Anal cancer is rare and accounts for 3% of all gastrointestinal malignancies. However, incidence has risen over the past decades. The International Rare Cancers Initiative Anal Cancer Working Group recognized the evidence gap in clinical decision making for patients with advanced anal cancer as an area of unmet clinical need, prompting this global clinical trial comparing cisplatin plus fluorouracil (FU) versus carboplatin plus paclitaxel to set a standard of care.
Patients who had not received systemic therapy for advanced anal cancer were randomly assigned 1:1 to intravenous cisplatin 60 mg/m2 (day 1) plus FU 1,000 mg/m2 (days 1-4) every 21 days or carboplatin (area under the curve, 5; day 1) plus paclitaxel 80 mg/m2 (days 1, 8, and 15) every 28 days for 24 weeks, until disease progression, intolerable toxicity, or withdrawal of consent. Primary end point was objective response rate (ORR).
This multicenter randomized phase II trial was conducted in 60 different centers over a period of 4 years. Median follow-up was 28.6 months. A total of 91 patients were randomly assigned: 46 to cisplatin plus FU and 45 to carboplatin plus paclitaxel. ORR was 57% (95% CI, 39.4% to 73.7%) for cisplatin plus FU versus 59% (95% CI, 42.1% to 74.4%) for carboplatin plus paclitaxel. More serious adverse events were noted in the cisplatin plus FU arm (62%) compared with the carboplatin plus paclitaxel arm (36%; p= .016).
Median progression-free survival was 5.7 months (95% CI, 3.3 to 9.0 months) for cisplatin plus FU compared with 8.1 months (95% CI, 6.6 to 8.8 months) for carboplatin plus paclitaxel. Median overall survival was 12.3 months for cisplatin plus FU (95% CI, 9.2 to 17.7 months) compared with 20 months (95% CI, 12.7 months to not reached) for carboplatin plus paclitaxel (hazard ratio, 2.00; 95% CI, 1.15 to 3.47; p=.014).
In conclusion, this is the first international randomized trial to our knowledge conducted in chemotherapy-naïve advanced anal cancer. Although there was no difference in ORR, the association with clinically relevant reduced toxicity and a trend toward longer survival suggest that carboplatin plus paclitaxel should be considered as a new standard of care.
Rao S, Sclafani F, Eng C et al. International Rare Cancers Initiative Multicenter Randomized Phase II Trial of Cisplatin and Fluorouracil Versus Carboplatin and Paclitaxel in Advanced Anal Cancer: InterAAct. J Clin Oncol. 2020 Jun 12;JCO1903266.