Researchers from the MD Anderson Cancer Center have reported an 80% overall response rate following Rituxan® treatment for patients with hairy cell leukemia who have failed previous therapy. The results of this phase II clinical trial appeared in the December 2003 issue of Blood.

Hairy cell leukemia is a relatively rare, chronic B-cell lymphoproliferative disorder that responds to multiple therapies. However, few if any patients are cured. Hairy cells are made up of activated B-cells that co-express CD11c, CD19, CD20, CD22, CD25, and CD103. This is usually an indolent disease with neutropenia, anemia, thrombocytopenia, symptomatic splenomegaly, and constitutional symptoms. Patients are usually treated initially with cladribine (2-CdA, Leustatin®) which results in reported relapse-free survivals of 70-80% at 4-5 years. However, other treatments such as pentostatin (deoxycoformycin, Nipent®), interferon-alpha, splenectomy, and Rituxan® are also effective.

In the recent MD Anderson study, 15 patients who had relapsed following Leustatin® or Nipent® were treated with Rituxan®. They reported that 8 patients achieved a complete response and 4 a partial response. By 36 months, only 5 of the 12 responding patients had progressed. These authors suggested that Rituxan® should be explored in combination with Leustatin® or Nipent® as upfront therapy in an attempt to eradicate minimal residual disease.

Comments: Although hairy cell leukemia is a relatively rare disease, it has proven responsive to modern therapy with significant prolongation of survival in recent years. It appears that the addition of Rituxan® to current upfront therapies is of major interest in attempts to cure this disease.

Reference: Thomas DA, O’Brien S, Bueso-Ramos C, et al. Rituximab in Relapsed or Refractory Hairy Cell Leukemia. Blood 2003;102:3906-3911.