[Survival in adults with acute lymphoblastic leukaemia]. / Overlevelse hos voksne med akutt lymfoblastisk leukemi.

BACKGROUND: The Norwegian treatment protocol for acute lymphoblastic leukaemia in adults was introduced in 1982 and has undergone minor changes thereafter. Earlier studies from The South Eastern Norway Regional Health Authority have reported 50 % five-year overall survival in patients treated according to this protocol. This article presents survival data for Norwegian adults with acute lymphoblastic leukaemia on a national basis. MATERIAL AND METHODS: Data for all patients between 15 and 65 years, who were diagnosed with acute lymphoblastic leukaemia in the period 2000-2007 according to The Norwegian Registry for Acute Leukaemia and Lymphoblastic Lymphoma, and were treated with chemotherapy with a curative intent were analysed for survival. RESULTS: 128 patients were diagnosed with acute lymphoblastic leukaemia in the study period. The overall remission rate was 85.9 %. Five-year survival was 49.2 % overall, 31.4 % for patients 40 years or older and 62.6 % for those younger than 40 years. INTERPRETATION: These results are in line with previous Norwegian studies and show a five- year overall survival which is more than 10 % higher than that reported in international multicenter studies. One explanation can be that the Norwegian treatment program is more intensive than most treatment protocols used in other countries.

Targeted therapy in acute myeloid leukaemia: current status and future directions.

BACKGROUND: The limit of acceptable toxicity for standard chemotherapeutic drugs used in acute myeloid leukaemia (AML) therapy has been reached. New therapeutic strategies are therefore needed. OBJECTIVE: This review summarizes development in new strategies, and gives an overview of the clinical status on new drugs for non-promyelocytic AML in adults. METHODS: Information was principally gathered from the databases ClinicalTrials.gov and PubMed.gov. RESULTS/CONCLUSION: The major improvements in AML treatment during the last two decades has not been the introduction of new therapeutic agents, but rather the more optimal use of well-known drugs (e.g., high-dose cytarabine therapy, the use of ATRA in maintenance therapy of acute promyelocytic leukaemia) and improvement in the diagnosis and treatment of potentially life-threatening complications in patients treated with allogeneic stem cell transplantation. However, further investigations based on specific targeted therapy and stratification of patients according to knowledge of the individual disease and health status will probably be necessary in future studies of new targeted therapy.

A subset of patients with high-risk acute myelogenous leukemia shows improved peripheral blood cell counts when treated with the combination of valproic acid, theophylline and all-trans retinoic acid.

Acute myelogenous leukemia (AML) patients (24 consecutive patients, median age 71 years, 17 high-risk disease) were treated with all-trans retinoic acid, theophylline and valproic acid. Among 22 evaluable patients 9 responded with increased normal peripheral blood cell counts. The responses could be classified as hematological improvement according to response criteria for patients with myelodysplastic syndromes (MDS) for four patients only. The nine patients with increased normal cell counts had a median survival from start of therapy of 147 days compared with 48 days for the other patients. Four patients fulfilling the MDS criteria had a survival ranging from 112 to 644 days. The treatment was associated with decreased in vitro cytokine-dependent AML cell proliferation and increased blood levels of Endocan and angiopoietin-2 both for responders and non-responders. We conclude that the therapy causes disease stabilization for a subset of AML patients.

In vivo biological effects of ATRA in the treatment of AML.

BACKGROUND: All-trans retinoic acid (ATRA) is mandatory in the treatment of acute promyelocytic leukaemia (APL). Experimental studies suggest that ATRA can induce differentiation and apoptosis in leukaemia cells also for other acute myelogenous leukaemia (AML) subtypes, but the clinical observations are conflicting. DESIGN AND METHODS: Twenty-two AML patients with non-APL disease received oral ATRA alone (22.5 mg/m2 twice daily) for two days, the patients thereafter continued ATRA together with valproic acid and theophylline. We investigated the biological effects of the initial 2 days treatment with ATRA alone. Serum/plasma samples were collected before and after 2 days of ATRA, peripheral blood AML cells were collected from all 12 patients with circulating leukaemia cells (ClinicalTrials.gov NCT00175812; EudraCT no. 2004-001663-22). RESULTS: AML cells collected during therapy had altered flow cytometric forward and right angle light scatters but no morphological signs of differentiation. ATRA increased the percentage of circulating AML cells in G0/G1 phase for 9 out of 12 patients (p = 0.043). Circulating leukaemia cells derived during therapy had increased intracellular levels of P21 (mean increase in mean fluorescence intensity (MFI) being 18.2%, p = 0.017), and decreased levels of Gata-2 (mean decrease in MFI 19%, p = 0.026), NF-kappaB p65 (mean decrease in MFI 15.4%, p = 0.033) and Bcl-2 (mean decrease in MFI 7.2%, p = 0.005). In addition, increased systemic levels of the endothelial marker endocan (plasma) and the angioregulatory mediator angiopoietin-2 (serum) were observed. CONCLUSIONS: In vivo ATRA treatment in AML affects leukaemic cell morphology, regulation of cell cycle progression and apoptosis, and possibly also microvascular endothelial cell functions.

Functional characteristics and gene expression profiles of primary acute myeloid leukaemia cells identify patient subgroups that differ in susceptibility to histone deacetylase inhibitors.

Modulation of gene expression through histone deacetylase (HDAC) inhibition is considered a possible therapeutic strategy in acute myeloid leukaemia (AML). In vitro effects and basal gene expression of structurally different HDAC inhibitors were examined. Primary human AML cells were derived from 59 consecutive patients. The HDAC inhibitors valproic acid, PXD101, trichostatin A and sodium butyrate inhibited leukaemic and clonogenic cell proliferation and increased apoptosis in a dose-dependent manner when tested at high concentrations. However, at lower concentrations proliferation increased for a subset of patients. This divergence was also observed in the presence of all-trans retinoic acid, theophylline and decitabine, and in cocultures with bone marrow stromal cells. Levels of IL-1beta, IL-6, GM-CSF and TNFalpha increased. Based on the basal expression of 100 genes the patients with growth enhancement at intermediate HDAC inhibitor concentrations and those without this response were clustered into two mutually exclusive groups. Functional characterization and gene expression analyses identify AML patient subsets that differ in their response to HDAC inhibitors. These observations may explain why HDAC inhibitor therapy affects only a subset of patients.

Clonogenic acute myelogenous leukemia cells are heterogeneous with regard to regulation of differentiation and effect of epigenetic pharmacological targeting.

Differentiation-inducing therapy with the DNA-methylation inhibitor Decitabine (5'-aza-deoxycytidine) and histone deacetylase (HDAC) inhibitors are now considered in acute myelogenous leukemia (AML). We investigated the in vitro effects of Decitabine and two structurally unrelated HDAC inhibitors (Sodium 4-phenyl butyrate, Tricostatin A) on clonogenic AML cells. Based on morphological criteria we identified four major colony types: (i) non-erythroid colonies, (ii) erythroid colonies that were detected only for a subset of patients and could be further sub classified into mature and immature forms, and (iii) intermediate colonies. Erythroid differentiation was associated with low CD34 expression. The colonies showed differences in morphology, viability, cell cycle distribution and expression of differentiation markers. Both Decitabine and the two HDAC inhibitors altered AML cell expression of differentiation markers, whereas the drugs did not have any major influence on cell cycle distribution. However, the pharmacological effects differed between the four colony subsets, and differences were also detected between the two HDAC inhibitors. We conclude that clonogenic AML cells can be classified into well-defined subsets based on their differentiation, and these subsets differ in their biological characteristics as well as their response to pharmacological targeting of epigenetic regulation.

The proteasome inhibitors bortezomib and PR-171 have antiproliferative and proapoptotic effects on primary human acute myeloid leukaemia cells.

Proteasome inhibitors represent a new class of antineoplastic drugs that are considered in the treatment of haematological malignancies. We compared the effects of the reversible proteasome inhibitor bortezomib (Velcade) and the epoxomicin derivative PR-171, an irreversible inhibitor, on primary human acute myeloid leukaemia (AML) cells. Both drugs inhibited autocrine- and cytokine-dependent proliferation of primary AML blasts when tested at nanomolar levels (0.1-100 nmol/l). The antiproliferative effect was independent of basal chymotrypsin-like proteasome activity (showing a 20-fold variation between patients), genetic abnormalities, morphological differentiation and CD34 expression when testing a large group of consecutive patients (n = 54). The effect was retained in cocultures with bone marrow stromal cells. In addition, both drugs enhanced apoptosis. The effect of PR-171 could be detected at lower concentrations than for bortezomib, especially when testing the influence on clonogenic AML cell proliferation. Both drugs had divergent effects on AML cells' constitutive cytokine release. Furthermore, both drugs caused a decrease in proliferation and viability when tested in combination with idarubicin or cytarabine. An antiproliferative effect on primary human acute lymphoblastic leukaemia cells was also detected. We conclude that nanomolar levels of the proteasome inhibitors tested had dose-dependent antiproliferative and proapoptotic effects on primary AML cells in vitro.

Protein lysine acetylation in normal and leukaemic haematopoiesis: HDACs as possible therapeutic targets in adult AML.

Several new therapeutic strategies are now considered for acute myelogenous leukaemia (AML), including modulation of protein lysine acetylation through inhibition of histone deacetylases (HDACs): a large group of enzymes that alters the acetylation and, thereby, the function of a wide range of nuclear and cytoplasmic proteins. Firstly, HDACs can deacetylate histones as well as transcription factors, and can modulate gene expression through both these mechanisms. Secondly, acetylation is an important post-translational modulation of several proteins involved in the regulation of cell proliferation, differentiation and apoptosis (e.g., p53, tubulin, heat-shock protein 90). The only HDAC inhibitors that have been investigated in clinical studies of AML are butyrate derivatives, valproic acid and depsipeptide. In the first studies, the drugs have usually been used as continuous therapy for several weeks or months, and in most studies the drugs were used alone or in combination with all-trans retinoic acid for treatment of patients with relapsed or primary resistant AML. Neurological toxicity and gastrointestinal side effects seem to be common for all three drugs. Complete haematological remission lasting for several months has been reported for a few patients (< 5% of included patients), whereas increased peripheral blood platelet counts seem more common and have been described both for patients with AML and myelodysplastic syndromes. Taken together, these studies suggest that HDAC inhibition can mediate antileukaemic effects in AML, but for most patients the clinical benefit seems limited and further studies of combination therapy are required.

A novel, extraneuronal role for cyclin-dependent protein kinase 5 (CDK5): modulation of cAMP-induced apoptosis in rat leukemia cells.

A number of cyclin-dependent protein kinase (CDK) inhibitors were tested for the ability to protect IPC-81 rat leukemic cells against cAMP-induced apoptosis. A near perfect proportionality was observed between inhibitor potency to protect against cAMP-induced apoptosis and to antagonize CDK5, and to a lesser extent, CDK2 and CDK1. Enforced expression of dominant negative CDK5 (but not CDK1-dn or CDK2-dn) protected against death, indicating that CDK5 activity was necessary for cAMP-induced apoptosis. The CDK inhibitors failed to protect the cells against daunorubicine-, staurosporine-, or okadaic acid-induced apoptosis. The inhibition of CDK5 prevented the cleavage of pro-caspase-3 in cAMP-treated cells. The cells could be saved closer to the moment of their onset of death by inhibitors of caspases than by inhibitors of CDK5. This suggested that the action of CDK5 was upstream of caspase activation. The cAMP treatment resulted in a moderate increase of the level of CDK5 mRNA and protein in IPC-81 wild-type cells. Such cAMP induction of CDK5 was not observed in cells expressing the inducible cAMP early repressor. The cAMP-induced increase of CDK5 contributed to apoptosis since cells overexpressing CDK5-wt were more sensitive for cAMP-induced death. These results demonstrate the first example of a proapoptotic CDK action upstream of caspase activation and of an extra-neuronal effect of CDK5.