a role for targeting RSK1 as a two-pronged approach in reducing disease burden across myeloid malignancies via: 1) suppressing driver signaling, and 2) dampening the pro-inflammatory milieu. These findings highlight a critical dependency along the RSK1-USP1-FLT3 axis that is potentially exploitable with RSK1 inhibitors such as PMD-026. Citation Format: Tim Kong, Angelo Laranjeira, Stephen Oh. RSK1 targeting impedes oncogenic driver and inflammatory cytokine signaling to attenuate myeloid neoplasms [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr PR02.

Genomics of myelodysplastic/myeloproliferative neoplasm.

Myelodysplastic/ Myeloproliferative neoplasms (MDS/MPN) demonstrate overlapping pathologic and molecular features of myelodysplastic (MDS) and myeloproliferative (MPN) neoplasms. Diagnosis is difficult based on morphology alone, requiring exclusion of various non-neoplastic causes for CBC abnormalities and morphologic findings and other myeloid neoplasms. Identifying a clonal abnormality by cytogenetics or molecular studies has vastly improved our ability to diagnose MDS/MPN and has been incorporated in the different classification schemas. Currently two separate classification systems are in use- The 5th edition WHO and international consensus classification. The two competing classifications emphasize genetic work-up and are similar on many levels; however, they do introduce diagnostic dilemma when diagnosing certain entities such as chronic myelomonocytic leukemia in the presence of NPM1 mutations. The genetic profile overlaps among different subentities; however, the combination and the incidence of mutations; together with the clinical features and morphology helps in further subclassification. In this review, we discuss the advances in molecular characterization of MDS/MPN. We attempt to summarize the differences between the various classification schemes, and highlight the changes made in the diagnostic criteria.

P096 - Topic: AS06-Prognosis/AS06a-Prognostic factors of outcome and risk assessment: GENOMIC DETERMINANTS OF DYSMYELOPOIESIS AND EVALUATION OF ITS PROGNOSTIC IMPACT IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML)

P096 - Topic: AS06-Prognosis/AS06a-Prognostic factors of outcome and risk assessment: GENOMIC DETERMINANTS OF DYSMYELOPOIESIS AND EVALUATION OF ITS PROGNOSTIC IMPACT IN CHRONIC MYELOMONOCYTIC LEUKEMIA (CMML)

P120 - Topic: AS07-Singular Entities/Subtypes/AS07e-Chronic myelomonocytic leukemia and overlap syndromes (MDS/MPN): CLINICO-BIOLOGICAL CHARACTERISTICS AND OUTCOME OF 313 CHRONIC MYELOMONOCYTIC LEUKEMIA PATIENTS INCLUDING 104 FORMERLY REFERRED TO AS OLIGOMONOCYTIC

P120 - Topic: AS07-Singular Entities/Subtypes/AS07e-Chronic myelomonocytic leukemia and overlap syndromes (MDS/MPN): CLINICO-BIOLOGICAL CHARACTERISTICS AND OUTCOME OF 313 CHRONIC MYELOMONOCYTIC LEUKEMIA PATIENTS INCLUDING 104 FORMERLY REFERRED TO AS OLIGOMONOCYTIC

Plasmacytoid dendritic cell neoplasms.

Plasmacytoid dendritic cells (pDCs) are type I interferon-producing cells that modulate immune responses. There are two types of pDC neoplasms: 1) mature pDC proliferation (MPDCP) associated with myeloid neoplasm and 2) blastic pDC neoplasm (BPDCN). MPDCP is a clonal expansion of mature pDCs that is predominantly associated with chronic myelomonocytic leukemia. In contrast, BPDCN is a clinically aggressive myeloid malignancy involving the skin, bone marrow, lymphatic organs, and central nervous system. There are various types of skin lesions, ranging from solitary brown or violaceous to disseminated cutaneous lesions, which often spread throughout the body. The expression of CD4, CD56, CD123, and pDC markers (TCL-1, TCF4, CD303, and CD304, etc.) are typical immunophenotype of BPDCN. Historically, BPDCN treatment has been based on acute leukemia regimens and allogeneic hematopoietic cell transplantation in selected patients. Recent advances in molecular biology and genetics have led to the development of targeted agents, such as tagraxofusp (a recombinant fusion protein targeting CD123), anti-CD123 CAR-T cells, XmAb14045, and IMGN632. Lastly, this review provides a comprehensive overview of pDC neoplasms.

An Assessment of the Three Popular Prognostic Scoring Systems for Chronic Myelomonocytic Leukemia (CMML) in an Indian Context

Abstract Introduction: Chronic myelomonocytic leukemia (CMML) is a rare clonal hematopoietic neoplasm with a prevalence of 1.05 to 1.94 cases per 1,00,000 population. There are multiple prognostic scoring system used in practice for CMML, which include both cytogenetic and next-generation sequencing based. Objective This study assesses the clinicohematological profile of CMML patients, along with comparison of three widely used prognostic scoring systems for CMML (CMML-specific prognostic scoring system, MD Anderson prognostic score, Mayo prognostic model). Materials and Methods: This study is an 8-year retrospective study. All relevant data had been retrieved and reviewed by the authors. Inclusion and exclusion criteria: All the cases that were diagnosed before 2016 as per 2008 criteria were reclassified, (2) all the cases that were positive for the mutations associated with myeloproliferative neoplasms were excluded, and (3) cases with more than or equal to 20% blast/blast equivalents were excluded. A univariate analysis was done followed by a multivariate analysis for all the parameters constituting each scoring system. Lastly, a receiver operating characteristic curve was plotted for all the three scoring systems. Result: There were total 23 patients, with a median age of 63 years and a male to female ratio of 2.3:1. Cytogenetic aberration and genetic mutation were observed in 6 and 3 cases, respectively. The median overall survival (OS) was 48 months and the median leukemia-free survival was 12 months. Post-multivariate analysis, the parameters with significant impact on OS were absolute monocyte count more than 10 × 10^9/L, myeloid precursors in peripheral blood, hemoglobin less than 10g/dL, platelet less than 100 × 10^9/L, hemoglobin less than 12g/dL, and absolute lymphocyte count more than 2.5 × 10^9/L. Conclusion: To summarize, we discovered CPSS to be a better prognostic tool for a setup like ours, since molecular investigations are not always readily available for each case. More such researches are needed in the near future so that we can design better prognostic tools and see for their usefulness in real life.

Epigenetic regulation by ASXL1 in myeloid malignancies.

Myeloid malignancies areclonal hematopoietic disorders that are comprised of a spectrum of genetically heterogeneous disorders, including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML). Myeloid malignancies are characterized by excessive proliferation, abnormal self-renewal, and/or differentiation defects of hematopoietic stem cells (HSCs) and myeloid progenitor cells hematopoietic stem/progenitor cells (HSPCs). Myeloid malignancies can be caused by genetic and epigenetic alterations that provoke key cellular functions, such as self-renewal, proliferation, biased lineage commitment, and differentiation. Advances in next-generation sequencing led to the identification of multiple mutations in myeloid neoplasms, and many new gene mutations were identified as key factors in driving the pathogenesis of myeloid malignancies. The polycomb protein ASXL1 was identified to be frequently mutated in all forms of myeloid malignancies, with mutational frequencies of 20%, 43%, 10%, and 20% in MDS, CMML, MPN, and AML, respectively. Significantly, ASXL1 mutations are associated with a poor prognosis in all forms of myeloid malignancies. The fact that ASXL1 mutations are associated with poor prognosis in patients with CMML, MDS, and AML, points to the possibility that ASXL1 mutation is a key factor in the development of myeloid malignancies. This review summarizes the recent advances in understanding myeloid malignancies with a specific focus on ASXL1 mutations.

Abstract CT085: A phase 2/3, multicenter trial of lenzilumab and azacitidine in chronic myelomonocytic leukemia: The PREACH-M trial

Abstract Background: Chronic myelomonocytic leukemia (CMML) is a rare, aggressive cancer for which no targeted therapy exists. Standard of care (SOC) includes azacitidine (A), with complete and partial response (CR and PR) rates ranging between 10-17%. The pro-inflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a central role in stimulating leukemic monocyte proliferation. Lenzilumab (LENZ) is a proprietary Humaneered® first-in-class monoclonal antibody with best-in-class specificity and affinity that neutralizes GM-CSF to prevent signaling through its receptor. The PREcision Approach to CHronic Myelomonocytic Leukemia (PREACH-M) trial assesses the efficacy of LENZ in CMML (ACTRN12621000223831p) to improve outcomes beyond those afforded by SOC. Methods: PREACH-M is a Phase 2/3 non-randomized, open-label precision medicine trial in 72 adults aged at least 18 years, newly diagnosed with WHO 2016 criteria for CMML; cytopenia (hemoglobin &amp;lt; 100 g/L, platelets &amp;lt; 100 × 109/L or absolute neutrophil count &amp;lt; 1.8 × 109/L): white blood cell count ≥ 13 × 109/L; as well as TET2 and/or RAS pathway mutations (NRAS, KRAS, CBL). Key exclusion criteria include prior treatment with investigational agents; radiotherapy within 28 days before treatment; treatment with G-CSF within 7 days of screening; GM-CSF within 28 days of screening; and uncontrolled medical conditions. Subjects exhibiting RAS pathway mutations, with or without TET2 mutations, receive 24 cycles (28 days) of A (SC; 75 mg/m2 for 7 days) and LENZ (IV; 552 mg; d1 &amp; d15 of cycle 1 and d1 only for all subsequent cycles); while those with non-RAS pathway mutations receive the same A regimen and sodium ascorbate (IV; 30 g for 7 days [15 g for 1st dose only, 30 g thereafter if no evidence of tumor lysis syndrome]; PO; 1.1g on all other days). Subjects who complete 24 cycles of treatment are followed every 6 months for 24 months for survival, disease status, and CMML-related therapy. The primary endpoint is the frequency of CR or PR at any time during the first 12 cycles according to Savona Criteria. Secondary endpoints include overall survival and progression-free survival at 2 years; proportion of subjects with clinical benefit at any point during the 24 cycles; impact on physical and functional capacity; social well-being according to Multidimensional Geriatric Assessment and quality of life; as well as hematological and non-hematologic safety. Results: As of December 31, 2022, eight subjects were treated with A and LENZ (5 females, mean age of 67 years; 3 males, mean age of 69 years); among them 6 were evaluable based on at least 3 months of follow-up. CR or objective responses were observed in all evaluable patients including 2 with high risk based on molecular profiling. 10 grade 3/4 Serious Adverse Events were observed of which 2 were assessed by the investigator as possibly related to LENZ. Conclusion: The ongoing PREACH-M trial evaluates GM-CSF neutralization with LENZ in addition to SOC, in the treatment of CMML with RAS pathway mutations. Citation Format: Devendra Hiwase, David Ross, Steven Lane, Agnes Yong, Kirsty Sharplin, David Yeung, Lisa Butler, Dale Chappell, Cameron Durrant, Timothy Hughes, Daniel Thomas. A phase 2/3, multicenter trial of lenzilumab and azacitidine in chronic myelomonocytic leukemia: The PREACH-M trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT085.

What role for somatic mutations in systemic inflammatory and autoimmune diseases associated with myelodysplastic neoplasms and chronic myelomonocytic leukemias?

What role for somatic mutations in systemic inflammatory and autoimmune diseases associated with myelodysplastic neoplasms and chronic myelomonocytic leukemias?