Limited-duration anti-PD-1 therapy for patients with metastatic melanoma.

Purpose: To date, no clinical study has reported on the optimal treatment duration of PD-1 blockade in patients with metastatic melanoma. Worldwide, concern has been expressed that due to the high cost of anti-PD-1 therapy, it is not available for all patients. After approval of anti-PD-1 therapy as a first-line treatment, the Helsinki University Hospital institutional board for new drugs decided to treat the first patient cohort within a limited treatment duration program in order to offer this treatment to as many patients as possible.Patients and methods: The first 40 patients with metastatic melanoma initiating treatment at Helsinki University Hospital were to be treated within a six months maximum limited duration program. Patient follow-up was systematic according to a prospectively planned treatment protocol to enable evaluation of treatment efficacy and the safety of this treatment approach.Results: Thirty-eight patients were treated within the program. Seventeen out of these 38 patients completed the six-month regimen. Five discontinued treatment early due to toxicity, and 16 discontinued due to progressive disease. The response rate (RR) for all patients was 39%, but only 33% of these responses are ongoing. Median progression-free survival (PFS) for patients who completed the six-month therapy was 12 months (range, two to 44 months), and median overall survival (OS) has not yet been reached.Conclusions: Although RR is comparable to published data, the response duration is shorter. Based on our results, limiting treatment to only six months may increase the risk of shortening response duration.