Real-life comparison between immunotherapy and conventional chemotherapy in patients with advanced anal cancer after first-line treatment.

e15501 Background: Phase II study have suggested potential benefits of immunotherapy for selected populations based on specific biomarkers in first line therapy. However, there is a clear lack of evidence regarding the efficacy of immunotherapy in subsequent lines of treatment. The objective of this study is to evaluate the benefit of immunotherapy treatment in subsequent lines of therapy for patients with metastatic anal cancer. Methods: Investigators conducted a multicenter, retrospective, observational cohort study involving patients who experienced disease progression after first-line treatment for anal cancer. The study was carried out mainly at the AC Camargo Cancer Center in São Paulo, Brazil, with data collected from January/2007 to June/2024, focusing on patients in subsequent lines of treatment who received either immunotherapy or the phisicyan’s choice chemotherapy. The primary outcomes assessed were Overall Survival (OS) and Progression-Free Survival (PFS). It was considered p value < 0,05 statistically significant. Results: A total of 35 patients were enrolled in the study. Among them, 24 (68.3%) received chemotherapy as their second-line treatment, while 11 (31.4%) were treated with immunotherapy (Pembrolizumab, Nivolumab or Atezolizumab). Of these, six patients (17.1%) were HIV-positive, and 21 (60%) were classified as elderly (over 65 years). Treatment regimens included platinum-based combinations with fluoropyrimidine in 12 patients (34.3%) and taxanes in other 12 patients (34.3%). Median follow-up was 63,5 months (95% CI 54,9 – 72,2). The median overall survival in the immunotherapy group was 30 months (95% CI 12.0 – 47.9), versus 8 months (95% CI 5.2 – 10.7) in the chemotherapy with p value of 0,027. The median progression-free survival for patients receiving second-line treatment was 6.0 months (95% CI 1.6 – 10.3) in the immunotherapy group versus 4.0 months (95% CI 2.1 – 5.8) in the conventional chemotherapy cohort with p value of 0,102. Conclusions: Our findings indicate that immunotherapy significantly improves overall survival in patients with advanced squamous-cell anal cancer who had received one previous line of chemotherapy.