Genetic characteristics and response to systemic therapies of acral lentiginous melanoma at a tertiary care center—a retrospective review

Background: Acral lentiginous melanoma (ALM) is an aggressive subtype of cutaneous malignant melanomas that accounts for 50-80% of melanomas in ethnic minorities. Studies on the genetic profile of these tumors largely result from cohorts in Europe, Asia, and Latin America, few inclusive of Black patients. Objective: We aim to describe the clinicopathological and genetic characteristics in a diverse cohort of ALM patients. Methods: A retrospective analysis of 93 patients with a pathology confirmed diagnosis of ALM between March 1984 and October 2020 was conducted at a large tertiary care center. Melanoma mutation panel testing for frequently mutated regions of the BRAF, NRAS, KIT and PIK3CA genes were reviewed in patient records when available. Results: Of the 93 patients identified, 62.4% were Caucasian, 25.8% Black, 4.30% Hispanic, 4.30% Asian, and 3.22% identified as other. Fourteen of 17 patients receiving targeted or immunologic agents experienced disease progression during treatment, including all patients with a BRAF V600E mutation. Limitations: This was a single-center retrospective analysis. Conclusion: Response to targeted and immunologic therapies in ALM patients was overwhelming poor, particularly in BRAF V600E-mutated tumors in contrast to the positive prognosis associated with BRAF V600E mutations in other advanced cutaneous melanoma subtypes.