T-cell
malignancies are rare, making up 10% to 15% of all lymphoid
neoplasms in adults. They include many different types of disorders such as
T-cell prolymphocytic leukemia,
T-cell large granular lymphocytic leukemia,
adult T-cell leukemia/lymphoma,
cutaneous T-cell lymphoma, and
peripheral T-cell lymphoma, which are themselves divided into multiple subcategories. Most T-cell
malignancies arise as a result of
chromosomal abnormalities, including
T-cell receptor rearrangement anomalies.
Viral infections are implicated in the development of
adult T-cell leukemia/lymphoma and some cases of
peripheral T-cell lymphoma have been linked to Epstein-Barr virus or human immunodeficiency virus
infection. With the possible exception of
T-cell large granular lymphocytic leukemia, which often has an indolent course, T-cell
malignancies have not responded well to conventional chemotherapeutic treatment. The introduction of
monoclonal antibodies for the treatment of
cancer has changed the outlook for patients with T-cell
malignancies. Recent studies with single-agent
alemtuzumab, an anti-CD52
monoclonal antibody, have shown improved response rates and survival in patients with
T-cell prolymphocytic leukemia and
cutaneous T-cell lymphoma. Preliminary data also suggest that
alemtuzumab may have activity in patients with heavily pretreated
peripheral T-cell lymphoma who are refractory to conventional
chemotherapy. Preclinical studies with mice bearing human
adult T-cell leukemia/lymphoma cells suggest that
alemtuzumab may have a potential therapeutic role in this setting. Treatment of T-cell
hematologic malignancies with
alemtuzumab appears promising. Earlier treatment and combination with chemotherapeutic agents may improve treatment outcome for patients with these
malignancies and allow for consolidation with stem cell transplant strategies in selected patients.