abiraterone-acetate and Long-QT-Syndrome

Abiraterone is the active metabolite of the pro-drug abiraterone acetate (AA) and a selective inhibitor of CYP17, a key enzyme in testosterone synthesis, and improves overall survival in postdocetaxel metastatic castration-resistant prostate cancer (mCRPC). This open-label, single-arm phase 1b study was conducted to assess the effect of AA and abiraterone on the QT interval.. The study was conducted in 33 patients with mCRPC. Patients received AA 1,000 mg orally once daily + prednisone 5 mg orally twice daily. Electrocardiograms (ECGs) were collected in triplicate using 12-lead Holter monitoring. Baseline ECGs were obtained on Cycle 1 Day-1. Serial ECG recordings and time-matched pharmacokinetic (PK) blood samples were collected over 24 h on Cycle 1 Day 1 and Cycle 2 Day 1. Serial PK blood samples were also collected over 24 h on Cycle 1 Day 8.. After AA administration, the upper bound of the 2-sided 90 % confidence interval (CI) for the mean baseline-adjusted QTcF change was <10 ms; no patients discontinued due to QTc prolongation or adverse events. No apparent relationship between change in QTcF and abiraterone plasma concentrations was observed [estimated slope (90 % CI): 0.0031 (-0.0040, 0.0102)].. There is no significant effect of AA plus prednisone on the QT/QTc interval in patients with mCRPC.

Topics: Abiraterone Acetate; Androgens; Androstadienes; Antineoplastic Combined Chemotherapy Protocols; Drug Administration Schedule; Electrocardiography; Heart Rate; Humans; Long QT Syndrome; Male; Neoplasms, Hormone-Dependent; Orchiectomy; Prednisone; Prostatic Neoplasms; Steroid 17-alpha-Hydroxylase

Abiraterone is a medication frequently used for metastatic castrate-resistant prostate cancer. We report a case of non-sustained episodes of TdP associated with severe hypokalemia due to androgen-deprivation therapy. Few case presentations describe this association; the novelty lies in the potentially lethal cardiovascular events among cancer patients receiving hormonal therapy.. A 70-year-old male presented with recurrent syncope without prodrome. ECG revealed frequent ventricular ectopy, non-sustained episodes of TdP, and severe hypomagnesemia and hypokalemia. During potassium and magnesium infusion for repletion, the patient underwent temporary transvenous atrial pacing. As part of the work-up, coronary angiography revealed a mild coronary artery disease, and transthoracic echocardiogram showed a moderately depressed ejection fraction. After electrolyte disturbances were corrected, the QT interval normalized, and transvenous pacing was no longer necessary. Abiraterone was discontinued during the admission, and the patient returned to baseline.. Cancer treatment is complex and requires a multidisciplinary approach. We presented a case of non-sustained TdP associated with androgen-deprivation therapy in an elderly patient with mild coronary artery disease and moderately reduced ejection fraction. Close follow-up and increased awareness are required in patients with hormonal treatment, especially in the setting of other cardiovascular risk factors.

Topics: Abiraterone Acetate; Aged; Antineoplastic Agents; Cardiac Pacing, Artificial; Fluid Therapy; Heart Rate; Humans; Long QT Syndrome; Male; Prostatic Neoplasms, Castration-Resistant; Steroid Synthesis Inhibitors; Syncope; Torsades de Pointes; Treatment Outcome

Topics: Abiraterone Acetate; Electrocardiography; Humans; Long QT Syndrome; Torsades de Pointes