Absolute Neutrophil Count (Anc) Pattern With Accelerated Dose-Intensified Epirubicin Chemotherapy And Pegfilgrastim Support

8229 Background: Several randomized studies evaluating pegfilgrastim and filgrastim have shown no difference in ANC patterns in cycle 2 compared to cycle 1 of chemotherapy. We have observed an interesting ANC pattern in a phase II clinical study evaluating the safety and efficacy of accelerated dose- intensified neoadjuvant epirubicin with pegfilgrastim support in patients with breast cancer. Methods: Biopsy proven stage II/III breast cancer patients with primary tumors >2 cm and adequate hematologic, hepatic, renal, and cardiac function are eligible. Single agent epirubicin is given at 120 mg/m2 every 14 days for four cycles with pegfilgrastim support (6 mg subcutaneously once per cycle 24 hours following each treatment). Definitive surgery is performed 3–4 weeks after completion of chemotherapy. Postoperative therapy is given at the discretion of the investigator. Planned accrual is 30 patients. Results: To date 6 patients have been treated. All 6 have completed chemotherapy, and have undergone surgery. Two patients achieved a clinical complete response, 3 patients had a partial response, and 1 patient has stable disease. Grade 4 neutropenia (ANC<0.5 k/uL) was noted in all 6 patients following cycle 1 of chemotherapy. During cycles 2–4, no grade 4, and only 1 case of grade 3 neutropenia (ANC<0.5 k/uL) was observed in a total of 18 cycles of therapy given (Table). Conclusions: Accelerated, dose intensified epirubicin with pegfilgrastim is safe and appears efficacious as neoadjuvant therapy. The finding of grade 4 neutropenia in all patients after the first dose of epirubicin, but decreased myelosuppression with subsequent chemotherapy cycles suggests a “priming” effect of pegfilgrastim and warrants further study. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Pfizer