Pharmacokinetic/pharmacodynamic drug evaluation of enzalutamide for treating prostate cancer

Enzalutamide-Induced Acute Maculopapular Rash in Treatment of Metastatic Prostate Cancer: First Case Report from a Tertiary Cancer Care Center of North India

Enzalutamide is a new potent inhibitor of the signaling pathway for the androgen receptor with a half-life of 5.8 days. It has been on the market for the treatment of metastatic castration-resistant prostate cancer since November 2013. We report a case of acute generalized exanthematous maculopapular rash induced by enzalutamide. In summary, newer androgen receptor blockers have a propensity to cause skin related adverse effects. Most common among these are apalutamide. Enzalumatamide, per se, is a safe drug and has not been associated frequently in causing maculopapular rash. Few cases has been reported. In all these cases, the drug was discontinued and 2nd line therapy was instituted. In this report, Enzalutamide was withheld for 10 days and anti-histaminics was instituted. After a full recovery, Enzalutamide was reinstituted in treatment. A 62-year-old male patient with no significant medical history, was diagnosed in March 2020 with metastatic prostatic adenocarcinoma. Baseline PSA was 456 ng/ml. PSMA PET scan showed evidence of multiple bony metastasis. He was started on Degarelix subcutaneous injection with oral abiraterone initially. PSA level showed initial decreasing trend till September 2021 followed by sudden increase. Intramuscular Injection leuprolide was started and initial responses were good followed by later rise of PSA from January. Tab Xtandi (Enzalutamide) was added to the regimen from 31.1.22. Three days after starting enzalutamide treatment, the patient experienced an acute skin reaction. It is about of the plaques covered with widespread millimetric non-follicular papules. Enzalutamide was stopped after appearance of rashes to avoid further serious adverse effects. Anti-histaminics were started. Complete resolution of skin lesions occurred within 10 days. Tab Enzalutamide was reinstituted on 11th day after stoppage and on complete resolution of skin resolutions. According to the CTCAE 5.0 criteria, these skin rash was graded as grade 2. In view of evidence in literature and clinical improvement after stoppage, the acute drug reaction was attributed to enzalutamide. Uro oncologist can be confronted with adverse skin drug reactions attributable to new therapeutic molecules. The slow resolution of symptoms seems be due to the long half-life of enzalutamide. It should not be withdrawn from therapy owing to these effects. Rather, it should be with stopped for 10-14 days. Basic treatment with anti-histaminics or topical steroids may be enough to warranty the resolution of symptoms, and the drug (Enzalutamide) can be continued thereafter.

Newly identified adverse events of enzalutamide using the food and drug administration adverse event reporting system

OBJECTIVES

Enzalutamide, a second-generation anti-androgen drug, is an androgen receptor inhibitor developed to overcome resistance to first-generation anti-androgens, such as bicalutamide. This study aimed to identify previously undisclosed adverse events associated with enzalutamide.

METHODS

Adverse reactions following enzalutamide administration were extracted from the Food and Drug Administration Adverse Event Reporting System (FAERS) database, and the data obtained were from 2014 to 2023. Four algorithms, namely ROR, PRR, BCPNN, and EBGM, were used to detect signs of adverse reactions associated with enzalutamide use.

RESULTS

This study determined several adverse reactions in the nervous system, including hypogeusia, ageusia, dysgeusia, normal-pressure hydrocephalus, dementia, amnesia, balance disorders, and seizure-like phenomena. The mental aspects manifested as laziness, confusion, and eating disorders. Gastrointestinal system-related adverse reactions included dysphagia, constipation, fecal hardening, and abdominal discomfort. We identified several previously unreported adverse reactions, including normal-pressure hydrocephalus, dementia, balance disorders, eating disorders, and dysphagia.

CONCLUSION

Our study revealed novel adverse events associated with enzalutamide, particularly in the nervous system, that have not been previously documented. These findings have important implications for future clinical medication guidelines.

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.

Pharmacokinetics of Darolutamide in Mouse - Assessment of the Disposition of the Diastereomers, Key Active Metabolite and Interconversion Phenomenon: Implications to Cancer Patients

BACKGROUND

Darolutamide is recently approved for the treatment of non-metastatic castrate resistance prostate cancer. Hitherto, no stereoselective pharmacokinetic data have been published pertaining to darolutamide and its diastereomers in animals or humans. The key aims of the experiment were to examine darolutamide, S,S-darolutamide and S,R-darolutamide with respect to (a) assessment of in vitro metabolic stability and protein binding and (b) characterization of in vivo oral and intravenous pharmacokinetics in mice.

METHODS

In vitro (liver microsomes stability and protein binding) and in vivo experiments (oral/intravenous dosing to mice) were carried out using darolutamide, S,S-darolutamide and S,Rdarolutamide. Besides, tissue levels of darolutamide, S,S-darolutamide and S,R-darolutamide were measured following oral and intravenous dosing. Appropriate plasma/tissue samples served to determine the pharmacokinetics of various analytes in mice. Liquid chromatography in tandem with mass spectrometry procedures enabled the delineation of the plasma pharmacokinetics, in vitro and tissue uptake data of the various analytes.

RESULTS

Chiral inversion was absent in the metabolic stability study. However, darolutamide showed profound stereoselectivity (S,S-darolutamide greater than S,R-darolutamide) after either intravenous or oral dosing. S,R-darolutamide but not S,S-darolutamide showed conversion to its antipode post oral and intravenous dosing to mice. Regardless of oral or intravenous dosing, active keto darolutamide formation was evident after administration of darolutamide, S,S-darolutamide or S,R- darolutamide. Tissue data supported the observations in plasma; however, tissue exposure of darolutamide, S,Sdarolutamide and S,R-darolutamide was much lower as compared to plasma.

CONCLUSION

In lieu of the human pharmacokinetic data, although the administration of diastereomeric darolutamide was justified, it is proposed to delineate the clinical pharmacokinetics of S,Rdarolutamide and S,S-darolutamide relative to darolutamide in future clinical pharmacology studies.

Emerging Challenges to the Safe and Effective Use of Methadone for Cancer-Related Pain in Paediatric and Adult Patient Populations

Methadone continues to be an important medication for the treatment of paediatric and adult cancer-related pain. Appropriate patient selection to ensure safe and effective treatment by a team of clinicians who appreciate and are familiar with methadone and its unique pharmacology is crucial. Unlike morphine and other more common opioids, methadone is purported to have involvement with delta-opioid receptor and higher affinity as an N-methyl-D-aspartate-receptor antagonist. Clinically this gives it the advantage of being effective for both nociceptive and neuropathic pain, but also may be useful in the setting of tolerance to other opioids. Methadone also comes in multiple available formulations that can be administrated through a variety of routes beyond the oral route. Challenges with methadone in treating cancer-related pain include drug interactions specifically as it relates to new targeted cancer therapies. Recent guidelines recommend electrocardiogram monitoring with methadone and there is potential for additive cardiac toxicity in the oncology setting. Appropriate dosing of methadone for pain management given age, organ dysfunction, and patients who are on methadone maintenance therapy are also key factors. This article aims to provide clinicians with evidence and clinical practice guidelines for safe and appropriate use of methadone including indication, initiation, and monitoring given its complexity for management of pain in the dynamic oncology setting.