Denmark's IO Biotech announced its off-the-shelf therapeutic cancer vaccine Cylembio (IO102-IO103) failed to meet the primary progression-free survival (PFS) endpoint in the Phase III IOB-013 trial combining it with pembrolizumab for untreated metastatic melanoma (HR=0.77, P=0.056). The vaccine targeting PD-L1 and IDO1-positive cells showed numerical but not statistically significant PFS improvement (19.4 vs 11.0 months), though clinically meaningful benefit emerged in PD-L1-negative subgroups (16.6 vs 3.0 months, HR=0.54).
Despite the miss, IO Biotech plans discussions with US health authorities about potential regulatory pathways based on encouraging overall survival trends (HR=0.79) and a manageable 56% injection-site reaction rate with no new safety signals. The company will present detailed results at upcoming conferences while continuing development of its T-cell stimulating vaccine platform for other solid tumours. The outcome contrasts with recent successes of mRNA cancer vaccines but confirms the challenges of combining therapeutic vaccines with immune checkpoint inhibitors.
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