On July 21, 2026 Alpha Tau Medical Ltd. ("Alpha Tau" or the "Company") (Nasdaq: DRTS, DRTSW), the developer of the innovative alpha-radiation cancer therapy Alpha DaRT, reported positive results from a clinical study evaluating Alpha DaRT in combination with pembrolizumab (Keytruda) in elderly patients with locally advanced and metastatic head and neck squamous cell carcinoma (HNSCC), in which the combination produced a 100% objective response rate and a median overall survival of 18.2 months among evaluable patients. The results are being presented in a podium presentation at the American Head and Neck Society ("AHNS") 12th International Conference on Head and Neck Cancer, held July 18-22, 2026, in Boston, Massachusetts.
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Head and neck cancer is among the most common cancers worldwide, with an estimated 890,000 new cases diagnosed globally each year, and with more than 60,000 new cases of HNSCC estimated in the United States in 2026 across the oral cavity, pharynx, and larynx. Despite treatment with curative intent, roughly half of patients with HNSCC will experience recurrence, and distant spread, when it occurs, most often involves the lung.
Since the Keytruda KEYNOTE-048 trial, pembrolizumab, with or without chemotherapy, has been the first-line standard of care for recurrent or metastatic HNSCC; however, as monotherapy in patients whose tumors express PD-L1 (Combined Positive Score, or CPS, ≥1), pembrolizumab was observed in the KEYNOTE-048 trial to produce a median overall survival of 12.3 months and an objective response rate of approximately 19%, leaving considerable room for improvement, particularly for elderly and frail patients who may not tolerate the addition of chemotherapy.
Alpha Tau’s study is a single-center, prospective, open-label, single-arm study evaluating Alpha DaRT in combination with pembrolizumab in up to 48 patients with recurrent unresectable or metastatic HNSCC and PD-L1 CPS ≥1, using a Simon two-stage adaptive design. Patients received a lead-in dose of pembrolizumab, followed by insertion of Alpha DaRT sources into a target lesion; the sources were removed ~14 days later, and patients continued on pembrolizumab per standard dosing. Tumor response was assessed systemically, i.e., in all tumors, both treated and untreated by Alpha DaRT, using Response Evaluation Criteria in Solid Tumors (RECIST v1.1), and safety was graded using the Common Terminology Criteria for Adverse Events (CTCAE v5.0). Eleven patients (four female, seven male) were recruited in total, with a mean age of 72 years (range 52-96). Two patients died prior to response evaluation, leaving nine patients evaluable for response; one died before Alpha DaRT treatment, and the other died shortly after treatment from an unrelated cardiovascular issue. With every evaluable patient responding, the trial reached the efficacy threshold built into its two-stage adaptive design, under which the study was permitted to stop for success once more than six patients responded, and enrollment was concluded on that basis.
Efficacy Results
Note: Caution should be exercised in comparing results from unrelated clinical studies due to differences in study designs, patient populations and other relevant factors.
Response Rate
Among evaluable patients, treatment with Alpha DaRT plus pembrolizumab produced an objective response rate (i.e., systemic complete response plus partial response) of 100%, including four complete responses and five partial responses, for a complete response rate of 44%. By comparison, pembrolizumab monotherapy in the PD-L1 CPS ≥1 population of KEYNOTE-048 produced an objective response rate of approximately 19%.
Survival Data
Median overall survival was 18.2 months, and median progression-free survival was 5.4 months, with four patients remaining alive at the time of this analysis. By comparison, pembrolizumab monotherapy in a similar population in the KEYNOTE-048 trial achieved a median overall survival of 12.3 months and a median progression-free survival of approximately 3.2 months.
Safety Results
No Alpha DaRT-related serious adverse events were observed. Only two Alpha DaRT-related adverse events were reported across the treated cohort, both Grade 1 in severity.
Uzi Sofer, CEO of Alpha Tau, stated: "These results reinforce two priorities at the heart of our strategy: establishing Alpha DaRT in localized, unresectable disease, and building the combination evidence to compete in the metastatic setting alongside blockbuster checkpoint inhibitors. Our interim data had already shown us that response rates with Alpha DaRT plus pembrolizumab were exceptionally high; what we were waiting for was the survival follow-up to confirm those responses would translate into real, lasting benefit. Now that the data have matured, the picture is even stronger. Combination trials like this one are central to how we intend to grow the platform. Showing that Alpha DaRT can be added to a systemic backbone safely, and with results like these, is exactly the kind of evidence we hope will define its role across our pipeline. And we won’t stop here: We are exploring, in ongoing discussion with the FDA, the possibility of a similar but larger study in the U.S."
Prof. Aron Popovtzer, MD, Director of the Sharett Institute of Oncology at Hadassah University Medical Center and the lead Principal Investigator in this clinical study at Hadassah, commented: "Elderly patients with recurrent or metastatic head and neck squamous cell carcinoma are among the most difficult we treat. Since KEYNOTE-048, pembrolizumab has been our first-line standard of care, but as a single agent it produces a response in fewer than one in five patients, and many are too frail to add chemotherapy. That unmet need is what led us to design the first study to combine Alpha DaRT with checkpoint inhibition, adding a localized, immune-activating alpha-emitting radiotherapy to the systemic treatment these patients are already receiving. After years of work, it is deeply gratifying to see the effort was worth it – the results are genuinely encouraging, and they exceeded our expectations. Every evaluable patient responded, including several complete responses, with improvements in both overall and progression-free survival relative to historic data on pembrolizumab alone and a safety profile that let patients stay on their standard treatment. To my knowledge, no other combination study with pembrolizumab has shown results like these in this patient population, and it is a real achievement to see a therapy add this much value on top of a checkpoint inhibitor. These are early data, and larger controlled studies are needed to confirm the benefit, but they make a compelling case for continuing to investigate Alpha DaRT with immunotherapy, both in head and neck cancer and across other solid tumors."
Robert Den, MD, Chief Medical Officer of Alpha Tau, added: "It’s worth reading these results against the bigger picture of where our global clinical trial pipeline is heading. We have strong preclinical data suggesting that Alpha DaRT may prime a systemic anti-tumor immune response, and we have clinical experience, including multiple studies in head and neck and skin cancer, showing that Alpha DaRT monotherapy carries a favorable safety profile in this population. What this study suggests is that combining Alpha DaRT with pembrolizumab can translate that immune-priming effect into a clinical survival benefit for patients with recurrent or metastatic head and neck cancer. These results reinforce our plan to validate the clinical benefit of Alpha DaRT in this patient population in larger studies, and they add another key data point to a pipeline that now spans head and neck, skin, pancreatic, prostate, and brain cancers, among others."
About the Study
The study builds on Alpha Tau’s foundation of Alpha DaRT monotherapy data in head and neck and skin cancer, including a first-in-human study in which Alpha DaRT achieved an objective response rate of 100% and a complete response rate of 78.6% among evaluable SCC lesions in a population that skewed toward elderly, heavily pre-treated and radioresistant patients. The current study pairs Alpha DaRT with pembrolizumab, the current first-line standard of care for CPS ≥1 recurrent or metastatic HNSCC, to evaluate whether adding a localized, immune-activating radiotherapeutic to systemic checkpoint inhibition can improve outcomes without the added toxicity associated with chemotherapy. The study was conducted at Hadassah University Medical Center in Jerusalem, Israel. For more information, please see View Source
(Press release, Alpha Tau Medical, JUL 21, 2026, View Source [SID1234669337])