Alpha Tau Reports 100% Objective Response Rate in Six Brain Cancer Patients
Key Facts
Alpha Tau announced updated interim results from its U.S. REGAIN trial for recurrent glioblastoma and said all eight patients who received treatment were alive as of November 11, 2026. In response assessments using RANO criteria, the six evaluable patients achieved an objective response, representing a 100% response rate among them. The results included five complete responses and one partial response. The patient with the partial response recorded a 58% reduction in tumor measurements. The company presented the results in a scientific poster at the 31st annual meeting of the Society for Neuro-Oncology in Philadelphia, held from November 12 to 15, 2026.
Among the six evaluable patients, five, or 83.3%, were classified as having achieved a complete response, while one patient, or 16.7%, achieved a partial response. These percentages combine complete and partial responses to produce the 100% objective response rate under the criteria reported by the company. The 58% reduction in tumor measurements applies to the patient who achieved a partial response. Alpha Tau said one of the five patients with a complete response had been classified in an earlier assessment as having stable disease, before the response became complete with longer follow-up. This result shows a change in the classification of the patient's condition during follow-up, while the assessment remains interim.
Regarding disease progression, the company said no confirmed recurrence had been recorded in the treated area. It noted, however, that the first patient treated experienced tumor progression away from the treatment area after about nine months and then received additional treatment. This description distinguishes the treatment site from the area where progression appeared and gives the approximate timeline for the case. The company had reported one serious Grade 3 event, a seizure accompanied by temporary Todd's paralysis, which subsequently resolved. No unexpected serious events were recorded, according to the company's disclosure.
The REGAIN trial is open-label and single-arm, and aims to assess feasibility and safety in U.S. patients with recurrent glioblastoma that is not amenable to surgical resection and who have previously received central nervous system radiation. The previous design targeted enrollment of up to 10 patients before a subsequent approval allowed the trial to expand. In October 2026, the U.S. Food and Drug Administration approved raising the target to up to 20 patients at three U.S. centers. The expansion included adding patients with Grade 4 tumors carrying an IDH mutation, adding progression-free survival as a secondary assessment, periodic quality-of-life assessments and an additional interim analysis. The treatment remains unapproved for commercial use or for treating this disease outside an approved clinical trial.
Alpha DaRT technology involves inserting radium-224-labeled sources into the tumor. As radium decays, short-lived daughter products emit alpha particles that target and destroy tumor cells. The U.S. Food and Drug Administration granted the technology Breakthrough Device designation for recurrent glioblastoma in October 2021. The previous interim analysis results were based on treatment of three patients, treated consecutively in December 2025, February and March 2026. This sequence reflects the expansion of the dataset reported by the company in its current update, while the assessment remains within a single-arm trial designed to evaluate feasibility and safety.
Alpha Tau said it will hold a call to discuss the results with management and the principal investigator on November 16, 2026, at 8:30 a.m. U.S. Eastern Time, with a recording to be available afterward. The call follows the presentation of the results at the Society for Neuro-Oncology meeting held from November 12 to 15. Enrollment in the trial continues within the increased limit of up to 20 patients at three U.S. centers. The updated plan includes quality-of-life follow-up and assessment of progression-free survival as a secondary measure. The information provided did not specify a date for additional interim results.