Role of single-agent purine analogues in therapy of peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of lymphomas with different clinical presentation and morphologic, immunophenotypic, and cytogenetic markers. Many of these malignancies follow an aggressive course and current therapeutic strategies are limited. The prognosis for these patients is usually very poor. The purine analogues are a class of drugs that have been shown to be active in patients who have T-cell lymphoma. T cells have a very high concentration of adenosine deaminase (ADA), a key enzyme in the purine degradation pathway, which is blocked by this class of agent. Pentostatin has been the most extensively studied of these drugs in PTCL and has shown variable response rates. However, many of the reports are limited to small single-center studies. Larger prospective randomized trials will be necessary to examine this therapy and to further explore combination regimens, which may result in increased responses.