Mepsevii Drug Information

MEPSEVII is indicated in pediatric and adult patients for the treatment of Mucopolysaccharidosis VII (MPS VII, Sly syndrome). Limitations of Use The effect of MEPSEVII on the central nervous system manifestations of MPS VII has not been determined.

Recommended Dosage MEPSEVII should be administered under the supervision of a healthcare professional with the capability to manage anaphylaxis. Premedication is recommended 30 to 60 minutes prior to the start of the infusion. The recommended dosage of MEPSEVII is 4 mg/kg administered by intravenous infusion every two weeks.

Administer the infusion over approximately 4 hours. Infuse the first 2.5% of the total volume over the first hour. After the first hour, increase the infusion rate as tolerated in order to complete infusion over the following 3 hours according to the recommended rate guidelines in Table 1.

Follow the instructions in Table 1 for the rate of MEPSEVII infusion. Observe patients closely during the infusion and following the infusion for a minimum of 60 minutes for the development of anaphylaxis. Discontinue the infusion immediately if the patient experiences a severe systemic reaction, including anaphylaxis. 2. 3 Preparation Instructions Prepare MEPSEVII according to the following steps using aseptic technique: 1.

Determine the number of vials to be diluted based on the patient's actual weight and the recommended dose of 4 mg/kg, using the following calculations (a-b): a. Total dose (mg) = Patient's weight (kg) x 4 mg/kg (recommended dose) b. Total number of vials = Total dose (mg) divided by 10 mg/vial 2.

Round to the next whole vial and remove the required number of vials from the refrigerator to allow them to reach room temperature. Do not heat, microwave or shake vials. a. Volume (mL) of calculated dose = Total dose (mg) divided by the 2 mg/mL concentration 3.

The final solution will be a 1:1 dilution of MEPSEVII with 0.9% Sodium Chloride Injection, USP. More than 1:1 dilution may be used if the patient can tolerate additional infusion volume, taking into consideration cardiac function and fluid status. 4. For a 1:1 dilution, prepare the solution at room temperature, as follows: a.

Select an empty infusion bag, sized upon the total volume of the final solution. b. Prior to withdrawing MEPSEVII from the vial, visually inspect the solution for particulate matter and discoloration. Because this is a protein solution, slight flocculation (thin translucent fibers) may occur.

The MEPSEVII solution should be colorless to slightly yellow. Discard if the solution is discolored or if there is particulate matter in the solution. c. Slowly withdraw the volume of the calculated MEPSEVII dose from the appropriate number of vials (step 2a) using caution to avoid excessive agitation and any air or frothing.

Use a sufficiently large needle (18 gauge) to minimize bubbles in the solution. d. Slowly add MEPSEVII to the infusion bag using care to avoid agitation, ensuring liquid to liquid contact without generating bubbles or turbulence. e. Add 0.9% Sodium Chloride Injection, USP equal to the volume of MEPSEVII to the infusion bag. f.

Gently rock the infusion bag to ensure proper distribution of MEPSEVII. Do not shake the solution.

Administration Instructions Administer

Account for any dead space in the lines to ensure 2.5% of the total infusion volume is delivered into the patient's bloodstream during the first hour of infusion. Use an infusion set equipped with an in-line, low-protein binding 0.2 micron filter to administer the diluted MEPSEVII solution. Do not flush the line containing MEPSEVII to avoid a rapid bolus of infused enzyme.

Due to the low infusion rate, additional saline may be added through a separate line (piggyback or Y tube) to maintain sufficient intravenous flow to prevent clotting or line blockage. Do not infuse with other products in the infusion tubing. Compatibility with other products has not been evaluated.

Use MEPSEVII immediately after dilution and complete the infusion within 42 hours from the time of dilution. Discard any unused product. Stability If immediate use is not possible, the diluted solution may be stored up to 36 hours under refrigeration at 2°C to 8°C (36°F to 46°F) followed by up to 6 hours at room temperature up to a maximum of 25°C (77°F).

Table 1. Recommended Infusion Rate Schedule by Patient Weight for Administration of MEPSEVII at Recommended Dose of 4 mg/kg

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 the clinical trials of another drug and may not reflect the rates observed in practice. Nineteen patients were younger than 18 years of age. Adverse reactions in Table 2 occurred in one or more patients treated with MEPSEVII at a dosage of 4 mg/kg at a higher patient frequency than placebo.

Adverse reaction incidence rates are presented in the table below to account for the different duration of exposure to active treatment vs. placebo. The infusion was stopped, the patient received anticonvulsants, antipyretics and antibiotics, and the adverse reaction resolved. The patient subsequently was re-challenged without recurrence and continued on treatment.

Immunogenicity As with all therapeutic proteins, there is potential for immunogenicity. The detection of antibody formation is highly dependent on the sensitivity and specificity of the assay. Additionally, the observed incidence of antibody (including neutralizing antibody) positivity in an assay may be influenced by several factors including assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease.

For these reasons, comparison of the incidence of antibodies in the studies described below with the incidence of antibodies in other studies to other vestronidase alfa products may be misleading. Immunogenicity data were available from 23 patients who received MEPSEVII for up to 187 weeks of treatment. Eighteen out of 23 (78%) patients developed anti-vestronidase alfa-vjbk antibodies (ADA).

Ten of the 18 (55.6%) ADA-positive patients were tested positive for neutralizing antibodies (NAb). There is no correlation between ADA titer and NAb development. Six treatment-naïve patients had pre-existing ADA titers at baseline.

ADAs were detected in five of these six patients post-treatment. The post-treatment ADA titers were the same as or below the baseline ADA titer values in two patients, but one of these two patients was positive for NAb. ADA titer values after treatment increased 64-fold, 128-fold, and 364-fold, respectively, in the other three patients.

The presence of ADA titer did not appear to affect reduction in urinary glycosaminoglycans (uGAGs).

Pregnancy Risk Summary There are no available data on MEPSEVII use in pregnant women to determine a drug-associated risk of adverse developmental outcomes. In embryofetal development studies, vestronidase alfa-vjbk administered intravenously to pregnant rats and rabbits during the period of organogenesis showed no adverse developmental outcomes at doses up to 1.6 and 10 times, respectively for rats and rabbits, the exposure at the recommended human dose. In a pre- and post-natal development study in rats, an increased number of stillbirths were observed at exposures less than the recommended human dose (see Data).

The clinical relevance of these animal findings is uncertain. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes.

In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is respectively. Data Animal Data In embryofetal development studies, vestronidase alfa-vjbk administered intravenously to pregnant rats (once a week) and rabbits (once every 3 days) during the period of organogenesis showed no adverse developmental outcomes at doses up to 20 mg/kg. Mortality and adverse clinical signs were observed in the maternal animals at the 20 mg/kg dose (1.6 times the human exposure (AUC) at the recommended human dose of 4 mg/kg).

Subsequently, the 20 mg/kg dose was reduced to 12 mg/kg. Maternal toxicity with mortality in one animal was also observed at the 6 mg/kg dose (0.17 times the AUC at the recommended human dose of 4 mg/kg). At the 2 mg/kg dose (0.01 times the AUC at the recommended human dose of 4 mg/kg), no adverse effects were observed in the maternal animals; however, there was a statistically significant decrease in the number of live births and subsequent increase in the number of stillbirths at this dose.

8. 4 Pediatric Use The safety and effectiveness of MEPSEVII have been established in pediatric patients less than 18 years of age.