Immunologic purging of marrow assessed by PCR before autologous bone marrow transplantation for B-cell lymphoma

The use of autologous bone marrow transplantation is increasing in the management of advanced cancers. Many investigators have attempted to "purge" autologous marrow of residual tumor cells because of concern that reinfused tumor cells might contribute to relapse. The efficacy of purging remains unproved.

We performed clonogenic assays in a tumor cell line in culture to determine the efficiency of immunologic purging. Amplification by the polymerase chain reaction (PCR) was used to detect residual lymphoma cells before and after purging of bone marrow from 114 patients with B-cell non-Hodgkin's lymphoma in whom a translocation (t(14;18] that could be amplified by PCR was detected at the time of their initial evaluation.

Immunologic purging in vitro resulted in a 3-to-6-log destruction of cells in the tumor cell line. Residual lymphoma cells were detected by PCR in the bone marrow of all patients before purging. No lymphoma cells could be detected in the marrow of 57 patients after purging. Disease-free survival was increased in these 57 patients as compared with those whose marrow contained detectable residual lymphoma (P less than 0.00001). The ability to purge residual lymphoma cells was not associated with the degree of bone marrow involvement (P = 0.4494) or the previous response to therapy (P = 0.1298).

The inability to purge residual lymphoma cells was the most important prognostic indicator in predicting relapse. These results provide evidence of the clinical usefulness of ex vivo purging of autologous bone marrow in the treatment of patients with lymphoma and suggest that the reinfusion of malignant cells in autologous marrow contributes to relapse