Five-year durability in cell and gene therapy: evidence review and implications for payer coverage

Cell and gene therapies (CGTs) offer the potential for durable clinical benefit following a single administration. Although early regulatory approvals were often based on limited follow-up, an increasing number of U.S. Food and Drug Administration (FDA)-approved CGTs now report extended durability data from clinical trials, registries, and real-world evidence (RWE) sources.

This report synthesizes publicly available long-term follow-up (LTFU) evidence for FDA-approved CGTs in the United States, with a focus on durability of clinical benefit and the implications for payer coverage and reimbursement. Long-term efficacy and safety data for marketed CGTs were identified through a review of peer-reviewed publications and publicly available conference abstracts and presentations. As of December 2025, 21 therapies (62%) report follow-up extending to 5 years or longer. The review examines the available durability evidence and explores its relevance to ongoing discussions around durability-related uncertainty and the role of LTFU and real-world evidence in assessing CGT outcomes.

Growing LTFU evidence suggests that durable clinical benefit can be achieved across multiple CGT platforms and disease settings. While uncertainties remain, accumulating data may help reduce durability-related uncertainty and inform payer coverage, reimbursement, and value assessment discussions.