Efficacy of pembrolizumab in advanced cancer of the vulva: a systematic review and single-arm meta-analysis

Introduction: Vulvar cancer carries a favourable prognosis in early stages. However, therapeutic options for advanced or recurrent cases are limited despite a variety of therapeutic modalities, such as extensive surgical resection, chemotherapy, and radiotherapy. The most important emerging treatment modalities are immune checkpoint inhibitors. This systematic review and meta-analysis aims to assess the efficacy and safety of pembrolizumab, an immune checkpoint inhibitor, in women with advanced vulvar cancer. Materials and methods: Following a comprehensive search, review, and appraisal, two relevant single-arm studies were included. Meta-analysis was conducted using R4.3.0 software and RStudio 2023.03.0, presenting the overall effect size with a 95% confidence interval. Heterogeneity was assessed using I(2 )and the Cochrane Q chi(2) statistics. Results: Out of 154 studies screened for eligibility, two single-arm studies involving 119 patients receiving pembrolizumab for advanced vulvar cancer were included. The pooled objective response rate (ORR) was overall 10% (95% CI: 0.00-0.84) and 9% (95% CI: 0.00-0.89) in the PD-L1 positive subgroup. In the intention-to-treat (ITT) population, 31% (95% CI: 0.04-0.85) exhibited any clinical benefit (complete response, partial response, or stable disease). In the ITT population at six months, progression-free survival (PFS) was 19% (95% CI: 0.01-0.82), and overall survival (OS) was 48% (95% CI: 0.08-0.90). At 12 months, PFS decreased to 9% (95% CI: 0.00-0.85), and OS was 33% (95% CI: 0.04-0.85). No statistically significant heterogeneity was observed in PFS and OS analyses. Discussion and conclusion: This study suggests that one-third of women with advanced or recurrent vulvar cancer may, without the influence of PD-L1 status, benefit from pembrolizumab treatment despite a decline in both PFS and OS at 12 months. These findings provide support for considering pembrolizumab in the treatment paradigm for this specific subset of cancer patients.