Protocol AGLU01602: A Randomized, Open-Label, Multicenter, Multinational, Dose-Ranging Study of the Safety, Efficacy, Pharmacokinetics, and Pharmacodynamics of Recombinant Human Acid alpha-Glucosidase (rhGAA) Treatment in Patients ≤ 6 Months Old with Infantile-Onset Pompe Disease (Glycogen Storage Disease Type II)

Myozyme^® (Alglucosidase alfa)

Drug Name	Generic Name	Studied Indications or Disease	Approved U.S. Drug Label
Myozyme®	Alglucosidase alfa	LSD Therapeutics Myozyme® (alglucosidase alfa) is indicated for use in patients with Pompe disease (GAA deficiency). Myozyme® has been shown to improve ventilator-free survival in patients with infantile-onset Pompe disease as compared to an untreated historical control, whereas use of Myozyme® in patients with other forms of Pompe disease has not been adequately studied to assure safety and efficacy	Prescribing Info

These results are supplied for informational purposes only.
Prescribing decisions should be made based on the approved package insert.

NAME OF SPONSOR/COMPANY

Genzyme Corporation, 500 Kendall Street, Cambridge, MA 02142

INVESTIGATORS AND STUDY CENTER(S)

This was a multicenter study that was conducted at thirteen investigational sites (6 in the USA, 5 in Europe, 1 in Israel, and 1 in Taiwan).

PUBLICATION (REFERENCE)

Publications

STUDIED PERIOD

26-May-2003 to 15-June-2005. Data were collected until the last patient randomized had been treated with Myozyme® for 52 weeks. For the invasive ventilator-free survival, ventilator-free survival, and survival endpoints, data are included up to 18 months of age. Survival and ventilation status at the end of the study period are also reported. For all other efficacy variables, data are included up to 52 weeks of treatment. Safety data were collected up to the end of the study.

PHASE OF DEVELOPMENT

Phase 2/3

OBJECTIVES

The overall objective was to evaluate the safety, efficacy, pharmacokinetics and pharmacodynamics of Myozyme® treatment in patients with infantile-onset Pompe disease in 2 dose groups.

The primary objectives were: (1) to evaluate the safety profile of Myozyme®; (2) to estimate, using Kaplan-Meier methodology, the proportion of patients treated with Myozyme® who were alive and free of invasive ventilator support at 18 months of age, and compare the combined dose groups to a historical control subgroup; (3) to determine the PK/PD profile of Myozyme® in patients with infantile-onset Pompe disease as measured by rhGAA levels (i.e., enzyme activity) in plasma and GAA activity and glycogen depletion in quadriceps muscle tissue as measured by biochemical and histomorphometric assessment; and (4) to determine the effect of different doses of Myozyme® on safety and efficacy outcomes.

Secondary objectives were: (1) to estimate, using Kaplan-Meier methodology, the proportion of patients treated with Myozyme® who were alive and free of invasive ventilator support at 12 months of age, and compare the combined dose groups to a historical control subgroup; (2) to estimate (using Kaplan-Meier methodology) the proportion of patients treated with Myozyme® who were alive and free of any ventilatory support (invasive or non-invasive) at 18 months of age as compared to the estimate of the proportion of patients alive at 18 months of age in a historical cohort; (3) to determine the effect of 52 weeks of Myozyme® treatment on (a) cardiac status as measured by the change in left ventricular mass index (LVMI); and (b) physical growth as measured by body length and weight.

Tertiary objectives of the analysis were: (1) to estimate the proportion of patients treated with Myozyme® who were alive at 18 months of age; (2) to determine the effects of 52 weeks of Myozyme® treatment on: (a) any signs and/or symptoms of cardiac failure; (b) motor development as measured by Alberta Infant Motor Scale (AIMS) scores and the number of motor development milestones achieved; (c) change in functional status as measured by the Pediatric Evaluation of Disability Inventory (PEDI) and Pompe PEDI; (d) cognitive function as measured by the Bayley Scales of Infant Development II (BSID-II); (e) oligosaccharide levels in plasma and urine; and (f) respiratory function as measured by number of days spent on ventilation (both invasive and non-invasive) from Baseline to Week 52.

METHODOLOGY

This was a multinational, multicenter open-label study of 18 patients with infantile-onset Pompe disease who received the first dose of Myozyme^® at ≤ 6 months of age. Eligible patients were randomized in a 1:1 ratio to receive intravenous (IV) infusions of Myozyme^® at a dose of 20 mg/kg every other week (qow) or 40 mg/kg qow for the duration of the study. Efficacy, safety, pharmacokinetic and pharmacodynamic evaluations were performed at scheduled visits throughout the study treatment period while adverse events (AEs) and concomitant medications and therapies were continuously monitored. An independent Data Safety Monitoring Board (DSMB) reviewed safety data regularly as outlined in the DSMB Charter. An independent Allergic Reaction Review Board (ARRB) reviewed signs of moderate or severe infusion associated reactions (IARs) and provided guidance on IAR management.

NUMBER OF PATIENTS (PLANNED AND ANALYZED)

Planned: A minimum of 16 patients with infantile-onset Pompe disease were to be treated with Myozyme®.

Actual: Eighteen patients were enrolled and treated with Myozyme® and 17 completed the study.

DIAGNOSIS AND MAIN ELIGIBILITY CRITERIA

Inclusion:

Subjects who met all of the following inclusion criteria were eligible to participate in this study:

The patient’s legal guardian(s) provided written informed consent prior to any study-related procedures being performed;

The patient had documented clinical symptoms of infantile-onset Pompe disease in his or her medical record. In addition, the patient must have: (a) had deficient endogenous GAA activity indicative of Pompe disease AND (b) cardiomyopathy as measured by a study site cardiologist;

The patient must be no older than 26 weeks and 0 days, corrected for gestation if necessary (gestational age of < 40 weeks was adjusted to a full term gestational age of 40 weeks), at the first dose of Myozyme®;

The patient and his/her legal guardian(s) were able to comply with the clinical protocol.

Exclusion:

Subjects who met any of the following exclusion criteria were not eligible for participation in this study:

Symptoms of respiratory insufficiency, including: (a) O2 saturation < 90% on room air as measured by pulse oximetry; or (b) venous partial pressure of carbon dioxide (PCO2) > 55 mmHg on room air or arterial PCO2 > 40 mmHg on room air; or (c) any ventilation use (invasive or noninvasive) at the time of enrollment;

Major congenital abnormality;

Clinically significant organic disease (with the exception of symptoms relating to Pompe disease), including clinically significant cardiovascular, hepatic, pulmonary, neurologic, or renal disease, or other medical condition, serious intercurrent illness, or extenuating circumstance that, in the opinion of the Investigator, precluded participation in the study or potentially decreased survival;

Use of any investigational product within 30 days prior to study enrollment;

Received enzyme replacement therapy (ERT) with GAA from any source.

TEST PRODUCT, DOSE, AND MODE OF ADMINISTRATION

Patients were randomly assigned in a 1:1 ratio to receive IV infusions of Myozyme® at a dose of either 20 mg/kg qow OR 40 mg/kg qow.

DURATION OF TREATMENT

Patients were treated with Myozyme® for a minimum of 52 weeks (ranging from 52 to 106 weeks).

REFERENCE THERAPY, DOSE AND MODE OF ADMINISTRATION

No reference therapy was used in this study.

CRITERIA FOR EVALUATION

Criteria for Evaluation – Efficacy
Primary efficacy was measured as the proportion of patients who were alive and free of invasive ventilator support at 18 months of age (both dose groups combined), as compared to the proportion of patients alive at 18 months of age in a historical cohort.

Secondary efficacy was evaluated as (1) the proportion of patients treated with Myozyme® who were alive and free of invasive ventilator support at 12 months of age; the dose groups were combined and compared to a historical control subgroup; (2) the proportion of patients treated with Myozyme® (both dose groups combined) who were alive and free of any ventilatory support (invasive or non-invasive) at 18 months of age, as compared to the proportion of patients alive at 18 months of age in a historical cohort; (3) changes in LVMI from Baseline to Week 52; and (4) physical growth as measured by changes in length and weight from Baseline to Week 52.

Tertiary efficacy was evaluated as (1) the proportion of patients alive at 18 months of age; (2) the proportion of patients with signs and/or symptoms of cardiac failure; (3) motor development by the AIMS and the number of motor development milestones achieved; (4) cognitive function as determined by the BSID-II; (5) functional status as measured by the PEDI and Pompe PEDI; (6) plasma and urine oligosaccharides; and (7) the number of days spent on any type of ventilation.

Criteria for Evaluation – Safety
Safety was evaluated in terms of AEs, related AEs, serious AEs (SAEs), IARs, routine laboratory measurements (chemistry, hematology, and urinalysis), vital sign parameters, physical examination findings, electrocardiogram (ECG) parameters, hearing testing, and immunogenicity testing.

STATISTICAL METHODS

The following analyses were prospectively defined in the Statistical Analysis Plan.

Statistical Methods – Efficacy
Continuous data were summarized using descriptive statistics (number, mean, median, standard deviation, minimum and maximum). Categorical data were summarized using frequencies and percentages. For the primary efficacy measure, the proportion of patients alive and free of invasive ventilation at the milestone age of 18 months and the corresponding 95% 2-sided confidence interval (CI) were constructed based on a Kaplan-Meier estimate from data on time to death or first ventilator use.

Statistical Methods - Pharmacokinetics and Pharmacodynamics
PK parameters were estimated from plasma rhGAA concentration-time data collected on Day 0 and Week 12 using compartmental methods under a nonlinear mixed effects model paradigm wherein each PK parameter was an allometric power function of weight. Once the best structural model was identified, the influence of dose, age, and sex was examined. When the final PK model was determined, empirical Bayes estimate of each individual’s PK parameters, e.g., clearance (CL), were estimated.

Secondary parameters were calculated based on the primary PK parameters (area under the curve [AUC], half-life [t1/2], and volume of distribution at steady state [Vss]) or from direct observation of the data (Cmax). Repeated measures analysis of variance was then used to determine whether the PK of rhGAA changed over time. The primary PD parameter for evaluation was the difference in skeletal muscle glycogen content between Baseline, Week 12, and Week 52. Results were summarized descriptively. Changes (absolute and percent change) in glycogen content and GAA activity in muscle biopsy samples from Baseline were summarized. The number and proportion of patients with a decrease in glycogen content and those patients with increased tissue GAA activity over time were summarized.

Statistical Methods – Safety
Safety assessments were based on the incidence of AEs. AEs were coded using the Medical Dictionary for Regulatory Activities (MedDRA), and summarized by system organ class (SOC) and preferred term. A detailed listing of patients who experienced AEs and SAEs is presented, along with severity (mild, moderate, or severe). Relationships of the AE to treatment were categorized as not related, remote/unlikely, possible, probable, or definitely related. The incidence of AEs was tabulated by severity and by relationship to treatment. AEs occurring on the day of infusion were separately summarized and listed by patient. All laboratory values were classified as normal, below normal, or above normal based on normal ranges supplied by the laboratory. The analysis of laboratory values was based on frequencies of abnormal values and frequencies of clinically significant abnormal values; these were presented in both tabular form and listed by individual patient. Immunogenicity was evaluated in terms of anti-rhGAA antibody titers and the presence of inhibitory antibody activity.

SUMMARY / CONCLUSIONS

All enrolled patients had a confirmed diagnosis of infantile-onset Pompe disease. One of the 18 treated patients was diagnosed prenatally and confirmed postnatally. The majority of patients in this international population (N=18) were Caucasian. Neither gender predominated, and patients began Myozyme® treatment between the ages of 1.2 and 6.1 months of age (corrected for gestation). The median age at first symptoms was 1.0 month, and the median age at diagnosis was 4.3 months (from date of birth). Three of the patients were CRIM (-) negative. At Baseline, mean GAA activity in skin fibroblasts in all patients was <1%.

Summary / Conclusions – Efficacy
All 18 patients had GAA activity levels < 1% of normal as measured in skin fibroblasts and therefore all patients were included in the primary efficacy analysis. Fifteen of the 18 patients reached the age of 18 months before the end of the study. Two patients were censored from the primary efficacy analysis because they had not reached the age of 18 months at the end of study, although they were free of invasive ventilatory support at this time point. At the 18-month milestone age, 3 patients were receiving invasive ventilatory support. The proportion of Myozyme®-treated patients alive and free of invasive ventilation at the age of 18 months was 83.3% (95% CI: 66.1 – 100). In comparison, only 1 out of 61 untreated patients in the AGLU01602 historical control subgroup remained alive at 18 months of age (without consideration of ventilator support), which corresponds to an estimate of 1.9% survival (95% CI: 0 – 5.5). Therefore, the primary endpoint of invasive ventilator-free survival was met.

Of the 15 patients who reached the age of 18 months before the end of the study, 10 were alive and free of any ventilation (invasive or non-invasive) at the age of 18 months, with a corresponding Kaplan-Meier estimate of 66.7% (95% CI: 44.9 – 88.4). Of the 18 patients treated, 6 patients required either invasive or non-invasive ventilation. Two patients were censored from the any ventilation analysis because they had not reached the age of 18 months at the end of the study, although they were free of any ventilatory support at this time point. Myozyme® treatment markedly extended survival, as 100% of the patients who were not censored from the analysis survived to the age of 18 months, compared to 1.9% survival in the untreated historical control subgroup. Note that the 3 patients who were censored from the survival analysis (at ages 15.9 months, 17.9 months, and 14.4 months) all remained alive at the end of the study.

Cox regression analyses were used as additional sensitivity measures to compare invasive ventilation-free survival, ventilator-free survival, and overall survival in Myozyme®-treated patients versus untreated historical control patients. Myozyme® was found to reduce the risk of death or invasive ventilation by 92% (hazard ratio of 0.08, 95% CI: 0.03, 0.21) and to reduce the risk of death or any type of ventilation by 88% (hazard ratio of 0.12, 95% CI: 0.05, 0.29). In terms of overall survival, Myozyme® treatment significantly reduced the risk of death by 99% (hazard ratio of 0.01, 95% CI: 0.01, 0.10).

Cardiomyopathy parameters were evaluated by echocardiography over the course of the study. LVM Z scores and LVMI were highly elevated in these patients at Baseline, as compared to values in normal pediatric subjects. After 52 weeks of treatment, Myozyme® progressively and dramatically decreased both LVM Z-scores and LVMI, which corresponded to LVM moving towards the normal range in all 14 patients who had data available at both Baseline and Week 52. None of the patients exhibited signs or symptoms of cardiac failure at Week 52. Fifteen of 18 patients (83.3%) maintained or improved weight-for-age percentiles. Fifteen of the 16 patients (93.8%) who had body length measured at Baseline maintained normal body length-for-age percentiles during the 52-week treatment period. Thus, for the majority of patients assessed, treatment with Myozyme® resulted in maintenance of growth and prevention of failure to thrive. In contrast, 53% of untreated patients with infantile-onset Pompe disease exhibited failure to thrive (AGLU-004-00).

Motor development and functional skills were evaluated over the course of the study. During 52 weeks of treatment, the majority of patients demonstrated substantial gains in age-equivalent AIMS scores (13 of 18 or 72.2%) and clinically meaningful improvement in functional status (17 of 18 or 94.4%). Of these 13 patients, 7 learned to walk independently (walkers); 3 were able to pull to stand independently and walk with their hands held (standers); and 3 were able to roll and sit independently, but were unable to bear weight through their legs (functional sitters). The remaining 5 patients exhibited few motor and functional gains over 52-weeks of treatment (minimal motor responders). Untreated Patients with infantile-onset Pompe disease, especially those with the most rapidly progressive form, either never acquire the muscle strength or motor skills necessary to perform these skills, or if they do acquire these skills, they are subsequently lost (AGLU-004-00, Hirschhorn, 2001, The Metabolic and Molecular Basis of Inherited Disease; van den Hout, 2003, Pediatrics).

Cognitive function was assessed using the BSID-II. By Week 52, 9 of the 17 patients who were evaluated at both Baseline and Week 52 had mental development index (MDI) scores within normal limits, 4 patients had MDI scores indicating mildly delayed performance, and 4 patients had an MDI score consistent with significantly delayed performance. These findings indicate that the patients generally continued to acquire cognitive, language, and personal/social development skills during the 52-week Myozyme® treatment period.

Oligosaccharide (Hex4) levels were measured in urine and plasma at various time points during the study, as a possible non-invasive method of monitoring disease state and response to therapy in Pompe patients. Urinary Hex4 levels were elevated in all 16 patients who had measurements at Baseline. Myozyme® treatment decreased urinary Hex4 levels from a median of 33.4 mmol/mol creatinine (Cr) at Baseline to 17.9 mmol/mol Cr by Week 52, with changes beginning as early as Week 4. Within individual patients, urinary Hex4 values decreased in 10 of 15 patients who had measurements at both Baseline and Week 52. In general, patients who exhibited motor gains over 52-weeks of treatment had lower urinary Hex4 levels than patients who did not make motor gains.

GAA activity and glycogen content (measured biochemically and histomorphometrically) were assessed in skeletal muscle biopsies taken at Baseline, Week 12, and Week 52. At Baseline, all 18 patients had very low skeletal muscle GAA activity (≤ 8.8 nmol/hr/g). All patients who underwent biopsies at both time points exhibited a marked increase in GAA activity from a median value of 0.0 nmol/hr/g at Baseline to 104.1 nmol/hr/g at Week 52. Thirteen of 16 patients had stable or decreased muscle glycogen content by both biochemical and histomorphometric methods of analysis. Of these 13 patients, 11 (84.6%) experienced motor gains as assessed by AIMS scores. Overall, patients with lower glycogen levels at Baseline generally performed better in motor assessments.

The PK characteristics of Myozyme® in patients in Study AGLU01602 were comparable on Day 0 and after 12 weeks of treatment. Mean values for CL, Vss, and t½ across all sample time points were approximately 22 mL/hr/kg, 67 mL/kg, and 2.8 hr, respectively. The PK profile of Myozyme® did not change in response to repeated exposures and the presence of anti-rhGAA antibodies did not appear to affect rhGAA PK.

A similar proportion of patients assigned to the 20 mg/kg and 40 mg/kg dose groups successfully met clinical endpoints such as ventilation-free survival, survival, LVMI, growth, motor development, and functional status.

Summary / Conclusions – Safety Results
Treatment with myozyme® was generally well tolerated at the 2 doses used in this study. A total of 1150 treatment-emergent aes were experienced by the 18 patients. Of these, 480 (41.7%) were experienced by the 9 patients in the 20 mg/kg dose group and 670 (58.3%) were experienced by the 9 patients in the 40 mg/kg dose group. One hundred seventy (14.8%) of the 1150 treatment-emergent aes were assessed as being possibly, probably, or definitely related to treatment and 164 of these were assessed as jars.

Similar numbers of severe AEs were observed in the 2 dose groups. Twenty-nine (46.8%) of the 62 severe AEs occurred in 5 of 9 patients in the 20 mg/kg dose group and 33 (53.2%) occurred in 7 of 9 patients in the 40 mg/kg dose group. None of the severe AEs were assessed as being related to treatment. Most of the AEs experienced by patients in this study were related to the underlying manifestations of infantile-onset Pompe disease. The majority of AEs were classified in the SOCs of Infections and Infestations; Respiratory, Thoracic, and Mediastinal Disorders; and General Disorders and Administration Site Conditions. The most frequently reported AEs, by MedDRA preferred term, were pyrexia, cough, vomiting, and decreased oxygen saturation.

One patient died at the age of 19.8 months (Study Week 61), due to desaturation and bradycardia while hospitalized for treatment of respiratory distress and pneumonia. The death was assessed by the Investigator as unrelated to Myozyme® treatment. No patients withdrew from treatment during the study. Seventeen of the 18 patients (94%) experienced a total of 174 SAEs during the study.

Similar numbers of SAEs occurred in the 2 dose groups (88 SAEs in 8 patients in the 20 mg/kg dose group and 86 SAEs in 9 patients in the 40 mg/kg dose group). The majority of the SAEs were mild or moderate in intensity (127 events, 73.0%) and 47 SAEs (27.0%) were severe; none of the severe SAEs were assessed as related to Myozyme® treatment. One hundred seventy-one of the 174 SAEs (98.3%) were considered unrelated (i.e., not related or unlikely/remotely related) to treatment with Myozyme®.

The majority of SAEs were classified in the SOCs Respiratory, Thoracic, and Mediastinal Disorders and Infections and Infestations. The most frequent SAEs, by MedDRA preferred term, were pneumonia, respiratory failure, pneumonia aspiration, bronchopneumonia, and catheter-related infections.

A total of 164 IARs occurred in 11 patients in this study. Forty-one IARs were experienced by 5 patients in the 20 mg/kg dose group and 123 IARs were experienced by 6 patients in the 40 mg/kg dose group. Most of the IARs were experienced by 3 patients. Two of these patients were assigned to the 40 mg/kg dose group.

IARs were generally well tolerated, and were managed with a rate reduction and/or an interruption of the Myozyme® infusion. In all instances, patients recovered from the IAR(s) without sequelae and infusions were completed after the interruption. All of the IARs were assessed as mild or moderate in intensity. Three IARs were assessed as serious (2 episodes of moderate urticaria and 1 episode of moderate rales in one patient).

Sixteen of the 18 patients developed IgG antibodies to Myozyme® during the study. One patient was seropositive at Baseline, which suggests pre-existing cross-reactivity, and 2 patients remained seronegative at all time points tested. There was a tendency for the patients with the highest antibody titer levels and patients in the 40 mg/kg dose group to experience more IARs than the patients with lower antibody titer levels and patients in the 20 mg/kg dose group. One of the 18 patients showed inhibitory antibody activity at Weeks 52 and 64 (the last time point tested in the study for this patient). None of the other patients exhibited any inhibitory antibody activity at any time point in the study.

Changes in laboratory parameters observed during the analysis period were generally consistent with the evolving clinical status of individual patients. Hearing was evaluated by oto-acoustic emission (OAE) in 13 of 18 patients at Baseline. Six of the 13 patients who had OAE tests at Baseline had abnormal hearing in at least 1 ear and 4 of 5 patients who had brainstem-auditory evoked response (BAER) testing at Baseline had abnormal hearing. Abnormal bilateral hearing was found in 3 of 3 patients who had OAE tests at Week 52 and in 5 of 6 patients who had BAER tests at Week 52. The types of hearing loss observed at Week 52 included severe hypoacousia, moderate to severe mixed hearing loss, and mild conductive hearing loss. Interpretation of hearing test results was complicated by the presence of fluid in the middle ear in some patients. Hearing loss has been commonly observed in patients with glycogen storage disorders, including Pompe disease (Galton, 1976, Acta Paediatr Scand; Jurecka, 1985, Arch Dermatol.; Kamphoven, 2004, Neurobiology of Dis). Moreover, a study in a knockout mouse model of Pompe disease revealed that this most likely is caused by cochlear pathology due to glycogen accumulation (Kamphoven, 2004, Neurobiology of Dis). These findings strongly suggest that the hearing loss in patients with Pompe disease is related to the disease itself and is not a complication of therapy.

Disease-Related Complications: Pompe disease is associated with multiple serious complications, including respiratory, cardiac, and muscle difficulties, as well as increased susceptibility to fractures. Patients with Pompe disease have an increased risk of respiratory distress, cardiac complications and death from general anesthesia, due to severe myocardial hypertrophy and respiratory muscle weakness (Ing, 2004, Pediatr Anaesth). In previous studies of ERT in patients with Pompe disease, events of arrhythmia during induction of anesthesia have been reported, some with fatal outcome. Four patients in Study AGLU01602 experienced an SAE of cardiac arrhythmia following anesthesia. Two of these events occurred when two patients were anesthetized during the Baseline period, 1 event occurred when 1 patient was anesthetized during the study (at Week 89), and 1 occurred 6 days after another patient completed the study. All patients recovered from these events without sequelae and none of the events were assessed as related to Myozyme® administration. A total of 5 fractures were experienced by 2 of the 18 patients in this study (11%); these events were designated as SAEs. Pompe disease is associated with decreased bone density (osteopenia) and fractures have been observed in other studies of infantile onset Pompe disease (Krishnamurthy, 2005, Mol Genet Metab). The fractures were assessed as unrelated to Myozyme® treatment.

CONCLUSION

The data from this study demonstrate that Myozyme® therapy is a safe and effective treatment for infantile-onset Pompe disease. Myozyme® treatment prolonged ventilator-free survival in patients with infantile-onset Pompe disease as compared to an untreated historical control population. The relatively young age at which these patients initiated Myozyme® treatment (≤ 6 months of age) may have helped to prevent or delay the onset of the most severe symptoms of Pompe disease in this cohort.