Initial results of a phase I study of MK-4830, a first-in-class anti–immunoglobulin-like transcript 4 (ILT4) myeloid-specific antibody in patients (pts) with advanced solid tumours

Document Type

Conference Proceeding

Publication Date

9-2020

Publication Title

Annals of Oncology

Abstract

Background: MK-4830 is a novel, first-in-class human IgG4 monoclonal antibody targeting the myeloid-specific ILT4 receptor. MK-4830 catalyzes reprogramming of tumour-associated macrophages, relieving myelosuppression and enhancing T cell function. We present data from the first-in-human phase I dose escalation study (NCT03564691) of MK-4830 and MK-4830 + pembrolizumab (pembro). Methods: Pts with advanced solid tumours received MK-4830 IV Q3W at escalating doses alone and with pembro. Primary end points were safety and tolerability. PK was a secondary end point; exploratory objectives included ORR per RECIST v1.1, evaluation of receptor occupancy (RO), and immune correlates of response in blood and tumour. Results: Among 84 pts, 50 received MK-4830 monotherapy; 34 received MK-4830 + pembro. Median age was 62 years; 50% previously received ≥3 lines of therapy. No dose-limiting toxicities were observed; maximum-tolerated dose was not reached. Any-grade AEs were consistent with those common to pembro. Treatment-related AEs were reported in 52% of pts; most were grade 1/2. MK-4830 steady-state serum PK at Ctrough was achieved at the highest dose levels, at which almost all pts had ≥95% blood RO. Preliminary efficacy data show 11 objective responses, with 2 complete responses and 9 partial responses; 1 response was observed in a patient receiving MK-4830 monotherapy. All responses occurred in heavily pretreated pts, 5 of whom had not had a response to prior anti–PD-1 therapy. Responses were durable; some pts received >1 year of treatment. Pre- and on-treatment (n=15) biopsies enabled a preliminary assessment of correlation between RO and immune cell subsets before and during treatment. Conclusions: This first-in-class MK-4830 antibody targeting ILT4 given as monotherapy and in combination with pembro was well tolerated and showed dose-related evidence of target engagement. Durable responses were observed with both MK-4830 alone and with MK-4830 + pembro in heavily pretreated pts, 5 of whom progressed on prior anti–PD-1 therapies. These initial data support the further development of MK-4830 + pembro for pts with advanced solid tumors. Clinical trial identification: NCT03564691.

Volume

31

First Page

S462

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