Alpha Tau (Nasdaq: DRTS) hits milestone in U.S. pivotal skin cancer trial

Rhea-AI Filing Summary

Alpha Tau Medical Ltd. has completed enrollment of 88 patients in its ReSTART pivotal trial, a multicenter U.S.-led study of Alpha DaRT for recurrent cutaneous squamous cell carcinoma. This first U.S. pivotal study to fully enroll supports Alpha Tau’s modular FDA pre-market approval application, following Breakthrough Device Designation for Alpha DaRT in this indication.

Positive

• Completion of pivotal trial enrollment: ReSTART, Alpha Tau’s first U.S. pivotal study of Alpha DaRT in recurrent cutaneous squamous cell carcinoma, has fully enrolled 88 patients and is intended to support a modular FDA PMA submission in an area of significant unmet medical need.

Negative

• None.

Insights

Biotech & regulatory strategy analyst

Completion of pivotal enrollment moves Alpha DaRT closer to potential FDA approval.

Alpha Tau has finished enrolling 88 patients in its ReSTART pivotal trial for recurrent cutaneous squamous cell carcinoma, the first U.S. pivotal study for its Alpha DaRT therapy. The device already holds FDA Breakthrough Device Designation, and the company has begun a modular pre-market approval submission.

The trial’s co-primary endpoints are objective response rate and six‑month duration of response, with additional survival and quality‑of‑life measures. Results from this study are intended to form the core evidence package for potential U.S. market approval in a setting with significant unmet need.

The impact will depend on the eventual efficacy and safety outcomes once follow‑up is complete and data mature. Combined with prior skin cancer studies in Israel, Italy, France and a U.S. pilot, this pivotal dataset could meaningfully shape Alpha Tau’s commercialization prospects if outcomes align with earlier signals.

Key Figures

ReSTART enrollment: 88 patients Primary DOR endpoint horizon: 6 months Survival follow-up: 1 year

3 metrics

ReSTART enrollment 88 patients Pivotal trial population for recurrent cutaneous squamous cell carcinoma

Primary DOR endpoint horizon 6 months Duration of response measured from initial observation of response

Survival follow-up 1 year Progression-free and overall survival secondary endpoints at one year

Key Terms

pivotal study, Breakthrough Device Designation, pre-market approval (PMA), objective response rate (ORR), +2 more

6 terms

pivotal study clinical

"First U.S. pivotal study for Alpha Tau to have completed enrollment"

A pivotal study is a large, definitive clinical trial designed to show whether a medical product works and is safe enough for regulators to approve and for doctors to use. Think of it as the final exam that determines whether a drug or device moves from testing into the market; its results can dramatically change a company’s approval chances, future sales prospects, and therefore its stock value.

Breakthrough Device Designation regulatory

"for which the Alpha DaRT has received Breakthrough Device Designation from the FDA"

A breakthrough device designation is a regulatory program that gives promising medical devices for serious or life‑threatening conditions priority support and faster review from a health authority (e.g., the U.S. FDA). Think of it as a “fast lane” or VIP pass through development and review: it can shorten time to market, lower regulatory uncertainty, and boost a company’s commercial prospects — but it is not an approval by itself.

pre-market approval (PMA) regulatory

"towards potential FDA pre-market approval (PMA); Company has already initiated PMA modular application process"

Pre-market approval (PMA) is the most rigorous regulatory review process for high-risk medical devices, where a regulatory agency (such as the U.S. FDA) evaluates detailed clinical and manufacturing evidence to determine whether the device is safe and effective for sale. For investors, PMA matters because approval can unlock commercial sales and revenue after a lengthy, costly review—like receiving a final building permit that allows construction and occupancy after extensive inspections.

objective response rate (ORR) clinical

"co-primary endpoints are the objective response rate (ORR) based on confirmed best overall response"

The objective response rate (ORR) is the percentage of patients in a clinical trial whose tumors shrink by a pre-set amount for a minimum time, counting both complete disappearance and meaningful partial shrinkage. Investors watch ORR because it gives an early, quantitative signal that a treatment is having a direct effect on disease—like the percent of people whose fever drops after taking a medicine—which can influence expectations for later trial success, regulatory approval, and market potential.

progression-free survival clinical

"Secondary endpoints include progression-free survival and overall survival at one year"

Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

intratumoral clinical

"evaluating the efficacy and safety of intratumoral Alpha DaRT for the treatment"

"Intratumoral" describes something that occurs or exists within a tumor, which is an abnormal growth of tissue. For investors, understanding intratumoral is important because it relates to medical treatments or research aimed at targeting the tumor directly, potentially leading to more effective therapies. Think of it as focusing treatment straight into the problem area, much like fixing a leak by working directly on the pipe itself.

Form 6-K: How Foreign Companies Report to the SEC →

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO SECTION 13A-16 OR 15D-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2026

Commission File Number: 001-41316

Alpha Tau Medical Ltd.

(Exact Name of Registrant as Specified in Its Charter)

Kiryat HaMada St. 5

Jerusalem, Israel 9777605

+972 (3) 577-4115

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒         Form 40-F ☐

CONTENTS

On May 8, 2026, Alpha Tau Medical Ltd. (the “Company”) issued a press release titled “Alpha Tau Completes Patient Enrollment in its U.S. Pivotal Skin Cancer Study, Advancing Towards Goal of FDA Approval of Alpha DaRT® to Treat Recurrent Cutaneous Squamous Cell Carcinoma.” A copy of this press release is attached to this Form 6-K as Exhibit 99.1.

The information in this Report on Form 6-K, including Exhibit 99.1 attached hereto, is being furnished and shall not be deemed “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference in any filing made by the Company under the Securities Act of 1933, as amended, or the Exchange Act, except as otherwise set forth herein or as shall be expressly set forth by specific reference in such a filing.

1

EXHIBIT INDEX

Exhibit No.		Description
99.1		Press release dated May 8, 2026.

2

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	Alpha Tau Medical Ltd.
Date: May 8, 2026	By:	/s/ Uzi Sofer
		Uzi Sofer
		Chief Executive Officer

3

Exhibit 99.1

Alpha Tau Completes Patient Enrollment in its U.S. Pivotal Skin Cancer Study, Advancing Towards Goal of FDA Approval of Alpha DaRT^® to Treat Recurrent Cutaneous Squamous Cell Carcinoma

- First U.S. pivotal study for Alpha Tau to have completed enrollment, representing a critical milestone on the path towards potential FDA pre-market approval (PMA); Company has already initiated PMA modular application process -

- Enrollment of all 88 patients completed in the ReSTART trial, a U.S. multicenter pivotal study evaluating Alpha DaRT® for the treatment of recurrent cutaneous squamous cell carcinoma (cSCC), for which the Alpha DaRT has received Breakthrough Device Designation from the FDA -

- ReSTART pivotal study builds on a foundation of clinical data from skin cancer studies conducted in Israel, Italy, France and the U.S. -

- cSCC is the second most common form of skin cancer, with a rising incidence and a significant unmet need for patients who have exhausted surgical and conventional treatment options -

Jerusalem, May 8, 2026 - Alpha Tau Medical Ltd. (Nasdaq: DRTS, DRTSW) (“Alpha Tau”), the developer of the innovative alpha-radiation cancer therapy Alpha DaRT®, today announced the completion of enrollment in its ReSTART pivotal trial (Recurrent SCC Treatment with Alpha DaRT Radiation Therapy), a U.S. multicenter study evaluating the efficacy and safety of intratumoral Alpha DaRT for the treatment of patients with recurrent cutaneous squamous cell carcinoma (cSCC). This is the first U.S. pivotal clinical study of Alpha Tau to have completed enrollment, representing a landmark milestone in the Company’s journey towards potential FDA PMA approval of Alpha DaRT in this indication.

Uzi Sofer, CEO of Alpha Tau, stated, “The completion of enrollment in the ReSTART pivotal trial is a watershed moment for Alpha Tau. Skin cancer was the very first clinical application of Alpha DaRT, and it has served as the cornerstone of our entire clinical development strategy. The years of evidence we have generated across multiple countries and numerous patients have consistently demonstrated the strength of our intratumoral radiotherapeutic approach - providing the foundation not only for this pivotal study, but also for our expanding clinical programs in additional indications. Completing enrollment in our first-ever U.S. pivotal trial - the study designed to support our first potential FDA approval - brings us closer than ever to potential commercialization. We look forward to continued progress on our modular PMA submission and to ultimately bringing Alpha DaRT to market.”

A pivotal study is a definitive clinical trial designed to provide the primary evidence of a medical product’s safety and efficacy upon which the FDA relies when evaluating whether to grant market approval. The completion of enrollment in the ReSTART trial marks a critical transition from patient recruitment to follow-up and data maturation, bringing Alpha Tau one step closer to a potential commercial approval of Alpha DaRT in the United States.

The ReSTART trial is a prospective, multicenter, single-arm, open-label pivotal study which enrolled 88 patients with biopsy-proven recurrent cSCC who have failed at least first-line standard-of-care therapy and who are not indicated for surgery or conventional treatment, and for whom no curative systemic treatment is available. The study’s co-primary endpoints are the objective response rate (ORR) based on confirmed best overall response, and the duration of response (DOR) at six months from the initial observation of response. Secondary endpoints include progression-free survival and overall survival at one year, overall duration of response, local control, and quality of life. With enrollment now complete, the study will proceed through its follow-up period to allow for assessment of these primary and secondary endpoints.

Cutaneous squamous cell carcinoma is the second most common form of skin cancer, with an incidence that continues to rise globally. While surgical excision effectively treats the majority of cSCC cases, a meaningful subset of patients develops recurrent disease that can no longer be managed with surgery or conventional treatments. For these patients there remains a significant unmet need for effective, well-tolerated treatments. Alpha DaRT, designed to deliver a targeted intratumoral radiotherapeutic treatment directly to the tumor, seeks to offer a new approach for this underserved population.

The ReSTART pivotal study builds on a robust foundation of clinical evidence generated through multiple skin cancer studies conducted in Israel, Italy and France, as well as a pilot study in the U.S. Together, clinicians in these studies have treated hundreds of tumors and have consistently observed promising efficacy and favorable safety of Alpha DaRT. Alpha Tau has received Breakthrough Device Designation from the FDA for Alpha DaRT in the treatment of recurrent cSCC, and submitted the first module of its modular PMA application in January 2026.

Robert B. Den, MD, Chief Medical Officer of Alpha Tau, stated, “Alpha DaRT’s journey in skin cancer has spanned years and continents. It began with foundational studies in Israel and Italy, expanded to France, and progressed to a pilot study in the United States - each study building upon the last and reinforcing the clinical evidence behind this technology. The ReSTART pivotal study, with a very large patient population of 88, represents the most rigorous evaluation of Alpha DaRT to date, and I want to express my sincere gratitude to all of the principal investigators who recruited patients into this trial. Their belief in the potential of Alpha DaRT to make a real difference for patients with recurrent cSCC - patients who have exhausted surgical and other curative options - has been instrumental in reaching this milestone. It is their commitment to clinical excellence and to their patients that brought us to this point.”

Liron Dimnik, VP Clinical Affairs at Alpha Tau, commented, “Completing enrollment in a multicenter pivotal trial is an enormous operational undertaking, and I am incredibly proud of the team that made it happen. I want to thank our clinical operations team at Alpha Tau, who worked tirelessly to ensure that every aspect of the study - from site activation to data quality to regulatory compliance - was executed to the highest standards. I also want to recognize the physicians, study coordinators and site teams at every participating center, whose day-to-day dedication to patient care and protocol adherence is the backbone of any successful clinical trial. We now transition into the follow-up phase with confidence, knowing that the foundation we have built together is strong.”

About the ReSTART Trial

The ReSTART trial (Recurrent SCC Treatment with Alpha DaRT Radiation Therapy) is a prospective, multicenter, single-arm, open-label pivotal clinical study evaluating the efficacy and safety of intratumoral Alpha DaRT for the treatment of patients with recurrent cutaneous squamous cell carcinoma (cSCC) who have failed at least first-line standard-of-care therapy and are not indicated for surgery or conventional treatment. The study enrolled 88 patients across clinical centers in the United States, Israel, and Canada. The co-primary endpoints are the objective response rate (ORR) based on confirmed best overall response and the duration of response (DOR) at six months from the initial observation of response. Secondary endpoints include progression-free survival and overall survival at one year, overall duration of response, local control, and quality of life. Alpha DaRT has received Breakthrough Device Designation from the FDA for this indication, and the Company submitted the first module of its modular pre-market approval (PMA) application in January 2026. Additional information about the trial can be found at https://clinicaltrials.gov/study/NCT05323253.

About Alpha DaRT^®

Alpha DaRT (Diffusing Alpha-emitters Radiation Therapy) is designed to enable highly potent and conformal intratumoral treatment of solid tumors. Alpha DaRT sources are inserted directly into the tumor, where they release short-lived therapeutic particles that disperse locally with the goal of destroying the tumor. Since the therapeutic effect is confined to a short distance, Alpha DaRT aims to mainly affect the tumor and to spare the healthy tissue around it.

About Alpha Tau Medical Ltd.

Founded in 2016, Alpha Tau is an Israeli oncology therapeutics company that focuses on research, development, and potential commercialization of the Alpha DaRT for the treatment of solid tumors. The technology was initially developed by Prof. Itzhak Kelson and Prof. Yona Keisari from Tel Aviv University.

Forward-Looking Statements

This press release includes “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. When used herein, words including “anticipate,” “will,” “plan,” “may,” “continue,” and similar expressions are intended to identify forward-looking statements. In addition, any statements or information that refer to the Alpha DaRT treatment in patients with recurrent cSCC, including the potential benefits and associated risks, future applications and uses, the ReSTART pivotal study, the PMA submission, and potential indication approvals, are forward-looking. All forward-looking statements are based upon Alpha Tau’s current expectations and various assumptions. Alpha Tau believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. Alpha Tau may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various important factors, including, without limitation: (i) Alpha Tau’s ability to receive regulatory approval for its Alpha DaRT technology or any future products or product candidates; (ii) Alpha Tau’s limited operating history; (iii) Alpha Tau’s incurrence of significant losses to date; (iv) Alpha Tau’s need for additional funding and ability to raise capital when needed; (v) Alpha Tau’s limited experience in medical device discovery and development; (vi) Alpha Tau’s dependence on the success and commercialization of the Alpha DaRT technology; (vii) the failure of preliminary data from Alpha Tau’s clinical studies to predict final study results; (viii) failure of Alpha Tau’s early clinical studies or preclinical studies to predict future clinical studies; (ix) Alpha Tau’s ability to enroll patients in its clinical trials; (x) undesirable side effects caused by Alpha Tau’s Alpha DaRT technology or any future products or product candidates; (xi) Alpha Tau’s exposure to patent infringement lawsuits; (xii) Alpha Tau’s ability to comply with the extensive regulations applicable to it; (xiii) the ability to meet Nasdaq’s listing standards; (xiv) costs related to being a public company; (xv) changes in applicable laws or regulations; and the other important factors discussed under the caption “Risk Factors” in Alpha Tau’s annual report filed on form 20-F with the SEC on March 9, 2026, and other filings that Alpha Tau may make with the United States Securities and Exchange Commission. These and other important factors could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While Alpha Tau may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause its views to change. These forward-looking statements should not be relied upon as representing Alpha Tau’s views as of any date subsequent to the date of this press release.

Investor Relations Contact:

IR@alphatau.com

FAQ

What did Alpha Tau Medical Ltd. (DRTS) announce in this Form 6-K?

Alpha Tau announced it has completed enrollment of 88 patients in its ReSTART pivotal trial of Alpha DaRT for recurrent cutaneous squamous cell carcinoma, its first U.S. pivotal study, marking a key step toward potential FDA pre-market approval for this skin cancer indication.

What is the ReSTART pivotal trial for Alpha Tau (DRTS)?

ReSTART is a prospective, multicenter, single-arm, open-label pivotal study evaluating intratumoral Alpha DaRT in 88 patients with recurrent cutaneous squamous cell carcinoma who failed first-line therapy and are not surgical candidates, with co-primary endpoints of objective response rate and six-month duration of response.

How does the ReSTART study support Alpha Tau’s FDA plans for Alpha DaRT?

ReSTART is designed as the definitive pivotal trial providing primary safety and efficacy evidence for Alpha DaRT in recurrent cutaneous squamous cell carcinoma. Completion of enrollment allows follow-up and data maturation to proceed, feeding into Alpha Tau’s ongoing modular FDA pre-market approval application for this indication.

What regulatory designations has Alpha DaRT received for recurrent cSCC?

Alpha DaRT has received FDA Breakthrough Device Designation for treating recurrent cutaneous squamous cell carcinoma. Alpha Tau has also submitted the first module of a modular pre-market approval application, positioning ReSTART’s clinical results as a central part of the evidence package for potential U.S. market authorization.

What are the main endpoints in Alpha Tau’s ReSTART pivotal study?

ReSTART’s co-primary endpoints are objective response rate based on confirmed best overall response and duration of response at six months from initial response. Secondary endpoints include progression-free survival and overall survival at one year, overall duration of response, local tumor control, and patient quality of life.

Why is Alpha Tau’s Alpha DaRT therapy significant for recurrent cutaneous SCC?

Alpha DaRT delivers targeted intratumoral alpha-radiation, aiming to destroy tumors while sparing nearby healthy tissue. In recurrent cutaneous squamous cell carcinoma, where surgery and conventional treatments may be exhausted, this approach seeks to address a substantial unmet need for effective and tolerable local therapies.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 PRESS RELEASE DATED MAY 8, 2026 18.0 KB