Fludarabine/Cyclophosphamide/ Rituximab Combination Achieves High Molecular Remission Rate

HOUSTON-As treatments for chronic lymphocytic leukemia (CLL) improve, the definitions of complete remission (CR) and partial remission (PR) have become increasingly refined. The National Cancer Institute Working Group (NCIWG) also recognizes other types of responses, including nodular partial remission (nPR), defined as complete remission except for residual lymphocyte aggregates in bone marrow on biopsy. In addition, many CR patients have clonal disease detectable on flow cytometry and molecular remissions, defined as negative by polymerase chain reaction (PCR) for the IgVh gene. Because of the indolent, relapsing nature of CLL, there is interest in developing treatment regimens that have high molecular remission rates in the hope that achieving molecular remission may increase the duration of complete remission. Rituximab(Drug information on rituximab) (Rituxan) has been shown to improve the molecular remission rate after chemotherapy.[ 1] FCR Regimen A combination regimen of fludarabine (Fludara) (25 mg/m²/day for 3 days), cyclophosphamide(Drug information on cyclophosphamide) (Cytoxan, Neosar, 250 mg/m²/day for 3 days), and rituximab (375 to 500 mg/m² on day 1), the FCR regimen, was admin- istered to 135 previously untreated patients with CLL (ASH abstract 771).[2] Michael Keating, MD, and fellow investigators at the University of Texas M.D. Anderson Cancer Center, Houston, then compared the molecular remission rate to the NCI WG response criteria and clinical response. According to NCIWG criteria, response rates were: 67% CR, 19% nPR, and 18% PR. Of these, 9 responders have relapsed clinically and 12 patients have died: 2 with CR, 1 with nPR, 4 with PR, and 5 of the 7 nonresponders. The percentage of responding patients for each endpoint is summarized in Table 1.[2] In summary, FCR achieved high complete remission and molecular remission rates in patients with previously untreated CLL. The study suggests that molecular remission may correlate with good clinical prognosis.