Purpose: To determine the prognostic importance of p16 and human papillomavirus (HPV) in patients with oropharyngeal cancer treated on a phase III concurrent chemoradiotherapy trial. Patients and Methods: Patients with stage III or IV head and neck squamous cell cancer were randomly assigned to concurrent radiotherapy and cisplatin with or without tirapazamine. In this substudy, analyses were restricted to patients with oropharyngeal cancer. p16 was detected by immunohistochemistry, and HPV was detected by in situ hybridization and polymerase chain reaction. Results: Slides were available for p16 assay in 206 of 465 patients, of which 185 were eligible, and p16 and HPV were evaluable in 172 patients. One hundred six (57%) of 185 were p16-positive, and in patients evaluable for both p16 and HPV, 88 (86%) of 102 p16-positive patients were also HPV-positive. Patients who were p16-positive had lower T and higher N categories and better Eastern Cooperative Oncology Group (ECOG) performance status. p16-positive tumors compared with p16-negative tumors were associated with better 2-year overall survival (91% v 74%; hazard ratio [HR], 0.36; 95% CI, 0.17 to 0.74; P = .004) and failure-free survival (87% v 72%; HR, 0.39; 95% CI, 0.20 to 0.74; P = .003). p16 was a significant prognostic factor on multivariable analysis (HR, 0.45; 95% CI, 0.21 to 0.96; P = .04). p16-positive patients had lower rates of locoregional failure and deaths due to other causes. There was a trend favoring the tirapazamine arm for improved locoregional control in p16-negative patients (HR, 0.33; 95% CI, 0.09 to 1.24; P = .13). Conclusion: HPV-associated oropharyngeal cancer is a distinct entity with a favorable prognosis compared with HPV-negative oropharyngeal cancer when treated with cisplatin-based chemoradiotherapy.

Purpose: To determine the association between tumor hypoxia, treatment regimen, and locoregional failure (LRF) in patients with stage III or IV squamous cell carcinoma of the head and neck randomly assigned to radiotherapy (70 Gy in 35 fractions over 7 weeks) plus either tirapazamine and cisplatin in weeks 1, 4, and 7 and tirapazamine alone in weeks 2 and 3 (TPZ/CIS) or cisplatin and infusional fluorouracil during weeks 6 and 7 (chemoboost). Patients and Methods: Forty-five patients were enrolled onto a hypoxic imaging substudy of a larger randomized trial. Pretreatment and midtreatment [¹⁸F]-fluoromisonidazole positron emission tomography scans (FMISO-PET) were performed 2 hours after tracer administration, with qualitative scoring of uptake in both primary tumors and nodes. Results: Thirty-two patients (71%) had detectable hypoxia in either or both primary and nodal disease. In patients who received chemoboost, one of 10 patients without hypoxia had LRF compared with eight of 13 patients with hypoxia; the risk of LRF was significantly higher in hypoxic patients (exact log-rank, P = .038; hazard ratio [HR] = 7.1). By contrast, in patients who received the TPZ/CIS regimen, only one of 19 patients with hypoxic tumors had LRF; risk of LRF was significantly higher in chemoboost patients (P = .001; HR = 15). Similarly, looking at the primary site alone, in patients with hypoxic primaries, zero of eight patients treated with TPZ/CIS experienced failure locally compared with six of nine patients treated with chemoboost (P = .011; HR = 0). Conclusion: Hypoxia on FMISO-PET imaging, in patients receiving a nontirapazamine-containing chemoradiotherapy regimen, is associated with a high risk of LRF. Our data provide the first clinical evidence to support the experimental observation that tirapazamine acts by specifically targeting hypoxic tumor cells.

Purpose: Promising results in a randomized phase II trial with the hypoxic cytotoxin tirapazamine (TPZ) combined with cisplatin (CIS) and radiation led to this phase III trial. Patients and Methods: Patients with previously untreated stage III or IV (excluding T1-2N1 and M1) squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx were randomly assigned to receive definitive radiotherapy (70 Gy in 7 weeks) concurrently with either CIS (100 mg/m²) on day 1 of weeks 1, 4, and 7 or CIS (75 mg/m²) plus TPZ (290 mg/m²/d) on day 1 of weeks 1, 4, and 7 and TPZ alone (160 mg/m²/d) on days 1, 3, and 5 of weeks 2 and 3 (TPZ/CIS). The primary end point was overall survival (OS). The planned sample size was 850, estimated to result in 334 deaths, which would provide 90% power to detect a difference in 2-year survival rates of 60% v 70% for CIS versus TPZ/CIS, respectively (hazard ratio = 0.69). Results: Eight hundred sixty-one patients were accrued from 89 sites in 16 countries. In an intent-to-treat analysis, the 2-year OS rates were 65.7% for CIS and 66.2% for TPZ/CIS (TPZ/CIS – CIS: 95% CI, −5.9% to 6.9%). There were no significant differences in failure-free survival, time to locoregional failure, or quality of life as measured by Functional Assessment of Cancer Therapy–Head and Neck. Conclusions: We found no evidence that the addition of TPZ to chemoradiotherapy, in patients with advanced head and neck cancer not selected for the presence of hypoxia, improves OS.

Purpose: To select one of two chemoradiotherapy regimens for locally advanced squamous cell carcinoma (SCC) of the head and neck as the experimental arm for the next Trans-Tasman Radiation Oncology Group phase III trial. Patients and Methods: One hundred twenty-two previously untreated patients with stage III/IV SCC of the head and neck were randomized to receive definitive radiotherapy (70 Gy in 7 weeks) concurrently with either cisplatin (75 mg/m²) plus tirapazamine (290 mg/m²/d) on day 2 of weeks 1, 4, and 7, and tirapazamine alone (160 mg/m²/d) on days 1, 3, and 5 of weeks 2 and 3 (TPZ/CIS), or cisplatin (50 mg/m²) on day 1 and infusional fluorouracil (360 mg/m²/d) on days 1 through 5 of weeks 6 and 7 (chemoboost). Results: Three-year failure-free survival rates were 55% with TPZ/CIS (95% CI, 39% to 70%) and 44% with chemoboost (95% CI, 30% to 60%; log-rank P = .16). Three-year locoregional failure-free rates were 84% in the TPZ/CIS arm (95% CI, 71% to 92%) and 66% in the chemoboost arm (95% CI, 51% to 79%; P = .069). More febrile neutropenia and grade 3 or 4 late mucous membrane toxicity were observed with TPZ/CIS, while acute skin radiation reaction was more severe and prolonged with chemoboost. Compliance with protocol treatment was satisfactory on both arms. Conclusion: Both regimens are feasible and are associated with significant but acceptable toxicity profiles in the cooperative group setting. Based on the promising efficacy seen in this trial, TPZ/CIS is being evaluated in a large phase III trial.

Background Cemiplimab, a high-affinity, potent human immunoglobulin G4 monoclonal antibody to programmed cell death-1 demonstrated antitumor activity in a Phase 1 advanced cutaneous squamous cell carcinoma (CSCC) expansion cohort (NCT02383212) and the pivotal Phase 2 study (NCT02760498). Here we report the primary analysis of fixed dose cemiplimab 350 mg intravenously every 3 weeks (Q3W) (Group 3) and provide a longer-term update after the primary analysis of weight-based cemiplimab 3 mg/kg intravenously every 2 weeks (Q2W) (Group 1) among metastatic CSCC (mCSCC) patients in the pivotal study (NCT02760498). Methods The primary objective for each group was objective response rate (ORR) per independent central review (ICR). Secondary endpoints included ORR by investigator review (INV), duration of response (DOR) per ICR and INV, and safety and tolerability. Results For Group 3 (n=56) and Group 1 (n=59), median follow-up was 8.1 (range, 0.6 to 14.1) and 16.5 (range, 1.1 to 26.6) months, respectively. ORR per ICR was 41.1% (95% CI, 28.1% to 55.0%) in Group 3, 49.2% (95% CI, 35.9% to 62.5%) in Group 1, and 45.2% (95% CI, 35.9% to 54.8%) in both groups combined. Per ICR, Kaplan–Meier estimate for DOR at 8 months was 95.0% (95% CI, 69.5% to 99. 3%) in responding patients in Group 3, and at 12 months was 88.9% (95% CI, 69.3% to 96.3%) in responding patients in Group 1. Per INV, ORR was 51.8% (95% CI, 38.0% to 65.3%) in Group 3, 49.2% (95% CI, 35.9% to 62.5%) in Group 1, and 50.4% (95% CI, 41.0% to 59.9%) in both groups combined. Overall, the most common adverse events regardless of attribution were fatigue (27.0%) and diarrhea (23.5%). Conclusion In patients with mCSCC, cemiplimab 350 mg intravenously Q3W produced substantial antitumor activity with durable response and an acceptable safety profile. Follow-up data of cemiplimab 3 mg/kg intravenously Q2W demonstrate ongoing durability of responses. Trial registration number Clinicaltrials.gov, NCT02760498. Registered May 3, 2016, https://clinicaltrials.gov/ct2/show/NCT02760498