Trial of anti IgE in RA.

1. Patients with refractory active rheumatoid arthritis (RA). Refractory disease is defined as persistent or relapsed disease activity despite conventional treatment, i.e. combination of disease modifying antirheumatic drugs including maximal tolerable doses of methotrexate. Active disease is defined as a DAS44 (Disease Activity Score of 44 joints) score of more than 3.6;

2. Presence of IgE-ACPA;

3. Age above 18 years;

4. WHO performance status 0, 1 or 2;

5. Informed consent according to rules and regulations of Leiden University Medical Center.

1. History of allergic or anaphylactic reaction to any therapeutic agent or known hypersensitivity to any component of anti-IgE monoclonal antibodies or to murine proteins;

2. No previous therapy with corticosteroids or a biological agent during the last 3 months;

3. No previous therapy with rituximab, leflunomide;

4. Life expectation of less than 6 months;

5. History of severe CNS disturbances and psychiatric problems;

6. Severe uncontrolled infections including parasitosis;

7. Irreversible major organ dysfunction, defined by any of the following criteria:

A. Creatinine clearance < 40 ml/min;

B. Left ventricular ejection fraction < 40%;

C. Pericardial effusion with haemodynamic consequences;

D. Resting arterial oxygen tension (PaO2) < 8 kPa (<60 mmHg) and / or resting arterial carbon dioxide tension (PaCO2) > 6.7 kPa (>50 mmHg);

E. Sustained 3-fold increase in serum transaminase or bilirubin.

8. HIV positivity;

9. Positive pregnancy test or unwillingness to use adequate contraception for the duration of the study;

10. History of cancer, including solid tumors, hematological malignancies and carcinoma in situ (except for basal cell and squamous cell carcinoma of the skin that have been treated and cured).