OBJECTIVES: Results from the KEYNOTE-189 trial demonstrated that first-line pembrolizumab plus pemetrexed-platinum significantly improved overall survival (OS) and progression-free survival (PFS) compared with pemetrexed-platinum alone in patients with metastatic non-squamous non‒small-cell lung cancer (NSCLC), irrespective of tumor programmed death-ligand 1 (PD-L1) expression. To support health systems sustainability decisions in Colombia, we calculated the number needed to treat (NNT) and cost of preventing an event (COPE) using PFS and OS data from the KEYNOTE-189 protocol-specified final analysis and Colombian costs.

METHODS: A cost-per-responder model was developed considering a 24-month time horizon for OS & PFS. NNT based on Restricted mean survival time (RMST) and COPE were calculated for the ITT population and PD-L1 TPS≥50%, PD-L1 TPS=1-49%, and PD-L1 TPS<1% subgroups. Modelled costs reflected Colombian drug acquisition costs reported in local currency and converted to American dollars (USD).

RESULTS: Over a 24-months period, 3.13 patients (NNT RMST OS = 3.13 - 95% CI 2.18, 5.17) needed to be treated with pembrolizumab combination to prevent an additional death in comparison with chemotherapy and 1.48 patients (NNT RMST PFS = 1.48 - 95% CI 1.08, 2.17) needed to be treated to prevent an additional disease progression or death. COPE to prevent death or progression in the ITT population was USD 110,628 (95% CI: 80,729–162,205) and USD 233,964 (95% CI: 162,952–386,452) for PFS and OS, respectively. Across PD-L1 subgroups, NNT ranged from 1.02-2.49 for PFS and 2.74-4.23 for OS, with COPE ranging from USD 76,244-316,188

CONCLUSIONS: The low observed NNT RMST in the ITT population and across PDL-1 subgroups highlights the clinical effectiveness of pembrolizumab combination for patients with NSCLC regardless of PD-L1 expression level. The COPE in the ITT population and among PD-L1 level subgroups, indicates a manageable per-patient financial impact in Colombia