Comprehensive profiling of MDM2/TP53 genomic aberration in Chinese patients with diverse malignancies.

Abstract

e13508 Background: Murine double minute-2 (MDM2) has increasing clinic relevance as preclinical and early clinical evidences have showed that the MDM2 inhibitors are promising alternative treatments for patients with MDM2-amplified (-amp) and TP53-wild-type (-WT) tumors by preventing TP53 protein degradation. However, exploration into genomic landscape of MDM2/TP53 across various solid tumors in Chinese patients is still limited. Methods: Formalin-fixed, paraffin-embedded (FFPE) tumor samples were collected from 10010 Chinese patients with solid tumors and subjected to a clinical-grade next-generation sequencing (NGS)-based 450 gene panel testing carried out by a College of American Pathologists (CAP) accredited and Clinical Laboratory Improvement Amendments (CLIA) certified laboratory. Genomic alterations (GAs) including single base substitutions, short and long insertion/deletions (Indels), copy number variations, gene fusions, and rearrangements were analyzed. Tumor mutational burden (TMB) was measured by a NGS algorithm. Results: Amplification of MDM2 occurred in 3.3% of Chinese patients. MDM2-amp was detected most frequently in soft tissue sarcoma (STS, 11.4 %), melanoma (10.3 %) and osteosarcoma (6.3 %). Notably, MDM2-amp was revealed to be mutually exclusive with TP53-mut in most tumor types other than esophageal carcinoma (93.9 %), head and neck carcinoma (68.4%) and ovarian carcinoma (50 %). Tumors with highest frequencies of MDM2-amp/ TP53-WT were melanoma (100%), osteosarcoma (100%) and urothelial carcinoma (100 %). The most common co-altered genes accompanied with MDM2-amp were FRS2 (84%), CDK4 (38%), EGFR (26%), TP53 (17%) and GLI1 (14%). 82.8% patients who had one or more co-alterations potentially targetable with either FDA-approved or investigational agent. Moreover, TMB of MDM2-amp tumors were significantly lower than that of MDM2-WT and MDM2-mutation (-mut) tumors (median TMB: 3.1 vs. 4.6 vs. 10.8, p < 0.001 respectively). Conclusions: MDM2 amplification was found in 3.3% of 10010 Chinese cancer patients, 83.4% of whom harbored wild-type TP53 that were potentially responsive to MDM2 inhibitors. In addition, 82.8% of the patients with MDM2-amp harbored genomic co-alterations and were potentially therapy targetable. This study provided insights into identifying patients who might potentially benefit from anti-MDM2 therapies.