Docetaxel, Cisplatin, and 5-fluorouracil (DCF) chemotherapy in the treatment of metastatic or unresectable locally recurrent anal squamous cell carcinoma: a phase II study of French interdisciplinary GERCOR and FFCD groups (Epitopes-HPV02 study)

Background: The squamous cell carcinoma of the anus (SCCA) is a rare disease, but its incidence is markedly increasing. About 15% of patients are diagnosed at metastatic stage, and more than 20% with a localized disease treated by chemoradiotherapy (CRT) will recur. In advanced SCCA, cisplatin and 5-fluorouracil (CF) combination is the standard option but complete response is a rare event and the prognosis remains poor with most disease progression occurring within the first 12 months. We have previously published the potential role of the addition of docetaxel (D). Among 8 consecutive patients with advanced recurrent SCCA after CRT, the DCF regimen induced a complete response in 4 patients, including 3 pathological complete responses. Then, the Epitopes-HPV02 study was designed to confirm the interest of DCF regimen in SCCA patients. Methods: This multicentre phase II trial assesses the DCF regimen in advanced SCCA patients. Main eligibility criteria are: histologically proven SCCA, unresectable locally advanced recurrent or metastatic disease, Eastern Cooperative Oncology Group-performance status (ECOG-PS) < 2, and being eligible for DCF. Patients receive either 6 cycles of standard DCF or 8 cycles of modified DCF depending on age (> vs. <= 75 years-old) and ECOG-PS (0 vs. 1). The trial was set up based on a Simon's optimal two-stage design for phase II trials, allowing an early futility interim analysis. The primary endpoint is the observed progression-free survival (PFS) rate at 12 months from the first DCF cycle. A PFS rate below 10% is considered uninteresting, while a PFS rate above 25% is expected. With a unilateral alpha error of 5% and a statistical power of 90%, 66 evaluable patients should be included. Main secondary endpoints are overall survival, PFS, response rate, safety, health-related quality of life, and the correlation of biomarkers with treatment efficacy. Discussion: Since the recommended CF regimen is based in a small retrospective analysis and generates a low rate of complete responses, the Epitopes-HPV02 study will establish a new standard in case of a positive result. Associated biomarker studies will contribute to understand the underlying mechanism of resistance and the role of immunity in SCCA.