A phase I dose escalation study evaluating the safety and tolerability of a novel anti-HER2 antibody-drug conjugate (PF-06804103) in patients with HER2-positive solid tumors.
Funda Meric‐Bernstam, Emiliano Calvo, Víctor Moreno, Hyun Cheol Chung, Yeon Hee Park, Yung‐Jue Bang, Lee S. Rosen, Monica Mita, Ignacio Garrido‐Laguna, Abraham C.F. Leung, Harman Dube, Wei Zhong, Xiaoying Chen, Rula Dawaher, Giuseppe Curigliano
Abstract
1039 Background: PF-06804103 is an anti-HER2 immunoglobulin G1 antibody-drug conjugate (ADC), comprising an anti-HER2 monoclonal antibody conjugated with a cleavable linker to the cytotoxic agent Aur0101. PF-06804103 demonstrated strong activity in low to high HER2-expressing preclinical tumor models. In this study, the safety and tolerability of PF-06804103 was assessed in patients with advanced breast cancer (BC) or gastric cancer (GC). Methods: This multi-center, open-label, first-in-patient, phase I study (NCT03284723) has two parts: dose escalation (Part 1) and dose expansion (Part 2). In Part 1, groups of adult patients (pts) with HER2+ BC or HER2+ GC, who are resistant or intolerant to standard therapy or for which no standard therapy is available, received PF-06804103 intravenously once every 21 days (Q3W); dosage was escalated per cohort. Primary objectives were to evaluate the safety and tolerability of PF-06804103, characterize its dose-limiting toxicities (DLTs), and determine the recommended phase 2 dose. Response was assessed using RECIST v1.1. Objective response rate (ORR) was calculated for response-evaluable pts with target lesions at baseline and ≥1 post-baseline assessment (including unconfirmed responses). Results: A total of 35 pts (BC: n = 20; GC: n = 15) received PF-06804103 at escalating dose levels (0.15 mg/kg: n = 2; 0.5 mg/kg: n = 2; 1.2 mg/kg: n = 2; 2 mg/kg: n = 4; 3 mg/kg: n = 10; 4 mg/kg: n = 9; 5 mg/kg: n = 6). The median (range) number of prior therapies was 6 (3–18) and 3 (1–6) for BC and GC groups, respectively (all pts had prior HER2-targeted therapy). The 3 most common, drug-related adverse events (any grade) were alopecia (n = 17, 48.6%), fatigue (n = 15, 42.9%), and neuropathy (n = 9, 25.7%). DLTs (mostly grade 3) occurred in 3 pts and included arthralgia, neuropathy, myalgia, fatigue, and osteomuscular pain. Preliminary ORR in the patients treated with doses ≥3mg/kg was 52.4% (11/21). Conclusions: The PF-06804103 ADC demonstrated manageable toxicity and promising anti-tumor activity in this small, heavily pretreated study population. Clinical trial information: NCT03284723 .