4CPS-014 Safety profile of enzalutamide in patients with castration-resistant prostate cancer: real-life data

<h3>Background and Importance</h3> Enzalutamide’s real-world safety in mCRPC requires validation to identify and manage adverse reactions effectively. <h3>Aim and Objectives</h3> To describe the safety profile of enzalutamide in metastatic castration-resistant prostate cancer (mCRPC) patients. <h3>Material and Methods</h3> This retrospective study included mCRPC patients treated with enzalutamide from January 2015 to December 2023. Data were collected from the Hospital Pharmacy programme’s outpatient module and electronic medical record, including: age, ECOG status, PSA at the start of treatment, Gleason score, metastasis location, treatment line, and reason for discontinuation. Adverse reactions (ARs) and toxicity grades were classified by CTCAE v5 and grouped by system according to MedDRA. Descriptive statistics were used for analysis. <h3>Results</h3> Twenty-nine men received enzalutamide (240 mg/day), median age 76.9 years (IQR 67.5–84.9); 82.8% had ECOG 0–1, 13.8% ECOG ≥2. Median PSA was 32.7 ng/mL (IQR 7.1–90.6). Gleason scores were ≤6 in 10.3%, 7 in 17.2%, ≥8 in 65.6%. Metastasis locations were lymph nodes in 55.2%, bones in 37.9%, and bones+visceral in 6.9%. Enzalutamide was first-line in 20.7%, second-line in 55.2%, and third/fourth-line in 24.1%. Treatment was discontinued in 23 (79.3%) patients, with 16 (69.6%) due to progression, 5 (21.7%) due to toxicity, and 2 (8.7%) due to general health deterioration unrelated to enzalutamide. Toxicity-related discontinuations included persistent Grade II nausea, Grade III seizures, Grade III hypersensitivity reactions, Grade IV asthenia, and Grade III focal seizures. Patients experiencing neurological ARs had no prior neurological history. No patients reduced their dose due to toxicity. Twenty-five (86.2%) patients experienced ARs, with 36 ARs recorded: 83.3% were Grade I-II and 16.7% Grade III-IV. Grade I-II ARs included: 3 haematologic and lymphatic system disorders (anaemia), 2 nervous system disorders(headache, behavioural changes), 4 vascular disorders (hot flashes), 2 ocular disorders (visual acuity loss), 6 gastrointestinal disorders (nausea, constipation, anorexia, diarrhoea), 2 renal and urinary disorders (fluid retention), 2 respiratory disorders (dyspnoea), 4 skin disorders (cutaneous reactions), 2 musculoskeletal disorders (tremor, muscle pain), and 9 general disorders (asthenia) Grade III-IV ARs included: 2 cases of asthenia,1 fluid retention,1 hypersensitivity reaction,1 anorexia,1 tremor,1 seizure,1 hypertension, and 1 focal seizures. <h3>Conclusion and Relevance</h3> Enzalutamide was generally well tolerated, with most ARs being Grade I-II. Toxicity-related discontinuation was higher than in clinical trials but lower than in some real-world studies. Visual acuity loss and tremor, not listed in the official drug label. Both events have been reported to FEDRA and Eudra Vigilance pharmacovigilance systems. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest