Conditional survival analysis of Multiple Myeloma patients: experience of the Comprehensive Cancer Center Freiburg (CCCF) University Medical Center Freiburg

The high-level production of antibody molecules by multiple myeloma (MM) cells makes them susceptible to killing by bortezomib and other proteosome inhibitors, but may also make normal plasma cells (PC, responsible for sustaining protective antibody titers elicited by vaccination or infection) susceptible to these agents. This in turn may make bortezomib-treated patients susceptible to reinfection and would necessitate re-immunization. However, it has not been determined if bortezomib treatment actually affects normal PC and compromises vaccine-induced antibody titers in patients. The primary objective of our study is to determine whether bortezomib treatment affects the antibody titers against common viral and vaccine antigens. 25 newly diagnosed MM patients patients (to date) treated with bortezomib + dexamethasone (with the later addition of lenalidomide in some patients) were assayed for antibody titers against mumps (IgG), rubella (IgG), Epstein Barr (IgG), varicella zoster, tetanus and diptheria prior to treatment, and then after 1, 3, 6 cycles of treatment and 4 months after completion. Unexpectedly, we found that bortezomib treatment either had no effect, or significantly increased some (but not all) antibody titers in individual patients (Fig. 1). 52% of the patients had increases in titers against EBV, 48% against mumps, 40% against varicella, 32% against rubella, 12% against diphtheria and 8% against tetanus. Since normal PC do not proliferate, this reconstitution of antibody titers in patients that were not re-vaccinated suggests previously unrecognized and novel plasma cell biology. PO-168 Conditional survival analysis of Multiple Myeloma patients: experience of the Comprehensive Cancer Center Freiburg (CCCF) University Medical Center Freiburg J.M. Waldschmidt, I. Promny, S. Hieke, M. Schinke, G. Ihorst, M. Pantic, J. Duyster, R. Wasch, M. Schumacher, M. Engelhardt University of Freiburg Medical Center, Department of Hematology, Oncology and Stem Cell Transplantation; Institute of Medical Biometry and Medical Informatics, University Medical Center Freiburg; Clinical Trials Unit, University of Freiburg Medical Center, Freiburg, Germany