FDA Clears Alpha DaRT Trial to Complete Enrollment in Recurrent GBM

The FDA has cleared Alpha Tau Medical Ltd. to proceed with enrollment of the remaining 7 patients in its interventional US REGAIN (Recurrent Glioblastoma Alpha-DaRT Intratumoral Therapy) trial (NCT06910306), according to a news release from the company.¹ The FDA has also permitted 2 new US academic centers to join the REGAIN trial as participating sites. The agency’s decision follows a review of a pre-specified interim safety report covering the first 3 patients treated in the study. Based on this decision, the developer plans to immediately begin patient recruitment once more.

What were the early interim results from the REGAIN trial?

Interim results from the first 3 patients, who were treated with Alpha-DaRT (Diffusing Alpha-emitters Radiation Therapy) between December 2025 and March 2026 at The Ohio State University Comprehensive Cancer Center (OSUCCC) in Columbus, Ohio, demonstrated 100% local disease control and a 67% complete response rate defined by Response Assessment in Neuro-Oncology (RANO) criteria. As of the data cutoff of May 3, 2026, no patients had experienced local or distant recurrence or residual procedural symptoms. One associated grade 3 serious adverse event (SAE) was reported and fully resolved; no unanticipated SAEs were observed.

“In recurrent [glioblastoma], where objective response rates with most systemic therapies rarely reach double digits, seeing 2 patients achieve complete disappearance of all enhancing tumor lesions on serial MRI scans as of the cutoff date, while the third showed meaningful tumor volume reduction, is a clinically significant and encouraging pattern,” stated Robert Den, MD, chief medical officer of Alpha Tau, in the press release.¹ “The [AE] profile was manageable: 1 grade 3 SAE, fully resolved, with no unanticipated toxicities. This is the kind of consistent, interpretable signal that gives us confidence as we advance to the next set of patients.”

What is the REGAIN trial design?

The REGAIN study is a prospective, open-label, single-arm trial designed to enroll up to 10 patients in the US with recurrent glioblastoma not amenable to surgical resection who have previously undergone central nervous system radiation.

Eligible patients were between 18 and 85 years of age with a histologically confirmed diagnosis of World Health Organization grade IV glioblastoma and a single, gadolinium-enhancing tumor recurrence 3 cm or less in maximum diameter.² Patients also had measurable disease per RANO criteria, an estimated life expectancy of at least 6 months, and a Karnofsky performance score of at least 60 documented within 14 days of trial registration.

The primary objectives are the feasibility, defined as the successful placement of Alpha DaRT sources into brain tumors, as well as the safety, defined as the incidence of acute grade 3 or higher unanticipated AEs, of Alpha DaRT treatment.

What is Alpha DaRT and how does it work?

Alpha DaRT is an intratumoral device designed to deliver conformal alpha-irradiation to solid tumors via radium-224–impregnated sources. When the radium decays, short-lived daughter atoms are released and disperse within the tumor while emitting high-energy alpha particles. This mechanism is intended to damage tumor cells while limiting radiation exposure to surrounding healthy tissue.

What is Alpha DaRT’s regulatory history in glioblastoma?

The clearance to continue enrollment follows a series of FDA regulatory interactions for Alpha DaRT in recurrent glioblastoma. The agency granted breakthrough device designation for the indication in October 2021.³ In October 2024, Alpha Tau was accepted into the FDA's Total Product Life Cycle (TPLC) Advisory Program (TAP) Pilot, an initiative designed to expedite patient access to promising medical devices by providing guidance throughout the development process.

Secondarily, results from Alpha DaRT in pancreatic adenocarcinoma from 2 clinical protocols were shared at Digestive Disease Week (DDW) 2026 earlier this year. CancerNetwork® covered those results and spoke with Philip Blumenfeld, MD, about their significance.⁴

References

1. Alpha Tau receives FDA clearance to complete enrollment in REGAIN recurrent glioblastoma trial and add 2 US clinical sites; early interim results showed 100% local disease control. News release. Alpha Tau Medical Ltd. June 11, 2026. Accessed June 15, 2026. https://tinyurl.com/39kbkm2s
2. Alpha radiation emitters device (DaRT) for the treatment of recurrent glioblastoma. ClinicalTrials.gov. Updated April 6, 2026. Accessed June 15, 2026. https://tinyurl.com/42y7a7km
3. Alpha Tau receives FDA's breakthrough device designation for the treatment of recurrent GBM. News release. Alpha Tau Medical. October 8, 2021. Accessed June 15, 2026. https://tinyurl.com/phsmt8pr
4. Blumenfeld P. Updated results of feasibility, safety, and tumor control in two first-in-human trials of a novel alpha-emitting radionuclide for pancreatic adenocarcinoma. Presented at: Digestive Disease Week 2026; May 2-5, 2026; Chicago, IL.