Background:
Immune checkpoint inhibitors are standard treatment for advanced melanoma. Pembrolizumab (programmed cell death-1 inhibitor) monotherapy is recommended as first-line treatment. However, real-world evidence on its efficacy and safety in Australia, a region with the highest melanoma incidence, remains limited.

Objective:
This study aimed to assess real-world outcomes of pembrolizumab in patients with advanced melanoma in Australia.

Methods:
A retrospective cohort study was conducted using national Pharmaceutical Benefits Scheme and National Death Index data via the Australian Bureau of Statistics DataLab. Patients who initiated pembrolizumab monotherapy for stage III/IV unresectable melanoma (1 January, 2017–30 June, 2022) were included. Kaplan–Meier analyses and multivariate Cox regressions were performed to assess overall survival and time to treatment discontinuation. Immune-related adverse events were inferred from corticosteroid and levothyroxine prescriptions. Subgroup analyses were performed by age (18–64, 65–84, ≥ 85 years) and sex.

Results:
Among 4127 patients, the median overall survival was 816 days. Mortality was higher in patients aged 65–84 years (adjusted hazards ratio 1.39, 95% confidence interval 1.24–1.56) and ≥85 years (adjusted hazards ratio 1.93, 95% confidence interval 1.69–2.21) versus 18–64 years. Median time to treatment discontinuation was 377 days, with a higher discontinuation rate in female individuals (adjusted hazards ratio 1.19, 95% confidence interval 1.09–1.29). Incident corticosteroid and levothyroxine prescriptions were observed in 19.3 and 7.6% of patients, respectively.

Conclusions:
Our findings align with clinical trials, demonstrating similar survival outcomes. Younger patients benefited more from pembrolizumab, while female individuals had shorter treatment durations. Further research is required to explore immune checkpoint inhibitor efficacy, safety, and treatment disparities.

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