Highlights

• Starpharma shares rose 4.23% to AUD 0.74 during the morning session on 2 July 2026 after two favourable DEP radiopharmaceutical updates.

• DEP HER2-Lu showed favourable biodistribution, low kidney accumulation and encouraging anti-tumour activity in preclinical models.

• The company plans to move DEP HER2-Lu into a first-in-human Phase 1 study in H2 CY2026.

• Starpharma filed a new patent application covering the use of DEP dendrimer technology in radioligand therapy.

• Preclinical findings across HER2, PSMA and EGFR support DEP as a modular radiopharmaceutical platform.

Shares of Starpharma Holdings Ltd (ASX:SPL) advanced 4.23% to AUD 0.74 during the morning session on 2 July 2026, after the company released two updates linked to its proprietary DEP radiopharmaceutical platform. The stock has also delivered a notable 722.22% gain over the past year, with investor attention today centred on positive preclinical data for DEP HER2-lutetium (DEP HER2-Lu) and a new patent application supporting the use of DEP technology in radioligand therapy.

Starpharma is a biotechnology company focused on dendrimer-based drug delivery technology. Its proprietary DEP platform is designed to improve the delivery, biodistribution and targeting of therapeutic payloads. The company has more than two decades of experience in dendrimer technology and has built a portfolio that includes three clinical-stage DEP assets, preclinical radiopharmaceutical assets, research collaborations and three commercially marketed over-the-counter products. Dendrimers are nanoscale synthetic molecules with features such as branching structure, water solubility and polyvalency, which the company applies across pharmaceutical and medical uses.

Positive DEP HER2-Lu Data Draws Investor Attention

The main focus of Starpharma’s latest update was the release of preclinical data for DEP HER2-Lu, its HER2-targeted radiotherapy candidate. The company reported that the candidate demonstrated strong tumour uptake and retention, low kidney accumulation and a short blood circulation time in preclinical HER2-positive cancer models.

These characteristics are important in radioligand therapy because the aim is to deliver radiation directly to cancer cells while reducing exposure to healthy organs. Starpharma said the DEP dendrimer component improved biodistribution compared with a non-DEP HER2-targeting construct, supporting its strategy of using DEP technology to enhance radiopharmaceutical delivery.

The company also reported that DEP HER2-Lu achieved statistically significant anti-tumour activity and survival benefit in preclinical models. In those models, the effects were comparable to Enhertu, an approved HER2-directed antibody drug conjugate.

Phase 1 Entry Planned for H2 CY2026

The preclinical results are being used to support the planned progression of DEP HER2-Lu into a first-in-human Phase 1 clinical study in H2 CY2026.

Starpharma said Phase 1 preparations are well advanced, and the planned study is expected to initially enrol up to 15 patients with advanced HER2-positive cancers. The study will assess safety, tolerability, pharmacokinetics, biodistribution and organ radiation dosimetry, providing the first clinical evaluation of the DEP HER2-Lu candidate.

The company also noted that in April 2026, the U.S. FDA indicated that Starpharma’s existing preclinical data package, together with data from the planned first-in-human study, should be adequate to support future U.S. clinical studies under an Investigational New Drug application. This feedback supports the company’s proposed development pathway.

HER2 Cancer Opportunity Moves Into Focus

DEP HER2-Lu is initially being developed for patients with advanced HER2-positive cancers, including gastric and gastro-oesophageal junction cancers, as well as other HER2-expressing advanced cancers after prior HER2-targeted therapy.

The company highlighted a significant treatment need in this area, noting that an estimated 75–80% of gastric cancer patients treated with Enhertu may require next-line therapy within 12 months. Starpharma also stated that the combined value of the HER2-positive gastric and gastro-oesophageal junction cancer market, together with the HER2-positive breast cancer market, is currently US$12.6 billion and is expected to reach US$17 billion by 2030.

While the initial Phase 1 study is expected to focus on HER2-positive cancers, Starpharma also observed anti-tumour activity and survival benefit in a HER2-low expressing preclinical model. The company said these findings may support future evaluation across a broader HER2-expressing patient population.

Biodistribution Profile Supports Differentiation

A key theme in Starpharma’s announcement was the biodistribution profile of DEP HER2-Lu.

In a HER2-positive SKOV3 tumour mouse model, DEP HER2-Lu showed tumour accumulation and lower kidney exposure compared with a radiolabelled HER2-targeting VHH without dendrimer, known as HER2-VHH-Lu. The comparison was shown at 4 hours and 5 days post-dose, with mice dosed with 15 MBq of radioactivity.

Starpharma also reported that DEP HER2-Lu maintained high tumour levels relative to blood and major organs from 48 hours to 12 days post-dose. At 12 days, tumour radioactivity was approximately 150 times greater than blood levels.

The company said this profile is important because kidney and blood exposure can limit dosing and clinical utility in radioligand therapy. DEP HER2-Lu was also reported to be well tolerated in preclinical studies. A formal GLP toxicology study using non-radiolabelled DEP HER2 showed no abnormal clinical findings and no significant changes in haematology parameters.

Anti-Tumour Activity and Survival Benefit Reported

Starpharma said the favourable biodistribution profile translated into anti-tumour activity and survival benefit in a HER2-positive cancer model.

The preclinical study involved mice dosed intravenously on day 0, with n=8 per group. Tumour volume curves were displayed until the first mouse in each group reached the volume endpoint of 1,500 mm³, while the study was terminated on Day 57.

The company reported that DEP HER2-Lu demonstrated statistically significant anti-tumour activity and survival benefit compared with vehicle and HER2-VHH-Lu. At Day 57, the company noted 50% survival for DEP HER2-Lu compared with 12.5% survival for Enhertu in the preclinical model.

Patent Filing Strengthens Platform Position

Alongside the DEP HER2-Lu data, Starpharma announced the filing of a new patent application covering the use of its DEP dendrimer technology in radioligand therapy.

The company said the patent application strengthens its intellectual property position in radiopharmaceutical drug delivery and is expected to support protection of DEP radiopharmaceutical approaches across multiple targets.

This is important for Starpharma’s broader platform strategy, as the DEP technology is being evaluated across multiple oncology targets, including HER2, PSMA and EGFR. According to the company, consistent data across these targets support DEP as a modular and broadly applicable radiopharmaceutical platform.

Radiopharmaceutical Market Creates Partnering Potential

Starpharma noted that radiopharmaceuticals are one of the fastest-growing areas of precision oncology. According to the company, the global radiopharmaceutical market is valued at around US$8 billion and is expected to grow to approximately US$15 billion by 2030.

The company said the sector is attracting significant interest from global pharmaceutical companies, supported by clinical outcomes, investment activity and partnering momentum.

Starpharma believes the DEP platform may help address key limitations seen in existing radioligand approaches. Conventional methods can face challenges such as high kidney uptake in peptides and fragments, or prolonged systemic exposure in antibody-based approaches. DEP is designed to combine targeted delivery with tuneable pharmacokinetics.

DEP Platform Could Support Multiple Oncology Programs

The company’s broader update suggests that DEP may have applications beyond a single radiopharmaceutical candidate.

Starpharma stated that the platform’s consistent biodistribution profile across HER2, PSMA and EGFR highlights its modular nature and applicability across different tumour types and targeting strategies. This could support the development of multiple differentiated radiopharmaceutical assets and create opportunities for parallel partnering programs across oncology targets.

The company continues to evaluate partnering opportunities with specialist radiopharmaceutical and oncology companies to leverage DEP technology in this evolving area.

Management Highlights Clinical and Partnering Pathway

Starpharma Chief Executive Officer Cheryl Maley said the DEP HER2-Lu data represent an important milestone and provide preclinical support for moving the program toward first-in-human evaluation. She highlighted the balance between tumour uptake and retention, along with low kidney accumulation, as a key point of differentiation.

Management also said the patent filing supports Starpharma’s strategy to generate value through development and partnering of multiple DEP radiopharmaceutical programs.

Professor Tony Lahoutte, Head of the Department of Nuclear Medicine at University Hospital Brussel and Head of Molecular Imaging and Therapy Research at Vrije Universiteit Brussel, also commented on the data. He pointed to the biodistribution profile, including tumour uptake, retention and low kidney accumulation, as supporting further clinical evaluation of DEP HER2-Lu.

Investor Webinar Scheduled

Starpharma will hold an investor webinar on Tuesday, 7 July 2026 at 2:00pm AEST to discuss the DEP HER2-Lu preclinical data, broader radiopharmaceutical platform progress and the related patent update.

The webinar is expected to provide further detail on the company’s development plans as it prepares for the first-in-human Phase 1 study in H2 CY2026.

What This Means for Investors

Starpharma’s latest update combines two important elements: preclinical progress and intellectual property expansion. The positive DEP HER2-Lu data support the planned move into a first-in-human Phase 1 study in H2 CY2026, while the new patent application adds protection around the broader use of DEP technology in radioligand therapy. The update also positions the company within a growing radiopharmaceutical market, where Starpharma is seeking potential partnering opportunities across multiple oncology targets. Investors are likely to watch the Phase 1 timeline, future regulatory steps, partnering activity and further DEP platform data.

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