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 November 2025
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 November 18, 2025 titled:
“RAD Approval for Phase 1 Therapeutic Trial of RAD 402”
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 <br><br>Number | Description |
|---|---|
| 99.1 | RAD Approval for Phase 1 Therapeutic Trial of RAD 402 |
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: November 18, 2025 | By: | /s/ Phillip Hains |
| Phillip Hains | ||
| Company Secretary |
3
Exhibit99.1
| ASX ANNOUNCEMENT18 NOVEMBER 2025 |
|---|
RadiopharmTheranostics Receives Approval to Initiate Phase 1 Therapeutic Trial of RAD 402 (KLK3-mAb with Tb161) in Advanced Prostate Cancer
RAD 402 is a humanized IgG1 internalized byprostate cells, binding KLK3 with high affinity
Tb-161 antitumor activity driven by the dualemission of beta particles and Auger electrons
Sydney, Australia – 18 November 2025 – Radiopharm Theranostics (ASX:RAD, “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 been granted Bellberry Human Research Ethics Committee (HREC) approval in Australia to initiate its First-In-Human (FIH) Phase 1 clinical trial of its Kallikrein Related Peptidase 3 (KLK3)-targeting radiotherapeutic, RAD 402, for the treatment of metastatic or locally advanced prostate cancer.
RAD 402 is an anti-KLK3 monoclonal antibody radiolabelled with the radionuclide 161Tb for the treatment of prostate cancer. Prostate Specific Antigen (PSA) is a widely used biomarker to detect prostate cancer and is encoded by the KLK3 gene. KLK3 is expressed in the prostate along with most adenocarcinomas of the prostate including their metastases.
Previous comprehensive preclinical proof-of-concept Biodistribution studies of RAD 402 in mouse xenografts showed strong tumour targeting, limited bone and marrow uptake, and a hepatic excretion profile consistent with expectations for a monoclonal antibody. Radiopharm has signed in 2022 a supply agreement with Terthera for the production of Tb161 and in 2025 with Cyclotek for radiolabeling RAD402 with 161Tb, supporting the initiation of the Phase 1 FiH trial of RAD 402.
“Receiving HREC approval marks a key milestone for Radiopharm and for patients in need of safer, more effective new treatments for prostate cancer,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “This clearance enables us to advance RAD 402 into our first-in-human Phase 1 clinical trial, which, to my knowledge, is the first company-sponsored therapeutic trial using 161Tb. We are highly encouraged by RAD 402’s potential antitumor activity, driven by the dual emission of beta particles and Auger electrons from Tb-161. Targeting KLK3 in advanced prostate cancer represents a novel and promising mechanism of action. The strength of our preclinical data, combined with regulatory endorsement, underscores RAD 402’s first-in-class potential”.
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 four Phase 1 trials in a variety of solid tumor cancers, including lung, breast, and brain metastases. Learn more at radiopharmtheranostics.com.
Radiopharm Theranostics LimitedSuite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 AustraliaABN: 57 647 877 889
| ASX ANNOUNCEMENT18 NOVEMBER 2025 |
|---|
Authorised on behalf of the Radiopharm Theranostics board of directors by Chairman PaulHopper.
For more information:
Riccardo Canevari
CEO & Managing Director
P: +1 862 309 0293
Anne Marie Fields
Precision AQ (Formerly Stern IR)
Paul Hopper
Executive Chairman
P: +61 406 671 515
Media
Matt Wright
NWR Communications
P: +61 451 896 420
Radiopharm TheranosticsLimitedSuite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 AustraliaABN: 57 647 877 889