U.S. Food & Drug Administration (FDA) Clinical Pharmacology Corner Update: FDA Approves COTELLIC (Cobimetinib)

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*FDA Approves COTELLIC^® (Cobimetinib) for the Treatment of Patients with Unresectable or Metastatic Melanoma with a BRAF V600E or V600K Mutation, in Combination with Vemurafenib *

On November 10, 2015, the United States Food and Drug Administration (FDA) approved COTELLIC (Cobimetinib) in combination with vemurafenib for the treatment of patients with unresectable or metastatic melanoma with a BRAF V600E or V600K Mutation. The approved recommended dosage of COTELLIC tablets is 60 mg orally once daily with or without food for the first 21 days of each 28 day cycle until disease progression or unacceptable toxicity. The dosage of COTELLIC may be reduced to 40 mg or 20 mg once daily for adverse reactions. Clinically relevant QT prolongation has been reported with vemurafenib, further QTc prolongation was not observed when cobimetinib 60 mg daily was co-administered with vemurafenib. Monitor ECG and electrolytes before initiating treatment and routinely during treatment with cobimetinib, when administered with vemurafenib.

_Mechanism of Action (MOA), General Pharmacokinetics (PK) and Pharmacodynamics (PD) of Cobimetinib_

* /MOA:/ Cobimetinib reversibly inhibits mitogen-activated protein kinase (MAPK)/extracellular signal regulated kinase 1 (MEK1) and MEK2. * /Dose proportionality:/ Exhibited dose-proportional increases in systemic exposure over the dose range of 3.5 to 100 mg (i.e., 0.06 to 1.7 times the approved recommended dosage).
* /Accumulation:/ Mean of 2.4-fold at the approved recommended dosage. * /Absorption:/ The absolute bioavailability of COTELLIC was 46% in healthy subjects. The Tmax was 2.4 hours (range:1 to 24 hours) in cancer patients.
* /Plasma protein binding:/ Approximately 95%.
* /Terminal half-life (mean):/ Approximately 44 hours (range: 23 to 70 hours) in cancer patients.
* /Metabolism:/ Primarily metabolized by CYP3A and glucuronidated by UGT2B7.
* /Excretion:/ Approximately 76% of the total recovered radio-labeled cobimetinib dose was eliminated in the feces (with 6.6% as unchanged drug) and 17.8% was eliminated in the urine (with 1.6% as unchanged drug).

_Drug Interaction Potential_

* Avoid strong or moderate CYP3A inhibitors. If concurrent short term (14 days or less) use of moderate CYP3A inhibitors including certain antibiotics (e.g., erythromycin, ciprofloxacin) is unavoidable for patients who are taking COTELLIC 60 mg, reduce COTELLIC dose to 20 mg. After discontinuation of a moderate CYP3A inhibitor, resume COTELLIC at the previous dose. Use an alternative to a strong or moderate CYP3A inhibitor in patients who are taking a reduced dose of COTELLIC (40 or 20 mg daily). Coadministration of the strong CYP3A inhibitor itraconazole increased cobimetinib AUC by 6.7-fold and Cmax by 3.2-fold.
* Avoid strong or moderate CYP3A inducers. Cobimetinib exposures are estimated to decrease by 83% when coadministered with a strong CYP3A inducer and by 73% when coadministered with a moderate CYP3A inducer. * Cobimetinib is a substrate of efflux transporter P-glycoprotein (P-gp) in vitro. Drugs that inhibit P-gp may increase cobimetinib concentrations; however, the clinical relevance of this finding is unknown.
* Clinically relevant pharmacokinetic interactions were not observed following coadministration of COTELLIC with the following medications: vemurafenib, midazolam (sensitive CYP3A substrate), dextromethorphan (sensitive CYP2D6 substrate), or rabeprazole (proton pump inhibitor).

_Use in Specific Populations_

The following population characteristics were not associated with a clinically significant effect on the pharmacokinetics of cobimetinib: sex, age (19 to 88 years), race/ethnicity, mild to moderate renal impairment (creatinine clearance [CLcr] 30 to 89 mL/min), and mild hepatic impairment (total bilirubin ≤ upper limit of normal [ULN] and AST > ULN or total bilirubin > ULN but ≤ 1.5 × ULN and any AST). The effect of moderate to severe hepatic impairment (total bilirubin > 1.5 to 3 × ULN and any AST), severe renal impairment or end-stage renal disease with or without hemodialysis (CLcr less than 29 mL/min) on cobimetinib exposure (i.e., AUC and Cmax) is unknown.

_Safety and Efficacy_

Clinical effectiveness and safety of cobimetinib were demonstrated at the approved recommended dosage in a multicenter, randomized (1:1), double-blinded, placebo-controlled trial in patients with previously untreated, BRAF V600 mutation-positive, unresectable or metastatic, melanoma. The median progression-free survival (PFS) was 12.3 months in patients treated with cobimetinib and vemurafenib compared with 7.2 months in those receiving vemurafenib as a single agent [hazard ratio: 0.56 (0.45, 0.70, p < 0.001)].

The most common adverse reactions were diarrhea, photosensitivity reaction, nausea, and vomiting. Advise patients to avoid sun exposure. Monitor for severe skin rashes and interrupt, reduce, or discontinue COTELLIC if required.