Tumor lysis Syndrome in a Patient with Metastatic Breast Cancer Treated with Alpelisib

Tumor lysis syndrome (TLS) is a rare but life-threatening phenomenon that occurs mainly in patients with aggressive hematologic or highly chemotherapy sensitive solid tumors such as high-grade neuroendocrine carcinoma or testicular cancer. Tumor lysis syndrome is exceedingly rare in hormone receptor-positive, HER2-negative breast cancer. Furthermore, TLS following treatment with alpelisib, a novel phosphatidylinositol 3-kinase (PI3K) inhibitor used to treat PIK3CA-mutated (gene encoding p110α subunit of PI3K), hormone receptor positive advanced breast cancer, has never been described in patients with nonhematologic malignancies.

In the following case, we present a patient with hormone receptor-positive, HER2-negative, PIK3CA-mutated metastatic breast cancer who developed TLS 12 days after starting fulvestrant and alpelisib.

Patient was promptly treated with improvement in her renal function to baseline without requiring renal replacement therapy. Alpelisib was resumed at a reduced dose with no further complications.

Through this case, we discuss the potential complications of TLS and the importance of prompt recognition and treatment.