Abstract CT116: Same-day administration of Eflapegrastim with chemotherapy enhances neutropenic recovery in neutropenic rats and in early-stage breast cancer patients

Background: Chemotherapy-induced neutropenia increases the likelihood of life-threatening infections. Currently, long-acting G-CSF products are administered 24 hours after chemotherapy (CT). Eflapegrastim9s (Efla) greater marrow resident time should provide a pharmacodynamic advantage over pegfilgrastim (Peg), translating into a shorter duration of neutropenia (DN). The therapeutic potential of Efla, a long-acting G-CSF, was evaluated in a neutropenic rat model where neutropenia was induced via intraperitoneal docetaxel/cyclophosphamide. This study compared the DN with that of vehicle control and Peg at 0, 2, 5, and 24 hrs post-CT. We found that at all-time points, there was a marked reduction in the degree of neutropenia and a more rapid rate of absolute neutrophil count (ANC) recovery with Efla compared to Peg. When Efla was administered concomitantly with CT, ANC returned to normal within 12hrs for Efla vs 2.2 days post-nadir for Peg, while the DN in the vehicle group was 7 days. Pharmacokinetics (PK) of Efla for same-day dosing were similar to those reported for next-day dosing. Based on these results, a Phase 1 clinical trial is ongoing; results for the first 9 patients are reported. Material and Methods: Phase 1, open-label study where Efla is administered at a fixed dose of 13.2 mg at 0.5, 3, and 5 hours s.c. after the i.v. infusion of docetaxel (75 mg/m2) and cyclophosphamide (600 mg/m2) CT in patients with confirmed stage I-IIIA breast cancer. Patients >18 years, ECOG Citation Format: John A. Barrett, Shanta Chawla, Prasad S. Kolli, Yu- Yon Kim, Sri Lakshmikanthan, Meera Tugnait, Lyndah K. Dreiling, Francois Lebel. Same-day administration of Eflapegrastim with chemotherapy enhances neutropenic recovery in neutropenic rats and in early-stage breast cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT116.