Methods of treating a multiple sclerosis patient with anti-VLA-4 therapy

1. A method of treating a Multiple Sclerosis (MS) patient, the method comprising obtaining a biological sample from the patient, and responsive to a determination that the sample is negative for anti-JCV antibodies, administering to the patient an anti-VLA-4 therapy, said determination comprising:

measuring an anti-JC Virus (JCV) antibody titer reactivity index corresponding to an anti-JCV antibody titer by normalizing an OD value of the biological sample to a cut-off calibrator, said cut-off calibrator comprising a mixture of serum positive for anti-JCV antibodies and serum negative for anti-JCV antibodies and having a reactivity index of 1, wherein the anti-JCV antibody titer reactivity index is determined by an immunoassay to detect anti-JCV antibody in the sample;

classifying said sample as negative when said nOD value is less than 0.2 and positive when said nOD value is greater than 0.4, and responsive to a level of anti-JCV antibody corresponding to a nOD value between 0.2 and 0.4, measuring a percent inhibition by

(i) separating said biological sample into a first aliquot and a second aliquot and pre-incubating the first aliquot in absence of highly purified virus-like particle (HPVLPs) in solution and pre-incubating the second aliquot in presence of HPVLPs in solution under conditions suitable for binding of an anti-JCV antibody in the second aliquot to HPVLPs in solution; and

(ii) detecting a level of unbound anti-JCV antibody in each of the first aliquot and the second aliquot capable of binding to HPVLP disposed on a substrate to measure the percent to which HPVLP in solution inhibits anti-JCV antibody in the second aliquot from binding the HPVLP disposed on the substrate, and classifying said sample as negative when said inhibition is less than 45%.

2. The method of claim 1 , wherein said immunoassay to detect anti-JCV antibody comprises:

(i) contacting the biological sample with highly purified virus like particles (HPVLPs) under conditions suitable for binding of an anti-JCV antibody in the sample to HPVLP disposed on a substrate;

(ii) detecting the level of anti-JCV antibody binding in the sample to HPVLPs; and

(iii) correlating the detected level with a reference set, wherein the reference set is selected to indicate a false negative rate not greater than 3%.

3. The method of claim 1 , wherein the anti-JCV antibody titer or percent inhibition is retested at 3 months, 6 months or 12 month intervals.

4. The method of claim 3 , wherein an increase in anti-JCV antibody titer indicates an increase in the patient's risk of developing PML.

5. The method of claim 1 , wherein the anti-JCV antibody titer is measured before administration of the anti-VLA-4 therapy.

6. The method of claim 1 , wherein the anti-JCV antibody titer is measured during administration of the anti-VLA-4 therapy.

7. The method of claim 1 , further comprising determining that the patient has received treatment with an anti-VLA-4 therapy for less than 24 months.

8. The method of claim 1 , further comprising determining that the patient has not received a prior non-anti-VLA-4 immunosuppressant therapy.

9. The method of claim 8 , wherein the prior non-anti-VLA-4 immunosuppressant therapy is selected from beta-interferon, glatiramer acetate, mitoxantrone, methotrexate, azathioprine, cyclophosphamide, mycophenolate, anti-CD20 therapy, anti-CD11a therapy, and mycophenolate mofetil.

10. The method of claim 1 , wherein the anti-VLA-4 therapy is natalizumab.