Correlation analysis between camrelizumab trough concentration levels and efficacy or safety in East Asian patients with advanced lung cancer

Background Camrelizumab combined with chemotherapy is approved across tumor types. However, only a fraction of patients benefits from immunotherapy, and biomarkers such as the expression of PD-L1, tumor mutational burden, and CXCL11 are expensive and suboptimal specificity for cancer patients. An exposure–response (E–R) relationship has been reported in many immune checkpoint inhibitors (ICIs), and the trough concentrations and other drug exposure metrics are broadly used to guide dosing decisions, assess exposure–outcomes relationships, and ultimately predict outcomes based on those relationships. However, the potential use of trough concentration levels for camrelizumab is still not clear. Methods Blood samples were obtained at trough levels after doses 3 and 4 from 77 patients with advanced lung cancer who received camrelizumab (200 mg Q3 W) monotherapy or combined with chemotherapy. We optimized a competitive ELISA method to measure the trough concentration. Results We found that the trough concentration was steady after 3 dose cycles, and the trough concentration level of camrelizumab was higher in patients who developed immune-related adverse effects (irAEs) than in those who did not ( P < 0.05) but was not observed in disease progression and PFS ( P > 0.05). Age (< 65 years old), no smoking history, and efficacy evaluation after 4-dose treatment were associated with PFS ( P < 0.05), but no significance was observed in other clinical characteristics. Total bilirubin and albumin had an influence on trough concentration, and monocytes and albumin were independent risk factors for PFS ( P < 0.05). Conclusions Our results suggest that the trough concentration level of camrelizumab might be a risk factor for the occurrence of irAEs in advanced lung cancer, and using the immunotherapy as early as possible may bring better clinical outcomes.