Sunitinib Malate (Page 5 of 10)

8.5 Geriatric Use

Of the 7527 patients with GIST, RCC (advanced and adjuvant), or pNET who received sunitinib, 32% were 65 years and older, and 7% were 75 years and older. Patients aged 65 years of age and older had a higher incidence of Grade 3 or 4 adverse reactions (67%) than younger patients (60%).

In the GIST study, 73 (30%) of the patients who received sunitinib were 65 years and older. In the mRCC study, 152 (41%) of patients who received sunitinib were 65 years and older. No overall differences in safety or effectiveness were observed between these patients and younger patients.

In the pNET study, 22 (27%) of the patients who received sunitinib were 65 years and older. Clinical studies of sunitinib did not include sufficient numbers of patients with pNET to determine if patients 65 years of age and older respond differently than younger patients.

8.6 Hepatic Impairment

No dose adjustment is required in patients with mild or moderate (Child-Pugh Class A or B) hepatic impairment [see Clinical Pharmacology (12.3)]. Sunitinib was not studied in patients with severe (Child-Pugh Class C) hepatic impairment.

8.7 Renal Impairment

No dose adjustment is recommended in patients with mild (CLcr 50 to 80 mL/min), moderate (CLcr 30 to < 50 mL/min), or severe (CLcr < 30 mL/min) renal impairment who are not on dialysis [see Clinical Pharmacology (12.3)].

No dose adjustment is recommended for patients with end-stage renal disease (ESRD) on hemodialysis [see Clinical Pharmacology (12.3)].

10 OVERDOSAGE

Treatment of overdose with sunitinib should consist of general supportive measures. There is no specific antidote for overdosage with sunitinib. If indicated, elimination of unabsorbed drug should be achieved by emesis or gastric lavage. Cases of accidental overdose have been reported; these cases were associated with adverse reactions consistent with the known safety profile of sunitinib, or without adverse reactions. In nonclinical studies, mortality was observed following as few as 5 daily doses of 500 mg/kg (3000 mg/m2) in rats. At this dose, signs of toxicity included impaired muscle coordination, head shakes, hypoactivity, ocular discharge, piloerection, and gastrointestinal distress. Mortality and similar signs of toxicity were observed at lower doses when administered for longer durations.

11 DESCRIPTION

Sunitinib is a kinase inhibitor present in sunitinib malate capsules as the malate salt. Sunitinib malate is described chemically as N-[2-(Diethylamino)ethyl]-5-[(Z)-(5-fluoro-1,2-dihydro-2-oxo-3H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamide, compound with (S)-2-hydroxybutanedioic acid. The molecular formula is C22 H27 FN4 O2 .C4 H6 O5 and the molecular weight is 532.57 Daltons.

The chemical structure of sunitinib malate is:

spl-sunitinib-malate-structure
(click image for full-size original)

Sunitinib malate is light yellow to brownish orange colored powder with a pKa of 8.95. The solubility of sunitinib malate in aqueous media over the range pH 1.2 to pH 6.8 is in the range of 12 to 70 mg/mL. The log of the distribution coefficient (octanol/water) at pH 7 is 5.2.

Sunitinib malate capsules are supplied as printed hard shell capsules containing 12.5 mg, 25 mg, 37.5 mg or 50 mg of sunitinib (equivalent to 16.7 mg, 33.4 mg, 50.1 mg, or 66.8 mg of sunitinib malate, respectively) together with croscarmellose sodium, magnesium stearate, mannitol and povidone (K-30) as inactive ingredients.

The reddish brown gelatin capsule shells contain ferric oxide red and titanium dioxide. The caramel gelatin capsule shells contain ferric oxide red, ferric oxide yellow, ferrosoferric oxide and titanium dioxide. The yellow gelatin capsule shells contain ferric oxide yellow and titanium dioxide. The white printing ink contains potassium hydroxide, shellac and titanium dioxide. The black printing ink contains ferrosoferric oxide, potassium hydroxide and shellac.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Sunitinib is a small molecule that inhibits multiple receptor tyrosine kinases (RTKs), some of which are implicated in tumor growth, pathologic angiogenesis, and metastatic progression of cancer. Sunitinib was evaluated for its inhibitory activity against a variety of kinases (> 80 kinases) and was identified as an inhibitor of platelet-derived growth factor receptors (PDGFRα and PDGFRβ), vascular endothelial growth factor receptors (VEGFR1, VEGFR2, and VEGFR3), stem cell factor receptor (KIT), Fms-like tyrosine kinase-3 (FLT3), colony stimulating factor receptor Type 1 (CSF-1R), and the glial cell-line derived neurotrophic factor receptor (RET). Sunitinib inhibition of the activity of these RTKs has been demonstrated in biochemical and cellular assays, and inhibition of function has been demonstrated in cell proliferation assays. The primary metabolite exhibits similar potency compared to sunitinib in biochemical and cellular assays.

Sunitinib inhibited the phosphorylation of multiple RTKs (PDGFRβ, VEGFR2, KIT) in tumor xenografts expressing RTK targets in vivo and demonstrated inhibition of tumor growth or tumor regression and/or inhibited metastases in some experimental models of cancer. Sunitinib demonstrated the ability to inhibit growth of tumor cells expressing dysregulated target RTKs (PDGFR, RET, or KIT) in vitro and to inhibit PDGFRβ-and VEGFR2-dependent tumor angiogenesis in vivo.

12.2 Pharmacodynamics

Cardiac Electrophysiology

Sunitinib can cause QT interval prolongation in a dose-dependent manner, which may lead to an increased risk for ventricular arrhythmias including Torsade de Pointes [see Warnings and Precautions (5.3)].

12.3 Pharmacokinetics

The pharmacokinetics of sunitinib and sunitinib malate have been evaluated in healthy subjects and in patients with solid tumors.

Sunitinib AUC and Cmax increase proportionately over a dose range of 25 mg to 100 mg (0.5 to 2 times the approved RDD of 50 mg). The pharmacokinetics were similar in healthy subjects and in patients with a solid tumor, including patients with GIST and RCC. No significant changes in the pharmacokinetics of sunitinib or the primary active metabolite were observed with repeated daily administration or with repeated cycles. With repeated daily administration, sunitinib accumulates 3- to 4-fold while the primary metabolite accumulates 7- to 10-fold. Steady-state concentrations of sunitinib and its primary active metabolite are achieved within 10 to 14 days. By Day 14, combined plasma concentrations of sunitinib and its active metabolite ranged from 63 to 101 ng/mL.

Absorption

Following oral administration of sunitinib, the time to maximum plasma concentration (Tmax ) ranged from 6 to 12 hours.

Effect of Food

The administration of a single dose of sunitinib 50 mg with a high-fat, high-calorie meal (consisting of approximately 150 protein calories and 500 to 600 fat calories) in healthy subjects had no clinically significant effect on sunitinib or active metabolites exposure.

Distribution

The apparent volume of distribution (Vd/F) for sunitinib is 2230 L. Binding of sunitinib and its primary active metabolite to human plasma protein in vitro is 95% and 90%, respectively, with no concentration dependence in the range of 100 to 4000 ng/mL.

Elimination

Following administration of a single oral dose in healthy subjects, the terminal half-lives of sunitinib and its primary active metabolite are approximately 40 to 60 hours and 80 to 110 hours, respectively. Sunitinib total oral clearance (CL/F) ranged from 34 to 62 L/h with an interpatient variability of 40%.

Metabolism

Sunitinib is metabolized primarily by CYP3A4 to its primary active metabolite, which is further metabolized by CYP3A4. The primary active metabolite comprises 23% to 37% of the total exposure. After a radiolabeled dose, sunitinib and its active metabolite were the major compounds identified in plasma, accounting for 92% of radioactivity.

Excretion

After a radiolabeled dose of sunitinib, approximately 61% of the dose was recovered in feces and 16% in urine.

Sunitinib and its primary active metabolite were the major compounds identified in urine and feces, representing 86% and 74% of radioactivity, respectively.

Specific Populations

No clinically significant differences in the pharmacokinetics of sunitinib or the primary active metabolite were observed based on age (18 to 84 years), body weight (34 to 168 kg), race (White, Black, or Asian), sex, Eastern Cooperative Oncology Group (ECOG) score, mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment.

Patients with Renal Impairment

No clinically significant differences in the pharmacokinetics of sunitinib or its active metabolite were predicted or observed in patients with mild (CLcr 50 to 80 mL/min), moderate (CLcr 30 to < 50 mL/min), or severe (CLcr < 30 mL/min) renal impairment who are not on dialysis, compared to patients with normal renal function (CLcr > 80 mL/min). Although sunitinib was not eliminated through hemodialysis, the sunitinib systemic exposure was 47% lower in patients with end stage renal disease (ESRD) on hemodialysis compared to patients with normal renal function.

Drug Interaction Studies

Clinical Studies

Effect of strong CYP3A4 inhibitors on sunitini b: Co-administration of a single sunitinib dose with ketoconazole (strong CYP3A4 inhibitor) increased the combined sunitinib and its active metabolite Cmax and AUC0-inf by 49% and 51%, respectively, in healthy subjects.

Effect of strong CYP3A4 inducers on sunitinib: Co-administration of a single sunitinib dose with rifampin (strong CYP3A4 inducer) reduced the combined sunitinib and its active metabolite Cmax and AUC0-inf by 23% and 46%, respectively in healthy subjects.

In Vitro Studies

In vitro studies in human hepatocytes and microsomes indicated that sunitinib and the primary active metabolite do not induce CYP1A2, CYP2E1, and CYP3A4/5, or inhibit CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4/5, and CYP4A9/11 at clinically relevant concentrations.

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