Donor leukocyte infusions for chronic myeloid leukemia relapsed after allogeneic bone marrow transplantation.

PURPOSE: Treatment options for patients with chronic myeloid leukemia (CML) who relapse after allogeneic bone marrow transplantation (BMT) are limited. Treatment with lymphocytes from the original marrow donor and the influence on the malignant clone was studied in these patients. PATIENTS AND METHODS: Seven patients with CML that had relapsed after BMT with T-cell-depleted grafts were treated. Six patients received leukocyte infusions from the original marrow donor. One patient received a second BMT with unseparated marrow from the same sibling donor. Chimerism was studied using erythrocyte and cytogenetic markers. Residual leukemic cells were monitored by cytogenetic analysis of the Philadelphia (Ph) chromosome and by polymerase chain reaction (PCR) of the breakpoint cluster region/Abelson (BCR-ABL) fusion gene. RESULTS: In five patients with hematologic relapse, the Ph chromosome disappeared 1 to 3 months after the leukocyte infusions. Cytogenetic analysis and in situ hybridization (ISH) showed only donor cells during further follow-up. Four to five patients became negative for the BCR-ABL translocation by PCR. Graft-versus-host disease (GVHD) always preceded response and was severe in two patients. One patient with cytogenetic relapse showed no response after leukocyte infusions. GVHD after second BMT was of moderate severity. One year after second BMT, PCR for the BCR-ABL translocation was negative. CONCLUSION: Infusion of donor leukocytes is an effective treatment with a low mortality in patients with CML relapsed after BMT with a T-cell-depleted graft. Longer follow-up and more patients will be needed to know whether cure will be permanent.

Bax mutations in cell lines derived from hematological malignancies.

Many genes are involved in cell cycle control, DNA repair and induction of cell death. Alterations in these genes have been responsible for the development of cancer as well as for resistance to cancer therapy. Recently, an emerging family of bcl2-like genes has been identified that plays a role in the regulation of cell death. Its members are highly conserved in several domains which have been shown to be important for homodimerization or heterodimerization. The ratio between BAX/BCL2 heterodimers and BAX/BAX homodimers appears to be pivotal in deciding the life of death of a cell. We recently detected mutations in evolutionary highly conserved domains of the bax gene in cell lines derived from hematologic malignancies. Similar artificially generated mutations in other bcl2-like family members bcl2, bclxl, or ced9 have been shown to alter their function. This suggests a role for bax mutations in the multi-step pathogenesis of hematological malignancies.

An antisense Bcr-Abl phosphodiester-tailed methylphosphonate oligonucleotide reduces the growth of chronic myeloid leukaemia patient cells by a non-antisense mechanism.

The specificity of antisense oligonucleotides targeted to the mRNA breakpoint region of the Bcr-Abl oncogene, found in leukaemic cells from patients with chronic myeloid leukaemia, remains controversial due to non-specific effects. To prevent protein binding of oligonucleotides we designed and tested a methylphosphonate oligonucleotide with an attached 3' soluble phosphodiester tail. Growth of chronic myeloid leukaemia (CML) cell lines BV173, KCL-22 and cells of CML patients tested was inhibited by the b2a2 type antisense Bcr-Abl oligonucleotide and not with controls. Also the growth of control CD34+ cells of two healthy donors, control cell lines and cells from AML patients was only moderately affected or not affected. Bcr-Abl protein studies in combination with growth-determination experiments indicated that the antisense methylphosphonate Bcr-Abl oligonucleotide tested is a potent inhibitor of the growth of CML cells but works in a non-antisense manner.