Number needed to treat (NNT) with pembrolizumab as an adjuvant therapy in resected patients with high-risk stage II (IIB and IIC) melanoma and its application to cost of preventing an event (COPE) in Mexico.

INTRODUCTION: Melanoma, responsible for most skin cancer deaths globally, has mortality rates expected to double by 2040. Pembrolizumab is a highly selective antibody approved for melanoma treatment and other cancers. Despite new treatments for melanoma, high treatment costs and long approval times limit patient access to new therapies. To support decision-making regarding metastatic melanoma therapies, a model was developed to calculate the number needed to treat (NNT) and the cost of preventing an event (COPE) using KEYNOTE-716 (NCT03553836) data.

METHOD: A cost-per-responder model comparing the clinical and economic impacts of pembrolizumab versus best supportive care (BSC) was developed considering a 52.8-month follow-up for recurrence-free survival (RFS) and distant metastasis-free survival (DMFS) in patients with resected high-risk melanoma. KEYNOTE-716 RFS and DMFS survival curves were used to calculate restricted mean survival time (RMST). The RMST was used to calculate NNT (NNTRMST). The NNTRMST calculates the NNT to result in a difference in mean survival time for a death or an event. NNTRMST is subsequently used to quantify COPE outcomes.

RESULTS: NNT for RFS was 5.3, reflecting the number of patients needed to treat to gain the additional difference observed in the mean RFS for resected high-risk type II (IIB and IIC) melanoma patients treated with pembrolizumab. For DMFS, the NNTRMST was 7.8. The estimated COPE to prevent an RFS or DMFS event was Mexican Peso (Mex $) 9,554,593 (2024) and Mex $13,961,427, respectively.

CONCLUSIONS: NNT values for RFS and DMFS data were both lower than the published average NNT value for current melanoma therapies. This demonstrated that fewer additional patients need to be treated in order to avoid a recurrence or a distant metastases event, compared to currently available melanoma therapies. The NNT and COPE highlight the clinical and economic impact of introducing pembrolizumab therapy for the treatment of patients in resected high-risk stage II melanoma.