June 25, 2016
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Erivedge

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Erivedge




CLINICAL PHARMACOLOGY

Mechanism Of Action

Vismodegib is an inhibitor of the Hedgehog pathway. Vismodegib binds to and inhibits Smoothened, a transmembrane protein involved in Hedgehog signal transduction.

Pharmacodynamics

Cardiac Electrophysiology

The QTc interval was not affected by therapeutic doses of ERIVEDGE in a thorough QTc trial.

Pharmacokinetics

Absorption

The single dose absolute bioavailability of vismodegib is 31.8%. Absorption is saturable as evidenced by the lack of dose proportional increase in exposure after a single dose of 270 mg or 540 mg vismodegib. ERIVEDGE capsule may be taken without regard to meals because the systemic exposure of vismodegib at steady state is not affected by food.

Distribution

The volume of distribution of vismodegib ranges from 16.4 to 26.6 L. Vismodegib plasma protein binding in patients is greater than 99%. Vismodegib binds to both human serum albumin and alpha- 1-acid glycoprotein (AAG) and binding to AAG is saturable.

In a pharmacokinetic study, male patients (n=3) had an average concentration of vismodegib in semen on day 8 that was 6.5% of the average steady state concentration (Css) observed in plasma.

Metabolism

Greater than 98% of the total circulating drug-related components are the parent drug. Metabolic pathways of vismodegib in humans include oxidation, glucuronidation, and pyridine ring cleavage. The two most abundant oxidative metabolites recovered in feces are produced in vitro by recombinant CYP2C9 and CYP3A4/5.

Elimination

Vismodegib and its metabolites are eliminated primarily by the hepatic route with 82% of the administered dose recovered in the feces and 4.4% recovered in urine. The estimated elimination half-life (t½) of vismodegib is 4 days after continuous once-daily dosing and 12 days after a single dose.

Specific Populations

Hepatic Impairment: In a dedicated clinical study, the mean systemic exposure (AUC 0-24hr) of vismodegib was increased by 24% in patients with mild (n=8), 31% in patients with moderate (n=6) and decreased 14% in patients with severe (n=3) hepatic impairment when compared to patients with normal hepatic function (n=9) after 8 days of daily ERIVEDGE administration. The NCI Organ Dysfunction Working Group criteria for hepatic impairment were used in the study. Mild hepatic impairment was defined as normal total bilirubin and aspartate transaminase (AST) > upper limit of normal (ULN) or total bilirubin > 1.0 to 1.5 times ULN, moderate hepatic impairment as total bilirubin > 1.5 to 3.0 times ULN, and severe hepatic impairment as total bilirubin > 3.0 to 10.0 times ULN.

Renal Impairment: Renal excretion of vismodegib after oral administration of ERIVEDGE is low ( < 5%). The population pharmacokinetic analysis suggested no clinically relevant effect of renal impairment on the systemic exposure of vismodegib, based on pharmacokinetic data from patients with mild (CLcr 50 to 79 mL/min, n=58), and moderate (CLcr 30 to 49 mL/min, n=16) renal impairment.

Weight, Age, and Sex: The results of a population pharmacokinetic analysis suggested no clinically relevant effect of weight (range: 41-140 kg), age (range: 26-89 years), and sex on the systemic exposure of vismodegib.

Drug Interaction Studies

Effect of Drugs on Vismodegib: Coadministration of ERIVEDGE with fluconazole (a moderate CYP2C9 inhibitor and moderate CYP3A4 inhibitor) increased mean AUC0-24hr and steady-state concentrations of vismodegib by 1.3-fold in healthy subjects. A strong inhibitor of CYP3A4 and Pgp (itraconazole) or a proton pump inhibitor (rabeprazole) had no effect on the steady-state systemic exposure of vismodegib when coadministered with ERIVEDGE in healthy subjects.

Effects of Vismodegib on Other Drugs: Results of a drug interaction study conducted in cancer patients demonstrated that the systemic exposure of rosiglitazone (a CYP2C8 substrate) or oral contraceptives (ethinyl estradiol and norethindrone) is not altered when either drug is coadministered with vismodegib.

In vitro studies suggest that vismodegib is an inhibitor of CYP2C8, CYP2C9, CYP2C19 and the transporter BCRP and that vismodegib is not an inducer of CYP1A2, CYP2B6, or CYP3A.

Animal Toxicology

Neurologic effects characterized as limb or body tremors or twitching were observed in rats administered oral vismodegib for 4 weeks or longer at ≥ 50 mg/kg/day (approximately ≥ 0.4 times the AUC in patients at the recommended human dose). These observations resolved upon discontinuation of dosing and were not associated with microscopic findings.

Clinical Studies

A single, international, single-arm, multi-center, open-label, 2-cohort trial was conducted in 104 patients with either metastatic basal cell carcinoma (mBCC) (n = 33) or locally advanced BCC (laBCC) (n = 71). Patients with laBCC were required to have lesions that had recurred after radiotherapy, unless radiotherapy was contraindicated or inappropriate (e.g. Gorlin syndrome; limitations because of location of tumor or cumulative prior radiotherapy dose), and where the lesions were either unresectable or surgical resection would result in substantial deformity. Patients were to receive 150 mg vismodegib per day orally until disease progression or unacceptable toxicity.

The major efficacy outcome measure of the trial was objective response rate (ORR) as assessed by an independent review facility (IRF). In the mBCC cohort, tumor response was assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0. In the laBCC cohort, tumor response evaluation included measurement of externally assessable tumor (including scar) and assessment for ulceration in photographs, radiographic assessment of target lesions (if appropriate), and tumor biopsy. An objective response in laBCC required at least one of the following criteria and absence of any criterion for disease progression: (1) ≥ 30% reduction in lesion size [sum of the longest diameter (SLD)] from baseline in target lesions by radiographic assessment; (2) ≥ 30% reduction in SLD from baseline in externally visible dimension of target lesions; (3) complete resolution of ulceration in all target lesions. Complete response was defined as objective response (as defined above) with no residual BCC on sampling tumor biopsy. Disease progression was defined as any of the following: (1) ≥ 20% increase in the SLD from nadir in target lesions (either by radiography or by externally visible dimension); (2) new ulceration of target lesions persisting without evidence of healing for at least 2 weeks; (3) new lesions by radiographic assessment or physical examination; (4) progression of non-target lesions by RECIST.

Of the 104 patients enrolled, 96 patients were evaluable for ORR. Twenty-one percent of patients carried a diagnosis of Gorlin syndrome. The median age of the efficacy evaluable population was 62 years (46% were at least 65 years old), 61% male and 100% White. For the mBCC cohort (n = 33), 97% of patients had prior therapy including surgery (97%), radiotherapy (58%), and systemic therapies (30%). For the laBCC cohort (n = 63), 94% of patients had prior therapies including surgery (89%), radiotherapy (27%), and systemic/topical therapies (11%). The median duration of treatment was 10.2 months (range 0.7 to 18.7 months).

The key outcome measures are presented in Table 2, below.

Table 2: Objective Response Rate: Efficacy-Evaluable Patients1

  mBCC
(n = 33)
laBCC
(n = 63)
IRF2-Confirmed ORR, n (%) 10 (30.3) 27 (42.9)
(95% CI) (15.6, 48.2) (30.5, 56.0)
Complete response3 0 (0.0) 13 (20.6)
Partial response 10 (30.3) 14 (22.2)
Median Response Duration (months)(95% CI5) 7.6(5.6, NE4) 7.6(5.7, 9.7)
1Patients who received at least one dose of ERIVEDGE with independent pathologist-confirmed diagnosis of BCC
2IRF = Independent Review Facility
3For laBCC, complete response was defined as objective response with no residual BCC on sampling tumor biopsy.
4NE = Not estimable
5CI = Confidence Interval

Last reviewed on RxList: 4/27/2016
This monograph has been modified to include the generic and brand name in many instances.

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