ESMO Asia Congress 2022

Abstract 170P

Background

1.4 million new prostate cancer cases were detected in 2020. Survival has improved in metastatic castration-resistant prostate cancer (mCRPC) because of the development of effective drugs such as abiraterone acetate, but universal accessibility to treatment is not always possible because of cost constraints in lower- and middle-income countries. Abiraterone in fasting state is the standard of care in mCRPC. Despite a large food effect, it was administered under fasting conditions in its pivotal trials. Recently, the National Comprehensive Cancer Network (NCCN) has included low-dose abiraterone (250 mg/day) with food as an alternative treatment option to full-dose abiraterone (1,000 mg/day) fasting. This translates to 75% cost reduction.

Methods

In this cohort study mCRPC Patients with progression were offered low dose abiraterone with low fat meal along with prednisone 5 mg twice daily. Prostate-specific antigen (PSA) was assessed monthly and toxicity assessment was made every week. Final PSA response (≥ 50% reduction) and toxicity assessment were done at 12 weeks. In case of grade IV toxicity (Anemia, Hypertension, Hypokalemia, hypocalcemia – CTC AE V5.0) because of higher drug bioavailability, patient would be offered full dose abiraterone. 20 patients were offered low dose abiraterone in 2020.

Results

12 out of 20 (60%) patients achieved desired PSA response at 12 weeks which is a bit on higher side compared to standard dose abiraterone (recent literature). Fortunately, none of the patient developed grade IV toxicity. This finding was assuring, and no patient shifted to standard dosing.

Conclusions

Low dose abiraterone (with low-fat breakfast) is noninferior to full dose abiraterone with respect to PSA metrics. Toxicity is the major thing to look at and given the pharmacoeconomic implications it’s imperative to adopt this strategy in places where affordability is the issue. Let the patients have something rather than nothing!