Genomic biomarker discovery of first-line gemcitabine/nabpaclitaxel treatment in Chinese advanced pancreatic carcinoma patients.

Abstract

436 Background: Pancreatic carcinoma is one of the most lethal malignancies worldwide and is characterized by extremely poor prognosis. Gemcitabine plus Nab-paclitaxel (GNp) has been recommended by international guidelines for first-line treatment of locally advanced or metastatic pancreatic carcinoma. However, exploration into molecular biomarkers of GNp treatment is still limited. This study aims to observe and evaluate the efficacy and safety of first-line GNp treatment of pancreatic carcinoma, and to explore potential predictive and prognostic biomarkers to screen advantageous population. Methods: From December 20, 2018 to July 6, 2020, patients with metastatic pancreatic carcinoma, who received first-line GNp treatment, were enrolled. The primary endpoint was progression-free survival (PFS), and the secondary endpoints were overall survival (OS), overall response rate (ORR), disease control rate (DCR), and adverse events (AE). Patients were collected formalin fixed paraffin embedded (FFPE) samples and sequenced by a next-generation sequencing (NGS)-based 450 gene panel carried out by OrigiMed, a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory. Results: In this study, tissue samples from 101 patients were assessed by NGS, including 58 (57.4%) primary tissues and 43 (42.6%) metastasis tissues. So far, 72 patients were available for efficacy analysis, the ORR and DCR were 38.2% and 77.9%, respectively, and were similar between patients sampled from primary lesions and metastasis lesions. The PFS and OS were 176 days and 308 days, respectively. The most frequently mutated genes were KRAS (91.9%), TP53 (76.8%), CDKN2A (32.3%) and SMAD4 (26.3%). Germline pathogenic BRCA2 mutations were detected in 3 (3.0%) patients, while somatic mutations of BRCA2 were found in 2 (2.0%) patients. For KRAS, missense mutations resulted in single amino acid substitutions primarily at G12 (88.1%), and lower frequencies at Q61 (4.0%) and V14 (1.0%). At G12, five different amino acid substitutions have been identified, with G12D (37.6%) the predominant mutation, G12V (32.7%), G12R (11.9%), G12C (3.0%) and G12A (1.0%). The ORR to AG treatment was significantly higher in TP53-alteration (-alt, 47.1%) than in TP53-wild-type (-WT, 11.1%) subgroups (p=0.01). Median OS times in CDKN2B-alt and CDKN2B-WT patients were 180 days and 323 days (p=0.029), respectively. Conclusions: Current evidence indicates that GNp is a valuable option for the first-line treatment of metastatic pancreatic cancer. TP53 may serve as a novel response-predictive gene for GNp treatment in pancreatic carcinoma. Overall survival was significantly prolonged in CDKN2B-WT patients compared with CDKN2B-alt patients. This study provided insights in identifying patients who might potentially benefit from GNp therapy. Clinical trial information: NCT03768687.