General information

Pentostatin (2′-deoxycoformycin) is a natural product isolated from Streptomyces antibioticus . It is a potent and irreversible inhibitor of adenosine deaminase, which is widely distributed in mammalian tissues, with particularly high constitutive activity in lymphocytes (T cells more than B cells). Pentostatin-related inhibition of adenosine deaminase results in accumulation of deoxyadenosine and its nucleotides, which in turn results in a negative regulatory effect on ribonucleotide reductase as well as DNA replication and repair. Proliferative lymphocytes are predominantly targeted by pentostatin and related compounds, which is of particular interest in the treatment of lymphoproliferative disorders.

Pentostatin has been used in the treatment of hairy-cell leukemia [ , ], B-cell chronic lymphocytic leukemia [ , ], T-cell leukemias and lymphomas [ , ], cutaneous lymphomas [ , ], Waldenstrom's macroglobulinemia [ ], and in glucocorticoid-refractory acute and chronic graft-versus-host disease [ , ].

Organs and systems

Nervous system

Inhibition of adenosine deaminase in the CSF can result in accumulation of adenosine and deoxyadenosine, which both have significant depressant effects in the nervous system, which may explain the increased incidence of lethargy during repeated cycles of pentostatin. In contrast, increasing the interval between doses reduces the incidence. Other nervous system adverse effects included depression, paresthesia, and mild drowsiness [ , ].

Electrolyte balance

Severe hyponatremia occurred 3 days after a first cycle of pentostatin therapy in a 27-year-old man with a cutaneous T-cell lymphoma; it was not clear if it was due to extrarenal sodium loss, or the syndrome of inappropriate antidiuretic hormone secretion, since there was evidence of both [ ].

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