Methods and materials for assessing response to plasmablast- and plasma cell-depleting therapies

1. A method of treating a disease in a patient, the method comprising:

a) measuring the level of CD38-expressing cells in the patient relative to a control subject without the disease, wherein the CD38-expressing cells are plasmablasts and plasma cells; and

b) administering a therapeutically effective amount of an anti-CD38 antibody to the patient, wherein the disease is an autoimmune disease, and the patient was shown to have, following treatment with an anti-CD20 antibody, an elevated level of CD38-expressing cells relative to the control subject, and wherein the anti-CD38 antibody is an isolated antibody that specifically binds human CD38 (SEQ ID NO:1) and comprises:

a) a heavy chain variable region comprising:

i) a first CDR comprising SEQ ID NO:3;

ii) a second CDR comprising SEQ ID NO:4; and

iii) a third CDR comprising SEQ ID NO: 5; and

b) a light chain variable region comprising:

i) a first CDR comprising SEQ ID NO:6;

ii) a second CDR comprising SEQ ID NO:7; and

iii) a third CDR comprising SEQ ID NO:8

wherein a biological sample obtained from the patient following treatment with the anti-CD20 antibody was shown to have

i) an elevated level of CD38-expressing plasmablasts and plasma cells relative to the control subject by assaying for free Ig light chains, and

ii) an elevated level of at least one gene enriched in the CD38-expressing cell relative to the control subject, wherein the at least one gene is CD38 or IgJ, wherein the anti-CD38 antibody depletes the plasmablasts and plasma cells after being administered, and

wherein the patient treated with the anti-CD38 antibody exhibits a dose-dependent reduction in the plasmablasts and plasma cells.

2. The method of claim 1 , wherein the heavy chain variable region comprises SEQ ID NO:9.

3. The method of claim 1 , wherein the light chain variable region comprises SEQ ID NO:10.

4. The method of claim 1 , wherein the heavy chain variable region comprises SEQ ID NO:9 and the light chain variable region comprises SEQ ID NO:10.

5. The method of claim 1 , wherein the anti-CD38 antibody comprises a heavy chain comprising SEQ ID NO:21 and a light chain comprising SEQ ID NO:22.

6. The method of claim 1 , wherein the anti-CD38 antibody further comprises an Fc domain.

7. The method of claim 6 , wherein the Fc domain is a human Fc domain.

8. The method of claim 7 , wherein the Fc domain is a variant Fc domain.

9. The method of claim 1 , wherein a biological sample obtained from the patient following treatment with the anti-CD20 antibody was shown to have an elevated level of the CD38-expressing cells relative to the control subject by flow cytometry.

10. The method of claim 9 , wherein the CD38-expressing cells were stained with a second anti-CD38 antibody conjugated to a fluorochrome.

11. The method of claim 1 , wherein the anti-CD38 antibody interacts with at least K121, F135, Q139, D141, E239, W241, C275, K276, F284, P291 and E292 of SEQ ID NO:1.

12. The method of claim 1 , wherein the autoimmune disease is selected from the group consisting of myasthenia gravis, autoimmune thrombocytopenia, immune mediated thrombocytopenia, idiopathic thrombocytopenia purpura, thrombotic thrombocytopenia purpura, rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, ulcerative colitis, graft-versus host disease, myasthenia gravis, Sjogren's syndrome, multiple sclerosis, and autoimmune thyroiditis.

13. The method of claim 12 , wherein the autoimmune disease is systemic lupus erythematosus.

14. The method of claim 1 , wherein the patient is unresponsive to CD20 based therapies.