Comparative Study of Abiraterone Acetate Tablets (I) or ZYTIGA® in Patients With Metastatic Castration-resistant Prostate Cancer

A Randomized, Open-Label, Multi-Center, Parallel Controlled Study Comparing the Serum Testosterone Levels in Patients With Metastatic Castration-Resistant Prostate Cancer After Oral Administration of Abiraterone Acetate Tablets (I) or ZYTIGA®

To evaluate whether the efficacy of the abiraterone acetate tablets (I) is comparable to that of the ZYTIGA®) by comparing the serum testosterone concentrations on Day 9 and/or Day 10 after oral administration of the two formulations in patients with metastatic castration-resistant prostate cancer (mCRPC).

Inclusion Criteria:

1. Males, ≥ 18 years old;
2. Histologically or cytologically diagnosed with prostate adenocarcinoma, without neuroendocrine or small cell characteristics, and having metastatic lesions with imaging evidence (such as positive bone scan or metastatic lesions on CT/MRI);
3. Serum testosterone level < 50 ng/dL or 1.7 nmol/L at the screening; subjects who have not undergone bilateral orchidectomy must plan to continue medication throughout the study to maintain therapy with effective GnRH agonist or antagonist;
4. Progression of prostate cancer as confirmed by diagnostic files, meeting one of the conditions for disease progression: 1) Biochemistry evidence of recurrence: continuous 3 rises of PSA (taken a minimum of 1 week apart) from a baseline measurement of at least 2 ng/mL, greater than 50% of the minimum value in 2 rises; 2) Radiographic progression: a clear evidence of new lesion; 2 or more new bone lesions appearing on bone scan; CT or MRI showing lesion progression (RECIST 1.1);
5. ECOG performance status score of ≤ 1;
6. Life expectancy of ≥ 6 months;
7. Major organs are functioning well

Exclusion Criteria:

1. History of pituitary or adrenal dysfunction;
2. Have used flutamide within 4 weeks before the first dose of study treatment, and bicalutamide or nilutamide within 6 weeks before the first dose of study treatment;
3. Prior therapy with CYP17 inhibitors (such as abiraterone acetate, ketoconazole, TAK-700, etc.) or investigational drugs or marketed drugs of new androgen receptor antagonists (such as enzalutamide, apalutamide, SHR3680, ODM-201, and proxalutamide);
4. Have received 5-reductase inhibitors (such as finasteride and dutasteride), estrogen, progesterone, any herbal products (such as saw palmetto) that may decrease PSA levels, and radiotherapy within 4 weeks prior to the start of study medication;
5. Have previously received biotherapy or cytotoxic chemotherapy for mCRPC; patients who have completed docetaxel treatment for at least 1 year before enrollment can participate in screening;
6. Prostate cancer with moderate to severe pain symptoms, with a score of > 3 for Question 3 (the worst pain in the last 24 hours, 0-1 point means asymptomatic, 2-3 points mean mild symptoms) of the Brief Pain Inventory-Short Form (BPI-SF);
7. With contraindications to the use of glucocorticoids, such as uncontrolled persistent infections or other conditions;
8. Chronic diseases that require systemic corticosteroid therapy (> 10 mg/day prednisone or equivalent). Patients who have discontinued the administration or reduced the dose to < 10 mg within 14 days prior to the start of study treatment are eligible;
9. Presence of abdominal fistula, gastrointestinal perforation, abdominal abscess, or other abnormal gastrointestinal function within 6 months before the first dose of study treatment, which may affect drug absorption as judged by the investigator;
10. Presence of active heart disease within 6 months prior to the first dose of study treatment, including: severe/unstable angina, myocardial infarction, symptomatic congestive heart failure, left ventricular ejection fraction < 50%, and severe arrhythmia requiring treatment or New York Heart Association (NYHA) Class III-IV heart failure;
11. Inability to swallow the whole tablet;
12. Other conditions that make the patient unsuitable for the study as judged by the investigator.