Enrollment Milestone

Alpha Tau's implanted-seed trial in recurrent GBM targets enrollment finish by H2 2026

The 10-patient feasibility study testing whether Alpha DaRT's radioactive seeds can be placed safely in recurrent glioblastoma is recruiting toward a stated second-half 2026 enrollment finish, with survival and safety data to follow.

By AppliedXLJuly 13, 2026Trial NCT06910306

Executive Summary

Alpha Tau is recruiting toward finishing enrollment in a small pilot study testing whether its alpha-emitting radiation seeds can be safely placed in recurrent glioblastoma, extending a device platform already tested in other solid tumors into brain cancer.
The trial's primary questions are feasibility of seed placement and adverse-event safety, not tumor response, so the data due after enrollment completes will read as a tolerability and technical-execution signal rather than an efficacy verdict.
Recurrent glioblastoma has no mechanism in this competitive field with a validated disease-modifying benefit, and alpha-emitter brachytherapy has no direct precedent tested in this tumor type, making this pilot a first look at whether the approach is deliverable at all in the brain.
The trial's enrollment target, completion timeline, and protocol have stayed unchanged since the study opened, indicating an on-track early-stage study rather than one under operational strain.

The trial

The study, registered as NCT06910306, is enrolling 10 adult patients with recurrent glioblastoma who are not candidates for surgical resection, using Alpha Tau's Diffusing Alpha-emitter Radiation Therapy (DaRT) seeds implanted directly into the tumor. The trial opened to recruitment in December 2025, after starting as not-yet-recruiting in October 2025, and its two primary endpoints are feasibility of DaRT seed placement and the incidence of adverse events, with overall survival and radiographic tumor control tracked as secondary measures. Alpha Tau treated its first patient in the study in December, the company said in its March 2026 corporate update, describing glioblastoma as one of the most difficult and treatment-resistant cancers, with an average survival of about 8 months. NCT06910306+1

Probability of Success

Endpoint Met33%

Completes51%

Clinical Significance4%

Regulatory85%

The stated timeline

Alpha Tau has told investors it expects to complete patient recruitment in the trial in the second half of 2026, a window that runs from July 1 through December 31. That guidance is consistent with the registry's own primary completion date of November 1, 2026. The company's most recent update also pointed to an initial safety readout from the first three patients in the trial in the second quarter of 2026, ahead of the full enrollment completion. Alpha+1

What has not changed

The trial has recorded only two registry events since it was first posted: the initial listing in April 2025 and the status change to Recruiting in December 2025. Its enrollment target has stayed at 10 patients, and there have been no amendments to the primary completion date, endpoints, or eligibility criteria. For a 10-patient early-stage feasibility study, holding a fixed target through the recruiting period is the ordinary course, not a signal of strain. NCT06910306

The competitive field

Alpha DaRT has received FDA Breakthrough Device Designation for recurrent glioblastoma and was accepted into the FDA's Total Product Life Cycle Advisory Program pilot for the same indication, both signals of the agency's engagement with an unmet-need setting rather than any endpoint result. Recurrent glioblastoma's competitive field includes other local-therapy approaches in later-stage testing, such as GT Medical Technologies' GammaTile brachytherapy implant and NovoCure's Optune tumor-treating-fields device, alongside small-molecule and gene-therapy programs, but none shares Alpha DaRT's alpha-particle-emitting mechanism. No trial identified in this competitive field carries a validated disease-modifying survival benefit in recurrent glioblastoma, which is what any completed readout from this pilot would eventually need to bear on to be informative beyond feasibility.

What the readout will test

Because the trial's own endpoints are feasibility and safety rather than efficacy, the data that follows enrollment completion will establish whether the seeds can be placed as intended and whether the implantation procedure and radiation dose produce a manageable adverse-event profile in this population. That is the threshold this specific pilot design can clear; overall survival and tumor-control data collected as secondary measures will provide an early look at biological activity, but the study is not built to generate a registrational efficacy result. NCT06910306

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