A Phase 2 Study Examining AGEN2034 as a Single-Agent and in Combination With AGEN1884 in Patients With Recurrent, Inoperable Angiosarcoma

This Phase 2, open-label study is designed to examine the efficacy and safety of single-agent AGEN2034 and combination AGEN2034 + AGEN1884 in patients with recurrent, inoperable or metastatic AS.

Three cohorts will be enrolled into 2 Parts of the study as follows:

Part 1

• Cohort 1: Qualifying patients that are checkpoint inhibitor naïve will be enrolled into single-agent AGEN2034
• Cohort 2: Qualifying patients that are inhibitor (PD-1/L1) resistant will be enrolled into combination AGEN2034 + AGEN1884

Part 2

• Cohort 3: Qualifying patients that are checkpoint inhibitor naïve will be enrolled into combination AGEN2034 + AGEN1884. Part 2 will begin enrollment after enrollment in Part 1 is completed

The study will be conducted in 2 parts:

In Part 1, checkpoint inhibitor naïve patients will be treated with single-agent AGEN2034 (Cohort 1) and patients resistant to PD-1/PD-L1 (defined as prior progression on PD 1/PD-L1 treatment) will be treated with combination of AGEN2034+AGEN1884 (Cohort 2). Patients from Cohort 1 who experience PD may be considered (as PD-1 resistant) for transition to Cohort 2.

In Part 2, the study will enroll checkpoint inhibitor naïve patients for treatment with combination AGEN2034+AGEN1884 (Cohort 3). Part 2 will begin enrollment after enrollment in Part 1 is completed.

All patients will receive study treatment for up to 2 years until confirmed disease progression, unacceptable toxicity, or until the patient wishes to withdraw consent for any reason. Patients will be followed for safety at 30 and 90 days, and for survival every 2 months for at least 12 months from their last dose of study treatment. Each treatment cycle will be 6 weeks.

An IRC will be established to adjudicate tumor response based on imaging studies, photography, and clinical response. The primary endpoints will be based on the IRC assessment of response per RECIST v1.1.