Single Institution Experience with Immune Checkpoint Inhibitors in Vulvar and Vaginal Melanomas.

Objectives: This study aimed to report clinical outcomes of patients with vaginal melanoma (VaM) or vulvar melanoma (VuM) who were treated with immune checkpoint inhibitors (ICI) and discuss the development of immune-related adverse events (irAE).

Materials and methods: This is a retrospective case series of patients diagnosed with VaM or VuM between July 2011 and September 2022 at the University of Virginia, Emily Couric Clinical Cancer Center. Patient demographics, disease characteristics, treatment outcomes, and adverse events were abstracted. The primary outcome was incidence of irAE.

Results: Eight patients were included in this study, four with VaM and four with VuM. Most (n = 6) had local or regional disease at first presentation, and 25% (n = 2) presented with distant metastasis. All patients received a CTLA-4 inhibitor and 75% (n = 6) received PD-1 inhibitor alone or in combination with a CTLA-4 inhibitor. Most (75%, n = 6) patients experienced irAE. Of those who had irAE, 83% (n = 5) required therapy interruption or discontinuation. Most (66%, n = 4) underwent ICI rechallenge of which 75% (n = 3) experienced subsequent irAE. Of all patients in the series, 75% of patients (n = 6) had partial or complete response to ICI.

Conclusion: This series is the first to detail incidence of irAEs and ICI rechallenges in vulvovaginal melanoma. Our findings indicate that while ICIs are effective, their use is associated with significant irAE development. Rechallenge of ICI after irAE is feasible but associated with risk of recurrent/new irAE. Further studies are needed to better quantify this risk.