Melanoma of unknown primary: favorable survival persists in the immunotherapy era

Survival of patients with unfavorable prognosis cutaneous melanoma with increased use of immunotherapy agents: a population-based study in Belgium

BACKGROUND

Although metastatic cutaneous melanoma is associated with an unfavorable prognosis, innovative therapies including immunomodulating agents and targeted therapies have shown survival benefits in clinical trials. We assessed the impact of the introduction of innovative drugs into clinical practice on the survival of patients with metastatic cutaneous melanoma during the period 2004-2017, in Belgium. The evolution of associated expenses was also analyzed.

METHODS

This is a retrospective population-based study using data from the national Belgian Cancer Registry, compulsory health insurance, and administrative survival data. The immunomodulating drugs were ipilimumab, nivolumab and pembrolizumab, while targeted therapies included vemurafenib, dabrafenib and trametinib.

RESULTS

We did not identify a trend for improvement over time. Median survival (years) was 1.5 (95% CI: 1.1-1.8) in 2004-2008, 1.1 (95% CI: 0.8-1.5) in 2009-2013, and 1.6 (95% CI: 1.3-2.4) in 2014-2017, respectively. In contrast, survival improved in those with unknown primary tumor localization. In this group, median survival time was 2.0 (95% CI: 1.4-2.9) in the most recent period, while it was 1.1 (95% CI: 0.7-1.3) in 2009-2013, and 0.9 (95% CI: 0.6-1.2) in 2004-2008. The uptake of innovative drugs remained modest, with no drug being used by more than 30% of patients. Yearly expenditure was almost non-existent, and gradually increased, reaching several million euros in 2014-2017.

CONCLUSION

Patients with metastatic cutaneous melanoma who were diagnosed between 2004 and 2017 showed no apparent improvement in survival. In contrast, increased survival was observed in the subgroup of patients with unknown primary tumor localization.