A phase 2 trial of dasatinib in patients with locally advanced or stage IV mucosal, acral, or vulvovaginal melanoma: A trial of the ECOG-ACRIN Cancer Research Group (E2607).

BACKGROUND: KIT-directed tyrosine kinase inhibitors such as imatinib have demonstrated benefits in KIT-mutant (KIT1) mucosal, acral, vulvovaginal, and chronically sun-damaged (CSD) melanoma. Dasatinib has superior preclinical activity in comparison with other tyrosine kinase inhibitors against cells with the most common KIT mutation, exon 11(L576P). The ECOG-ACRIN E2607 trial assessed dasatinib in patients with these melanoma subtypes. METHODS: Patients received 70 mg of oral dasatinib twice daily. The primary objective for this 2-stage phase 2 trial was response rate. Stage I was open to KIT1 and wild-type KIT (KIT-) mucosal, acral, and CSD melanoma (n = 57). Stage II accrued only KIT1 tumors (n = 30). To enrich the trial for KIT1 tumors, vulvovaginal melanoma was added, and CSD melanoma was removed from eligibility. Secondary objectives included progression-free survival (PFS), overall survival (OS), and safety. RESULTS: From May 2009 to December 2010, the first stage enrolled 57 patients. Among the evaluable patients, 3 of 51 (5.9%) achieved a partial response: all were KIT-. Stage II closed early because of slow accrual (November 2011 to December 2015). In stage II, 4 of 22 evaluable patients (18.2%) had a partial response; the median duration was 4.2 months. The median PFS was 2.1 months (n = 73; 95% confidence interval [CI], 1.5-2.9 months). The median OS was 7.5 months (95% CI, 6.0-11.9 months). In exploratory analyses, no differences were seen in PFS or OS with the KIT status or subtype. Dasatinib was discontinued because of adverse events in 9 of 75 patients (12%). CONCLUSIONS: The dasatinib response rate among KIT1 melanoma patients was low. In view of its clinical activity, it is recommended that imatinib remain the KIT tyrosine kinase inhibitor of choice for unresectable KIT1 melanoma. (C) 2017 American Cancer Society.