Immunotherapy in combination with chemotherapy vs. immunotherapy alone for advanced non-small cell lung cancer and programmed death ligand 1 score <50%

Introduction: Little is known about the effectiveness of immunotherapy alone or with chemotherapy for patients with non-small cell lung cancer (NSCLC) and programmed death ligand 1 (PD-L1) expression <50 %. We examined the outcomes of PD-L1 therapy vs. PD-L1 therapy in combination with chemotherapy as first-line treatment among NSCLC patients with PD-L1 score <50 %. Methods: We used administrative claims and prior authorization data of a national insurer from November 2015 to July 2021. We selected patients with Stage IIIb/IV NSCLC and PD-L1 expression <50 %. Each patient was required to have >= 1 claim of a PD-L1 or PD-1 inhibitor. Treatment groups were propensity-score matched 1:1 on baseline characteristics. We measured PD-L1 therapy duration, incident immune-related adverse events (irAEs), healthcare utilization, costs, and overall survival (OS). Results: In the matched sample totaling 176 patients, mean duration of PD-L1 therapy was similar (4.1 [SD 3.3] months combination vs. 4.0 [SD 4.9] months monotherapy, p = 0.800). IrAEs were similar, both for FDArecognized irAEs (48.9 % combination, 48.9 % monotherapy, p = 0.710) and other types (34.1 % combination, 39.8 % monotherapy, p = 0.473). The combination group had more all-cause inpatient stays, ER visits, and outpatient visits (all p < 0.001). Total adjusted all-cause medical cost was $112,833 (95 % CI $5,548-$251,973) higher for combination therapy. We saw no difference in OS (adjusted hazard ratio 1.09 [95 % CI 0.72-1.65]). Conclusion: This study found no difference in adverse drug effects or survival between PD-L1 monotherapy compared to combination therapy for patients with Stage IIIb/IV NSCLC and PD-L1 expression <50 %, though the combination therapy cohort had higher healthcare utilization and costs. MicroAbstract: Use of immunotherapy alone or combined with chemotherapy for patients with non-small cell lung cancer and programmed death ligand 1 expression <50 % is understudied. Our observational study using claims and authorization data from a matched sample of 176 patients found no difference in survival or the rate of adverse drug effects between groups, although the chemo-immunotherapy cohort generated higher overall healthcare costs.