Abstract 1610: Primary cultures from malignant pleural effusions and ascites for drug screening in personalized therapy

Background: A significant percentage of patients (p.) with solid tumors present with pleural effusion or ascitic fluid during disease history. Although isolation of viable malignant cells from these fluids for drug screening and other experimental purposes have been described in the literature, the success rate in obtaining pure cultures is low and the technique is rarely employed in the clinical setting. Here, we present the results of the implementation in our hospital of routine primary culture and subsequent drug testing from pleural effusions and ascites. Methods: 22 pleural effusions (PE) and 11 ascitic fluid from 33 p. were collected; three colon, one esophagous, one melanoma, eight ovarian, one pancreatic and 19 lung cancer. Total cells were isolated by centrifugation, erythrocytes discarded by density gradient and the remaining cells cultured in RPMI + 20%FBS. Primary cultures were genotyped by next generation sequencing (NGS), FISH, qPCR and nCounter. The antitumor effects of several drugs were tested by MTT, including tyrosine kinase, PARP and KRAS inhibitors and chemotherapeutic agents such as cis-platinum or pemetrexed. Results: Primary cultures were attempted from 33 malignant pleural effusions and ascites samples. Cells grew ≥3 passages and were genotyped in 28/33 cases (84%). Eleven primary cultures were pan-negative by NGS, suggesting that they derived either from non-tumor cells or from a minor sub-clone within the tumor. In contrast, 17 primary cultures showed alterations in oncogenes or tumor supressor genes, allelic fractions were ≥70% in 11 cases. Synchronous liquid biopsies or FFPE biopsies were available for the 17 primary cultures; the same genetic alterations were present in all cases. Five primary cultures with drivers at ≥70% allelic fraction (KRAS G12C; ALK and ROS1 fusions; MET and FGFR1 amplifications) were used for MTT assays. In the three cases where the patient was administered the same drugs tested in primary cultures, results were concordant. Conclusions: Primary culture of pleural effusions and ascites can be implemented in the clinical setting with a significant success rate. Drug testing in primary cultures can be of help in treatment selection. Citation Format: Cristina A. Aguado, Beatriz Garcia, Andrés Aguilar-Hernández, Alejandro Martínez-Bueno, Marta Vives-Usano, Florencia Garcia-Casabal, Ruth Román, Ekaterina Meshoulam, Erika Aldeguer, Nuria Jordana-Ariza, Juan José García-Mosquera, Carlos Cabrera, Santiago Viter