Author: Anna Azvolinsky, PhD
A phase II study has demonstrated that combining docetaxel-based chemoradiotherapy and the antibody cetuximab postoperatively in patients with high-risk squamous cell carcinoma of the head and neck led to improved disease-free and overall survival, with no unexpected toxicities. The results of the study were published in the Journal of Clinical Oncology.
Two-hundred and thirty-eight stage III and IV patients were randomized to receive radiation therapy (60 Gy) plus cetuximab and either cisplatin (30 mg/m2) or docetaxel (15 mg/m2) once per week as part of the Radiation Therapy Oncology Group (RTOG) 0234 clinical trial.
The 2-year overall survival (OS) was 69% in the cisplatin treatment arm and 79% in the docetaxel treatment arm. The 2-year disease-free survival (DFS) was 57% and 66% in the cisplatin and docetaxel arms, respectively.
Previously, two large phase III trials, the RTOG 9501 and the European Organisation for Research and Treatment of Cancer (EORTC) 22931 trials, both showed a small but significant survival benefit for postoperative head and neck cancer patients who received adjuvant radiation and chemotherapy concurrently, resulting in the incorporation of cisplatin in an adjuvant regimen for high-risk patients. The drawback was that adding cisplatin to radiation therapy increased toxicity. Many of these patients are not candidates for the combination therapy due to poor performance status, older age, and renal insufficiency. The purpose of the current trial was to test whether combining a molecular therapy such as cetuximab with chemotherapy would improve survival with a better toxicity profile, compared with radiation therapy plus chemotherapy.
After a median follow-up of 4.4 years, 48 patients in the cisplatin arm had a DFS event compared with 51 patients in the docetaxel arm. Cisplatin patients had a 24% reduction (P = .05) and docetaxel patients had a 31% reduction (P = .01) in the DFS failure rate compared with a historical control arm (the RTOG 9501 trial).
Patients who had p16-positive oropharynx tumors (43 of 54 patients) had improved survival compared with those who had p16-negative oropharynx disease.
The most common high-grade non-hematologic adverse events were mucositis, dysphagia, and skin rash, seen in both the cisplatin and docetaxel treatment arms. Patients in the cisplatin arm had a greater frequency of high-grade hematologic toxicities compared with those in the docetaxel arm (27.8% vs 14.2%, respectively). More patients in the docetaxel arm had toxicities deemed unacceptable by those conducting the trial (12.3% in the docetaxel arm vs 9.3% in the cisplatin arm).
Cetuximab is a chimeric human monoclonal antibody against the epidermal growth factor receptor (EGFR).
“The delivery of postoperative chemoradiotherapy (using cisplatin or docetaxel once per week plus 60 Gy radiation) with concurrent once-per-week cetuximab for patients with SCCHN [squamous cell carcinoma of the head and neck] who have high-risk pathologic features is feasible and tolerated with predictable toxicity. The radiation-docetaxel-cetuximab regimen shows particularly promising outcome with improvement in DFS and OS relative to RTOG historical controls and appears worthy of further investigation in high-risk patients with SCCHN,” concluded the authors.
Because the conclusions of this trial rely on a historical control comparison, these results need to be further validated in a phase III control-arm clinical trial. The docetaxel plus cetuximab regimen is currently being tested in a phase II/III clinical trial.
In an editorial, Amanda Psyrri, MD, PhD, and Urania Dafni, MD, both of the University of Athens in Greece, noted that, “In an era when next-generation sequencing is becoming increasingly available, identification of mutations that predict therapeutic response or resistance would be a major advance. Therefore, it seems mandatory that we focus our efforts at identifying an ‘EGFR sensitivity signature.’ Until then, it would seem wise not to conduct large phase III studies with cetuximab in unselected patient populations.”