Peripheral T-cell lymphomas: diagnosis and management.

Peripheral T-cell lymphomas are a diverse group of diseases with varying clinical manifestations. Response to conventional chemotherapy generally is poor. Treatment using purine analogs has achieved response rates between 25% and 60% in relapsed/refractory patients, with minimal toxicity. The highest response rates were seen with pentostatin and gemcitabine. Using purine analogs in combination therapy may improve response rates, albeit with an increased risk of toxicity. The role of purine analogs as first line therapy in patients who have otherwise favorable prognostic factors has not been defined. Monoclonal antibody therapy has emerged in the last decade as a promising approach in treating T-cell malignancies. Campath-1H is an effective and well-tolerated therapy in these diseases. Durable remissions have been seen in heavily pretreated patients and in up to two thirds of patients who had T-PLL, which is the largest disease group studied. These results in T-PLL are significantly better than those reported with other therapies; this suggests that Campath-1H should be moved to first line therapy in this aggressive disease. The way in which monoclonal antibodies work indicate that they may be particularly useful in treating patients who have minimal residual disease, and, in this setting, facilitate stem cell transplantation. In addition, the activity of Campath-1H to deplete T cells has been exploited in preparative regimens before allogeneic bone marrow transplantation. These approaches may be worth further investigation in patients who have T-cell lymphomas. None of the therapies that are available to treat the mature T-cell neoplasms seems to be curative, other than in selected patients who have favorable ALCL. Much of the data have been drawn from small, non-randomized studies. There is a need for larger, prospective, randomized trials to examine these novel therapies and to further explore combination regimens, which may exploit potential synergism.