Radiopharm Theranostics (NASDAQ: RADX) lifts JV stake to 87.5% ownership

Rhea-AI Filing Summary

Radiopharm Theranostics Limited reports that it has increased its ownership stake in Radiopharm Ventures, LLC, its joint venture with The University of Texas MD Anderson Cancer Center, from 75% to 87.5%. The joint venture is focused on developing cancer radiopharmaceuticals and has shown promising progress in its therapeutic pipeline.

The lead asset, Betabart (RV01), a 177Lu‑labelled monoclonal antibody targeting the B7H3 immune checkpoint protein, received Investigational New Drug clearance from the U.S. Food and Drug Administration in July 2025. The first patient in the Phase 1 dose‑escalation therapeutic trial is expected to be dosed in Q1 2026. Two additional preclinical candidates have also delivered early positive results and are advancing toward final candidate selection for use across multiple solid tumor types.

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Biotech industry analyst

Radiopharm raises its JV stake as lead radiopharma asset enters human trials.

Radiopharm Theranostics has increased its ownership in Radiopharm Ventures, LLC from 75% to 87.5%, deepening its economic exposure to a pipeline being developed with MD Anderson Cancer Center. This signals confidence in the joint venture’s oncology programs, particularly in radiopharmaceuticals targeting solid tumors.

The lead candidate, Betabart (RV01), is a 177Lu‑labelled monoclonal antibody against the B7H3 immune checkpoint protein, which the company notes is commonly overexpressed in many cancers while rarely seen in healthy tissue. It received U.S. FDA Investigational New Drug clearance in July 2025, and the first patient in a Phase 1 dose‑escalation therapeutic study is expected to be dosed in Q1 2026.

Two additional preclinical assets in the joint venture have shown early positive results and are moving toward final candidate selection. Overall, the development progress and higher ownership consolidate Radiopharm’s stake in a focused radiopharmaceutical portfolio, though ultimate impact will depend on clinical data from Betabart and subsequent pipeline readouts.

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 January 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 January 12, 2026 titled:

“RAD Increases Ownership in Radiopharm Ventures to 87.5%”

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 Increases Ownership in Radiopharm Ventures to 87.5%

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: January 12, 2026	By:	/s/ Phillip Hains
		Phillip Hains
		Company Secretary

3

 Exhibit 99.1

ASX ANNOUNCEMENT
12 JANUARY 2026

RAD Increases Ownership in Radiopharm Ventures to 87.5%

● Radiopharm Ventures, LLC, is a joint venture created in 2022 between MD Anderson Cancer Center and Radiopharm Theranostics

● Leading candidate Betabart, a monoclonal antibody targeting B7H3, has received FDA IND clearance for a Phase I therapeutic trial in multiple solid tumors expected to dose the first patient in Q1 2026

● First clinical trial globally targeting B7H3 with a systemic radiopharmaceutical

● Two additional preclinical Radiopharm Ventures’ assets show early positive results with plans to move to final candidate selection in 2026

Sydney, Australia – 12 January 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 needs, is pleased to announce that it has increased its ownership stake in Radiopharm Ventures, LLC, a joint venture created with The University of Texas MD Anderson Cancer Center (MDACC), from 75% to 87.5%.

Radiopharm’s decision to increase the ownership percentage comes as the joint venture continues to show promising progress in its cancer therapeutic pipeline, including the advancement of its leading B7H3 candidate and other preclinical assets.

B7H3 is an immune checkpoint protein that is very infrequently seen in healthy cells but is consistently overexpressed in the majority of cancer tissues. High expression of B7H3 in cancer is associated with greater tumor size and lymphatic invasion.

Riccardo Canevari, CEO & Managing Director of Radiopharm, commented: "We are very encouraged by the progress to date within Radiopharm Ventures. Now is an exciting time to increase our ownership in the joint venture, as we will soon have first-in-human results of Betabart (RV01) from our dose escalating therapeutic Phase I study. We remain confident in the potential value of this program and its potential to benefit patients battling a multitude of solid tumor cancers.”

The lead candidate monoclonal antibody (mAb) radiolabelled with ¹⁷⁷Lu, Betabart, targets B7H3 and successfully received Investigational New Drug clearance in July 2025 by the U.S. Food and Drug Administration. The first patient in this Phase 1 therapeutic trial is expected to be dosed in Q1 2026, with a number of centers already activated.

Additionally, two other preclinical candidates have demonstrated early positive results and have progressed towards final candidate selection, with potential applications across multiple solid tumor types.

Radiopharm and MDACC launched Radiopharm Ventures, LLC in September 2022 to develop novel radiopharmaceutical products for cancer treatment. The joint venture leverages MD Anderson’s expertise in antigen discovery and molecular imaging alongside Radiopharm’s capabilities in developing targeted radiopharmaceutical therapies.

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

ASX ANNOUNCEMENT
12 JANUARY 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 four Phase 1 trials in a variety of solid tumor cancers, including lung, breast, and brain metastases. Learn more at radiopharmtheranostics.com.

Authorized on behalf of the Radiopharm Theranostics Board of Directors by Executive 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

Follow Radiopharm Theranostics:

Website – https://radiopharmtheranostics.com/
Twitter – https://twitter.com/TeamRadiopharm
Linked In – 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 in this Form 6-K?

Radiopharm Theranostics announced that it increased its ownership in Radiopharm Ventures, LLC, its joint venture with The University of Texas MD Anderson Cancer Center, from 75% to 87.5% and highlighted progress in the joint venture’s oncology radiopharmaceutical pipeline.

What is Radiopharm Ventures, the joint venture mentioned by Radiopharm Theranostics (RADX)?

Radiopharm Ventures, LLC is a joint venture launched in September 2022 by Radiopharm Theranostics and MD Anderson Cancer Center to develop novel radiopharmaceutical products for cancer treatment, combining MD Anderson’s antigen discovery and imaging expertise with Radiopharm’s radiopharmaceutical development capabilities.

Who is Betabart (RV01) and what stage of development is it in for Radiopharm Theranostics (RADX)?

Betabart (RV01) is the lead monoclonal antibody radiolabelled with 177Lu that targets the B7H3 immune checkpoint protein. It received U.S. FDA Investigational New Drug clearance in July 2025, and the first patient in its Phase 1 dose‑escalation therapeutic trial is expected to be dosed in Q1 2026.

Why is the B7H3 target important in Radiopharm Theranostics’ (RADX) pipeline?

The company explains that B7H3 is an immune checkpoint protein that is rarely seen in healthy cells but is consistently overexpressed in most cancer tissues, with high expression associated with larger tumor size and lymphatic invasion, making it a compelling target for cancer radiopharmaceuticals.

What other pipeline assets are mentioned by Radiopharm Theranostics (RADX) in this update?

In addition to Betabart (RV01), Radiopharm notes that two other preclinical candidates within Radiopharm Ventures have shown early positive results and have progressed toward final candidate selection for potential use across multiple solid tumor types.

How does this development fit into Radiopharm Theranostics’ (RADX) broader clinical program?

Radiopharm describes itself as a clinical‑stage radiotherapeutics company with a pipeline spanning peptides, small molecules, and monoclonal antibodies, and notes that its overall clinical program includes one Phase 2 and four Phase 1 trials in various solid tumor cancers, including lung, breast, and brain metastases.