Key highlights

  • Starpharma (ASX:SPL) shares fell 25.33% to $0.56 during the Trading session on 20 October 2026.
  • The company announced it increased its Equity interest in Petalion Therapeutics from 22.5% to 66%.
  • Starpharma will contribute up to A$5.0 million, made up of A$3.0 million in cash and the balance in R&D services.

During the trading session on 20 October 2026, shares of Starpharma Holdings Limited (ASX:SPL) fell 25.33% to $0.56. The company also announced that day that it had increased its equity interest in Petalion Therapeutics from 22.5% to 66%, securing majority ownership and governance control of a fibroblast activation protein (FAP)-targeted oncology program. The two items are reported as stated and are not linked in this article.

About Starpharma Holdings Limited

Starpharma is a biotechnology company advancing dendrimer technology, with shares quoted on the ASX and its American depositary receipts on the US OTC market under SPHRY. Its DEP drug delivery platform is applied to oncology programs. Petalion was established in 2024 as an asset-centric company focused on a single FAP-targeted oncology program using Starpharma’s DEP dendrimer platform.

Transaction terms

Following completion of the initial R&D stage, Starpharma elected to increase its ownership before the program enters its next phase. Starpharma will hold 66% of Petalion, Medicxi will retain 30%, and 4% will remain with Petalion advisers.

Starpharma will contribute A$3.0 million in cash and up to A$2.0 million in R&D services. The cash will be funded from the allocation for new R&D pipeline opportunities in its recent Capital raise, and the company says sufficient funds remain in that allocation to progress other early-stage targeted oncology assets.

Governance and structure

Starpharma will appoint two directors, Medicxi will retain one board position, and the Starpharma chief executive will serve as chair. Petalion will become a UK-incorporated Subsidiary of Starpharma Holdings Limited. Starpharma will lead operations and provide its dendrimer, conjugation and development capabilities, while Medicxi continues to provide oncology-development and Investment expertise.

The FAP-targeted program

FAP is highly expressed in the tumour microenvironment across many solid tumours, with relatively limited expression in healthy tissue, and the company describes it as a pan-cancer target relevant to cancers such as pancreatic, lung and breast. Petalion’s approach applies the DEP platform to a FAP-targeted dendrimer-drug conjugate.

Initial research supported progression into further optimisation and lead candidate selection. The next phase will generate the data required to select a lead candidate and define the development and partnering pathway, with the aim of bringing an asset into the clinic. The company will host an online CEO briefing at 12:00 noon AEDT on Wednesday, 21 October 2026.

Sector backdrop

Oncology is among the most active areas of drug development, and targeted conjugates that deliver cytotoxic payloads to tumour-associated proteins are a growing class. Early-stage programs generally take many years and substantial capital to reach clinical proof of concept, and few candidates advance to approval.

Smaller companies often use partnerships and joint structures with specialist investors to share costs and expertise.

Risks shareholders should weigh

The program is at a preclinical stage, with lead candidate selection still to occur. There is no certainty that a candidate will be selected, enter the clinic or demonstrate safety and efficacy. FAP-targeted approaches face scientific and competitive uncertainty.

Starpharma’s additional commitment of up to A$5.0 million reduces funds available for other uses, and further funding for later development stages is not described. Consolidating a majority holding adds operational responsibility. At $0.56, the 25.33% fall on 20 October 2026 illustrates the Volatility that can affect biotechnology shares.

What’s next

The next value-inflection point named in the announcement is lead candidate selection and the definition of the subsequent development and partnering pathway. The CEO briefing and Q&A is scheduled for 12:00 noon AEDT on Wednesday, 21 October 2026.