Abstract
As immune checkpoint inhibitors are rapidly developing into the standard of care for patients with advanced melanoma, the value of diagnostic metrics to predict response to immunotherapy is steadily increasing. Next-generation sequencing-based parameters include tumor mutation burden (TMB) and genomic amplification of PD-L1/PD-L2/JAK2 at 9p24.1. At present, there are limited studies documenting response to checkpoint blockade in 9p24.1-amplified solid tumors. Herein, we have compared a cutaneous melanoma with a mucosal melanoma, both with 9p24.1 amplifications and durable response to immunotherapy. Although the cutaneous melanoma had a high TMB, the mucosal melanoma had a lower TMB compared with the mean TMB for all melanomas within the institutional clinical sequencing cohort. In summary, PD-L1/PD-L2/JAK2 amplification was associated with durable response to therapy for both cases, and this genomic signature is a potential valuable metric in predicting response to immunotherapy.