Neoadjuvant anti-programmed death 1 (PD-1) therapy in patients (pts) with resectable mismatch repair–deficient (dMMR) locally advanced rectal cancer (LARC): EPOC2201.

Abstract

TPS226 Background: Neoadjuvant radiotherapy and chemotherapy followed by surgical resection is a standard treatment for LARC. As anti-PD-1 therapy for patients with dMMR colorectal cancer is responsive in the context of metastatic disease, several clinical trials which evaluate the efficacies of anti-PD-1 therapy in patients with dMMR LARC are on-going and suggested the outstanding responses (Cercek A. et al., N Engl J Med 2022). Methods: We initiated the EPOC 2201 VOLTAGE-2 study, which is an ongoing, non-randomized, single-arm phase II trial. The major eligibility criteria were as follows: treatment-naïve with rectal cancer located 12 cm from the anal verge; confirmed dMMR; clinical stage II/III in primary cohort (N=35) and stage I in exploratory cohort (N=20); age ≥ 18; Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1; and presence of sufficient organ function. The study treatments include 12 cycles of nivolumab (NIVO) monotherapy (240 mg every 2 weeks) followed by assessment using Memorial Sloan Kettering (MSKCC) Regression Schema (Smith J.J. et al., BMC Cancer 2015). If clinical complete response (cCR) or near complete response (nCR) are observed, non-operative management with additional 12 cycles of NIVO will be performed. If incomplete response (IR) is observed, standard chemoradiotherapy with 50.4Gy of radiation plus capecitabine followed by surgery will be performed. The primary endpoint is the 2-year cCR rate in primary cohort. Various survival endpoints including progression-free survival (PFS) and overall survival (OS) are assessed as secondary endpoints. Safety analyses are performed using the Common Terminology Criteria for Adverse Events (CTCAE) ver. 5.0, and the Clavien‒Dindo classification (ver. 2.0) is added for postoperative complications. Assuming null and alternative hypotheses, cCR rates of 23% and 45%, the planned sample size for primary cohort was set at 35, with a one-sided alpha of 5% and power of 80%. An exploratory biomarker study was also conducted using serially collected tumor and blood samples. Whole genome-based minimal residual disease (MRD) assay and whole exome/whole transcriptome-based tumor and immune microenvironment analyses are performed. As of August 2023, patient’s enrollment is ongoing. Clinical trial information: jRCT2031220484 .