Phase 1 open-label, multiple ascending dose trial of AGEN1884, an anti-CTLA-4 monoclonal antibody, in advanced solid malignancies.

Abstract

3075 Background: AGEN1884 is a fully human IgG1 monoclonal antibody targeting the co-inhibitory protein cytotoxic T lymphocyte-associated protein 4 (CTLA-4). CTLA-4 blockade has been shown to augment T cell activation and proliferation, resulting in immune infiltration of the tumor and subsequent regression. Objectives: Assess the safety, maximum tolerated dose (MTD), and pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of AGEN1884 in patients (pts) with advanced and refractory malignancies using a “3+3” trial design. Methods: Eleven pts have been enrolled and treated to date. AGEN1884 was administered intravenously q3w for 4 doses and then q12w. Three (0.1, 0.3 and 1 mg/kg) of six (3, 6 and 10 mg/kg) planned dose levels have been completed. Results: Five pts were accrued at 0.1 mg/kg dose level (2 were not DLT evaluable) and three pts each at doses of 0.3 mg/kg and 1 mg/kg. Median age was 56 years (range 26–70), ECOG 0–2, with a median of 4 (range 1–8) prior therapies. No DLT events have been observed thus far. Data from 5 pts were available for PK evaluation. Half-life of AGEN1884 post first dose was 8.8 and 9.6 days for 0.3 mg/kg and 0.1 mg/kg dose levels, respectively, as measured by ELISA. As of Jan 31, 2017, pts across cohorts were followed for a median of 6 weeks (range 0-28). Six pts (54.5%) have come off study due to disease progression, while 5 (45.5 %) remain on study. One confirmed partial response (80% reduction) by RECIST criteria was seen at 0.1 mg/kg in a patient with angiosarcoma. Conclusions: AGEN1884 is safe at 0.1 and 0.3 mg/kg dose levels. Dose escalation is ongoing and updated safety and PK data will be presented. Clinical trial information: NCT02694822.