Inhibition of MET Signaling with Ficlatuzumab in Combination with Chemotherapy in Refractory AML: Clinical Outcomes and High-Dimensional Analysis

Abstract

Acute myeloid leukemia (AML) patients refractory to induction therapy or relapsed within 1 year have poor outcomes. Autocrine production of hepatocyte growth factor by myeloid blasts drives leukemogenesis in preclinical models. A phase Ib trial evaluated ficlatuzumab, a first-in-class anti-HGF antibody, in combination with cytarabine in this high-risk population. Dose-limiting toxicities were not observed, and 20 mg/kg was established as the recommended phase II dose. The most frequent treatment-related adverse event was febrile neutropenia. Among 17 evaluable patients, the overall response rate was 53%, all complete remissions. Phospho-proteomic mass cytometry showed potent on-target suppression of p-MET after ficlatuzumab treatment and that attenuation of p-S6 was associated with clinical response. Multiplexed single-cell RNA sequencing using prospectively acquired patient specimens identified IFN response genes as adverse predictive factors. The ficlatuzumab and cytarabine combination is well tolerated, with favorable efficacy. High-dimensional analyses at single-cell resolution represent promising approaches for identifying biomarkers of response and mechanisms of resistance in prospective clinical studies. Significance: This study demonstrates a favorable safety profile and promising clinical activity of ficlatuzumab and cytarabine in high-risk AML, thus supporting further investigation of this combination in a randomized trial. It also shows the utility of a novel application using multiplexed single-cell analyses to detect on-target activity and identify biomarkers of response. This article is highlighted in the In This Issue feature, p. 403