Starpharma (ASX:SPL) has reported encouraging preclinical results for its DEP HER2 targeted radiotherapy candidate, DEP HER2 Lu, that pave the way for a planned first-in-human Phase 1 study in the second half of 2026.
The company says the construct combined a HER2-targeting nanobody, its proprietary DEP dendrimer platform, and the therapeutic radioisotope lutetium-177 to deliver radiation selectively to tumours while limiting exposure to healthy organs, particularly the kidneys.
In animal models, the DEP HER2 Lu construct showed strong tumour uptake and prolonged tumour retention with low kidney accumulation and short blood circulation time.
The company said ex vivo biodistribution data in a HER2-positive SKOV3 tumour mouse model showed high tumour radioactivity relative to blood and major organs from 48 hours to 12 days post-dose, with tumour radioactivity about 150 times greater than blood levels at day 12. The favourable biodistribution translated into statistically significant anti-tumour activity and a survival benefit in preclinical models.
Professor Tony Lahoutte at University Hospital UZ Brussel and Vrije Universiteit Brussel described the data as compelling and emphasised the importance of the biodistribution profile.
He said, "The preclinical data for Starpharma’s DEP HER2-Lu are compelling, particularly the biodistribution profile, which demonstrates strong tumour uptake and retention together with low kidney accumulation.
“In radioligand therapy, off-target exposure, especially to the kidneys and blood, can limit dosing and clinical utility. The preclinical data for DEP HER2-Lu clearly show a favourable biodistribution profile that also achieves encouraging anti-tumour activity and survival benefit.
“These data support further clinical evaluation of DEP HER2-Lu and I am excited to see the translation of these data in the planned first-in-human study.”
Starpharma CEO Cheryl Maley added, “These data represent an important milestone for DEP HER2-Lu and provide strong preclinical support for advancing the program toward first-in-human evaluation. The key point of differentiation is the biodistribution profile – strong tumour uptake and retention combined with low kidney accumulation – which is the balance we believe is needed to improve the therapeutic potential of radioligand therapy.
“Importantly, the results also support the broader potential of Starpharma’s DEP platform in radiopharmaceuticals. With supportive FDA feedback and Phase 1 preparations well advanced, DEP HER2-Lu is positioned to generate important clinical data in advanced HER2-positive cancers from H2 CY2026.
“I am incredibly proud of the team and their diligent efforts to achieve the optimal profile for the DEP® HER2-Lu radiotherapeutic construct. Their intense focus to get the best outcome for patients has been very impressive.”
Starpharma said it expects the first-in-human Phase 1 study to commence in the second half of 2026 and to initially enrol up to 15 patients with advanced HER2-positive cancers to assess safety, tolerability, pharmacokinetics, biodistribution, and organ radiation dosimetry.
