Scancell Holdings (SCLP) Study update summary

Study Design and Objectives

• SCOPE was a phase II, open-label, multi-cohort study in first-line advanced melanoma, enrolling over 100 patients across 16 UK sites, with cohorts defined by HLA type and treatment generation.

• The study aimed to inform phase III trial design and risk mitigation, focusing on iSCIB1+ in combination with checkpoint inhibitors.

• Patients had unresectable stage III or IV melanoma, ECOG 0-1, measurable lesions, and known HLA status; key exclusions included CNS metastases and recent checkpoint inhibitor exposure.

• iSCIB1+ was tested with nivolumab and ipilimumab, with baseline characteristics comparable to historic controls.

• Cohort 4 introduced accelerated priming and intradermal delivery, but late-stage development will focus on intramuscular administration.

Efficacy Results and Clinical Impact

• iSCIB1+ combined with checkpoint inhibitors achieved 74% progression-free survival (PFS) at 16 months, outperforming standard of care and historic controls.

• Early overall survival (OS) data show a 14% improvement at 26 months compared to standard of care.

• Disease control rate reached 81% in the combined population, with objective response rates of 56–60% in the target HLA group.

• PFS and clinical benefit were consistent across key prognostic subgroups, including BRAF status, PD-L1 status, and prior checkpoint exposure.

• Durable tumor control and strong T-cell responses were demonstrated, with 72–83% of patients mounting a T-cell response to both GP100 and TRP2 epitopes.

Safety and Tolerability

• iSCIB1+ and SCIB1 were generally safe and well-tolerated at doses of 0.4–8 mg, with no increase in checkpoint inhibitor-related toxicities.

• Most adverse events were transient and mild, including elevated liver enzymes, injection site reactions, fatigue, GI, skin, and eye disorders.

• No evidence of increased toxicity or potentiation of adverse events with iSCIB1+ addition.