A phase 1 study of the irreversible FLT3 inhibitor FF-10101 in relapsed or refractory acute myeloid leukemia.

FLT3 tyrosine kinase inhibitors (TKIs) have clinical efficacy for patients with FLT3-mutated AML (acute myeloid leukemia), but their impact is limited by resistance in the setting of monotherapy and by tolerability problems when used in combination therapies. FF-10101 is a novel compound that covalently binds to a cysteine residue near the active site of FLT3, irreversibly inhibiting receptor signaling. It is effective against most FLT3 activating mutations, and unlike other inhibitors is minimally vulnerable to resistance induced by FLT3 ligand (FL). We conducted a phase 1 dose escalation study of oral FF-10101 (NCT03194685) in patients with relapsed and/or refractory AML, the majority of whom harbored FLT3-activating mutations and/or had prior exposure to FLT3 inhibitors. Fifty-four participants enrolled in cohorts ranging from 10 to 225 mg per day and 50 to 100 mg twice daily (BID). The dose limiting toxicities (DLT) were diarrhea and QT prolongation. Among 40 response-evaluable participants, the composite complete response rate was 10%, and the overall response rate (including partial responses) was 12.5%, including patients who had progressed on gilteritinib. 56% of participants had prior exposure to FLT3 inhibitors. The recommended phase 2 dose (RP2D) was 75 mg BID. FF-10101 potentially represents a next-generation advance in the management of FLT3-mutated AML.

Treatment of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN): focus on the use of tagraxofusp and clinical considerations.

BPDCN is an aggressive myeloid malignancy with a poor prognosis. It derives from the precursors of plasmacytoid dendritic cells and is characterized by CD123 overexpression, which is seen in all patients with BPDCN. The CD123-directed therapy tagraxofusp is the only approved treatment for BPDCN; it was approved in the US as monotherapy for the treatment of patients aged ≥2 years with treatment-naive or relapsed/refractory BPDCN. Herein, we review the available data supporting the utility of tagraxofusp in treating patients with BPDCN. In addition, we present best practices and real-world insights from clinicians in academic and community settings in the US on how they use tagraxofusp to treat BPDCN. Several case studies illustrate the efficacy of tagraxofusp and discuss its safety profile, as well as the prevention, mitigation, and management of anticipated adverse events.

Pivekimab sunirine (IMGN632), a novel CD123-targeting antibody-drug conjugate, in relapsed or refractory acute myeloid leukaemia: a phase 1/2 study.

BACKGROUND: Pivekimab sunirine (IMGN632) is a first-in-class antibody-drug conjugate comprising a high-affinity CD123 antibody, cleavable linker, and novel indolinobenzodiazepine pseudodimer payload. CD123 is overexpressed in several haematological malignancies, including acute myeloid leukaemia. We present clinical data on pivekimab sunirine in relapsed or refractory acute myeloid leukaemia. METHODS: This first-in-human, phase 1/2 dose-escalation and dose-expansion study enrolled participants aged 18 years or older at nine hospitals in France, Italy, Spain, and the USA with CD123+ haematological malignancies (Eastern Cooperative Oncology Group performance status of 0-1); participants reported here were in a cohort of participants with acute myeloid leukaemia who were refractory to or had relapsed on one or more previous treatments for acute myeloid leukaemia. The 3 + 3 dose-escalation phase evaluated two dosing schedules: schedule A (once every 3 weeks, on day 1 of a 3-week cycle) and fractionated schedule B (days 1, 4, and 8 of a 3-week cycle). The dose-expansion phase evaluated two cohorts: one cohort given 0·045 mg/kg of bodyweight (schedule A) and one cohort given 0·090 mg/kg of bodyweight (schedule A). The primary endpoints were the maximum tolerated dose and the recommended phase 2 dose. Antileukaemia activity (overall response and a composite complete remission assessment) was a secondary endpoint. The study is ongoing and registered with ClinicalTrials.gov, NCT03386513. FINDINGS: Between Dec 29, 2017, and May 27, 2020, 91 participants were enrolled (schedule A, n=68; schedule B, n=23). 30 (44%) of schedule A participants were female and 38 (56%) were male; 60 (88%) were White, six (9%) were Black or African American, and two (3%) were other races. Pivekimab sunirine at doses of 0·015 mg/kg to 0·450 mg/kg in schedule A was administered in six escalating doses with no maximum tolerated dose defined; three dose-limiting toxicities were observed (reversible veno-occlusive disease; 0·180 mg/kg, n=1 and 0·450 mg/kg, n=1; and neutropenia; 0·300 mg/kg, n=1). Schedule B was not pursued further on the basis of comparative safety and antileukaemia findings with schedule A. The recommended phase 2 dose was selected as 0·045 mg/kg once every 3 weeks. At the recommended phase 2 dose (n=29), the most common grade 3 or worse treatment-related adverse events were febrile neutropenia (three [10%]), infusion-related reactions (two [7%]), and anaemia (two [7%]). Treatment-related serious adverse events occurring in 5% or more of participants treated at the recommended phase 2 dose were febrile neutropenia (two [7%]) and infusion-related reactions (two [7%]). Among 68 participants who received schedule A, one death (1%) was considered to be treatment-related (cause unknown; 0·300 mg/kg cohort). At the recommended phase 2 dose, the overall response rate was 21% (95% CI 8-40; six of 29) and the composite complete remission rate was 17% (95% CI 6-36; five of 29). INTERPRETATION: Pivekimab sunirine showed single-agent activity across multiple doses, with a recommended phase 2 dose of 0·045 mg/kg once every 3 weeks. These findings led to a phase 1b/2 study of pivekimab sunirine plus azacitidine and venetoclax in patients with CD123-positive acute myeloid leukaemia. FUNDING: ImmunoGen.

Crenolanib and Intensive Chemotherapy in Adults With Newly Diagnosed FLT3-Mutated AML.

PURPOSE: Crenolanib is a second-generation tyrosine kinase inhibitor with activity against FLT3-ITD- and TKD-mutant AML. We conducted a trial of crenolanib plus intensive chemotherapy in adults with newly diagnosed FLT3-mutant AML. METHODS: Eligible patients were 18 years and older. Induction chemotherapy consisted of cytarabine (100 mg/m2) continuous infusion on days 1-7 and anthracycline (daunorubicin 60-90 mg/m2 or idarubicin 12 mg/m2, once daily) on days 1-3 followed by consolidation with high-dose cytarabine (1-3 g/m2 twice daily on days 1, 3, 5) and/or allogeneic transplant. Crenolanib (100 mg thrice a day) was given from day 9 until 72 hours before the next cycle, after consolidation, and for 12 months after consolidation or transplant. RESULTS: Forty-four patients (median age, 57; range, 19-75 years) were enrolled. Thirty-six had FLT3-ITD, and 11 had FLT3-TKD mutations. European LeukemiaNet 2017 disease risk was favorable in 34%, intermediate in 30%, and adverse in 36%. The overall response rate was 86% (complete remission [CR], 77%; CR with incomplete count recovery [CRi], 9%): 90% in patients 60 years and younger and 80% in older patients. Measurable residual disease-negative CR/CRi rates were 89% and 45%, respectively. With a 45-month follow-up, median overall survival has not been reached and the median event-free survival was 44.7 months. Among younger patients, the estimated 3-year survival was 71.4% with 15% cumulative incidence of relapse. Treatment-related serious adverse events included febrile neutropenia, diarrhea, and nausea. The median time to platelets ≥100,000/µL and absolute neutrophil count ≥1,000/µL during induction was 29 and 32 days, respectively. No new FLT3-mutant clones were detected at relapse in patients completing consolidation. CONCLUSION: Crenolanib plus intensive chemotherapy in adults with newly diagnosed FLT3-mutant AML results in high rate of deep responses and long-term survival with acceptable toxicity. A randomized trial of crenolanib versus midostaurin plus chemotherapy in younger patients is ongoing.

Phase 2 study of add-on parsaclisib for patients with myelofibrosis and suboptimal response to ruxolitinib: final results.

ABSTRACT: Ruxolitinib reduces spleen volume, improves symptoms, and increases survival in patients with intermediate- or high-risk myelofibrosis. However, suboptimal response may occur, potentially because of signaling via the phosphoinositide 3-kinase (PI3K)/protein kinase B pathway. This phase 2 study evaluated dosing, efficacy, and safety of add-on PI3Kδ inhibitor parsaclisib for patients with primary or secondary myelofibrosis with suboptimal response to ruxolitinib. Eligible patients remained on a stable ruxolitinib dose and received add-on parsaclisib 10 or 20 mg, once daily for 8 weeks, and once weekly thereafter (daily-to-weekly dosing; n = 32); or parsaclisib 5 or 20 mg, once daily for 8 weeks, then 5 mg once daily thereafter (all-daily dosing; n = 42). Proportion of patients achieving a ≥10% decrease in spleen volume at 12 weeks was 28% for daily-to-weekly dosing and 59.5% for all-daily dosing. Proportions of patients achieving ≥50% decrease at week 12 in Myelofibrosis Symptom Assessment Form and Myeloproliferative Neoplasms Symptom Assessment Form symptom scores were 14% and 18% for daily-to-weekly dosing, and 28% and 32% for all-daily dosing, respectively. Most common nonhematologic treatment-emergent adverse events were nausea (23%), diarrhea (22%), abdominal pain and fatigue (each 19%), and cough and dyspnea (each 18%). New-onset grade 3 and 4 thrombocytopenia were observed in 19% of patients, each dosed daily-to-weekly, and in 26% and 7% of patients dosed all-daily, respectively, managed with dose interruptions. Hemoglobin levels remained steady. The addition of parsaclisib to stable-dose ruxolitinib can reduce splenomegaly and improve symptoms, with manageable toxicity in patients with myelofibrosis with suboptimal response to ruxolitinib. This trial was registered at www.clinicaltrials.gov as #NCT02718300.

Spliceosome mutations are associated with clinical response in a phase 1b/2 study of the PLK1 inhibitor onvansertib in combination with decitabine in relapsed or refractory acute myeloid leukemia.

PLK1 is overexpressed in acute myeloid leukemia (AML). A phase 1b trial of the PLK1 inhibitor onvansertib (ONV) combined with decitabine (DAC) demonstrated initial safety and efficacy in patients with relapsed/refractory (R/R) AML. The current study aimed to identify molecular predictors of response to ONV + DAC in R/R AML patients. A total of 44 R/R AML patients were treated with ONV + DAC and considered evaluable for efficacy. Bone marrow (BM) samples were collected at baseline for genomic and transcriptomic analysis (n = 32). A 10-gene expression signature, predictive of response to ONV + DAC, was derived from the leading-edge genes of gene set enrichment analyses (GSEA). The gene signature was evaluated in independent datasets and used to identify associated mutated genes. Twenty percent of the patients achieved complete remission, with or without hematologic count recovery (CR/CRi), and 32% exhibited a ≥50% reduction in bone marrow blasts. Patients who responded to treatment had elevated mitochondrial function and OXPHOS. The gene signature was not associated with response to DAC alone in an independent dataset. By applying the signature to the BeatAML cohort (n = 399), we identified a positive association between predicted ONV + DAC response and mutations in splicing factors (SF). In the phase 1b/2 trial, patients with SF mutations (SRSF2, SF3B1) had a higher CR/CRi rate (50%) compared to those without SF mutations (9%). PLK1 inhibition with ONV in combination with DAC could be a potential therapy in R/R AML patients, particularly those with high OXPHOS gene expression and SF mutations.

Tolerability and Efficacy of the Anticluster of Differentiation 47 Antibody Magrolimab Combined With Azacitidine in Patients With Previously Untreated AML: Phase Ib Results.

PURPOSE: Magrolimab is a first-in-class humanized monoclonal antibody against cluster of differentiation 47, an antiphagocytic signal used by cancer cells to evade phagocytosis. Azacitidine upregulates prophagocytic signals on AML cells, further increasing phagocytosis when combined with magrolimab. We report final phase Ib data for magrolimab with azacitidine in patients with untreated AML ineligible for intensive chemotherapy (ClinicalTrials.gov identifier: NCT03248479). PATIENTS AND METHODS: Patients with previously untreated AML, including TP53-mutant AML, received magrolimab intravenously as an initial dose (1 mg/kg, days 1 and 4), followed by 15 mg/kg once on day 8 and 30 mg/kg once weekly or every 2 weeks as maintenance. Azacitidine 75 mg/m2 was administered intravenously/subcutaneously once daily on days 1-7 of each 28-day cycle. Primary end points were safety/tolerability and proportion with complete remission (CR). RESULTS: Eighty-seven patients were enrolled and treated; 72 (82.8%) had TP53 mutations with a median variant allele frequency of 61% (range, 9.8-98.7). Fifty-seven (79.2%) of TP53-mutant patients had European LeukemiaNet 2017 adverse-risk cytogenetics. Patients received a median of 4 (range, 1-39) cycles of treatment. The most common treatment-emergent adverse events included constipation (49.4%), nausea (49.4%), and diarrhea (48.3%). Thirty (34.5%) experienced anemia, and the median hemoglobin change from baseline to first postdose assessment was -0.9 g/dL (range, -3.6 to 2.5 g/dL). Twenty-eight (32.2%) patients achieved CR, including 23 (31.9%) patients with TP53 mutations. The median overall survival in TP53-mutant and wild-type patients were 9.8 months and 18.9 months, respectively. CONCLUSION: Magrolimab with azacitidine was relatively well tolerated with promising efficacy in patients with AML ineligible for intensive induction chemotherapy, including those with TP53 mutations, warranting further evaluation of magrolimab with azacitidine in AML. The phase III randomized ENHANCE-2 (ClinicalTrials.gov identifier: NCT04778397) and ENHANCE-3 (ClinicalTrials.gov identifier: NCT05079230) studies are recruiting frontline patients with AML.

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.

Acute myeloid leukemia with LRRFIP1::FGFR1 rearrangement and a complex karyotype.

We report a case of a 20-year-old man who presented with splenomegaly, hyperleukocytosis, anemia, and thrombocytopenia. A diagnosis of acute myeloid leukemia (AML) with LRRFIP1::FGFR1 rearrangement with complex karyotype was determined. Chromosome analysis showed a male karyotype: 46,XY,i(1)(q10),t(2;8)(q37;p11.2),der(5)t(1;5) (p22;q13)[17]46,XY[3]. Fluorescence in situ hybridization (FISH) analysis using the Cytocell FGFR1 break apart/amplification probe detected FGFR1 rearrangement with t(2:8) in 126/200 cells analyzed. Other FISH probes including 1p36/ 1q25 probes, del(5q) deletion probe, TLX3 break apart probe, and PDGFRB break apart probe were also utilized to confirm the other karyotypic abnormalities. Next-generation sequencing (NGS) SureSelectXT Custom DNA Target Somatic Detection detected RUNX1 gene mutation. NGS Archer FusionPlex (RNA) confirmed the LRRFIP1::FGFR1 rearrangement. This is the second reported case of AML with LRRFIP1::FGFR1 rearrangement and the first with a complex karyotype.

Magrolimab in Combination With Azacitidine in Patients With Higher-Risk Myelodysplastic Syndromes: Final Results of a Phase Ib Study.

PURPOSE: Magrolimab is a monoclonal antibody that blocks cluster of differentiation 47, a don't-eat-me signal overexpressed on cancer cells. Cluster of differentiation 47 blockade by magrolimab promotes macrophage-mediated phagocytosis of tumor cells and is synergistic with azacitidine, which increases expression of eat-me signals. We report final phase Ib data in patients with untreated higher-risk myelodysplastic syndromes (MDS) treated with magrolimab and azacitidine (ClinicalTrials.gov identifier: NCT03248479). PATIENTS AND METHODS: Patients with previously untreated Revised International Prognostic Scoring System intermediate-/high-/very high-risk MDS received magrolimab intravenously as a priming dose (1 mg/kg) followed by ramp-up to a 30 mg/kg once-weekly or once-every-2-week maintenance dose. Azacitidine 75 mg/m2 was administered intravenously/subcutaneously once daily on days 1-7 of each 28-day cycle. Primary end points were safety/tolerability and complete remission (CR) rate. RESULTS: Ninety-five patients were treated. Revised International Prognostic Scoring System risk was intermediate/high/very high in 27%, 52%, and 21%, respectively. Fifty-nine (62%) had poor-risk cytogenetics and 25 (26%) had TP53 mutation. The most common treatment-emergent adverse effects included constipation (68%), thrombocytopenia (55%), and anemia (52%). Median hemoglobin change from baseline to first postdose assessment was -0.7 g/dL (range, -3.1 to +2.4). CR rate and overall response rate were 33% and 75%, respectively. Median time to response, duration of CR, duration of overall response, and progression-free survival were 1.9, 11.1, 9.8, and 11.6 months, respectively. Median overall survival (OS) was not reached with 17.1-month follow-up. In TP53-mutant patients, 40% achieved CR with median OS of 16.3 months. Thirty-four patients (36%) had allogeneic stem-cell transplant with 77% 2-year OS. CONCLUSION: Magrolimab + azacitidine was well tolerated with promising efficacy in patients with untreated higher-risk MDS, including those with TP53 mutations. A phase III trial of magrolimab/placebo + azacitidine is ongoing (ClinicalTrials.gov identifier: NCT04313881 [ENHANCE]).

KDM6B protects T-ALL cells from NOTCH1-induced oncogenic stress.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematopoietic neoplasm resulting from the malignant transformation of T-cell progenitors. While activating NOTCH1 mutations are the dominant genetic drivers of T-ALL, epigenetic dysfunction plays a central role in the pathology of T-ALL and can provide alternative mechanisms to oncogenesis in lieu of or in combination with genetic mutations. The histone demethylase enzyme KDM6A (UTX) is also recurrently mutated in T-ALL patients and functions as a tumor suppressor. However, its gene paralog, KDM6B (JMJD3), is never mutated and can be significantly overexpressed, suggesting it may be necessary for sustaining the disease. Here, we used mouse and human T-ALL models to show that KDM6B is required for T-ALL development and maintenance. Using NOTCH1 gain-of-function retroviral models, mouse cells genetically deficient for Kdm6b were unable to propagate T-ALL. Inactivating KDM6B in human T-ALL patient cells by CRISPR/Cas9 showed KDM6B-targeted cells were significantly outcompeted over time. The dependence of T-ALL cells on KDM6B was proportional to the oncogenic strength of NOTCH1 mutation, with KDM6B required to prevent stress-induced apoptosis from strong NOTCH1 signaling. These studies identify a crucial role for KDM6B in sustaining NOTCH1-driven T-ALL and implicate KDM6B as a novel therapeutic target in these patients.

CYAD-01, an autologous NKG2D-based CAR T-cell therapy, in relapsed or refractory acute myeloid leukaemia and myelodysplastic syndromes or multiple myeloma (THINK): haematological cohorts of the dose escalation segment of a phase 1 trial.

BACKGROUND: CYAD-01 is an autologous chimeric antigen receptor (CAR) T-cell product based on the natural killer (NK) group 2D (NKG2D) receptor, which binds eight ligands that are overexpressed in a wide range of haematological malignancies but are largely absent on non-neoplastic cells. Initial clinical evaluation of a single infusion of CYAD-01 at a low dose in patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, and multiple myeloma supported the feasibility of the approach and prompted further evaluation of CYAD-01. The aim of the present study was to determine the safety and recommended phase 2 dosing of CYAD-01 administered without preconditioning or bridging chemotherapy. METHODS: The multicentre THINK study was an open-label, dose-escalation, phase 1 study for patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, or multiple myeloma, after at least one previous line of therapy. Patients were recruited from five hospitals in the USA and Belgium. The dose-escalation segment evaluated three dose levels: 3 × 108 (dose level one), 1 × 109 (dose level two), and 3 × 109 (dose level three) cells per infusion with a 3 + 3 Fibonacci study design using a schedule of three infusions at 2-week intervals followed by potential consolidation treatment consisting of three additional infusions. The occurrence of dose-limiting toxicities post-CYAD-01 infusion was assessed as the primary endpoint in the total treated patient population. The trial was registered with ClinicalTrials.gov, NCT03018405, and EudraCT, 2016-003312-12, and has been completed. FINDINGS: Between Feb 6, 2017, and Oct 9, 2018, 25 patients were registered in the haematological dose-escalation segment. Seven patients had manufacturing failure for insufficient yield and two had screening failure. 16 patients were treated with CYAD-01 (three with multiple myeloma and three with acute myeloid leukaemia at dose level one; three with acute myeloid leukaemia at dose level two; and six with acute myeloid leukaemia and one with myelodysplastic syndromes at dose level three). Median follow-up was 118 days (IQR 46-180). Seven patients (44%) had grade 3 or 4 treatment-related adverse events. In total, five patients (31%) had grade 3 or 4 cytokine release syndrome across all dose levels. One dose-limiting toxicity of cytokine release syndrome was reported at dose level three. No treatment-related deaths occurred, and the maximum tolerated dose was not reached. Three (25%) of 12 evaluable patients with relapsed or refractory acute myeloid leukaemia or myelodysplastic syndromes had an objective response. Among responders, two patients with acute myeloid leukaemia proceeded to allogeneic haematopoietic stem-cell transplantation (HSCT) after CYAD-01 treatment, with durable ongoing remissions (5 and 61 months). INTERPRETATION: Treatment with a multiple CYAD-01 infusion schedule without preconditioning is well tolerated and shows anti-leukaemic activity, although without durability outside of patients bridged to allogeneic HSCT. These phase 1 data support the proof-of-concept of targeting NKG2D ligands by CAR T-cell therapy. Further clinical studies with NKG2D-based CAR T-cells are warranted, potentially via combinatorial antigen targeted approaches, to improve anti-tumour activity. FUNDING: Celyad Oncology.

An 8-year pragmatic observation evaluation of the benefits of allogeneic HCT in older and medically infirm patients with AML.

We designed a prospective, observational study enrolling patients presenting for treatment of acute myeloid leukemia (AML) at 13 institutions to analyze associations between hematopoietic cell transplantation (HCT) and survival, quality of life (QOL), and function in: the entire cohort, those aged ≥65 years, those with high comorbidity burden, intermediate cytogenetic risk, adverse cytogenetic risk, and first complete remission with or without measurable residual disease. Patient were assessed 8 times over 2 years. Time-dependent regression models were used. Among 692 patients that were evaluable, 46% received HCT with a 2-year survival of 58%. In unadjusted models, HCT was associated with reduced risks of mortality most of the subgroups. However, after accounting for covariates associated with increased mortality (age, comorbidity burden, disease risks, frailty, impaired QOL, depression, and impaired function), the associations between HCT and longer survival disappeared in most subgroups. Although function, social life, performance status, and depressive symptoms were better for those selected for HCT, these health advantages were lost after receiving HCT. Recipients and nonrecipients of HCT similarly ranked and expected cure as main goal of therapy, whereas physicians had greater expectations for cure than the former. Accounting for health impairments negates survival benefits from HCT for AML, suggesting that the unadjusted observed benefit is mostly owing to selection of the healthier candidates. Considering patients' overall expectations of cure but also the QOL burdens of HCT motivate the need for randomized trials to identify the best candidates for HCT. This trial was registered at www.clinicaltrials.gov as #NCT01929408.

Outcomes in Patients with FLT3-Mutated Relapsed/ Refractory Acute Myelogenous Leukemia Who Underwent Transplantation in the Phase 3 ADMIRAL Trial of Gilteritinib versus Salvage Chemotherapy.

The fms-like tyrosine kinase 3 (FLT3) inhibitor gilteritinib improved the survival of patients with relapsed or refractory (R/R) FLT3-mutated acute myelogenous leukemia (AML) in the phase 3 ADMIRAL trial. In this study, we assessed survival and relapse rates of patients in the ADMIRAL trial who underwent hematopoietic stem cell transplantation (HSCT), as well as safety outcomes in patients who received post-transplantation gilteritinib maintenance therapy. ADMIRAL was a global phase 3 randomized controlled trial that enrolled adult patients with FLT3-mutated R/R AML. Patients with R/R AML who harbored FLT3 internal tandem duplication mutations in the juxtamembrane domain or D835/I836 point mutations in the tyrosine kinase domain were randomized (2:1) to gilteritinib (120 mg/day) or to preselected high- or low-intensity salvage chemotherapy (1 or 2 cycles). Patients in the gilteritinib arm who proceeded to HSCT could receive post-transplantation gilteritinib maintenance therapy if they were within 30 to 90 days post-transplantation and had achieved composite complete remission (CRc) with successful engraftment and no post-transplantation complications. Adverse events (AEs) during HSCT were recorded in the gilteritinib arm only. Survival outcomes and the cumulative incidence of relapse were assessed in patients who underwent HSCT during the trial. Treatment-emergent AEs were evaluated in patients who restarted gilteritinib as post-transplantation maintenance therapy. Patients in the gilteritinib arm underwent HSCT more frequently than those in the chemotherapy arm (26% [n = 64] versus 15% [n = 19]). For all transplantation recipients, 12- and 24-month overall survival (OS) rates were 68% and 47%, respectively. Despite a trend toward longer OS after pretransplantation CRc, post-transplantation survival was comparable in the 2 arms. Patients who resumed gilteritinib after HSCT had a low relapse rate after pretransplantation CRc (20%) or CR (0%). The most common AEs observed with post-transplantation gilteritinib therapy were increased alanine aminotransferase level (45%), pyrexia (43%), and diarrhea (40%); grade ≥3 AEs were related primarily to myelosuppression. The incidences of grade ≥III acute graft-versus-host disease and related mortality were low. Post-transplantation survival was similar across the 2 study arms in the ADMIRAL trial, but higher remission rates with gilteritinib facilitated receipt of HSCT. Gilteritinib as post-transplantation maintenance therapy had a stable safety and tolerability profile and was associated with low relapse rates. Taken together, these data support a preference for bridging therapy with gilteritinib over chemotherapy in transplantation-eligible patients.

Olutasidenib alone or with azacitidine in IDH1-mutated acute myeloid leukaemia and myelodysplastic syndrome: phase 1 results of a phase 1/2 trial.

BACKGROUND: Olutasidenib (FT-2102) is a potent, selective, oral, small-molecule inhibitor of mutant isocitrate dehydrogenase 1 (IDH1). The aims for phase 1 of this phase 1/2 study were to assess the safety, pharmacokinetics, pharmacodynamics, and clinical activity of olutasidenib, as monotherapy or in combination with azacitidine, in patients with acute myeloid leukaemia or myelodysplastic syndrome, harbouring mutant IDH1. METHODS: In this phase 1/2, multicentre, open-label clinical trial, we enrolled patients aged 18 years or older with acute myeloid leukaemia or intermediate, high, or very high risk myelodysplastic syndrome harbouring mutant IDH1 at 18 study sites in the USA, Australia, France, and Spain. Other key eligibility criteria included Eastern Cooperative Oncology Group performance status 0-2 with adequate liver and renal function. The primary outcomes were dose-limiting toxicities and the maximum tolerated dose, maximum evaluated dose, and the recommended phase 2 dose of olutasidenib. Olutasidenib was administered orally in doses of 150 mg once daily, 150 mg twice per day, and 300 mg once daily. Azacitidine (75 mg/m2) was administered subcutaneously or intravenously daily for 7 days on, 21 days off. The study was ongoing at the data cutoff (Oct 2, 2019) and is registered with ClinicalTrials.gov, NCT02719574. FINDINGS: Patients were enrolled between Aug 8, 2016, and Nov 14, 2018. 78 patients received olutasidenib as monotherapy (n=32) or in combination with azacitidine (n=46). The median follow-up was 8·3 months (IQR 3·1-13·3) for monotherapy and 10·1 months (4·2-15·3) for combination therapy. 16 (50%) of 32 patients in the monotherapy group and 24 (52%) of 46 patients in the combination therapy group were women. Most patients were White (26 [81%] for monotherapy and 31 [67%] for combination therapy). No dose-limiting toxicities were reported in the dose-escalation cohorts and 150 mg twice per day was declared the recommended phase 2 dose on the basis of safety, pharmacokinetics and pharmacodynamics, and clinical activity. The most common (≥20%) grade 3-4 treatment-emergent adverse events with monotherapy were thrombocytopenia (nine [28%] of 32 patients), febrile neutropenia (seven [22%] of 32), and anaemia (seven [22%] of 32); and with combination therapy were thrombocytopenia (19 [41%] of 46), febrile neutropenia (13 [28%] of 46), neutropenia (13 [28%] of 46), and anaemia (nine [20%] of 46). 11 (34%) of 32 patients in the monotherapy group and nine (20%) of 46 patients in the combination therapy group died (most commonly from disease progression [three (9%) of 32 and four (9%) of 46]). No deaths were considered study-drug related. For patients with relapsed or refractory acute myeloid leukaemia, 41% (95% CI 21-64; nine of 22) receiving monotherapy and 46% (27-67; 12 of 26) receiving combination therapy had an overall response. For treatment-naive patients with acute myeloid leukaemia, 25% (1-81; one of four) receiving monotherapy and 77% (46-95; ten of 13) receiving combination therapy had an overall response. INTERPRETATION: Olutasidenib, with or without azacitidine, was well tolerated and showed meaningful clinical activity in patients with IDH1-mutated acute myeloid leukaemia. The results of this phase 1 study provide rationale for the continued evaluation of olutasidenib in multiple patient populations with myeloid malignancies. FUNDING: Forma Therapeutics.

Phase 3 trial of gilteritinib plus azacitidine vs azacitidine for newly diagnosed FLT3mut+ AML ineligible for intensive chemotherapy.

Treatment results for patients with newly diagnosed FMS-like tyrosine kinase 3 (FLT3)-mutated (FLT3mut+) acute myeloid leukemia (AML) ineligible for intensive chemotherapy are disappointing. This multicenter, open-label, phase 3 trial randomized (2:1) untreated adults with FLT3mut+ AML ineligible for intensive induction chemotherapy to receive gilteritinib (120 mg/d orally) and azacitidine (GIL + AZA) or azacitidine (AZA) alone. The primary end point was overall survival (OS). At the interim analysis (August 26, 2020), a total of 123 patients were randomized to treatment (GIL + AZA, n = 74; AZA, n = 49). Subsequent AML therapy, including FLT3 inhibitors, was received by 20.3% (GIL + AZA) and 44.9% (AZA) of patients. Median OS was 9.82 (GIL + AZA) and 8.87 (AZA) months (hazard ratio, 0.916; 95% CI, 0.529-1.585; P = .753). The study was closed based on the protocol-specified boundary for futility. Median event-free survival was 0.03 month in both arms. Event-free survival defined by using composite complete remission (CRc) was 4.53 months for GIL + AZA and 0.03 month for AZA (hazard ratio, 0.686; 95% CI, 0.433-1.087; P = .156). CRc rates were 58.1% (GIL + AZA) and 26.5% (AZA) (difference, 31.4%; 95% CI, 13.1-49.7; P < .001). Adverse event (AE) rates were similar for GIL + AZA (100%) and AZA (95.7%); grade ≥3 AEs were 95.9% and 89.4%, respectively. Common AEs with GIL + AZA included pyrexia (47.9%) and diarrhea (38.4%). Gilteritinib steady-state trough concentrations did not differ between GIL + AZA and gilteritinib. GIL + AZA resulted in significantly higher CRc rates, although similar OS compared with AZA. Results support the safety/tolerability and clinical activity of upfront therapy with GIL + AZA in older/unfit patients with FLT3mut+ AML. This trial was registered at www.clinicaltrials.gov as #NCT02752035.

Small molecule MMRi62 targets MDM4 for degradation and induces leukemic cell apoptosis regardless of p53 status.

MDM2 and MDM4 proteins are key negative regulators of tumor suppressor p53. MDM2 and MDM4 interact via their RING domains and form a heterodimer polyubiquitin E3 ligase essential for p53 degradation. MDM4 also forms heterodimer E3 ligases with MDM2 isoforms that lack p53-binding domains, which regulate p53 and MDM4 stability. We are working to identify small-molecule inhibitors targeting the RING domain of MDM2-MDM4 (MMRi) that can inactivate the total oncogenic activity of MDM2-MDM4 heterodimers. Here, we describe the identification and characterization of MMRi62 as an MDM4-degrader and apoptosis inducer in leukemia cells. Biochemically, in our experiments, MMRi62 bound to preformed RING domain heterodimers altered the substrate preference toward MDM4 ubiquitination and promoted MDM2-dependent MDM4 degradation in cells. This MDM4-degrader activity of MMRi62 was found to be associated with potent apoptosis induction in leukemia cells. Interestingly, MMRi62 effectively induced apoptosis in p53 mutant, multidrug-resistant leukemia cells and patient samples in addition to p53 wild-type cells. In contrast, MMRi67 as a RING heterodimer disruptor and an enzymatic inhibitor of the MDM2-MDM4 E3 complex lacked MDM4-degrader activity and failed to induce apoptosis in these cells. In summary, this study identifies MMRi62 as a novel MDM2-MDM4-targeting agent and suggests that small molecules capable of promoting MDM4 degradation may be a viable new approach to killing leukemia cells bearing non-functional p53 by apoptosis.