A Retrospective Analysis of Eosinophilia as a Predictive Marker of Response and Toxicity to Cancer Immunotherapy
Tharani Krishnan, Yoko Tomita, Rachel Roberts‐Thomson
Abstract
Aim: To investigate eosinophilia as a potential on-treatment biomarker for patients receiving cancer immunotherapy. Materials & methods: We evaluated the association between eosinophilia and treatment response and toxicity in a retrospective cohort of patients receiving cancer immunotherapy. Results: The study involved 146 patients. Eosinophilia developed in 22%. Patients who developed eosinophilia were more likely to achieve disease control (p = 0.009), with every 0.1 × 109/l rise in eosinophil count, while receiving treatment was associated with a 28% relative increased chance achieving disease control. Although there was a trend toward improved survival, there was no significant association between eosinophilia and improved overall survival (p = 0.136). Patients with eosinophilia were more likely to develop toxicity (p = 0.042). Conclusion: Eosinophilia is a potentially useful biomarker warranting further prospective clinical investigation.Lay abstractImmunotherapy has revolutionized the way we treat many cancers. However, we do not have good predictors for which patients are going to respond to treatment or experience side effects. ‘Eosinophilia’ is when a particular type of white blood cell is present at high levels in the blood. This can occur in patients on immunotherapy. This paper reports a possible link between eosinophilia and the likelihood of responding well to immunotherapy but also the possibility of developing side effects.