Long-term drug costs per life-month gained associated with first-line treatments for unresectable or metastatic melanoma

Abstract

Background: For unresectable or metastatic melanoma, first-line ipilimumab has demonstrated long-term survival benefits over a 7-year period. First-line treatment with BRAF inhibitors has demonstrated efficacy in clinical trials with up to 3 years of follow-up. The long-term comparative efficacy and costs of ipilimumab and BRAF inhibitors are unknown. Methods: Patient-level data from 12 clinical studies for ipilimumab were used. Survival data were extracted from included clinical trials for BRAF inhibitors based on a systematic literature review. Different parametric survival models, including exponential, Gompertz, log-normal, and Weibull models, were used to fit reported overall survival (OS) data and to project long-term survival for BRAF inhibitors. Survival benefits were measured in terms of total life-months gained as calculated by the area under the curve of OS Kaplan-Meier curves for the observed ipilimumab data and projected BRAF inhibitor data. Total life-months gained and cumulative costs per life-month gained were compared between ipilimumab and BRAF inhibitors. Results: The systematic literature review identified six randomized-controlled trials of BRAF inhibitors for subsequent analyses. With 7-year follow-up, ipilimumab was associated with a total of 28.5 life-months gained. Based on the Weibull model, the extrapolated total life-months gained for BRAF inhibitors were 26.5 months for dabrafenib, 21.3 months for trametinib, 14.3 months for vemurafenib, and 24.6 months for dabrafenib + trametinib. In sensitivity analyses, extrapolated total life-months gained varied across the three other models, ranging from 13.7 to 36.8 months across therapies. Cumulative costs per life-month gained with ipilimumab decreased steadily over time, while the costs remained constant for BRAF inhibitors due to continuous dosing. By year 3, cumulative costs per life-month gained were the lowest with ipilimumab; by year 7, the costs were $4281 for ipilimumab, compared with $8920 for dabrafenib, $10,211 for trametinib, $11,002 for vemurafenib, and $19,132 for the dabrafenib + trametinib combination therapy. Conclusions: Ipilimumab was associated with a better long-term cost-per-life month compared to BRAF agents. Long-term extrapolation of survival with BRAF agents was uncertain, and showed no evidence of prolonged survival compared to ipilimumab.