Scancell Holdings PLC (AIM:SCLP, OTC:SCNLF) has reported another encouraging set of mid-stage trial results for its melanoma vaccine candidate iSCIB1+, saying the treatment continues to show better outcomes than today’s standard therapies and is shaping up for late-stage testing next year.
Fresh data from the phase II SCOPE trial suggest the therapy, when combined with the immunotherapy drugs ipilimumab and nivolumab, produced a progression-free survival rate of 74% at 16 months in a genetically defined group of patients.
Progression-free survival measures how long a person lives without their cancer worsening. Scancell contrasted its figure with a published progression-free survival rate of 50% at 11.5 months for the current standard drug combination.
The company said the benefit held up across subgroups that often struggle to respond, including patients with low levels of the PD-L1 protein, those without BRAF mutations and people previously treated with similar checkpoint drugs.
The results helped confirm the use of iSCIB1+, delivered as a needle-free intramuscular injection, for further development in patients with certain human leukocyte antigen types.
These genetic markers influence how the immune system reacts, and Scancell said they represent about 80% of melanoma cases. Out of 50 patients in the relevant cohort, 39 fell within this target group.
Dr Heather Shaw, a principal investigator in the trial, said: “The prolonged progression-free survival demonstrates iSCIB1+ in combination with checkpoint inhibitors has potential to redefine standard of care.”
The wider dataset also showed an overall response rate of 56% in the target population, meaning more than half saw their tumours shrink, while 79% achieved disease control.
Scancell said the strength of patients’ T-cell responses, a type of immune reaction, tracked closely with their clinical outcomes.
Early overall survival data, covering how long patients live after treatment, showed a 14% improvement at 26 months compared with standard therapy.
Dr Nermeen Varawalla, Scancell’s chief medical officer, said the combination therapy was demonstrating “a significant 24% improvement in PFS over standard of care” and stronger performance than its first-generation vaccine, SCIB1.
Discussions with the US Food and Drug Administration and other regulators have been positive, Scancell said, with agreement on the design of a future phase III study and confirmation that progression-free survival is likely to serve as the main measure of success.
The company is in talks with partners and reviewing how to finance the upcoming trial.
Chief executive Dr Phil L’Huillier said the new findings add “further momentum” to preparations for late-stage development in 2026.
He added that the intramuscular approach to delivering the vaccine had shown the most promise, prompting Scancell to discontinue a separate arm of the study that used intradermal injections.
A late-breaking oral presentation on the trial will be given at the ESMO Immuno-Oncology Congress on Thursday, followed by an investor webinar at 2pm GMT.