Autografting in chronic granulocytic leukaemia

Safe mobilization of normal progenitors in advanced chronic myeloid leukemia with intensive chemotherapy and granulocyte-colony stimulating factor

Twenty-one patients with advanced chronic myeloid leukemia (late chronic phase (n = 8), accelerated phase (n = 11) and blast crisis (n = 2)) were treated with idarubicin, cytarabine, and etoposide followed by G-CSF and subsequent collection of peripheral blood progenitor cells in the early recovery phase. Treatment was reasonably well tolerated with no deaths or intensive care admissions. Despite the advanced phase of disease and heavy pretreatment with cytotoxics and interferon-alfa, 11 of 21 patients (52%) achieved a cytogenetic response. Of the nine major cytogenetic responses (complete (n = 3) and partial (n = 6)), seven achieved adequate progenitor collections for consideration for autologous transplantation. The only predictor of response was disease duration (P = 0.02). With a median follow-up of 1171 days from treatment it appears unlikely that G-CSF contributed to disease progression. Survival post-IcE was predicted by disease stage (P = 0.0001). Intensive chemotherapy followed by G-CSF allowed adequate yields of predominantly Philadelphia chromosome negative progenitor cells to be obtained from one-third of patients with advanced CML.

Multi-unit anti-BCR-ABL ribozyme therapy in chronic myelogenous leukemia

In this review, we summarize and update our data on the development of a multi-unit anti-BCR/ABL ribozyme. In vitro studies comparing several anti-BCR/ABL ribozymes demonstrated that a triple-unit ribozyme is the most efficient. Detailed kinetic analysis revealed this ribozyme to have a lower Kcat, most likely due to non homologous bases at restriction enzyme sites used in ribozyme construction. Delivery of this ribozyme to a BCR/ABL transformed cell line by a novel vehicle targeting the folate receptor resulted in a 3 log reduction in BCR/ABL mRNA when analyzed by RT-PCR. This delivery strategy reversed the IL-3 independence of this cell line. Retroviral vectors containing genes coding for the multi-unit ribozyme have been constructed and their use to effect BCR/ABL transformed cell biology is discussed.

Intensive combination chemotherapy and autologous bone marrow transplantation leads to the reappearance of Philadelphia chromosome-negative cells in chronic myelogenous leukemia

Fifteen patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML) who were ineligible for allogeneic bone marrow transplantation (BMT) or alpha-interferon therapy were included in this study. Eight patients were in the first late chronic phase, five were in the second chronic phase, one was in the accelerated phase, and one was in the blastic phase. Autologous bone marrow cells (median, 2.5 x 10(8) nucleated cells/kg) were stored at a median of 30 months after diagnosis. Patients were treated with cyclophosphamide (1.5 g/m2 daily for 4 days), carmustine (BCNU) (300 mg/m2), and etoposide (VP-16) (250 mg/m2 daily for 3 days) (CBV), followed by reinfusion of autologous bone marrow. Hematopoietic recovery was rapid, and toxicity was mild to moderate in 14 patients. One patient died of cytomegalovirus pneumonitis. Eight of 15 patients showed Ph suppression to less than 90% Ph-positive metaphases after autologous BMT. Major cytogenetic responses (Ph suppression to less than 35% Ph-positive metaphases) developed in four patients. Cytogenetic responses were observed in 4 of 11 patients infused with 100% Ph-positive marrows, and in all 4 patients infused with Ph-mosaic marrows (mixture of diploid and Ph-positive cells). Better results were observed when autologous BMT was performed in the chronic phase compared with the advanced phases. The major cytogenetic responses have lasted for 3, 4, 12, and 15+ months, whereas minor cytogenetic responses lasted for only a short time (less than 2 months). Three of seven patients (43%) in the chronic phase with previous resistance to alpha-interferon therapy became sensitive to alpha-interferon therapy after autologous BMT. The authors concluded that intensive chemotherapy followed by autologous BMT produced cytogenetic remissions in patients with Ph-positive CML and reinduced disease sensitivity to alpha-interferon therapy in patients previously resistant to it. This is particularly useful when treatment is given during the chronic phase and stem cells are collected at a time of previous cytogenetic remission.

Autografting for patients with chronic myeloid leukaemia in chronic phase: peripheral blood stem cells may have a finite capacity for maintaining haemopoiesis

We treated 14 patients with Ph-chromosome-positive chronic myeloid leukaemia still in chronic phase by autografting with blood-derived haemopoietic stem cells. Eleven patients were autografted electively after cytoreductive treatment with busulphan (16 mg/kg) and melphalan (60 mg/m2) and three were autografted after marrow cells from HLA-identical sibling donors had failed to engraft. In 13 patients haemopoiesis recovered; one failed to engraft and died 114 d after autografting. Two other patients became pancytopenic and received further stem cell transfusions at 3 and 40 months respectively after first autografting. One patient entered lymphoid transformation and died 14 months after autografting. Twelve patients survive at a median of 41 months (range 24-53) after autografting. Nine of the survivors have required further chemotherapy after autografting and four of the nine were electively autografted on a second occasion. Three patients surviving after autografting for 28, 43 and 53 months respectively have not required further chemotherapy. In two of these patients haemopoiesis is now predominantly Ph-negative. We conclude that autografting in chronic phase might prolong survival in some cases by reducing the size of the leukaemic stem cell population. The fact that initially successful grafts failed in two patients suggests that blood-derived stem cells may have a finite potential for self-replication.

Complete remission after autografting for chronic myeloid leukaemia

A previously untreated 31-yr old female with Ph-positive chronic myeloid leukaemia (CML) received busulphan and melphalan at high dosage followed by an autograft of peripheral blood stem cells collected 4 weeks earlier. Though recovering haemopoiesis was at first mainly Ph-positive, Ph-negative haemopoiesis predominated at 12 months and has persisted until the most recent study (24 months post-autograft). Her haemopoietic cells now show no rearrangement of the bcr gene, unlike the cells collected at diagnosis. Autografting carried out soon after diagnosis could be valuable for obtaining cytogenetic remissions in other patients with CML.

Autologous transplantation with circulating hemopoietic stem cells

Circulating stem cells exist in sufficient numbers in mouse, dog, and man to allow collection and transplantation after ablative treatment. Preclinical studies in the mouse have shown a low concentration, with a transplantation potential ratio of bone marrow to blood of 1:100. The ratio of circulating stem cells to bone marrow stem cells is more favorable in the dog (1:10-20). Recent pilot studies carried out in different centers with 10 patients have shown that this approach is feasible in man, too. It appears that 5 X 10(8) mononuclear cells/kg of body weight collected by seven or eight leukapheresis procedures of about 4 hrs each is sufficient for fast hemopoietic recovery after marrow ablative treatment. Potential advantages of the use of blood stem cells over bone marrow stem cells are the decreased likelihood of contamination with malignant cells, the avoidance of general anesthesia, and the infusion of immunocompetent cells, which might hasten immunorecovery in the autologous setting.