167P - TisCRT-LAPC: A phase II clinical trial of Tislelizumab plus chemotherapy(nab-paclitaxel and gemcitabine, AG)followed by consolidative radiotherapy in locally advanced pancreatic cancer (LAPC)

Background

Previously, we have demonstrated 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-naïve LAPC.

Methods

Patients were given tislelizumab 200mg Q3W, nab-paclitaxel 125 mg/m² and gemcitabine 1,000 mg/m² on days 1 and 8 every three weeks for 4-6 cycles. Those who did not progress continued to sequence radiotherapy and tislelizumab 200 mg Q3W. Then, maintenance chemotherapy with anti-PD-1 was 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), and safety. The Data cutoff date for this interim analysis was August 30, 2022.

Results

From April 2021 to August 2022, 15 patients were enrolled. Twelve patients completed at least one efficacy assessment. 4 of 12 patients had an optimal partial response (PR), 7 patients had stable disease (SD), and 1 had progressive disease (PD). ORR was 33.3%, and DCR was 91.7%, respectively. Most patients (10/12) showed serum CA19-9 decline with different degrees, but only PR patients (3 cases) fell within normal ranges and declines exceeding 93.7%.The median follow-up time was 283 days, and the median PFS was 266 days (95%CI,176-not reached). The median OS was not reached. 6-month and 12-month PFS rates were 70.7% and 44.2%, separately. Notably, the12-month OS rate was 100%. The most common treatment-emergent adverse events (TEAEs) were myelosuppression, rash, and fatigue. Grade 3/4 TEAEs were neutropenia in 4 patients, anemia in 1 patient, and rash in 1 patient. Immune-related AEs included 1 Grade-1 myocarditis and 1 Grade-1 pneumonia, and no deaths occurred.

Conclusions

Our data suggest that tislelizumab combined with AG chemotherapy sequenced by radiotherapy for LAPC provided encouraging efficacy with reasonable tolerability. Significant CA19-9 decline is predictive of therapeutic response.

Clinical trial identification

ChiCTR2000040872.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.