Identification of molecular targets in vulvar cancers.

OBJECTIVES

To identify molecular alterations that contribute to vulvar cancer pathogenesis with the intent of identifying molecular targets for treatment.

METHODS

After retrospective analysis of a database of molecularly-profiled gynecologic cancer patients, 149 vulvar cancer patients were included and tested centrally at a CLIA laboratory (Caris Life Sciences, Phoenix, AZ). Tests included one or more of the following: gene sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]), and gene amplification (C/FISH). A Fisher's exact test was used when indicated with a p-value≤0.05 indicating significance.

RESULTS

Median age was 65. 85% had squamous cell carcinoma (SCC) and 15% adenocarcinoma (ADC) histologies. 46% had metastatic (Stage IV) disease. Targeted hot-spot sequencing identified variants in the following genes: TP53 (33%), PIK3CA/BRCA2 (8%, 10%, respectively), HRAS/FBXW7 (5%, 4%, respectively) and ERBB4/GNAS (3%, 3% respectively). Mutations in AKT1, ATM, FGFR2, KRAS, NRAS (n=1, respectively) and BRAF (n=2) also occurred. Specific protein changes for targetable genes included clinically pathogenic mutations commonly found in other cancers (e.g. PIK3CA: exon 9 [E545K], RAS: G13D, Q61L, BRCA2: S1667X, BRAF: R443T, FBXW7: E471fs, etc.). Drug targets identified by IHC and ISH methodologies include cMET (32% IHC, 2% ISH), PDL1 (18%), PTEN loss (56%), HER2 (4% IHC, 2% ISH) and hormone receptors (AR, 4%; ER, 11%; PR, 4%). Comparisons between SCC and ADC identified differential rates for AR, ER, HER2 and GNAS with an increased presence in ADC (p-values all <0.05).

CONCLUSIONS

Molecularly-guided precision medicine could provide vulvar cancer patients alternative, targeted treatment options.