Adenosine deaminase (Ki = 2.5 pM)

The aim of this study was to evaluate the anti-trypanosomal effect of treatment with 3'-deoxyadenosine (cordycepin) combined with deoxycoformycin (pentostatin: inhibitor of the enzyme adenosine deaminase) in vitro by using mice experimentally infected with Trypanosoma evansi. In vitro, a dose-dependent trypanocidal effect of cordycepin was observed against the parasite[2].

Pentostatin (2 mg/kg) combined with cordycepin (2 mg/kg) was 100% effective against Trypanosoma evansi-infected mice. Increased levels of some biochemical parameters, especially liver enzymes, were accompanied by histological lesions of the liver and kidneys. Pentostatin alone has no effect on infected groups. All dogs developed granulocytopenia with granulocyte counts <500 cells/μL starting on day 4. Thrombocytopenia (<20,000 platelets/μL) begins on day 7 after HCT, with a nadir of 3000 to 14000 platelets/μL [1].

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In the in vivo trials, the two drugs were used individually and in combination of different doses. The drugs when used individually had no curative effect on infected mice. However, the combination of cordycepin (2 mg kg-1) and pentostatin (2 mg kg-1) was 100% effective in the T. evansi-infected groups. There was an increase in levels of some biochemical parameters, especially on liver enzymes, which were accompanied by histological lesions in the liver and kidneys. Based on these results we conclude that treatment using the combination of 3'-deoxyadenosine with deoxycoformycin has a curative effect on mice infected with T. evansi. However, the therapeutic protocol tested led to liver and kidney damage, manifested by hepatotoxicity and nephrotoxicity[2].

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Extracorporeal photopheresis (ECP) and the purine analog pentostatin exert potent immunomodulatory effects. We evaluated the use of these treatment modalities to prevent GVHD in a canine model of unrelated dog leukocyte Ag-mismatched hematopoietic cell transplantation, after conditioning with 920 cGy TBI. We have shown previously in this model that 36/40 dogs given MTX alone as postgrafting immunosuppression engrafted and that 25 of 40 dogs had severe GVHD and median survival of 21 days. In the current study, nine dogs received conditioning with 920 cGy TBI and postgrafting MTX either with ECP on days -2 to -1 alone (n=5) or ECP on days -6 and -5 combined with two doses of pentostatin (days -4 to -3) (n=4). Seven of nine dogs achieved engraftment. Six dogs developed severe acute GVHD (four in the group with ECP alone and two with pentostatin and ECP). We failed to demonstrate a positive impact of ECP and pentostatin for the prevention of GVHD compared with historical control dogs.[1]

DLA-nonidentical marrow grafts [1]
All recipient dogs were conditioned for transplantation by 920 cGy TBI at 7 cGy/minute using a linear accelerator. Dogs in group A1 received ECP administered on days −2 and −1 with TBI on day 0 and dogs in group A2 received ECP on days −6 and −5, intravenous (IV) infusion of pentostatin at a dose of 4mg/m2 on days −4 and −3, and TBI on day 0 (Table 1). Donor marrow cells from DLA-nonidentical donors were aspirated under general anesthesia through needles inserted into humeri and femora and stored in heparinized tissue culture medium at 4°C for no more than 6 hours.22 Within 4 hours of TBI, harvested marrow cells were infused IV into recipients at a median dose of 2.9 (range, 1.9 to 6.1) ×108 total nucleated cells (TNC)/kg. The day of marrow grafting was designated as day 0. In addition to marrow graft, recipients were given IV infusions of peripheral blood buffy coat cells obtained by leukapheresis from the marrow donor on days 1 and 2, at a median dose of 2.3 (range, 1.2 to 6.9) ×108 TNC/kg to ensure consistent hematopoietic engraftment. MTX, at a dose of 0.4 mg/kg intravenously was used as postgrafting immunosuppression and administered on days +1, +3, +6 and +11, then weekly thereafter until day 102.

[1]. Bethge WA, et al. Extracorporeal photopheresis combined with pentostatin in the conditioning regimen for canine hematopoietic cell transplantation does not prevent GVHD. Bone Marrow Transplant. 2014 Sep;49(9):1198-204.
[2]. Dalla Rosa L, et al. Cordycepin (3'-deoxyadenosine) pentostatin (deoxycoformycin) combination treatment of mice experimentally infected with Trypanosoma evansi. Parasitology. 2013 Apr;140(5):663-71

Pentostatin is a member of the class of coformycins that is coformycin in which the hydroxy group at position 2' is replaced with a hydrogen. It is a drug used for the treatment of hairy cell leukaemia. It has a role as an EC 3.5.4.4 (adenosine deaminase) inhibitor, an antineoplastic agent, an antimetabolite, a bacterial metabolite and an Aspergillus metabolite. It is a conjugate base of a pentostatin(1+).

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A potent inhibitor of adenosine deaminase. The drug is effective in the treatment of many lymphoproliferative malignancies, particularly hairy-cell leukemia. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity.
Pentostatin is a Nucleoside Metabolic Inhibitor. The mechanism of action of pentostatin is as a Nucleic Acid Synthesis Inhibitor.
Pentostatin is a purine analogue and antineoplastic agent used in the therapy of hairy cell leukemia and T cell lymphomas. Pentostatin is associated with a low rate of serum enzyme elevations during therapy and has been linked to rare instances of severe acute liver injury with jaundice.

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Pentostatin is a natural product found in Streptomyces antibioticus with data available.
Pentostatin is a purine nucleotide analogue antibiotic isolated from the bacterium Streptomyces antibioticus. Also known as 2'-deoxycoformycin, pentostatin binds to and inhibits adenine deaminase (ADA), an enzyme essential to purine metabolism; ADA activity is greatest in cells of the lymphoid system with T-cells having higher activity than B-cells and T-cell malignancies higher ADA activity than B-cell malignancies. Pentostatin inhibition of ADA appears to result in elevated intracellular levels of dATP which may block DNA synthesis through the inhibition of ribonucleotide reductase. This agent may also inhibit RNA synthesis and may selectively deplete CD26+ lymphocytes. (NCI04)

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Pentostatin can cause developmental toxicity according to state or federal government labeling requirements.
Pentostatin is only found in individuals that have used or taken this drug. It is a potent inhibitor of adenosine deaminase. The drug is effective in the treatment of many lymphoproliferative malignancies, particularly hairy-cell leukemia. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity. Pentostatin is a potent transition state inhibitor of adenosine deaminase (ADA), the greatest activity of which is found in cells of the lymphoid system. T-cells have higher ADA activity than B-cells, and T-cell malignancies have higher activity than B-cell malignancies. The cytotoxicity that results from prevention of catabolism of adenosine or deoxyadenosine is thought to be due to elevated intracellular levels of dATP, which can block DNA synthesis through inhibition of ribonucleotide reductase. Intracellular activation results in incorporation into DNA as a false purine base. An additional cytotoxic effect is related to its incorporation into RNA. Cytotoxicity is cell cycle phase-specific (S-phase).
A potent inhibitor of ADENOSINE DEAMINASE. The drug induces APOPTOSIS of LYMPHOCYTES, and is used in the treatment of many lymphoproliferative malignancies, particularly HAIRY CELL LEUKEMIA. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity.

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Drug Indication
For the treatment of hairy cell leukaemia refractory to alpha interferon.

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LiverTox Summary
Pentostatin is a purine analogue and antineoplastic agent used in the therapy of hairy cell leukemia and T cell lymphomas. Pentostatin is associated with a low rate of serum enzyme elevations during therapy and has been linked to rare instances of severe acute liver injury with jaundice.

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Pentostatin is used for the palliative treatment of hairy cell leukemia (leukemic reticuloendotheliosis) that responds inadequately to, or progresses during, interferon alfa therapy. Pentostatin has been designated an orphan drug by the US Food and Drug Administration (FDA) for the treatment of this condition. ... Pentostatin produces clinically important tumor regression or disease stabilization (complete or partial responses) in approximately 80-100% of patients with hairy cell leukemia, including in previously untreated patients (eg, those who have not undergone splenectomy or other therapy) as well as in those in whom splenectomy and/or therapy with other agents (eg, interferons, antineoplastic agents) have failed to control the disease (eg, those with progressive disease). In clinical studies in patients with interferon alfa-refractory hairy cell leukemia, a complete response to pentostatin therapy generally was defined as clearing of peripheral blood and bone marrow of hairy cells; normalization of organomegaly and lymphadenopathy; and recovery of hemoglobin concentration to at least 12 g/dl, platelet count to at least 100,000/cu mm, and granulocyte count to at least 1500/cu mm. A partial response was defined as a decrease of greater than 50% in the number of hairy cells in peripheral blood and bone marrow and a decrease of greater than 50% in organomegaly and lymphadenopathy; hematologic parameters for a partial response were the same as those for a complete response. Overall complete and partial responses of 58 and 28%, respectively, reportedly were observed in a limited number of these patients receiving pentostatin 4 mg/sq m iv every other week for 3 mo; responding patients continued treatment for another 3-9 mos. The median time to response in these patients reportedly was 4.7 mo (range: 2.9-24.1 mo). The median duration of response to pentostatin therapy in 2 clinical studies of patients with hairy cell leukemia reportedly exceeded 7.7 and 15.2 mo, with relapse occurring in approximately 15-20% of patients showing an initial response. For patients with progressive, postsplenectomy disease, pentostatin generally has been considered an alternative to interferon alfa or secondary therapy for interferon refractory disease since experience with interferon alfa has been more extensive to date. However, superiority of either drug or of other therapies remains to be established.

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Pentostatin is a toxic drug with a low therapeutic index, and a therapeutic response is not likely to occur without some evidence of toxicity. The drug must be used only under constant supervision by physicians experienced in therapy with cytotoxic agents. Most, but not all, adverse effects of pentostatin are reversible if detected promptly. When severe adverse effects occur during pentostatin therapy, the drug should be discontinued or dosage reduced and appropriate measures instituted. Pentostatin should be reinstituted with caution if at all, with adequate consideration of further need for the drug, and with awareness of possible recurrence of toxicity.

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Pharmacodynamics
Pentostatin is an antineoplastic anti-metabolite used in the treatment of several forms of leukemia including acute nonlymphocytic leukemia and hairy cell leukemia. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (of the cell cycle), stopping normal development and division. It is a 6-thiopurine analogue of the naturally occurring purine bases hypoxanthine and guanine. Intracellular activation results in incorporation into DNA as a false purine base. An additional cytotoxic effect is related to its incorporation into RNA. Cytotoxicity is cell cycle phase-specific (S-phase).

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Absorption
Not absorbed orally, crosses blood brain barrier. Route of Elimination
In man, following a single dose of 4 mg/m2 of pentostatin infused over 5 minutes, approximately 90% of the dose was excreted in the urine as unchanged pentostatin and/or metabolites as measured by adenosine deaminase inhibitory activity.
Clearance
68 mL/min/m2
Plasma concentrations of pentostatin following direct iv injection of 0.25 mg/kg daily for 4 or 5 days in a limited number of patients with advanced, refractory cancer ranged from approximately 3.2-9.7 ng/ml. Plasma concentrations appear to increase linearly with dose; in a study in patients with leukemia, plasma pentostatin concentrations determined 1 hour after administration of 0.25 or 1 mg/kg of the drug as a 30 min iv infusion averaged approximately 0.4 or 1.26 ug/ml, respectively.

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Metabolism / Metabolites
Primarily hepatic, but only small amounts are metabolized. DrugBank Primarily hepatic, but only small amounts are metabolized. Route of Elimination: In man, following a single dose of 4 mg/m2 of pentostatin infused over 5 minutes, approximately 90% of the dose was excreted in the urine as unchanged pentostatin and/or metabolites as measured by adenosine deaminase inhibitory activity. Half Life: 5.7 hours (with a range between 2.6 and 16 hrs)

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Biological Half-Life
hours (with a range between 2.6 and 16 hrs)
Following iv administration of 4 mg/sq m of pentostatin as a single dose over 5 min in healthy individuals, the distribution half-life and terminal elimination half-life reportedly averaged 11 min and 5.7 hr, respectively. In a multiple dose study in a limited number of patients receiving 36 courses of pentostatin at a dosage of 4 mg/sq m iv, distribution half-life and terminal elimination half-life reportedly averaged 9.6 min (range: 3.1-48.5 min) and 4.9 hr, respectively. In other studies in a limited number of patients with advanced cancer, the distribution half-life averaged 17-85 min and the terminal elimination half-life averaged 2.6-15 hr following single iv doses of 0.1 or 0.25 mg/kg of pentostatin.

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Mechanism of Action
Pentostatin is a potent transition state inhibitor of adenosine deaminase (ADA), the greatest activity of which is found in cells of the lymphoid system. T-cells have higher ADA activity than B-cells, and T-cell malignancies have higher activity than B-cell malignancies. The cytotoxicity that results from prevention of catabolism of adenosine or deoxyadenosine is thought to be due to elevated intracellular levels of dATP, which can block DNA synthesis through inhibition of ribonucleotide reductase. Intracellular activation results in incorporation into DNA as a false purine base. An additional cytotoxic effect is related to its incorporation into RNA. Cytotoxicity is cell cycle phase-specific (S-phase).

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The precise mechanism(s) of action of pentostatin in hairy cell leukemia and other lymphoid malignancies has not been fully elucidated. Pentostatin is a potent transition state (tight binding) inhibitor of adenosine deaminase, an enzyme involved in purine metabolism. This enzyme appears to regulate intracellular adenosine concentrations via irreversible deamination of adenosine and deoxyadenosine. Although adenosine deaminase is widely distributed in mammalian tissues, highest levels are found in lymphoid tissue: levels in circulating T cells (particularly in T cell lymphoblastic leukemia) are higher than those in B cells. While the level of enzyme activity is low in healthy bone marrow, it is high in myeloid leukemic blast cells. ... Inhibition of adenosine deaminase by pentostatin results in intracellular accumulation of toxic levels of adenine deoxynucleotides (eg, deoxyadenosine triphosphate), which in the presence of deoxyadenosine can lead to cell death. Pentostatin alone, even in concentrations high enough to inhibit adenosine deaminase completely, is not cytotoxic to lymphoid cells cultured in the absence of cytotoxic nucleosides (eg, deoxyadenosine). Thus, unlike many other nucleoside-analog antineoplastic agents, the cytoxic effects of pentostatin do not appear to be attributable directly to the drug or its metabolites but instead appear to result indirectly from the effects of the substrates for adenosine deaminase (adenosine and deoxyadenosine) and/or their metabolites. Although elevated deoxyadenosine triphosphate concentrations in the cell can block DNA synthesis via inhibition of ribonucleotide reductase, the precise role of high deoxyadenosine triphosphate concentrations in pentostatin-induced cytotoxicity is controversial. Pentostatin also can inhibit RNA synthesis, cause DNA strand breaks, disrupt ATP-dependent cellular processes, and inhibit adenosylhomocysteinase (S-adenosylhomocysteine hydrolase), all of which also may contribute to the drug's lymphocytotoxic effects. McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 93. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1993 (Plus Supplements, 1993)., p. 633
The degree to which pentostatin inhibits adenosine deaminase varies among cell types, possibly because of differences in enzyme inhibitor dissociation constants in different cells as well as differences in cellular accumulation of the drug. There generally has been no clear relation between adenosine deaminase inhibition and pentostatin induced cytotoxicity in clinical studies. However, the cytotoxic and growth inhibitory effects of adenosine deaminase inhibition appear to be greater in T cells than in B cells. Although conflicting data exist, some evidence suggests that T cells accumulate more deoxyadenosine triphosphate than B cells and thus may be more susceptible to the effects of adenosine deaminase inhibition; deoxyadenosine triphosphate concentrations in B cells may be lower because these cells possess higher membrane associated ecto-5'-nucleotidase activity, which promotes the hydrolysis of higher phosphate compounds to more freely diffusible nucleosides. Differences in the sensitivity of B and T cells to pentostatin's effects also may be artifactual as a result of testing procedure variables (eg, cell source, culture media conditions). The time course of adenosine deaminase inhibition appears to differ in erythrocytes and lymphocytes and depends on the intrinsic activity of the enzyme in the cell as well as cell specific pharmacodynamics (eg, protein synthesis, rate of cellular proliferation). In some cells, inhibition by a single dose of pentostatin may persist for 1 week or longer. It is not known whether recovery from adenosine deaminase inhibition occurs as a result of slow efflux of pentostatin from the cell or regeneration of adenosine deaminase; however, recovery of blood adenosine deaminase activity may result from replenishment of enzyme from newly formed erythrocytes in that such recovery in animals has been reported to coincide with the life span of erythrocytes in circulation (eg, 40-60 days). ... Response to pentostatin varies according to the type and sensitivity of the neoplasm being treated. Conditions associated with relatively low adenosine deaminase activity (eg, hairy cell and chronic lymphocytic leukemias) manifest prolonged and complete adenosine deaminase inhibition in response to relatively low dosages of pentostatin, whereas conditions associated with high adenosine deaminase activity (eg, acute leukemias) are less sensitive to the drug, requiring higher doses that produce relatively incomplete inhibition of adenosine deaminase activity. McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 93. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1993 (Plus Supplements, 1993)., p. 633

C11H16N4O4

268.2691

268.117

C, 49.25; H, 6.01; N, 20.88; O, 23.86

53910-25-1

439693

Typically exists as White to off-white solids at room temperature

1.8±0.1 g/cm3

673.1±65.0 °C at 760 mmHg

220-225ºC

360.9±34.3 °C

0.0±2.2 mmHg at 25°C

1.793

-2.16

O1[C@]([H])(C([H])([H])O[H])[C@]([H])(C([H])([H])[C@]1([H])N1C([H])=NC2[C@@]([H])(C([H])([H])N=C([H])N([H])C1=2)O[H])O[H]

FPVKHBSQESCIEP-KDXUFGMBSA-N

InChI=1S/C11H16N4O4/c16-3-8-6(17)1-9(19-8)15-5-14-10-7(18)2-12-4-13-11(10)15/h4-9,16-18H,1-3H2,(H,12,13)/t6-,7+,8+,9-/m0/s1

(R)-3-((2S,4S,5R)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-3,6,7,8-tetrahydroimidazo[4,5-d][1,3]diazepin-8-ol

Deoxycoformycin; CI825; CI-825; Deoxycoformycin; Nipent; 53910-25-1; 2'-Deoxycoformycin; PD-ADI; Pentostatina; Pentostatine; CI 825; PD81565; PD-81565; PD 81565; covidarabine; deoxycoformycin; pentostatine. brand name: Nipent.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~100 mg/mL (~372.76 mM)
DMSO : ≥ 50 mg/mL (~186.38 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (7.75 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (7.75 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (7.75 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)