Alpha Tau Announces New Positive Interim Results from its U.S. Alpha DaRT® Recurrent Glioblastoma Trial: All Patients Treated are Alive with Median Survival Not Reached, 6.9 Months Median Follow-Up in the First Six Evaluable Patients With 100% ORR, 100%

- All eight treated brain cancer patients in the trial remain alive as of November 11, 2026; median overall survival has not been reached, with a median follow-up of 6.9 months from trial enrollment (range 3.1 to 11.6 months) in the six patients who have reached response assessment -

- All six patients who have reached response assessment achieved a RANO objective response as their best overall response, with five patients showing complete responses (83.3%), including a previously reported stable disease, and one patient with a partial response (16.7%) with a 58% decrease in tumor measurements -

- Primary endpoints of feasibility and safety: planned Alpha DaRT sources were successfully deployed in all eight patients treated to date (100%), with no unanticipated serious adverse events (SAEs) -

- Follow-up scans in several of the patients show asymptomatic radiation necrosis, a known effect of focal radiation in previously irradiated brain tissue; whether these findings suggest necrosis or tumor recurrence is expected to become clearer with additional follow-up over the coming months -

- No definitive local recurrence observed in any treated patient -

- According to the National Brain Tumor Society, glioblastoma is one of the most complex, deadly, and treatment-resistant cancers, with an estimated average survival rate of only 8 months -

- Conference call with principal investigator and the Company to be held tomorrow, Monday, November 16, 2026, at 8:30am ET -

JERUSALEM, Nov. 15, 2026 (GLOBE NEWSWIRE) -- Alpha Tau Medical Ltd. (Nasdaq/TASE: DRTS, DRTSW) (“Alpha Tau” or the “Company”), the developer of the innovative alpha-radiation cancer therapy Alpha DaRT®, today announced updated interim results from its U.S. REGAIN (Recurrent Glioblastoma Alpha DaRT Intratumoral Therapy) trial of Alpha DaRT for patients with recurrent glioblastoma (GBM). The results, measured as of November 11, 2026, were presented in a poster titled “First-In-Human Study to Assess the Feasibility and Safety of Intratumoral Diffusing Alpha Emitters for the Treatment of Recurrent Glioblastoma: Interim Analysis (REGAIN)” at the 31st Annual Meeting of the Society for Neuro-Oncology (SNO), held November 12-15, 2026, in Philadelphia, by the study investigator Team from The Ohio State University Comprehensive Cancer Center (OSUCCC - James). Eight patients have been treated in the trial to date, six of whom have reached response assessment.

Uzi Sofer, CEO of Alpha Tau, commented: “In May we shared the first three patients treated with Alpha DaRT in the brain. Six months later, we see how truly transformational Alpha DaRT could be for recurrent GBM. Eight patients have been treated, every procedure has gone as planned, and every one of those patients is alive. The trial thus far has exceeded our wildest expectations, particularly in such a difficult cancer. Glioblastoma is one of the most devastating diagnoses in oncology, and recurrence is virtually inevitable. We look forward to following these patients’ progress as their scans mature, and to continuing enrollment toward 20 patients, which we believe, based on initial discussions, may support market submission requirements for Alpha DaRT in patients with this disease.”

Primary endpoints: Feasibility and Safety

The primary endpoints of the REGAIN trial are feasibility and safety. Planned Alpha DaRT sources were successfully deployed in all eight patients treated to date (100%). No unanticipated SAEs have been observed to date. One grade 3 SAE, previously reported in May 2026, was a seizure with Todd’s paralysis (a temporary paralysis following a seizure) that occurred in a patient with a prior history of seizures; it required a 48-hour hospital stay and resolved with steroids. All patients recovered from any adverse events without residual procedure-related symptoms.

Survival

All eight treated patients were alive as of November 11, 2026. Among the six patients who have reached response assessment, the median follow-up from trial enrollment was 6.9 months (range 3.1 to 11.6 months), and median overall survival has not been reached. Three of these patients have now been followed for more than eight months from enrollment.

Tumor Response

The six evaluable patients have reached response assessment by MRI. Measured as best overall response and using RANO criteria, all six patients (100%) achieved an objective response: five patients (83.3%) achieved a complete response, with no measurable tumor remaining at the treated site, and one patient (16.7%) achieved a partial response, with a 58% decrease in tumor measurements. The first three patients, whose initial results the Company reported in May 2026 as two complete responses and one stable disease, have all now been assessed as confirmed complete responses, the third patient having converted from stable disease to complete response upon longer follow-up. The responses in the three most recently assessed patients were observed at their early assessments and remain subject to confirmation on subsequent scans. No definitive recurrence within the treated area has been reported in any patient as of the cutoff date. One patient, the first patient treated, developed tumor progression away from the treated area approximately nine months after treatment while remaining free of recurrence in the area treated, and has received additional therapy.

Follow-up imaging has shown necrosis or suspected necrosis in or around the treated area in four of the six patients who have reached response assessment, which is a known effect of focal radiation, particularly in brain tissue that has previously been irradiated. The necrosis observed to date has been asymptomatic, and none of these findings was a serious adverse event. In two of these patients, the most recent scans, approximately three months after treatment, also showed new or increased enhancement adjacent to or outside the treated area, and the investigators cannot yet determine whether these findings represent necrosis or tumor progression. These patients are being evaluated with additional imaging and, as needed, biopsy. The Company expects the picture to become clearer over the coming months as additional scans are obtained, and the recurrence data reported today may change as a result.

The patients were treated at OSUCCC - James in Columbus, Ohio, by a multidisciplinary Team led by Principal Investigator and Radiation Oncologist Joshua D. Palmer, MD, Medical Physicist Michael Degnan, MS, DABR and Neurosurgeon J. Bradley Elder, MD, using a novel stereotactic delivery approach designed specifically by Alpha Tau for intracranial use, through minimally invasive burr-hole access without open craniotomy. The REGAIN trial is designed to enroll up to 20 patients, and enrollment and follow-up are ongoing.

Dr. Joshua Palmer, Principal Investigator and Radiation Oncologist at the OSUCCC - James, commented: “I am even more encouraged by this newer set of interim results from the REGAIN trial, because we are now beginning to see survival. In recurrent glioblastoma, every patient who reaches six, nine and twelve months makes the picture more compelling, and all of our patients are alive. We have seen responses in every patient who has reached assessment, and have seen no definitive tumor regrowth in the area we treated. We are excited to continue to follow along these patients’ treatment journeys and to treat additional patients in the coming months.”

Dr. Robert Den, Chief Medical Officer of Alpha Tau, added: “The primary endpoints of this trial are feasibility and safety, and on both the data are consistent across all eight patients: every treatment was done as planned, and there have been no unanticipated serious adverse events. The response and survival data are incredibly encouraging for such a difficult disease, and longer follow-up will continue to be of interest in understanding the durability of these responses as we continue to enroll the study.”

Conference Call on Monday, November 16, 2026 at 8:30am ET

Alpha Tau will host a conference call with management, together with Dr. Joshua Palmer, on November 16, 2026, at 8:30 am ET.

To access the call, please register at https://alpha-dart-rgbm-at-sno-26.open-exchange.net/. An archived webcast will be available on the Company’s website following the event.

About the REGAIN Study

The REGAIN study is a prospective, open-label, single arm interventional study designed to evaluate the feasibility and safety of Alpha DaRT for the potential treatment of recurrent glioblastoma. The clinical trial is expected to enroll up to 20 U.S. patients with recurrent glioblastoma not amenable to surgical resection who have undergone a prior course of central nervous system radiation. The primary objective of the study is to evaluate the feasibility and safety of the treatment, following the Company’s promising results from pre-clinical studies. Additional information about the trial can be found at https://www.clinicaltrials.gov/study/NCT06910306

About Alpha Tau Medical Ltd.

Founded in 2016, Alpha Tau is an Israeli oncology therapeutics company focused on the research, development, and potential commercialization of the Alpha DaRT for the treatment of solid tumors. The technology was initially developed by Prof. Itzhak Kelson and Prof. Yona Keisari from Tel Aviv University.

About Alpha DaRT®

Alpha DaRT (Diffusing Alpha-emitters Radiation Therapy) is designed to enable highly potent and conformal alpha-irradiation of solid tumors by intratumoral delivery of radium-224 impregnated sources. When the radium decays, its short-lived daughters are released from the sources and disperse while emitting high-energy alpha particles with the goal of destroying the tumor. Since the alpha-emitting atoms diffuse only a short distance, Alpha DaRT aims to primarily affect the tumor and to spare healthy tissue surrounding it. For intracranial use, Alpha DaRT sources are delivered via a specialized stereotactic delivery system that interfaces with standard real-time neuronavigation platforms, with the goal of precise, image-guided source placement through minimally invasive burr-hole access without requiring open craniotomy.

Forward-Looking Statements

This press release includes “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. When used herein, words including “anticipate,” “will,” “plan,” “may,” “continue,” and similar expressions are intended to identify forward-looking statements. Other than its marketing approval in Japan for unresectable locally advanced or locally recurrent head and neck cancer and in Israel for products intended to treat Squamous Cell Carcinoma (SCC) of the Skin and Oral Cavity, the Alpha DaRT treatment has not been approved for commercialization or for use outside of an approved clinical trial. In addition, any statements or information that refer to the Alpha DaRT treatment in glioblastoma patients, including the interim results described herein and their interpretation, the confirmation of responses and the evaluation of imaging findings on subsequent scans, the expected enrollment and conduct of the REGAIN trial, the potential benefits and associated risks, safety, feasibility and efficacy, durability of responses, future applications and uses, and other expectations, beliefs and plans, including with respect to clinical trials, regulatory approvals and studies, are forward-looking. All forward-looking statements are based upon Alpha Tau’s current expectations and various assumptions. Alpha Tau believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. Alpha Tau may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various important factors, including, without limitation: (i) Alpha Tau’s ability to receive regulatory approval for its Alpha DaRT technology or any future products or product candidates; (ii) Alpha Tau’s limited operating history; (iii) Alpha Tau’s incurrence of significant losses to date; (iv) Alpha Tau’s need for additional funding and ability to raise capital when needed; (v) Alpha Tau’s limited experience in medical device discovery and development; (vi) Alpha Tau’s dependence on the success and commercialization of the Alpha DaRT technology; (vii) the failure of preliminary data from Alpha Tau’s clinical studies to predict final study results; (viii) failure of Alpha Tau’s early clinical studies or preclinical studies to predict future clinical studies; (ix) Alpha Tau’s ability to enroll patients in its clinical trials; (x) undesirable side effects caused by Alpha Tau’s Alpha DaRT technology or any future products or product candidates; (xi) Alpha Tau’s exposure to patent infringement lawsuits; (xii) Alpha Tau’s ability to comply with the extensive regulations applicable to it; (xiii) the ability to meet Nasdaq’s listing standards; (xiv) costs related to being a public company; (xv) changes in applicable laws or regulations; and the other important factors discussed under the caption “Risk Factors” in Alpha Tau’s annual report filed on Form 20-F with the SEC on March 9, 2026, and other filings that Alpha Tau may make with the United States Securities and Exchange Commission. These and other important factors could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While Alpha Tau may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause its views to change. These forward-looking statements should not be relied upon as representing Alpha Tau’s views as of any date subsequent to the date of this press release.

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