Dose-dense (DD) cyclophosphamide, methotrexate, and fluorouracil (CMF) at 14-day intervals: A pilot study of every 14- and 10–11-day dosing intervals for women with early-stage breast cancer
590 Background: CMF (C 600 mg/m2, M 40 mg/m2, F 600 mg/m2) is an option for adjuvant therapy for patients with low risk early stage breast cancer. DD regimens as predicted by mathematical models of cancer growth and treatment response are superior. We previously demonstrated the safety of DD EC (epirubicin/cyclophosphamide) followed by paclitaxel at 10–11 day (d) intervals. We investigated the feasibility of administering DD adjuvant CMF every 14 d and then every 10–11 d in a 2-stage phase II trial. Methods: An initial cohort (A) was treated q 14 d with PEG-filgrastim (Neulasta) support. A second cohort (B) was treated every 10–11 d with filgrastim/Neupogen x 5 d and then, based on feasibility, modified (cohort C) to use 7 d filgrastim. The primary end point was feasibility defined as having ANC > 1.5 x 103/uL on day 1 of planned treatment for all 8 cycles with no grade 3 or higher non-hematologic toxicity. All three cohorts were tested using a Simon's two-stage optimal design with type I and type II errors set at 10%. This design would effectively discriminate between true tolerability (as protocol-defined) rates of< 60% and> 80%. Cohort A: 38 pts with early stage breast cancer were accrued from 3/2008 though 6/2008. Cohort B: 7 pts were accrued from June 2008 through August 2008. Cohort C: Is still open with 16 pts accrued from August 2008 through December 5, 2008. Results: Median age 51: range 38 to 78. Cohort A: 29/38 pts completed 8 cycles of CMF. The regimen was considered feasible. 2 other pts completed 7 cycles and were withdrawn for depression and grade 2 transaminitis. The 7 other pts completed between 1 and 6 cycles of CMF were withdrawn as follows: 3 personal, 1 (grade 3) bone pain, 2 allergy unrelated to CMF, and 1 seizure. Cohort B: 7 pts were accrued. 6 out of 7 pts could not complete 8 cycles of chemotherapy secondary to neutropenia and 1 secondary to grade 3 ALT elevation. Cohort C: Accrual has not been completed. 16 pts are currently enrolled. Conclusions: Dose dense adjuvant CMF is feasible at 14 d intervals with PEG-filgrastim support. Adjuvant CMF every 10–11 days with filgrastim given for 5 days beginning day 2 is not feasible. Accrual is ongoing for CMF at 10–11 days with filgrastim x 7 days. Updated results will be available for Cohort C. [Table: see text]