Background: Microsatellite-stable (MSS) colorectal cancer (CRC) tends to be poorly immunogenic, with limited treatment options. In MSS CRC xenograft models, trifluridine/tipiracil (FTD/TPI) plus programed death 1 inhibitors resulted in synergistic antitumor activity and increased tumor immunogenicity. This phase 2 study evaluated FTD/TPI plus nivolumab in patients with MSS metastatic CRC.
Methods: This single-arm, safety lead-in study used a Simon's two-stage design (enrolling 6 patients in the safety lead-in, proceeding to stage 2 if ≥2 of the first 15 patients achieved a partial or complete response per immune-related response criteria [irRC] within 6 months). Patients with histologically proven MSS mCRC, and disease progression after ≥2 prior chemotherapy regimens received FTD/TPI (35 mg/m2 twice daily; days 1-5 and 8-12 every 28 days) plus nivolumab (3 mg/kg every 2 weeks).
Results: Between August 2016 and January 2017, 18 patients (50% men; median age 56.5 years) were enrolled; 72% had colon cancer and 56% had KRAS mutations. All patients received treatment (median, 2.5 cycles [range, 1-8]). No dose-limiting toxicities were observed in the study. The most frequent adverse events (AEs) of any cause and grade were nausea (67%), diarrhea (61%), and neutropenia (50%); 13 patients (72%) experienced grade ≥3 AEs. No patients discontinued treatment because of AEs. No patient achieved a tumor response (either per Response Evaluation Criteria in Solid Tumors [RECIST] or irRC), and the study did not progress to the second stage. Stable disease was achieved in 8 patients per irRC and in 10 patients per RECIST. Median progression-free survival was 2.2 months (95% CI, 1.8-6.0 months) per irRC and 2.8 months (95% CI, 1.8-5.1 months) per RECIST.
Conclusion: Patients with refractory MSS metastatic CRC failed to experience clinical benefit with FTD/TPI plus nivolumab, although safety data in this population indicated tolerability and feasibility of this combination.
Trial registration number: NCT02860546.
Keywords: chemotherapy; clinical trials; colorectal cancer; immunotherapy.
© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.