A Phase 1 study of abemaciclib plus abiraterone in Japanese patients with metastatic castration-resistant prostate cancer.
Nobuaki Matsubara, Koji Dozono, Karim Nacerddine et al.
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In 30 seconds
This Phase 1, multicentre, open-label study assessed safety, tolerability and pharmacokinetics of abemaciclib 200 mg twice daily with standard-dose abiraterone and prednisolone in Japanese patients with metastatic castration-resistant prostate cancer. Six patients received treatment, and all had at least one treatment-emergent adverse event, mostly low grade; no Grade 4 or 5 events occurred. Pharmacokinetics were consistent with those reported in non-Japanese patients, with no drug–drug interactions detected. The authors concluded that the global recommended Phase 2 dose of abemaciclib was suitable for this population and combination.
Key findings
- All six patients experienced at least one treatment-emergent adverse event; no Grade 4 or 5 events occurred.
- Diarrhoea was the most common adverse event; all cases were Grade 1 except one Grade 2 case.
- Three patients had serious adverse events, resulting in treatment discontinuation in two cases.
- Pharmacokinetics were consistent with non-Japanese patients, and no pharmacokinetic drug–drug interactions were detected.
Why it matters
The findings provide early safety and pharmacokinetic data for combining abemaciclib with abiraterone and prednisolone in Japanese patients with metastatic castration-resistant prostate cancer. The results support use of the global dose in this small study population, while the serious adverse events and treatment discontinuations underscore the need to interpret tolerability findings cautiously.
What to keep in mind
Only six patients were treated, and dose-limiting toxicities were assessed over 28 days, limiting the precision and duration of the safety evidence.