First-in-human, phase I study of PF-06647263, an anti-EFNA4 calicheamicin antibody-drug conjugate, in patients with advanced solid tumors

Abstract

PF-06647263, a novel antibody-drug conjugate consisting of an anti-EFNA4 antibody linked to a calicheamicin payload, has shown potent antitumor activity in human xenograft tumor models, including triple-negative breast cancer (TNBC). In the dose-escalation part 1 of this multicenter, open-label, phase I study (NCT02078752), successive cohorts of patients (n, 48) with advanced solid tumors and no available standard therapy received PF-06647263 every 3 weeks (Q3W) or every week (QW), following a modified toxicity probability interval (mTPI) method (initial dosing: 0.015 mg/kg Q3W). Primary objective in part 1 was to estimate the maximum tolerated dose (MTD) and select the recommended phase 2 dose (RP2D). In part 2 (dose-expansion cohort), 12 patients with pretreated, metastatic TNBC received PF-06647263 at the RP2D to further evaluate tumor response and overall safety. PF-06647263 QW administration (n, 23) was better tolerated than the Q3W regimen (n, 25) with only 1 DLT reported (thrombocytopenia). The most common AEs with the QW regimen (fatigue, nausea, vomiting, mucosal inflammation, thrombocytopenia, and diarrhea) were mostly mild to moderate in severity. The MTD was not estimated. PF-06647263 exposures increased in a dose-related manner across the doses evaluated. The RP2D was determined to be 0.015 mg/kg QW. Six (10%) patients achieved a confirmed partial response and 22 (36.7%) patients had stable disease. No correlations were observed between tumor responses and EFNA4 expression levels. Study findings showed manageable safety and favorable PK for PF-06647263 administered QW at the RP2D, with preliminary evidence of limited antitumor activity in patients with TNBC and ovarian cancer.

Keywords: ADC; EFNA4; PF-06647263; calicheamicin; solid tumors.

Conflict of interest statement

Conflict of interest: This study was sponsored by Pfizer. I. Garrido-Laguna has disclosed no relevant conflicts of interest.

© 2019 UICC.

Figures

Figure 1.

Maximum percent change in tumor size for target lesions (a) in dose-escalation patients with solid tumors by dose level (n = 34), and (b) in dose-expansion patients with TNBC (n = 10). Only patients with both baseline and postbaseline tumor assessments were included, in this analysis. Dashed lines indicate a 30% decrease and a 20% increase from baseline in the sum of longest diameters for target lesions. PD: progressive disease; PR: partial response; Q3W: every 3 weeks; QW: every week; SD: stable disease; TNBC: triple-negative breast cancer; uPR: unconfirmed PR.