Radiopharm Theranostics (NASDAQ: RADX) moves RAD202 cancer trial to Cohort 3

Rhea-AI Filing Summary

Radiopharm Theranostics reports that an independent Data Safety and Monitoring Committee has recommended advancing its Phase 1 ‘HEAT’ trial of radiotherapeutic candidate 177Lu-RAD202 to Cohort 3 at a dose of 130mCi in HER2-positive advanced solid tumors.

The decision follows favorable safety data that allowed faster progression from Cohort 2. A prior dose level of 75mCi was announced earlier, and the company states it remains on track to complete Phase 1 dose escalation by the end of 2026. RAD202 previously showed proof-of-concept and positive safety in a ten-patient HER2-positive breast cancer study.

Key Figures

New dose level: 130mCi Previous dose level: 75mCi Planned completion timing: End of 2026 +1 more

4 metrics

New dose level 130mCi Cohort 3 dose in RAD202 Phase 1 ‘HEAT’ trial

Previous dose level 75mCi Earlier announced dose level in the same Phase 1 study

Planned completion timing End of 2026 Target to complete Phase 1 dose escalation

Patients in prior study 10 patients Diagnostic HER2-positive breast cancer study showing proof-of-concept

Key Terms

Data Safety and Monitoring Committee, Phase 1 ‘HEAT’ clinical trial, HER2-positive advanced solid tumors, single-domain monoclonal antibody (sdAb), +2 more

6 terms

Data Safety and Monitoring Committee medical

"The DSMC is a multidisciplinary committee that conducts detailed reviews of study data"

An independent panel of experts that regularly reviews patient safety data and trial results during a clinical study to protect participants and ensure the study is producing reliable information. Like impartial referees who can pause, modify, or stop a trial if safety concerns or clear benefits appear, their findings can alter a drug or device’s development timeline, regulatory prospects, and investor risk, so their assessments matter for company value and timelines.

Phase 1 ‘HEAT’ clinical trial medical

"in the Phase 1 ‘HEAT’ clinical trial in patients with Human Epidermal Growth Factor Receptor 2"

HER2-positive advanced solid tumors medical

"in the Phase 1 ‘HEAT’ clinical trial in patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive advanced solid tumors"

single-domain monoclonal antibody (sdAb) medical

"RAD202 is a proprietary single-domain monoclonal antibody (sdAb) that targets the Human Epidermal Growth Factor Receptor 2"

radiopharmaceuticals medical

"a clinical-stage biopharmaceutical company focused on developing innovative oncology radiopharmaceuticals for areas of high unmet medical need"

Radiopharmaceuticals are medicines that carry tiny amounts of radioactive material to help doctors see or treat disease inside the body, acting like a tracer dye for imaging or a microscopic guided missile for targeted therapy. They matter to investors because their safety, regulatory approval, production complexity, short shelf life and hospital reimbursement determine how quickly they can reach patients and generate revenue, affecting a company’s sales potential and risk profile.

biodistribution medical

"RAD202 demonstrated clinical proof-of-concept and had positive safety and biodistribution"

Biodistribution is the map of where a drug, vaccine, or diagnostic agent travels and accumulates inside the body after administration. Investors care because where a product ends up affects how well it works, what side effects it may cause, and whether regulators will approve it—similar to tracking dye in a plumbing system to find leaks or blockages; unexpected destinations can raise safety, cost, and market-adoption risks.

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 RULE 13a-16 OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the Month of April 2026

Commission File Number: 001-41621

RADIOPHARM THERANOSTICS LIMITED

(Name of Registrant)

Level 3, 62 Lygon Street, Carlton South, Victoria, 3053, Australia

(Address of principal executive office)

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 ☐

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ☐       No ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-    

RADIOPHARM THERANOSTICS LIMITED

EXPLANATORY NOTE

Radiopharm Theranostics Limited (the “Company”) published one announcement (the “Public Notice”) to the Australian Securities Exchange on April 8, 2026 titled:

“RAD202 Phase 1 HEAT Trial Advances to Dose Level 3” 

A copy of the Public Notice is attached as an exhibit to this report on Form 6-K.

This report on Form 6-K (including the exhibit hereto) shall not be deemed to be “filed” for purposes of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and shall not be incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

1

EXHIBITS

Exhibit Number		Description
99.1		RAD202 Phase 1 HEAT Trial Advances to Dose Level 3

2

SIGNATURE

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

	RADIOPHARM THERANOSTICS LIMITED
Date: April 8, 2026	By:	/s/ Phillip Hains
		Phillip Hains
		Company Secretary

3

Exhibit 99.1

ASX ANNOUNCEMENT April 8, 2026   

Radiopharm Theranostics advances to Cohort 3 in 177Lu-RAD202 Phase 1 Dose Escalating Clinical Trial

● Receives Positive Recommendation from Data Safety and Monitoring Committee (DSMC) to progress Phase 1 to the next dose level of 130mCi in patients with HER2+ advanced solid tumors

Sydney, Australia – 8 April 2026 – Radiopharm Theranostics (ASX: RAD, Nasdaq: RADX, “Radiopharm” or the “Company”), a clinical-stage biopharmaceutical company focused on developing innovative oncology radiopharmaceuticals for areas of high unmet medical need, today announced that it has received a positive recommendation from the Data Safety and Monitoring Committee (DSMC) to advance its clinical-stage radiotherapeutic asset, 177Lu-RAD202 (RAD202), to the next dose level of 130mCi in the Phase 1 ‘HEAT’ clinical trial in patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive advanced solid tumors¹. The DSMC is a multidisciplinary committee that conducts detailed reviews of study data, discusses potential safety events and provides recommendations regarding trial continuation.

“We are encouraged by the rapid progress of the Phase 1 ‘HEAT’ trial of RAD202, as it underscores the favorable safety profile, allowing us to accelerate the dose escalation from Cohort 2 to Cohort 3.” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “Considering the current progress and the strong execution, we remain on track to complete the Phase 1 dose escalation by the end of 2026.”

The Phase 1 ‘HEAT’ study is currently being conducted at clinical centers across Australia. The announcement of the previous dose level in this study of 75mCi was released on 1 October 2025.

About 177Lu-RAD202:

RAD202 is a proprietary single-domain monoclonal antibody (sdAb) that targets the Human Epidermal Growth Factor Receptor 2 (HER2)-positive expression in advanced solid tumors. HER2 is overexpressed in breast cancer and several other solid tumors and represents a validated target in oncology. In a previous diagnostic study of ten HER2-positive breast cancer patients, RAD202 demonstrated clinical proof-of-concept and had positive safety and biodistribution.

About Radiopharm Theranostics

Radiopharm Theranostics is a clinical stage radiotherapeutics company developing a world-class platform of innovative radiopharmaceutical products for diagnostic and therapeutic applications in areas of high unmet medical need. Radiopharm is listed on ASX (RAD) and on NASDAQ (RADX). The company has a pipeline of distinct and highly differentiated platform technologies spanning peptides, small molecules and monoclonal antibodies for use in cancer. The clinical program includes one Phase 2 and five Phase 1 trials in a variety of solid tumor cancers including lung, breast, prostate and brain. Learn more at radiopharmtheranostics.com.

¹ clinicaltrials.gov/study/NCT06824155

Radiopharm Theranostics Limited
Suite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 Australia
ABN: 57 647 877 889

ASX ANNOUNCEMENT April 8, 2026   

Authorized on behalf of the Radiopharm Theranostics Board of Directors by Executive Chairman Paul Hopper.

For more information:

Investors:

Riccardo Canevari
CEO & Managing Director
P: +1 862 309 0293
E: rc@radiopharmtheranostics.com

Anne Marie Fields

Precision AQ (formerly Stern IR)

E: annemarie.fields@precisionaq.com

Media:

Matt Wright
NWR Communications
P: +61 451 896 420
E: matt@nwrcommunications.com.au

Follow Radiopharm Theranostics:

Website – https://radiopharmtheranostics.com/
X – https://x.com/TeamRadiopharm
LinkedIn – https://www.linkedin.com/company/radiopharm-theranostics/
InvestorHub – https://investorhub.radiopharmtheranostics.com/

Radiopharm Theranostics Limited
Suite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 Australia
ABN: 57 647 877 889

FAQ

What did Radiopharm Theranostics (RADX) announce about the RAD202 Phase 1 trial?

Radiopharm Theranostics reported a positive safety committee recommendation to advance RAD202 to Cohort 3 at 130mCi. This moves its Phase 1 ‘HEAT’ trial in HER2-positive advanced solid tumors to a higher dose level while maintaining the current development timeline.

What is 177Lu-RAD202 being studied for at Radiopharm Theranostics (RADX)?

177Lu-RAD202 is being studied in HER2-positive advanced solid tumors, including breast cancer. It is a proprietary single-domain monoclonal antibody radiotherapeutic targeting HER2, a receptor commonly overexpressed in several solid tumors and already considered a validated target in oncology.

What dose level has the RAD202 ‘HEAT’ Phase 1 trial reached for Radiopharm (RADX)?

The ‘HEAT’ Phase 1 trial is advancing RAD202 to a 130mCi dose level in Cohort 3. This follows an earlier reported dose level of 75mCi, reflecting stepwise dose escalation based on safety reviews by the independent Data Safety and Monitoring Committee.

When does Radiopharm Theranostics (RADX) expect to complete RAD202 Phase 1 dose escalation?

The company states it remains on track to complete the RAD202 Phase 1 dose escalation by the end of 2026. This timing relates to the ongoing ‘HEAT’ trial across Australian clinical centers, as higher dose cohorts are evaluated for safety and tolerability.

What prior clinical data support RAD202 at Radiopharm Theranostics (RADX)?

RAD202 previously showed clinical proof-of-concept, with positive safety and biodistribution, in a diagnostic study of ten HER2-positive breast cancer patients. These earlier results provide background support as the compound progresses through the current therapeutic Phase 1 dose-escalation trial.

What type of company is Radiopharm Theranostics (RADX)?

Radiopharm Theranostics is a clinical-stage radiotherapeutics company focused on radiopharmaceuticals for cancer. It is listed on ASX and NASDAQ, and its pipeline includes one Phase 2 and five Phase 1 trials targeting various solid tumors such as lung, breast, prostate and brain cancers.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 RAD202 PHASE 1 HEAT TRIAL ADVANCES TO DOSE LEVEL 3 12.3 KB