Trial results for the study NCT03386357 investigating pembrolizumab with radiotherapy in metastatic head and neck squamous cell carcinoma (HNSCC) were posted on ClinicalTrials.gov on 2026-03-12. The study found that the combination of pembrolizumab and radiotherapy showed an Odds Ratio of 2.43 (p=0.033) for best response compared to pembrolizumab alone.
Background
Pembrolizumab (Keytruda) is an immunotherapy drug. This Phase 2 study explored its use in combination with radiotherapy for patients with metastatic head and neck squamous cell carcinoma (HNSCC) in the second-line therapy setting.
Trial design
The study NCT03386357 was a Phase 2, randomized trial that enrolled 115 participants. It investigated the use of pembrolizumab with radiotherapy in patients with metastatic head and neck squamous cell carcinoma. The trial compared two intervention arms: pembrolizumab combined with radiotherapy (Group A) versus pembrolizumab alone (Group B). The study was terminated.
Key results
The trial evaluated "Best Response According to iRECIST Criteria" in both study arms.
- For Group A (Pembrolizumab+RT), the counts of participants for this outcome were: 6, 14, 9, 5, 10, 0.
- For Group B (Pembrolizumab alone), the counts were: 3, 10, 10, 10, 10, 3.
A Fisher Exact analysis for best response showed an Odds Ratio (OR) of 2.43 (95.0% CI: 1.19 to null) with a p-value of 0.033, indicating a statistically significant difference favoring the combination arm. Another Fisher Exact analysis yielded a p-value of 0.19.
Additionally, Log Rank analyses were performed for Hazard Ratios. One analysis reported a Hazard Ratio (HR) of 0.96 (95.0% CI: 0.64 to 1.43) with a p-value of 0.9. Another Log Rank analysis showed an HR of 1.04 (95.0% CI: 0.67 to 1.63) with a p-value of 0.84.
What this means
The statistically significant Odds Ratio of 2.43 (p=0.033) for best response suggests that combining pembrolizumab with radiotherapy may improve treatment response in patients with metastatic head and neck squamous cell carcinoma compared to pembrolizumab monotherapy. While this Phase 2 trial was terminated, these results provide initial evidence for the potential benefit of this combination strategy. The non-significant findings from other analyses indicate that further research would be needed to fully understand the broader impact on patient outcomes like survival.
Source
The information for these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for study NCT03386357, titled "Radiotherapy With Pembrolizumab in Metastatic Head and Neck Squamous Cell Carcinoma (HNSCC)," were posted on 2026-03-12 on clinicaltrials.gov.