OncoSil Medical has reported encouraging results from an independent formulation study showing that its phosphorus-32 microparticles can be suspended and delivered at substantially higher concentrations than those currently used in commercial practice without increasing the resistance to flow clinicians experience during procedures.
The study, carried out by the Physical Pharmacy Team at the Institut Galien Paris‑Saclay (Université Paris‑Saclay), measured suspension viscosity across eight concentrations from diluent alone up to 150 mg/mL using non‑radioactive microparticles identical in composition and particle size to the clinical product.
The company said all suspensions displayed the expected shear‑thinning behaviour, and, counter to conventional expectations for a particle suspension, viscosity did not rise as particle concentration increased. At the high shear rates encountered during injection, viscosity was essentially the same at every concentration tested. The particle volume fractions remained low throughout, at approximately 6 per cent even at the highest loading.
OncoSil said the findings are meaningful because the device delivers a therapeutic dose of phosphorus‑32 microparticles suspended in a proprietary diluent and the isotope’s 14.27‑day half‑life means activity decays over time. Treatments performed later in a batch’s life therefore require more microparticles to deliver the same target activity. Being able to formulate reliably at higher particle concentrations could give treating centres greater scheduling flexibility and extend the usable dosing window for each manufactured batch.
OncoSil Managing Director and CEO Nigel Lange said, "These independent findings represent an important step in our formulation development program. The rheology data support continued investigation of higher‑concentration formulations and provide a strong rationale for the next phase of testing, which will evaluate injectability. We're encouraged by these results and look forward to building on them as the program advances."
OncoSil Medical, which develops the OncoSil device for targeted intratumoural delivery of phosphorus‑32 in unresectable locally advanced pancreatic cancer, noted that if higher‑concentration formulations are validated through its ongoing development and regulatory processes, they could support a wider dosing and scheduling window from each batch and improve production planning and patient treatment flexibility.
