Spleen tyrosine kinase/FMS-like tyrosine kinase-3 inhibition in relapsed/refractory B-cell lymphoma, including diffuse large B-cell lymphoma: updated data with mivavotinib (TAK-659/CB-659).

We report an updated analysis from a phase I study of the spleen tyrosine kinase (SYK) and FMS-like tyrosine kinase 3 inhibitor mivavotinib, presenting data for the overall cohort of lymphoma patients, and the subgroup of patients with diffuse large B-cell lymphoma (DLBCL; including an expanded cohort not included in the initial report). Patients with relapsed/refractory lymphoma for which no standard treatment was available received mivavotinib 60-120 mg once daily in 28-day cycles until disease progression/unacceptable toxicity. A total of 124 patients with lymphoma, including 89 with DLBCL, were enrolled. Overall response rates (ORR) in response-evaluable patients were 45% (43/95) and 38% (26/69), respectively. Median duration of response was 28.1 months overall and not reached in DLBCL responders. In subgroups with DLBCL of germinal center B-cell (GCB) and non-GCB origin, ORR was 28% (11/40) and 58% (7/12), respectively. Median progression free survival was 2.0 and 1.6 months in the lymphoma and DLBCL cohorts, respectively. Grade ≥3 treatment-emergent adverse events occurred in 96% of all lymphoma patients, many of which were limited to asymptomatic laboratory abnormalities; the most common were increased amylase (29%), neutropenia (27%), and hypophosphatemia (26%). These findings support SYK as a potential therapeutic target for the treatment of patients with B-cell lymphomas, including DLBCL. Trial registration: ClinicalTrials.gov number: NCT02000934.

A phase Ib trial of mivavotinib (TAK-659), a dual SYK/FLT3 inhibitor, in patients with relapsed/refractory acute myeloid leukemia.

Mivavotinib (TAK-659) is an investigational type 1 tyrosine kinase inhibitor with dual activity against spleen tyrosine kinase (SYK) and FMS-like tyrosine kinase 3 (FLT3). We conducted a phase Ib study to investigate the safety, tolerability, and efficacy of mivavotinib in patients with refractory and/or relapsed (R/R) acute myeloid leukemia (AML). Both daily (QD) and twice daily (BID) dosing regimens were evaluated. A total of 43 patients were enrolled, and there were 5 complete responses (4 with incomplete count recovery). In the QD dosing regimen, the maximum tolerated dose (MTD) was not reached up to 160 mg QD per protocol; 140 mg QD was identified as the recommended phase II dose. In the BID dosing regimen, the MTD was 60 mg BID. Thirty patients (70%) experienced a bleeding event on study; the majority were grades 1 or 2, were resolved without mivavotinib modification, and were not considered related to study treatment. Eleven patients (26%) experienced grade ≥3 bleeding events, which were observed most frequently with the 80 mg BID dose. We conducted platelet aggregation studies to investigate the potential role of mivavotinib-mediated SYK inhibition on platelet function. The bleeding events observed may have been the result of several confounding factors, including AML disease status, associated thrombocytopenia, and high doses of mivavotinib. Overall, these findings indicate that the activity of mivavotinib in R/R AML is modest. Furthermore, any future clinical investigation of this agent should be undertaken with caution, particularly in thrombocytopenic patients, due to the potential bleeding risk of SYK inhibition. ClinicalTrials.gov: NCT02323113.

Phase I Study of TAK-659, an Investigational, Dual SYK/FLT3 Inhibitor, in Patients with B-Cell Lymphoma.

PURPOSE: TAK-659 is an investigational, dual SYK/FLT3 inhibitor with preclinical activity in B-cell malignancy models. This first-in-human, dose-escalation/expansion study aimed to determine the safety, tolerability, MTD/recommended phase II dose (RP2D), and preliminary efficacy of TAK-659 in relapsed/refractory solid tumors and B-cell lymphomas. PATIENTS AND METHODS: Patients received continuous, once-daily oral TAK-659, 60-120 mg in 28-day cycles, until disease progression or unacceptable toxicity. The study applied an accelerated dose-escalation design to determine the MTD and RP2D. In the expansion phase, patients with lymphoma were enrolled in five disease cohorts at the MTD. RESULTS: Overall, 105 patients were enrolled [dose escalation, n = 36 (solid tumors, n = 19; lymphoma, n = 17); expansion, n = 69]. The MTD was 100 mg once daily. TAK-659 absorption was fast (T max ∼2 hours) with a long terminal half-life (∼37 hours). Exposure generally increased with dose (60-120 mg), with moderate variability. The most common treatment-related adverse events were generally asymptomatic and reversible elevations in clinical laboratory values. Among 43 response-evaluable patients with diffuse large B-cell lymphoma, 8 (19%) achieved a complete response (CR) with an overall response rate (ORR) of 28% [23% intent-to-treat (ITT)]. Responses were seen in both de novo and transformed disease and appeared independent of cell-of-origin classification. Among 9 response-evaluable patients with follicular lymphoma, 2 (22%) achieved CR with an ORR of 89% (57% ITT). CONCLUSIONS: TAK-659 has single-agent activity in patients with B-cell lymphoma. Further studies of the drug in combination, including an evaluation of the biologically optimal and safest long-term dose and schedule, are warranted.