Persistent racial/ethnic associated disparity in anti-tumor effectiveness of immune checkpoint inhibitors despite equal access.

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of both lung cancer and head and neck squamous cell carcinoma demonstrating clear benefit over traditional chemotherapy alone in the metastatic setting. While the overwhelming majority of ICI trial participants have been White patients, results of these trials have been broadly applied to patients of all ethnic/racial backgrounds. It has, therefore, not been well defined if response to ICIs differs between ethnic/racial populations or socio-economic groups. We reviewed response to ICI of 208 patients with diagnoses of lung or head and neck cancers treated with ICI between 2015 and 2020 at one of three clinical pavilions associated with the Dan L. Duncan Comprehensive Cancer Center at Baylor College of Medicine in Houston, TX. Two of these pavilions (Harris Health System and the Michael E. DeBakey Veterans Affairs Medical Center) serve large minority patient populations and provide equal access of care to patients regardless of means. Of the 208 patients, 175 had a diagnosis of lung cancer [non-small cell lung carcinoma (NSCLC) or small cell lung cancer (SCLC)] and 33 had a diagnosis of head and neck squamous cell carcinoma (HNSCC); 38% self-identified as Black, 45% as non-Hispanic White, and 18% as Hispanic. The objective response rate (ORR) was similar for lung cancer (31.4%) and HNSCC patients (27.3%) (p=0.894). Statistically, the ORR for Hispanic and Black patients did not differ compared to non-Hispanic White patients (H 23.7%, B 28.6%, W 35.5%; H vs. W p=0.189; B vs. W p=0.338). When considering patients treated with ICI monotherapy, the ORR for Hispanic patients dropped to 13.3% and was significantly lower than the ORR of the non-Hispanic White patients while the ORR of Black and non-Hispanic White patients remained about the same (B 29.3% and W 34.6%, H vs. W p=0.0285; B vs. W p=0.5131). Immune related adverse events (irAEs) were the lowest in the Hispanic population occurring in only 30% of patients compared to 50% of patients exhibiting irAEs in the Black and non-Hispanic white cohorts. ICIs demonstrate comparable anti-tumor effects in lung cancer (NSCLC + SCLC) and HNSCC during routine clinical practice regardless of race or ethnicity. The significantly lower ORR observed in our cohort for Hispanic patients, particularly when used as monotherapy, is an unexpected finding and will require additional study to identify potential biological and non-biological confounders which could contribute to reduced ICI effectiveness in this patient population.