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

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.