Abstract / Summary
Background: Combination therapy comprising immune checkpoint inhibitors (ICIs) and chemotherapy is standard treatment for many cancer types. However, the management of adverse events (AEs) induced by combination therapy is more complicated than that of AEs induced by ICI monotherapy. Although immune-related AEs (irAEs) induced by ICIs and AEs induced by chemotherapy require distinct therapeutic approaches, distinguishing between them can be challenging. Therefore, in this exploratory study, we aimed to investigate whether lymphocyte proportion could serve as a candidate biomarker associated with the occurrence of irAEs in patients receiving ICI plus chemotherapy combination therapy.
Patients and methods: We categorized 122 patients into the irAE group (those who experienced irAEs), chemo-AE group (those with chemotherapy-induced AEs), and non-AE group (those without AEs) and analyzed their lymphocyte proportions before one course (baseline sample) and two courses (two-course sample) of treatment.
Results: Lymphocyte proportions of the baseline samples did not differ between the non-AE, chemo-AE, and irAE groups. The lymphocyte proportion of the two-course sample of the irAE group was significantly higher than that of the non-AE group (25.8% vs. 21.9%; p < 0.05). The lymphocyte proportion of the two-course sample of the irAE group was significantly higher than that of the chemo-AE group (25.8% vs. 19.6%; p < 0.05). The multivariate logistic regression analysis showed that a lymphocyte proportion ≥ 23.9% in the two-course sample significantly increased the risk of irAEs (odds ratio = 3.04; p < 0.05).
Conclusions: An increased lymphocyte proportion before the two courses of treatment was associated with the occurrence of irAEs and may serve as a candidate biomarker.