DRTS · Alpha Tau Medical Ltd.

This 6-K filing presents a high-materiality clinical update for investors, centered on the CTP-GBM-01 trial—the first U.S. clinical study of Alpha Tau’s Alpha DaRT therapy in recurrent glioblastoma. The disclosure confirms that the FDA has imposed a controlled enrollment cadence (one patient per month) and mandated an interim safety review after the first three treated patients before permitting expansion to the full cohort of ten. This regulatory gating reflects both the novelty of the alpha-emitter approach and the high unmet need in recurrent GBM, where treatment options are extremely limited and prognosis remains poor. The trial’s dual primary endpoints—feasibility of device placement and safety—are operationally foundational: success here enables progression to pivotal development, while failure could delay or redirect the program. Preclinical data cited in Exhibit 99.1 provides mechanistic support, demonstrating potent, localized tumor control in orthotopic and xenograft models without off-target tissue damage—a key differentiator versus conventional radiotherapy. Critically, the swine brain study (Shushan et al., 2025) confirmed safe stereotactic delivery and absence of distant radiation effects, supporting use in patients previously irradiated. While no efficacy outcomes (e.g., response rate, survival) are reported for the first three patients, the fact that all were successfully treated—and that the protocol permits rapid discharge (<36 hours)—suggests favorable tolerability and procedural scalability. For investors, this represents a de-risking milestone in clinical execution, but not yet a validation of therapeutic benefit; the next material inflection will be the FDA’s decision following the interim safety readout.