Pneumotoxicidade associada ao uso de pembrolizumabe em paciente com câncer de mama – evolução clínica compatível com pneumonia em organização: relato de caso

Abstract

Introduction: pembrolizumab, an immune checkpoint inhibitor, has broadened therapeutic options in neoplasms, including breast cancer. However, its use may be associated with adverse pulmonary events, such as pneumonitis. We report a case with clinical and radiological evolution compatible with organizing pneumonia, highlighting the importance of early suspicion and management. Case report: a 55-year-old female patient, diagnosed with triple-negative breast cancer (T2N1M0), began treatment with neoadjuvant chemotherapy (dense dose-acting T-cell - Paclitaxel), followed by surgery and radiotherapy. In January 2024, she started immunotherapy with pembrolizumab. From November onwards, she developed progressive dyspnea and a dry cough. Chest tomography revealed bilateral ground glass opacities and consolidations, with a pattern compatible with organizing pneumonia, leading to the suspension of immunotherapy. There was no improvement with antibiotics and corticosteroids for 10 days. The diagnostic hypothesis was pneumonitis due to hypersensitivity to pembrolizumab. Infectious causes were ruled out. In a multidisciplinary session, it was decided to suspend immunotherapy and initiate corticosteroids at an immunosuppressive dose for four weeks, with progressive tapering. Following respiratory physiotherapy, the patient showed significant clinical improvement, with a change to mild dyspnea (mMRC 3 to 0), resulting in a good therapeutic response. Discussion: immunotherapy with immune checkpoint inhibitors, such as pembrolizumab, represents a significant advance in the treatment of triple-negative breast cancer, especially in advanced stages. However, its use may be associated with immune-mediated adverse events, among which pneumonitis stands out as one of the main pulmonary manifestations. In this case, the patient began to present progressive respiratory symptoms after several cycles of immunotherapy, with tomography showing findings compatible with organizing pneumonia, an inflammatory pattern frequently associated with pulmonary toxicity from these agents. The lack of response to antimicrobials and the exclusion of infectious causes contributed to the suspicion of immune-mediated pneumonitis. The favorable evolution with the use of systemic corticosteroids reinforced this diagnosis. Conclusion: this case illustrates the importance of continuous surveillance for the early identification of pulmonary toxicities associated with immunotherapy, as well as the need for a multidisciplinary approach in therapeutic management, including the definitive discontinuation of the immunotherapy and the timely initiation of corticosteroid therapy.