Radiotherapy-Dose Escalated for Large Volume Primary Tumors-And Cetuximab with or without Induction Chemotherapy for HPV Associated Squamous Cell Carcinoma of the Head and Neck-A Randomized Phase II Trial.

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Eligible patients in this multicenter, randomized, controlled, phase 2 trial had p16-positive locoregionally advanced SCCHN. Patients were randomized in a 1:1 ratio to either RT with cetuximab (arm B) versus the same regimen preceded by two cycles of taxotere/cisplatin/5-FU (arm A). The RT dose was escalated to 74.8 Gy for large volume primary tumors. Eligibility criteria included patients of 18-75 years, an ECOG performance status 0-1, and adequate organ functions. From January 2011 to February 2016, 152 patients, all with oropharyngeal tumors were enrolled, 77 in arm A and 75 in arm B. Two patients, one in each group, withdrew their consent after randomization, leaving 150 patients for the ITT analysis. PFS at 2 years was 84.2% (95% CI 76.4-92.8) in arm A and 78.4% (95% CI 69.5-88.3) in arm B (HR 1.39, 95% CI 0.69-2.79, p = 0.40). At the time of analysis, there were 26 disease failures, 9 in arm A and 17 in arm B. In arm A, 3 patients had local, 2 regional, and 4 distant relapses as first sites of recurrence, and in arm B, 4, 4, and 9 relapses in corresponding sites. Eight out of 26 patients with disease progression had salvage therapy and 7 were alive NED (no evidence of disease), at 2 years. Locoregional control was 96% in arm A and 97.3% in arm B and OS 93% and 90.5%, respectively. Local failure as first site of recurrence was low, in 4.6% of patients and was similar for T1/T2 and T3/T4 tumors (n.s). Nevertheless, out of 7 patients with primary local failures, 4 were treated with the escalated RT dose. Toxicity was low and similar in the treatment arms. There was one fatal event in arm A where the combined effects of the drugs used in chemotherapy and cetuximab could not be ruled out. PFS, locoregional control and toxicity did not differ between the two arms, OS was high, and there were few local relapses. In arm B, more than twice as many patients had distant metastasis as the first site of relapse compared to arm A. The response to IC was found to define 29% of patients in arm A who did not have a tumor relapse during follow-up. An escalated dose of 74.8 Gy could mitigate the negative impact of large tumor volume but for some patients, even this intensified treatment was insufficient.