Response and survival of metastatic melanoma patients treated with immune checkpoint inhibition for recurrent disease on adjuvant dendritic cell vaccination

Vaccination with autologous dendritic cells (DC) loaded ex vivo with melanoma-associated antigens is currently being tested as an adjuvant treatment modality for resected locoregional metastatic (stage III) melanoma. Based on its mechanism of action, DC vaccination might potentiate the clinical efficacy of concurrent or sequential immune checkpoint inhibition (ICI). The purpose of this study was to determine the efficacy of ICI administered following recurrent disease during, or after, adjuvant DC vaccination. To this end, we retrospectively analyzed clinical responses of 51 melanoma patients with either irresectable stage III or stage IV disease treated with first- or second-line ICI following recurrence on adjuvant DC vaccination. Patients were analyzed according to the form of ICI administered: PD-1 inhibition monotherapy (nivolumab or pembrolizumab), ipilimumab monotherapy or combined treatment with ipilimumab and nivolumab. Treatment with first- or second-line PD-1 inhibition monotherapy after recurrence on adjuvant DC vaccination resulted in a response rate of 52%. In patients treated with ipilimumab monotherapy and ipilimumab-nivolumab response rates were 35% and 75%, respectively. In conclusion, ICI is effective in melanoma patients with recurrent disease on adjuvant DC vaccination.