Indirect Treatment Comparisons of Time-to-Event Outcomes with Mis-Matched "Time Zero": Methodology and Application in Resectable Non-Small Cell Lung Cancer

Author(s)

Goring S1, Rogula B1, Lucherini S2, Vo L3, Lozano-Ortega G4, Besada M1, Chaudhary MA3, Varol N2, Lam P3, Girard N5, Spicer J6
1Broadstreet Health Economics & Outcomes Research, Vancouver, BC, Canada, 2Bristol Myers Squibb, Uxbridge, UK, 3Bristol Myers Squibb, Princeton, NJ, USA, 4Broadstreet Health Economics & Outcomes Research, Coquitlam, BC, Canada, 5Institut Curie, Institut Mutualiste Montsouris, Paris, France, 6McGill University Health Center, Montreal, QC, Canada

OBJECTIVES: Immune checkpoint inhibitors have recently been approved for resectable non-small cell lung cancer (rNSCLC): neoadjuvant nivolumab plus chemotherapy (CT) (neoNIVO+CT), and adjuvant atezolizumab (adjATEZO) as treatment following resection and adjuvant CT (adjCT). Head-to-head comparisons are unavailable and differences in "time-zero" across trials preclude traditional indirect treatment comparisons (ITC). Our objective was to develop a method that adjusts for differences in time-zero, to incorporate into an ITC of event-free survival (EFS) between neoNIVO+CT and adjATEZO among patients with stage II-IIIA rNSCLC whose tumours express programmed death ligand-1 (PD-L1) ≥ 50% or PD-L1 ≥ 1%.

METHODS: We designed a time-zero-adjusted ITC by incorporating time-varying and mixture modeling components into a traditional ITC. The evidence network was formed by: CheckMate 816 (neoNIVO+CT vs. neoadjuvant CT [neoCT]), IMpower010 (adjATEZO vs. adjuvant best supportive care; both initiated after adjCT), and NATCH (neoCT vs. adjCT). We set the analysis time-zero to align with CheckMate 816 (in which randomization occurred prior to neoadjuvant treatment) and with NATCH, and estimated time-zero in IMpower010 to occur 7 months later. We used piecewise constant hazard ratios (HRs), partitioned at 7 months. For adjATEZO, we set HR0to7mo vs. adjCT to 1 (no difference), while HR7to36mo was obtained from IMpower010. A mixture model was implemented to address the intent-to-treat principles (i.e., trial dropout/ineligibility for adjATEZO during 0 to 7 months). Bootstrapping was used to estimate 95% confidence intervals (CI), and sensitivity analyses tested modeling assumptions.

RESULTS: Using a common time-zero commencing prior to neoadjuvant treatment or immediate surgery, the EFS HR0to36mo between neoNIVO+CT vs. adjATEZO was 0.29 (95% CI: 0.11, 0.75) for PD-L1 ≥ 50% and 0.45 (0.23, 0.81) for PD-L1 ≥ 1%. Estimates were robust to sensitivity analyses.

CONCLUSIONS: This time-zero-adjusted ITC approach addresses bias arising from differences in time-zero across a network of trials, although additional assumptions should be evaluated through sensitivity analysis.

Conference/Value in Health Info

2023-05, ISPOR 2023, Boston, MA, USA

Value in Health, Volume 26, Issue 6, S2 (June 2023)

Acceptance Code

P15

Topic

Clinical Outcomes, Methodological & Statistical Research, Study Approaches

Topic Subcategory

Comparative Effectiveness or Efficacy, Meta-Analysis & Indirect Comparisons

Disease

no-additional-disease-conditions-specialized-treatment-areas

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