PD-1 blockade plus chemotherapy followed by concurrent SBRT with SIB as preoperative therapy for patients with potentially resectable pancreatic cancer: A single-arm phase 2 study.

e16312 Background: Pancreatic cancer has 10% low rate of early diagnosis and resection due to its insidious onset and poor prognosis. We aimed to assess the safety and efficacy of a new mode of preoperative therapy for patients with Potentially Resectable Pancreatic Cancer. Methods: This is a single arm clinical trial (NCT05634564). Gemcitabine (1000 mg/m2) and nabpaclitaxel (125 mg/m2; AG) were administered to patients with LAPC or BRPC on days 1 and 8, along with tislelizumab (200 mg) on day 1 intravenously (IV) every three weeks. Concurrently, the patients underwent stereotactic body radiotherapy (SBRT) with simultaneous integrated boost (SIB)during the third cycle of treatment. Surgical intervention was reassessed after four cycles of treatment. Objective response rate (ORR) was the primary endpoint and Disease control rate (DCR), R0 resection rate, median overall survival (mOS), median progression free survival (mPFS) rate, time to progression (TTP) and safety were analyzed as secondary endpoints. Results: Between May 2020 and April 2023, 62 patients with LAPC or BRPC were enrolled. Until the last follow-up time (January 30, 2024) ,56 of them included in the intention-to-treat (ITT) analysis who completed at least three cycles of tislelizumab plus AG and underwent concurrent radiotherapy. The median age in intention-to-treat analysis was 65 years. 25 patients had a best response of partial response, the ORR was 44.6%, DCR was 100%. Thirty-one patients met the criteria for surgical resection after treatment, 9 of whom refused surgery and continued conservative treatment. 22 patients underwent resection, and the R0 resection rate was 95.45%. Two of the 22 resected patients achieved pathologic complete response (pCR) and five patients achieved major pathological response (MPR). The pathologic complete response rate was 9.10% and significant pathological response rate was 31.82%. The TTP was 19.38 months (95% CI: 12.8%-27.9%), and the mOS was 21.32 months (95% CI:15.9%-NR). The 12-months PFS rate and 12-months OS rate were 59.9% (95% CI:45.2%-71.8%) and 74.4% (95% CI:59.9%-84.3%), respectively. Grade 5 adverse events were not observed. The most common grade 3-4 hematological and non-hematological toxicities were leukopenia (17.9%), neutropenia (16.1%), anemia (8.9%), thrombocytopenia (7.1%), rash: dermatitis (7.1%), Peripheral neuropathy (3.6%). Conclusions: Anti-PD-1 inhibitor tislelizumab plus AG chemotherapy followed by concurrent SBRT with SIB significantly prolonged mPFS rate, as well as R0 resection rate of surgical patients, and also improved the major pathological response rate. Clinical trial information: NCT05634564 .