Radiopharm Theranostics (RADX) finishes U.S. Phase 2b RAD 101 trial enrollment

Rhea-AI Filing Summary

Radiopharm Theranostics completed enrollment in its U.S. Phase 2b imaging trial of RAD 101 for diagnosing recurrent brain metastases from solid tumors. Interim data showed 90% concordance between 18F‑RAD101 and MRI, which is the study’s primary endpoint. A primary endpoint readout is expected in June 2026, and the company plans to advance RAD 101 into a U.S. Phase 3 pivotal trial and engage with the FDA on the regulatory path. RAD 101 targets fatty acid synthase, which is overexpressed in many solid tumors, and has received FDA Fast Track Designation for distinguishing recurrent disease from treatment effects in brain metastases.

Insights

Biotech and clinical-trials analyst

Phase 2b enrollment completion and strong interim concordance de-risk RAD 101’s next clinical steps.

Radiopharm Theranostics has fully enrolled its U.S. Phase 2b trial of RAD 101 in recurrent brain metastases, a setting with high unmet need. The trial includes 30 participants and focuses on diagnostic performance versus contrast-enhanced MRI.

Interim data showed 90% concordance with MRI for the primary endpoint, suggesting RAD 101 tracks closely with the current imaging standard while targeting fatty acid synthase biologically. The asset also benefits from FDA Fast Track Designation, which can facilitate more frequent regulatory interaction.

A primary endpoint readout is expected in June 2026, and the company plans a U.S. pivotal Phase 3 trial. Actual impact will depend on full Phase 2b results and agreement with the FDA on an approvable endpoint and trial design.

Key Figures

Interim concordance: 90% concordance with MRI Trial size: 30 individuals Readout timing: June 2026 +2 more

5 metrics

Interim concordance 90% concordance with MRI Primary endpoint in U.S. Phase 2b RAD 101 trial

Trial size 30 individuals Participants with confirmed recurrent brain metastases in Phase 2b trial

Readout timing June 2026 Expected primary endpoint readout for Phase 2b RAD 101 trial

Fast Track Designation FDA Fast Track For distinguishing recurrent disease from treatment effect in brain metastases

Annual cerebral metastases cases More than 300,000 patients Estimated yearly diagnoses in the United States

Key Terms

Phase 2b imaging trial, Fast Track Designation, brain metastases, fatty acid synthase (FASN), +2 more

6 terms

Phase 2b imaging trial clinical

"the final patient has been dosed in the U.S. Phase 2b imaging trial"

Fast Track Designation regulatory

"RAD 101 received U.S. Food and Drug Administration (FDA) Fast Track Designation"

A "fast track designation" is a process that speeds up the review and approval of a product or project, allowing it to reach the market or be completed more quickly than usual. For investors, it can signal that a product may become available sooner, potentially leading to earlier revenue or benefits, and indicating a priority status that might influence company performance and market opportunities.

brain metastases medical

"for diagnosis of brain metastases"

Cancer cells that have spread from another part of the body to the brain, forming new tumors there. Think of it like weeds from one garden taking root in another; the behavior and treatment needs can change significantly once cancer reaches the brain. For investors, brain metastases matter because they often drive different clinical trial designs, higher healthcare costs, and urgent demand for effective therapies, all of which can materially affect a biotech or healthcare company’s prospects.

fatty acid synthase (FASN) medical

"targets fatty acid synthase (FASN), a multi-enzyme protein that catalyses fatty acid synthesis"

Fatty acid synthase (FASN) is an enzyme that acts like a cellular factory, building long-chain fatty acids from smaller molecular pieces for use in cell membranes, energy storage, and signaling. Investors care because FASN activity is linked to metabolic conditions and certain cancers, making it a potential target for drugs or diagnostics; changes in companies’ progress on FASN-related therapies or tests can affect valuations and risk assessment.

contrast-enhanced Magnetic Resonance Imaging (CE-MRI) medical

"Contrast-enhanced Magnetic Resonance Imaging (CE-MRI) is the preferred method for imaging IMD"

An contrast-enhanced magnetic resonance imaging (ce-MRI) scan is a medical imaging test that uses strong magnets and a safe injectable dye to make organs, blood vessels and abnormal tissue show up more clearly on pictures. For investors, ce-MRI matters because it can change how accurately a condition is diagnosed, how well a treatment’s effects are measured in clinical trials, and therefore influence regulatory decisions, market adoption, and sales for diagnostics, drugs and medical devices — like adding dye to water to reveal hidden leaks.

pivotal trial clinical

"Plans to advance RAD 101 into U.S. Phase 3 pivotal trial"

A pivotal trial is a key test of a new medicine or treatment to see if it works and is safe enough to be approved by health authorities. It's like a final exam for a new product, and passing it is essential for bringing the treatment to the public.

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 16, 2026 titled:

“RAD Completes Enrollment in Phase 2b Trial of RAD 101”

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 Completes Enrollment in Phase 2b Trial of RAD 101

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 16, 2026	By:	/s/ Phillip Hains
		Phillip Hains
		Company Secretary

3

Exhibit 99.1

ASX ANNOUNCEMENT 16 APRIL 2026  

Radiopharm Theranostics Completes Enrollment in U.S. Phase 2b Imaging Trial of RAD 101 for Diagnosis of Brain Metastases

Interim data to date showed 90% concordance with MRI (the primary endpoint)

Clinical trial readout (Primary endpoint) expected in June 2026

Plans to advance RAD 101 into U.S. Phase 3 pivotal trial

Sydney, Australia – 16 April 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, today announced that the final patient has been dosed in the U.S. Phase 2b imaging trial (NCT06777433) evaluating RAD 101 in individuals with confirmed recurrent brain metastases from solid tumors of different origins.

“Dosing the final patient in our most advanced diagnostic program represents an important milestone for Radiopharm and underscores the continued momentum of our radiopharmaceutical pipeline,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “The interim results we have seen to date, demonstrating a high level of concordance with MRI, reinforce our confidence in RAD 101’s potential to address a critical unmet need in the accurate detection of recurrent brain metastases. As we look ahead to the full data readout in June, we are focused on advancing this important program into U.S. pivotal trial and initiating constructive dialogue with the FDA to define the optimal regulatory pathway. We believe RAD 101 has the potential to meaningfully improve clinical decision-making for patients and physicians navigating this challenging disease.”

“I would like to take the opportunity to thank all the patients, families, and caregivers for their trust in our clinical trial. The investigators and the Clinical Center did an amazing job in the recruitment process, and our congratulations go to BAMF HEALTH for leading the table of the top recruiters,” added Mr. Canevari.

RAD 101 is the Company’s novel imaging small molecule that targets fatty acid synthase (FASN), a multi-enzyme protein that catalyses fatty acid synthesis and is overexpressed in many solid tumors, including cerebral metastasis. Targeting FASN activity may allow for the more accurate detection of cancer cells, representing a clinically relevant method for the imaging of brain metastases.

The U.S. multicenter, open-label, single arm Phase 2b clinical trial is evaluating the diagnostic performance of 18F-RAD101 in 30 individuals with confirmed recurrent brain metastases from solid tumors of different origins. The primary objective of the study is concordance between 18F-RAD101 positive lesions and those seen in conventional imaging (MRI with gadolinium) in participants with suspected recurrent brain metastases. RAD 101 received U.S. Food and Drug Administration (FDA) Fast Track Designation to distinguish between recurrent disease and treatment effect of brain metastases originating from solid tumors of different origin, including leptomeningeal disease.

In the U.S. alone, there are more than 300,000 patients diagnosed annually with cerebral metastases. The incidence of Intracranial Metastatic Disease (IMD) continues to increase, in part, due to improvements in systemic therapy resulting in a more durable control of the primary tumor. Contrast-enhanced Magnetic Resonance Imaging (CE-MRI) is the preferred method for imaging IMD, but has limitations, particularly in follow-up surveillance scans to optimise patient care.¹ 

¹ A hybrid [18F]fluoropivalate PET-multiparametric MRI to detect and characterise brain tumour metastases based on a permissive environment for monocarboxylate transport | European Journal of Nuclear Medicine and Molecular Imaging

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

ASX ANNOUNCEMENT 16 APRIL 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, 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 about the RAD 101 trial?

Radiopharm Theranostics announced it has completed enrollment and dosed the final patient in its U.S. Phase 2b imaging trial of RAD 101 for recurrent brain metastases. This marks a key milestone in its most advanced diagnostic program and supports progression toward pivotal development.

How effective is RAD 101 compared with MRI in the Phase 2b trial for RADX?

Interim data from the Phase 2b trial showed RAD 101 achieved 90% concordance with MRI for the primary endpoint. This means RAD 101’s imaging results closely matched conventional contrast-enhanced MRI, supporting its potential as a diagnostic tool in recurrent brain metastases.

When is the primary endpoint readout for Radiopharm’s RAD 101 Phase 2b trial expected?

The primary endpoint readout for the RAD 101 U.S. Phase 2b imaging trial is expected in June 2026. This analysis will focus on concordance between 18F-RAD101 and MRI and will inform Radiopharm’s plan to advance RAD 101 into a U.S. Phase 3 pivotal trial.

What regulatory status does RAD 101 have according to the Radiopharm 6-K?

RAD 101 has received U.S. Food and Drug Administration Fast Track Designation. This designation is for distinguishing recurrent disease from treatment effect in brain metastases from solid tumors, including leptomeningeal disease, and can support more efficient regulatory interactions for Radiopharm.

What is the design of the RAD 101 Phase 2b trial described by Radiopharm Theranostics?

The U.S. Phase 2b trial is a multicenter, open-label, single-arm study evaluating 18F-RAD101 in 30 individuals with confirmed recurrent brain metastases from solid tumors. Its primary objective is concordance between 18F-RAD101–positive lesions and lesions seen on conventional gadolinium-enhanced MRI.

How large is the potential patient population for RAD 101’s brain metastases indication?

Radiopharm notes that in the United States more than 300,000 patients are diagnosed annually with cerebral metastases. Incidence of intracranial metastatic disease is rising, partly due to better systemic therapies, highlighting a substantial population that might benefit from improved brain metastasis imaging.

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 RAD COMPLETES ENROLLMENT IN PHASE 2B TRIAL OF RAD 101 13.5 KB