• 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
    • Underlying disease

For these reasons, comparison of the incidence of antibodies to MEPSEVII with the incidence of antibodies to other products may be misleading.

Immunogenicity data were available from 23 patients

  • 18/23 patients (78%) developed anti-vestronidase alfa-vjbk antibodies (ADA)  

    • 10/18 (55.6%) ADA-positive patients developed neutralizing antibodies (NAb) on at least one occasion

      • There is no correlation between ADA titer and NAb development

  • 6 treatment-naïve patients had pre-existing ADA titers at baseline

    • ADAs were detected in 5/6 patients post-treatment

      • The post-treatment ADA titers were the same as or below the baseline ADA titer values in 2 patients, but 1 of these 2 patients was positive for NAb

      • ADA titer values after treatment increased 64-fold in 2 patients and 364-fold in the third patient    

  • The presence of ADA titer does not appear to affect reduction in the pharmacodynamic marker, urinary glycosaminoglycans (uGAGs), as assessed in clinical trials

MEPSEVII is a recombinant human lysosomal beta glucuronidase 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.



  • Anaphylaxis has occurred with MEPSEVII administration, as early as the first dose, therefore appropriate medical support should be readily available when MEPSEVII is administered.
  • Closely observe patients during and for 60 minutes after MEPSEVII infusion.
  • Immediately discontinue the MEPSEVII infusion if the patient experiences anaphylaxis.
  • Anaphylaxis to MEPSEVII was reported in 2 of 20 patients in the clinical program. The two patients with anaphylaxis to MEPSEVII during the clinical trials had one occurrence each and tolerated subsequent infusions of MEPSEVII, without recurrence.
  • Consider the risks and benefits of re-administering MEPSEVII following anaphylaxis.
  • Manifestations included respiratory distress, cyanosis, decreased oxygen saturation, and hypotension.
  • Prior to discharge, inform patients of the signs and symptoms of anaphylaxis and instruct them to seek immediate medical care if symptoms occur.

Adverse Reactions

  • In a clinical trial, the most common adverse reactions occurring with MEPSEVII treatment included infusion site extravasation, diarrhea, rash, anaphylaxis, infusion site swelling, peripheral swelling, and pruritus.
  • One patient experienced a febrile convulsion during MEPSEVII treatment. The patient subsequently was re-challenged without recurrence and continued on treatment.

Use in Specific Populations

  • There are no available data on MEPSEVII use in pregnant women to determine a drug-associated risk of adverse developmental outcomes.
  • There are no data on the presence of MEPSEVII in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for MEPSEVII and any potential adverse effects on the breastfed infant from MEPSEVII or from the underlying maternal condition.

You may report side effects to the FDA at (800) FDA-1088 or You may also report side effects to Ultragenyx at 1-888-756-8657.
Please see full Prescribing Information, including the BOXED WARNING, for a complete discussion of the risks associated with MEPSEVII.