BRAF inhibitor discontinuation and rechallenge in advanced melanoma patients with a complete initial treatment response.

BRAF inhibitors (BRAFi), a targeted therapy, are used to treat metastatic late-stage melanomas harbouring the BRAF-V600 mutation (found in about 50% of melanomas). The targeted therapy is generally maintained until tumour progression or major toxicity occurs, although responses are often limited in time. It is unknown whether melanoma patients achieving a complete response with targeted therapy can safely discontinue treatment. We retrospectively observed the clinical course of patients with metastatic melanoma who discontinued BRAFi therapy after achieving a complete response and those with an incomplete response combined with surgical removal of the remaining tumours. We also evaluated the effectiveness of BRAFi in these patients after recurrence. In 11 patients, the best response was diagnosed after a median BRAFi treatment duration of 105 (29-341) days. The median follow-up after BRAFi initiation was 769 (435-1765) days. Recurrence was observed in all 11 patients (100%), median: 82 (27-322) days. Five patients achieved a complete response, with a median progression-free survival after cessation of 136.5 (34-322) days versus 82 (27-144) days for six patients with an incomplete response combined with surgical removal of remaining tumours. Baseline characteristics and time to best response and to discontinuation did not influence the rate of relapse. Subsequently, eight patients were rechallenged with a BRAFi. The median progression-free survival time after BRAFi rechallenge was 222.5 (15-425) days. The three remaining patients received treatments other than BRAFi. Our findings may be valuable with respect to ongoing clinical trials of combinations of targeted therapies and immunomodulatory antibodies.