Biotech Values

[biomaven0]

Xtandi has additional benefits of more patient friendly administration, no prednisone requirement, and less physician monitoring of things like liver function.

Let's compare the AE labeling of the two drugs:

For Xtandi, we have a less than 1% chance of seizures, and the rest of the AE's were at a lower rate than placebo:

Grade 3 and higher adverse reactions were
reported among 47% of XTANDI-treated patients and 53% of placebo-treated patients. Discontinuations due to adverse
events were reported for 16% of XTANDI-treated patients and 18% of placebo-treated patients.

For Zytiga we have some significant cardiac and liver issue among others:

5 WARNINGS AND PRECAUTIONS
5.1 Hypertension, Hypokalemia and Fluid Retention Due to Mineralocorticoid
Excess
Use ZYTIGA with caution in patients with a history of cardiovascular disease. ZYTIGA
may cause hypertension, hypokalemia, and fluid retention as a consequence of increased
mineralocorticoid levels resulting from CYP17 inhibition [see Adverse Reactions (6) and
Clinical Pharmacology (12.1)]. Co-administration of a corticosteroid suppresses
adrenocorticotropic hormone (ACTH) drive, resulting in a reduction in the incidence and
severity of these adverse reactions. Use caution when treating patients whose underlying
medical conditions might be compromised by increases in blood pressure, hypokalemia or
fluid retention, e.g., those with heart failure, recent myocardial infarction or ventricular
arrhythmia. The safety of ZYTIGA in patients with left ventricular ejection fraction <50%
or NYHA Class III or IV heart failure has not been established because these patients were
excluded from the randomized clinical trial. Monitor patients for hypertension, hypokalemia,
Reference ID: 2939553
3 nd fluid retention at least once a month. Control hypertension and correct hypokalemia
before and during treatment with ZYTIGA.
5.2Adrenocortical Insufficiency
Adrenocortical insufficiency has been reported in clinical trials in patients receiving
ZYTIGA in combination with prednisone, following interruption of daily steroids and/or
with concurrent infection or stress. Use caution and monitor 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adrenocortical insufficiency, particularly if patients are withdrawn from prednisone, have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 ZYTIGA. 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)].
5.3Hepatotoxicity
Marked increases in liver enzymes leading to drug discontinuation or dosage modification
have occurred [see Adverse Reactions (6)]. Measure serum transaminases (ALT and AST)
and bilirubin levels prior to starting treatment with ZYTIGA, every two weeks for the first
three months of treatment and monthly thereafter. In patients with baseline moderate hepatic
impairment receiving a reduced ZYTIGA 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 ZYTIGA treatment and closely monitor
liver function.
Re-treatment with ZYTIGA 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 (2.2)].
The safety of ZYTIGA 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.

There is also a dramatic food effect:

Abiraterone Cmax and AUC0-8 (exposure) were increased up to 17- and
10-fold higher, respectively, when a single dose of abiraterone acetate was administered
with a meal compared to a fasted state.