Radiopharm Theranostics (NASDAQ: RADX) starts RAD 402 prostate cancer trial
Rhea-AI Filing Summary
Radiopharm Theranostics Limited reported that it has dosed the first patient in its first-in-human Phase 1 clinical trial of RAD 402 for advanced prostate cancer. This early-stage study will assess safety, tolerability, whole-body distribution, and initial signs of clinical activity.
RAD 402 is a monoclonal antibody targeting KLK3, radiolabelled with Terbium 161, aiming to selectively attack KLK3-expressing prostate tumors while limiting damage to healthy tissue. Preclinical mouse xenograft data showed strong tumor targeting, minimal bone and marrow uptake, and hepatic clearance, and the company expects to share data from the first two dose levels in the second half of 2026.
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Insights
First-patient dosing in RAD 402 Phase 1 initiates human testing but remains an early, high-risk development stage.
The company has begun a first-in-human Phase 1 trial of RAD 402, targeting KLK3 in advanced prostate cancer. The study focuses on safety, tolerability, biodistribution, and preliminary activity, and will determine the maximum tolerated dose and recommended Phase 2 dose.
Preclinical mouse xenograft data showed strong tumor targeting, limited bone and marrow uptake, and hepatic clearance, supporting the move into human testing. Initial clinical data from the first two dose levels are expected in the second half of 2026, which will help assess whether the preclinical profile translates clinically.
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 March 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 March 27, 2026 titled:
“RAD Doses First Patient in RAD 402 Phase 1 Clinical Study”
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 | RAD Doses First Patient in RAD 402 Phase 1 Clinical Study |
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: March 27, 2026 | By: | /s/ Phillip Hains |
| Phillip Hains | ||
| Company Secretary | ||
3
Exhibit 99.1
ASX ANNOUNCEMENT 27 March 2026 |
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Radiopharm Theranostics Doses First Patient in Phase 1 Clinical Study of RAD 402 in Advanced Prostate Cancer
On track to share data from first two dose levels in 2H 2026
Targeting KLK3 and leveraging the dual emission of Tb161 represents an innovative approach for radiotherapies in Prostate Cancer
Preclinical proof-of-concept mouse xenografts demonstrated RAD 402’s strong tumor targeting with minimal bone/marrow uptake and expected hepatic clearance
Sydney, Australia – 27 March 2026 – 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 the first patient has been dosed in its first-in-human Phase 1 clinical trial of RAD 402, a monoclonal antibody targeting KLK3 radiolabelled with Terbium 161 being evaluated in advanced prostate cancer.
The Phase 1 clinical trial (NCT07259213) is designed to study the safety, tolerability, whole-body distribution, and preliminary clinical activity of RAD 402 in patients with advanced prostate cancer. The dose escalation Phase 1 study is designed to determine the Maximum Tolerated Dose (MTD) and/or recommended phase 2 dose (RP2D) for expansion.
“Dosing the first patient in our Phase 1 study of RAD 402 marks an important step forward for Radiopharm and for patients with advanced prostate cancer,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “RAD 402 is a differentiated, first-in-class, next-generation radiotherapeutic designed to selectively target KLK3-expressing tumors while minimizing off-target exposure. With preclinical data demonstrating strong tumor uptake and minimal bone or marrow involvement, we are optimistic about its potential clinical profile. Advancing this program into the clinic reflects our continued commitment to delivering meaningful data across our portfolio this year. I like to take the opportunity to thank our partners, TerThera and Cyclotek, for the great support in supplying Tb161, radiolabelling, and distributing RAD 402.”
About RAD 402
RAD 402 (NCT07259213) is an anti-KLK3 monoclonal antibody radiolabelled with the radionuclide 161Tb that is being evaluated in a Phase 1/2a clinical trial 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 highly expressed in prostate cancer cells along with most adenocarcinomas of the prostate including their metastases and has limited expression in sites outside of the prostrate. Preclinical proof-of-concept biodistribution studies of RAD 402 in mouse xenografts showed strong tumor targeting, limited bone and marrow uptake, and a hepatic excretion profile consistent with expectations for a monoclonal antibody.
Radiopharm Theranostics Limited
Suite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 Australia
ABN: 57 647 877 889
ASX ANNOUNCEMENT 27 March 2026 |
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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, prostate and brain metastases. Learn more at radiopharmtheranostics.com.
Authorised on behalf of the Radiopharm Theranostics board of directors by Chairman Paul Hopper.
For more information:
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
Paul Hopper
Executive Chairman
P: +61 406 671 515
E: paulhopper@lifescienceportfolio.com
Media
Matt Wright
NWR Communications
P: +61 451 896 420
E: matt@nwrcommunications.com.au
Radiopharm Theranostics
Limited
Suite 1, Level 3, 62 Lygon Street, Carlton South VIC 3053 Australia
ABN: 57 647 877 889