782TiP Reduced frequency immune checkpoint inhibition in cancers (REFINE): A multi-arm phase II trial testing reduced intensity immunotherapy in different cancers

Abstract

Immune checkpoint inhibitors (ICI) have revolutionised cancer treatment, resulting in long-term durable responses. In advanced disease, ICIs are administered every 2-6 weeks i.v. until cancer progression or unacceptable toxicity, which is often several years’ treatment. Physiological efficacy of anti-PD-1 antibodies (maximal receptor occupancy) is seen at lower doses than those in routine use. Pharmacodynamic studies indicate sustained target occupancy of >70% for at least 2 months, despite half-lives of 2-3 weeks.