Methods of treating inflammatory and autoimmune diseases with natalizumab

A method for treating an inflammatory or autoimmune disease, comprising:

• (a) determining an amount of IgG4 in a patient's plasma or serum;
• (b) administering a first dose of an IgG4 anti-VLA-4 antibody to the patient for a first dosage period, wherein, in the event the amount of IgG4 in the patient's plasma or serum is below 200 μg/mL, the first dose is lower than 300 mg by IV infusion and/or the first dosage period is longer than four weeks;
• (c) monitoring an amount of bivalent IgG4 anti-VLA-4 antibody in the patient's plasma or serum during the first dosage period;
• (d) determining a second dose and second dosage period of the IgG4 anti-VLA-4 antibody based on the amount of IgG4 in the patient's plasma or serum and on the amount of bivalent IgG4 anti-VLA-4 antibody in the patient's plasma or serum;
• and
• (e) administering the second dose of the IgG4 anti-VLA-4 antibody for the second dosage period;
• wherein if monitoring shows that bivalent IgG4 anti-VLA-4 antibody in the patient's plasma or serum remains above a predetermined level during the first dosage period, then the second dose of the IgG4 anti-VLA-4 antibody administered over the second dosage period is designed to achieve a reduction of the amount of bivalent IgG4 anti-VLA-4 antibody to below the predetermined level during at least a portion of the second dosage period;
• wherein the second dose and second dosage period improve safety and/or efficacy of the treatment;
• wherein the predetermined level of bivalent IgG4 anti-VLA-4 antibody in the patient's plasma or serum during the first dosage period is selected from 0.1 ug/mL, 0.5 ug/mL, and 1 ug/m;
• and
• wherein the second dose is lower than 300 mg by IV infusion and/or the second dosage period is longer than four weeks in the event the amount of IgG4 in the patient's plasma or serum during the first dosage period is below 200 μg/mL.