6 ADVERSE REACTIONS

The following are discussed in more detail in other sections of the labeling:

Hypokalemia, Fluid Retention, and Cardiovascular Adverse Reactions 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)].
Increased Fractures and Mortality in Combination with Radium Ra 223 Dichloride [see Warnings and Precautions (5.4)].

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 (Study 1 and Study 2) enrolled patients who had metastatic castration-resistant prostate cancer who were using a gonadotropin-releasing hormone (GnRH) agonist or were previously treated with orchiectomy. In both Study 1 and Study 2 abiraterone acetate was administered at a dose equivalent to 500 mg of YONSA daily in combination with a different corticosteroid twice daily in the active treatment arms. Placebo plus corticosteroid was given to control patients.

The most common adverse drug reactions (>10%) reported in the two randomized clinical trials that occurred more commonly (>2%) in the abiraterone acetate arm were fatigue, joint swelling or discomfort, edema, hot flush, diarrhea, vomiting, cough, hypertension, dyspnea, urinary tract infection and contusion.

The most common laboratory abnormalities (>20%) reported in the two randomized clinical trials that occurred more commonly (≥2%) in the abiraterone acetate arm were anemia, elevated alkaline phosphatase, hypertriglyceridemia, lymphopenia, hypercholesterolemia, hyperglycemia, elevated AST, hypophosphatemia, elevated ALT and hypokalemia.

Study 1: Metastatic CRPC Following Chemotherapy

Study 1 enrolled 1195 patients with metastatic CRPC who had received prior docetaxel chemotherapy. Patients were not eligible if AST and/or ALT ≥ 2.5X ULN in the absence of liver metastases. Patients with liver metastases were excluded if AST and/or ALT > 5X ULN.

Table 1 shows adverse reactions on the abiraterone acetate arm in Study 1 that occurred with a ≥2% absolute increase in frequency compared to placebo or were events of special interest. The median duration of treatment with abiraterone acetate with a corticosteroid was 8 months.

Table 1: Adverse Reactions due to Abiraterone Acetate in Study 1

	Abiraterone Acetate with Corticosteroid(N=791)		Placebo with Corticosteroid (N=394)
System Organ Class Adverse Reaction	All Grades1 %	Grade 3-4 %	All Grades %	Grade 3-4 %
Musculoskeletal and connective tissue disorders
Joint swelling/ discomfort2	30	4.2	23	4.1
Muscle discomfort3	26	3.0	23	2.3
General Disorders
Edema4	27	1.9	18	0.8
Vascular Disorders
Hot Flush	19	0.3	17	0.3
Hypertension	8.5	1.3	6.9	0.3
Gastrointestinal Disorders
Diarrhea	18	0.6	14	1.3
Dyspepsia	6.1	0	3.3	0
Infections and infestations
Urinary tract infection	12	2.1	7.1	0.5
Upper respiratory tract infection	5.4	0	2.5	0
Respiratory, thoracic and mediastinal disorders
Cough	11	0	7.6	0
Renal and urinary disorders
Urinary frequency	7.2	0.3	5.1	0.3
Nocturia	6.2	0	4.1	0
Injury, poisoning and procedural complications
Fractures5	5.9	1.4	2.3	0
Cardiac disorders
Arrhythmia6	7.2	1.1	4.6	1.0
Chest pain or chest discomfort7	3.8	0.5	2.8	0
Cardiac failure8	2.3	1.9	1.0	0.3
1 Adverse events graded according to CTCAE version 3.0
2 Includes terms Arthritis, Arthralgia, Joint swelling, and Joint stiffness
3 Includes terms Muscle spasms, Musculoskeletal pain, Myalgia, Musculoskeletal discomfort, and Musculoskeletal stiffness
4 Includes terms Edema, Edema peripheral, Pitting edema, and Generalized edema
5 Includes all fractures with the exception of pathological fracture
6 Includes terms Arrhythmia, Tachycardia, Atrial fibrillation, Supraventricular tachycardia, Atrial tachycardia, Ventricular tachycardia, Atrial flutter, Bradycardia, Atrioventricular block complete, Conduction disorder, and Bradyarrhythmia
7 Includes terms Angina pectoris, Chest pain, and Angina unstable. Myocardial infarction or ischemia occurred more commonly in the placebo arm than in the abiraterone acetate arm (1.3% vs. 1.1% respectively).
8 Includes terms Cardiac failure, Cardiac failure congestive, Left ventricular dysfunction, Cardiogenic shock, Cardiomegaly, Cardiomyopathy, and Ejection fraction decreased

Table 2 shows laboratory abnormalities of interest from Study 1. Grade 3-4 low serum phosphorus (7%) and low potassium (5%) occurred at a greater than or equal to 5% rate in the abiraterone acetate with a corticosteroid arm.

Table 2: Laboratory Abnormalities of Interest in Study 1

	Abiraterone Acetate with Corticosteroid(N=791)		Placebo with Corticosteroid(N=394)
Laboratory Abnormality	All Grades %	Grade 3-4 %	All Grades %	Grade 3-4 %
Hypertriglyceridemia	63	0.4	53	0
High AST	31	2.1	36	1.5
Hypokalemia	28	5.3	20	1.0
Hypophosphatemia	24	7.2	16	5.8
High ALT	11	1.4	10	0.8
High Total Bilirubin	6.6	0.1	4.6	0

Study 2: Metastatic CRPC Prior to Chemotherapy

Study 2 enrolled 1088 patients with metastatic CRPC who had not received prior cytotoxic chemotherapy. Patients were ineligible if AST and/or ALT ≥ 2.5X ULN and patients were excluded if they had liver metastases.

Table 3 shows adverse reactions on the abiraterone acetate arm in Study 2 that occurred in ≥ 5% of patients with a ≥ 2% absolute increase in frequency compared to placebo. The median duration of treatment with abiraterone acetate with a corticosteroid was 13.8 months.

Table 3: Adverse Reactions in ≥5% of Patients on the Abiraterone Acetate Arm in Study 2

	Abiraterone Acetate with Corticosteroid(N=542)		Placebo with Corticosteroid(N=540)
System Organ Class Adverse Reaction	All Grades1 %	Grade 3-4 %	All Grades %	Grade 3-4 %
General Disorders
Fatigue	39	2.2	34	1.7
Edema2	25	0.4	21	1.1
Pyrexia	8.7	0.6	5.9	0.2
Musculoskeletal and connective tissue disorders
Joint swelling/ discomfort3	30	2.0	25	2.0
Groin Pain	6.6	0.4	4.1	0.7
Gastrointestinal Disorders
Constipation	23	0.4	19	0.6
Diarrhea	22	0.9	18	0.9
Dyspepsia	11	0.0	5.0	0.2
Vascular Disorders
Hot Flush	22	0.2	18	0.0
Hypertension	22	3.9	13	3.0
Respiratory, thoracic and mediastinal disorders
Cough	17	0.0	14	0.2
Dyspnea	12	2.4	9.6	0.9
Psychiatric Disorders
Insomnia	14	0.2	11	0.0
Injury, poisoning and procedural complications
Contusion	13	0.0	9.1	0.0
Falls	5.9	0.0	3.3	0.0
Infections and infestations
Upper respiratory tract infection	13	0.0	8.0	0.0
Nasopharyngitis	11	0.0	8.1	0.0
Renal and urinary disorders
Hematuria	10	1.3	5.6	0.6
Skin and subcutaneous tissue disorders
Rash	8.1	0.0	3.7	0.0
1 Adverse events graded according to CTCAE version 3.0
2 Includes terms Edema peripheral, Pitting edema, and Generalized edema
3 Includes terms Arthritis, Arthralgia, Joint swelling, and Joint stiffness

Table 4 shows laboratory abnormalities that occurred in greater than 15% of patients, and more frequently (>5%) in the abiraterone acetate arm compared to placebo in Study 2.

Table 4: Laboratory Abnormalities in > 15% of Patients in the Abiraterone Acetate Arm of Study 2

	Abiraterone Acetate with Corticosteroid(N=542)		Placebo with Corticosteroid(N=540)
Laboratory Abnormality	Grade 1-4 %	Grade 3-4 %	Grade 1-4 %	Grade 3-4 %
Hematology
Lymphopenia	38	8.7	32	7.4
Chemistry
Hyperglycemia1	57	6.5	51	5.2
High ALT	42	6.1	29	0.7
High AST	37	3.1	29	1.1
Hypernatremia	33	0.4	25	0.2
Hypokalemia	17	2.8	10	1.7
1 Based on non-fasting blood draws

Cardiovascular Adverse Reactions

In the combined data for studies 1 and 2, cardiac failure occurred more commonly in patients treated with abiraterone acetate compared to patients on the placebo arm (2.1% versus 0.7%). Grade 3-4 cardiac failure occurred in 1.6% of patients taking abiraterone acetate and led to 5 treatment discontinuations and 2 deaths. Grade 3-4 cardiac failure occurred in 0.2% of patients taking placebo. There were no treatment discontinuations and one death due to cardiac failure in the placebo group.

In Study 1 and 2, the majority of arrhythmias were grade 1 or 2. There was one death associated with arrhythmia and one patient with sudden death in the abiraterone acetate arms and no deaths in the placebo arms. There were 7 (0.5 %) deaths due to cardiorespiratory arrest in the abiraterone acetate arms and 3 (0.3 %) deaths in the placebo arms. Myocardial ischemia or myocardial infarction led to death in 3 patients in the placebo arms and 2 deaths in the abiraterone acetate arms.

6.2 Postmarketing Experience

The following additional adverse reactions have been identified during post approval use of abiraterone acetate with a different corticosteroid. 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.

Cardiac Disorders: QT prolongation and Torsades de Pointes (observed in patients who developed hypokalemia or had underlying cardiovascular conditions).

Immune System Disorders – Hypersensitivity: anaphylactic reactions (severe allergic reactions that include, but are not limited to difficulty swallowing or breathing, swollen face, lips, tongue or throat, or an itchy rash (urticaria)).