HOUSTONThe combination of fludarabine (Fludara) and cyclophosphamide
(Cytoxan, Neosar) plus rituximab (Rituxan), known as FCR, produces "a
higher complete remission rate than prior regimens tested" against
chronic lymphocytic leukemia (CLL), reported William Wierda, MD, of the
department of leukemia at The University of Texas M. D. Anderson Cancer
Center in Houston. In addition, molecular remissions can be demonstrated in
a significant number of those responding to the FCR combination.
Among a group of 135 patients receiving six cycles of FCR, 63% of the
patients achieved complete remission and the overall response was 95%. To
determine the level of molecular remission, polymerase chain reaction (PCR)
assay was performed on the bone marrow of 55 of the 85 patients achieving
complete remission, and 56% were negative. Negativity was also demonstrated
in the bone marrow of 6 out of 10 partial responders assayed (out of a total
of 23). Five of those six patients were in partial remission due to anemia
or low platelet or neutrophil counts, and "none of the five had
morphologic evidence of residual disease," Dr. Wierda reported.
PCR was performed on both blood and marrow on some patients achieving
complete or partial remission. "There was a strong correlation between
blood and marrow," Dr. Wierda said, "and the discordance rate was
less than 10%."
Updated Data Presented
"The increased activity of fludarabine combined with
cyclosphosphamide, and the potential for chemosensitization between purine
analogs, alkylating agents, and monoclonal antibodies, is the rationale for
combining these agents in a trial to determine the efficacy." Dr.
Data presented on the FCR study last year included only 53 patients,
while the updated data include 135 patients. All were "required to have
an indication for treatment according to National Cancer Institute working
group criteria," Dr. Wierda said. In addition, patients could have had
no prior therapy for CLL, a performance status of 3 or less, and adequate hepatic
and renal function.
Six cycles of FCR were administered. In the first cycle, patients
received rituximab at the standard dose of 375 mg/m² on day 1. In subsequent
cycles, rituximab was administered at the higher dose of 500 mg/m² on day 1.
Fludarabine at 25 mg/m² and cyclophosphamide at 250 mg/m² were given on days
2 to 4 of cycle 1 and days 1 to 3 of cycles 2 to 6.