Role of immune checkpoint inhibitors in metastatic uveal melanoma: a single-center retrospective cohort study.

ABSTRACT

BACKGROUND: Uveal melanoma is an orphan malignancy with very limited data on treatment options in metastatic setting. METHODS: In this single-center retrospective study, we describe real-world epidemiological and survival data on 121 metastatic uveal melanoma (MUM) patients registered in our institution. As a large tertiary referral center, almost 30% of all diagnoses in the Flemish region of Belgium were covered. Primarily, we determined whether introduction of immune checkpoint inhibitors (ICI) led to improved overall survival (OS) in MUM patients. Secondarily, response rates to ICI were assessed and we evaluated whether first-line ICI could be a valid alternative to liver-directed therapy (LDT) in liver-only disease. RESULTS: The initially perceived 10.8 months survival benefit from treatment with ICI disappeared after correction for immortality bias. By analyzing treatment type as time-varying covariate on OS, no significant benefit of ICI over other systemic therapies (HR = 0.771) or best supportive care (BSC) (HR = 0.780) was found. Also comparison of the pre-ICI versus ICI era showed no OS improvement after introduction of ICI in our center (p = 0.7994). Only liver-directed and local oligometastatic approaches were associated with a lower chance of mortality when compared to ICI (p = 0.0025), other systemic therapies (p = 0.0001) and BSC (p = 0.0003), yet without correction for selection bias. We reported overall response rates on ICI ranging from 8-15% and we found some support for neoadjuvant strategies with ICI resulting in remission or downsizing, allowing oligometastatic approaches later on. In first-line liver-only disease, median real-world progression-free survival and OS did not significantly differ between patients treated with LDT or ICI upfront (p = 0.2930 and p = 0.5461 respectively). CONCLUSION: Although we documented responses to ICI, our analyses do not demonstrate an OS benefit of ICI over alternative treatment strategies for MUM. However, local treatment options, whether liver-directed or for oligometastatic disease, may be beneficial and should be considered.