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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.
Vismodegib is a highly permeable compound with low aqueous solubility (BCS Class 2). 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.
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.
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.
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.
Pharmacokinetics in Specific Populations
Hepatic Impairment: The effect of hepatic impairment on the systemic exposure of vismodegib has not been studied.
Renal Impairment: The effect of renal impairment on the systemic exposure of vismodegib has not been studied.
Population pharmacokinetic analyses showed that weight (range: 41-140 kg), age (range: 26-89 years), creatinine clearance (range: 30 to 80 mL/min), and sex do not have a clinically meaningful influence on the systemic exposure of vismodegib.
In a thorough QTc study in 60 healthy subjects, there was no effect of therapeutic doses of ERIVEDGE on the QTc interval.
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.
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
(n = 33)
(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)||7.6||7.6|
|(95% CI5)||(5.6, NE4)||(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: 2/2/2012
This monograph has been modified to include the generic and brand name in many instances.
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