Presentation (CTI)

OBJECTIVES: Mature overall survival (OS) data refers to clinical trial data with sufficient observed death events to allow for reliable and robust estimation of a treatment’s impact on survival. In Health Technology Assessments (HTAs) conducted by the National Institute for Health and Care Excellence (NICE), OS is the gold standard of clinical evidence. Immature OS data results when the follow-up period of the trial is too short to provide definitive findings. Due to the conflicting needs of early access to treatment while requiring robust evidence, the use of immature OS data is becoming more commonplace in HTA submissions. This study aims to identify trends and considerations in submitted OS data and acceptance by NICE, using non-small cell lung cancer (NSCLC) appraisals as an example.
METHODS: 60 NSCLC appraisals published on the NICE website from 2012-2026 were reviewed. Clinical trial events (deaths) and comments surrounding immature overall survival data, including acceptance and criticisms, were recorded. An analysis was conducted to identify trends in the level of immature OS data (quantified by trial mortality %) being included in NICE submissions and to assess the positive recommendation rate stratified by different levels of OS maturity.
RESULTS: Between January 2012 and May 2026, 63.2% of TAs reported deaths in fewer than 50% of patients. There is a growing trend of HTA submissions using immature OS data, with average maturity declining from 50.8% in 2012-2019 to 35.3% in 2020-2026. TAs with mature overall survival data were more likely to receive positive recommendations (mature (≥50% events): 81.0%, immature (20-50% events): 77.4%, highly immature (<20% events): 40.0%).
CONCLUSIONS: Driven by clinical guidance and the need for timely patient access, NICE HTA submissions increasingly approve medicines based on interim analyses, contributing to a growing reliance on immature OS data.