Clinically advanced pelvic squamous cell carcinomas (pSCC) in men and women: A comprehensive genomic profiling (CGP) study.

Abstract

3130 Background: Given that the clinical manifestations, disease course, and treatment options for pSCC differ between tumor types, we performed CGP to examine possible genomic differences. Methods: 1,741 clinically advanced pSCCs including 230 penile (penSCC), 17 male urethral (murthSCC), 125 male anal (manSCC), 7 female urethral (furthSCC), 263 vulvar (vulSCC), 822 cervical (crvSCC), and 277 female anal SCCs (fanSCC) underwent hybrid capture-based CGP to evaluate all classes of genomic alterations (GAs). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. PD-L1 expression was determined by IHC (Dako 22C3). Results: HPV-16/18 detection was lowest in murthSCC and vulSCC and highest in manSCC, fanSCC, and crvSCC. TP53 GAs were inversely associated with HPV status. PIK3CA GA frequency varied (22-43%). DNA-damage response (DDR) GAs (e.g., BRCA1/2, ATM, others) were low ( < 1-3%) throughout. Cell-cycle GAs were most frequent in external cases (penSCC, furthSCC, vulSCC). MTOR pathway GAs ( PTEN, FBXW7) were the most frequently identified “actionable” GAs. FGFR3 GA were present in >5% of murthSCC, crvSCC, and fanSCC; other receptor-tyrosine kinase (RTK) targeted options were 1% in BRAF/ ERBB2. NOTCH1 GAs were present in > 15% of penSCC and vulvSCC. TMB ≥10 mut/Mb was >15% in manSCC, fanSCC, and crvSCC. PD-L1 low expression was > 25% in all pSCC except crvSCC and high expression was > 18% in all pSCC except urthSCC and manSCC. Conclusions: Despite similar histology, pSCC differ widely in GAs and HPV status. PIK3CA is the most frequent “targetable” GA followed by MTOR pathway and cell cycle; RTK targets are extremely rare. PARP inhibitor options appear low given the infrequent finding of DDR GAs. Anti-PD(L)1 could be considered in a number of cases based on TMB>10 mut/Mb and PD-L1 expression.[Table: see text]