Background: Metastatic pancreatic ductal adenocarcinoma (mPDAC) remains a challenging cancer to treat, with median survival of <1 year. In PDAC, extracellular adenosine (eADO) produced from ATP is released from tumor cells and suppresses antitumor immune responses. Quemliclustat (Q) is a potent and selective small-molecule inhibitor of soluble and cell-bound CD73, a key enzyme involved in the production of eADO within the tumor microenvironment. Elevated CD73 expression is found in 40-60% of PDAC and correlates with poor clinical outcome. ARC-8 evaluated Q ± anti-PD-1 antibody zimberelimab (Z) in combination with gemcitabine/nab-paclitaxel (G/nP). Methods: ARC-8 (NCT04104672) is a phase 1b dose escalation and expansion study in patients (pts) with treatment-naive mPDAC. Q 100mg was previously determined as the recommended dose for expansion (Manji et al., 2021). Q 100 mg is administered with standard doses of G/nP with Z (240 mg IV Q2W) in the dose expansion (Cohort A; QZ+G/nP) and in randomized (2:1) cohorts either with Z (Cohort A1; QZ+G/nP) or without Z (Cohort A2; Q+G/nP). Adverse events (AEs) are recorded and graded per NCI CTCAE 5.0. Clinical activity is assessed every 8 weeks per RECIST v1.1. Endpoints include measures of safety and median overall survival (OS). Results: As of June 19, 2023, 122 patients with untreated mPDAC were treated with Q 100mg, including 93 pts treated with QZ+G/nP (dose escalation, n=6; cohort A, n=26; and randomized cohort A1, n=61) and 29 pts treated with Q+G/nP (Cohort A2). Median age was 66 years, 66% ECOG of 1, and 65% had liver metastasis at baseline. Median survival follow-up was 21 months (mos). Efficacy is summarized in Table 1. All patients reported AE, 85% Grade 3+ AE, and 23% discontinued study treatment due to AE. Most common Grade 3+ AE was neutrophil count decreased (31%) and anemia (25%). Conclusions: Results from ARC-8 demonstrate the addition of Q 100 mg ± Z to G/nP was safe and tolerable, with no significant added toxicity to GnP. Modulation of eADO with Q may confer benefit beyond radiographic measures of disease. The OS is promising and supports further development of Q in mPDAC. Clinical trial information: NCT04104672.

Reference: Manji G, et al. ASCO GI 2021. Abstract 404.