VAL-1221 Delivered Intravenously in Ambulatory and Ventilator-free Participants With Late-Onset Pompe Disease

A Three-Month, Open-Label, Randomized, Dose-escalation Study of the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics and Preliminary Efficacy of VAL-1221 Versus Myozyme®/Lumizyme® in Patients With Late-Onset GSD-II (Pompe Disease) Followed by Open-Label Treatment With VAL-1221 in All Patients

This Phase I/II open-label, randomized, dose-escalation study will assess the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary efficacy of VAL-1221 versus Myozyme®/Lumizyme® in participants with late-onset glycogen storage disease-II (GSD-II) (Pompe disease)

Part 1 comprises 3 sequential cohorts of 4 patients each randomized to treatment with either VAL-1221 (at 3, 10, or 30 mg/kg) or positive control (rhGAA). Patients randomized to VAL-1221 will receive 7 intravenous (IV) infusions of VAL-1221 (one infusion every other week) over 12 weeks. Control patients will continue receiving their accustomed dose and regimen of Myozyme®. Part 2 is an uncontrolled extension to evaluate long-term effects of VAL-1221 given by IV infusion once every other week at doses up to 40 mg/kg.

Inclusion Criteria:

• Participant is able and willing to provide informed consent prior to any study procedures are performed

• Diagnosis of GSDII based on one of the following:

  • Endogenous cultured skin fibroblast GAA activity less than (<) 40 percent (%) of adult normal level
  • Endogenous whole blood or dried blood spot GAA activity in deficiency range
  • Genetic analysis showing pathogenic variants in both alleles

• Onset of Pompe disease-related symptoms after 1 year of age

• Previously treated with Myozyme or Lumizyme for at least 12 months and on a stable regimen for the past 6 months

• Sexually active participants who are willing to use an acceptable method of contraception (abstinence, oral contraceptives, barrier method with spermicide, surgical sterilization, implanted or injectable contraceptives with a stable dose for at least 1 month prior to Baseline, hormonal intra-uterine device [IUD] inserted at least 1 month prior to Baseline) during the study and for 30 days after completion of treatment

  • If participant is female and not considered to be of childbearing potential, she is at least 2 years post-menopause, has undergone a tubal ligation, a total hysterectomy or bilateral oophorectomy
  • If participant is female and of childbearing potential, she has a negative serum pregnancy test during screening and Baseline and must be willing to undergo pregnancy testing at specific intervals during the study

• Participant meets at least one of the following criteria: greater than (>) 30% and <80% predicted upright forced volume capacity (FVC) or participant is able to walk >20% but <80% predicted normal on 6-minute walk test with or without use of assistive devices

• Able to comply with protocol requirements

Exclusion Criteria:

• Cardiac involvement in first year of life
• Anti-GAA antibody titers >1:51,200 at two time points
• Prior use of chaperone therapy for GSD-II within the last 12 months
• Use of immunosuppressive medication other than glucocorticoids within 6 months prior to study enrollment
• Use of invasive ventilatory assistance other than Bilevel Positive Airway Pressure (BiPAP) at night or during periods of rest
• Has received any investigational medication or has enrolled in any study involving investigational drugs or therapies within 30 days prior to first dose of study drug
• Start of or change in usual regimen of albuterol or respiratory muscle training within 30 days prior to first dose of study drug
• History of sensitivity to any of the constituents of the study drug
• Participant is breastfeeding or planning to become pregnant or to breastfeed during the study or is currently breastfeeding
• Participant has a medical condition or circumstance that, in the opinion of the investigator, might compromise the participant's ability to comply with the protocol or the participant's well-being or safety
• Participant has any condition that, in the view of the investigator, places the participant at high risk of poor treatment compliance or of not completing the study