Abstract 6497: Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture

Abstract

Abstract Introduction and Objectives: Gastric and pancreatic cancers lack effective therapies, leading to low survival rates particularly in the metastatic setting. Fibroblast growth factor receptor 2 (FGFR2) amplification and fusions with TACC2 appear in 5.5% and 2.1% of gastric tumors, respectively. In pancreatic cancers, the KRAS p.G12C mutation is limited to 1-2% of cases. FDA has recently approved drugs targeting both alterations, pemigatinib and infigratinib for cholangiocarcinoma with FGFR2 fusions; sotorasib and adagrasib for KRAS p.G12C mutant lung cancers. Here, we report the initiation of primary cultures that can be used as preclinical models for testing antitumor agents in gastric and pancreatic tumor cells. Materials and Methods: Pleural effusions were collected from a gastric and a pancreatic cancer patient, both metastatic. Cells were isolated by centrifugation, cultured for 2-3 months in complete medium and genotyped using next generation sequencing (NGS) and RNA nCounter hybridization. Primary cultures were treated with specific drugs depending on their molecular alterations and clinical guidelines. Cell viability was determined by MTT. Results: Tumor cells from the pleural effusion of the gastric cancer patient were grown in suspension. NGS and nCounter revealed a FGFR2-TACC2 fusion, a FGFR2 amplification (160 copies) and a TP53 p.G245S mutation (100% variant allele fraction, VAF). The fusion and the amplification were confirmed by FISH. Cells were sensitive to erdafitinib, with IC50=40 nM in MTT assays. Irinotecan, 5-fluorouracil and cisplatin were also tested; IC50 were below the described plasma Cmax in the first two cases. The patient was treated with first-line fluoropyrimidine and oxaliplatin with partial response and a 5-month progression-free survival. Due to rapid deterioration, 2nd line treatment was not administered. The tumor cells from the pancreatic cancer patient were adherent, NGS revealed a KRAS amplification (9 copies) accompanied by a KRAS p.G12C mutation (81% VAF) and a TP53 p.R175H mutation (99% VAF). MTT assays were performed to determine the cells’ response to oxaliplatin, 5-fluorouracil, irinotecan, gemcitabine, nab-paclitaxel, adagrasib and sotorasib. IC50s below plasma Cmax were found in the last three cases. Remarkably, the IC50 for sotorasib was 100 nM and for adagrasib was 300 nM. The patient was treated with first-line gemcitabine and nab-paclitaxel with partial response but discontinued after three months due to hematological toxicity. Conclusions: Primary cultures can be initiated from malignant pleural effusions and used for genetic characterization and drug sensitivity profiling. Primaries with specific alterations can be employed as preclinical models to test targeted therapies. Citation Format: Silvia Garcia-Roman, Ekaterina Meshoulam Nikolaeva, Juan José García Mosquera, Mónica Garzón Ibáñez, Ruth Roman, Sonia Rodríguez, Cristina Rodríguez, Clara Mayo de las Casas, Rafael Rosell, Miguel A. Molina-Vila, Cristina Aguado Esteban. Molecular characterization and drug sensitivity of a gastric FGFR2-TACC2 and a pancreatic KRAS p.G12C primary culture [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6497.