PET-guided Switch from Immunotherapy to Targeted Therapy in a Metastatic Melanoma Patient: a personalized approach

An early identification of non-responders in oncology is of crucial importance to rapidly switch treatment regimens. Here we report a positron emission tomography, (PET)-guided switch from immunotherapy to targeted therapy in a patient affected by metastatic melanoma. We describe the case of a 78-years-old male patient diagnosed with nodular melanoma, submitted to baseline PET/CT with 18fluorodeoxyglucose (18F-FDG) that showed cutaneous and skeletal metastases (stage IV). The patients started immunotherapy with pembrolizumab. A PET/CT performed 3 months after the start of immunotherapy demonstrated progressive metabolic disease both at skeletal and cutaneous level, confirmed also by the biopsy. As patients resulted positive for BRAF V600k mutation, treatment regimen was rapidly switched to combined anti-BRAF/MEK targeted therapy. The PET/CT performed 3 months later, showed almost complete metabolic response. Ten months after the beginning of targeted therapy, the patient continues to present a durable metabolic response. PET/CT with 18F-FDG may help in monitoring the response to treatment in metastatic melanoma thus defining personalized therapeutic pathways.