OBJECTIVES: To evaluate the cost-effectiveness of atezolizumab and vemurafenib plus cobimetinib vs. vemurafenib plus cobimetinib alone in patients with newly diagnosed unresectable BRAF V600 mutated metastatic melanoma from the US healthcare perspective.

METHODS: This economic evaluation study used a three-state partitioned survival model to assess the cost-effectiveness of the triplet combination of PD-L1 inhibitor atezolizumab plus BRAF inhibitor vemurafenib plus MEK inhibitor cobimetinib. The observed overall survival curves and progression free survival curves were digitized from the IMspire150 trial (January 2017 – April 2018) and the long-term survivals (over a life-time horizon) beyond the end of the study were extrapolated using seven different survival models. Life-years (LYs) gained and quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratio (ICER) expressed as cost per LYs and per QALYs saved were estimated. The cost and health preference data were collected from a literature review.

RESULTS: Adding atezolizumab to vemurafenib and cobimetinib provided an additional 3.267 QALYs compared to doublet regimen of vemurafenib plus cobimetinib, at an ICER of $271,669/QALY, which is not considered cost-effective at the willingness-to-pay (WTP) threshold of $150,000/QALY. However, the scenario analyses found that atezolizumab combined with vemurafenib plus cobimetinib could be cost-effective at a 20-year (ICER, $121,432/QALY) and 30-years ($98,092/QALY) time horizons when both strategies were stopped after two years of treatments, and over a lifetime horizon ($122,220/QALY) when immunotherapy was stopped after two years of treatment.

CONCLUSIONS: Combining immunotherapy with targeted therapies can lead to significant survival benefit for patients with BRAF V600 mutated advanced melanoma but was not cost-effective at a WTP value of $150 000/QALY. Adding the immunotherapy to the targeted therapies could be cost-effective over a lifetime horizon if long-lasting immunotherapeutic effect was sustainable and immunotherapy was stopped after 2 years in the absence of disease progression.