Alpha Tau Medical Ltd. announced that the first two patients were enrolled and treated in its pivotal multicenter trial, known as the ReSTART trial (Recurrent SCC Treatment with Alpha DaRT Radiation Therapy), for the treatment of recurrent cutaneous squamous cell carcinoma (cSCC). The patients were treated at the University Cancer Center in Houston, Texas. The trial is intended to enroll up to 86 participants who have biopsy-proven recurrent cSCC who are not otherwise indicated for surgery or standard radiation therapy, and for whom no curative systemic treatment is available.

The primary study endpoints include overall objective response rate, based on best overall response, duration of response at 6-months from initial observation of a response to Alpha DaRT insertion, and safety of the Alpha DaRT treatment. The study's secondary objectives are to assess the progression-free survival and overall survival at 1-year following Alpha DaRT treatment, overall duration of response, local control, and quality of life. Alpha DaRT (Diffusing Alpha-emitters Radiation Therapy) is designed to enable highly potent and conformal alpha-irradiation of solid tumors by intratumoral delivery of radium-224 impregnated sources.

When the radium decays, its short-lived daughters are released from the sources and disperse while emitting high-energy alpha particles with the goal of destroying the tumor. Since the alpha-emitting atoms diffuse only a short distance, Alpha DaRT aims to mainly affect the tumor, and to spare the healthy tissue around it.