A Phase 3, Randomized, Double-Blind, Placebo-Controlled Study to Assess the Efficacy and Safety of Entospletinib in Combination with Intensive Induction and Consolidation Chemotherapy in Adults with Newly Diagnosed Nucleophosmin 1-mutated Acute Myeloid Leukemia

Background: Spleen tyrosine kinase (SYK) is a component of both lymphoid and myeloid cell signaling pathways and has been implicated in the pathogenesis of a subset of acute myeloid leukemia (AML) defined by dysregulated expression of the HOXA9 and MEIS1 transcription factors. Entospletinib (ENTO) is an oral, selective SYK inhibitor that is acceptably tolerated when administered with intensive induction and consolidation in newly diagnosed AML patients. In a phase 2 study, following induction with cytarabine and daunorubicin (7+3) plus ENTO, higher rates of complete response (CR) or CR with incomplete hematologic recovery (CRi) were observed in patients with rearrangements of the KMT2A (MLL) gene (MLL-r) and mutations of the nucleophosmin 1 (NPM1) gene, both of which are associated with aberrant expression of HOXA9 and MEIS1, as compared to patients without these mutations. In an exploratory analysis, patients with HOXA9/MEIS1 expression levels above the median experienced superior overall survival (OS) as compared to patients with expression levels below the median. In the AGILITY trial, we hypothesize that the addition of ENTO to intensive induction/consolidation in newly diagnosed patients with NPM1-mutated AML will improve the rate of CR without evidence of measurable residual disease (MRD-negative CR) post-induction and duration of event-free survival (EFS).

Methods: AGILITY will be a global, multi-center, double-blind, placebo-controlled trial of ENTO in combination with cytarabine plus daunorubicin or idarubicin induction (7+3) and age-adjusted high-dose cytarabine (HiDAC) consolidation in newly diagnosed AML patients aged 18-75 years who are candidates for intensive induction and harbor a documented NPM1 mutation based on local or central mutation testing. Patients with co-mutated FLT3 (internal tandem duplication or tyrosine kinase domain) and for whom midostaurin with 7+3 is indicated are excluded. Patients will be stratified based on age (<60 vs ≥60 years) and anthracycline administered during induction (daunorubicin vs idarubicin). Approximately 180 patients will be randomized to receive 7+3 induction and HiDAC consolidation with ENTO (400 mg orally twice daily) versus 7+3 induction and HiDAC with placebo. Patients with <5% leukemic blasts after 1 cycle of induction will proceed to the first cycle of HiDAC consolidation while patients with ≥5% residual blasts will undergo a second induction cycle. Patients who do not achieve CR after 2 cycles of chemotherapy (either 2 induction cycles or 1 induction and 1 consolidation cycle) plus ENTO or placebo will be designated as induction treatment failures (ITF). Patients who achieve or remain in CR after 2 chemotherapy cycles will be evaluated for MRD in bone marrow based on enumeration of mutant NPM1 alleles using a molecular assay. Patients may receive up to 3 cycles of consolidation with HiDAC and ENTO or placebo beyond chemotherapy cycle 2 per their original randomized treatment assignment. The number of consolidation cycles and timing of hematopoietic stem cell transplant (HSCT) or other post-consolidation therapy (if any) is at the discretion of the investigator. All patients will be followed for relapse and survival. The primary endpoint will be the rate of MRD-negative CR (<0.01% mutant NPM1 alleles). Patients without an evaluation of response and MRD after chemotherapy cycle 2 will be imputed as treatment failures for the analysis. A key secondary endpoint will be EFS, defined as time from randomization to the earliest occurrence of ITF, relapse from CR, or death from any cause. Patients without an event at the time of the EFS analysis will be censored at the last study evaluation they were event-free. EFS will be estimated using the Kaplan-Meier method and summarized by treatment group. Differences between treatment groups will be assessed with the log-rank test stratified by age (<60 vs ≥60 years) and choice of anthracycline in induction (daunorubicin vs idarubicin). OS will be analyzed in a similar manner. Key exploratory endpoints will be the correlation between recurring genomic mutations and response or progression and longitudinal assessment of peripheral blood for detection of NPM1-m alleles among patients who achieve MRD-negative CR post-induction.

An independent data-monitoring committee will monitor emerging safety and efficacy data from this trial on an ongoing basis.