Description
Pentostatin, an adenosine deaminase inhibitor, is an orphan drug introduced for the
treatment of hairy cell leukemia. The agent is considered a significant advance over
alpha-interferon, the only other drug available for this indication. The majority of
patients treated with pentostatin have been reported to remain in remission for at least
four years. It is also under investigation for the treatment of other kinds of leukemia
and in transplant rejection.
Description
Because of their antitumor activity
via inhibition of DNA synthesis, purine nucleoside derivatives resistant to deamination have been developed for the treatment of various leukemias. Pentostatin is a purine nucleoside analog that irreversibly inhibits adenosine deaminase (K
i = 0.9 pM) and thus interrupts DNA synthesis in dividing cells. Pentostatin has been reported to display strong efficacy in the clinical treatment of hairy cell leukemia as well as relapsed chronic lymphocytic leukemia.
Chemical Properties
White Solid
Originator
Warner-Lambert (Parke-Davis) (U.S.A.)
Uses
Pentostatin is a potent antitumor antibiotic isolated from a Streptomyces species. Pentostatin is a potent inhibitor of adenine deaminase and has been used therapeutically as an antitumor agent.
Uses
Pentostatin is a potent antitumour antibiotic isolated from a Streptomyces species. Pentostatin is a potent inhibitor of adenine deaminase and has been used therapeutically as an antitumour agent.
Uses
An adenosine deaminase inhibitor used as an anti-cancer therapeutic drug. Shown to be effective in the treatment of hairy cell leukemia as well as having use in the treatment of other types of cancer such as chronic lymphocytic leukemia.
Indications
Pentostatin (Nipent, deoxycoformycin) is a purine isolated
from fermentation cultures of the microbe
Streptomyces antibioticus. Its mechanism of action involves
inhibition of the enzyme adenosine deaminase,
which plays an important role in purine salvage pathways
and DNA synthesis.The resulting accumulation of
deoxyadenosine triphosphate (dATP) is highly toxic to
lymphocytes.
Pentostatin is effective in the therapy of hairy cell
leukemia, producing remissions in 80 to 90% of patients
and complete remissions in more than 50%. The major
toxic effects of the drug include myelosuppression, nausea,
and skin rashes.
brand name
Nipent (SuperGen),
Coforin (Katetsuken).
General Description
The drug is available in 10-mg vials for IV use. The drug isused to treat leukemias such as hairy cell leukemia, chroniclymphocytic leukemia, and lymphoblastic leukemia. Themechanism of action involves inhibition of the enzymeadenosine deaminase yielding increased cellular levels ofdeoxyadenosine and deoxyadenosine triphosphate (dATP).The increased levels of dATP are cytotoxic to lymphocytes.Pentostatin is a fermentation product of Streptomyces antibioticus.Resistance appears to involve decreased cellulartransport or increased expression of catabolic enzymes.Acid instability prevents oral administration, and the drug isonly administered by IV. The drug is distributed in totalbody water but does not enter the CNS. The majority of thedosage is excreted unchanged in the urine. Fatal pulmonary toxicity has occurred when pentostatin and fludarabine areused in combination. Toxicities include myelosuppression,immunosuppression, nausea, vomiting, headache, lethargy,and fatigue.
Biological Activity
Irreversible inhibitor of adenosine deaminase (K i = 2.5 pM). Anticancer agent.
Biochem/physiol Actions
Pentostatin/2′-deoxycoformycin is used to treat patients with Waldenstrm′s macroglobulinemia.
Mechanism of action
Pentostatin is the most potent inhibitor of adenosine deaminase, an important and ubiquitous cellular enzyme. Inhibition of this enzyme leads to the accumulation of dATP, which inhibits ribonucleotide reductase and thus DNA synthesis.
Clinical Use
Pentostatin is a ring-expanded purine ribonucleoside that inhibits adenosine deaminase and is
used in the treatment of hairy cell leukemia. The elevated levels of deoxyadenosine triphosphate that result
from inhibition of this degradative enzyme inhibit the action of ribonucleotide reductase (the enzyme that
converts ribose diphosphate to deoxyribose diphosphate), thus halting DNA synthesis within the tumor cell.
Safety Profile
Poison by intravenous route. An experimental teratogen. Human mutation data reported. When heated to decomposition it emits toxic fumes of NOx.
Synthesis
Under nitrogen atmosphere, 1.0 g of 3-((2R,4S,5R)-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-6,7-dihydroimidazo[4,5-d][1,3]diazepan-8(3H)-one was added to a reaction flask with 20 mg of RuCl (p-isopropyltoluene) [(R,R)-Ts-DPEN] catalyst. Subsequently, 10 mL of triethylamine and 3.3 mL of degassed formic acid were added to the reaction system. The reaction mixture was stirred at 40°C for 24 hours under nitrogen protection until high performance liquid chromatography (HPLC) monitoring showed a conversion of more than 99%. Upon completion of the reaction, the mixture was slowly poured into 200 ml of 100 mmol phosphate buffer pH 7.5. The product was purified by low-pressure reversed-phase column chromatography, resulting in 0.84 g (83% yield) of pure nebuletin with an 8R/8S isomer ratio of about 1000:1 as determined by HPLC.
Drug interactions
Potentially hazardous interactions with other drugs
Antipsychotics: avoid with clozapine (increased risk
of agranulocytosis).
Cytotoxics: increased risk of toxicity with high-dose
cyclophosphamide - avoid; increased pulmonary
toxicity with fludarabine (unacceptably high
incidence of fatalities).
Metabolism
Only a small amount is metabolised via the liver.
It is primarily excreted unchanged by the kidneys
(30-90% excreted by kidneys within 24 hours).
References
[1] Patent: TW2017/6283, 2017, A. Location in patent: Page/Page column 7; 8
