COMPARISON OF 5-YEAR SURVIVAL AND ESTIMATED LIFE YEARS BETWEEN TWO DATA CUTS OF STUDY 309/KEYNOTE-775
Author(s)
Qi Zhao, MPH, MS, MD1, Iulia Dunnett, Masters2, Elizabeth Hancock, MSc3, David Trueman, BSc, MSc3, Carolyn Bodnar, BSc, MA4;
1Eisai Inc., Director, Nutley, NJ, USA, 2Source Health Econommics, London, United Kingdom, 3Source Health Economics, London, United Kingdom, 4Eisai Limited, Hatfield, United Kingdom
1Eisai Inc., Director, Nutley, NJ, USA, 2Source Health Econommics, London, United Kingdom, 3Source Health Economics, London, United Kingdom, 4Eisai Limited, Hatfield, United Kingdom
OBJECTIVES: • To compare estimates of 5-year survival and mean life years (LY) between data cut-offs (DCO) of Study 309/KEYNOTE-775 - a Phase 3 trial comparing lenvatinib plus pembrolizumab (LEN+PEM) with treatment of physician’s choice (TPC) in patients with advanced endometrial cancer previously treated with ≥1 platinum-based chemotherapy regimens. • The comparison is informed by a prior cost-effectiveness analysis (USA & China) that fitted parametric survival curves to overall survival (OS) data from the March 2022 DCO; the OS hazard ratio (HR) for this DCO was 0.65 (95% confidence interval [CI]: 0.55,0.77) for LEN+PEM versus TPC. • In the February 2025 DCO, the OS HR was 0.66 (95% CI: 0.57,0.77); maximum follow-up was ~6 years.
METHODS: • Six parametric survival distributions (exponential, generalized gamma, Gompertz, log-logistic, log-normal, Weibull) were fitted to OS data for LEN+PEM and TPC at both DCOs; all distribution results are presented. • Patient-level data were available for the 2022 DCO; recently published Kaplan-Meier data were digitized for the 2025 DCO.
RESULTS: • 2022 DCO: estimated 5-year survival was 10-17% for LEN+PEM, 2-6% for TPC. • 2025 DCO: observed OS Kaplan-Meier estimator at 5 years was 20% for LEN+PEM, 7% for TPC. • Total LYs were 2.2-3.3 for LEN+PEM and 1.4-1.8 for TPC using the 2022 DCO; 2.7-4.3 for LEN+PEM and 1.6-1.9 for TPC using the 2025 DCO. • Using the log-normal distribution for LEN+PEM and log-logistic for TPC (selected in previous CEA based on statistical fit), incremental LYs were 1.4 for the 2022 DCO and 1.7 for the 2025 DCO.
CONCLUSIONS: • Observed 5-year survival for LEN+PEM and TPC at the 2025 DCO was higher than estimates from parametric curves based on the 2022 DCO. • Incremental LYs increased between DCOs, and the OS HR remains consistent, suggesting no treatment effect waning for LEN+PEM versus TPC over 6 years.
METHODS: • Six parametric survival distributions (exponential, generalized gamma, Gompertz, log-logistic, log-normal, Weibull) were fitted to OS data for LEN+PEM and TPC at both DCOs; all distribution results are presented. • Patient-level data were available for the 2022 DCO; recently published Kaplan-Meier data were digitized for the 2025 DCO.
RESULTS: • 2022 DCO: estimated 5-year survival was 10-17% for LEN+PEM, 2-6% for TPC. • 2025 DCO: observed OS Kaplan-Meier estimator at 5 years was 20% for LEN+PEM, 7% for TPC. • Total LYs were 2.2-3.3 for LEN+PEM and 1.4-1.8 for TPC using the 2022 DCO; 2.7-4.3 for LEN+PEM and 1.6-1.9 for TPC using the 2025 DCO. • Using the log-normal distribution for LEN+PEM and log-logistic for TPC (selected in previous CEA based on statistical fit), incremental LYs were 1.4 for the 2022 DCO and 1.7 for the 2025 DCO.
CONCLUSIONS: • Observed 5-year survival for LEN+PEM and TPC at the 2025 DCO was higher than estimates from parametric curves based on the 2022 DCO. • Incremental LYs increased between DCOs, and the OS HR remains consistent, suggesting no treatment effect waning for LEN+PEM versus TPC over 6 years.
Conference/Value in Health Info
2026-05, ISPOR 2026, Philadelphia, PA, USA
Value in Health, Volume 29, Issue S6
Code
CO29
Topic
Clinical Outcomes
Topic Subcategory
Comparative Effectiveness or Efficacy, Relating Intermediate to Long-term Outcomes
Disease
SDC: Oncology