MONOCLONAL PLASMA-CELLS IN THE BLOOD STEM-CELL HARVEST FROM PATIENTS WITH MULTIPLE-MYELOMA ARE ASSOCIATED WITH SHORTENED RELAPSE-FREE SURVIVAL AFTER TRANSPLANTATION

We sought to determine whether circulating tumor cells in the blood st em cell harvest from patients with multiple myeloma are associated wit h a shortened disease-free survival, Prospective analysis was performe d in 33 patients of blood obtained at leukapheresis for future transpl antation. An immunofluorescence microscopy procedure identified the tu mor cells by their morphology and monotypic light chain staining, Eigh teen patients had increased (greater than or equal to 0.2 x 10(6)/l) m onoclonal plasma cells circulating in the blood at stem cell harvest, Fifteen of the 18 have relapsed, with a median relapse-free survival o f 6.2 months, Of 15 patients with <0.2 x 10(6) cells/l, seven have rel apsed, with a median relapse-free survival of 22.5 months (P = 0.008). Patients with circulating plasma cells showed a trend toward shorter overall survival (P = 0.078). In a multivariate analysis using the bon e marrow plasma cell labeling index and beta(2)-microglobulin, the abs olute number of plasma cells in the stem cell harvest achieved borderl ine significance for predicting relapse-free survival (P = 0.057). In conclusion, increased monoclonal plasma cells in the blood stem cell h arvest are associated with a shortened relapse-free survival, This doe s not necessarily indicate that the circulating plasma cells were resp onsible for relapse, These results, however, have implications with re gard to the timing of obtaining blood stem cells for patients who are candidates for ablative chemotherapy.