Phase I study of REGN421 (R)/SAR153192, a fully-human delta-like ligand 4 (Dll4) monoclonal antibody (mAb), in patients with advanced solid tumors.

Abstract

2502 Background: Dll4, a Notch receptor ligand, may have a role in tumor angiogenesis and is an emerging anticancer target. REGN421 (R) is a fully human IgG 1 mAb that binds human Dll4 and disrupts Notch-mediated signaling. Methods: Primary objectives of the dose escalation (3+3 design) trial were to determine safety and a recommended phase II dose (RP2D) of R in patients (pts) with advanced cancer. R was given IV at doses of 0.25, 0.5, 1, 2 and 4mg/kg every 3 weeks (Q3W) or 0.75, 1, 1.5, and 3mg/kg every 2 weeks (Q2W). Secondary objectives were PK, immunogenicity, and antitumor activity. Results: 53 pts (M/F=22/31, ECOG 0/1=18/35) were enrolled; 31 pts were treated Q3W at doses of 0.25 - 4 mg/kg; 22 pts were treated Q2W at doses of 0.75 - 3 mg/kg. Two DLTs occurred: Grade 3 (Gr3) nausea (0.5mg/kg Q3W) and Gr3 abdominal pain (1 mg/kg Q2W). A maximum tolerated dose was not reached on either schedule. Grade 3/4 AEs occurred in 29 pts; nausea, abdominal pain, dyspnea, hypoxia, and hypertension (HTN) were reported in ≥ 5%. Most frequent treatment related AEs were fatigue (30%), headache (26%), HTN (26%), and nausea (15%). Six treatment related SAEs (all reversed off treatment) were reported in 4 patients: BNP increase (0.25mg/kg, Gr1), troponin I increase (4mg/kg, Gr3), right ventricular dysfunction (1.5mg/kg, Gr3), left ventricular dysfunction (3mg/kg, Gr3) and 2 events of pulmonary HTN (1.5mg/kg, Gr 3, and 3mg/kg Gr3). Laboratory abnormalities (≥ Gr3) were neutropenia (3) and anemia (2), and elevated ALP (7), ALT (3), bilirubin (3), AST (2), and decreased albumin (1). Anti-tumor activity included 2 PRs (NSCLC BAL-type with a beta-catenin mutation and ovarian cancer [OvCa]), and 16 pts with SD (3 pts had SD > 6 months). Two of 8 pts with OvCa had CA125 responses. R had non-linear target-mediated PK without accumulation. The half-life of R at 3mg/kg Q2W was 7 days. No immunogenicity was observed. Conclusions: REGN421 had an acceptable safety profile, and RP2Ds of 4mg/kg Q3W and 3mg/kg Q2W. Responses and prolonged SD were noted in OvCa pts and other solid tumors. Dose escalation has concluded and disease specific expansion cohorts are ongoing. Clinical trial information: NCT00871559.