Radiopharm reports positive RAD301 Phase 1 data

Phase 1 imaging data for RAD301 in pancreatic cancer show favorable safety and tumor-specific uptake, supporting advancement toward Phase 2 development.

Rhea-AI Filing Summary

Radiopharm Theranostics Ltd (RADX) reported positive initial results from a Phase 1 imaging trial of its radiopharmaceutical candidate RAD301 in healthy volunteers and patients with Pancreatic Ductal Adenocarcinoma. RAD301 targets the αvβ6-integrin receptor using Gallium-68, aiming for more tumor-specific imaging in pancreatic cancer.

The trial showed a favorable safety profile and significant, selective tumor uptake in pancreatic cancer metastases, with low background uptake in liver, lung and bowel, which are common metastatic sites. These data support continued clinical development of RAD301, including a potential Phase 2 imaging trial, and reinforce αvβ6-integrin as a promising diagnostic and therapeutic target. RAD301 has previously received FDA Orphan Drug Designation.

Positive

• RAD301 Phase 1 trial shows favorable safety and significant, selective tumor uptake in pancreatic cancer metastases, with low background signal in common metastatic organs, supporting further clinical development and potential Phase 2 imaging studies.

Negative

• None.

Filing Explained

The September 9 Form 6-K’s new effect is procedural: it incorporates the attached September 8 RAD301 announcement into Radiopharm’s active Form F-3 registration statement, updating that registration record without itself reporting a securities transaction.

Key Figures

Phase 1 imaging trial: 1 trial Orphan Drug Designation: 1 designation Clinical pipeline trials: 1 Phase 2 and 5 Phase 1 trials +1 more

4 metrics

Phase 1 imaging trial 1 trial Phase 1 imaging trial of RAD301 in healthy volunteers and PDAC patients

Orphan Drug Designation 1 designation RAD301 has received FDA Orphan Drug Designation

Clinical pipeline trials 1 Phase 2 and 5 Phase 1 trials Company-wide clinical program in various solid tumor cancers

Announcement date September 8, 2026 Date of positive RAD301 Phase 1 data announcement in Sydney, Australia

Key Terms

biodistribution, dosimetry, Pancreatic Ductal Adenocarcinoma, αvβ6-integrin, +2 more

6 terms

biodistribution medical

"designed to evaluate the safety, biodistribution and dosimetry of RAD301"

Biodistribution is the map of where a drug, vaccine, or diagnostic agent travels and accumulates inside the body after administration. Investors care because where a product ends up affects how well it works, what side effects it may cause, and whether regulators will approve it—similar to tracking dye in a plumbing system to find leaks or blockages; unexpected destinations can raise safety, cost, and market-adoption risks.

dosimetry medical

"designed to evaluate the safety, biodistribution and dosimetry of RAD301"

Dosimetry is the measurement and calculation of how much ionizing radiation is absorbed by people, tissues, or devices, similar to a thermostat tracking temperature in different rooms to know where and how much heat is present. Investors should care because accurate dosimetry underpins safety, treatment effectiveness, regulatory approval, and liability for products and services that use radiation—affecting market access, costs, and commercial risk.

Pancreatic Ductal Adenocarcinoma medical

"subjects with Pancreatic Ductal Adenocarcinoma (PDAC)"

A fast-growing cancer that starts in the cells lining the pancreas’ small ducts; it is the most common and aggressive form of pancreatic cancer. It matters to investors because its severity and limited treatment options drive high unmet medical need, large potential markets for effective drugs or diagnostics, and strong sensitivity of company valuations to clinical trial results, regulatory approvals, or changes in treatment guidelines—similar to how fixing a main leak can prevent major damage in a building.

αvβ6-integrin medical

"RAD301 ... targets αvβ6-integrin, a cellular marker for tumor invasion"

A cell-surface receptor made of two protein subunits, alpha-v and beta-6, that helps cells stick to their surroundings and send signals; think of it as a specific lock on some cells’ surfaces. It matters to investors because αvβ6-integrin is often increased in certain cancers and fibrotic diseases, so drugs or diagnostics that target it can be the basis for clinical trials, patents, partnerships, and potential commercial products.

Orphan Drug Designation regulatory

"RAD 301 has previously received Orphan Drug Designation (ODD) from the FDA"

Orphan drug designation is a special status given to medicines developed to treat rare diseases affecting only a small number of people. This status often provides benefits like faster approval processes and financial incentives, making it more attractive for companies to develop these drugs. For investors, it signals potential for exclusive market rights and reduced competition, which can impact the drug’s profitability.

theranostic medical

"potentially as a theranostic pair"

A theranostic is a single medical approach or agent that combines diagnosis and treatment—using a test or imaging step to find patients likely to benefit, then delivering a targeted therapy tied to that same marker. For investors, theranostics can speed development, lower the chance of failed trials and concentrate sales on the right patients, like a smart key that both locates the correct lock and opens it, potentially improving clinical and commercial success.

FAQ

What did Radiopharm Theranostics (RADX) announce about the RAD301 Phase 1 trial?

Radiopharm Theranostics announced that the Phase 1 imaging trial of RAD301 in healthy volunteers and Pancreatic Ductal Adenocarcinoma patients showed a favorable safety profile and significant, selective tumor uptake, supporting continued clinical development.

How did RAD301 perform in imaging pancreatic cancer in the Phase 1 study for RADX?

In the Phase 1 study, RAD301 demonstrated significant and selective tumor uptake in pancreatic cancer metastases and low background uptake in liver, lung and bowel, suggesting improved ability to distinguish metastatic lesions from normal tissue.

What is RAD301 and how does it work for Radiopharm Theranostics (RADX)?

RAD301 is a peptide-based molecule labeled with Gallium-68 that targets the αvβ6-integrin receptor, which is highly expressed on most pancreatic carcinoma cells. This makes it a potential tool for more tumor-specific imaging and future theranostic applications.

Does RAD301 have any regulatory designations mentioned by RADX?

Yes. RAD301 has previously received Orphan Drug Designation from the U.S. Food and Drug Administration, reflecting its development for a condition with high unmet medical need such as pancreatic cancer.

What are the next potential clinical steps for RAD301 at Radiopharm Theranostics (RADX)?

Based on the Phase 1 results, the company states there is a rationale for a future Phase 2 imaging trial of RAD301 in pancreatic cancer, to further evaluate its clinical utility and potential theranostic applications.

What broader clinical pipeline does Radiopharm Theranostics (RADX) report?

Radiopharm Theranostics reports a pipeline including one Phase 2 and five Phase 1 trials across various solid tumors such as lung, breast, prostate and brain cancers, using peptides, small molecules and monoclonal antibodies.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/09/2026 - 08:00 AM Accepted by SEC EDGAR 09/09/2026 - 08:00 AM Learn about SEC filing dates

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 September 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 September 9, 2026 titled:

“RAD Announces Positive Data from RAD301 P1 Imaging 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 Number		Description
99.1		RAD Announces Positive Data from RAD301 P1 Imaging 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: September 9, 2026	By:	/s/ Amritha Sushil
		Amritha Sushil
		Company Secretary

3

Exhibit 99.1

ASX ANNOUNCEMENT
September 9, 2026

Radiopharm Theranostics Announces Positive Data from the Phase 1 Imaging Trial of RAD301 in Patients with Pancreatic Ductal Adenocarcinoma

Positive safety and favourable biodistribution seen in all subjects dosed

Imaging data in all evaluable pancreatic cancer patients demonstrated significant tumor uptake

Data support the targeting potential of RAD301 and continuation of its clinical development

Sydney, Australia – 8 September 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 positive data from the Phase 1 imaging trial designed to evaluate the safety, biodistribution and dosimetry of RAD301 in healthy volunteers and subjects with Pancreatic Ductal Adenocarcinoma (PDAC).

RAD301 is a peptide-based molecule bound to Gallium-68 (Ga-68) that targets αvβ6-integrin, a cellular marker for tumor invasion and metastatic growth, the expression of which correlates with decreased survival in several carcinomas. The αvβ6-integrin receptor is found in high density on most pancreatic carcinoma cells, making it an attractive diagnostic and therapeutic target. RAD 301 has previously received Orphan Drug Designation (ODD) from the FDA.

“These data are an important step forward for patients suffering from advanced pancreatic cancer, as RAD301 has demonstrated significant and selective tumor uptake in metastatic lesions,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “Given the limited imaging and treatment options available for patients with PDAC, these findings highlight the potential role of RAD301 in improving disease detection, patient selection, and future theranostic applications. Pancreatic cancer remains a challenging disease to image, and conventional approaches such as FDG PET are limited by variable tumor biology and non-specific uptake. The results from this Phase 1 study support the potential of αvβ6-integrin-targeted imaging to provide a more tumor-specific approach to detecting pancreatic cancer, further supporting the advancement of RAD 301 into Phase 2 development.”

Data from the Phase 1 trial of RAD301 demonstrated a favorable safety profile in all evaluable participants. Additionally, RAD301 had favorable biodistribution along with significant tumor uptake in pancreatic cancer metastases, consistent with initial results from the first five patients evaluated. The results showed significant and selective tumor uptake in pancreatic cancer metastases, which supports the potential of αvβ6-integrin as a target for future therapeutic development and potentially as a theranostic pair.. Importantly, the low background uptake observed in liver, lung and bowel — the sites where pancreatic cancer most often spreads — supports the potential of RAD301 to distinguish metastatic lesions from surrounding normal tissue. The unmet medical need in the earlier stages of disease and the high mortality of the disease provide a rationale for a future Phase 2 imaging trial of RAD301.

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

ASX ANNOUNCEMENT
September 9, 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 Radiopharm Theranostics Board of Directors by Executive Chairman Paul Hopper.

For more information:

Investors:

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

Media:

Matt Wright
NWR Communications
P: +61 451 896 420
E: matt@nwrcommunications.com.au

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

Filing Exhibits & Attachments

1 document

Press Releases

• EX-99.1 RAD ANNOUNCES POSITIVE DATA FROM RAD301 P1 IMAGING TRIAL 11.2 KB