Alpha Tau cleared to complete GBM trial after 100% local disease control

FDA has authorised Alpha Tau to enrol the final seven patients in its REGAIN recurrent glioblastoma trial following encouraging interim data from the first three

The Biotech Times Editorial Team By The Biotech Times Editorial Team
A bright, modern medical imaging room contains a large MRI machine with an attached examination table, a rolling medical cart, wall-mounted whiteboards, and a workstation with a chair, desk, and three monitors facing large windows.

Alpha Tau Medical has received FDA clearance to proceed with full enrolment in its REGAIN trial of Alpha DaRT intratumoral radiotherapy in recurrent glioblastoma, following a pre-specified interim safety review of the first three patients treated. The Jerusalem- and Nasdaq-listed company said it intends to restart recruitment immediately, with the trial now expanded to include two additional US academic cancer centres.

Interim data, cut off on 3 May 2026, showed that all three patients treated between December 2025 and March 2026 at The Ohio State University Comprehensive Cancer Center achieved local disease control. Two of the three met criteria for complete response under RANO (Response Assessment in Neuro-Oncology) definitions, meaning all enhancing tumour lesions had disappeared on serial MRI scans. The third patient showed meaningful tumour volume reduction. One grade 3 serious adverse event was recorded and subsequently resolved; no unanticipated toxicities were observed.

What the data means in context

Recurrent glioblastoma is among the most treatment-resistant indications in oncology. Standard second-line systemic options, including bevacizumab and temozolomide rechallenge, typically produce objective response rates in the low single digits, and median survival after recurrence is measured in months rather than years. Against that backdrop, a 67% complete response rate in three patients is a striking signal, though the sample size is small and the open-label, single-arm design means the results cannot be benchmarked against a control group. Alpha Tau's chief medical officer, Dr Robert Den, acknowledged the pattern while tempering expectations, describing it as "the kind of consistent, interpretable signal that gives us confidence as we advance to the next set of patients."

The REGAIN study is a ten-patient feasibility and safety trial and is not powered for efficacy. Investors and clinicians will need to wait for the complete dataset, including longer follow-up, before drawing conclusions about durability of response or overall survival benefit.

Regulatory trajectory and competitive landscape

Alpha Tau has accumulated a series of regulatory recognitions in this indication. The FDA granted Breakthrough Device Designation for Alpha DaRT in recurrent glioblastoma in October 2021, and in October 2024 the company was accepted into the FDA's Total Product Life Cycle Advisory Program, a selective initiative that provides device developers with ongoing FDA guidance from early development through to post-market. Together, these designations suggest the agency views the technology as addressing an unmet need, though neither constitutes an approval pathway guarantee.

Alpha DaRT works by delivering radium-224 impregnated sources directly into a tumour; as the radium decays, short-lived daughter isotopes disperse within the tumour mass, emitting alpha particles at high local doses while sparing surrounding healthy tissue. The intratumoral approach places Alpha Tau in a broader category of locoregional cancer therapies, a field that also includes convection-enhanced delivery of small molecules and various oncolytic viral approaches. Several academic groups and smaller biotechs are exploring intratumoral strategies in GBM, though no competitor has yet reached a pivotal trial using alpha-particle emitters in this setting.

The REGAIN trial's expansion to two further US academic cancer centres broadens patient access and should accelerate enrolment of the remaining seven participants. Alpha Tau chief executive Uzi Sofer said clinician demand to continue treating patients had been "overwhelming" since the interim results were published in May. The company has not yet disclosed the names of the two new sites.

With approximately 14,000 Americans diagnosed with glioblastoma annually, and recurrent disease representing an area of high unmet clinical need, the next milestone to watch is the full ten-patient safety readout, which will inform any subsequent pivotal study design and regulatory discussions with the FDA.

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