Phase I Pilot Study of RRx-001 + Nivolumab in Patients with Traditionally Non-Checkpoint Inhibitor-Responsive Cancers (PRIMETIME).

e15119 Background: RRx-001 is a minimally toxic small molecule that downregulates CD47 via Myc inhibition and repolarizes tumor-associated macrophages (TAMs). A phase 1 pilot study was undertaken to determine the safety and feasibility of RRx-001 and nivolumab in patients with advanced traditionally non-immunogenic cancers and no standard options. Methods: This single arm, open-label pilot study (NCT02518958) was designed to evaluate the safety profile of RRx-001 + nivolumab in patients with advanced malignancies. A 3+3 trial design was used to establish safety of the combination at each dose level and guide the decision to escalate dose. RRx-001 is infused once weekly while nivolumab is given at 3mg/kg once every 2 weeks. RRx-001 starting dose was 2 mg IV weekly with 4 dose level escalations up to 16 mg IV weekly. From January 2015 to November 2015, 12 patients received treatment for 4 cycles (total 12 weeks) with the combination due to unavailability of nivolumab, which was not supplied to the Sponsor. Treatment-emergent (all cause, TEAEs) and treatment-related (TRAEs) adverse events occurring within 16 weeks of the first dose of RRx-001 + nivolumab were characterized according to CTCAE v4.03. Results: 12 patients received > 1 dose of RRx-001 and nivolumab. One discontinuation occurred due to pneumonitis and one to voluntary withdrawal after a post-procedural infection. There were no dose-limiting toxicities. The main adverse event related to RRx-001 was pain on infusion (33.3%). The main adverse event related to the combination was pseudoprogression (larger tumors in symptomatically improved patients) (25%). The most common immune-related treatment-emergent AEs were pneumonitis (8.3%), and hypothyroidism (8.3%). Objective response rate at 12 weeks was 25% and the disease control rate (DCR) consisting of > SD was 67% by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. 25% of the patients progressed on the combination. Conclusions: RRx-001 + nivolumab was well-tolerated with preliminary evidence of anti-cancer activity in non-immunogenic cancers. Further analyses with a larger sample size are required to confirm activity. Clinical trial information: NCT02518958 .