Acute Lymphoblastic Leukemia in a Patient With Advanced Breast Cancer Treated With Cyclin-Dependent Kinase 4/6 Inhibitors and Endocrine Therapy

This case shares the case of a post-menopausal woman who develops Philadelphia chromosome-positive B cell acute lymphoblastic leukemia (B-ALL) while receiving treatment for invasive ductal carcinoma (IDC) of the breast. The patient received a cyclin-dependent kinase (CDK) 4/6 inhibitor + aromatase inhibitor (AI) for the IDC; hyperfractionate cyclophosphamide, vincristine sulfate, doxorubicin hydrochloride (Adriamycin), methotrexate, and cytarabine (hyperCVAD), and the steroid hormone dexamethasone were added to treat the B-ALL. HyperCVAD combined with CDK 4/6 inhibitor + AI was very well tolerated. The CDK 4/6 inhibitor and AI were only held once in the treatment course due to adverse effect (AE) intolerance. The patient remains on a CDK 4/6 inhibitor and ponatinib with only low-grade fatigue as an AE. This case underscores the importance of a concurrent approach to managing hematologic and breast malignancies. The combined treatment regimens were effective and well-tolerated. Vigilant follow-up is essential for patients in remission from both malignancies, ensuring effective disease surveillance and treatment management. Integrated care remains pivotal for optimal outcomes.