Phase II trial of cetuximab and radiation in low risk, HPV positive patients with locally advanced squamous cell carcinoma of the oropharynx (SCCOP).

6084 Background: We designed a single arm phase II trial to determine the efficacy and toxicity of concurrent cetuximab (C) radiotherapy (RT) in patients with low risk SCCOP. Low risk was defined by tumor stage ( < T4, N3), Human Papilloma Virus-16 positive, and < 10 pack year smoking history. Primary endpoint was rate of recurrence.Methods: 38 patients (pts) with stage III/IVA were enrolled. The median age was 58.5 years (range: 44-76), 87 % males, 13% females; 97 % Caucasian; 88% ECOG 0, 12% ECOG 1. All patients received C 400 mg/m2 day (d) 0 then 250 mg/m2 d 7 and weekly during RT. Pts were treated with a planned 70 Gray (Gy) in 35 fractions over 7 weeks to the gross tumor and 50-60 Gy to subclinical target volumes. Results: As of January 2016 with a median follow up of 20.2 months, 38 pts were evaluable. One pt recurred with distant metastases and died 11 months post C-RT. Median PFS and OS have not been reached. Grade 3 treatment related toxicities were seen in 23 pts (60%), no grade 4 toxicities were seen. The most common grade 3 toxicities included mucositis (12 pts), dehydration (5 pts), dysphagia (4 pts), and leukopenia (4 pts). Twelve (32%) patients had at least one dose of C omitted, primarily due to toxicity. Conclusions: Patients with low risk, HPV positive SCCOP, treated with C + RT, achieve excellent control of disease, though the acute toxicity profile appears to be more significant when compared to historical controls with platinum and radiation. Clinical trial information: NCT01663259.