Importance: The Canadian Cancer Trials Group study HN.6 is the largest randomized clinical trial to date comparing the concurrent administration of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies with radiotherapy (RT) to standard chemoradiotherapy in locoregionally advanced squamous cell carcinoma of the head and neck (LA-SCCHN).

Objective: To compare progression-free survival (PFS) in patients with LA-SCCHN treated with standard-fractionation RT plus high-dose cisplatin vs accelerated-fractionation RT plus the anti-EGFR antibody panitumumab. Design, Setting, and

Participants: A randomized phase 3 clinical trial in 17 Canadian centers. A total of 320 patients were randomized between December 2008 and November 2011. Interventions: Patients with TanyN+M0 or T3-4N0M0 LA-SCCHN were randomized 1:1 to receive standard-fractionation RT (70 Gy/35 over 7 weeks) plus cisplatin at 100 mg/m2 intravenous for 3 doses (arm A) vs accelerated-fractionation RT (70 Gy/35 over 6 weeks) plus panitumumab at 9 mg/kg intravenous for 3 doses (arm B). Main Outcomes and

Measures: Primary end point was PFS. Due to an observed declining event rate, the protocol was amended to a time-based analysis. Secondary end points included overall survival, local and regional PFS, distant metastasis-free survival, quality of life, adverse events, and safety.

Results: Of 320 patients randomized (268 [84%] male; median age, 56 years), 156 received arm A and 159 arm B. A total of 93 PFS events occurred. By intention-to-treat, 2-year PFS was 73% (95% CI, 65%-79%) in arm A and 76% (95% CI, 68%-82%) in arm B (hazard ratio [HR], 0.95; 95% CI, 0.60-1.50; P = .83). The upper bound of the HR 95% CI exceeded the prespecified noninferiority margin. Two-year overall survival was 85% (95% CI, 78%-90%) in arm A and 88% (95% CI, 82%-92%) in arm B (HR, 0.89; 95% CI, 0.54-1.48; P = .66). Incidence of any grade 3 to 5 nonhematologic adverse event was 88% in arm A and 92% in arm B (P = .25). Conclusions and

Relevance: With a median follow-up of 46 months, the PFS of panitumumab plus accelerated-fractionation RT was not superior to cisplatin plus standard-fractionation RT in LA-SCCHN and noninferiority was not proven. Despite having negative results, HN.6 has contributed important data regarding disease control and toxic effects of these treatment strategies.

Trial Registration: clinicaltrials.gov Identifier: NCT00820248.