Impact of intracoronary injection of mononuclear bone marrow cells in acute myocardial infarction on left ventricular perfusion and function: a 6-month follow-up gated 99mTc-MIBI single-photon emission computed tomography study.

PURPOSE: We investigated the impact of intracoronary injection of autologous mononuclear bone marrow cells (BMC) in patients with acute ST elevation myocardial infarction (STEMI) on left ventricular volumes, global and regional systolic function and myocardial perfusion. METHODS: The study included 39 patients with first anterior STEMI treated successfully with primary percutaneous coronary intervention. They were randomly assigned to the treatment group or the control group in a 2:1 ratio. The patients underwent baseline gated single-photon emission computed tomography (G-SPECT) 3-10 days after STEMI with quantitative and qualitative analysis of left ventricular perfusion and systolic function. On the following day, patients from the BMC treatment group were subjected to bone marrow aspiration, mononuclear BMC isolation and intracoronary injection. No placebo procedure was performed in the control group. G-SPECT was repeated 6 months after STEMI. RESULTS: Baseline and follow-up G-SPECT studies were available for 36 patients. At 6 months in the BMC group we observed a significantly enhanced improvement in the mean extent of the perfusion defect, the left ventricular perfusion score index, the infarct area perfusion score and the infarct area wall motion score index compared to the control group (p = 0.01-0.04). However, the changes in left ventricular volume, ejection fraction and the left ventricular wall motion score index as well as the relative changes in the infarct area wall motion score index did not differ significantly between the groups. CONCLUSION: Intracoronary injection of autologous mononuclear BMC in patients with STEMI improves myocardial perfusion at 6 months. The benefit in infarct area systolic function is less pronounced and there is no apparent improvement of global left ventricular systolic function.

Clofarabine as a novel nucleoside analogue approved to treat patients with haematological malignancies: mechanism of action and clinical activity.

Clofarabine is a second generation of purine nucleoside analogues designed to combine the most favorable pharmacokinetic properties of fludarabine and cladribine. Clofarabine acts by inhibiting DNA polymerases and ribonucleotide reductase as well as by inducing apoptosis in cycling and non-cycling cells. Phase I/II clinical studies revealed its efficacy in hematological malignancies, and in 2004 clofarabine was approved by the United States Food and Drug Administration for the treatment of pediatric relapsed or refractory acute lymphoblastic leukemia after at least two prior chemotherapy regimens. The mechanism of action, pharmacology and clinical activity of clofarabine is the subject of this review.

Current status of older and new purine nucleoside analogues in the treatment of lymphoproliferative diseases.

For the past few years more and more new cytotoxic agents active in the treatment of hematological malignancies have been synthesized and become available for either in vitro studies or clinical trials. Among them the class of antineoplastic drugs belonging to the purine nucleoside analogues group (PNAs) plays an important role. Three of them: pentostatin (DCF), cladribine (2-CdA) and fludarabine (FA) were approved by Food and Drug Administration (FDA) for the treatment of hematological malignancies. Recently three novel PNAs: clofarabine (CAFdA), nelarabine (ara-G) and forodesine (immucillin H, BCX-1777) have been synthesized and introduced into preclinical studies and clinical trials. These agents seem to be useful mainly for the treatment of human T-cell proliferative disorders and they are currently undergoing clinical trials in lymphoid malignancies. However, there are also several studies suggesting the role of these drugs in B-cell malignancies. This review will summarize current knowledge concerning the mechanism of action, pharmacologic properties, clinical activity and toxicity of PNAs accepted for use in clinical practice, as well as new agents available for clinical trials.

The effects of intracoronary autologous mononuclear bone marrow cell transplantation on cardiac arrhythmia and heart rate variability.

BACKGROUND: The results of stem cell therapy after myocardial infarction (MI) have been conflicting. The effects of this therapy on ventricular arrhythmias and autonomic control of heart rate have not yet been established. AIM: To assess the effects of bone marrow cell (BMC) transplantation on the occurrence of arrhythmias and heart rate variability (HRV) parameters in short-term observation after ST-elevation myocardial infarction (STEMI). METHODS: Sixty patients with STEMI who underwent primary PCI, were randomly assigned to two groups: Group 1 - 36 patients selected for active treatment (autologous BMC, intracoronary injection mean 7 days after STEMI), and Group 2 - 24 control patients not treated with BMC transplantation. In all patients the infarct-related artery was the left anterior descending, and the left ventricular ejection fraction was < 40%. Two Holter sessions were performed: at baseline (HM1), on average 6 days after MI, and another one (HM2), 1 month after BMC implantation. From these recordings the frequency of non-sustained ventricular tachycardia (nsVT) episodes and the parameters of HRV were calculated. RESULTS: Both groups were comparable with regard to demographic data, the presence of risk factors and electrocardiographic parameters. In HM2 examination the frequency of nsVT tended to be higher in Group 1 (25 vs. 12.5%, NS). The HRV analysis showed lower HF and significant SDNN increase in the BMC group. In controls all the HRV parameters increased. The increase in HF was significantly lower in the BMC group than in controls (22.4 vs. 89.2 ms(2), p $lt 0.011). CONCLUSIONS: 1. During the first month after the intracoronary injection of BMC, non-significant increase of nsVT was observed. 2. The lack of significant increase in HF power after BMC infusion may be a sign of depressed parasympathetic tone.

Forodesine (BCX-1777, Immucillin H)--a new purine nucleoside analogue: mechanism of action and potential clinical application.

Recently a few new purine nucleoside analogues (PNA) have been synthesized and introduced into preclinical and clinical trials. The transition-state theory has led to the design of 9-deazanucleotide analogues that are purine nucleoside phosphorylase (PNP) inhibitors, termed immucillins. Among them the most promising results have been obtained with forodesine. Forodesine (BCX-1777, Immucillin H, 1-(9-deazahypoxanthin)-1,4-dideoxy-1,4-imino-D-ribitol) has carbon-carbon linkage between a cyclic amine moiety that replaces ribose and 9-deaza-hypixanthine. The drug is a novel T-cell selective immunosuppressive agent which in the presence of 2'-deoxyguanosine (dGuo) inhibits human lymphocyte proliferation activated by various agents such as interleukin-2 (IL-2), mixed lymphocyte reaction and phytohemagglutinin. In the mechanism of forodesine action two enzymes are involved: PNP and deoxycytidine kinase (dCK). PNP catalyzes the phosphorolysis of dGuo to guanine (Gu) and 2'-deoxyribose-1-phosphate, whereas dCK converts dGuo to deoxyguanosino-5'-monophosphate (dGMP) and finally to deoxyguanosino-5'-triphosphate (dGTP). The affinity of dGuo is higher for PNP than for dCK. Nevertheless, if PNP is blocked by forodesine, plasma dGuo is not cleaved to Gu, but instead it is intracellularly converted to dGTP by high dCK activity, which leads to inhibition of ribonucleotide reductase (RR), an enzyme required for DNA synthesis and cell replication, which eventually results in apoptosis. Forodesine is active in some experimental tumors in mice, however it could be used for the treatment of human T-cell proliferative disorders and it is undergoing phase II clinical trials for the treatment of T-cell non-Hodgkin's lymphoma, which includes cutaneous T-cell lymphoma (CTCL). Moreover, recent preclinical and clinical data showed activity of forodesine in B-cell acute lympholastic leukemia (ALL).

Depsipeptide (FK228) as a novel histone deacetylase inhibitor: mechanism of action and anticancer activity.

Depsipeptide (FK228), a new histone deacetylase inhibitor, has been recently introduced into clinical trials. This agent shows interesting metabolic properties, novel mechanism of action, and is undergoing phase I-II clinical studies in hematopoietic malignancies and solid tumors. Mechanism of action, pharmacokinetics and anticancer activity of depsipeptide is the subject of this review.

Purine nucleoside analogs as immunosuppressive and antineoplastic agents: mechanism of action and clinical activity.

The purine nucleoside analogs (PNA) form an important group of cytotoxic drugs active in the treatment of neoplastic and autoimmune diseases. Three of them, fludarabine (FA), cladribine (2-chlorodeoxyadenosine, 2-CdA) and pentostatin (2'-deoxycoformycin, DCF) have established clinical activity in hematological malignancies and have been approved by FDA. These drugs are also investigated in some autoimmune diosorders. Recently four novel PNA: clofarabine (CAFdA), nelarabine, immucillin H (BCX-1777, forodesine) and 8-chloroadenosine (8-Cl-Ado) have been synthesized and introduced into clinical trials. All these drugs have chemical structure similar to adenosine or guanosine, however, the mechanism of their action is different. FA, 2-CdA and CAFdA mainly require phosphorylation by deoxynucleoside salvage pathways. The cytotoxic effect exerts the triphosphate metabolites, which are incorporated into DNA, and finally lead to programmed cell death. In contrast, DCF does not need to be phosphorylated and results in an increase of plasma deoxyadenosine (dAdo) levels and intracellular deoxyadenosine triphosphate (dATP). Nelarabine is an arabinosylguanine (ara-G) prodrug, which after conversion to ara-G is phosphorylated to ara-G triphosphate (ara-GTP). Accumulation of ara-GTP finally leads to apoptosis. Forodesine is a purine nucleoside phosphatase (PNP) inhibitor which blocks intracellular deoxyguanine (dGuo) cleaving to guanine (Guo), but instead converts it to deoxyguanosine triphosphate (dGTP), and similarly to other PNA resulting in apoptosis. 8-chloroadenosine (8-Cl-Ado) is a ribonucleoside analog. The mechanism of its action is quite different from other PNA and remains poorly understood. However, it is known that the drug inhibits RNA synthesis, but not DNA. These agents have significant cytotoxic activity against lymphoid and myeloid malignant cells. Moreover, they have deleterious effects on the normal resting lymphocytes. They result in prolonged lymphocyte depletion especially in the CD4 subset of T-cells. Several clinical trials have demonstrated that PNA used alone or in combination with other cytotoxic drugs or monoclonal antibodies shows good efficacy and acceptable toxicity profile in the treatment of lymphoid malignancies. 2-CdA and DCF are drugs of choice in the treatment of hairy cell leukemia. FA and 2-CdA have significant clinical activity in low-grade non-Hodgkin's lymphoma and chronic lymphocytic leukemia. 2-CdA exhibits some activity in progressive multiple sclerosis and other autoimmune disorders. This review will summarize current knowledge concerning the mechanism of action, pharmacological properties, clinical activity and toxicity of PNA accepted for use in clinical practice as well as new agents available for clinical trials.

The influence of imatinib mesylate (STI571) used alone or in combination with purine nucleoside analogues on the normal and chronic myelogenous leukaemia progenitor cells in vitro.

Imatinib mesylate (STI571, Glivec), a signal transduction inhibitor used as a single agent demonstrates significant activity in patients with chronic myelogenous leukaemia (CML). Nevertheless, the interaction between STI571 and other antileukaemic drugs such as hydroxyurea, interferon alpha or cytarabine have also been investigated in order to further improve its effectiveness. In this study we have tried to answer the question if the combination of STI571 with purine nucleoside analogues (PNAs)- cladribine (2-CdA) and fludarabine (F-ara-A) intensifies the antiproliferative effect on granulocyte-macrophage progenitor cells (CFU-GM) from patients with CML as well as from normal persons. Our studies were based on the method of semisolid CFU-GM cultures in vitro. We added STI571 or PNAs singly to the culture, each of the drugs at three concentrations, as well as in combinations of the concentrations used. We showed that STI571 (0.5, 1.0 and 2.0 microM) used alone inhibited the colony growth of CML CFU-GM, as compared to CFU-GM derived from normal donors (p = 0.03; p = 0.0004; p = 0.0001). We also observed that STI571 used together with 2-CdA (5,10 and 20 microM) or F-ara-A (0.2, 0.4 and 0.8 microM) at all the combinations significantly inhibited the colony growth of CML CFU-GM, as compared either to the control or to STI571 used alone (p < 0.05). In addition, the differences between CML and normal CFU-GM colony growth inhibition after the use of the combination of the highest concentrations of STI571 either with 2-CdA or F-ara-A were statistically significant (p = 0.03 and p = 0.01, respectively). In conclusion, STI571 used together with both the PNAs had an additive effect on CML CFU-GM cells. However, further experimental and clinical studies concerning the usefulness of these combinations in the treatment of CML patients seem warranted.

Chronic myelomonocytic leukemia coexisting with B-cell chronic lymphocytic leukemia.

Coexistence of B-cell chronic lymphocytic leukemia (B-CLL) and chronic myelomonocytic leukemia (CMML) is an unusal event, and to our knowledge, only four such cases have been reported in the literature. We report a 68-year-old white woman in whom these two diseases were diagnosed concomitantly. The diagnosis was made on the basis of peripheral blood count, morphology and immunophenotyping, and bone marrow cytology and histology. Interphase FISH analysis detected a 13q14.3 deletion in lymphocytes nuclei and no such abnormality in monocytes nuclei. The PCR analysis of IgH gene rearrangement in the bone marrow, as well as the peripheral blood lymphocytes, showed two different monoclonal IgH configurations as the result of biallelic clonal rearrangement of IgH genes suggesting an origin of lymphocytes from B-cell progenitors. The patient was originally treated with prednisone 1 mg/kg/day because of progressive significant thrombocytopenia, without improvement. Subsequently, she received one course of cladribine (2-CdA). Significant reduction of lymphocytes in the peripheral blood was observed. However, rapid increase of monocytes was seen shortly after the 2-CdA treatment. Subsequently, she received hydroxyurea (1.5 g/day) without hematological improvement. The patient died in January 2003, three months after diagnosis because of progression of both leukemias and associated pneumonia. Possible etiopathogenic relationship between both disorders is discussed.

Hodgkin's type of Richter's syndrome in familial chronic lymphocytic leukemia treated with cladribine and cyclophosphamide.

Second malignancies are frequent complications in patients with chronic lymphocytic leukemia (CLL). Hodgkin's disease (HD) has been observed in approximately 0.5% of the patients with CLL and is known as Hodgkin's type Richter's syndrome (H-RS). We present a 64-year-old male patient with a familial history of CLL who developed H-RS in abdominal lymph nodes 6 years after CLL diagnosis and 18 months after treatment with cladribine (2-CdA) and cyclophosphamide. HD was diagnosed by fine needle aspiration. The disease was refractory to treatment with two courses of CHOP and three courses of ABVD chemotherapy. In the current literature we found case reports of only 6 patients with H-RS who were treated with fludarabine (FA) before transformation, and, to our knowledge the presented patient is the first to develop H-RS after treatment with 2-CdA combined with cyclophosphamide. He is also the first published patient with familial CLL in whom this complication developed.

Coexistence of chronic lymphocytic leukemia and essential thrombocythemia.

The association of chronic lymphocytic leukemia (CLL) with essential thrombocythemia (ET) is an extremely rare event and until now 3 patients with such coexistence have been reported in the literature. We report a 77-year-old white woman in whom these two disorders were diagnosed concomitantly on the basis of peripheral blood count and cytology, bone marrow cytology and histology, immunophenotyping, as well as exclusion criteria. The diagnosis of ET was also supported by spontaneous in-vitro erythroid colony growth and by evaluation of thrombopoietin (TPO) serum level. Interphase FISH analysis allowed to detect 13q14.3 deletion in 98% of lymphocytes nuclei. In contrast this aberration was not observed in the megakaryocytes. The results of PCR analysis of IgG gene rearrangement showed distinct bands characteristic for monoclonal lymphoid population in bone marrow, peripheral blood and inguinal lymph node. The patient was started on hydroxyurea 1 g/day and normalization of the platelet count was achieved. Possible etiopathogenic relationships between both disorders and differential diagnosis of ET and reactive thrombocytosis (RT) are discussed.

The effect of cyclosporin A used alone and in combination with either 2-chlorodeoxyadenosine or fludarabine on normal and chronic myelogenous leukemia progenitors in vitro.

We evaluated the influence of cyclosporin A (CsA) used alone or together with the new purine nucleoside analogues (PNAs) 2-chlorodeoxyadenosine (2-CdA) and fludarabine (F-ara-A) on the colony growth of normal and chronic myelogenous leukemia (CML) granulocyte-macrophage progenitor cells (CFU-GM) in cultures in vitro. The assay was based on the Iscove's method in our modification. Specimens of bone marrow were collected from 15 patients with CML in the chronic phase and from 10 hematologically normal patients. CsA at the concentrations of 1, 2 and 4 microg/ml was used alone and, at the concentration of 4 microg/ml, was preincubated with mononuclear cells (MNCs) and, after 30 min PNAs were added to the culture medium. Concentrations of 5, 10, and 20 nM 2-CdA and 0.4, 0.8 and 1.6 microM F-ara-A were used. After 14 days of incubation, the colonies were scored under an inverted microscope. We observed that CsA used alone at all three concentrations inhibited the colony growth of CML CFU-GM to a statistically significant degree compared with the control (p < 0.02) and that it did not significantly influence normal colony growth. The IC50 for CsA was 3.9 microg/ml in the case of normal CFU-GM and 2.7 microg/ml in the case of CML CFU-GM. After the use of CsA in combination with either the highest concentrations of 2-CdA or F-ara-A, statistically significant differences compared with CsA used alone were observed (p = 0.008, p = 0.03 for CsA with 2-CdA, and p = 0.0007, p = 0.005 for CsA with F-ara-A, respectively, for normal and CML CFU-GM). However, there were no significant differences between the combinations of drugs and PNAs used alone. In the case of the combination of CsA with the highest concentrations of both PNAs, significant differences in colony growth inhibition between normal and CML CFU-GM were observed (p = 0.002 and p = 0.005, respectively, for 2-CdA and F-ara-A). In conclusion, at the concentrations of the drugs used, a subadditive action was observed either between CsA and 2-CdA or between CsA and F-ara-A.

Effect of intracoronary injection of mononuclear bone marrow stem cells on left ventricular function in patients with acute myocardial infarction.

To investigate the effect of intracoronary injection of autologous mononuclear bone marrow stem cells (BMSCs) in patients with ST-elevation myocardial infarction (STEMI) on left ventricular (LV) systolic and diastolic function using standard echocardiography and 2-dimensional systolic strain. A total of 60 patients with first anterior wall STEMI and LV ejection fraction of <40%, treated with successful primary percutaneous coronary intervention were randomly assigned to the treatment group (BMSC group) or the control group in a 2:1 ratio. Transcatheter intracoronary injection of BMSCs into the infarct-related artery was performed 7 days after STEMI. Standard echocardiography and speckle tracking analysis was performed at baseline and 6 months after STEMI. No differences were found in the baseline echocardiographic parameters of LV systolic and diastolic dysfunction--the LV ejection fraction was 35 +/- 6% in the BMSC group, similar to that in the control group (33 +/- 7%, p = 0.42). After 6 months, the absolute change in the LV ejection fraction was significantly greater in the BMSC group than in the control group (10 +/- 9% versus 5 +/- 8%, p = 0.04). Significant improvement was seen in 2-dimensional systolic strain in all segments (12 +/- 4 vs 14 +/- 4; p = 0.0009) and in the infarcted area (5 +/- 2 vs 6 +/- 2; p = 0.0038) only in the BMSC group. Of the diastolic function parameters, we observed improvement in the early filling propagation velocity (30 +/- 8 cm/s vs 37 +/- 13 cm/s; p = 0.0008), early diastolic velocity - E' (4.5 +/- 1.5 vs 5.0 +/- 1.3, p = 0.02), and the E/E' ratio (17 +/- 7 vs 14 +/- 5; p = 0.03) in the BMSC group. In conclusion, intracoronary injection of unselected BMSCs in patients with STEMI improved both LV systolic and diastolic function at 6 months of follow-up.

Novel purine nucleoside analogues for hematological malignancies.

Recently, the search for more effective and safer antineoplastic agents has led to synthesis and introduction into preclinical and clinical studies of a few new purine nucleoside analogues (PNA). Three of them: clofarabine (CAFdA), nelarabine, and forodesine (immucillin H, BCX-1777), despite belonging to the same group of drugs such as PNA, have shown some differences concerning their active forms, metabolic properties and mechanism of action. However, all these drugs have demonstrated promising activity in patients with relapsed and refractory acute lymphoblastic leukemia (ALL). CAFdA was approved for the therapy of relapsed or refractory ALL in the third line of treatment. It has proved promising in pediatric patients as well as in some patients who are able to proceed to allogenic hematopietic stem cell transplantation (HSCT). Moreover, the drug exhibits an efficacy in acute myeloid leukemia (AML), blast crisis of chronic myelogenous leukemia (CML-BP) and myelodysplastic syndrome (MDS). Nelarabine is recommended for T-ALL and T-cell lymphoblastic lymphoma (T-LBL) with the overall response rates ranging from 11 to 60%. However, the use of the drug is limited by potentially severe neurotoxicity. Forodesine is a purine nucleoside phosphorylase (PNP) inhibitor and it has shown activity in relapsed and refractory T- and B-cells leukemias as well as in cutaneous T-cell lymphoma (CTCL). Recently patented, a few of inventions in the field of pharmaceutical preparation of new PNA have also been published. Great hopes are currently set on the use of these drugs in the treatment of lymphoid and myeloid malignancies in adult and in pediatric patients, however ongoing studies will help to define their role in the standard therapy.

Older and new formulations of cladribine. Pharmacology and clinical efficacy in hematological malignancies.

The purine nucleoside analog (PNA)--cladribine (2-CdA, 2-chlorodeoxyadenosine) is a cytotoxic agent of high efficacy in lymphoid and myeloid malignancies. This drug was approved by the FDA for treatment of hairy cell leukemia and in some European countries for treatment of refractory/relapsed chronic lymphocytic leukemia. 2-CdA is usually administered as continuous or intermittent intravenous infusion. Recently however, new formulations of this agent has been developed for subcutaneous and oral administration. In contrast to other PNA, 2-CdA is equally cytotoxic to both proliferating and quiescent cells and several pathways may be responsible for the mechanism of its action. In addition, recent data indicate that 2-CdA combined with other cytotoxic agents and monoclonal antibodies show synergistic proapoptotic and cytotoxic activity on lymphoid and myeloid neoplastic cells. This review article summarizes recent achievements in the understanding of 2-CdA mechanism of action, pharmacokinetics of different pharmaceutical formulations and its approved and possible future applications in the treatment of hematological malignancies. The most important recent patents concerning oral formulations of 2-CdA have been presented.

The influence of farnesyl protein transferase inhibitor R115777 (Zarnestra) alone and in combination with purine nucleoside analogs on acute myeloid leukemia progenitors in vitro.

R115777 (Tipifarnib, Zarnestra)-farnesyl transferase inhibitor belongs to the new class of signal transduction inhibitors which seems to be yielding results in the treatment of patients with solid tumors. Recently it has also been considered as a drug of promise in hematologic malignancies such as acute myeloid leukemia (AML), especially in older patients, in chronic myelogenous leukemia (CML) as well as myelodysplastic syndromes (MDS). The aim of our study was to evaluate the influence of R115777 used alone or with purine nucleoside analogs (PNA): cladribine (2-CdA) and fludarabine (F-ara-A) on leukemic progenitors [colony-forming unit-leukemia (CFU)-L] from AML patients. Our studies were based on the methods of semisolid leukemic CFU-L and normal granulocyte-macrophage progenitor (CFU-GM) cultures in vitro. R115777 was added to the culture alone or in combinations with PNA. We showed that R115777 used alone or together with PNA at all combinations significantly inhibited the colony growth of AML CFU-L, when compared with normal CFU-GM (P < 0.01). In addition, the drugs used in combinations of two higher concentrations in significantly higher degree inhibited CFU-L colony growth, when compared either with R115777 or with any of PNA used alone (P < 0.04). IC(50) for R115777 were 67.1 and 121.9 nm for AML CFU-L and normal CFU-GM, respectively. Furthermore, in the case of AML the combination index was 0.89 and 1.16, respectively, for the combination of R115777 with 2-CdA and R115777 with F-ara-A. An additive effect on AML CFU-L cells and subadditive effect on normal CFU-GM were seen. To assess a proapoptotic effect, the drugs were added to the liquid cultures at the same concentrations as for clonogenic assays. A significant increase in the rate of apoptosis induced by combinations of drugs in comparison with single agents was observed. In conclusion, the combination of R115777 with both PNA could be more effective than the drugs used alone. However, further experimental studies on the usefulness of these combinations in the treatment of myeloid leukemia patients are warranted.