Background: KIT-directed tyrosine kinase inhibitors such as imatinib have demonstrated benefits in KIT-mutant (KIT+) 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 11L576P . 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 KIT+ and wild-type KIT (KIT-) mucosal, acral, and CSD melanoma (n = 57). Stage II accrued only KIT+ tumors (n = 30). To enrich the trial for KIT+ 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 KIT+ 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 KIT+ melanoma. Cancer 2017;123:2688-97. © 2017 American Cancer Society.
Keywords: KIT mutation; acral; dasatinib; melanoma; mucosal; vulvovaginal.
© 2017 American Cancer Society.