Switch to checkpoint inhibition after targeted therapy at time of progression or during on-going response: a retrospective single centre experience in patients with BRAF mutated melanoma.

BRAF + MEK inhibition is preferentially applied as first-line therapy in BRAF V600-mutated melanoma patients with unfavourable prognostic features, due to the ability of targeted therapy (TT) to induce rapid symptom control, decrease tumour burden and normalize lactate dehydrogenase (LDH) levels. In addition, short-term TT transiently increases tumour antigen presentation and tumour influx of T cells. Therefore, it might be favourable to switch TT to checkpoint inhibition (CPI) before progression (PD). We retrospectively analysed melanoma patients treated first line with TT (TT1) and who subsequently switched to CPI during response to TT (sDR group) or at progression upon TT (sPD group). We identified 74 patients (n = 37 sDR group and n = 37 sPD group). ORR to CPI was 27.0% in the sDR group versus 24.3% in the sPD group (p = .790). Median was PFS 2.5 months versus 1.2 months (p = .145), and median OS was 30.6 versus 14.1 months (p = .007). After adjusting for baseline differences and known prognostic factors, hazard ratios (HRs) favouring sDR were 0.89 for PFS upon CPI (p = .956) and 0.48 for OS (p = .055). Thus, patients switching to CPI during ongoing clinical benefit from TT do not have an inferior outcome. Due to baseline imbalances and small patient population, a favourable trend for the sDR group can be hypothesized only.