Protocol AGAL-008-00: Multi-center, Randomized, Double-Blind, Placebo-Controlled Study of the Safety and Efficacy of Recombinant Human α-Galactosidase A (r-hαGAL) on Progression of Renal Disease and Significant Clinical Events in Patients with Fabry Disease

Fabrazyme^® (agalsidase beta)

Drug Name	Generic Name	Studied Indications or Disease	Approved U.S. Drug Label
Fabrazyme®	agalsidase beta	Fabry disease	Prescribing Info

NAME OF SPONSOR/COMPANY

Genzyme LLC, 500 Kendall Street, Cambridge, Massachusetts, 02142

Investigators and Study Center(s)

Forty-one study centers in North America and Europe were approved to participate in this clinical trial, and patients at 23 study centers were eligible to be enrolled. During the study, 12 patients transferred from their enrolling center to another approved study center, and by the end of the study, patients had been treated by investigators at 26 study centers.

Publication (Reference)

Publications

Studied Period

20 February 2001 (first patient enrolled) to
30 January 2004 (last patient completed)

Phase of Development

Phase 4

Objectives

The primary objective was to assess the effectiveness of r-hαGAL (Fabrazyme^®), as compared to placebo, in the time to clinically significant progression of the composite outcomes of renal disease, cardiac disease, cerebrovascular disease, and/or death among Fabry patients with advanced Fabry disease.

Methodology

This was a multicenter, multinational, randomized, double-blind, placebo-controlled trial. Patients were assigned to treatment using a 2:1 (Fabrazyme:placebo) randomization scheme that sought to achieve a 2:1 balance between the Fabrazyme group and placebo group, respectively, at each site.

Throughout the study, patients continued to receive the standard of care, and were monitored closely for disease progression. If a patient experienced a clinically significant event that, in the opinion of the Principal Investigator (PI), met the criteria of a primary endpoint, the event was then reviewed by a blinded Independent Adjudication Board (IAB). If the event was confirmed as meeting the primary endpoint, the PI, in discussion with the Medical Monitor, had the option to enter the patient into open-label treatment.

Patients who were entered into open-label treatment followed the same schedule of events as the patients receiving double-blind treatment.

Patients who met specific criteria had the option to receive infusions of Fabrazyme at home, and returned to their original treating physician every 3 months for study evaluations.

Number of Patients (Planned and Analyzed)

PLANNED: Approximately 80 patients

RANDOMIZED AND ANALYZED: 82 patients were randomized (51 to Fabrazyme and 31 to placebo), and 82 patients were analyzed (Intent-to-Treat population). The Per-Protocol (PP) population included 74 patients, 47 in the Fabrazyme group and 27 in the placebo group (8 patients, 4 in the Fabrazyme group and 4 in the placebo group, were excluded due to major protocol violations, which were identified prior to unblinding the data). Ten female patients were enrolled in the study (4 were randomized to placebo and 6 to Fabrazyme).

Diagnosis and Main Criteria for Inclusion

Based on the final protocol amendment, patients who met all of the following inclusion criteria were eligible to participate in the study:

The patient had to have signed informed consent. All male and female patients had to be aged ≥ 16 years and have a current diagnosis of Fabry disease with no prior enzyme replacement therapy (ERT) for treatment of Fabry disease. The patient had to have documented plasma α-galactosidase A (αGAL) activity of < 1.5 nmol/hr/mL or a documented leukocyte αGAL activity of < 4 nmol/hr/mg. Patients must have had a clinical presentation consistent with Fabry disease (e.g., angiokeratoma, Fabry pain, decreased sweating, corneal opacities, etc.). Patients must have had one or more of the following: two consecutive serum creatinine measurements > 1.2 and < 3 mg/dL (106.1 to 265.2 µmol/L) AND the two values within 15% of each other when the higher value is used as the reference OR if the patient’s serum creatinine measurement is < 1.2 mg/dL, then estimated creatinine clearance < 80 mL/min (using the Cockroft-Gault formula and the average of the two values) AND, the two values are within 15% of each other when the higher value is used as the reference. Patients had to be able to comply with the clinical protocol. Female patients of childbearing potential had to have a negative pregnancy test (urine β-hCG). In addition, all female patients were required to use a medically accepted method of contraception throughout the study. Patients were not eligible for participation if they had undergone or were scheduled for kidney transplantation, were on dialysis, had participated in an investigational drug study within 30 days of the start of their participation in this study, or if the patient had one of the following: acute renal failure, unconfirmed Fabry disease, diabetes mellitus or presence of confounding renal disease, a serum creatinine of < 1.2 mg/dL (< 106.1 Vmol/L) unless estimated creatinine clearance was < 80 mL/min, a history of transient ischemic attack (TIA) or ischemic stroke within 3 months of study entry documented by a neurological deficit, current critical coronary artery disease (as documented by a presently unstable angina and/or documented myocardial infarction within 3 months), congestive heart failure (contributed by Fabry disease) as defined by Class III or Class IV cardiac status as evaluated under the New York Heart Association classification, severe residual neurological deficit that would confound the detection of new events as determined by an attending neurologist and/or PI, a clinically significant organic disease or an unstable condition that, in the opinion of the Investigator, would preclude participation in the study, were unwilling to comply with the requirements of the protocol, or had a medical condition, serious intercurrent illness, or extenuating circumstance that would significantly decrease study compliance.

Test Product, Dose, and Mode of Administration

Fabrazyme was supplied in 20 mL vials (35 mg/vial) as a lyophilized preparation. Each vial of Fabrazyme was reconstituted with 7.2 mL of Sterile Water for Injection. The appropriate amount of reconstituted Fabrazyme was further diluted with a 0.9% sodium chloride solution to a final total volume of 500 mL.

Patients randomized to Fabrazyme received approximately 1 mg/kg (0.9 to 1.1 mg/kg) of Fabrazyme intravenously (IV) every 2 weeks for the duration of the study.

Initially, patients received an IV infusion at a rate of no more than 0.25 mg/min (15 mg/hr) over approximately 4 to 6 hours for the first 8 infusions. After the eighth infusion, the infusion rate could be increased, as tolerated; however, the total infusion time could not be less than approximately 90 minutes.

Once a patient entered into open-label treatment, the patient could be infused according to a ramp infusion scheme. The ramp infusion began at a rate of 0.1 mg/kg/hr and was gradually increased by 0.2 mg/kg/hr every 15 minutes (if there was no sign of a reaction) until the maximum rate of 0.7 mg/kg/hr was reached. For patients who were already receiving open-label treatment, the investigator could have continued the current infusion regimen or switched the patient to the ramp infusion scheme.

Duration of Treatment

Up to approximately 35 months (approximately 76 infusions). The median time from first infusion to Final Blinded Visit was 18.5 months (range 0.0-35.1 months).

Reference Therapy, Dose and Mode of Administration

Patients randomized to Placebo received placebo intravenously (IV) every 2 weeks for the duration of the study.

Placebo was a lyophilized preparation of mannitol with a phosphate buffer in vials identical to those containing Fabrazyme. Placebo vials were reconstituted with 7.2 mL of Sterile Water for Injection and further diluted with a 0.9% sodium chloride solution to a final total volume of 500 mL

Criteria for Evaluation:

EFFICACY: The primary efficacy endpoint was the time to the first occurrence of a clinically significant renal (33% increase in serum creatinine, dialysis or transplant), cardiac (myocardial infarction, significant change in cardiac status, i.e., angina, congestive heart failure or symptomatic arrhythmia requiring medication or surgery) or cerebrovascular (stroke or transient ischemic attack) event and/or death (due to any cause) in Fabrazyme patients as compared to placebo patients.

The secondary endpoints evaluated in the study were the time to first renal event, slope of estimated glomerular filtration rate (GFR), slope of inverse serum creatinine values, and neuropathic pain as assessed by Question 12 of the Brief Pain Inventory (BPI) Questionnaire (pain at its worst).

SAFETY: Safety was measured in terms of physical (including medical/surgical history), vital sign parameters, electrocardiogram (ECG) parameters, echocardiograms, number and duration of infusions, MRI/neurological examination, laboratory safety parameters, antibody formation to Fabrazyme, adverse events (AEs), related adverse events that occurred on the same day as an infusion, serious adverse events (SAEs), death, and concomitant medication use.

Statistical Methods
EFFICACY: Efficacy analyses were performed on all randomized patients, defined as the Intent-to-Treat population (ITT), as well as a Per-Protocol (PP) population. The PP population was prospectively defined prior to database lock. Any patient missing 20% or more of the infusions, or had major protocol violations, was excluded from the PP population. The primary endpoint analysis on the time to first clinical event, as planned in the protocol, was a 2-tailed log-rank test on the ITT population at the α=0.05 significance level. The primary efficacy endpoint was summarized in the form of a Kaplan-Meier survival curve that displays the rate of primary endpoint events over time in each of the treatment two groups.

The study protocol also stated that baseline imbalances in important prognostic covariates would be adjusted for using a Cox Proportional Hazards Model. Proteinuria was one such covariate that was not equally distributed between the two treatment groups at baseline. In addition, proteinuria was found to be the most important prognostic indicator relative to both the clinical event endpoint and the renal event endpoint. Therefore, a Cox Proportional Hazards Model was performed for the primary endpoint adjusting for baseline proteinuria by adding it as a covariate to the model. This was done for both the ITT and PP populations. Also, to review consistency of treatment effect across each component of the primary endpoint, the number and percentage of each component event (renal, cardiovascular, cerebrovascular, and death) was summarized by treatment group. Hazard ratios and 95% Confidence Intervals were presented for the composite endpoint and renal events. Due to the small number of events, odds ratios and confidence limits were presented for cardiovascular and cerebrovascular events. Time to event analyses were used for the composite endpoint and renal events. Additionally, hazard ratios were calculated for the primary endpoint stratified by baseline serum creatinine and median estimated GFR adjusted for imbalance in proteinuria.

These classical analyses were also interpreted using a Bayesian framework. Assuming a non-informative prior distribution on treatment effect (i.e., assuming we have no prior information on the treatment effect expected in this study), there is greater than a 91% posterior probability that Fabrazyme is beneficial with respect to the prevention of events based on the data observed in this study. More precise analyses (adjusting for baseline proteinuria imbalance) suggest that this posterior probability is likely to be closer to 98%.

The PP population analyses were conducted on the primary endpoint as well as the secondary endpoint defined as time to first renal event. For both time to first renal event and time to first clinical event (unadjusted for baseline proteinuria), differences between the treatment groups were assessed by means of a two-tailed log-rank test. Kaplan-Meier curves and other relevant summary statistics for each treatment group were also presented. For time to first clinical event, adjusted for baseline proteinuria, a Cox Proportional Hazards Model was used to assess treatment effect.

Secondary endpoints were analyzed using the ITT population. The secondary endpoints were time to first renal event, patient’s GFR slope over time, patient’s inverse serum creatinine slope over time, and neuropathic pain as assessed by question 12 of the Brief Pain Inventory questionnaire. The three secondary renal endpoints were analyzed with and without adjusting for baseline proteinuria. The time to first renal event was compared between the treatment groups using a 2-sided log-rank test. Kaplan-Meier curves, the hazard ratio (risk ratio) for comparing the treatment groups with corresponding confidence intervals, and relevant summary statistics are described.

Linear trend patient slopes for longitudinal estimated GFR were estimated by means of a linear mixed model. Between treatment group differences in slopes were compared using a Wilcoxon rank sum test. These slopes were based on data values from infusion 1 onward to the Final Blinded Visit defined as the first occurrence of an event, open label therapy or exit date. Treatment group differences were also analyzed stratified on patients with baseline GFR value ≤ 60 mL/min/1.73 m² (at least Stage 3 Chronic Kidney Disease) and > 60 mL/min/1.73 m² (Stage 1 or 2 Chronic Kidney Disease) (KDOQI, 2002, Am J Kidney Dis). Similarly, inverse serum creatinine linear slopes were estimated for all patients, testing for overall treatment group differences and stratified by the median baseline serum creatinine (1.5 mg/dL).

For neuropathic pain, a change score was derived from Baseline to each subsequent 6 month time period separately and then from Baseline to Final Blinded Visit. Differences in estimated neuropathic pain distribution from Baseline to 1 year and to 2 years between the treatment groups were assessed using a Wilcoxon rank sum test.

SAFETY: The safety analyses were performed on the Intent-to-Treat population. For patients who initially received placebo and then switched to open-label Fabrazyme, the safety observations that were collected while on placebo are summarized under the placebo arm, and observations from the start of treatment with Fabrazyme are summarized as a third treatment arm (placebo/Fabrazyme). Adverse Events and Concomitant Medications are summarized by the treatment that the patient received when having the event or taking the medication. In addition, tables are summarized by the treatment groups that the patients were randomized to, showing the events or medication that occurred pre- and post-transitioning to Fabrazyme. Tables are stratified by the duration of time on study (0-6 months, 0-12 months, 0-24 months, and entire duration of study). In addition, AEs were stratified by 0-6, 6-12, and 12-24 months post-Baseline. For patients who were randomized to placebo, tables are stratified by duration of exposure to Fabrazyme (post transition) using the same intervals.

AEs were coded using the WHOART dictionary, and the frequency and percentage of patients who had an AE (as well as infusion-associated AEs and SAEs) are presented stratified by severity, by relationship to treatment, and by whether the patient seroconverted or not. A detailed listing of patients who experienced AEs and serious adverse events (SAEs) is presented.

Laboratory evaluations, vital signs, 12-lead ECGs, echocardiograms, and MRIs were summarized for each treatment arm at each time point. Additionally, the changes from Screening (or pre-infusion at Visit 1 (Day 0)) and every 6 months thereafter were summarized. Frequency and percentage of seroconverted (IgG) patients and time to seroconversion, as well as antibody titers for IgG positive patients who seroconverted, are presented. Physical examination results are summarized every 6 months. Also, the number of patients who received treatment (infusion) and summary statistics for duration of infusion are presented at each visit. National Institutes of Health (NIH) stroke scale results and death defined by an AE (based on AE page of the CRF) are also listed. Neurological examination results were summarized as normal or abnormal in 6 month intervals. Concomitant medications are summarized by the class of medication, medication, and the number of patients with at least one administration of medication. Concomitant pain medications are summarized as opioid analgesics, non-opioid analgesics, other pain medications, and antiepileptics. ACE Inhibitors and Angiotensin Converting Enzyme Receptor Blockers (ARBs) are identified separately.

Summary – Conclusions
Efficacy Results

There was a strong trend favoring Fabrazyme in the ITT population (Hazard Ratio=0.57, CI=0.27, 1.22; p=0.1449) in the reduction of the occurrence of the primary endpoint (progression of renal, cardiac or cerebrovascular disease or death). The favorable and consistent trend was noted across the renal, cardiac and cerebrovascular components of the primary endpoint. There was a 46% risk reduction in the PP population (Hazard Ratio 0.54; 95% confidence interval 0.25, 1.19, p=0.1229).

Baseline proteinuria strongly predicted both the primary outcome and the occurrence of primary endpoint renal events. Further, there was an imbalance between groups for Baseline proteinuria: a higher proportion of patients randomized to Fabrazyme had higher Baseline proteinuria levels as compared to the placebo group. Since there was an imbalance in Baseline proteinuria between the two groups and proteinuria was the strongest predictor of the occurrence of the primary endpoint, correction for proteinuria using a Cox Proportional Hazards Model was included in the analyses of the primary endpoint (Piantadosi S. Clinical Trials: A Methodologic Perspective. Wiley: New York. 1997. Chapter 13 pg. 353-354). After using an appropriate adjustment for the imbalance in Baseline proteinuria in this relatively small study, a pronounced treatment effect was observed, which approached statistical significance for the Intent-to-Treat population: Risk Reduction 53% (p=0.0577). The treatment effect achieved statistical significance with a 61% reduction in the risk of meeting the primary endpoint (p=0.0341) for the PP population. The trend favoring Fabrazyme was seen even after stratifying patients on Baseline renal function, with the greatest benefit seen among patients with less severe renal disease at Baseline.

The beneficial effect of Fabrazyme was supported by several secondary and tertiary endpoints. The results of the secondary endpoint analyses suggest that the greatest benefit in preservation of renal function appears to be among patients who have less severe renal disease at Baseline. There was a statistically significant effect on the change in slope of estimated GFR in patients treated with Fabrazyme compared to placebo patients among patients with Baseline estimated GFR values > 60 mL/min/1.73 m² (Stage 2 Chronic Kidney disease or better). Similar results were obtained when the slope of inverse of serum creatinine was examined.

Neuropathic pain at its worst was low throughout the study, and in fact only 46% of patients had pain at Baseline. There was a reduction in the pain scores (pain at its worst) at the end of 2 years as well as at the Final Blinded Visit among patients treated with Fabrazyme who had pain at Baseline. This result was not statistically significant but the trend is encouraging. It is important to note that the current study was not designed as a pain trial, patients were not selected on the basis of pain and the number of patients with pain was low. Further, patients had access to rescue pain medications.

Safety Results

Fabrazyme when compared to placebo could be safely administered to patients with mild to moderate renal disease at a dose of 1.0 mg/kg every two weeks. No new safety concerns were identified during this study.

Three deaths (one placebo patient and two Fabrazyme patients) were reported during this trial, none of which were considered to be related to treatment. Two patients died secondary to cardiac arrest while one patient died after developing multiple bilateral pulmonary emboli. All patients had medical histories significant for ischemic heart disease, coronary artery disease, cerebrovascular accident and valvular regurgitation.

Thirty patients experienced a total of 56 SAEs, the majority of which were not related to treatment as assessed by the reporting physicians. Three patients experienced SAEs that were considered related to treatment. One patient developed severe hypotension during an infusion and subsequently tested IgE positive. Two other patients had a positive skin test. Two of these three patients were successfully rechallenged, while the third patient had a similar reaction after rechallenge with Fabrazyme.
There were no reports of anaphylaxis.

The majority of all reported adverse events were mild or moderate in intensity. Rhinitis was the most frequently observed AE experienced by patients in the placebo (42%) and Fabrazyme (57%) groups. Other frequently occurring adverse events in the placebo group without regard to causality were coughing and nausea (35%); fever and pharyngitis (29%); vomiting (26%); and headache, upper respiratory tract infection, diarrhoea, and Fabry pain (23%). Other frequently occurring adverse events in the Fabrazyme group without regard to causality were coughing (49%); headache and upper respiratory tract infection (43%); rigors (39%); fever (37%); back pain (35%); fatigue (33%); vomiting (29%); diarrhoea, myalgia, pain, and abdominal pain (27%); Fabry pain and pharyngitis (25%); dizziness (24%); and nausea, oedema dependent, and anaemia (20%).

Among the 12 patients who transitioned from placebo to Fabrazyme, the most frequently occurring adverse events without regard to causality observed while the patients were on Fabrazyme were oedema dependent (33%); upper respiratory tract infection, abdominal pain, hypertension, and fibrillation atrial (25%); and rhinitis, coughing, headache, myalgia, pain, Fabry pain, skin disorder, arthralgia, purpura, and hypotension (17%).

The majority of the related AEs were infusion-associated reactions. The incidence of infusion-associated reactions was higher in the Fabrazyme group compared to the placebo group. The most frequently reported infusion-associated reactions (IARs) in the Fabrazyme group (those occurring in ≥ 2 patients) included rigors, fever, hypertension, vomiting, temperature changed sensation, chest pain, pain, flushing, nausea, tremor (3 reports of shaking and one report of generalized tremor), pruritus, tachycardia, urticaria, Fabry pain, hypoaesthesia, paraesthesia, bronchospasm, abdominal pain, fatigue, and headache. All other IARs for this treatment group only occurred in single patients. The majority of IARs occurred within the first 6 months of treatment and were considered mild or moderate in intensity. The number of IARs decreased over time. The infusion-associated reaction profile was similar to that seen in prior clinical trials with Fabrazyme.

Forty-three of the 63 (68%) patients who received Fabrazyme at any time during the study seroconverted (includes placebo patients who transitioned to Fabrazyme). Four patients tolerized. The majority of patients had seroconverted by the three month timepoint (the first timepoint seroconversion was assessed). Among the 8 female patients who received Fabrazyme during the study, 5 were non-responders (seronegative) and 3 tolerized. Seroconversion did not impact efficacy. The mean time to seroconversion for females was 141 days as compared to 84 days for males. Similarly, the mean time to seroconversion for patients who transitioned to open-label Fabrazyme (n=7 males) was 82 days. Apart from the rate of seroconversion, there is no indication that the clinical response of Fabrazyme is different between males and females.

Over the course of the study, 39/51 (76%) patients in the Fabrazyme group had at least 1 complete infusion (≥ 450 mL) of Fabrazyme with an infusion time ≤ 2.5 hours, and 31/51 (61%) patients had at least 1 complete infusion in ≤ 2 hours. Among the patients who received only placebo (i.e., did not transition to Fabrazyme), 26/31 (84%) patients had at least 1 complete infusion with an infusion time ≤ 2.5 hours, and 18/31 (58%) patients had at least 1 complete infusion in ≤ 2 hours. Among the 12 patients who transitioned from placebo to Fabrazyme, 7 (58%) patients had at least 1 complete infusion of Fabrazyme with an infusion time ≤ 2.5 hours and in ≤ 2 hours.

Infusion times decreased over the duration of the study across all treatment groups. By the final visit, the mean duration for patients in the placebo and Fabrazyme treatment groups was almost half the administration duration as observed during the first infusion. One patient received Fabrazyme infusions safely at home.

No direct toxic effects were demonstrated by laboratory findings, vital signs, echocardiograms, or neurological exams/magnetic resonance imaging scans. There is no evidence to suggest that Fabrazyme induces any clinically significant QTc prolongation. The risk-benefit profile of Fabrazyme remains favorable.

Conclusion:

In conclusion, this trial shows a strong trend indicating the ability of Fabrazyme therapy to slow the rate of clinical progression in renal, cardiac and cerebrovascular outcomes, especially when treatment is initiated at an earlier stage in the course of the disease. No new safety concerns were identified during this study. Fabrazyme can safely be intravenously administered at a dose of 1.0 mg/kg every two weeks.