LAUSR

e15046 Background: RNA Next Generation Sequencing (transcriptome) is a potential useful tool to predict chemoresistance to available anticancer drug therapy. A correlation between previous clinical resistance and drug resistance profiling according to RNA NGS results has been studied. Methods: Since March 2018, whole transcriptome RNA NGS has been performed using Ion-Torrent GeneStudio S5 System in fresh-frozen biopsies obtained from tru-cut or surgical excision procedures from patients with resistant metastatic cancer. We have selected patients with clinically unequivocal drug resistance to previous therapies (tumor progressing to ongoing therapies or less than six months of stopped therapy). Drugs evaluated includes anthracyclines, alkylating agents (temozolomide), platinum derivatives, taxanes, TOPO 1 inhibitors (irinotecan and topotecan), antimetabolites (fluoropyrimidines, gemcitabine, methotrexate and pemetrexed), and more recently, immune checkpoint inhibitors. Results: A total of 111 procedures have been performed. In 64 patients an unequivocal clinical resistance to previous therapies could not be demonstrated, so the analyses has been performed in 47 patients with a number of different tumor histologies: colorectal cancer (13 patients), ovary/peritoneum (8), pancreas (4), NSCLC (4), breast (3), prostate (3), sarcoma (3), head and neck (2), uterus (2), kidney, bladder, cholangiocarcinoma, stomach and cervix (1 patient each). One hundred and fifty two drugs have been used in these patients (Median 3, Range 1 to 8) previous to the RNA NGS procedure. Resistance profile has been found in 120 out of 152 (78.9% of coincidence), and a favourable profile has been found in 32 (21%) previously used drugs, that could be re-used again in these patients. RNA NGS procedure gives additional information about drugs not previously used that helps in the treatment selection for the patients. Conclusions: Transcriptome provide drug resistance information that correlates in 78.9% of drugs with the previous clinical information. However, in 21% of the previously used drugs transcriptome informs as potentially active and could be tried again in subsequent therapies. Transcriptome (RNA sequencing) provides useful clinical information for treatment decision in the vast majority of pretreated cancer patients.