JERUSALEM, July 21, 2026
Alpha Tau Medical Ltd. announced positive clinical study results evaluating its Alpha DaRT® (Diffusing Alpha-emitters Radiation Therapy) in combination with pembrolizumab (Keytruda®) for elderly patients with locally advanced or metastatic head and neck squamous cell carcinoma (HNSCC). Presented at the American Head and Neck Society (AHNS) 12th International Conference on Head and Neck Cancer in Boston, the study reported a 100% objective response rate (ORR) among all nine evaluable patients, including four complete responses and five partial responses, significantly exceeding the study’s pre-specified Simon two-stage success threshold. The combination therapy also achieved a median overall survival of 18.2 months and median progression-free survival of 5.4 months, outperforming historical pembrolizumab monotherapy benchmarks of 12.3 months overall survival, 3.2 months progression-free survival, and an approximately 19% objective response rate in similar patient populations.
Alpha DaRT Combination Delivers Strong Clinical Activity with Favorable Safety
The prospective, open-label, single-arm study enrolled 11 elderly patients with recurrent unresectable or metastatic HNSCC whose tumors expressed PD-L1 CPS ≥1. Patients first received pembrolizumab, followed by implantation of Alpha DaRT radioactive sources into a target lesion before continuing standard pembrolizumab therapy. Of the 11 enrolled patients, nine were evaluable for response, while two patients died before formal assessment due to unrelated causes. Every evaluable patient demonstrated a measurable systemic tumor response, enabling the study to conclude early after successfully meeting its adaptive design efficacy criteria. Importantly, no Alpha DaRT-related serious adverse events were reported, with only two mild Grade 1 treatment-related adverse events observed across the study, highlighting the therapy’s encouraging safety profile alongside checkpoint inhibitor treatment.
Results Strengthen Alpha Tau’s Immunotherapy Combination Strategy
The encouraging findings further validate Alpha Tau’s strategy of combining localized alpha-radiation therapy with immune checkpoint inhibitors to improve outcomes in difficult-to-treat cancers. Company leadership noted that preclinical research has suggested Alpha DaRT may stimulate systemic anti-tumor immune responses, potentially enhancing the effectiveness of immunotherapy beyond locally treated tumors. Based on the favorable efficacy and safety results, Alpha Tau is continuing discussions with the U.S. FDA regarding a larger clinical study in the United States to further evaluate the combination approach. Investigators also emphasized that elderly patients with recurrent or metastatic head and neck cancer often cannot tolerate chemotherapy, making an effective chemotherapy-free combination particularly valuable.
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Alpha DaRT Platform Continues Expansion Across Multiple Solid Tumors
The latest clinical results build upon previous studies demonstrating strong activity of Alpha DaRT monotherapy in head and neck cancers and reinforce the company’s broader development pipeline. Alpha Tau is actively evaluating the technology across multiple solid tumors, including skin cancer, pancreatic cancer, prostate cancer, and brain tumors, while investigating its potential synergy with immunotherapies. The company believes the combination of Alpha DaRT and pembrolizumab could represent a meaningful advancement for patients with recurrent or metastatic head and neck squamous cell carcinoma, supporting future larger controlled studies designed to confirm survival benefits and expand the platform into additional oncology indications
Source: Alpha Tau press release
