Isturisa Drug Information

ISTURISA is indicated for the treatment of endogenous hypercortisolemia in adults with Cushing's syndrome for whom surgery is not an option or has not been curative.

Laboratory Testing Prior to ISTURISA Initiation

Correct hypokalemia and hypomagnesemia prior to starting ISTURISA. Obtain baseline electrocardiogram (ECG). Repeat ECG within one week after treatment initiation, and as clinically indicated thereafter.

Recommended Dosage, Titration, and Monitoring

Initiate dosing at 2 mg orally twice daily, with or without food. Initially, titrate the dosage by 1 mg to 2 mg twice daily, no more frequently than every 2 weeks based on the rate of cortisol changes, individual tolerability and improvement in signs and symptoms of Cushing's syndrome. If a patient tolerates ISTURISA dosage of 10 mg twice daily and continues to have elevated 24-hour urine free cortisol (UFC) levels above upper normal limit, the dosage can be titrated further by 5 mg twice daily every 2 weeks.

Monitor cortisol levels from at least two 24-hour urine free cortisol collections every 1 to 2 weeks until adequate clinical response is maintained. The maintenance dosage of ISTURISA is individualized and determined by titration based on cortisol levels and patient's signs and symptoms. The maintenance dosage varied between 2 mg and 7 mg twice daily in clinical trials.

The maximum recommended maintenance dosage of ISTURISA is 30 mg twice daily. Once the maintenance dosage is achieved, monitor cortisol levels at least every 1 to 2 months or as indicated.

Dosage Interruptions and Modifications Decrease or temporarily discontinue ISTURISA if urine free cortisol levels fall below the target range, there is a rapid decrease in cortisol levels, and/or patients report symptoms of hypocortisolism. If necessary, glucocorticoid replacement therapy should be initiated. Stop ISTURISA and administer exogenous glucocorticoid replacement therapy if serum or plasma cortisol levels are below target range and patients have symptoms of adrenal insufficiency.

If treatment is interrupted, re-initiate ISTURISA at a lower dose when cortisol levels are within target ranges and patient symptoms have been resolved.

Recommended Dosage and Monitoring in Patients with Renal Impairment No dose adjustment is required for patients with renal impairment. Use caution in interpreting urine free cortisol levels in patients with moderate to severe renal impairment, due to reduced urine free cortisol excretion.

Recommended Dosage and Monitoring in Patients with Hepatic Impairment For patients with moderate hepatic impairment (Child-Pugh B), the recommended starting dose is 1 mg twice daily. For patients with severe hepatic impairment (Child-Pugh C), the recommended starting dose is 1 mg once daily in the evening. No dose adjustment is required for patients with mild hepatic impairment (Child-Pugh A).

More frequent monitoring of adrenal function may be required during dose titration in all patients with hepatic impairment.

Missed Dose If a dose of ISTURISA is missed, the patient should take their next dose at the regularly scheduled time.

Clinical Trials 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 clinical trials of another drug and may not reflect the rates observed in practice. The safety of ISTURISA was evaluated in two clinical trials in adults with Cushings disease. Study 1 (NCT02180217) was a 4-period, multicenter study with a 12-week open-label titration period, 12-week open-label maintenance period, 8-week double-blind, placebo-controlled period, and 14 to 24-week open label treatment period in 137 patients with Cushing's disease.

Study 2 (NCT02697734) was a 2-period, multicenter study with a 12-week randomized, double-blind, placebo-controlled period and a 36-week open-label treatment period in 74 patients with Cushing's disease. Study 1 The adverse reactions that occurred with frequency higher than 10% during the core 48-week period are shown in Table 1. Description of Select Adverse Reactions from the Core 48-week Period of Study 1 Gastrointestinal Disorders Gastrointestinal disorders, predominantly nausea, vomiting, diarrhea and abdominal pain were reported in 69% of patients.

In many cases, the episodes were of short duration (1-2 days) and the severity was mild to moderate. The majority of cases were manageable by reducing the dose of ISTURISA and/or adding low-dose, short-term glucocorticoid therapy. Eight patients discontinued because of an increase in tumor volume.

There was no correlation between tumor volume increase and increase in adrenocorticotrophic hormone (ACTH). There was no specific pattern of timing of the tumor volume increase and no relationship with the total and the last dose of ISTURISA used in the study. QTc Interval Prolongation Adverse reactions of QT prolongation and clinically relevant ECG findings were reported.

Accumulation of Adrenal Hormone Precursors CYP11B1 inhibition by ISTURISA is associated with adrenal steroid precursor accumulation and testosterone increases. The incidence of adverse reactions potentially related to accumulation of adrenal hormone precursors was 42%. Hypertension and hypokalemia were the most common adrenal hormone precursor-related adverse reactions and occurred in 14% of patients and 17% of patients, respectively; edema was reported in 7% of patients, elevated blood pressure in 15% of patients.

All cases of hypokalemia responded to treatment with potassium supplementation and/or mineralocorticoid antagonist therapy (e.g., spironolactone). One patient discontinued the study because of hypokalemia. In male patients testosterone levels generally increased but remained within normal limits; all patients were asymptomatic with no values above upper limit of normal (ULN) at last available value.

In female patients, mean testosterone levels increased above the normal range from baseline and reversed when treatment was interrupted. The testosterone increase was associated with mild to moderate cases of hirsutism (12%) or acne (11%) in a subset of female patients. Other Abnormal Laboratory Findings Decreased Absolute Neutrophil Count Of the 137 patients from the 48-week study 1, 18 patients had at least one measured absolute neutrophil count below the normal limit, 2 patients had an adverse reaction of neutropenia.

No concomitant infections and/or fever were reported in patients with decreased absolute neutrophil count. Elevated Liver Function Tests Liver enzyme elevations in patients treated with ISTURISA were infrequent, typically mild and reversed spontaneously or following dose adjustment. Most liver abnormal parameters occurred during the dose-titration period and no patients discontinued ISTURISA drug due to abnormal liver chemistry parameters.

Five (4%) patients had ALT or AST > 3 × ULN during the 48-week clinical study. Study 2 The adverse reactions that occurred with frequency higher than 10% and greater than placebo during the 12-week placebo controlled period are shown in Table 2. Table 2: Adverse Reactions With a Frequency of More Than 10% and Greater Than Placebo in the 12-week Placebo Controlled Period of Clinical Study 2 in Adults with Cushing's Disease 0 Description of Selected Adverse Reactions from the 12-week Placebo-Controlled Period of Study 2 Hypocortisolism Hypocortisolism was reported at a rate of 15% in ISTURISA arm and no subjects in placebo arm.

QTc Interval Prolongation One (2%) patient in ISTURISA arm had a new QTcF value of > 450ms versus none in placebo arm. Hypertension, blood testosterone increase, peripheral edema, acne and hypokalemia were the most common adrenal hormone precursor-related adverse reactions and occurred in of patients in ISTURISA arm, and in of patients in the placebo arm. Other Abnormal Laboratory Findings Decreased Absolute Neutrophil Count Three (6%) patients in ISTURISA arm had at least one measured absolute neutrophil count below the normal limit and one (2%) of these was classified as Grade 3 by Common Terminology Criteria for Adverse Events (CTCAEs) grading.

No patients in placebo arm had absolute neutrophil count below normal limit. No patient had concurrent increases in AST, ALT and total bilirubin and/or ALP. No patient met the criteria for Hy's Law.

Two (4%) patients in ISTURISA arm versus none in placebo arm had ALT or AST > 3 × ULN.

Postmarketing Experience

Additional adverse reactions have been identified during postapproval use of ISTURISA. Because these reactions are reported voluntarily from a population of uncertain size, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Neutropenia associated with fever and infection

Effect of Other Drugs on ISTURISA

The effect of other drugs on ISTURISA can be found in Table 3. Table 3: Effect of Other Drugs on ISTURISA CYP3A4 Inhibitors Clinical Impact: Concomitant use of ISTURISA with a strong CYP3A4 inhibitor (e.g., itraconazole, clarithromycin) may cause an increase in osilodrostat concentration and may increase the risk of ISTURISA-related adverse reactions. Intervention: Reduce the dose of ISTURISA by half with concomitant use of a strong CYP3A4 inhibitor.

CYP3A4 and CYP2B6 Inducers Clinical Impact: Concomitant use of ISTURISA with strong CYP3A4 and/or CYP2B6 inducers (e.g., carbamazepine, rifampin, phenobarbital) may cause a decrease in osilodrostat concentration and may reduce the efficacy of ISTURISA. Discontinuation of strong CYP3A4 and/or CYP2B6 inducers while using ISTURISA may cause an increase in osilodrostat concentration and may increase the risk of ISTURISA-related adverse reactions. Intervention: During concomitant use of ISTURISA with strong CYP3A4 and CYP2B6 inducers, monitor cortisol concentration and patient's signs and symptoms.

A reduction in ISTURISA dosage may be needed.

Effect of ISTURISA on Other Drugs ISTURISA should be used with caution when coadministered with CYP1A2 and CYP2C19 substrates with a narrow therapeutic index, such as theophylline, tizanidine, and S-mephenytoin.

Pregnancy Risk Summary There are no available data on osilodrostat use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. There are risks to the mother and fetus associated with active Cushing's Syndrome during pregnancy (see Clinical Considerations ). No adverse developmental outcomes were observed in reproduction studies in pregnant rats and rabbits when exposed to osilodrostat during organogenesis at doses that produced maternal exposures of 7 and 0.5-times the 30 mg twice daily maximum clinical dose, by AUC.

In rabbits, exposures associated with maternal toxicity at 7-times the maximum clinical dose resulted in decreased fetal viability. No adverse developmental outcomes were observed in a pre- and postnatal development study with administration of osilodrostat to pregnant rats from organogenesis through lactation at 8-times the 30 mg twice daily maximum clinical dose (see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown.

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Active Cushing Syndrome during pregnancy has been associated with an increased risk of maternal and fetal morbidity and mortality (including gestational diabetes, gestational hypertension, pre-eclampsia, maternal death, miscarriage, fetal loss, and preterm birth). Maternal toxicity, increased embryonic and fetal deaths, decreased fetal weights, and malformations occurred at 50 mg/kg (118-times the maximum clinical dose, by AUC).

Maternal toxicity, increased embryo resorption and decreased fetal viability was observed at ≥ 10mg/kg (7-times the maximum clinical dose, by AUC). Delayed parturition and dystocia in maternal rats and decreased pup survival were observed at 20 mg/kg (43-times the maximum clinical dose, by AUC).

Pediatric Use The safety and effectiveness of ISTURISA in pediatric patients have not been established.

Overdosage may result in severe hypocortisolism. Signs and symptoms suggestive of hypocortisolism may include nausea, vomiting, fatigue, low blood pressure, abdominal pain, loss of appetite, dizziness, and syncope. In case of suspected overdosage, ISTURISA should be temporarily discontinued, cortisol levels should be checked, and if necessary, corticosteroid supplementation should be initiated.

Close surveillance may be necessary, including monitoring of the QT interval, blood pressure, glucose, fluid, and electrolyte until the patient's condition is stable.