Primary prophylaxis of febrile neutropenia using long-acting granulocyte colony-stimulating factors in female patients receiving dose-dense biweekly chemotherapy in the clinical routine.

e20693 Background: Dose-dense q2w chemotherapy (ddCtx) which gains increasing importance in the treatment of breast (BC) and other gynecologic cancers (GC) requires primary prophylaxis (PP) with granulocyte colony-stimulating factors (G-CSFs) to prevent febrile neutropenia (FN). This retrospective analysis was initiated to yield detailed information on the use of long-acting (LA) G-CSFs as FN PP in the clinical routine. Methods: 53 pts with BC or GC were included, 27 received pegfilgrastim (cohort P), and 26 received lipegfilgrastim (cohort L). Both cohorts were well balanced in terms of tumor types and the proportion of pts with metastatic disease. In all pts, 1-4 ddCtx cycles (C) were evaluated. G-CSF-related toxicities were scored according to CTCAE 4.03. Hematological efficacy was determined by calculating the mean values for white blood cells (WBC), absolute neutrophil count (ANC), and absolute lymphocyte count (ALC) at baseline and for C 1-4. Additionally, the incidence of FN and G3-4 hematological toxicities during all ddCtx cycles was recorded. Results: Mean baseline values for WBC, ANC, and ALC were equal in both cohorts. Mean values for WBC, ANC, and ALC [109/L] for cohort P vs L were: cycle 1, 5.88 vs 12.67, 4.06 vs 12.57, 1.06 vs 1.70; cycle 2, 6.49 vs 12.34, 3.60 vs 10.03, 1.03 vs 1.37; cycle 3, 4.88 vs 17.10, 3.41 vs 12.37, 0.92 vs 1.55; cycle 4, 4.99 vs 8.65, 3.18 vs 6.91, 1.11 vs 1.15 with most these differences favoring L over P showing statistical significance. The incidence of FN, G3-4 neutropenia, and G3-4 lymphocytopenia was: cohort P, 2.2%, 5.6%, 5.6%; cohort L, 0%, 3.5%, 7.0% with none of these differences reaching statistical significance. C-CSF-related toxicities were generally manageable and did not significantly differ between both cohorts with: fever, 2 (7.4%) vs 1 (3.8%) pts; chills 2 (7.4%) vs 0 (0%) pts; bone pain, 2 (7.4%) vs 4 (15.4%) pts. Conclusions: LA G-CSFs were safe and effective as FN PP and other severe forms of ddCtx-related leukopenia. The higher hematological efficacy of lipegfilgrastim vs pegfilgrastim did not translate into a higher incidence of side-effects.