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

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. 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. 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. 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.