Refractory thrombocytopenia induced by enzalutamide combined with docetaxel chemotherapy in a metastatic castration-resistant prostate cancer patient with bone marrow metastasis: a case report and literature review.

BACKGROUND: Enzalutamide combined with docetaxel is one of the effective therapeutic regimens for metastatic castration-resistant prostate cancer (mCRPC), which significantly prolongs progression-free survival (PFS). For mCRPC patients with bone marrow metastasis (BMM), bone marrow metastasis itself impairs the bone marrow microenvironment and results in reduced hematopoietic function. The combined therapy may induce life-threatening refractory thrombocytopenia, which has been rarely reported in clinical practice. CASE PRESENTATION: A 62-year-old male patient with mCRPC and confirmed bone marrow metastasis was reported herein. After progression to mCRPC, the patient was treated with enzalutamide plus docetaxel, followed by grade 4 refractory thrombocytopenia. The lowest platelet count decreased to 3×109/L, and the patient showed poor response to conventional supportive care. Bone marrow biopsy confirmed progressive infiltration of tumor cells in the bone marrow with occasional megakaryocytes. Docetaxel and enzalutamide were discontinued, and platelet transfusion and subcutaneous injection of recombinant human thrombopoietin were administered. The hemorrhagic manifestations were relieved, while platelet count remained persistently low. CONCLUSION: Enzalutamide combined with docetaxel may increase the risk of refractory grade 4 thrombocytopenia among mCRPC patients with bone marrow infiltration, as illustrated by this single clinical case.