Anti-PD1 therapy in patients with metastatic melanoma: A single centre experience

Background: The introduction of anti-PD1 checkpoint inhibitors: pembrolizumab and nivolumab has changed the treatment landscape of stage IV melanoma. Clinical trials reported response rates between 21% and 32%.2 Grade 3-4 adverse events ranged between 5% and 14%.1,2 A single-center experience of safety and efficacy of pembrolizumab, or nivolumab in treating stage IV melanoma were analyzed in this presentation. Methods: Records of patients from The Canberra Hospital between January 1, 2014 to January 30, 2016 receiving either nivolumab or pembrolizumab were reviewed retrospectively. Patients who received prior anti-CTLA4 inhibitor, BRAF-inhibitors, surgical metastatectomy or radiotherapy were also included in the analysis. Results: Forty patients with complete data were identified. Median duration of treatment was 5 months. Median age was 73 (37-88). All 40 patients had stage IV disease. One patient had stage M1a (2.5%), 16 patients stage M1b (40%) and 23 patients stage M1c (57.5%). Thirteen patients (32.5%) had brain metastases. Three patients (7.5%) had received prior BRAF inhibitors and twenty-two (55%) had received prior Ipilimumab. Two patients had complete response (5%), eight patients (20%) had partial response and eighteen had prior partial response and currently have stable disease (45%). The clinical response rate was 70%. Twelve patients (30%) had progressive disease. Twenty-two patients (55%) experienced any degree of adverse reactions but no patients experienced grade IV toxicity. There were five patients (12.5%) who had treatment discontinuation due to toxicity. The most common toxicities were pruritus, fatigue, generalized myalgia/arthralgia and rash. Rare side effects experienced included autoimmune neuropathy, pneumonitis and nephritis. Conclusions: Treatment of stage IV melanoma with pembrolizumab and nivolumab in our center had comparable safety and efficacy to the published literature