Single-agent rituximab in treatment-refractory or poor prognosis patients with chronic lymphocytic leukemia

Rituximab in combination with fludarabine and cyclophosphamide has significantly improved outcomes for patients with chronic lymphocytic leukemia (CLL) and an improvement in overall survival has recently been shown for the first time in the history of CLL treatment. However, the chemotherapy portion of this regimen may be unsuitable for elderly patients or those with significant comorbidities. We investigated the safety and tolerability of single-agent rituximab in 23 consecutive patients presenting with CLL at a single institution.

Patients received eight cycles of weekly rituximab (375 mg/m(2) initially). Patients progressing on rituximab treatment could receive up to five further courses of single-agent rituximab in escalating doses up to 3 gm/m(2) per dose. Previously untreated and previously treated patients, including those refractory to fludarabine, were eligible for the study.

Single-agent rituximab was efficacious, even in patients with treatment-refractory or poor-prognosis CLL. The overall response rate was 90.9% with a CR rate of 63.6%. The median PFS was 28.5 months, and median duration of response was 26 months. Responses were seen regardless of prior treatment including in patients refractory to fludarabine. Especially encouraging results were seen in patients receiving rituximab maintenance therapy who had a median duration of response substantially longer than those who did not receive maintenance (35 months vs. 14 months, respectively).

Rituximab was well tolerated with no unexpected adverse events even at the highest dose. These results indicate that single-agent rituximab is effective and has a place in the treatment of CLL.