Abstract 1299P
Background
Pancreatic cancer is a kind of lethal malignant tumors with poor sensitivity to chemoradiotherapy and low resection rate. This study is to evaluate the safety and efficacy of anti-PD-1 inhibitor plus nab-paclitaxel and gemcitabine chemotherapy (AG) followed by concurrent hypofractionated radiotherapy with simultaneous integrated boost (SIB) as induction therapy for patients with borderline resectable (BRPC) and locally advanced pancreatic cancer (LAPC).
Methods
Patients with LAPC or BRPC were given gemcitabine 1000mg/m2 and nab-paclitaxel 125mg/m2 on day 1, 8, along with Tislelizumab 200 mg on day 1 Q3W. After two cycles of treatment, hypofractionated radiotherapy with SIB (high dose field: 50 Gy/10 fractions, the remainder: 30 Gy/10 fractions) were done concurrently. Reassess for surgery after 4 cycles of treatment. The primary outcomes were ORR and R0 resection rate. Secondary outcomes included safety, mOS, mPFS and postoperation pathological stage. Plasma ctDNA was detected during treatment.
Results
From May 2020 to October 2021, 25 patients were enrolled with a median age of 62 years old. The ORR was 60% and DCR was 100%. 10 patients underwent resection, 2 of them achieved PCR and one achieved MPR. The R0 resection rate was 90%. 12-months OS rate was 79.4% and 6-months PFS rate was 82.8%. No grade 5 adverse event was observed. Grade 3 or 4 neutropenia and thrombocytopenia were observed both in 2 patients (8%). Non-hematological toxic effects were jaundice (16%), increased ALT/AST level (20%), vomiting (16%), rash (12%). The analysis of ctDNA showed that patients who had a > 50% decline between first clinical evaluation (T2) and baseline (T1) in maximal somatic variant allelic frequency(maxVAF) had a longer PFS and higher response rate and maxVAF decline (T1-T2, > 50%) significantly improved the resection rate.
Conclusions
Anti-PD-1 inhibitor plus AG chemotherapy followed by concurrent hypofractionated radiotherapy provided remarkable efficacy with reasonable tolerability as induction therapy for patients with BRPC and LAPC. ctDNA is a promising biomarker to predict the prognosis.
Clinical trial identification
ChiCTR2000032955.
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
National Key Research and Development Program of China(2020YFA0713804); Special Fund of Health Science and Technology Development of Nanjing (YKK20080).
Disclosure
All authors have declared no conflicts of interest.