Clinical Trial Results

NRG-HN004, a Phase 2/3, randomized, open-label study sponsored by the National Cancer Institute (NCI), involved patients with locally or regionally advanced squamous cell carcinoma of the head and neck who were not eligible for cisplatin. A total of 190 patients were enrolled, including a safety lead-in cohort, and 186 were randomized to receive radiation therapy in combination with either durvalumab (Imfinzi) or cetuximab (Erbitux). Due to the interim analysis showing that durvalumab did not meet the criteria for improvement in progression-free survival (PFS), enrollment was stopped in July 2021, and the study was officially closed in September 2022.

Efficacy Analysis

As of the July 31, 2023 data cutoff, with a median follow-up of 2.3 years, the 2-year PFS rate was 50.6% in the durvalumab arm and 63.7% in the cetuximab arm. The hazard ratio (HR) was 1.33, with a 95% confidence interval of 0.84 to 2.12, and a p-value of 0.89, indicating that durvalumab was not superior to the control arm. The key takeaway is that the strategy of amplifying radiation-induced immune responses through PD-L1 blockade failed to replace the EGFR-targeted combination therapy.

Drug and Safety

Imfinzi, from AstraZeneca (AZN), is an anti-PD-L1 monoclonal antibody that blocks the binding of PD-L1 to PD-1 and CD80. It received its first FDA approval in the United States on May 1, 2017, but does not have an approved indication for head and neck cancer. Erbitux, from Eli Lilly (LLY), is an EGFR-targeted IgG1 monoclonal antibody, and the FDA approved its use in combination with radiation therapy for locally or regionally advanced squamous cell carcinoma of the head and neck on March 1, 2006. Among grade 3 or higher adverse events, dysphagia occurred in 22% of the durvalumab arm and 30% of the cetuximab arm, lymphopenia in 28% and 33%, and mucositis in 11% and 18%, respectively. These results did not demonstrate a safety advantage that could offset the efficacy difference.

Competitive Landscape

In patients who are eligible for treatment, high-dose cisplatin and radiation therapy remain the standard of care for curative intent. For patients who are not eligible for cisplatin due to renal impairment, hearing loss, or neuropathy, cetuximab in combination with radiation therapy is a major alternative. Keytruda (pembrolizumab; PD-1), a competing immune checkpoint inhibitor, also failed to demonstrate improvement in tumor control or survival compared to cetuximab in the Phase 2 PembroRad trial, and Phase 3 KEYNOTE-412 and JAVELIN Head and Neck 100 also showed the limitations of a curative chemoradiation strategy. Therefore, the clinical consistency is reinforced that it is difficult to simply extend the established efficacy of immune checkpoint inhibitors in recurrent or metastatic disease to local, advanced, curative treatment.

Market and Industry Implications

The market for head and neck cancer in the eight major markets is expected to grow from $3.76 billion in 2024 to $7.68 billion in 2034, with a compound annual growth rate of 7.4%. These results reduce the opportunity for durvalumab to expand into new indications, while strengthening the defense of cetuximab, which already has FDA approval and a long track record of use. Future development should focus on biomarker-driven designs that incorporate HPV status, the immune microenvironment, and radiation fractionation, rather than non-selective PD-1/PD-L1 combinations.