Autologous bone marrow transplantation in high-risk remission B-lineage acute lymphoblastic leukemia using a cocktail of three monoclonal antibodies (BA-1/CD24, BA-2/CD9, and BA-3/CD10) plus complement and 4-hydroperoxycyclophosphamide for ex vivo bone marrow purging.

Fourteen patients with high-risk B-lineage acute lymphoblastic leukemia (ALL) in complete remission underwent autologous bone marrow transplantation (BMT) using a combined immunochemopurging protocol. A monoclonal antibody (MoAb) cocktail of BA-1, BA-2, and BA-3 plus rabbit complement (C') plus 4-hydroperoxycyclophosphamide (4-HC) was used to eliminate residual occult leukemia cells from autografts. All patients were conditioned with single-dose total body irradiation (TBI) followed by high-dose Ara-C. All 14 patients engrafted at a median of 24 days (range, 12 to 36 days). Three patients are alive and disease free at 3.5 years, 3.9 years, and 4.1 years post-BMT. The Kaplan-Meiser estimate and standard error of the probability of sustained remission was 23% +/- 12% at 3.5 years post-BMT with a mean relapse-free interval of 1.4 +/- 0.4 years. The disease-free survival (DFS) at 3.5 years was 21% +/- 11%, with a mean DFS time of 1.3 +/- 0.4 years. A novel and quantitative minimal residual disease (MRD) detection assay, which combines fluorescence-activated multiparameter flow cytometry and cell sorting with leukemic progenitor cell (LPC) colony assays, was used to analyze remission BM samples from B-lineage ALL patients for residual LPC, and to evaluate the efficacy of ex vivo BM purging. Notably, the minimal residual leukemia burden before BMT, as measured by the percentage of B-lineage LPC in the pre-BMT remission BM samples, indicated the outcome of the BMT. The median value for the minimal residual leukemia burden before BMT was 0.0035% (35 LPC/10(6) mononuclear cells). The Kaplan-Meier estimates and standard errors of the probability of remaining in remission after BMT were 43% +/- 19% for patients whose BM samples contained less than or equal to 0.0035% LPC and 0% +/- 0% for patients whose BM samples contained greater than 0.0035% B-lineage LPC (P less than .05). In contrast to the minimal residual leukemia burden measured by the described MRD assay system, the percentage of blasts or TdT+ cells in the remission BM samples did not correlate with the probability of relapse. The applied purging protocol showed variable success in destroying target B-lineage LPC populations contaminating the autografts. While in some cases purging was highly effective, eliminating up to greater than or equal to 4 logs of residual B-lineage LPC, in other cases only 0.1 to 0.2 logs of B-lineage LPC were purged.(ABSTRACT TRUNCATED AT 400 WORDS)     

In vitro and in vivo radiation resistance associated with CD3 surface antigen expression in T-lineage acute lymphoblastic leukemia.

The radiobiologic features of primary clonogenic blasts (referred to also as T-lineage leukemic progenitor cells) from newly diagnosed and relapsed T-lineage acute lymphoblastic leukemia (ALL) patients were analyzed. Intrinsic radiation sensitivity differed substantially among primary clonogenic blasts from 34 newly diagnosed patients. The mean D0 (37% dose slope), SF2 (surviving fraction at 200 cGy), and alpha values (initial slope of the survival curve) were 141 +/- 15 cGy, 0.31 +/- 0.04, and 0.630 +/- 0.093 Gy-1, respectively. Among newly diagnosed cases, nine had SF2 values of greater than or equal to 0.50 and alpha values of less than or equal to 0.2 Gy-1, consistent with a marked intrinsic radiation resistance at the level of clonogenic blasts using the multitarget and linear quadratic models of cell survival. Of these nine radiation resistant cases, seven were CD3+. Furthermore, the mean D0 (162 +/- 20.8 cGy) and SF2 (0.377 +/- 0.057) values for the 20 CD3+ cases were significantly higher than the D0 (108.6 +/- 18.2 cGy) and SF2 (0.204 +/- 0.051) values for the 14 CD3- cases (P less than or equal to .05). Thus, clonogenic blasts from CD3+ newly diagnosed T-lineage ALL patients were more resistant to radiation than clonogenic blasts from CD3- newly diagnosed T-lineage ALL patients. Nineteen T-lineage ALL patients received autologous bone marrow transplants during complete remission. Pretransplant conditioning consisted of total body irradiation (TBI) combined with high-dose chemotherapy. Primary clonogenic blasts from patients who relapsed after bone marrow transplantation (BMT) displayed a particularly high degree of intrinsic radiation resistance with a mean D0 value of 333 cGy and an alpha value of 0.112 Gy-1. The expression of CD3 antigen appeared to predict the outcome of relapsed T-lineage ALL patients undergoing autologous BMT after TBI plus high-dose chemotherapy. The Kaplan-Meier estimates and standard errors of the probability of remaining in remission after BMT were 60% +/- 22% (mean relapse - free interval = 1.6 +/- 0.7 years) for CD3- patients and 0% +/- 0% (mean relapse - free interval = 0.2 +/- 0.0 years) for CD3+ patients (P = .002). Furthermore, the mean percentage of CD3-positive leukemic marrow blasts at presentation or relapse before BMT was significantly lower than the mean percentage of CD3-positive leukemic marrow blasts at relapse after BMT. Notably, in cultured leukemic bone marrow specimens from newly diagnosed as well as relapsed patients, colony blasts surviving in vitro radiation expressed CD3 more vividly than did colony blasts in unirradiated cultures.(ABSTRACT TRUNCATED AT 400 WORDS)     

Reactive oxygen intermediates activate NF-kappa B in a tyrosine kinase- dependent mechanism and in combination with vanadate activate the p56lck and p59fyn tyrosine kinases in human lymphocytes

We have previously observed that ionizing radiation induces tyrosine phosphorylation in human B-lymphocyte precursors by stimulation of unidentified tyrosine kinases and this phosphorylation is substantially augmented by vanadate. Ionizing radiation generates reactive oxygen intermediates (ROI). Because H2O2 is a potent ROI generator that readily crosses the plasma membrane, we used H2O2 to examine the effects of ROI on signal transduction. We now provide evidence that the tyrosine kinase inhibitor herbimycin A and the free radical scavenger N- acetyl-cysteine inhibit both radiation-induced and H2O2-induced activation of NF-kappa B, indicating that activation triggered by ROI is dependent on tyrosine kinase activity. H2O2 was found to stimulate Ins-1,4,5-P3 production in a tyrosine kinase-dependent manner and to induce calcium signals that were greatly augmented by vanadate. The synergistic induction of tyrosine phosphorylation by H2O2 plus vanadate included physiologically relevant proteins such as PLC gamma 1. Although treatment of cells with H2O2 alone did not affect the activity of src family kinases, treatment with H2O2 plus vanadate led to activation of the p56lck and p59fyn tyrosine kinases. The combined inhibition of phosphatases and activation of kinases provides a potent mechanism for the synergistic effects of H2O2 plus vanadate. Induction of tyrosine phosphorylation by ROI may thus lead to many of the pleiotropic effects of ROI in lymphoid cells, including downstream activation of PLC gamma 1 and NF-kappa B.     

In vivo radioprotective effects of recombinant human granulocyte colony-stimulating factor in lethally irradiated mice.

The purpose of this study was to investigate the in vivo radioprotective effects of recombinant human granulocyte colony stimulating factor (rhG-CSF) in lethally irradiated BALB/c mice. We initially analyzed the effects of increasing doses of rhG-CSF on survival of mice receiving 700 cGy (LD100/30) single dose total body irradiation (TBI). While 1 microgram/kg to 100 micrograms/kg doses of rhG-CSF were not radioprotective, a dose-dependent radioprotection was observed at 200 micrograms/kg to 4,000 micrograms/kg rhG-CSF. We next compared four different rhG-CSF treatment regimens side by side for their radioprotective effects in LD100/30 irradiated mice. One hundred percent of control mice receiving phosphate buffered saline died within 21 days after TBI with a median survival of 14 days. The median survival was prolonged to 20 days and the actuarial 60-day survival rate was increased to 27% when mice received 2,000 micrograms/kg rhG-CSF 24 hours before TBI (P = .0002; Mantel-Peto-Cox). Similarly, the median survival time was prolonged to 24 days and the actuarial 60-day survival rate was increased to 33%, when mice were given 2,000 micrograms/kg rhG-CSF 30 minutes before TBI. Optimal radioprotection was achieved when 2,000 micrograms/kg rhG-CSF was administered in two divided doses of 1,000 micrograms/kg given 24 hours before and 1,000 micrograms/kg given 30 minutes before TBI. This regimen prolonged the median survival time of LD100/30 irradiated mice to more than 60 days and increased the actuarial 60-day survival rate to 62% (P = .0001; Mantel-Peto-Cox). By comparison, no survival advantage was observed when mice received rhG-CSF 24 hours post-TBI. Similar radioprotective effects were observed when mice were irradiated with 650 cGy (LD80/30). The presented findings provide conclusive evidence that rhG-CSF has significant in vivo radioprotective effects for mice receiving LD100/30 or LD80/30 TBI.     

A requirement for protein kinase C inhibition for calcium-triggered apoptosis in acute lymphoblastic leukemia cells.

We have evaluated the cytotoxicities of the combinations of calcium mobilizers and PKC inhibitors against human acute lymphoblastic leukemia (ALL) cells. Here we report that calcium mobilizers alone or PKC inhibitors alone do not induce apoptosis in human ALL cells. However, the combinations of calcium mobilizers with potent inhibitors of PKC cause significant apoptosis in ALL cells. Our results provide experimental evidence that PKC blocks Ca2+-triggered apoptosis in human ALL cells. Thus, PKC inhibitors can be used to enhance the antileukemic activity of chemical or biological agents that trigger an apoptotic calcium signal in ALL cells. The exquisite sensitivity of ALL cells to calcium-dependent apoptosis in the presence of PKC inhibitors could provide the basis for new treatment programs against ALL.