FDA Label for Abiraterone
View Indications, Usage & Precautions
- 1 INDICATIONS AND USAGE
- 2 DOSAGE AND ADMINISTRATION
- 2.1 RECOMMENDED DOSE FOR METASTATIC CRPC
- 2.3 IMPORTANT ADMINISTRATION INSTRUCTIONS
- 2.4 DOSE MODIFICATION GUIDELINES IN HEPATIC IMPAIRMENT AND HEPATOTOXICITY
- 2.5 DOSE MODIFICATION GUIDELINES FOR STRONG CYP3A4 INDUCERS
- 3 DOSAGE FORMS AND STRENGTHS
- 4 CONTRAINDICATIONS
- 5.1 HYPERTENSION, HYPOKALEMIA AND FLUID RETENTION DUE TO MINERALOCORTICOID EXCESS
- 5.2 ADRENOCORTICAL INSUFFICIENCY
- 5.3 HEPATOTOXICITY
- 6 ADVERSE REACTIONS
- 6.1 CLINICAL TRIAL EXPERIENCE
- 6.2 POSTMARKETING EXPERIENCE
- 7.1 DRUGS THAT INHIBIT OR INDUCE CYP3A4 ENZYMES
- 7.2 EFFECTS OF ABIRATERONE ON DRUG METABOLIZING ENZYMES
- 8 USE IN SPECIFIC POPULATIONS
- 8.1 PREGNANCY
- 8.2 LACTATION
- 8.3 FEMALES AND MALES OF REPRODUCTIVE POTENTIAL
- 8.4 PEDIATRIC USE
- 8.5 GERIATRIC USE
- 8.6 PATIENTS WITH HEPATIC IMPAIRMENT
- 8.7 PATIENTS WITH RENAL IMPAIRMENT
- 10 OVERDOSAGE
- 11 DESCRIPTION
- 12.1 MECHANISM OF ACTION
- 12.3 PHARMACOKINETICS
- 12.6 QT PROLONGATION
- 13.1 CARCINOGENESIS, MUTAGENESIS, AND IMPAIRMENT OF FERTILITY
- 13.2 ANIMAL TOXICOLOGY AND/OR PHARMACOLOGY
- 14 CLINICAL STUDIES
- 16 HOW SUPPLIED/STORAGE AND HANDLING
- 17 PATIENT COUNSELING INFORMATION
Abiraterone Product Label
The following document was submitted to the FDA by the labeler of this product Hikma Pharmaceuticals Usa Inc.. The document includes published materials associated whith this product with the essential scientific information about this product as well as other prescribing information. Product labels may durg indications and usage, generic names, contraindications, active ingredients, strength dosage, routes of administration, appearance, warnings, inactive ingredients, etc.
1 Indications And Usage
Abiraterone acetate tablets are indicated in combination with prednisone for the treatment of patients with
• Metastatic castration-resistant prostate cancer (CRPC)
2 Dosage And Administration
2.1 Recommended Dose For Metastatic Crpc
The recommended dose of Abiraterone Acetate Tablets is 1,000 mg (two 500 mg tablets or four 250 mg tablets) orally once daily with prednisone 5 mg orally twice daily.
2.3 Important Administration Instructions
Patients receiving abiraterone acetate tablets should also receive a gonadotropin-releasing hormone (GnRH) analog concurrently or should have had bilateral orchiectomy. Abiraterone acetate tablets must be taken on an empty stomach, either one hour before or two hours after a meal [see Clinical Pharmacology (12.3)]. The tablets should be swallowed whole with water. Do not crush or chew tablets.
2.4 Dose Modification Guidelines In Hepatic Impairment And Hepatotoxicity
Hepatic Impairment
In patients with baseline moderate hepatic impairment (Child-Pugh Class B), reduce the recommended dose of abiraterone acetate tablets to 250 mg once daily. In patients with moderate hepatic impairment monitor ALT, AST, and bilirubin prior to the start of treatment, every week for the first month, every two weeks for the following two months of treatment and monthly thereafter. If elevations in ALT and/or AST greater than 5X upper limit of normal (ULN) or total bilirubin greater than 3X ULN occur in patients with baseline moderate hepatic impairment, discontinue abiraterone acetate tablets and do not re-treat patients with abiraterone acetate tablets [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)].
Do not use abiraterone acetate tablets in patients with baseline severe hepatic impairment (Child-Pugh Class C).
Hepatotoxicity
For patients who develop hepatotoxicity during treatment with abiraterone acetate tablets (ALT and/or AST greater than 5X ULN or total bilirubin greater than 3X ULN), interrupt treatment with abiraterone acetate tablets [see Warnings and Precautions (5.3)]. Treatment may be restarted at a reduced dose of 750 mg once daily following return of liver function tests to the patient’s baseline or to AST and ALT less than or equal to 2.5X ULN and total bilirubin less than or equal to 1.5X ULN. For patients who resume treatment, monitor serum transaminases and bilirubin at a minimum of every two weeks for three months and monthly thereafter.
If hepatotoxicity recurs at the dose of 750 mg once daily, re-treatment may be restarted at a reduced dose of 500 mg once daily following return of liver function tests to the patient’s baseline or to AST and ALT less than or equal to 2.5X ULN and total bilirubin less than or equal to 1.5X ULN.
If hepatotoxicity recurs at the reduced dose of 500 mg once daily, discontinue treatment with abiraterone acetate tablets.
Permanently discontinue abiraterone acetate tablets for patients who develop a concurrent elevation of ALT greater than 3 x ULN and total bilirubin greater than 2 x ULN in the absence of biliary obstruction or other causes responsible for the concurrent elevation [see Warnings and Precautions (5.3)].
2.5 Dose Modification Guidelines For Strong Cyp3a4 Inducers
Avoid concomitant strong CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin, rifabutin, rifapentine, phenobarbital) during abiraterone acetate tablets treatment.
If a strong CYP3A4 inducer must be co-administered, increase the abiraterone acetate tablets dosing frequency to twice a day only during the co-administration period (e.g., from 1,000 mg once daily to 1,000 mg twice a day). Reduce the dose back to the previous dose and frequency, if the concomitant strong CYP3A4 inducer is discontinued [see Drug Interactions (7.1) and Clinical Pharmacology (12.3)].
3 Dosage Forms And Strengths
Abiraterone acetate tablets 250 mg are white to off-white, oval-shaped tablets debossed with "WW597" on one side.
4 Contraindications
Pregnancy
Abiraterone acetate tablets can cause fetal harm and potential loss of pregnancy [see Use in Specific Populations (8.1)].
5.1 Hypertension, Hypokalemia And Fluid Retention Due To Mineralocorticoid Excess
Abiraterone acetate may cause hypertension, hypokalemia, and fluid retention as a consequence of increased mineralocorticoid levels resulting from CYP17 inhibition [see Clinical Pharmacology (12.1)]. Monitor patients for hypertension, hypokalemia, and fluid retention at least once a month. Control hypertension and correct hypokalemia before and during treatment with abiraterone acetate.
In the combined data from 4 placebo-controlled trials using prednisone 5 mg twice daily in combination with 1000 mg abiraterone acetate daily, grades 3-4 hypokalemia were detected in 4% of patients on the abiraterone acetate arm and 2% of patients on the placebo arm. Grades 3-4 hypertension were observed in 2% of patients each arm and grades 3-4 fluid retention in 1% of patients each arm.
Closely monitor patients whose underlying medical conditions might be compromised by increases in blood pressure, hypokalemia or fluid retention, such as those with heart failure, recent myocardial infarction, cardiovascular disease, or ventricular arrhythmia. The safety of abiraterone acetate in patients with left ventricular ejection fraction <50% or New York Heart Association (NYHA) Class III or IV heart failure (in COU-AA-301) or NYHA Class II to IV heart failure (in COU-AA-302) has not been established because these patients were excluded from these randomized clinical trials [see Clinical Studies (14)].
5.2 Adrenocortical Insufficiency
Adrenal insufficiency occurred in 0.3% of 2230 patients taking abiraterone acetate and in 0.1% of 1763 patients taking placebo in the combined data of randomized, placebo-controlled clinical studies. Adrenocortical insufficiency was reported in patients receiving abiraterone acetate in combination with prednisone, following interruption of daily steroids and/or with concurrent infection or stress.
Monitor patients for symptoms and signs of adrenocortical insufficiency, particularly if patients are withdrawn from prednisone, have prednisone dose reductions, or experience unusual stress.
Symptoms and signs of adrenocortical insufficiency may be masked by adverse reactions associated with mineralocorticoid excess seen in patients treated with abiraterone acetate. If clinically indicated, perform appropriate tests to confirm the diagnosis of adrenocortical insufficiency. Increased dosage of corticosteroids may be indicated before, during and after stressful situations [see Warnings and Precautions (5.1)].
5.3 Hepatotoxicity
In postmarketing experience, there have been abiraterone acetate-associated severe hepatic toxicity, including fulminant hepatitis, acute liver failure and deaths [see Adverse Reactions (6.2)].
In the combined data of randomized clinical trials, grade 3-4 ALT or AST increases (at least 5X ULN) were reported in 6% of 2230 patients who received abiraterone acetate, typically during the first 3 months after starting treatment. Patients whose baseline ALT or AST were elevated were more likely to experience liver test elevation than those beginning with normal values. Treatment discontinuation due to ALT and AST increases or abnormal hepatic function occurred in 1.1% of 2230 patients taking abiraterone acetate. In these clinical trials, no deaths clearly related to abiraterone acetate were reported due to hepatotoxicity events.
Measure serum transaminases (ALT and AST) and bilirubin levels prior to starting treatment with abiraterone acetate, every two weeks for the first three months of treatment and monthly thereafter. In patients with baseline moderate hepatic impairment receiving a reduced abiraterone acetate dose of 250 mg, measure ALT, AST, and bilirubin prior to the start of treatment, every week for the first month, every two weeks for the following two months of treatment and monthly thereafter. Promptly measure serum total bilirubin, AST, and ALT if clinical symptoms or signs suggestive of hepatotoxicity develop. Elevations of AST, ALT, or bilirubin from the patient’s baseline should prompt more frequent monitoring. If at any time AST or ALT rise above five times the ULN, or the bilirubin rises above three times the ULN, interrupt abiraterone acetate treatment and closely monitor liver function.
Re-treatment with abiraterone acetate at a reduced dose level may take place only after return of liver function tests to the patient’s baseline or to AST and ALT less than or equal to 2.5X ULN and total bilirubin less than or equal to 1.5X ULN [see Dosage and Administration (2.4)].
Permanently discontinue abiraterone acetate for patients who develop a concurrent elevation of ALT greater than 3 x ULN and total bilirubin greater than 2 x ULN in the absence of biliary obstruction or other causes responsible for the concurrent elevation [see Dosage and Administration (2.4)].
The safety of abiraterone acetate re-treatment of patients who develop AST or ALT greater than or equal to 20X ULN and/or bilirubin greater than or equal to 10X ULN is unknown.
6 Adverse Reactions
The following are discussed in more detail in other sections of the labeling:
• Hypertension, Hypokalemia, and Fluid Retention due to Mineralocorticoid Excess [see Warnings and Precautions (5.1)].
• Adrenocortical Insufficiency [see Warnings and Precautions (5.2)].
• Hepatotoxicity [see Warnings and Precautions (5.3)].
6.1 Clinical Trial Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
Two randomized placebo-controlled, multicenter clinical trials (COU-AA-301 and COU-AA-302) enrolled patients who had metastatic CRPC in which abiraterone acetate was administered orally at a dose of 1,000 mg daily in combination with prednisone 5 mg twice daily in the active treatment arms. Placebo plus prednisone 5 mg twice daily was given to patients on the control arm. Another randomized placebo-controlled, multicenter clinical trial enrolled patients who had another indication in which abiraterone acetate was administered in combination with prednisone. Placebos were administered to patients in the control arm. Additionally, two other randomized, placebo-controlled trials were conducted in patients with metastatic CRPC. The safety data pooled from 2230 patients in randomized controlled trials constitute the basis for the data presented in the Warnings and Precautions, Grade 1-4 adverse reactions, and Grade 1-4 laboratory abnormalities. In all trials, a gonadotropin-releasing hormone (GnRH) analog or prior orchiectomy was required in both arms.
In the pooled data, median treatment duration was 11 months (0.1, 43) for abiraterone acetate-treated patients and 7.2 months (0.1, 43) for placebo-treated patients. The most common adverse reactions (≥10%) that occurred more commonly (>2%) in the abiraterone acetate arm were fatigue, arthralgia, hypertension, nausea, edema, hypokalemia, hot flush, diarrhea, vomiting, upper respiratory infection, cough, and headache. The most common laboratory abnormalities (>20%) that occurred more commonly (≥2%) in the abiraterone acetate arm were anemia, elevated alkaline phosphatase, hypertriglyceridemia, lymphopenia, hypercholesterolemia, hyperglycemia, and hypokalemia. Grades 3-4 adverse events were reported for 53% of patients in the abiraterone acetate arm and 46% of patients in the placebo arm. Treatment discontinuation was reported in 14% of patients in the abiraterone acetate arm and 13% of patients in the placebo arm. The common adverse events (≥1%) resulting in discontinuation of abiraterone acetate and prednisone were hepatotoxicity and cardiac disorders.
Deaths associated with treatment-emergent adverse events were reported for 7.5% of patients in the abiraterone acetate arm and 6.6% of patients in the placebo arm. Of the patients in the abiraterone acetate arm, the most common cause of death was disease progression (3.3%). Other reported causes of death in ≥5 patients included pneumonia, cardio-respiratory arrest, death (no additional information), and general physical health deterioration.
6.2 Postmarketing Experience
The following additional adverse reactions have been identified during post approval use of abiraterone acetate with prednisone. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Respiratory, Thoracic and Mediastinal Disorders: non-infectious pneumonitis.
Musculoskeletal and Connective Tissue Disorders: myopathy, including rhabdomyolysis.
Hepatobiliary Disorders: fulminant hepatitis, including acute hepatic failure and death.
7.1 Drugs That Inhibit Or Induce Cyp3a4 Enzymes
Based on in vitro data, abiraterone acetate is a substrate of CYP3A4.
In a dedicated drug interaction trial, co-administration of rifampin, a strong CYP3A4 inducer, decreased exposure of abiraterone by 55%. Avoid concomitant strong CYP3A4 inducers during abiraterone acetate treatment. If a strong CYP3A4 inducer must be co-administered, increase the abiraterone acetate dosing frequency [see Dosage and Administration (2.5) and Clinical Pharmacology (12.3)].
In a dedicated drug interaction trial, co-administration of ketoconazole, a strong inhibitor of CYP3A4, had no clinically meaningful effect on the pharmacokinetics of abiraterone [see Clinical Pharmacology (12.3)].
7.2 Effects Of Abiraterone On Drug Metabolizing Enzymes
Abiraterone acetate is an inhibitor of the hepatic drug-metabolizing enzymes CYP2D6 and CYP2C8. In a CYP2D6 drug-drug interaction trial, the Cmax and AUC of dextromethorphan (CYP2D6 substrate) were increased 2.8- and 2.9-fold, respectively, when dextromethorphan was given with abiraterone acetate 1,000 mg daily and prednisone 5 mg twice daily. Avoid co-administration of abiraterone acetate with substrates of CYP2D6 with a narrow therapeutic index (e.g., thioridazine). If alternative treatments cannot be used, consider a dose reduction of the concomitant CYP2D6 substrate drug [see Clinical Pharmacology (12.3)].
In a CYP2C8 drug-drug interaction trial in healthy subjects, the AUC of pioglitazone (CYP2C8 substrate) was increased by 46% when pioglitazone was given together with a single dose of 1,000 mg abiraterone acetate. Therefore, patients should be monitored closely for signs of toxicity related to a CYP2C8 substrate with a narrow therapeutic index if used concomitantly with abiraterone acetate [see Clinical Pharmacology (12.3)].
8 Use In Specific Populations
8.1 Pregnancy
Risk Summary
Based on findings from animal studies and the mechanism of action, abiraterone acetate is contraindicated for use in pregnant women because the drug can cause fetal harm and potential loss of pregnancy. Abiraterone acetate is not indicated for use in females.
There are no human data on the use of abiraterone acetate in pregnant women. In animal reproduction studies, oral administration of abiraterone acetate to pregnant rats during organogenesis caused adverse developmental effects at maternal exposures approximately ≥ 0.03 times the human exposure (AUC) at the recommended dose (see Data).
Data
Animal Data
In an embryo-fetal developmental toxicity study in rats, abiraterone acetate caused developmental toxicity when administered at oral doses of 10, 30 or 100 mg/kg/day throughout the period of organogenesis (gestational days 6-17). Findings included embryo-fetal lethality (increased post implantation loss and resorptions and decreased number of live fetuses), fetal developmental delay (skeletal effects) and urogenital effects (bilateral ureter dilation) at doses ≥10 mg/kg/day, decreased fetal ano-genital distance at ≥30 mg/kg/day, and decreased fetal body weight at 100 mg/kg/day. Doses ≥10 mg/kg/day caused maternal toxicity. The doses tested in rats resulted in systemic exposures (AUC) approximately 0.03, 0.1 and 0.3 times, respectively, the AUC in patients.
8.2 Lactation
Risk Summary
Abiraterone acetate is not indicated for use in women. There is no information available on the presence of abiraterone acetate in human milk, or on the effects on the breastfed child or milk production.
8.3 Females And Males Of Reproductive Potential
Contraception
Males
Based on findings in animal reproduction studies and its mechanism of action, advise males with female partners of reproductive potential to use effective contraception during treatment and for 3 weeks after the final dose of abiraterone acetate [see Use in Specific Populations (8.1)].
Infertility
Based on animal studies, abiraterone acetate may impair reproductive function and fertility in males of reproductive potential [see Nonclinical Toxicology (13.1)].
8.4 Pediatric Use
Safety and effectiveness of abiraterone acetate in pediatric patients have not been established.
8.5 Geriatric Use
Of the total number of patients receiving abiraterone acetate in randomized clinical trials, 70% of patients were 65 years and over and 27% were 75 years and over. No overall differences in safety or effectiveness were observed between these elderly patients and younger patients. Other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
8.6 Patients With Hepatic Impairment
The pharmacokinetics of abiraterone were examined in subjects with baseline mild (N=8) or moderate (N=8) hepatic impairment (Child-Pugh Class A and B, respectively) and in 8 healthy control subjects with normal hepatic function. The systemic exposure (AUC) of abiraterone after a single oral 1,000 mg dose of abiraterone acetate increased by approximately 1.1-fold and 3.6-fold in subjects with mild and moderate baseline hepatic impairment, respectively compared to subjects with normal hepatic function.
In another trial, the pharmacokinetics of abiraterone were examined in subjects with baseline severe (N=8) hepatic impairment (Child-Pugh Class C) and in 8 healthy control subjects with normal hepatic function. The systemic exposure (AUC) of abiraterone increased by approximately 7-fold and the fraction of free drug increased 2-fold in subjects with severe baseline hepatic impairment compared to subjects with normal hepatic function.
No dosage adjustment is necessary for patients with baseline mild hepatic impairment. In patients with baseline moderate hepatic impairment (Child-Pugh Class B), reduce the recommended dose of abiraterone acetate to 250 mg once daily. Do not use abiraterone acetate in patients with baseline severe hepatic impairment (Child-Pugh Class C). If elevations in ALT or AST >5X ULN or total bilirubin >3X ULN occur in patients with baseline moderate hepatic impairment, discontinue abiraterone acetate treatment [see Dosage and Administration (2.4) and Clinical Pharmacology (12.3)].
For patients who develop hepatotoxicity during treatment, interruption of treatment and dosage adjustment may be required [see Dosage and Administration (2.4), Warnings and Precautions (5.3), and Clinical Pharmacology (12.3)].
8.7 Patients With Renal Impairment
No dosage adjustment is necessary for patients with renal impairment [see Clinical Pharmacology (12.3)].
10 Overdosage
Human experience of overdose with abiraterone acetate tablets is limited.
There is no specific antidote. In the event of an overdose, stop abiraterone acetate tablets, undertake general supportive measures, including monitoring for arrhythmias and cardiac failure and assess liver function.
11 Description
Abiraterone acetate, the active ingredient of abiraterone acetate tablets, USP is the acetyl ester of abiraterone. Abiraterone is an inhibitor of CYP17 (17α-hydroxylase/C17,20-lyase). Each abiraterone acetate tablet, USP contains 250 mg of abiraterone acetate. Abiraterone acetate is designated chemically as (3β)-17-(3-pyridinyl) androsta-5,16-dien-3-yl acetate and its structure is:
Abiraterone acetate is a white to off-white, non-hygroscopic, crystalline powder. Its molecular formula is C26H33NO2 and it has a molecular weight of 391.55. Abiraterone acetate is a lipophilic compound with an octanol-water partition coefficient of 5.12 (Log P) and is practically insoluble in water. The pKa of the aromatic nitrogen is 5.19.
Abiraterone acetate tablets, USP are available in 250 mg uncoated tablets with the following inactive ingredients:
• 250 mg uncoated tablets: colloidal silicon dioxide, croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, povidone, sodium lauryl sulfate and sodium starch glycolate (derived from potato).
12.1 Mechanism Of Action
Abiraterone acetate is converted in vivo to abiraterone, an androgen biosynthesis inhibitor, that inhibits 17 α-hydroxylase/C17,20-lyase (CYP17). This enzyme is expressed in testicular, adrenal, and prostatic tumor tissues and is required for androgen biosynthesis.
CYP17 catalyzes two sequential reactions: 1) the conversion of pregnenolone and progesterone to their 17α-hydroxy derivatives by 17α-hydroxylase activity and 2) the subsequent formation of dehydroepiandrosterone (DHEA) and androstenedione, respectively, by C17, 20 lyase activity. DHEA and androstenedione are androgens and are precursors of testosterone. Inhibition of CYP17 by abiraterone can also result in increased mineralocorticoid production by the adrenals [see Warnings and Precautions (5.1)].
Androgen sensitive prostatic carcinoma responds to treatment that decreases androgen levels. Androgen deprivation therapies, such as treatment with GnRH agonists or orchiectomy, decrease androgen production in the testes but do not affect androgen production by the adrenals or in the tumor.
Abiraterone acetate decreased serum testosterone and other androgens in patients in the placebo-controlled clinical trial. It is not necessary to monitor the effect of abiraterone acetate on serum testosterone levels.
Changes in serum prostate specific antigen (PSA) levels may be observed but have not been shown to correlate with clinical benefit in individual patients.
12.3 Pharmacokinetics
Following administration of abiraterone acetate, the pharmacokinetics of abiraterone and abiraterone acetate have been studied in healthy subjects and in patients with metastatic castration-resistant prostate cancer (CRPC). In vivo, abiraterone acetate is converted to abiraterone. In clinical studies, abiraterone acetate plasma concentrations were below detectable levels (<0.2 ng/mL) in >99% of the analyzed samples.
12.6 Qt Prolongation
In a multi-center, open-label, single-arm trial, 33 patients with metastatic CRPC received abiraterone acetate orally at a dose of 1,000 mg once daily at least 1 hour before or 2 hours after a meal in combination with prednisone 5 mg orally twice daily. Assessments up to Cycle 2 Day 2 showed no large changes in the QTc interval (i.e., >20 ms) from baseline. However, small increases in the QTc interval (i.e., <10 ms) due to abiraterone acetate cannot be excluded due to study design limitations.
13.1 Carcinogenesis, Mutagenesis, And Impairment Of Fertility
A two-year carcinogenicity study was conducted in rats at oral abiraterone acetate doses of 5, 15, and 50 mg/kg/day for males and 15, 50, and 150 mg/kg/day for females. Abiraterone acetate increased the combined incidence of interstitial cell adenomas and carcinomas in the testes at all dose levels tested. This finding is considered to be related to the pharmacological activity of abiraterone. Rats are regarded as more sensitive than humans to developing interstitial cell tumors in the testes. Abiraterone acetate was not carcinogenic in female rats at exposure levels up to 0.8 times the human clinical exposure based on AUC. Abiraterone acetate was not carcinogenic in a 6-month study in the transgenic (Tg.rasH2) mouse.
Abiraterone acetate and abiraterone was not mutagenic in an in vitro microbial mutagenesis (Ames) assay or clastogenic in an in vitro cytogenetic assay using primary human lymphocytes or an in vivo rat micronucleus assay.
In repeat-dose toxicity studies in male rats (13- and 26-weeks) and monkeys (39-weeks), atrophy, aspermia/hypospermia, and hyperplasia in the reproductive system were observed at ≥50 mg/kg/day in rats and ≥250 mg/kg/day in monkeys and were consistent with the antiandrogenic pharmacological activity of abiraterone. These effects were observed in rats at systemic exposures similar to humans and in monkeys at exposures approximately 0.6 times the AUC in humans.
In a fertility study in male rats, reduced organ weights of the reproductive system, sperm counts, sperm motility, altered sperm morphology and decreased fertility were observed in animals dosed for 4 weeks at ≥30 mg/kg/day orally. Mating of untreated females with males that received 30 mg/kg/day oral abiraterone acetate resulted in a reduced number of corpora lutea, implantations and live embryos and an increased incidence of pre-implantation loss. Effects on male rats were reversible after 16 weeks from the last abiraterone acetate administration.
In a fertility study in female rats, animals dosed orally for 2 weeks until day 7 of pregnancy at ≥30 mg/kg/day had an increased incidence of irregular or extended estrous cycles and pre-implantation loss (300 mg/kg/day). There were no differences in mating, fertility, and litter parameters in female rats that received abiraterone acetate. Effects on female rats were reversible after 4 weeks from the last abiraterone acetate administration.
The dose of 30 mg/kg/day in rats is approximately 0.3 times the recommended dose of 1,000 mg/day based on body surface area.
In 13- and 26-week studies in rats and 13- and 39-week studies in monkeys, a reduction in circulating testosterone levels occurred with abiraterone acetate at approximately one half the human clinical exposure based on AUC. As a result, decreases in organ weights and toxicities were observed in the male and female reproductive system, adrenal glands, liver, pituitary (rats only), and male mammary glands. The changes in the reproductive organs are consistent with the antiandrogenic pharmacological activity of abiraterone acetate.
13.2 Animal Toxicology And/Or Pharmacology
A dose-dependent increase in cataracts was observed in rats after daily oral abiraterone acetate administration for 26 weeks starting at ≥50 mg/kg/day (similar to the human clinical exposure based on AUC). In a 39-week monkey study with daily oral administration, no cataracts were observed at higher doses (2 times greater than the clinical exposure based on AUC).
14 Clinical Studies
The efficacy and safety of abiraterone acetate with prednisone was established in three randomized placebo-controlled international clinical studies. All patients in these studies received a GnRH analog or had prior bilateral orchiectomy. Patients with prior ketoconazole treatment for prostate cancer and a history of adrenal gland or pituitary disorders were excluded from these trials. Concurrent use of spironolactone was not allowed during the study period.
COU-AA-301 (NCT00638690): Patients with metastatic CRPC who had received prior docetaxel chemotherapy
A total of 1195 patients were randomized 2:1 to receive either abiraterone acetate orally at a dose of 1,000 mg once daily in combination with prednisone 5 mg orally twice daily (N=797) or placebo once daily plus prednisone 5 mg orally twice daily (N=398). Patients randomized to either arm were to continue treatment until disease progression (defined as a 25% increase in PSA over the patient’s baseline/nadir together with protocol-defined radiographic progression and symptomatic or clinical progression), initiation of new treatment, unacceptable toxicity or withdrawal.
The following patient demographics and baseline disease characteristics were balanced between the treatment arms. The median age was 69 years (range 39–95) and the racial distribution was 93% Caucasian, 3.6% Black, 1.7% Asian, and 1.6% Other. Eighty-nine percent of patients enrolled had an ECOG performance status score of 0–1 and 45% had a Brief Pain Inventory-Short Form score of ≥4 (patient’s reported worst pain over the previous 24 hours). Ninety percent of patients had metastases in bone and 30% had visceral involvement. Seventy percent of patients had radiographic evidence of disease progression and 30% had PSA-only progression. Seventy percent of patients had previously received one cytotoxic chemotherapy regimen and 30% received two regimens.
The protocol pre-specified interim analysis was conducted after 552 deaths and showed a statistically significant improvement in overall survival (OS) in patients treated with abiraterone acetate with prednisone compared to patients in the placebo arm (Table 9 and Figure 1). An updated survival analysis was conducted when 775 deaths (97% of the planned number of deaths for final analysis) were observed. Results from this analysis were consistent with those from the interim analysis (Table 7).
16 How Supplied/Storage And Handling
Abiraterone Acetate Tablets, USP 250 mg – Uncoated tablets
Abiraterone acetate tablets, USP are available as white to off-white, oval tablets debossed with "WW597" on one side.
NDC 0143-9597-21 120 tablets available in high-density polyethylene bottles
17 Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (Patient Information)
Hypertension, Hypokalemia, and Fluid Retention
• Inform patients that abiraterone acetate tablets are associated with hypertension, hypokalemia, and peripheral edema. Advise patients to report symptoms of hypertension, hypokalemia, or edema to their healthcare provider [see Warnings and Precautions (5.1)].
Adrenocortical Insufficiency
• Inform patients that abiraterone acetate tablets with prednisone is associated with adrenal insufficiency. Advise patients to report symptoms of adrenocortical insufficiency to their healthcare provider [see Warnings and Precautions (5.2)].
Hepatotoxicity
• Inform patients that abiraterone acetate tablets are associated with severe hepatotoxicity. Inform patients that their liver function will be monitored using blood tests. Advise patients to immediately report symptoms of hepatotoxicity to their healthcare provider [see Warnings and Precautions (5.3)].
Dosing and Administration
• Inform patients that abiraterone is taken once daily with prednisone twice daily (according to their healthcare provider’s instructions) and to not interrupt or stop either of these medications without consulting their healthcare provider.
• Inform patients receiving GnRH therapy that they need to maintain this treatment during the course of treatment with abiraterone acetate tablets.
• Instruct patients to take abiraterone acetate tablets on an empty stomach, either one hour before or two hours after a meal. Abiraterone acetate tablets taken with food causes increased exposure and may result in adverse reactions. Instruct patients to swallow tablets whole with water and not to crush or chew the tablets [see Dosage and Administration (2.3)].
• Inform patients that if they miss a dose of abiraterone acetate tablets or prednisone, they should take their normal dose the following day. If more than one daily dose is skipped, inform patients to contact their healthcare provider [see Dosage and Administration (2.3)].
Fetal Toxicity
• Inform patients that abiraterone acetate tablets may harm a developing fetus. Advise males with female partners of reproductive potential to use effective contraception during treatment and for 3 weeks after the final dose of abiraterone acetate tablets [see Use in Specific Populations (8.1)].
• Women who are pregnant or women who may be pregnant should not handle abiraterone acetate 250 mg uncoated tablets if broken, crushed, or damaged without protection, e.g., gloves [see Use in Specific Populations (8.1) and How Supplied/Storage and Handling (16)].
Infertility
• Advise male patients that abiraterone acetate tablets may impair fertility [see Use in Specific Populations (8.3)].
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