RADX 6-K
Radiopharm Theranostics Ltd (RADX)
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 August 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 ☐
RADIOPHARM THERANOSTICS LIMITED
EXPLANATORY NOTE
Radiopharm Theranostics Limited (the “Company”) published one announcement (the “Public Notice”) to the Australian Securities Exchange on August 20, 2026 titled:
“RAD advances to Cohort 4 in 177Lu-RAD202 Phase 1 HEAT Trial”
A copy of the Public Notice is attached as an exhibit to this report on Form 6-K.
This Form 6-K, including the exhibits hereto, is incorporated by reference into the registration statement of the Company on Form F-3 (File No. 333-292178) and forms part thereof to the extent not superseded by documents or reports subsequently filed by the Company under the Securities Act of 1933 or the Securities Exchange Act of 1934.
1
EXHIBITS
| Exhibit <br><br>Number | Description |
|---|---|
| 99.1 | RAD advances to Cohort 4 in 177Lu-RAD202 Phase 1 HEAT Trial |
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: August 20, 2026 | By: | /s/ Amritha Sushil |
| Amritha Sushil | ||
| Company Secretary |
3
Exhibit 99.1
| ASX ANNOUNCEMENT<br><br> <br>August 20, 2026 |  |
|---|
RadiopharmTheranostics Receives Positive Recommendation from Data Safety and Monitoring Committee to Advance to Cohort 4 in 177Lu-RAD202 Phase 1HEAT Clinical Trial
Advancing RAD202 Phase 1 trial to next doselevel of 180mCi in patients with HER2+ advanced solid tumors
Previous diagnostic study of RAD202 in ten HER2-positivebreast cancer patients demonstrated clinical proof-of-concept with positive safety and biodistribution
Sydney, Australia – 20 August 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 180mCi in the Phase 1 ‘HEAT’ clinical trial in patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive advanced solid tumors^1^. The DSMC is a multidisciplinary committee that conducts detailed reviews of study data, discusses potential safety events and provides recommendations regarding trial continuation.
“Advancing RAD202 into Cohort 4 marks a significant step forward in the development of one of our most promising therapeutic candidates,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “The DSMC’s recommendation supports the favorable safety profile observed to date and allows us to continue evaluating higher dose levels in patients with HER2-positive advanced solid tumors. As we execute on our clinical development strategy, we remain focused on unlocking the full potential of RAD202 and generating meaningful data that could support a differentiated radiotherapeutic option for HER2-positive patients in need of new treatment alternatives.”
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 130mCi was released on 8 April 2026.
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.
| ^1^ | clinicaltrials.gov/study/NCT06824155 |
|---|
Radiopharm Theranostics LimitedSuite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 AustraliaABN: 57 647 877 889
| ASX ANNOUNCEMENT<br><br> <br>August 20, 2026 | |
|---|
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.
Authorized on behalf of the RadiopharmTheranostics Board of Directors by Executive Chairman Paul Hopper.
For more information:
Investors:
Riccardo Canevari
CEO & Managing Director
P: +1 862 309 0293
Anne Marie Fields
Precision AQ (formerly Stern IR)
Media:
Matt Wright
NWR Communications
P: +61 451 896 420
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 LimitedSuite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 AustraliaABN: 57 647 877 889