Abatacept for the Treatment of Common Variable Immunodeficiency With Interstitial Lung Disease

Inclusion Criteria: 1. Diagnosis of CVID according to the international consensus document (ICON) 1. Age 4 years or above 2. Serum IgG at least 2 standard deviations below the age adjusted normal 3. Decreased serum IgA and/or serum IgM 4. Abnormal specific antibody response to immunization 5. Exclusion of secondary immunodeficiency 2. On replacement immunoglobulin for at least 6 months and willing to maintain throughout study 3. Granulomatous-lymphocytic interstitial lung disease with a lymphocytic component diagnosed by lung biopsy prior to study entry, wedge biopsy preferred. 4. Persistence or worsening of interstitial lung disease measured on serial CT imaging of the lung at least 6 months apart, with the latest assessment within 3 months of study entry. 5. Signed written informed consent 6. Willing to allow storage of biological specimens for future use in medical research. 7. Female subjects of childbearing potential must agree to an effective form of birth control such as hormone based contraceptive, intrauterine device, condoms/barrier, surgically sterile partner, or abstinence. 8. Fertile, non-vasectomized males with a female partner of childbearing potential should use condoms throughout the study and for 3 months after the last dose Exclusion Criteria: 1. History of hypersensitivity to abatacept or any of its components 2. Has received any lymphocyte depleting agents including anti-CD20 monoclonal antibodies, alemtuzumab, ATG in the preceding 6 months 3. Has received abatacept, cyclophosphamide, tumor necrosis factor inhibitors, or pulse steroids (defined as \>15mg/kg/day of methylprednisone or corticosteroid equivalent) within the past 3 months 4. Have started or increased any of the following immune modulating drugs within 3 months of enrolling and 3 months from initial CT chest: azathioprine, cyclosporine, tacrolimus, mercaptopurine, methotrexate, mycophenolate mofetil, or sirolimus 5. History of HIV infection (positive PCR) 6. Chronic untreated hepatitis B or C (positive PCR) 7. Active tuberculosis (TB) by positive QuantiFERON gold. If history of latent TB, then must supply evidence of completing treatment. 8. Persistent Epstein-Barr Virus (EBV) load ≥ 1,000 units/mL blood checked twice at least 1 month apart 9. Other uncontrolled infections 10. Live vaccine given within 6 weeks of the start of the trial 11. Malignancy or treated for malignancy within the past year 12. Currently pregnant or breast feeding 13. Life expectancy less than 1 month 14. Subjects unwilling to self-administer or have a parent/caregiver self-administer subcutaneous injections at home 15. Other conditions that the investigators feel contraindicate participation in the study Inclusion criteria for Extended Treatment Plan: * Patients must have completed the abatacept for the treatment of Interstitial Lung Disease in Common Variable Immunodeficiency (ABCVILD) trial * Patients must have demonstrated positive response to abatacept. * Patients must provide informed consent to participate in the Extended Treatment Plan. Exclusion criteria for Extended Treatment Plan: • Patients who experienced SAEs during the original trial, and such SAEs were determined as related to treatment, or patients who in the opinion of the investigator would not benefit from the extended treatment option.