Treatment of Primary Humoral Immunodeficiency
In a prospective, open-label, single-arm, multicenter clinical study, 80 subjects with PI (with a diagnosis of XLA or CVID) received PRIVIGEN every 3 or 4 weeks for up to 12 months [see Clinical Studies (14.1)]. All subjects had been on regular IGIV replacement therapy for at least 6 months prior to participating in the study. Subjects ranged in age from 3 to 69; 46 (57.5%) were male and 34 (42.5%) were female.
The safety analysis included all 80 subjects, 16 (20%) on the 3-week schedule and 64 (80%) on the 4-week schedule. The median dose of PRIVIGEN administered was 428 mg/kg (3-week schedule) or 441 mg/kg (4-week schedule) and ranged from 200 to 888 mg/kg. A total of 1038 infusions of PRIVIGEN were administered, 272 in the 3-week schedule and 766 in the 4-week schedule.
Routine premedication was not allowed. However, subjects who experienced two consecutive infusion-related ARs that were likely to be prevented by premedication were permitted to receive antipyretics, antihistamines, NSAIDs, or antiemetic agents. During the study, 8 (10%) subjects received premedication prior to 51 (4.9%) of the 1038 infusions administered.
Table 2 summarizes the most frequent ARs that occurred in >5% of subjects.
Table 2. PI Pivotal Study – ARs Occurring in >5% of Subjects| AR
| Number (%) of Subjects [n=80] | Number (Rate) of Infusions with AR [n=1038] |
|---|
| Headache | 36 (45.0) | 100 (0.096) |
| Fatigue | 13 (16.3) | 29 (0.028) |
| Nausea | 11 (13.8) | 23 (0.022) |
| Chills | 9 (11.3) | 15 (0.014) |
| Vomiting | 9 (11.3) | 15 (0.014) |
| Back pain | 8 (10.0) | 15 (0.014) |
| Pain | 7 (8.8) | 14 (0.013) |
| Elevated body temperature | 7 (8.8) | 12 (0.012) |
| Diarrhea | 6 (7.5) | 6 (0.006) |
| Cough | 5 (6.3) | 5 (0.005) |
| Stomach discomfort | 5 (6.3) | 5 (0.005) |
Of the 192 ARs reported (including 5 serious, severe ARs described below) 91 were mild (awareness of sign, symptom or event, but easily tolerated), 81 were moderate (discomfort enough to cause interference with usual activity and may have warranted intervention), 19 were severe (incapacitating with inability to do usual activities or significantly affected clinical status, and warranted intervention), and 1 was of unknown severity.
The five serious ARs (hypersensitivity, chills, fatigue, dizziness, and increased body temperature, all severe), occurred in one subject, and resulted in the subject's withdrawal from the study. Two other subjects withdrew from the study due to ARs (chills and headache in one subject; vomiting in the other).
Seventy-seven of the 80 subjects enrolled in this study had a negative DAT at baseline. Of these 77 subjects, 36 (46.8%) developed a positive DAT at some time during the study. However, no subjects showed evidence of hemolytic anemia.
During this study, no subjects tested positive for infection due to human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), or B19 virus (B19V).
An extension of the study described above was conducted in 55 adult and pediatric subjects with PI to collect additional efficacy, safety, and tolerability data. This study included 45 subjects from the pivotal study who were receiving PRIVIGEN and 10 new subjects who were receiving another IGIV product prior to enrolling in the extension study. Subjects ranged in age from 4 to 81 years; 26 (47.3%) were male and 29 (52.7%) were female.
Subjects were treated with PRIVIGEN at median doses ranging from 286 to 832 mg/kg per infusion over a treatment period ranging from 1 to 27 months. Twelve (21.8%) subjects were on a 3-week treatment schedule with the number of infusions per subject ranging from 4 to 38 (median: 8 infusions); 43 (78%) subjects were on a 4-week schedule with the number of infusions ranging from 1 to 31 (median: 15 infusions). A total of 771 infusions were administered in this study.
In this study, subjects who continued from the pivotal study were permitted to receive infusions of PRIVIGEN at a rate up to 12 mg/kg/min (as opposed to the maximum of 8 mg/kg/min allowed in the pivotal study) at the discretion of the investigator based on individual tolerability. Twenty-three (51%) of the 45 subjects from the pivotal study (42% of the 55 subjects in the extension study) received 265 (38%) infusions at a maximum rate greater than the recommended rate of 8 mg/kg/min [see Dosage and Administration (2.5)]. The median of the maximum infusion rate in this subset was 12 mg/kg/min. However, because the study was not designed to compare infusion rates, no definitive conclusions regarding tolerability could be drawn for infusion rates higher than the recommended rate of 8 mg/kg/min.
Table 3 summarizes the ARs that occurred in >5% of subjects.
Table 3. PI Extension Study – ARs Occurring in >5% of Subjects| AR
| Number (%) of Subjects [n=55] | Number (Rate) of Infusions with AR [n=771] |
|---|
| Note: The AR rates in this study cannot be compared directly to the rates in other IGIV studies, including the original pivotal study described earlier in this section, because (1) the extension study used an enriched population and (2) the selective use of higher infusion rates at the investigators' discretion in a subset of subjects may have introduced bias. |
| Headache | 18 (32.7) | 76 (0.099) |
| Nausea | 6 (10.9) | 10 (0.013) |
| Elevated body temperature | 4 (7.3) | 12 (0.016) |
| Abdominal pain
| 4 (7.3) | 7 (0.009) |
| Chest pain | 3 (5.5) | 4 (0.005) |
| Chills | 3 (5.5) | 7 (0.009) |
| Joint swelling/effusion | 3 (5.5) | 7 (0.009) |
| Pain | 3 (5.5) | 6 (0.008) |
| Fatigue | 3 (5.5) | 5 (0.006) |
| Influenza-like illness | 3 (5.5) | 5 (0.006) |
| Pharyngolaryngeal pain | 3 (5.5) | 4 (0.005) |
| Urticaria | 3 (5.5) | 4 (0.005) |
| Dizziness | 3 (5.5) | 3 (0.004) |
Of the 125 reported ARs, 76 were mild (did not interfere with routine activities), 40 were moderate (interfered somewhat with routine activities), and 9 were severe (impossible to perform routine activities).
Three subjects experienced ARs: dyspnea and pancytopenia in one subject, a transient ischemic attack 16 days after the infusion in one subject, and mild urticaria in one subject, resulting in the subject's withdrawal from the study.