Use of PULSAR (personalized ultra-fractionated stereotactic adaptive radiotherapy) as consolidation with immune checkpoint inhibition in the treatment of pediatric metastatic melanoma.

We present a case of extensive and bulky pediatric metastatic melanoma originating in the head and neck which markedly responded to combination therapy with anti-programmed cell death (PD-1) inhibition and consolidative personalized ultra-fractionated stereotactic adaptive radiotherapy (PULSAR). After surgical debulking with neck dissection, the patient was initially treated with anti-PD-1 and anti-cytotoxic T-lymphocyte associated protein 4 (CTLA-4) dual checkpoint blockade immunotherapy, but quickly had disease progression. He was transitioned to a different anti-PD-1 immunotherapy in combination with tyrosine kinase inhibitors in conjunction with consolidative local therapy using PULSAR. This combination therapy achieved tumor response and progression-free status for one year before further disease progression at a separate site in the mediastinum. Due to otherwise good disease control, single agent anti-PD-1 immunotherapy was continued and salvage PULSAR was administered to the progressive site, again resulting in tumor response and progression-free status for 6 months. None of the bulkier sites of gross disease had local progression after combination therapy. This case suggests that the synergistic effect of PULSAR and anti-PD-1 immunotherapy is efficacious for relapsed or refractory metastatic melanoma in pediatric patients. Clinical trial number: not applicable.