Scancell has linked iSCIB1+ to a 69% response rate in advanced melanoma, leading the British biotech to advance the next-generation cancer vaccine candidate rather than its older sibling.
The phase 2 study enrolled patients with advanced melanoma to receive either SCIB1 or iSCIB1+ on top of Bristol Myers Squibb’s aging checkpoint inhibitors Opdivo and Yervoy. Both Scancell candidates are designed to turn the immune system against tumors. The biotech modified SCIB1 to create iSCIB1+, resulting in a candidate intended to work in a wider range of melanoma patients.
Tuesday, Scancell reported that the vaccines showed similar safety and efficacy in a phase 2 trial. The overall response rates in the first-line SCIB1 and iSCIB1+ cohorts were 68.4% and 68.9%, respectively. With little to choose between the candidates, Scancell picked iSCIB1+ for further development because it is suitable for use in about 80% of patients compared to just 35% to 40% for SCIB1.
The biotech pooled data on SCIB1 and iSCIB1+ for a cross-trial comparison with BMS’ CheckMate-067 study. After 22 months, the rate of progression-free survival (PFS) in the pooled vaccine analysis was 69%. The result is a more than 20 percentage point improvement on the historical control, Scancell said.
Further updates from the phase 2 trial are scheduled for later this year. Scancell plans to publish PFS and early overall survival data in the fourth quarter. Data from a cohort of patients who received iSCIB1+ on an accelerated dosing schedule are due by the end of the year.
Scancell is now planning to take iSCIB1+ into a phase 2b/3 trial in patients with unresectable melanoma, although the study start is dependent on the biotech inking a deal or securing financing. The company is also assessing the potential to run a second study in patients with resectable tumors and, beyond that, sees a potential opportunity to establish iSCIB1+ as a preventive vaccine in at-risk groups.