Selective ablation of acute myeloid leukemia using antibody-targeted chemotherapy: a phase I study of an anti-CD33 calicheamicin immunoconjugate

Leukemic blast cells express the CD33 antigen in most patients with acute myeloid leukemia (AML), but this antigen is not expressed by hematopoietic stem cells. We conducted a study to determine whether normal hematopoiesis could be restored in patients with AML by selective ablation of cells expressing the CD33 antigen. In a dose escalation study, 40 patients with relapsed or refractory CD33(+) AML were treated with an immunoconjugate (CMA-676) consisting of humanized anti-CD33 antibody linked to the potent antitumor antibiotic calicheamicin. The capacity of leukemic cells to efflux 3, 3'-diethyloxacarbocyanine iodide (DiOC2) was used to estimate pretreatment functional drug resistance. Leukemia was eliminated from the blood and marrow of 8 (20%) of the 40 patients; blood counts returned to normal in three (8%) patients. A high rate of clinical response was observed in leukemias characterized by low dye efflux in vitro. Infusions of CMA-676 were generally well tolerated, and a postinfusion syndrome of fever and chills was the most common toxic effect. Two patients who were treated at the highest dose level (9 mg/m2) were neutropenic >5 weeks after the last dose of CMA-676. These results show that an immunoconjugate targeted to CD33 can selectively ablate malignant hematopoiesis in some patients with AML.

Isolated tetrasomy 8 in minimally differentiated acute myeloid leukemia (AML-M0)

Tetrasomy 8 as a sole anomaly in hematological disorders is relatively rare. To the best of our knowledge, only 19 such cases have been described in the literature to date. Of them, acute myeloid leukemia (AML) in 13 (M1, one; M2, three; M4, one; M5, eight), acute lymphoblastic leukemia(ALL) in one, myelodysplastic syndrome(MDS) in 3, polycythemia vera(PV) and myelofibrosis(MF), one case each. Their median survival was 20 weeks. Here, we report the first case of a 29-year-old man with minimally differentiated AML (AML-M0) displaying a tetrasomy 8 clone. Immunophenotyping showed positivity with CD33, CD34 and intracellular MPO, but all lymphoid markers tested were negative. Conventional cytogenetics of bone marrow cells showed 84.9% of metaphases with tetrasomy 8 in addition to 15.1% with normal diploidy. However, Fluorescence in situ hybridization(FISH) using a centromeric probe specific for chromosome 8 revealed trisomy 8 in 14.2% of interphase nuclei besides tetrasomy 8 in 82.4%. The patient died four weeks after diagnosis without therapy. In conclusion, these findings suggest that tetrasomy 8 is associated with a heterogeneous group of myeloid disorders and heralds a bad prognosis. It may be a consequence of clonal evolution of trisomy 8.

Clonal evolution of aplastic anaemia to myelodysplasia/acute myeloid leukaemia and paroxysmal nocturnal haemoglobinuria

Aplastic anaemia (AA) is a non-malignant haemopoietic disorder characterised by peripheral blood pancytopenia and a hypocellular bone marrow. Successful management of acquired AA including treatment with immunosuppressive agents, mainly antithymocyte globulin (ATG) and cyclosporin or allogeneic haemopoietic stem cell transplantation, has resulted in long-term survival of many patients. The later evolution of complicating clonal disorders such as paroxysmal nocturnal haemoglobinuria, myelodysplasia and acute myeloid leukaemia in patients treated with immunosuppressive therapy may be a manifestation of the natural history of the aplasia, the development of which may or may not be increased by immunosuppressive therapy. A persistent, profound deficiency and/or defect in the stem cell compartment, despite haematological recovery after immunosuppressive therapy, may create an unstable situation which predisposes to later clonal disorders. A review of the progression of AA to clonal disorders is now outlined.

[Cell adhesion molecules: expression and function in acute myeloid leukemia]

Adhesion molecules play a major role in the regulation of normal hematopoiesis. Precursor/cell matrix/endothelial interactions determine retainment or release of hematopoietic cells from the bone marrow microenvironment. Consequently, changes in the affinity or quantitative expression of adhesion molecules on either the bone marrow stroma or the cell precursor component during a malignant process will affect cell attachment. Adhesion molecules, therefore, are modulator molecules which alter the biological behavior of leukemic cells in terms of migration and localization properties. Several membrane-bound adhesion molecules and, in some instances, their soluble counterparts which may be biologically active, have been described in acute myeloid leukemia. The panel of receptors expressed demonstrates heterogeneity between various cases of acute myeloid leukemia. There is generally no correlation between the adhesion receptor phenotype and the morphologic or clinical features of acute leukemia. These receptors function in interactions of leukemic blasts with the cellular and matrix components of the marrow microenvironment. Adhesive interactions may influence the proliferation and survival of leukemic cells. However, the precise role that these molecules play in the generation and sustenance of the leukemic state remains undetermined.

Activation of c-Abl tyrosine kinase requires caspase activation and is not involved in JNK/SAPK activation during apoptosis of human monocytic leukemia U937 cells

Genotoxic stress triggers the activation of several sensor molecules, such as p53, JNK1/SAPK and c-Abl, and occasionally promotes the cells to apoptosis. We previously reported that JNK1/SAPK regulates genotoxic stress-induced apoptosis in p53-negative U937 cells by activating caspases. c-Abl is expected to act upstream of JNK1/SAPK activation upon treatment with genotoxic stressors, but its involvement in apoptosis development is still unclear. We herein investigated the kinase activities of c-Abl and JNK1/SAPK during apoptosis elicited by genotoxic anticancer drugs and tumor necrosis factor (TNF) in U937 cells and their apoptosis-resistant variant UK711 cells. We found that the activation of JNK1/SAPK and c-Abl correlated well with apoptosis development in these cell lines. Unexpectedly, however, the JNK1/SAPK activation preceded the c-Abl activation. Moreover, the caspase inhibitor Z-Asp suppressed c-Abl activation and the onset of apoptosis but not the JNK1/SAPK activation. Interestingly, c-Abl tyrosine kinase inhibition by CGP 57148 reduced apoptosis without interfering with JNK1/SAPK activation. These results indicate that c-Abl acts not upstream of JNK1/ SAPK but downstream of caspases during the development of p53-independent apoptosis and is possibly involved in accelerating execution of the cell death pathway.

Structure-activity relationships of flavonoids and the induction of granulocytic- or monocytic-differentiation in HL60 human myeloid leukemia cells

The flavones apigenin and luteolin strongly inhibited the growth of HL60 cells and induced morphological differentiation into granulocytes. The flavonol quercetin inhibited the cell growth and induced a differentiation marker, i.e., NBT reducing ability. However quercetin-treated cells were not morphologically differentiated into granulocytes. The chalcone phloretin weakly induced NBT reducing ability and a marker of monocytic differentiation alpha-naphthyl butyrate esterase activity in the cells. Quercetin and phloretin appeared to induce the differentiation of HL60 cells into monocytes. The proportion of alpha-naphthyl butyrate esterase-positive cells induced by genistein was less than that of the NBT-positive cells. Some of the nuclei in genistein-treated HL60 cells morphologically changed. Genistein must have induced both granulocytic and monocytic differentiation of HL60 cells. The flavonols galangin and kaempferol, which had fewer hydroxyl group(s) in the B-ring than quercetin, and the flavanone naringenin inhibited the growth but did not induce the differentiation of HL60 cells.

Autologous bone marrow transplantation for acute myeloid leukemia using 4-hydroperoxycyclophosphamide-purged bone marrow and the busulfan/etoposide preparative regimen: a follow-up report

We studied the use of autologous bone marrow transplantation (ABMT) as treatment for acute myeloid leukemia (AML) in adults up to age 60. We used a preparative regimen of busulfan 16 mg/kg plus etoposide 60 mg/kg and bone marrow purged with 100 microg/ml of 4-hydroperoxycyclophosphamide (4HC). We treated 50 first remission patients; there were two treatment-related deaths and 13 relapses. With median follow-up of 6.8 years (minimum 4.5) disease-free survival (DFS) is 70%, relapse rate 27% and overall survival 72%. Patients with favorable cytogenetics had DFS 78% and relapse 18% whereas unfavorable patients had DFS 63% and relapse rate 35%. For 25 patients in second or third remission there were five treatment-related deaths and seven relapses. DFS is 52% and relapse rate 35%. None of six patients with primary refractory AML had long-term disease control. These data support the use of ABMT with an intensive preparative regimen and purged bone marrow as a highly effective treatment for adults with AML.

[The role of cytokines in the pathology of acute myeloid leukemia]

An overview of literature data concerning the role of some cytokines in growth regulation of acute myeloid leukemia cells is presented. Clinical application of cytokines in anti-leukemia therapy is also discussed.

Intestinal permeability in patients with acute myeloid leukemia

Intestinal permeability was studied in patients with acute myeloid leukemia (AML) before, during and after chemotherapy. Intestinal permeability was determined by the lactulose (La)/mannitol (Ma) absorption test in 16 adult patients with de novo AML. The hydrogen breath test was used to disclose bacterial fermentation of the test substances in the small intestine. The permeability was found significantly increased (p<0.02) in the patients before induction chemotherapy treatment. During induction treatment and throughout the cytopenic period the intestinal permeability was constantly and significantly increased, compared with controls. In patients with abnormally increased permeability, no increase in hydrogen breath test result was noted. From our results it can be concluded that increased intestinal permeability is present in AML patients before commencing chemotherapy. Factors other than chemotherapy would seem to be more important regarding the occurrence of intestinal disturbances in these patients.

Bone mineral density in women with cytotoxic-induced ovarian failure

OBJECTIVE

Premature ovarian failure is associated with a reduction in bone mineral density. As survival rates following treatment for haematological malignancies improve, chemotherapy-induced ovarian failure is becoming more common. However, there are few data concerning the impact of this on bone mineral density (BMD). We have therefore measured the BMD in 33 women with ovarian failure following treatment with cytotoxic chemotherapy.

PATIENTS AND DESIGN

We studied 33 women who received combination chemotherapy for Hodgkin's disease (n = 27), non-Hodgkin's lymphoma (n = 4), sarcoma (n = 1) and acute myeloid leukaemia (n = 1). The mean (range) age of the subjects at the time of BMD measurement was 37.5 (24-50) years and the mean (median: range) duration of amenorrhoea was 49 (24: 5-277) months. Eleven women had received hormone replacement therapy (HRT) for a mean (range) duration of 25 (1-62) months. BMD was measured by single photon absorptiometry or single X-ray absorptiometry, and dual energy X-ray absorptiometry at the distal and proximal radius, the femoral neck and the lumbar spine, respectively. BMD was expressed as Z-scores and statistical analysis was performed using the Wilcoxon matched-pairs signed-rank test.

RESULTS

There was no significant reduction in BMD at the hip, spine or a forearm in the cohort as a whole, although there was a trend to reduce bone density at all sites. When patients who had received HRT were excluded from the analysis there were small reductions in mean BMD at all sites, but this was only statistically significant at the proximal forearm (Z-score = -0.65; P = 0.03). Mean BMD of the HRT-treated patients was normal at all sites. Only seven patients (21%) had a BMD Z-score < -2 at any site.

CONCLUSION

It is inappropriate to assume that ovarian failure from different aetiologies has a similar deleterious impact on the skeleton. Untreated premature ovarian failure following cytotoxic chemotherapy results in some reduction in bone mineral density, but this is of a minor degree and is less than that observed in other hypo-oestrogenic states. The reason for this is unclear but studies of residual hormone production in the cytotoxic-damaged ovary may provide an answer.

Anticoagulant effects of 1alpha,25-dihydroxyvitamin D3 on human myelogenous leukemia cells and monocytes

The hormonally active form of vitamin D is 1alpha, 25-dihydroxyvitamin D3 [1,25(OH)2D3], which is a principal regulator of calcium homeostasis. It also affects hormone secretion, cell differentiation, and proliferation by a mode of action that involves stereospecific interaction with an intracellular vitamin D receptor (VDR). We recently found that retinoids, which are vitamin A derivatives, exert anticoagulant effects by upregulating thrombomodulin (TM) and downregulating tissue factor (TF) expression in acute promyelocytic leukemia cells and monoblastic leukemia cells. Both the VDR and retinoid receptors belong to the same family of receptors. A heterodimer consisting of the retinoid X receptor and the VDR binds to vitamin D responsive elements on genes regulated by vitamin D. To determine whether 1,25(OH)2D3 would exhibit anticoagulant effects similar to retinoids, we measured the antigen level, activity, and mRNA level of TM and TF in human leukemic cells, vascular endothelial cells, and monocytes treated with 1,25(OH)2D3. We found that 1,25(OH)2D3 upregulates antigen expression, activity, and mRNA levels of TM and downregulates antigen expression, activity, and mRNA levels of TF in human monocytic leukemia cells, some acute myelogenous leukemia cells, and monocytes, but not in umbilical vein endothelial cells. Transient transfection studies with reporter plasmids in monocytic leukemia cells and mobility gel-shift assay showed interaction with 1,25(OH)2D3 and functional retinoic acid responsive elements present in the 5'-flanking region of the TM gene. However, auxiliary factors or other elements in the TM gene may contribute to VDR specificity and transactivation of the gene in specific target cells. These findings indicate that 1,25(OH)2D3 resembles the retinoids in its control of the transcription of the TM and TF genes in human monocytic cells. Analogs of 1,25(OH)2D3 with anticoagulant activity may serve as adjunctive antithrombotic agents in monocytic leukemia and atherosclerotic disease.

Bone mineral density in patients undergoing bone marrow transplantation for myeloid malignancies

Bone mineral density (BMD) was measured in 23 patients who had undergone bone marrow transplantation (BMT) at the University of Minnesota for myeloid leukemia. The median age at BMT was 22 years (range 3-53) and the median age at assessment of BMD was 27 years (range 4-56). Total body BMD was measured a median of 2 years (range 1-10) after BMT using Dual Photon X-ray Absorptiometry (DEXA). BMD was measured in g/cm2, with results expressed as percent of normal values and as Z (standard deviation) scores. Patients were categorized into two groups (pediatric and adult) according to age at BMT (< or = 18 years vs > 18 years). Total body BMD of patients in the pediatric age group was significantly decreased (median Z-score -0.5) compared to the adult population (median Z-score 0.0, P = 0.03). No association was observed between BMD and time elapsed since BMT, type of conditioning regimen, gonadal function, steroid intake or graft-versus-host disease. Investigation of decreased BMD in children with AML following BMT is needed to determine the metabolic basis, long-term implications, appropriate preventive measures and potential interventions.

Pgp and MRP activities using calcein-AM are prognostic factors in adult acute myeloid leukemia patients

Thirteen cell lines with different levels of Pgp and MRP expression were used to assess the ability of calcein acetoxymethyl ester (calcein-AM) uptake and calcein efflux to measure Pgp and MRP functions, respectively. There was a good correlation between MRP expression and the modulatory effect of probenecid (a specific modulator of MRP) on the calcein efflux (r = .91, P = .0003) and between Pgp expression and the modulatory effect of CsA on calcein-AM uptake (r = .96, P < .0001). In light of the high correlations for both proteins, we tested calcein-AM uptake and efflux in fresh myeloid leukemic cells. In 53 acute myeloid leukemia (AML) patients, there was also a good correlation between MRP expression (measured by reverse transcription-polymerase chain reaction and by MRPm6 expression by flow cytometry) and the modulatory effect of probenecid on the calcein fluorescence (r = .92, P < .0001) and between Pgp expression as measured by UIC2 antibody binding on flow cytometry and the modulatory effect of cyclosporin A on calcein-AM uptake (r = .83, P < .0001). Pgp activity was higher in CD34+ leukemia than in CD34- leukemia (2.26 +/- 1.50 v 1.46 +/- 1.21, respectively; P = .003), and MRP activity was higher in CD34- leukemia than in CD34+ leukemia (1.77 +/- 0.40 v 1.4 +/- 0. 29, respectively; P = .004). Pgp expression and activity (P = .004 and P = .01, respectively) and MRP activity (P = .03) but not MRP expression were prognostic factors for achievement of complete remission. These results suggest that functional testing (with calcein-AM +/- modulators) for the presence of both MRP and Pgp activities is of prognostic value and that MRP contributes to drug resistance in AML.

A strong expression of CD44-6v correlates with shorter survival of patients with acute myeloid leukemia

CD44 is a ubiquitous cell-surface glycoprotein that displays many variant isoforms (CD44v) generated by alternative splicing of exons 2v to 10v. The expression of variant isoforms is highly restricted and correlated with specific processes, such as leukocyte activation and malignant transformation. We have herein studied CD44v expression in acute myeloid leukemia (AML) and, for comparison, in normal myelopoiesis. Protein expression of total CD44 and of CD44-3v, -6v, and -9v isoforms has been measured using specific monoclonal antibodies and flow cytometry. The composition of variant exon transcripts has been analyzed by semi-quantitative reverse transcriptase-polymerase chain reaction followed by Southern hybridization with exon-specific probes. Our data show that (1) CD44-6v isoforms are expressed on 12.0% +/- 2.5% of normal CD34(+) cells; this expression is sharply upregulated through monopoiesis and, inversely, downregulated during granulopoiesis. Also, CD44-3v and CD44-9v isoforms are detected on 10% and 14% of normal monocytes, respectively. (2) Sixty-nine from a total of 95 AML patients display a variable proportion (range, 5% to 80%) of CD44-6v+ leukemic cells. (3) A shorter overall survival characterizes the group of AML patients displaying more than 20% of CD44-6v+ leukemic cells (8 months v 18 months, P < .02). These data suggest, for the first time, that the protein expression of CD44-6v containing isoforms may serve as a new prognostic factor in AML.

Comparison of toxicity and outcome in patients with acute myeloid leukemia treated with high-dose cytosine arabinoside consolidation after induction with a regimen containing idarubicin or daunorubicin

The toxicity and outcome after high-dose ara-C/daunorubicin (HDara-C/DNR) consolidation therapy in de novo AML was compared in 11 patients who received an idarubicin-containing induction therapy (IDA; from June 1995 to March 1997) and 16 patients pretreated with daunorubicin (DNR; from July 1990 to May 1995) for induction. The DNR group consisted of two cohorts, one (n = 6) of patients who had received, as had the IDA group, two induction and one intermediate-dose ara-C consolidation courses, and another (n = 10) of patients who had been pretreated with one induction and one consolidation course prior to HDara-C/DNR. There was no difference in the relative dose between the three cohorts. Following HDara-C/DNR, the IDA-pretreated patients experienced a more prolonged myelosuppression during consolidation therapy compared with the DNR group. Duration of neutropenia (< 500 neutrophils/microl) following HDara-C/DNR was 31.2 +/- 16 days (mean +/- SEM) in the IDA group compared with 18.7 +/- 5 days in the DNR group (p < .001 Mann-Whitney U-test). The duration 'of thrombocytopenia (platelets < 25000/microl) was 34.8 +/- 20 days in the IDA group vs. 18.5 +/- 6 days in the DNR group (p < .005). The more prolonged myelosupression was associated with a longer duration of fever (18.9 +/- 24 vs. 6.9 +/- 5.2 days). A greater incidence, length (11 +/- 8 vs. 1.2 +/- 2 days), and severity of diarrhea were observed in the IDA-pretreated group. Three of 11 IDA patients experienced WHO grade III-IV diarrhea. In the IDA group two patients developed severe enterocolitis with Candida septicemia, and one of these patients died. One patient in the IDA group died during prolonged aplasia. In the DNR group 6/16 patients experienced grade I-II diarrhea. Two patients in each group died during consolidation therapy. The CR rate was 87% in the IDA group and 79% in the DNR group. Relapse-free survival after HDara-C is 50% at a median follow-up of 60 months in the DNR group and 45% after a median follow-up of 17 months in the IDA group. Whether the advantage of the superior response rate in the IDA-treated patients may be lost during HDara-C consolidation treatment due to increased toxicity remains to be proven in larger trials.

Distinctive demography, biology, and outcome of acute myeloid leukemia and myelodysplastic syndrome in children with Down syndrome: Children's Cancer Group Studies 2861 and 2891

In recent pediatric trials of acute myeloid leukemia (AML), children with Down syndrome (DS) have had significantly more megakaryoblastic leukemia and have experienced better outcome than other children. To further characterize AML in DS, Children's Cancer Group Studies 2861 and 2891 prospectively studied demography, biology, and response in AML and myelodysplastic syndrome (MDS) of children with and without DS. These studies evaluated timing of induction therapy and compared postremission chemotherapy with marrow transplantation in 1,206 children. One-hundred eighteen (9.8%) had DS, a fourfold increase in 20 years. DS patients were younger, had lower white blood cell and platelet counts, more antecedent MDS, acute megakaryoblastic leukemia or undifferentiated AML, and an under-representation of chromosomal translocations (P < .001 for each variable). Four-year event-free survival in DS was 69% versus 35% in others (P < .001). Intensively timed induction conferred significantly higher mortality in DS patients; bone marrow transplantation offered no advantage. Conventional induction followed by chemotherapy achieved an 88%, 4-year, disease-free survival in DS patients versus 42% in others (P < .001). Megakaryoblastic leukemia was unfavorable in others but prognostically neutral in DS. AML in DS is demographically and biologically distinct from AML in other children. It is singularly responsive to conventional chemotherapy and may warrant even less therapy. The increasing proportion of DS patients with AML most likely reflects changes in attitudes about entering DS patients on AML trials and possibly increasing ability to distinguish megakaryoblastic leukemia from lymphoid leukemia.

Clinical significance of granulocyte colony-stimulating factor (G-CSF) receptor expression in acute myeloid leukemia

We examined granulocyte colony-stimulating factor (G-CSF) receptor (GR) expression on leukemic cells from 44 adults with newly-diagnosed acute myeloid leukemia (AML). GR expression was higher in female patients. G-CSF was administered to AML patients after initial induction therapy without significant acceleration of leukemia, irrespective of GR expression level. G-CSF administration after initial chemotherapy did not adversely influence clinical outcome of GR-positive patients. However, at first relapse, leukemia regrowth was accelerated in 3 of 15 GR-positive patients who received G-CSF after re-induction. It remains to be determined whether leukemia acceleration due to G-CSF contributes to re-induction failure and if G-CSF therapy is a significant risk in relapsed, GR-positive AML patients.

Differences in CD14 and alpha-naphthyl acetate esterase positivity and relation to prognosis in AML

Alpha-naphthyl acetate esterase (ANAE) and CD14 expression, used for determination of monocytic cells, were compared and related to prognosis in 65 AML patients. Bone marrow aspiration material from AML patients has been used for the cytochemistry as well as flow cytometry. All non-erythroid cells have been included in the evaluation in both methods. 17/65 cases showed at least 15% difference between the proportion CD14 and ANAE positive cells. Cases with 20% or more CD14 positivity had poorer prognosis. For FAB classes M0-M3, presence of 10% or more CD14 was negative for overall survival (P = 0.01). ANAE did not show significant prognostic influence.

Levels of expression of CAF7 (CD98) have prognostic significance in adult acute leukemia

The levels of CD98 antigen expression were studied in 62 consecutive cases of adult acute leukemia including 24 acute lymphoblastic leukemia (ALL) and 38 acute myeloid leukemia (AML) using the monoclonal antibody CAF7 and flow cytometry. The mean follow-up was 13.5 months. The mean relative fluorescence intensity (MIF) of CAF7 varied between 6 and 83 channels (256 channels resolution). No correlation was established between CAF7 cell surface density and most of the predictive parameters such as age, sex, blood counts, immunophenotype, proliferative index (PI) or DNA index. Nevertheless expression of CAF7 correlated positively with survival duration (mean 210 vs 391 days, P = 0.048) and complete remission (CR) duration (mean 132 vs 361, days P = 0.032). The levels of CAF7 differed significantly between ALL and AML (P < 0.001), the ALL cases being all CAF7intermediate or CAF7high. In the AML group the low levels of CAF7 expression correlated with shorter CR duration (mean 132 vs 414 days, P = 0.017). The lack of correlation with other clinical and biological parameters suggested that CAF7 might have an independent prognostic significance in adult AML. Although PI was also positively related to survival duration (P = 0.02), it did not correlate with CR duration or the expression of CAF7. We suppose that the prognostic impact of CD98 is related to the control of cell growth and survival in which the molecule normally participates.