Trisomy 8 Defines a Distinct Subtype of Myeloproliferative Neoplasms Driven by the MYC-Alarmin Axis

Despite advances in understanding the genetic abnormalities in myeloproliferative neoplasms (MPNs) and the development of JAK2 inhibitors, there is an urgent need to devise new treatment strategies, particularly for triple negative myelofibrosis (MF) patients who lack mutations in the JAK2 kinase pathway and have very poor clinical outcomes. Here we report that MYC copy number gain and increased MYC expression frequently occur in triple negative MF, and that MYC-directed activation of S100A9, an alarmin protein that plays pivotal roles in inflammation and innate immunity, is necessary and sufficient to drive development and progression of MF. Notably, the MYC-S100A9 circuit provokes a complex network of inflammatory signaling that involves numerous hematopoietic cell types in the bone marrow microenvironment. Accordingly, genetic ablation of S100A9 or treatment with small molecules targeting the MYC-S100A9 pathway effectively ameliorates MF phenotypes, highlighting the MYC-alarmin axis as a novel therapeutic vulnerability for this subgroup of MPNs.

Hypomethylating Agents and Venetoclax for Acute Myeloid Leukemia Relapsed After Hematopoietic Stem Cell Transplant

BACKGROUND

Hypomethylating agent + venetoclax is an effective frontline combination for acute myeloid leukemia, but its efficacy and safety in post-allogeneic hematopoietic cell transplant (alloHCT) relapse remain underexplored. Outcomes have been poor for this population, with no standard treatment.

PATIENTS AND METHODS

We retrospectively analyzed 72 Ven-naïve patients who received hypomethylating agents + venetoclax at relapse following alloHCT and aimed to evaluate the rates of complete remission with or without hematologic recovery (CR/CRi) and minimal residual disease (MRD) negativity, CR/CRi duration, and overall survival. We leveraged our larger sample to analyze the impact of cytogenetic/molecular features on the odds of CR/CRi.

RESULTS

CR/CRi was achieved among 32 of 67 (48%) patients, and MRD negativity was recorded among 10 of 12. NPM1 and IDH 1 or 2 mutations increased the odds of CR/CRi, as did increasing time from alloHCT to relapse. Fourteen patients subsequently received donor lymphocyte infusions or a second alloHCT. Responses lasted a median of 17.8 months (95% CI, 7.2 months to not reached), and responders had a greater median overall survival of 19.7 months (95% CI, 7.6-51.5 months) compared to 2.9 months among nonresponders (95% CI, 1.8-4.4 months; log-rank P < .01). Treatment was well tolerated, but prolonged cytopenias were common and most patients required reduction in the number of venetoclax days per cycle.

CONCLUSION

These data support the efficacy of this combination in the alloHCT relapse setting where we report responses among nearly half of patients, with possibly greater benefit for NPM1 and IDH 1/2-mutated cases. These responses can be durable and profound as evidenced by conversion to MRD negativity.

Imetelstat in patients with lower-risk myelodysplastic syndromes who have relapsed or are refractory to erythropoiesis-stimulating agents (IMerge): a multinational, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Unmet medical needs remain in patients with red blood cell transfusion-dependent (RBC-TD) lower-risk myelodysplastic syndromes (LR-MDS) who are not responding to or are ineligible for erythropoiesis-stimulating agents (ESAs). Imetelstat, a competitive telomerase inhibitor, showed promising results in a phase 2 trial. We aimed to compare the RBC transfusion independence (RBC-TI) rate with imetelstat versus placebo in patients with RBC-TD LR-MDS.

METHODS

In phase 3 of IMerge, a double-blind, placebo-controlled trial conducted in 118 sites including university hospitals, cancer centres, and outpatient clinics in 17 countries, patients (aged ≥18 years) with ESA-relapsed, ESA-refractory, or ESA-ineligible LR-MDS (low or intermediate-1 risk disease as per International Prognostic Scoring System [IPSS] criteria) were randomly assigned via a computer-generated schedule (2:1) to receive imetelstat 7·5 mg/kg or placebo, administered as a 2-h intravenous infusion, every 4 weeks until disease progression, unacceptable toxic effects, or withdrawal of consent. Randomisation was stratified by previous RBC transfusion burden and IPSS risk group. Patients, investigators, and those analysing the data were masked to group assignment. The primary endpoint was 8-week RBC-TI, defined as the proportion of patients without RBC transfusions for at least 8 consecutive weeks starting on the day of randomisation until subsequent anti-cancer therapy, if any. Primary efficacy analyses were performed in the intention-to-treat population, and safety analyses were conducted in patients who received at least one dose of trial medication or placebo. This trial is registered with ClinicalTrials.gov (NCT02598661; substudy active and recruiting).

FINDINGS

Between Sept 11, 2019, and Oct 13, 2021, 178 patients were enrolled and randomly assigned (118 to imetelstat and 60 to placebo). 111 (62%) were male and 67 (38%) were female. 91 (77%) of 118 patients had discontinued treatment by data cutoff in the imetelstat group versus 45 (75%) in the placebo group; a further one patient in the placebo group did not receive treatment. Median follow-up was 19·5 months (IQR 12·0-23·4) in the imetelstat group and 17·5 months (12·1-22·7) in the placebo group. In the imetelstat group, 47 (40% [95% CI 30·9-49·3]) patients had an RBC-TI of at least 8 weeks versus nine (15% [7·1-26·6]) in the placebo group (rate difference 25% [9·9 to 36·9]; p=0·0008). Overall, 107 (91%) of 118 patients receiving imetelstat and 28 (47%) of 59 patients receiving placebo had grade 3-4 treatment-emergent adverse events. The most common treatment-emergent grade 3-4 adverse events in patients taking imetelstat were neutropenia (80 [68%] patients who received imetelstat vs two [3%] who received placebo) and thrombocytopenia (73 [62%] vs five [8%]). No treatment-related deaths were reported.

INTERPRETATION

Imetelstat offers a novel mechanism of action with durable transfusion independence (approximately 1 year) and disease-modifying activity for heavily transfused patients with LR-MDS who are not responding to or are ineligible for ESAs.

FUNDING

Janssen Research & Development before April 18, 2019, and Geron Corporation thereafter.

Drivers of deep molecular response and long-term outcomes in patients with core binding factor acute myeloid leukemia

A swimmer plot on clinical course of patients undergoing allogeneic stem cell transplant for core binding factor acute myeloid leukemia.

Standardising acute myeloid leukaemia classification systems: a perspective from a panel of international experts

The existence of two acute myeloid leukaemia classification systems-one put forth by WHO and one by the International Consensus Classification in 2022-is concerning. Although both systems appropriately move towards genomic disease definitions and reduced emphasis on blast enumeration, there are consequential disagreements between the two systems on what constitutes a diagnosis of acute myeloid leukaemia. This fundamental problem threatens the ability of heath-care providers to diagnose acute myeloid leukaemia, communicate with patients and other health-care providers, and deliver appropriate and consistent management strategies for patients with the condition. Clinical trial eligibility, standardised response assessments, and eventual drug development and regulatory pathways might also be negatively affected by the discrepancies. In this Viewpoint, we review the merits and limitations of both classification systems and illustrate how the coexistence, as well as application of both systems is an undue challenge to patients, clinicians, hematopathologists, sponsors of research, and regulators. Lastly, we emphasise the urgency and propose a roadmap, by which the two divergent classification systems can be harmonised.

Telomerase-targeted therapies in myeloid malignancies

Human telomeres are tandem arrays that are predominantly composed of 5'-TTAGGG-3' nucleotide sequences at the terminal ends of chromosomes. These sequences serve 2 primary functions: they preserve genomic integrity by protecting the ends of chromosomes, preventing inappropriate degradation by DNA repair mechanisms, and they prevent loss of genetic information during cellular division. When telomeres shorten to reach a critical length, termed the Hayflick limit, cell senescence or death is triggered. Telomerase is a key enzyme involved in synthesizing and maintaining the length of telomeres within rapidly dividing cells and is upregulated across nearly all malignant cells. Accordingly, targeting telomerase to inhibit uncontrolled cell growth has been an area of great interest for decades. In this review, we summarize telomere and telomerase biology because it relates to both physiologic and malignant cells. We discuss the development of telomere- and telomerase-targeted therapeutic candidates within the realm of myeloid malignancies. We overview all mechanisms of targeting telomerase that are currently in development, with a particular focus on imetelstat, an oligonucleotide with direct telomerase inhibitory properties that has advanced the furthest in clinical development and has demonstrated promising data in multiple myeloid malignancies.

Considerations for Drug Development in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) have historically been challenging diseases for drug development due to their biology, preclinical modeling, and the affected patient population. In April 2022, the FDA convened a panel of regulators and academic experts in MDS to discuss approaches to improve MDS drug development. The panel reviewed challenges in MDS clinical trial design and endpoints and outlined considerations for future trial design in MDS to facilitate drug development to meaningfully meet patient needs. Challenges for defining clinical benefit in patients with MDS include cumbersome response criteria, standardized transfusion thresholds, and application and validation of patient reported outcome instruments. Clinical trials should reflect the biology of disease evolution, the advanced age of patients with MDS, and how patients are treated in real-world settings to maximize the likelihood of identifying active drugs. In patients with lower-risk disease, response criteria for anemic patients should be based on baseline transfusion dependency, improvement in symptoms, and quality of life. For higher-risk patients with MDS, trials should include guidance to prevent dose reductions or delays that could limit efficacy, specify minimal durations of treatment (in the absence of toxicity or progression), and have endpoints focused on overall survival and durable responses. MDS trials should be designed from the outset to allow the practicable application of new therapies in this high-needs population, with drugs that can be administered and tolerated in community settings, and with endpoints that meaningfully improve patients' lives over existing therapies.

Efficacy and safety of luspatercept versus epoetin alfa in erythropoiesis-stimulating agent-naive, transfusion-dependent, lower-risk myelodysplastic syndromes (COMMANDS): interim analysis of a phase 3, open-label, randomised controlled trial

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) are the standard-of-care treatment for anaemia in most patients with lower-risk myelodysplastic syndromes but responses are limited and transient. Luspatercept promotes late-stage erythroid maturation and has shown durable clinical efficacy in patients with lower-risk myelodysplastic syndromes. In this study, we report the results of a prespecified interim analysis of luspatercept versus epoetin alfa for the treatment of anaemia due to lower-risk myelodysplastic syndromes in the phase 3 COMMANDS trial.

METHODS

The phase 3, open-label, randomised controlled COMMANDS trial is being conducted at 142 sites in 26 countries. Eligible patients were aged 18 years or older, had a diagnosis of myelodysplastic syndromes of very low risk, low risk, or intermediate risk (per the Revised International Prognostic Scoring System), were ESA-naive, and required red blood cell transfusions (2-6 packed red blood cell units per 8 weeks for ≥8 weeks immediately before randomisation). Integrated response technology was used to randomly assign patients (1:1, block size 4) to luspatercept or epoetin alfa, stratified by baseline red blood cell transfusion burden (<4 units per 8 weeks vs ≥4 units per 8 weeks), endogenous serum erythropoietin concentration (≤200 U/L vs >200 to <500 U/L), and ring sideroblast status (positive vs negative). Luspatercept was administered subcutaneously once every 3 weeks starting at 1·0 mg/kg body weight with possible titration up to 1·75 mg/kg. Epoetin alfa was administered subcutaneously once a week starting at 450 IU/kg body weight with possible titration up to 1050 IU/kg (maximum permitted total dose of 80 000 IU). The primary endpoint was red blood cell transfusion independence for at least 12 weeks with a concurrent mean haemoglobin increase of at least 1·5 g/dL (weeks 1-24), assessed in the intention-to-treat population. Safety was assessed in patients who received at least one dose of study treatment. The COMMANDS trial was registered with ClinicalTrials.gov, NCT03682536 (active, not recruiting).

FINDINGS

Between Jan 2, 2019 and Aug 31, 2022, 356 patients were randomly assigned to receive luspatercept (178 patients) or epoetin alfa (178 patients), comprising 198 (56%) men and 158 (44%) women (median age 74 years [IQR 69-80]). The interim efficacy analysis was done for 301 patients (147 in the luspatercept group and 154 in the epoetin alfa group) who completed 24 weeks of treatment or discontinued earlier. 86 (59%) of 147 patients in the luspatercept group and 48 (31%) of 154 patients in the epoetin alfa group reached the primary endpoint (common risk difference on response rate 26·6; 95% CI 15·8-37·4; p<0·0001). Median treatment exposure was longer for patients receiving luspatercept (42 weeks [IQR 20-73]) versus epoetin alfa (27 weeks [19-55]). The most frequently reported grade 3 or 4 treatment-emergent adverse events with luspatercept (≥3% patients) were hypertension, anaemia, dyspnoea, neutropenia, thrombocytopenia, pneumonia, COVID-19, myelodysplastic syndromes, and syncope; and with epoetin alfa were anaemia, pneumonia, neutropenia, hypertension, iron overload, COVID-19 pneumonia, and myelodysplastic syndromes. The most common suspected treatment-related adverse events in the luspatercept group (≥3% patients, with the most common event occurring in 5% patients) were fatigue, asthenia, nausea, dyspnoea, hypertension, and headache; and none (≥3% patients) in the epoetin alfa group. One death after diagnosis of acute myeloid leukaemia was considered to be related to luspatercept treatment (44 days on treatment).

INTERPRETATION

In this interim analysis, luspatercept improved the rate at which red blood cell transfusion independence and increased haemoglobin were achieved compared with epoetin alfa in ESA-naive patients with lower-risk myelodysplastic syndromes. Long-term follow-up and additional data will be needed to confirm these results and further refine findings in other subgroups of patients with lower-risk myelodysplastic syndromes, including non-mutated SF3B1 or ring sideroblast-negative subgroups.

FUNDING

Celgene and Acceleron Pharma.

Assessment and validation of the molecular international prognostic scoring system for myelodysplastic syndromes

The Molecular International Prognostic Scoring System (IPSS-M) is a novel risk stratification model for myelodysplastic syndromes (MDS) that builds on the IPSS and IPSS-R by incorporating mutational data. The model showed improved prognostic accuracy over the IPSS-R across three endpoints: overall survival (OS), leukemia-free survival (LFS) and leukemic transformation. This study aimed to validate the findings of the original in a large cohort of MDS patients, as well as assess its validity in therapy-related and hypoplastic MDS. We retrospectively reviewed clinical, cytogenetic and molecular data for 2355 MDS patients treated at the Moffitt Cancer Center. Correlative analysis between IPSS-R and mean IPSS-M scores and outcome predictions was performed on LFS, OS and leukemic transformation. Using the IPSS-M, patients were classified as Very Low (4%), Low (24%), Moderate-Low (14%), Moderate-High (11%), High (19%) and Very-High risk (28%). Median OS was 11.7, 7.1, 4.4, 3.1, 2.3, and 1.3 years from VL to VH risk subgroups. Median LFS was 12.3, 6.9, 3.6, 2.2, 1.4, and 0.5 years respectively. For patients with t-MDS and h-MDS the model retained its prognostic accuracy. Generalized use of this tool will likely result in more accurate prognostic assessment and optimize therapeutic decision-making in MDS.

Sex Disparities in Myelodysplastic Syndromes: Genotype, Phenotype, and Outcomes

Introduction/Background The impact of biological sex on the clinical phenotype, genotype, and outcomes among patients with MDS is not well characterized. Materials and Methods We retrospectively reviewed the clinical and genomic data from male and female patients included in our institutional MDS database at Moffitt Cancer Center. Results Among 4580 patients with MDS, 2922 (66%) were men and 1658 (34%) were women. Women were younger (mean age 66.5 vs. 69 years for men, P < .001) at diagnosis. There were more Hispanic/black women than men (9% vs. 5%, P =<.001). Women had lower hemoglobin and higher platelet counts than men. More women had del 5q/monosomy 5 abnormalities compared to men (P =<.001). Therapy related MDS were more common in women than men (25% vs.17%, P=<.001). On assessment of molecular profile, SRSF2, U2AF1, ASXL1, and RUNX1 mutations were more frequent in men. The median overall survival (mOS) was 37.5 months (mo) for females compared to 35 monthsfor males, (P = .002). The mOS was significantly prolonged for women in lower-risk MDS, but not in higher-risk MDS. Women were more likely to respond to immunosuppression with ATG/CSA than men (38% vs. 19%, P= 0.04).Conclusion Ongoing research is needed for understanding the impact of sex on phenotype, genotype, and outcomes in patients diagnosed with MDS.

Updates in Risk Stratification in Myelodysplastic Syndromes

ABSTRACT

Risk stratification plays an essential role in treatment planning in myelodysplastic syndromes. For decades, the International Prognostic Scoring System and its revised version have provided unified consensus for clinical trial enrollment and design. These models relied on laboratory and cytogenetic data to estimate prognosis and dictate treatment paradigms. Critical developments in DNA sequencing techniques in recent years, as well as our growing understanding of the clonal dynamics of myelodysplastic syndromes and the role that specific mutations have in shaping disease-specific phenotypes and treatment susceptibilities, have made it possible to identify molecular markers that carry critical diagnostic and therapeutic relevance and remained unaccounted for in the older models. The Molecular International Prognostic Scoring System is a novel risk stratification model that integrates clinical, cytogenetic, and molecular data to devise a more refined prognostic tool that builds on the accuracy of the traditional models.

Transplant Referral Patterns for Patients with Newly Diagnosed Higher-Risk Myelodysplastic Syndromes and Acute Myeloid Leukemia at Academic and Community Sites in the Connect® Myeloid Disease Registry: Potential Barriers to Care

BACKGROUND

Hematopoietic stem cell transplantation (HCT) is indicated for patients with higher-risk (HR) myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Age, performance status, patient frailty, comorbidities, and non-clinical factors (eg, cost, distance to site) are all recognized as important clinical factors that can influence HCT referral patterns and patient outcomes. However, the proportion of eligible patients referred for HCT in routine clinical practice is largely unknown.

OBJECTIVE

This study aimed to assess patterns of consideration for HCT among patients with HR-MDS and AML enrolled in the Connect® Myeloid Disease Registry, at community/government (CO/GOV)- or academic (AC)-based sites, as well as to identify factors associated with transplant referral rates.

STUDY DESIGN

We assessed patterns of consideration for, and completion of, HCT among patients with HR-MDS and AML enrolled between December 12, 2013 and March 6, 2020 in the Connect® Myeloid Disease Registry at 164 CO/GOV and AC sites. Registry sites recorded whether patients were considered for transplant at baseline and at each follow-up visit. The following answers were possible: "considered potentially eligible", "not considered potentially eligible", or "not assessed". Sites also recorded whether patients subsequently underwent HCT at each follow-up visit. Comparison of transplant consideration rates between CO/GOV and AC sites was performed using multivariable logistic regression analysis with covariates for age and comorbidity.

RESULTS

Among the 778 patients with HR-MDS or AML enrolled in the Registry, patients at CO/GOV sites (27.9%) were less likely to be considered potentially eligible for HCT than patients at AC sites (43.9%; (P < .0001). Multivariable logistic regression analysis with factors for age (<65 versus ≥65 years) and ACE-27 comorbidity grade (<2 versus ≥2) demonstrated that patients at CO/GOV sites were significantly less likely to be considered potentially eligible for transplant than those at AC sites (odds ratio: 1.6, 95% confidence interval [CI], 1.1-2.4, P = .0155). Of patients considered eligible for transplant, 45.1% (65/144) and 35.7% (41/115) of patients at CO/GOV and AC sites, respectively, underwent transplantation (P = .12). Approximately half of all patients at CO/GOV (50.1%) and AC (45.4%) sites were not considered potentially eligible for HCT; the most common reasons were age at CO/GOV sites (71.5%) and comorbidities at AC sites (52.1%). Across all sites, 17.4% of patients across all sites were reported as not assessed (and thus not considered) for transplant by their treating physician (20.7% at CO/GOV and 10.7% at AC sites; P = .0005).

CONCLUSIONS

These findings suggest many patients with HR-MDS and AML who may be candidates for HCT are not receiving assessment or consideration for transplant in clinical practice. In addition, treatment at CO/GOV sites and age are still significant barriers to ensuring all potentially eligible patients are assessed for HCT.

SOHO State of the Art Updates and Next Questions: Treatment of Lower Risk Myelodysplastic Syndromes

MDS is a clonal stem cell neoplasm with a spectrum from lower risk disease to short term life threatening higher risk disease. The disease risk is dictated by clinical and molecular features. Majority of MDS patients including lower risk disease unfortunately succumb from disease related complications namely cytopenia. While cytopenias may be mild early upon diagnosis and can be surveilled, ultimately treatment is required. Anemia is the hall mark of disease and most common indication to treat in lower risk MDS. Erythroid stimulating agents are used in the first line setting. Treatment can be a personalized approach as in select patient such as patients with del(5q) and those with ringed sideroblasts, lenalidomide, and luspatercept can be extremely effective respectively at improving cytopenias. Younger patients and hypoplastic MDS have also shown and improved response to immunosuppressive therapy. Hypomethylating agents can be option for patients with higher risk features or thrombocytopenia/neutropenia. Refractory cytopenias still poses frustration as options are limited and there is need to add more treatments to our armamentarium.

Improved benefit of continuing luspatercept therapy: sub-analysis of patients with lower-risk MDS in the MEDALIST study

Red blood cell transfusion independence (RBC-TI) is an important goal in treating lower-risk myelodysplastic syndromes with ring sideroblasts. In the phase 3 MEDALIST study, RBC-TI of ≥ 8 weeks was achieved by significantly more luspatercept- versus placebo-treated patients in the first 24 weeks of treatment. In this post hoc analysis, we evaluated RBC transfusion units and visits based on patients' baseline transfusion burden level and the clinical benefit of luspatercept treatment beyond week 25 in initial luspatercept nonresponders (patients who did not achieve RBC-TI ≥ 8 weeks by week 25) but continued luspatercept up to 144 weeks. RBC transfusion burden, erythroid response, serum ferritin levels, and hemoglobin levels relative to baseline were evaluated. Through week 25, fewer RBC transfusion units and visits were observed in luspatercept-treated patients versus placebo, regardless of baseline transfusion burden. This continued through 144 weeks of luspatercept treatment, particularly in patients with low baseline transfusion burden. Sixty-eight patients were initial nonresponders at week 25 but continued treatment; most (81%) received the maximum dose of luspatercept (1.75 mg/kg). Sixteen percent achieved RBC-TI for ≥ 8 weeks during weeks 25-48, 26% had reduced RBC transfusion burden, 10% achieved an erythroid response, 44% had reduced serum ferritin, and hemoglobin levels increased an average of 1.3 g/dL from baseline. These data have implications for clinical practice, as transfusion units and visits are less in luspatercept-treated patients through week 25 regardless of baseline transfusion burden, and continuing luspatercept beyond week 25 can potentially provide additional clinical benefits for initial nonresponders. Trial registration: NCT02631070.

Progenitor Hierarchy of Chronic Myelomonocytic Leukemia Identifies Inflammatory Monocytic-Biased Trajectory Linked to Worse Outcomes

Myeloblast expansion is a hallmark of disease progression and comprises CD34+ hematopoietic stem and progenitor cells (HSPC). How this compartment evolves during disease progression in chronic myeloid neoplasms is unknown. Using single-cell RNA sequencing and high-parameter flow cytometry, we show that chronic myelomonocytic leukemia (CMML) CD34+ HSPC can be classified into three differentiation trajectories: monocytic, megakaryocyte-erythroid progenitor (MEP), and normal-like. Hallmarks of monocytic-biased trajectory were enrichment of CD120b+ inflammatory granulocyte-macrophage progenitor (GMP)-like cells, activated cytokine receptor signaling, phenotypic hematopoietic stem cell (HSC) depletion, and adverse outcomes. Cytokine receptor diversity was generally an adverse feature and elevated in CD120b+ GMPs. Hypomethylating agents decreased monocytic-biased cells in CMML patients. Given the enrichment of RAS pathway mutations in monocytic-biased cells, NRAS-competitive transplants and LPS-treated xenograft models recapitulated monocytic-biased CMML, suggesting that hematopoietic stress precipitates the monocytic-biased state. Deconvolution of HSPC compartments in other myeloid neoplasms and identifying therapeutic strategies to mitigate the monocytic-biased differentiation trajectory should be explored.

SIGNIFICANCE

Our findings establish that multiple differentiation states underlie CMML disease progression. These states are negatively augmented by inflammation and positively affected by hypomethylating agents. Furthermore, we identify HSC depletion and expansion of GMP-like cells with increased cytokine receptor diversity as a feature of myeloblast expansion in inflammatory chronic myeloid neoplasms. This article is highlighted in the In This Issue feature, p. 476.

The ABNL-MARRO 001 study: a phase 1–2 study of randomly allocated active myeloid target compound combinations in MDS/MPN overlap syndromes

Background

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) comprise several rare hematologic malignancies with shared concomitant dysplastic and proliferative clinicopathologic features of bone marrow failure and propensity of acute leukemic transformation, and have significant impact on patient quality of life. The only approved disease-modifying therapies for any of the MDS/MPN are DNA methyltransferase inhibitors (DNMTi) for patients with dysplastic CMML, and still, outcomes are generally poor, making this an important area of unmet clinical need. Due to both the rarity and the heterogeneous nature of MDS/MPN, they have been challenging to study in dedicated prospective studies. Thus, refining first-line treatment strategies has been difficult, and optimal salvage treatments following DNMTi failure have also not been rigorously studied. ABNL-MARRO (A Basket study of Novel therapy for untreated MDS/MPN and Relapsed/Refractory Overlap Syndromes) is an international cooperation that leverages the expertise of the MDS/MPN International Working Group (IWG) and provides the framework for collaborative studies to advance treatment of MDS/MPN and to explore clinical and pathologic markers of disease severity, prognosis, and treatment response.

Methods

ABNL MARRO 001 (AM-001) is an open label, randomly allocated phase 1/2 study that will test novel treatment combinations in MDS/MPNs, beginning with the novel targeted agent itacitinib, a selective JAK1 inhibitor, combined with ASTX727, a fixed dose oral combination of the DNMTi decitabine and the cytidine deaminase inhibitor cedazuridine to improve decitabine bioavailability.

Discussion

Beyond the primary objectives of the study to evaluate the safety and efficacy of novel treatment combinations in MDS/MPN, the study will (i) Establish the ABNL MARRO infrastructure for future prospective studies, (ii) Forge innovative scientific research that will improve our understanding of pathogenetic mechanisms of disease, and (iii) Inform the clinical application of diagnostic criteria, risk stratification and prognostication tools, as well as response assessments in this heterogeneous patient population.

Trial registration

This trial was registered with ClinicalTrials.gov on August 19, 2019 (Registration No. NCT04061421).

Role of allogeneic transplantation in chronic myelomonocytic leukemia: an international collaborative analysis

To determine the survival benefit of allogeneic hematopoietic cell transplantation (allo-HCT) in chronic myelomonocytic leukemias (CMML), we assembled a retrospective cohort of CMML patients 18-70 years old diagnosed between 2000 and 2014 from an international CMML dataset (n = 730) and the EBMT registry (n = 384). The prognostic impact of allo-HCT was analyzed through univariable and multivariable time-dependent models and with a multistate model, accounting for age, sex, CMML prognostic scoring system (low or intermediate-1 grouped as lower-risk, intermediate-2 or high as higher-risk) at diagnosis, and AML transformation. In univariable analysis, lower-risk CMMLs had a 5-year overall survival (OS) of 20% with allo-HCT vs 42% without allo-HCT (P < .001). In higher-risk patients, 5-year OS was 27% with allo-HCT vs 15% without allo-HCT (P = .13). With multistate models, performing allo-HCT before AML transformation reduced OS in patients with lower-risk CMML, and a survival benefit was predicted for men with higher-risk CMML. In a multivariable analysis of lower-risk patients, performing allo-HCT before transformation to AML significantly increased the risk of death within 2 years of transplantation (hazard ratio [HR], 3.19; P < .001), with no significant change in long-term survival beyond this time point (HR, 0.98; P = .92). In higher-risk patients, allo-HCT significantly increased the risk of death in the first 2 years after transplant (HR 1.46; P = .01) but not beyond (HR, 0.60; P = .09). Performing allo-HCT before AML transformation decreases life expectancy in lower-risk patients but may be considered in higher-risk patients.

Disease-related thrombocytopenia in myelofibrosis is defined by distinct genetic etiologies and is associated with unique prognostic correlates

BACKGROUND

Thrombocytopenia in patients with myelofibrosis (MF) is prognostically detrimental and poses a therapeutic challenge. MF patients with thrombocytopenia are considered high-risk by most prognostic models and their distinct phenotype has given rise to the emerging concept of cytopenic MF. Yet, the mechanisms underlying thrombocytopenia in MF are poorly understood.

METHODS

This study aimed to highlight the genetic mechanisms driving low platelet counts in treatment-naive MF patients, establish their phenotypic correlates, and assess prognostic factors specific to this group of patients.

RESULTS

The authors found that most patients presenting with low platelets had a clear thrombocytopenia-specific genetic abnormality involving a U2AF1 Q157 mutation, deletion 20q, molecular complexity (three or more mutations), or high-risk karyotype. Etiologic clustering did not correlate with prognosis; however, thrombocytopenic patients were found to have unique prognostic variables including low serum albumin and mutations of SRSF2 and TP53. This led to the proposal of a prognostic model (SRSF2, albumin, TP53 score) that stratifies thrombocytopenic patients as low, intermediate, or high-risk with corresponding median survivals of 93.5, 29.5, and 7.2 months, respectively.

CONCLUSIONS

This study demonstrates that thrombocytopenia in MF is driven by different genetic mechanisms and is not uniformly high-risk. As novel agents with improved hematologic safety profiles enter the treatment landscape, thoughtful, risk-adapted therapeutic decisions will be required for MF patients with thrombocytopenia.

LAY SUMMARY

A significant minority of patients with myelofibrosis (MF) present with low platelets. Historically, these patients have been viewed as having "high-risk" disease, but this may not be uniformly true. Our study shows that there are various different causes for low platelets in MF, some of which represent high-risk disease whereas others do not. Additionally, our study shows that genetic mutations affecting the genes SRSF2 and TP53 are uniquely problematic in this group, as is a low serum albumin level. This study helps to risk-stratify MF patients with thrombocytopenia, thereby providing more information to guide informed and individualized treatment decisions.

Splicing factor 3B subunit 1 (SF3B1) mutation in the context of therapy-related myelodysplastic syndromes

Splicing factor 3B subunit 1 (SF3B1) somatic mutation in the context of therapy-related myelodysplastic syndromes (t-MDS) has not been well defined. In a large cohort of patients with MDS, those with known SF3B1 somatic mutation were compared as de novo MDS (n = 289) and t-MDS with mutant SF3B1 (SF3B1^mut ; n = 31). Baseline characteristics, concomitant mutations, and acute myeloid leukaemia (AML) transformation were similar between the two groups. The median overall survival (OS) of de novo MDS SF3B1^mut was significantly longer compared to t-MDS SF3B1^mut but not significantly different when adjusted for comorbidities. Comparing t-MDS wild-type SF3B1 (SF3B1^WT ; n = 241) to t-MDS SF3B1^mut (n = 31), complex cytogenetics were seen in 37.4% versus 10.3% (p = 0.009), tumour protein p53 (TP53) mutation was 36.1% versus 10% (p = 0.004), and AML transformation was 34.4% compared to 12.9% (p = 0.016) respectively. OS was significantly shorter in SF3B1^WT versus SF3B1^mut . When applying the International Working Group for Prognosis of MDS (IWG-PM) proposed SF3B1 criteria, OS was significantly shorter in SF3B1^mut t-MDS compared to de novo MDS SF3B1^mut with no significance in AML transformation. Survival was compared between t-MDS SF3B1^mut who met the new proposed IWG-PM criteria to t-MDS SF3B1^mut who did not meet criteria to survival of SF3B1^WT t-MDS. OS was 53 versus 22 and 18 months respectively (p = 0.006). AML transformation was 0%, 26.7% and 32.3% (p = 0.021). Leukaemia-free survival was not reached among the three.

Long-term utilization and benefit of luspatercept in patients (pts) with lower-risk myelodysplastic syndromes (LR-MDS) from the MEDALIST trial

7056

Background: Luspatercept was previously shown to improve anemia in the phase 3 MEDALIST trial of pts with LR-MDS ineligible, intolerant, or refractory to erythropoiesis-stimulating agents (ESAs). Here, we report the long-term clinical value of luspatercept treatment (Tx) in pts from the MEDALIST study including dosing and rates of progression to acute myeloid leukemia (AML) and high-risk MDS (HR-MDS). Methods: Eligible pts were ≥ 18 y of age, had LR-MDS requiring regular red blood cell (RBC) transfusions, and were ineligible/intolerant or refractory to ESAs. Pts were randomized 2:1 to subcutaneous luspatercept or placebo every 3 wk for 24 wk. The primary endpoint was RBC transfusion independence (RBC-TI) ≥ 8 wk during wk 1–24. MEDALIST pts were eligible for enrollment into the long-term follow-up study. Median duration of Tx and cumulative duration of response were determined by Kaplan–Meier (KM) analysis. Total person-years for pts at risk of HR-MDS/AML progression was calculated from LR-MDS diagnosis to HR-MDS/AML diagnosis, or to last HR-MDS/AML follow-up date for pts who did not progress. Results: As of January 15, 2021, the median duration of Tx was 11.70 (95% CI, 8.97–16.33) mo for luspatercept pts and 5.52 (95% CI, 5.52–5.59) mo for placebo pts. Of those enrolled in MEDALIST, 106/153 (69.3%) pts receiving luspatercept and 64/76 (84.2%) receiving placebo escalated to the maximum dose of 1.75 mg/kg. During the entire Tx phase, RBC-TI ≥ 8 wk was observed in 74/153 (48.4%) and 12/76 (15.8%) pts in the luspatercept and placebo arms, respectively, with a median cumulative duration of response of 80.7 (95% CI, 53.71–154.14) wk and 21.0 (95% CI, 10.86–NE) wk, respectively. During the entire Tx period, RBC-TI ≥ 16 wk was observed in 48/153 (31.4%) and 6/76 (7.9%) pts in the luspatercept and placebo arms, respectively (Table). Among pts randomized to luspatercept, 13/153 (8.5%) progressed to HR-MDS/AML during the entire Tx period, compared with 5/76 (6.6%) for placebo. The total person-years for pts randomized to luspatercept at risk of progressing to HR-MDS/AML was 401.7 y vs 190.9 y for placebo. Conclusions: Pts receiving luspatercept had an extended period of clinical benefit and > 50% of pts continued to receive luspatercept for > 1 y, the majority of whom underwent dose escalations to achieve an optimal response. Pts experienced durable responses with luspatercept, with a median cumulative duration of RBC-TI response of approximately 20 mo. Pts receiving luspatercept also appeared to have a longer time to HR-MDS/AML progression than those receiving placebo.[Table: see text]

Hyperferritinemia as predictive biomarker of poor clinical outcomes in CMML

7055

Background: CMML is a heterogenous disease exhibiting features innate to MPN and MDS. Increasing evidence supports a close interplay between systemic inflammation and risk of myeloid malignancies, notably for those with history of infection or autoimmune disease. CMML has been associated with inflammation and end-organ damage related to CKD and CVD. Analysis of gene signatures from CMML-derived monocytes has shown them to be highly proinflammatory. High ferritin may serve as a practical biomarker of disease activity to help identify pts at higher risk of poor outcomes. Methods: Retrospective data was collected from a database of CMML pts treated at Moffitt Cancer Center. Pts were stratified in 2 cohorts based on ferritin levels ( < 1000 or ≥1000 ng/mL). Hyperferritinemia was defined as ferritin > 1000 as seen at diagnosis or during follow-up. Kaplan–Meier was used to estimate OS. Cox regression was used for multivariate analysis. Results: Between August 1995 and October 2020 729 pts with CMML were identified. Median age at diagnosis was 71 (17-95). Out of 571 pts with available ferritin levels 29% (n = 168) developed hyperferritinemia vs 71% (n = 403) who did not. mOS was 32.4 mos (95%CI 30-35 mos). Pts with higher ferritin tended to present with CMML-2 (p = 0.001) and harbor a proliferative phenotype (p = 0.01). They presented with higher marrow cellularity (mean 83%, p = 0.08), PLT (mean 177k, p = 0.038), and lower Hb (mean 9.5, p < 0.05). There was no association with % circulating IMC, monocytes, WBC or ANC at baseline. Hyperferritinemia was associated with more profound fibrosis (p = 0.007), cytopenias (p < 0.05), % peripheral blasts (p < 0.05), RBC and PLT transfusion dependence (p < 0.05). Pts with hyperferritinemia had higher risk disease per IPSS-R, CPSS and all CMML models (p < 0.05); and had higher rates of AML transformation (p < 0.05). Pts were also more likely to require treatment earlier (within 3 yrs of diagnosis) (p < 0.05). ASXL1 (p = 0.002), EZH2 (p = 0.003), and SETBP1 (p = 0.019) mutations were more common among pts with hyperferritinemia. Conversely, TET2 (p = 0.001), CBL (p = 0.028) and SRSF2 (p = 0.003) mutations were less common. mOS for pts with hyperferritinemia was 23.9 mos (95%CI 19.9-27.9 mos), much lower than for those with ferritin < 1000 (mOS 40.5 mos, 95%CI 35.4-45.5 mos) (p < 0.05). In multivariate analysis, hyperferritinemia was a significant independent covariate for OS after adjusting for CPSS, transfusion dependence and disease phenotype (dysplastic vs proliferative) (HR = 0.69; 95%CI 0.53-0.89; p = 0.005). Conclusions: Almost 1/3 of pts with CMML will develop hyperferritinemia. This is associated with more aggressive disease and higher rates of AML transformation leading to dismal outcomes. ASXL1, EZH2, and SETBP1 MTs confer a higher risk of hyperferritinemia. Our findings indicate that hyperferritinemia is an independent prognostic biomarker that may serve as a surrogate representative of disease biology and comorbidities in CMML.

Addition of Navitoclax to Ongoing Ruxolitinib Therapy for Patients With Myelofibrosis With Progression or Suboptimal Response: Phase II Safety and Efficacy

PURPOSE

Targeting the BCL-XL pathway has demonstrated the ability to overcome Janus kinase inhibitor resistance in preclinical models. This phase II trial investigated the efficacy and safety of adding BCL-XL/BCL-2 inhibitor navitoclax to ruxolitinib therapy in patients with myelofibrosis with progression or suboptimal response to ruxolitinib monotherapy (ClinicalTrials.gov identifier: NCT03222609).

METHODS

Thirty-four adult patients with intermediate-/high-risk myelofibrosis who had progression or suboptimal response on stable ruxolitinib dose (≥ 10 mg twice daily) were administered navitoclax at 50 mg once daily starting dose, followed by escalation to a maximum of 300 mg once daily in once in weekly increments (if platelets were ≥ 75 × 109/L). The primary end point was ≥ 35% spleen volume reduction (SVR35) from baseline at week 24. Secondary end points included ≥ 50% reduction in total symptom score (TSS50) from baseline at week 24, hemoglobin improvement, change in bone marrow fibrosis (BMF) grade, and safety.

RESULTS

High molecular risk mutations were identified in 58% of patients, and 52% harbored ≥ 3 mutations. SVR35 was achieved by 26.5% of patients at week 24, and by 41%, at any time on study, with an estimated median duration of SVR35 of 13.8 months. TSS50 was achieved by 30% (6 of 20) of patients at week 24, and BMF improved by 1-2 grades in 33% (11 of 33) of evaluable patients. Anemia response was achieved by 64% (7 of 11), including one patient with baseline transfusion dependence. Median overall survival was not reached with a median follow-up of 21.6 months. The most common adverse event was reversible thrombocytopenia without clinically significant bleeding (88%).

CONCLUSION

The addition of navitoclax to ruxolitinib in patients with persistent or progressive myelofibrosis resulted in durable SVR35, improved TSS, hemoglobin response, and BMF. Further investigation is underway to qualify the potential for disease modification.

Imetelstat in intermediate-2 or high-risk myelofibrosis refractory to JAK inhibitor: IMpactMF phase III study design

Imetelstat, a first-in-class telomerase inhibitor, demonstrated meaningful clinical benefit including a robust symptom response rate and potential overall survival benefit in IMbark, a phase II study in intermediate-2 or high-risk MF patients who have relapsed after or are refractory to JAK inhibitors. We describe the rationale and design for the phase III trial, IMpactMF (NCT04576156), an open-label evaluation of imetelstat versus best available therapy, excluding JAK inhibitors, in MF patients refractory to JAK inhibitor. Imetelstat 9.4 mg/kg is administered as an intravenous infusion every 21 days. Primary objective is to assess overall survival. Secondary objectives include symptom and spleen responses, progression-free survival, clinical response assessment, bone marrow fibrosis reduction, safety and pharmacokinetics. Biomarker, cytogenetics and mutation analyses will be performed.

Prognostic scoring systems and risk stratification in myelodysplastic syndrome: focus on integration of molecular profile

Myelodysplastic syndromes (MDS) form a clinically and molecularly heterogeneous disease group. Precise risk stratification remains crucial for choosing optimal management strategies. Several conventional prognostic scoring systems have been developed and validated in the MDS population. These risk models divide patients into prognostic subgroups based on clinical and cytogenetic characteristics. Lack of dynamicity, variable risk estimate across models, and heterogeneity within intermediate-risk group are the limitations of traditional models like IPSS-R, with questionable relevance of these scoring systems in treated MDS patients. Recent progress in next-generation sequencing techniques has improved understanding of the distribution and prognostic importance of recurrent genetic mutations in MDS. Early studies have suggested that incorporating mutations in risk stratification could supplement IPSS-R in further refining the model's performance in predicting overall survival and risk of transformation to acute myeloid leukemia and should translate into a molecularly driven prognostication approach in the near future.

MYC overexpression is associated with an early disease progression from MDS to AML

Recent studies demonstrated that MYC epigenetically regulates AML cell survival and differentiation by suppressing IDH1/2-TET2-5hmC signaling and that MYC overexpression is associated with poor survival outcomes in multiple AML patient cohorts. However, the oncogenic roles of MYC in MDS remain to be explored. A total of 41 patients with de novo MDS were retrospectively identified using the Total Cancer Care database at the Moffitt Cancer Center. A total of 61 % of patients had low MYC expression and 39 % of patients had high MYC expression defined as MYC reactivity by immunohistochemical staining in ≥5% of bone marrow (BM) cells at the time of MDS diagnosis. The median MDS-to-AML progression free survival (PFS) was significantly shorter in the high MYC group (median PFS 9.3 vs. 17.7 months, HR = 2.328, p = 0.013). Further, overall survival (OS) was also shorter in the high MYC patients (median OS 19.7 vs. 51.7 months, HR = 2.299, p = 0.053). Multivariate analyses demonstrated that high MYC expression is an independent poor prognostic factor for the MDS-to-AML progression (HR = 2.275, p = 0.046). Our observations indicate that MYC may play a crucial role in MDS transformation to AML and the underlying mechanisms of MYC-driven MDS clonal expansion and leukemic transformation require further investigation.

Myelodysplastic Syndromes: A New Decade

Myelodysplastic syndromes (MDS) are a group of heterogeneous clonal hematopoietic stem cell disorders. The 2020 Surveillance, Epidemiology, and End Results data demonstrates the incidence rate of MDS increases with age especially in those greater than 70 years of age. Risk stratification that impact prognosis, survival, and rate of acute myeloid leukemia (AML) transformation in MDS is largely dependent on revised International Prognostic Scoring System along with molecular genetic testing as a supplement. Low risk MDS typically have a more indolent disease course in which treatment is only initiated to ameliorate symptoms of cytopenias. In many, anemia is the most common cytopenia requiring treatment and erythroid stimulating agents, are considered first line. In contrast, high risk MDS tend to behave more aggressively for which treatment should be initiated rapidly with Hypomethylating Agents (HMA) being in the frontline. In those with high risk MDS and eligible, evaluation for allogeneic stem cell transplant should be considered as this is the only potential curative option for MDS. With the use of molecular genetic testing, a personalized approach to therapy in MDS has ensued. As the treatment landscape in MDS continues to flourish with novel targeted agents, we ambitiously seek to improve survival rates especially among the relapsed/refractory and transplant ineligible.

JAK Be Nimble: Reviewing the Development of JAK Inhibitors and JAK Inhibitor Combinations for Special Populations of Patients with Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm hallmarked by uncontrolled blood counts, constitutional symptoms, extramedullary hematopoiesis, and an increased risk of developing acute myeloid leukemia. Janus kinase (JAK) inhibitors are the most common treatment for MF due to their ability to reduce spleen size and improve disease-related symptoms; however, JAK inhibitors are not suitable for every patient and their impact on MF is limited in several respects. Novel JAK inhibitors and JAK inhibitor combinations are emerging that aim to enhance the treatment landscape, providing deeper responses to a broader population of patients with the continued hope of providing disease modification and improving long-term outcomes. In this review, we highlight several specific areas of unmet need within MF. Subsequently, we review agents that target those areas of unmet need, focusing specifically on the JAK inhibitors, momelotinib, pacritinib, itacitinib, and NS-018 as well as JAK inhibitor combination approaches using CPI-0610, navitoclax, parsaclisib, and luspatercept.

Integrated Human and Murine Clinical Study Establishes Clinical Efficacy of Ruxolitinib in Chronic Myelomonocytic Leukemia

PURPOSE

CMML is a rare leukemia characterized by peripheral monocytosis with no disease-modifying therapies. CMML cells are uniquely hypersensitive to GM-CSF and robustly engraft in immunocompromised mice that secrete human cytokines. To leverage these unique biologic features, we conducted an integrated human and murine study evaluating ruxolitinib, a JAK1/2 inhibitor that potently downregulates intracellular GM-CSF signaling.

PATIENTS AND METHODS

A total of 50 patients with WHO-defined CMML were enrolled in this open-label, multi-institution phase 1/2 clinical study, with a ruxolitinib dose of 20mg twice daily studied in phase 2. In parallel, 49 patient-derived xenografts (PDX) derived from 13 study participants were generated and randomized to receive ruxolitinib or vehicle control.

RESULTS

The most common grade 3/4 treatment-related toxicities observed were anemia (10%) and thrombocytopenia (6%). The clinical overall response rate was 38% by MDS/MPN IWG criteria and 43% of patients with baseline splenomegaly achieved a spleen response. Profiling of cytokine levels and somatic mutations at baseline failed to identify predictive biomarkers. PDX models derived from screening samples of study participants recapitulated responses seen in humans, particularly spleen responses, and corroborated ruxolitinib's clinical efficacy in a randomized murine study not feasible in human trials.

CONCLUSIONS

Ruxolitinib demonstrated clinical efficacy and an acceptable adverse event profile in patients with CMML, identifying a potential novel therapeutic in this rare malignancy. Furthermore, this study demonstrates proof of concept that PDX modeling can recapitulate responses of patients treated on clinical trial and represents a novel correlative study that corroborates clinical efficacy seen in humans.

Randomized, Single-Blind, Multicenter Phase II Study of Two Doses of Imetelstat in Relapsed or Refractory Myelofibrosis

PURPOSE

Patients with myelofibrosis who are relapsed or refractory (R/R) to Janus-associated kinase inhibitors (JAKis) have poor clinical outcomes including dismal overall survival (OS) that ranges between 13 and 16 months. Imetelstat, a telomerase inhibitor, was evaluated in patients with intermediate-2 or high-risk myelofibrosis R/R to JAKi in a phase II multicenter study (ClinicalTrials.gov identifier: NCT02426086).

PATIENTS AND METHODS

Patients were randomly assigned to receive either imetelstat 9.4 mg/kg or 4.7 mg/kg intravenous once every 3 weeks. Spleen response (≥ 35% spleen volume reduction) and symptom response (≥ 50% reduction in total symptom score) rates at week 24 were coprimary end points. Secondary end points included OS and safety.

RESULTS

Study enrollment was closed early, and patients treated with 4.7 mg/kg were permitted to continue treatment with 9.4 mg/kg. At week 24, spleen and symptom response rates were 10.2% and 32.2% in the 9.4-mg/kg arm and 0% and 6.3% in the 4.7-mg/kg arm. Treatment with imetelstat 9.4 mg/kg led to a median OS of 29.9 months and bone marrow fibrosis improvement in 40.5% and variant allele frequency reduction of driver mutations in 42.1% of evaluable patients. Fibrosis improvement and variant allele frequency reduction correlated with OS. Target inhibition was demonstrated by reduction of telomerase activity and human telomerase reverse transcriptase level and correlated with spleen response, symptom response, and OS. Most common adverse events on both arms were grade 3 or 4 reversible cytopenias.

CONCLUSION

In this phase II study of two imetelstat doses, 9.4 mg/kg once every 3 weeks demonstrated clinical benefits in symptom response rate, with an acceptable safety profile for this poor-risk JAKi R/R population. Biomarker and bone marrow fibrosis assessments suggested selective effects on the malignant clone. A confirmatory phase III study is currently underway.

IMerge: A phase 3 study to evaluate imetelstat in transfusion-dependent subjects with IPSS low or intermediate-1 risk myelodysplastic syndromes that are relapsed/refractory to erythropoiesis-stimulating agent treatment

TPS7056

Background: Current treatment options for red blood cell (RBC) transfusion-dependent (TD) patients (pts) with lower risk (LR) myelodysplastic syndromes (MDS) relapsed after or refractory to erythropoiesis-stimulating agents (ESAs) have limited efficacy and durability; new approaches are needed. Imetelstat is a first-in-class telomerase inhibitor that targets cells with short telomeres and active telomerase, characteristics observed in MDS pts across all disease stages. IMerge (MDS3001) is a Phase 2/3 global study of imetelstat for TD pts with non-del(5q) LR MDS post ESA therapy. The results from Phase 2 part indicated that imetelstat achieved durable RBC transfusion independence (RBC-TI) and the most frequently reported adverse events were manageable and reversible grade ≥3 cytopenias. Among 38 pts with median follow-up of 24 months, 8-week, 24-week and 1-year TI rates were 42%, 32% and 29%, respectively; these responses were seen across different LR MDS subtypes. Median TI duration was 20 months and the longest TI was 2.7 years. A high and durable hematologic improvement-erythroid (HI-E) rate of 68% for a median duration of 21 months were also achieved. Reduction of variant allele frequency of mutations by imetelstat treatment was observed in some pts and correlated with clinical benefits (Platzbecker et al EHA 2020; Steensma et al JCO 2020). These results support the Phase 3 part of the trial. Methods: IMerge is two-part, Phase 2/3 study (ClinicalTrials.gov: NCT02598661). The Phase 3 part of the study is open for enrollment to adult pts with International Prognostic Scoring System (IPSS) low or intermediate-1 risk, non-del(5q) MDS who are TD, are relapsed after or refractory to ESAs, and have not received treatment with lenalidomide or hypomethylating agents. The study is a randomized (2:1) double-blind, placebo-controlled trial to compare efficacy of imetelstat vs placebo that will enroll approximately 170 pts and will be conducted at approximately 120 centers in North America, Europe, Asia and Middle East. Imetelstat is administered as 2-hour IV infusion every 4 weeks at 7.5 mg/kg. The primary endpoint of the study is to assess the rate of RBC-TI lasting ≥8 weeks. Secondary endpoints include safety, rate of RBC-TI ≥24 weeks, time to RBC-TI start, RBC-TI duration, rate of HI-E, the amount and relative change in RBC transfusions, rate of CR or PR, overall survival, progression of MDS, pharmacokinetics, and quality of life. Biomarkers relevant to the mechanism of action of imetelstat will be assessed to demonstrate target inhibition and their association with clinical responses. Cytogenetics and mutation analyses will be performed to evaluate the impact of imetelstat on reduction/depletion of malignant clones leading to disease modification. The study is currently recruiting pts. Clinical trial information: NCT02598661.

Molecular annotation of extramedullary acute myeloid leukemia to identify prevalence of targetable mutations

7024

Background: Extramedullary (EM) involvement, including myeloid sarcoma (MS) and leukemia cutis (LC), is uncommon in patients with acute myeloid leukemia (AML). Mutational landscape of EM-AML is not well characterized, including concordance of sequencing data from EM vs. non-EM site (blood or bone marrow) and the potential for personalized targeted therapy in this patient cohort. Methods: In a multicenter retrospective study, clinical and genomic data were collected on EM-AML patients treated at Moffitt Cancer Center, Memorial Healthcare System, and University of Miami, as well as sequenced cases at a central laboratory. Next generation sequencing (NGS) data come from panels that interrogated 24- 406 genes, with 15 genes covered by all panels, including notably, IDH1, IDH2, KIT, KRAS, NPM1, NRAS, and TP53. Survival estimates using Kaplan-Meier statistics and multivariate analysis with Cox-regression were performed in SPSS (v.26). Results: Our study included 58 patients with EM-AML. Median age at diagnosis was 62 years; 55% of patients were males. In our cohort, 34 (59%) patients had MS, and 19 (33%) had LC. EM-AML was noted during relapse in 60% of evaluable patients (n=45), and 31% had isolated EM disease. Patients with LC had a significantly worse median overall survival (OS) than those with MS (5.7 months vs. 21.9 months, p= 0.008); Pattern of EM involvement (MS vs. LC) remained an independent prognostic factor for OS (p= 0.04) in a multivariate analysis including disease setting (new diagnosis vs. relapse) and ELN risk category. Results of NGS performed during EM presentation were available in 48 patients, 19 of which had NGS data from EM site. Most commonly mutated genes were NRAS on EM site NGS (37%) and NPM1 on non-EM site NGS (28%). Based on EM NGS, 52% patients had a targetable genomic alteration, with 37% mutations in IDH, 21% NPM1, 5% FLT3, and 11% MLL-PTD. Five (two with concurrent M+EM disease) out of nine evaluable patients had significant discordance in targetable mutations between EM and non-EM NGS at EM-AML. Three of four patients who received treatment with IDH1/2 inhibitors based on EM NGS achieved complete response. Conclusions: EM-AML has a distinct molecular architecture with an inferior OS in LC vs. MS patients. We conclude that EM site NGS is critical in patients with EM-AML, as 52% have potentially targetable mutations and could benefit from specific targeted therapies.[Table: see text]

Health-related quality of life (HRQoL) in patients (pts) with myelodysplastic syndromes (MDS) in the Connect Myeloid Disease Registry

7040

Background: At diagnosis, disease risk and transfusion burden (TB) can impact HRQoL in pts with MDS. The impact of disease status and higher transfusion requirements on HRQoL has not been well studied. We used data from the Connect Myeloid Disease Registry, an ongoing, prospective, observational cohort study that includes adult pts with lower-risk (LR) and higher-risk (HR) MDS, to investigate factors influencing baseline (BL) and subsequent HRQoL. Methods: BL and Month 6 (M6) data from pts enrolled from Dec 12, 2013 to Mar 6, 2020 (data cutoff) were analyzed. Pts were stratified by International Prognostic Scoring System (IPSS) risk (LR, HR), treatment (Tx) within 45 days post-enrollment (no Tx, best supportive care [BSC], active Tx), and TB 16 weeks post-BL (non-transfusion dependent [NTD], low TB [LTB]; 1−3 transfusions, high TB [HTB]: ≥4 transfusions). Pts completed EQ-5D, FACT-An trial outcome index (TOI), and FACT-Fatigue (FACT-F) questionnaires at BL and quarterly thereafter. Clinically meaningful change, based on minimally important differences, was defined as a change of ±0.07 for EQ-5D, ±6 for FACT-An TOI, and ±3 for FACT-F. Results: At data cutoff, 830 (489 LR, 341 HR) pts were enrolled. Median age was 74 years. 278 pts received no initial Tx, 161 BSC, and 378 active Tx. At BL, 470 were NTD, 197 LTB, and 163 HTB. Of 670 pts still on-study at M6, 462 completed the questionnaires at both BL and M6. At BL , clinically meaningful differences were observed in FACT-An TOI and FACT-F scores, but not EQ-5D, between LR- and HR-MDS and the Tx subgroups . From BL to M6, no clinically meaningful changes were observed in mean scores for each questionnaire. For the TB subgroups, meaningful differences were observed at BL in FACT-An TOI and FACT-F scores, but not EQ-5D (Table). From BL to M6, meaningful decreases in scores were reported by 26%, 30%, and 35% of NTD, LTB, and HTB pts in EQ-5D, 41%, 43%, and 48% for FACT-An TOI, and 40%, 42%, and 48% for FACT-F; increases were reported by 19%, 19%, and 20% pts for EQ-5D, 31%, 32%, and 39% for FACT-An TOI, and 30%, 39%, and 40% for FACT-F. Conclusions: This preliminary analysis suggests that pts with HR-MDS, and transfusion-dependent pts, generally had worse HRQoL at BL, providing further support to initiating active Tx in pts with TB. Possible limitations of the analysis are lower completion rates in pts with more severe disease, and EQ-5D may not capture changes in these subgroups at M6. A longer follow-up may help delineate the impact of Tx on HRQoL assessments in pts with MDS. Clinical trial information: NCT01688011. [Table: see text]

Using tissue microarray to detect inflammasome signaling components that contribute to the pathogenesis of myelodysplastic syndrome

7044

Background: Myelodysplastic syndromes (MDS) are characterized by aberrant maturation, ineffective hematopoiesis, cytopenia, and progression to acute myeloid leukemia. MDS pathogenesis is multifactorial and potentially linked to constitutive innate immune stimulation converging upon the NLRP3 inflammasome to induce pyroptosis, a caspase-1 dependent cell death. Inflammasome assembly is initiated by both cell-extrinsic stimuli including S100A9, the TLR4 and CD33 ligand, and cell-intrinsic danger signals licensing caspase-1 which activates IL1b and beta-catenin resulting in cell death and cellular proliferation leading to maturation and differentiation blocks. Further, EYA2 has been suggested to be an inflammasome activator, whereas cPLA2 has been suggested to be an inhibitor. The purpose of this study is to determine whether immunohistochemistry (IHC) may be utilized to assess expression of inflammasome components. Methods: An IRB protocol was approved prior to initiating this study. We retrospectively identified 43 low risk MDS patients. A tissue microarray (TMA) was constructed utilizing MDS bone marrow biopsy samples (2-3 representative cores per sample). IL-1, S100A9, EYA2, cPLA2, beta-catenin, and TLR4 expression were assessed by IHC after validation of each antibody. IHC expression was scored independently by two hematopathologists by calculating scores (product of staining intensity x percent expression). IHC expression was compared using Spearman correlation estimate. Demographic and clinical data were collected and correlated with IHC expression using Kruskal-Wallis test, Spearman correlation, and Logrank test. Results: Patients were median 72 years of age, 67% men and included 47% MDS-MLD, 35% MDS-RS, 14% MDS-SLD, 2% MDS del5q and 2% MDS-U. IL-1 expression correlated with beta-catenin expression, r = 0.42, 95% CI 0.115 to 0.658 (p = 0.007). There was a trend towards significance between IL-1 and cPLA2, r = 0.30 (p = 0.067); S100A9 and cPLA2, r = 0.31 (p = 0.052); and S100A9 and EYA2, r = 0.31 (p = 0.057). Percentage EYA2 expression correlated with blast count, r = 0.425 (p = 0.008). The IHC expression of these antigens did not correlate with WHO MDS subclassification, IPSS, R-IPSS, disease progression, or survival (p > 0.05). Conclusions: IHC staining of inflammasome activators using TMA may allow better characterization of molecular pathways contributing the MDS pathogenesis. A correlation was seen between expression of antigens known to be increased downstream of NLRP3 inflammasome activation. Furthermore, increased expression of EYA2 correlated with blast count. A future study will compare expression patterns between normal, low risk MDS and high risk MDS samples and correlate these findings with clinical outcome data to further elucidate the pathogenesis of MDS and identify potential targetable markers for novel therapeutic strategies.

Outcomes of IDH1/2 mutant AML patients treated with IDH1/2 inhibitors: A single institutional experience

e19010

Background: Recent studies showed that IDH1/2 are frequently mutated in AML and that aberrant 2-HG elevation driven by the mutant IDH1/2 proteins plays a pivotal role in AML development. Subsequent clinical trials of IDH1/2 inhibitors demonstrated promising outcomes in IDH1/2mut AML patients. In this single institutional retrospective study, we explored the efficacy and safety outcomes of IDH1/2mut AML patients treated with Ivosidenib or Enasidenib. Methods: We retrospectively identified AML patients who had IDH1/2 somatic mutations based on NGS assessments. Clinical and demographic data were extracted from the medical records. Statistical analyses were performed using GraphPad Prism (v.7.03) and SPSS (v.24.0). Results: A total of 43 ( IDH1mut, n = 12; IDH2mut, n = 33; both IDH1/2mut, n = 2) patients were included in the study. Median age at AML diagnosis was 67.6 (24.2-83.3) years and 24 (55.8%) patients were male. Eighteen (42%) patients had secondary AML and 13 (34.2%), 17 (44.7%), and 8 (21.1%) patients had favorable, intermediate, and adverse risk, respectively. A total of 23 (53.5%) and 9 (20.9%) patients received intensive chemotherapy and hypomethylating agents as their 1st line therapy. One patient received Enasidenib as the 1st line therapy and the rest of the patients had relapsed/refractory disease prior to IDH1/2 inhibitor therapy. Median number of treatment prior to IDH1/2 inhibitors was 4 (0-8). The median duration of IDH1/2 inhibitor treatment was 3.2 (0.2-31.6) months ( IDH1 mut, 2.5 [0.7-13.5]; IDH2 mut, 3.4 [0.2-31.6]). Treatment response was assessed in 38 patients and 18 had overall response (CR, n = 7 [18.4%]; PR, n = 11 [28.9%]). Among these, 13 patients had concurrent somatic mutations in FLT3, KRAS, NRAS, or PTPN11. The overall response rate in these patients was not statistically different compared to patients who did not have these mutations (38.5% vs. 40%, p > 0.05). The median PFS was 3.9 (0.4-14.7) months ( IDH1 mut, 5.6 [1.7-11.5] vs. IDH2 mut, 3.7 [0.4-14.7], p > 0.05) and median OS was 7.6 (0.4-44.1) months. The most common reason for IDH1/2 inhibitor discontinuation was disease progression (n = 21) followed by adverse events (n = 3) and allogeneic transplant (n = 2). The adverse events were assessed in 41 patients and the most common adverse events were differentiation syndrome ( IDH1 mut, n = 3; IDH2 mut, n = 5) and leukocytosis ( IDH1 mut, n = 4; IDH2 mut, n = 4) followed by hepatic toxicity ( IDH2 mut n = 7), and QTc prolongation ( IDH1 mut, n = 3). Conclusions: Our study indicates that IDH1/2 inhibitors remain a reasonable option for the refractory/relapsed IDH1/2mut AML. However, significant number of patients failed to show any response and many of the patients who showed initial response had short response duration. These findings warrant further studies to identify underlying resistance mechanisms of IDH1/2 inhibitors and the optimal combination therapeutic strategies.

Eprenetapopt (APR-246) and Azacitidine in TP53-Mutant Myelodysplastic Syndromes

PURPOSE

Approximately 20% of patients with TP53-mutant myelodysplastic syndromes (MDS) achieve complete remission (CR) with hypomethylating agents. Eprenetapopt (APR-246) is a novel, first-in-class, small molecule that restores wild-type p53 functions in TP53-mutant cells.

METHODS

This was a phase Ib/II study to determine the safety, recommended phase II dose, and efficacy of eprenetapopt administered in combination with azacitidine in patients with TP53-mutant MDS or acute myeloid leukemia (AML) with 20%-30% marrow blasts (ClinicalTrials.gov identifier: NCT03072043).

RESULTS

Fifty-five patients (40 MDS, 11 AML, and four MDS/myeloproliferative neoplasms) with at least one TP53 mutation were treated. The overall response rate was 71% with 44% achieving CR. Of patients with MDS, 73% (n = 29) responded with 50% (n = 20) achieving CR and 58% (23/40) a cytogenetic response. The overall response rate and CR rate for patients with AML was 64% (n = 7) and 36% (n = 4), respectively. Patients with only TP53 mutations by next-generation sequencing had higher rates of CR (69% v 25%; P = .006). Responding patients had significant reductions in TP53 variant allele frequency and p53 expression by immunohistochemistry, with 21 (38%) achieving complete molecular remission (variant allele frequency < 5%). Median overall survival was 10.8 months with significant improvement in responding versus nonresponding patients by landmark analysis (14.6 v 7.5 months; P = .0005). Overall, 19/55 (35%) patients underwent allogeneic hematopoietic stem-cell transplant, with a median overall survival of 14.7 months. Adverse events were similar to those reported for azacitidine or eprenetapopt monotherapy, with the most common grade ≥ 3 adverse events being febrile neutropenia (33%), leukopenia (29%), and neutropenia (29%).

CONCLUSION

Combination treatment with eprenetapopt and azacitidine is well-tolerated yielding high rates of clinical response and molecular remissions in patients with TP53-mutant MDS and oligoblastic AML.