Avoiding peg-filgrastim (Peg-F) prophylaxis during the paclitaxel (T) portion of the dose-dense (DD) doxorubicin-cyclophosphamide (AC)-T regimen: A prospective study.

Abstract

517 Background: Use of growth factors (GF) adds considerable expense and some toxicity to adjuvant breast cancer chemotherapy. We tested the feasibility and safety of omitting routine GF use during the T portion of DD AC-T. Methods: This is a prospective, single-arm study in which patients (pts) who completed 4 cycles of DD-AC proceeded to DD-T 175 mg/m2 every two weeks (wks) without routine GF (NCT02698891). Key inclusion: age≤ 65, ECOG PS≤1, absolute neutrophil count (ANC) ≥1500/mm3, and no febrile neutropenia (FN) during DD-AC. Criteria to treat for T included ANC ≥1000/mm3. Peg-F was given only if pts had FN in a prior cycle, or at investigator discretion if infection or treatment delay > 1 wk. Once Peg-F was given, pts received it in all future cycles. The primary endpoint was the rate of T completion ≤ 7 wks from cycle 1 day 1 (C1D1) to C4D1. Secondary endpoints included total use of Peg-F, rates of hematologic toxicity and FN, reasons for dose modification or hold. If ≥85% of pts completed T on time, the regimen would be considered feasible. If the true on-time completion rate is 75%, the chance the regimen would be declared infeasible is 91%, and if it is 85% the chance that the regimen is falsely declared infeasible is 10% (power = 0.899). ≥100/125 pts had to complete T on time for the regimen to be deemed successful. Results: Among 127 pts enrolled, 125 received ≥1 dose of protocol therapy and are included in the analysis. Median age at registration was 46 (range 21-65). Median C1D1 ANC was 7500/mm3 (range 1500-20500). 112 (90%) (95% CI 83-94%) pts completed DD-T ≤ 7 wks, and 3 (2%) completed within > 7 wks (2 due to neutropenia); 10 (8%) did not complete all cycles of T. Omission of Peg-F was not causally related to non-completion of T in any pts. The most common reasons for dose reduction or delays were non-hematologic. One pt had FN but was able to complete T on time. Eight (6.4%) pts received Peg-F during the trial. Conclusions: Omission of routine GF use during DD-T according to a pre-specified algorithm appears safe, feasible, and was associated with a 95.7% reduction in use of Peg-F, relative to the current standard of care. Additional analyses including cost implications are ongoing. Clinical trial information: NCT02698891.