Enzalutamide-induced severe thrombocytopenia complicated by a seizure in a 76-year-old man with castration-resistant prostate cancer

A case of castration-resistant metastatic prostate cancer who continued treatment with enzalutamide after epileptic seizure

INTRODUCTION

Enzalutamide is an androgen receptor inhibitor and is used in metastatic castration-resistant prostate cancer. Seizure is a rare side effect of enzalutamide. In this case, the patient had an epileptic seizure while on enzalutamide treatment. His treatment management and and use of enzalutamide afterwards is discussed.

CASE REPORT

A 78-year-old male patient who received previous treatments for metastatic castration-resistant prostate cancer was started on enzalutamide due to progression, and had an epileptic seizure while taking enzalutamide was presented. Different pathologies such as the use of other drugs, brain metastasis, bleeding, electrolyte, liver and kidney disorders that can cause epileptic seizures were explored and not found to be the cause in this patient. No neurological pathology was found in the patient after the seizure.

MANAGEMENT AND OUTCOME

Enzalutamide and antiepileptic treatment were initiated simultaneously again in the patient whose treatment was interrupted after the seizure and no pathology was found in the brain magnetic resonance imaging. Under this dual treatment, the patient did not have seizures again.

DISCUSSION

Although observed rarely, enzalutamide-induced epileptic seizure is a known side effect. However, a review of literature did not reveal any report on patients for whom enzalutamide and antiepileptic treatment were initiated and followed up simultaneously after seizures. This case report will contribute to the literature for patients whose treatment options have been exhausted and who may benefit significantly from continued use of enzalutamide despite having a seizure.

Stevens-Johnson Syndrome Caused by Enzalutamide: A Case Report and Literature Review

OBJECTIVE

Enzalutamide is the most frequently prescribed compound for treating metastatic castration-resistant prostate cancer (mCRPC). Common adverse drug events of enzalutamide are febrile neutropenia, hot flashes, hypertension, and fatigue.

METHODS

We present a case of a patient with mCRPC who received enzalutamide and developed Stevens-Johnson syndrome (SJS). The culprit drug was confirmed using the Naranjo Adverse Drug Reaction Probability Scale. Clinical characteristics and management principles were analyzed in combination with literature reports.

RESULTS

SJS occurred within two weeks of enzalutamide therapy. Supportive care such as steroid treatment led to a complete resolution of skin lesions and improved clinical symptoms after three weeks.

CONCLUSION

Most cutaneous adverse events occur early during enzalutamide therapy, and close observation should be given within two weeks of starting treatment.

[Adverse drug reactions profiles for abiraterone and enzalutamide: A pharmacovigilance descriptive analysis]

OBJECTIVE

The aim of this study was to describe the profile of adverse drug reactions (ADRs) observed with abiraterone and enzalutamide, based on cases registered in the French regional pharmacovigilance centres to identify potential pharmacovigilance signals.

METHODS

We extracted from the French pharmacovigilance database all cases of ADRs or drug interactions involving abiraterone or enzalutamide from the time they market authorization date until December 31st, 2017. Signal detection results have been transmitted by the French Agency for Health Products (ANSM). The data were compared with those of the risk management plans for each drug and the literature.

RESULTS

Among the 233 observations analyzed, nearly 62% involved abiraterone as a suspect drug and 38% involved enzalutamide; only 1 case involved both drugs. The ADRs profile is different between the drugs. Abiraterone is mostly associated with expected cardiac diseases (heart failure, and QT prolongation), expected with the drug. Also described, several cases of hepatotoxicity have been reported, however some cases with fatal outcome suggest that despite a follow-up of the liver function tests, it is difficult to anticipate this risk. Signals concerning acute renal failure and ischemic stroke have arisen. Enzalutamide is more particularly associated with various neurological disorders (convulsions, hallucinations, fatigue, and memory impairment) expected with the drug. While ischemic heart disease is also expected, signals of heart failure and atrial fibrillation have arisen. A potential hepatotoxicity of the molecule is discussed because of cases of cholestatic hepatitis.

CONCLUSION

The analysis of the French pharmacovigilance database cases allows to confirm an expected and monitored risk profile in the risk management plan for both drugs. Several signals have arisen, some of which will be investigated through a pharmacoepidemiology study.