METHOD OF ASSESSING RISK OF PML

1 . A method of evaluating the level of anti-JCV antibody in a sample, comprising:

(a) forming a first reaction mixture comprising a first aliquot of sample and a substrate on which is disposed HPVLP; and

(b) detecting the level of anti-JCV antibody bound to said substrate on which is disposed HPVLP by detecting a labeled detection reagent bound to anti-JCV antibody bound to said substrate;

wherein one or both of the following are met: (i) 20 ngs to 60 ngs of HPVP are disposed on said substrate and (ii) the ratio of sample to substrate is between 1:50 and 1:30,

thereby evaluating the level of anti-JCV antibody in a sample.

2 - 4 . (canceled)

5 . The method of claim 1 , further comprising

(c) forming a second reaction mixture containing a second aliquot of sample and solution-phase HPVLP, and detecting the level of unbound anti-JCV antibody in said second reaction mixture, such as by detecting anti-JCV antibody capable of binding with a substrate on which is disposed HPVLP; and

optionally (d) forming a third reaction mixture containing a third aliquot under conditions where anti-JCV antibodies in the sample are not bound by HPVLP or other antigen, and detecting the level of unbound anti-JCV antibody in the third reaction mixture, such as by detecting anti-JCV antibody capable of binding with a substrate on which is disposed HPVLP,

to provide a value for interference.

6 - 17 . (canceled)

18 . A kit comprising a substrate of claim 1 .

19 . (canceled)

20 . The kit of claim 18 , further comprising one or more or all of the following: HPVLP in solution; a JCV cut-off calibrator, an anti-JCV antibody positive control and a JCV negative control, which are samples of human sera; and reagents for detecting a complex containing anti-JCV antibodies bound to JCV antigen.

21 . (canceled)

22 . A method of evaluating a patient's risk of developing Progressive Multifocal Leukoencephalopathy (PML), the method comprising:

determining a JC Virus (JCV) antibody titer expressed as nOD, index or other unit, or other characteristics such as affinity or avidity expressed as percent inhibition in a anti-JCV antibody confirmation assay in a biological sample from the patient, wherein the anti-JCV antibody confirmation assay comprises a highly purified virus-like particle (HPVLP), wherein

if the titer or/and percent inhibition, or function of both values is determined to be above or below a pre-determined level, the patient is determined to be at a lower risk of developing PML, and wherein

if the titer or/and percent inhibition, or function of both values is determined to be above or below a pre-determined level, the patient is determined to be at an intermediate risk of developing PML, and wherein

if the titer or/and percent inhibition, or a function of both values is determined to be at or above the pre-determined level the patient is determined to be at a higher risk of developing PML, and further provided that either

(i) determining the anti-JCV antibody titer or percent inhibition in a sample of the patient comprises removing a biological sample from the patient's body or analyzing a sample from the patient, or

(ii) if the patient is determined to be at a lower risk of developing PML, administering a therapy to the patient.

23 . The method of claim 22 , wherein the patient is determined to be at a lower risk of developing PML, and the patient is administered an anti-VLA-4 therapy.

24 . The method of claim 22 , wherein the patient is determined to have a lower risk of PML if,

(i) the anti-JCV antibody titer as indicated by index value or nOD is determined to be <0.5, or

(ii) the anti-JCV antibody titer as indicated by index value or nOD is determined to be >0.5 and <3.0, and the percent inhibition is determined to be less than or equal to 70%.

25 . The method of claim 22 , wherein the patient is determined to have an intermediate risk of PML if,

(i) the anti-JCV antibody titer as indicated by index value or nOD is determined to be >0.5 and <1.5, and

(ii) the percent inhibition value is determined to be >70%.

26 . The method of claim 22 , wherein the patient is determined to have a higher risk of PML if,

(i) the anti-JCV antibody titer as indicated by index value or nOD is determined to be >3 and the percent inhibition value is determined to be >70%, or

(ii) the patient showed an increase in index, nOD or titer by 2-fold from a previous test.

27 . (canceled)

28 . The method of claim 22 , wherein the anti-JCV antibody titer is measured by an assay comprising:

(i) contacting the biological sample with HPVLPs under conditions suitable for binding of an anti-JCV antibody in the sample to an HPVLP;

(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%.

29 - 35 . (canceled)

36 . The method of claim 22 , wherein the anti-JCV antibody titer or percent inhibition is retested at 6 months or 12 month intervals.

37 . The method of claim 36 , wherein an increase in antibody titer or percent inhibition indicates an increase in the patient's risk of developing PML.

38 - 48 . (canceled)

49 . The method of claim 22 , further comprising:

(a) determining if the patient has received extended treatment with an anti-VLA-4 therapy; or

(b) determining if the patient has received a specified non-anti-VLA-4 immunosuppressant therapy; and

wherein the relative risk of PML for a patient who has an anti-JCV antibody titer or percent inhibition above a pre-determined level but has no specified prior immunosuppressant use and has not had an extended treatment with an anti-VLA-4 therapy is less than the relative risk of a patient who has an anti-JCV antibody titer or percent inhibition below a pre-determined level and has specified prior immunosuppressant use or an extended treatment with an anti-VLA-4 therapy, which is less than the relative risk of a patient who has an anti-JCV antibody titer or percent inhibition above a pre-determined level and has specified prior immunosuppressant use and extended treatment with an anti-VLA-4 therapy.

50 - 53 . (canceled)

54 . A method of evaluating a patient as a candidate to receive treatment with an anti-VLA-4 therapy, the method comprising acquiring:

a JC Virus (JCV) antibody titer and percent inhibition in a biological sample from the patient, wherein

if the antibody titer or percent inhibition is determined to be below a pre-determined level, then the patient is classified as being suitable for treatment with a first category of therapy, and wherein

if the antibody titer or percent inhibition is determined to be at or above the pre-determined level the patient is classified as being suitable for a second category of therapy, and

further provided that either

(i) acquiring the anti-JCV antibody titer and percent inhibition in a sample of the patient comprises removing a biological sample from the patient's body or analyzing a sample from the patient, and wherein the acquiring the anti-JCV antibody titer and percent inhibition in the sample comprises a highly purified virus-like particle (HPVLP) or

(ii) the method further comprises administering a therapy from the first category or the second category to the patient,

thereby evaluating the patient.

55 . The method of claim 54 , wherein

the first category of therapy is an anti-VLA-4 therap.

56 . The method of claim 54 , wherein the second category of therapy is an interferon, glatiramer acetate or a corticosteroid.

57 . The method of claim 54 , wherein the patient is classified as being suitable for treatment with a first category of therapy, and the patient is further administered natalizumab.

58 . The method of claim 54 , wherein the patient is classified as being suitable for treatment with a second category of therapy, and the patient is further administered interferon, glatiramer acetate or a corticosteroid.

59 - 65 . (canceled)

66 . A method of evaluating a patient's risk of developing Progressive Multifocal Leukoencephalopathy (PML), the method comprising,

(a) determining if the patient is negative or positive for exposure to JC Virus (JCV);

(b) determining if the patient has received extended treatment with an anti-VLA-4 therapy; or

(c) determining if the patient has received a specified non-anti-VLA-4 immunosuppressant therapy; and

responsive to a determination that the patient is negative for exposure to JCV, determining that a patient is at a relatively low risk of developing PML, or responsive to a determination that the patient is positive for JCV, that the patient has a relatively higher risk of developing PML;

wherein the relative risk of PML for a patient who has been exposed to JCV but has no specified prior immunosuppressant use and has not had an extended treatment with an anti-VLA-4 is less than the relative risk of a patient who has been exposed to JCV and has specified prior immunosuppressant use or an extended treatment with an anti-VLA-4, which is less than the relative risk of a patient who has been exposed to JCV and has specified prior immunosuppressant use and extended treatment with an anti-VLA-4.

67 . The method of claim 66 , further provided that either (i) determining that the patient is negative for JCV comprises removing a sample from the patient's body or analyzing a sample from the patient, or (ii) the method further comprises administering a therapy to the patient, or an alternative treatment to the patient.

68 - 85 . (canceled)

86 . A method of evaluating a patient's risk of developing Progressive Multifocal Leukoencephalopathy (PML), the method comprising:

determining a JC virus (JCV) antibody titer or percent inhibition in an anti-JCV antibody confirmation assay in a biological sample of the from the patient, wherein the anti-JCV antibody confirmation assay comprises a highly purified virus-like particle, and wherein the patient has a negative prior immunosuppressant exposure classification; wherein

if the titer and/or percent inhibition or a function of both values is determined to be above or below a pre-determined level, the patient is determined to be at a lower risk of developing PML, and wherein

if the titer and/or percent inhibition or a function of both values is determined to be above or below a pre-determined level, the patient is determined to be at an intermediate risk of developing PML, and wherein

if the titer and/or percent inhibition or a function of both values is determined to be above or below a pre-determined level, the patient is determined to be at a higher risk of developing PML.

87 . The method of claim 86 , wherein if the titer is determined to be above 1.5, the patient is determined to be at a higher risk of developing PML.

88 . The method of claim 86 , wherein if the titer is determined to be below 0.5, the patient is determined to be at a lower risk of developing PML.

89 . The method of claim 86 , wherein the titer is determined to be the same as a standard cut off calibrator having an index of about 1.

90 . The method of claim 86 , wherein the patient has been free of a non-anti-VLA-4 immunosuppressant therapy for a period within 1, 3, or 5 years.

91 . The method of claim 86 , wherein the patient has been free of a non-anti-VLA-4 immunosuppressant therapy for the patient's lifetime.

92 . The method of claim 86 , wherein the patient is monitored at regular intervals for a change in anti-JCV titer or percent inhibition.

93 . The method of claim 92 , wherein the patient is monitored every 6 months or 12 months.

94 . The method of claim 92 , wherein if the later assay indicates that the patient still has an anti-JCV antibody titer less than 0.5, then the patient is determined to be at a lower risk for developing PML.