Feasibility and Safety of 3-Weekly Carboplatin/Paclitaxel Regimen in Advanced Squamous cell Carcinoma of the Anal Canal

Introduction: Anal cancer is a rare disease, and there is a lack of phase 3 studies in the advanced setting. Currently, the standard treatment is based on interAACT phase 2 study using Carboplatin (C) (AUC 5, D1q28) plus Paclitaxel (P) (80 mg/m2, D1,8,15q28). This study demonstrated a median OS of 20m, a response rate of 59% and serious adverse events in 36% of patients (pts). However, this regimen requires more infusions and hospital visits than a 3-weekly CP regimen, resulting in high social and financial cost. Objective: To retrospectively access safety and efficacy of treatment with 3-weekly CP in advanced SCCA. Methods: We performed a single-center retrospective analysis of patients (pts) who received first-line treatment with 3-weekly CP for inoperable locally recurrent or metastatic SCCA between Jun/2011 and Jun/2018. Study data were collected using REDCap®. Survival analyses were estimated with the Kaplan-Meier method and compared by log-rank test. Prognostic factors were evaluated by Cox regression. Results: 47 patients were included. Median age was 57 years, 60% (n=28) were female and 21% (n=10) HIV positive.16% (n=7) had metastatic disease at diagnosis. The majority of pts (n=42) were treated with paclitaxel (P) 175 mg/m2 plus carboplatin (C) AUC 5 every 3 weeks. The median number of cycles was 4 and dose reduction by toxicity was necessary for 30% (n=14). Grade 3/4 adverse events were neutropenia 19% (n=9), anemia 4% (n=2), fatigue 4% (n=2), neuropathy 2% (n=1). Two pts had interruption due to toxicity and no treatment-related death. 64% of patients benefited from treatment, 4% with complete response. The median overall survival (OS) was 10 months(m). In a multivariable analysis, HIV-positive (HIV+) status (HR 3.1; 95%CI 1.8-8.4; p 0.001) and ECOG 2/3 (HR 3.9; 95%CI 1.2-8.1; p 0.01) showed a negative impact on OS. Median OS was 16m for HIV- vs 4m for HIV+ group; and 20m for ECOG 0/1 vs 4m for ECOG 2/3. Conclusion: The present study suggests that 3-weekly CP has similar outcomes to the InterAACT regimen. Nevertheless, pts who are HIV+ or have ECOG 2/3 had poor outcomes and other treatment strategies should be studied for these pts.