TisCRT-LAPC: A phase II study of tislelizumab combined with nab-paclitaxel and gemcitabine (AG) followed by consolidative radiotherapy in locally advanced pancreatic cancer (LAPC).

e16350 Background: We have previously reported that consolidative chemoradiotherapy following induced chemotherapy is an optimal regimen for LAPC. This study aimed to evaluate the clinical benefit of tislelizumab (anti-PD-1) plus AG chemotherapy sequenced by consolidative radiotherapy for therapy-naive LAPC. Methods: Patients (pts) with LAPC were enrolled and received tislelizumab (TIS) 200mg Q3W, nab-paclitaxel 125 mg/m 2 and gemcitabine 1,000 mg/m 2 on days 1 and 8 every three weeks for 6 cycles. Those who did not progressed continued to receive radiotherapy and tislelizumab. After that, tislelizumab and gemcitabine were ongoing until progression. The primary endpoint was 12-month progression-free survival rate, and secondary endpoints included objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), safety and biomarker explore. Results: From April 2021 to December 2023, 30 pts were enrolled, 29 pts completed at least one efficacy assessment, 1 dropped out due to jaundice on liver damage for more than 6 weeks without medication. 17 males and 13 females with a median age of 58.5 years. 12.5% (3/24) progressed after TIS+AG treatment and did not receive radiotherapy, 87.5% (21/24) had completed radiotherapy and 5 pts were still receiving TIS+AG treatment. ORR was 31.0%, and DCR was 96.6%, respectively. The median follow-up time was 14.0 months, and the median PFS was 11.2 months (95%CI,7.6-26.6). The median OS was not reached. 6-month and 12-month PFS rates were 84.2% and 44.3%, respectively. Most patients (27/30) showed serum CA19-9 decline with different degrees.The most common treatment-emergent adverse events (TEAEs) were myelosuppression, rash, and fatigue. Grade 3/4 TEAEs were neutropenia in 5 patients, anemia in 1 patient, and rash in 1 patient. Immune-related AEs included 1 Grade-1 myocarditis, 1 Grade-1 pneumonia and 1 Grade-3 disfunction of liver. Conclusions: This study demonstrates the effectiveness and manageable safety of tislelizumab combined with AG chemotherapy sequenced by radiotherapy for LAPC. Exploratory analysis of correlative biomarkers suggests that KRAS ctDNA negative at baseline may be a pedictive markers benefit with treatments. Clinical trial information: ChiCTR2000040872.