Preoperative (neoadjuvant) therapy with tislelizumab for locally advanced colorectal cancer with high microsatellite instability or deficient mismatch repair: An open-label, single-arm, multicenter phase II study.

• DOI: 10.1200/jco.2024.42.16_suppl.3599
• Publication Date: 2024-06-17T14:13:05Z
• Authors: Ke-Feng Ding; Gong Chen; Yao Ye; Yue Liu; Yanlai Sun; Yang Gao; Jingdong Zhang; Shaozhong Wei; Cong Li; Dandan Li; Yanbing Zhou; Mulin Liu; Juan Zhang; Lilin Zhang; Dalu Kong
• Keywords: Microsatellite Instability; Open label

3599 Background: Tislelizumab (TIS), an anti-programmed cell death protein 1 (PD-1) antibody, demonstrated improved anti-tumor response and tolerable safety in patients (pts) with previously treated, locally advanced unresectable or metastatic microsatellite instability high/deficient mismatch repair (MSI-H/dMMR) solid tumors, including colorectal cancer (CRC; NCT03736889). Recent studies of other anti-PD-1 antibodies indicate potential clinical benefit neoadjuvant therapy pts resectable MSI-H/dMMR CRC. Here, we report efficacy outcomes TIS from a multicenter phase II trial (NCT05116085) this population. Methods: Pts aged ≥18 years stage II/III CRC, ECOG PS 0-1, evaluable disease per RECIST v1.1, eligible for R0 (complete) resection were enrolled. received 200 mg IV every 3 weeks cycles followed by surgical within 10 first dose. The primary endpoint was major pathological (MPR) rate (proportion ≤10% residual viable tumor the surgically resected tumor). Secondary endpoints included complete (pCR) absence specimen), safety. exploratory endpoint. Results: Overall, 33 enrolled across eight sites China. median age 52.0 (range: 23-84), 14 (42.4%) male. Ten (30.3%) had rectal 23 (69.7%) colon cancer. At study entry, (T) reported as T2, T3, T4 (3.0%), 7 (21.2%), 25 (75.8%) pts, respectively, node (N) N0, N1, N2 6 (18.2%), (42.4%), 13 (39.4%) respectively. All metastasis (M) M0. A total 29 (87.9%) underwent surgery endpoints. Surgery not performed 4 whom managed non-operatively (1 pt progressive disease). MPR pCR rates 89.7% 62.1%, respectively (Table). Any-grade grade ≥3 TIS-related adverse events (TRAEs) 20 (60.6%) (3.0%) Two (6.1%) experienced serious TRAEs; no TRAEs led to cancellation. One TRAE (grade 2 hypothyroidism) leading delay. No surgery-relevant reported. Immune-mediated (all 1-2). Conclusions: Neoadjuvant associated high acceptable profile, did compromise Clinical information: NCT05116085 . [Table: see text]