The relationship between monoclonal myeloma precursor B cells in the peripheral blood stem cell harvests and the clinical response of multiple myeloma patients

The aim of this study was to determine the presence of monoclonal myeloma p recursor B cells in peripheral blood stem cell harvests and to investigate their role in the clinical outcome of multiple myeloma patients. A total of 39 multiple myeloma patients were treated with a sequential therapy includ ing double high-dose melphalan therapy followed by a double transplant proc edure. The apheresis products for the second transplant were purged using a panel of four or five different mouse monoclonal antibodies against B-cell antigens (CD10, CD19, CD20, CD22 and CD37, In 19/39 patients a tumour-spec ific CDR III signal was identified in the diagnostic bone marrow Gene scan analysis after CDR LII PCR of the magnetic bead isolated B-cell fraction fr om the apheresis products in these 19 patients revealed three different pat terns: 32% of patients had a predominantly monoclonal B-cell population: 63 % of patients had an identifiable monoclonal signal within an oligoclonal B -cell population, In only 1/19 patients were no monoclonal B cells identifi ed in the B-cell population of the apheresis product. A correlation between the clonal pattern and the clinical response after sequential chemotherapy was found. Patients with a predominance of monoclonal myeloma or myeloma p recursor B cells had an early relapse or achieved a minimal response or a p artial remission. Patients with an oligo- and/or polyclonal pattern achieve d a high percentage of partial as well as complete remissions.