Plasma ADA activity (pre-injection) should be determined every 1-2 weeks during the first 8-12 weeks of treatment in order to establish an effective dose of ADAGEN® (pegademase bovine) Injection. After 2 months of maintenance treatment with ADAGEN® (pegademase bovine) Injection, red cell dATP levels should decrease to a range of ≤ 0.005 to 0.015 μmol/mL. The normal value of dATP is below 0.001 μmol/mL. Once the level of dATP has fallen adequately, it should be measured 2-4 times a year during the remainder of the first year and 2-3 times a year thereafter, assuming no interruption in therapy.

Between 3 and 9 months, plasma ADA should be determined twice a month, then monthly until after 18-24 months of treatment with ADAGEN® (pegademase bovine) Injection.

Patients who have successfully been maintained on therapy for two years should continue to have plasma ADA measured every 2-4 months and red cell dATP measured twice yearly. More frequent monitoring would be necessary if therapy were interrupted or if an enhanced rate of clearance of plasma ADA activity develops.

Once effective ADA plasma levels have been established, should a patient’s plasma ADA activity level fall below 10 μmol/hr/mL (which cannot be attributed to improper dosing, sample handling or antibody development) then all patients receiving this lot of ADAGEN® (pegademase bovine) Injection will be required to have a blood sample for plasma ADA determination taken prior to their next injection of ADAGEN® (pegademase bovine) Injection.

Immune function, including the ability to produce antibodies, generally improves after 2-6 months of therapy, and matures over a longer period. Compared with the natural history of combined immunodeficiency disease due to ADA deficiency, a trend toward diminished frequency of opportunistic infections and fewer complications of infections has occurred in patients receiving ADAGEN® (pegademase bovine) Injection. However, the lag between the correction of the metabolic abnormalities and improved immune function with a trend toward diminished frequency of infections and complications of infection is variable, and has ranged from a few weeks to approximately 6 months. Improvement in the general clinical status of the patient may be gradual (as evidenced by improvement in various clinical parameters) but should be apparent by the end of the first year of therapy. Antibody to ADAGEN® (pegademase bovine) Injection may develop in patients and may result in more rapid clearance of ADAGEN® (pegademase bovine) Injection. Antibody to ADAGEN® (pegademase bovine) Injection should be suspected if a persistent fall in pre-injection levels of plasma ADA to < 10 μmol/hr/mL occurs. If other causes for a decline in plasma ADA levels can be ruled out [such as improper storage of ADAGEN® (pegademase bovine) Injection vials (freezing or prolonged storage at temperatures above 8°C), or improper handling of plasma samples (e.g., repeated freezing and thawing during transport to laboratory)], then a specific assay for antibody to ADA and ADAGEN® (pegademase bovine) Injection (ELISA, enzyme inhibition) should be performed.

In patients undergoing treatment with ADAGEN® (pegademase bovine) Injection, a decline in immune function, with increased risk of opportunistic infections and complications of infection, will result fr