Eosinophilia in lung cancer patients treated with immunotherapy

Introduction: Eosinophilia has been described as a related adverse effect of immunotherapy (IO) in lung cancer treatment and may be predictive of therapeutic response. Methods: Retrospective review of lung cancer patients under IO seen at Multidisciplinary Department of Thoracic Tumors of our hospital through 2018. Patients were divided in two groups depending on whether or not eosinofilia during IO. Clinically significant eosinophilia was defined by blood eosinophil count > 500/mm3. Results: From a total of 58 patients, 19 (32,8%) experienced eosinophilia during treament. 5 patients had an increase of eosinophil count before the initiation of IO that persisted during treatment. The increase of eosinophil count began, on average, after 3,4 months with a mean peak of 810/mm3. Although median OS has not yet been reached in Kaplan-Meier curves for both groups, mortality at 24 months tended to higher in patients who did not present eosinophilia (30,8% vs 21,1%, p=0,437). Conclusion: Eosinophilia during IO was associated with a better response to treatment in lung cancer patients.