Cost-effectiveness analysis of pembrolizumab as an adjuvant treatment of early-stage non-small cell lung cancer following complete resection and platinum-based chemotherapy in Canada.

Aim: To assess the cost-effectiveness of adjuvant pembrolizumab (Keytruda) versus routine observation of adult patients with stage IB (T2a ≥ 4 cm) -IIIA with programmed cell death ligand 1 (PD-L1) tumor proportion score (TPS) <50% who have undergone complete resection and platinum-based chemotherapy from the Canadian public healthcare payer perspective.

Materials and methods: A Markov model was constructed to capture clinical and economic outcomes across four health states: disease-free (DF), local-regional recurrence (LR), distant metastases (DM), and death. Transition probabilities (TPs) from the DF state were populated using clinical trial data from KEYNOTE-091. TPs from the LR state were from real-world evidence (RWE). Clinical trial and network meta-analysis output populated transitions from DM. TPs from LR and DM were calibrated to fit the KEYNOTE-091 survival data. Costs were reported in 2023 Canadian dollars and utilities were based on data from KEYNOTE-091 and metastatic NSCLC clinical trials.

Results: Pembrolizumab extended life years (LYs) (1.55) and quality-adjusted life years (QALYs) (1.19). Costs increased by $84,050, resulting in an incremental cost-effectiveness ratio (ICER) per additional LY of $54,219 and per additional QALY of $70,725, below the willingness-to-pay threshold of $100,000. Survival gains associated with pembrolizumab were attributed to more time spent in the DF health state. Higher costs for pembrolizumab were due to adjuvant treatment costs but were partially offset by lower subsequent treatment costs in downstream health states, reflecting a lower risk of recurrence associated with pembrolizumab. The model results remained robust across scenario and sensitivity analyses.

Limitations: Due to lack of transition probabilities starting from the LR and DM states from the KEYNOTE-091 trial, TPs from the LR and DM states were estimated using non-trial sources.

Conclusions: Adjuvant pembrolizumab was found to be cost-effective compared to routine observation from the public healthcare payer perspective in Canada.