CD4+ lymphocytopenia and Pneumocystis jirovecii pneumonia in a metastatic breast cancer patient treated with palbociclib and corticosteroids

Background: Palbociclib, a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor used to treat metastatic breast cancer, is known to cause myelotoxicity and primarily neutropenia, but its potential to induce severe lymphopenia and opportunistic infections is less understood. Case description: A 61-year...

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Bibliographic Details
Main Authors: Shahar Dekel, Emmanuelle Alaluf, Tal Sella, Avshalom Leibowitz, Ana Belkin
Format: Article
Language:English
Published: SMC MEDIA SRL 2025-07-01
Series:European Journal of Case Reports in Internal Medicine
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Online Access:https://www.ejcrim.com/index.php/EJCRIM/article/view/5519
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Summary:Background: Palbociclib, a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor used to treat metastatic breast cancer, is known to cause myelotoxicity and primarily neutropenia, but its potential to induce severe lymphopenia and opportunistic infections is less understood. Case description: A 61-year-old woman with metastatic breast cancer treated with palbociclib and corticosteroids was admitted with fever and general weakness. Chest radiography and computed tomography showed bilateral consolidation. She was diagnosed with severe cellular immunodeficiency, very low CD4+ T cell count and several opportunistic infections including Pneumocystis jirovecii pneumonia (PCP). Conclusion: This case underscores the need for monitoring lymphocyte counts in patients on CDK4/6 inhibitors, particularly those on concomitant corticosteroid therapy. and considering the risk for opportunistic infections in relevant patients.
ISSN:2284-2594