Lack of patients with a condition of interest that resulted in failure to recruit

The investigators goal is to evaluate the role of XOLAIR® in treatment of Acute Tubulointerstitial Nephritis (AIN) with the goal of shortening the duration and dose of prednisone for treatment of drug-induced AIN. Currently there is no good treatment for drug-induced AIN. Prednisone is the standard treatment but is associated with many side-effects when used long-term and at high doses.

Inclusion Criteria:

1. Adult subjects > 18 years old of both genders
2. Biopsy proven acute interstitial nephritis in the native kidneys without evidence of ischemic or glomerular pathology in the biopsy
3. Normal baseline creatinine defined as estimated GFR ≥ 60 ml/min/SA based on MDRD calculation within 1 year prior to renal biopsy
4. Serum creatinine elevation of > 0.3 mg/dL and/or doubling of serum creatinine compared to most recent documented creatinine available (at least within the last year)
5. No immunosuppressants in the last three months including prednisone
6. Women of childbearing potential not using the contraception method can be included as this is a one time dosing and has no known long-term effects.

Exclusion Criteria:

1. Unwillingness to give consent
2. Patients who are Pregnant (positive serum pregnancy test for females) or breast feeding
3. Documented history of an autoimmune disease
4. Inability or unwillingness to take prednisone for the prescribed duration and/or dose
5. Subjects suspected to have non-drug-induced AIN
6. Subjects not meeting the inclusion criteria
7. Subjects with contraindication to administration of omalizumab
8. Prior use of omalizumab
9. Severe hypersensitivity to omalizumab or any component of the product
10. Known elevated IgE level from other disease processes
11. Subjects taking (nonsteroidal antiinflammatory drug) NSAIDs chronically
12. Use of any other investigational agents in the last 30 days
13. Patients with severe medical condition(s) including metastatic cancer, terminal congestive heart failure, severe ischemic heart disease or any other medical condition in which life expectancy is less than 6 months.

Open Label