PI: Intravenous Administration
Intravenous use of GAMMAGARD LIQUID is supported by a study in subjects (N=61) who were treated with 300 to 600 milligram/kg every 21 to 28 days for 12 months. The age range of subjects was 6 to 72 years, with 54% female and 46% male, and 93% Caucasian, 5% African-American, and 2% Asian. Three subjects were excluded from the per-protocol analysis due to non-study product related reasons. The annualized rate of prespecified acute serious bacterial infections, i.e., the mean number of prespecified acute serious bacterial infections per subject per year, was studied (see Table 11).
Table 11 Summary of Validated Acute Serious Bacterial Infections for the Per-Protocol Analysis | Number of Events |
Validated Infections Serious acute bacterial infections were defined by FDA and met specific diagnostic requirements | |
Bacteremia / Sepsis | 0 |
Bacterial Meningitis | 0 |
Osteomyelitis / Septic Arthritis | 0 |
Bacterial Pneumonia | 0 |
Visceral Abscess | 0 |
Total | 0 |
Hospitalizations Secondary to Infection | 0 |
Mean Number of Validated Infections per Subject per Year | 0 |
p-value The rate of validated infections was compared with a rate of 1 per subject per year, in accordance with recommendations by the FDA Blood Products Advisory Committee | p < 0.0001 |
95% Confidence Interval | (0.000, 0.064) |
The annualized rate of other prespecified validated bacterial infections (see Table 12), and the number of hospitalizations secondary to all validated infectious complications also were studied (see Table 11 and Table 12).
Table 12 Summary of Validated Other Bacterial Infections | Number of Events |
Validated Infections Other bacterial infections that met specific diagnostic requirements | |
Urinary Tract Infection | 1 |
Gastroenteritis | 1 |
Lower Respiratory Tract Infection: Tracheobronchitis, Bronchiolitis (Without Evidence of Pneumonia) | 0 |
Lower Respiratory Tract Infection: Other Infections (e.g., Lung Abscess, Empyema) | 0 |
Otitis Media | 2 |
Total | 4 |
Hospitalizations Secondary to Infection | 0 |
Mean Number of Validated Infections per Subject per Year | 0.07 |
95% Confidence Interval | (0.018, 0.168) |
None of the 61 treated subjects was positive for HCV, HIV-1, and HIV-2 and HBV prior to study entry and none converted from negative to positive during the 12-month period.
PI: Subcutaneous (SC) Administration
A prospective, open-label, non-controlled, multi-center study was conducted in the U.S. to determine the efficacy, tolerability and PK of GAMMAGARD LIQUID subcutaneous infusion in adult and pediatric subjects (N=49) with PI. All subjects were treated for 12 weeks with GAMMAGARD LIQUID intravenous infusion every 3 or 4 weeks. Subjects who were on intravenous treatment prior to entering the study were switched to GAMMAGARD LIQUID at the same dose and frequency. Subjects who were receiving subcutaneous immune globulin were switched to GAMMAGARD LIQUID at the intravenous dose they had received prior to switching to subcutaneous treatment. A PK analysis was performed at the end of the intravenous period in all subjects aged 12 years and older.
One week after the last intravenous infusion, each subject began subcutaneous treatment with GAMMAGARD LIQUID at 130% of the weekly equivalent of the intravenous dose for a minimum of 12 weeks. PK data from the first 15 adult subjects were used to determine the dose required to ensure that the IgG exposure with subcutaneous treatment was not inferior to that with intravenous treatment. The median dose determined from these subjects was 137% of the intravenous dose, and subsequently all subjects were treated for a minimum of 6 weeks at this dose. After 6 subcutaneous infusions, a trough IgG level was obtained and used to individually adapt the subcutaneous dose of GAMMAGARD LIQUID to compensate for individual variation from the mean value of 137%. [See Pharmacokinetics (12.3) and Dosage and Administration (2.1)]
All subjects received a minimum of 12 infusions at this individually adapted dose and continued to receive subcutaneous treatment with GAMMAGARD LIQUID until the last subject completed the study. Subjects (N=47) were treated with 2,294 subcutaneous infusions of GAMMAGARD LIQUID: 4 subjects treated for up to 29 weeks, 17 subjects for 30 to 52 weeks, and 26 subjects for 53 weeks or longer. Two subjects that completed the intravenous treatment part of the study did not continue to the subcutaneous treatment part of the study. The median duration of subcutaneous treatment was 379 days (range: 57 to 477 days).
Efficacy was determined throughout the entire subcutaneous phase. There were 31 adults aged 16 years or older, 4 adolescents aged 12 to <16 years, and 14 children aged 2 to <12 years. The volume of GAMMAGARD LIQUID infused was 30 mL per site for subjects weighing 40 kg and greater, and 20 mL per site for those weighing less than 40 kg. The total weekly dose was divided by those values to determine the number of sites.
Mean weekly subcutaneous doses ranged from 181.9 milligram/kg to 190.7 milligram/kg (at 130% to 137% of the intravenous dose). In the study, the number of infusion sites per infusion was dependent on the dose of IgG and ranged from 2 to 10. In 75% of infusions, the number of infusion sites was 5 or fewer.
There were 3 serious validated bacterial infections, all bacterial pneumonia. None of these subjects required hospitalization to treat their infection. The annual rate of acute serious bacterial infections while on GAMMAGARD LIQUID subcutaneous treatment was 0.067, with an upper 99% confidence limit of 0.133, which is lower than the minimal goal of achieving a rate of <1 bacterial infection per patient-year.
Table 13 presents a summary of infections and associated events for subjects during subcutaneous treatment with GAMMAGARD LIQUID. The annual rate of any infection in this study during subcutaneous treatment, including viral and fungal infections, was 4.1 infections per subject per year.
Table 13 Summary of Infections and Associated EventsNumber of subjects (efficacy phase) Total number of subject years Annual rate of any infections | 47 44 4.1 (95% CI 3.2 to 5.1) infections/subject year |
Antibiotic use Included systemic and topical antibacterial, anti-fungal, anti-viral, and anti-protozoal antimicrobials (prophylaxis or treatment)Number of subjects (%) Annual rate | 40 (85.1%) 50.2 (95% CI 33.4 to 71.9) days/subject year |
Days out of work/school/day care or unable to perform normal activities Number of subjects (%) Annual rate | 25 (53.2%) 4.0 (95% CI 2.5 to 6.1) days/subject year |
Hospitalizations due to infections Number of subjects (%) Annual rate | 0 (0.0%) 0.0 (95% CI 0.0 to 0.1) days/subject year |
MMN:
A randomized, double-blind, placebo controlled, cross-over withdrawal study was conducted to evaluate the efficacy and safety/tolerability of GAMMAGARD LIQUID in adult subjects (N=44) with MMN.12 The study examined grip strength in the more affected hand11(measured with dynamometer), and Guy's Neurological Disability Scale (GNDS) [upper limb part 6 subsection].13 Study subjects were on a regimen of licensed immunoglobulin (existing maintenance dose ranging from 0.5 to 2.0 grams/kg/month) prior to enrollment and thus, the results cannot be generalized to naïve patients.
The study comprised of five study periods, each lasting 12 weeks: 3 stabilization phases, one randomized withdrawal phase and one cross-over phase. Open-label GAMMAGARD LIQUID was administered at the beginning (study period 1) and at the end of the study (study period 5) for clinical stabilization, and between the double-blinded periods to prevent carry-over effect (study period 3). If, during either of the double-blinded treatment periods, the subject's upper limb function involving the affected muscles deteriorated such that the subject had difficulty completing daily activities or experienced a decline in grip strength of ≥50% in the more affected hand, the subject was switched directly to the next stabilization phase of open-label GAMMAGARD LIQUID ("accelerated switch") without breaking the blind.
All subjects were treated for 12 weeks with open-label GAMMAGARD LIQUID during initial stabilization (study period 1). Each subject was then randomized in a double-blind manner to continuation of GAMMAGARD LIQUID or withdrawal of GAMMAGARD LIQUID and replacement by placebo for 12 weeks (study period 2); subjects who did not tolerate treatment were immediately transitioned to open label GAMMAGARD LIQUID. After infusion of open-label GAMMAGARD LIQUID for 12 weeks (study period 3), subjects crossed-over to receive placebo or GAMMAGARD LIQUID for 12 weeks (study period 4). No subject was allowed to experience placebo more than one time during the study. At study end, subjects were treated with open-label GAMMAGARD LIQUID for 12 weeks (study period 5).
Overall, 69% (n=29) of subjects required an accelerated switch to open-label treatment with GAMMAGARD LIQUID during the placebo period due to functional deterioration, but did not switch when receiving GAMMAGARD LIQUID. The median number of treatment days using GAMMAGARD LIQUID was 84 and the median number of days using placebo was 28. One subject (2.4%) switched to open‑label treatment during blinded GAMMAGARD LIQUID cross-over period 1, but did not switch during placebo administration (p <0.001).
Forty-four subjects were evaluated to demonstrate effectiveness of GAMMAGARD LIQUID to improve or maintain muscle strength and functional ability in patients with MMN.
Statistical significance (p<0.001) favoring GAMMAGARD LIQUID over placebo was demonstrated by a substantially lower decline from baseline (22.30%; 95% CI: 9.92% to 34.67%) in mean grip strength in the more affected hand following treatment (see Table 14). The difference in relative change for GAMMAGARD LIQUID and placebo of 22.94% (95% CI: 10.69 to 35.19).
Table 14 Relative Change in Grip Strength in the More Affected Hand during Cross-over Period (ANOVA) (mIntent-to-Treat Dataset) No. of subjects (N=41)Statistics | Sequence 1 | Sequence 2 | Difference |
GAMMAGARD LIQUID | Placebo | Placebo | GAMMAGARD LIQUID | (GAMMAGARD LIQUID - Placebo) |
N | 22 | 22 | 19 | 20 A single subject in sequence 2, who was considered an outlier, was excluded from analysis | 41 |
Mean (SD) | -16.36 (32.84) | -30.52 (29.68) | -29.19 (39.95) | 1.46 (10.72) | 22.30 (39.21) |
Median | -3.90 | -27.00 | -25.03 | -0.11 | 26.6 |
Guy's Neurological Disability Scores (GNDS)12 for the upper limbs, reflecting both fine motor skills and proximal strength, showed a significant difference in efficacy between GAMMAGARD LIQUID and placebo at the 2.5% level in favor of GAMMAGARD LIQUID. GNDS is a patient orientated clinical disability scale designed for multiple sclerosis and is considered appropriate for other neurological disorders.
As determined by GNDS scores for the upper limbs, 35.7% of subjects deteriorated while receiving placebo but not during treatment with GAMMAGARD LIQUID, whereas 11.9% of subjects deteriorated during GAMMAGARD LIQUID but not during the placebo period. This difference was statistically significant (p=0.021) (see Table 15). Overall, 4.8% of subjects showed deterioration with both placebo and GAMMAGARD LIQUID, while 47.6% showed no deterioration using either.
Table 15 McNemar's Test for Subjects with Deterioration in Guy's Neurological Disability Score (Intent-to-Treat Dataset) No. of subjects (N=42)Deterioration on Placebo | 15 (35.7%) |
Deterioration on GAMMAGARD LIQUID | 5 (11.9%) |
Deterioration on both | 2 (4.8%) |
No deterioration | 20 (47.6%) |
When data from both treatment sequences were combined, a relative decline of ≥30% in grip strength in the more affected hand occurred in 42.9% of subjects during the placebo period, but not during treatment with GAMMAGARD LIQUID, whereas 4.8% of subjects experienced a ≥30% decline during treatment with GAMMAGARD LIQUID, but not during placebo. A relative decline of ≥30% in grip strength in the less affected hand occurred in 31.0% of subjects during the placebo period, but not during treatment with GAMMAGARD LIQUID. No subject experienced a ≥30% decline during treatment with GAMMAGARD LIQUID.
The Overall Disability Sum Score (ODSS) changed by -7.14% during placebo (indicating worsening of disability) and by -1.11% (indicating minimal change in disability) during treatment with GAMMAGARD LIQUID. For this specific analysis of ODSS, lower scores represented more disability.
With the dominant hand, subjects required 17% longer to complete the 9-hole peg test (a measure of dexterity) at the end of the placebo period, compared with baseline. By contrast, at the end of the GAMMAGARD LIQUID treatment period, subjects required 1.2% longer to complete the 9-hole peg test for the dominant hand compared with baseline. With the non-dominant hand, subjects required 33% longer to complete the 9-hole peg test at the end of the placebo period and 6.7% longer at the end of the GAMMAGARD LIQUID treatment period, compared with baseline.
Compared with baseline, assessment by subjects of physical functioning, as measured by visual analog scale (VAS) showed a mean change of 290% during placebo compared with baseline. Assessment by subjects of physical functioning showed a mean change of 73% during GAMMAGARD LIQUID treatment. Higher visual analog scale scores represent more severe disability.