Number needed to treat analysis applied to pembrolizumab plus chemotherapy for first-line treatment of non-squamous non-small cell lung cancer.

Aims: Considering that healthcare systems' financial resources are limited, we aimed to analyze the number needed to treat (NNT) and cost of preventing an event (COPE) related to drug use from Supplementary Health System (SSS) perspective.

Methods: Data from KEYNOTE-189 (NCT02578680) were considered, comparing pembrolizumab + chemotherapy to chemotherapy alone. A cost-per-responder model was developed considering the 24- and 12-month time horizons for overall survival (OS) and progression-free survival (PFS) endpoints, respectively. Restricted mean survival time (RMST) and restricted mean time-on-treatment (ToT) were determined for NNT and COPE calculation. Costs were reported in American dollars (USD) and reflect those related to drug use. The analysis was conducted for the total indicated population, and an exploratory assessment was carried out for subgroups with different programmed death-ligand 1 (PD-L1) expression levels.

Results: Considering PFS data, the overall population NNT to prevent a progression event with pembrolizumab + chemotherapy versus chemotherapy was 2.63 (95%CI: 1.90-4.02) with an estimated COPE of 251,038 USD (95%CI: 181,359-383,717) in the 12-months follow-up. Regarding OS endpoint, overall NNT and COPE were 3.18 (95%CI: 2.20-5.31) and 414,163 (95%CI: 286,528-691,573) USD respectively, in the 24 months follow-up. The PFS NNT was lower with higher levels of PD-L1 expression (1.71, 3.22 and 5.53 for PD-L1 ≥ 50%, PD-L1 1%-49%, and PD-L1 < 1% groups, respectively), while there was no such apparent relationship for OS (3.23, 4.37 and 2.80 for PD-L1 ≥ 50%, PD-L1 1%-49%, and PD-L1 < 1% groups, respectively). The 95%CIs overlapped for PFS and OS NNT across the PD-L1 subgroups.

Conclusion: The magnitude of benefit of the pembrolizumab combination used for first-line non-small cell lung cancer (NSCLC) treatment to improve survival compared to chemotherapy alone was confirmed. The exploratory analysis from the SSS perspective suggests no differences among the PDL-1 subgroups in terms of clinical benefit or economic impact.