A Phase III, Randomized, Multi-Center, Open-Label, Fixed Dose, Neulasta Active-Controlled Clinical Trial of F-627, a Novel G-CSF, in Women with Breast Cancer Receiving Myelotoxic Chemotherapy

Background - Chemotherapy-induced neutropenia (CIN) is the primary dose-limiting toxicity in patients receiving myelotoxic chemotherapy which is associated with increased morbidity and early mortality. Ryzneuta ^TM (F-627), a recombinant fusion protein containing human granulocyte-colony stimulating factor (G-CSF) and IgG2-Fc fragment, is intended to reduce CIN by utilizing the neutrophilic proliferating and activating properties of G-CSF. F-627 was designed as a novel, non-pegylated molecule with dimeric G-CSF, which may possess stronger G-CSF receptor activating properties and improved efficacy compared to filgrastim and pegfilgrastim. The primary objective of this study was to evaluate the safety and efficacy of F-627 given as a single fixed dose (20 mg) pre-filled syringe (PFS) as compared to Neulasta® (6 mg) in the first chemotherapy cycle.

Methods - This was a phase III, multi-center, randomized, open-label, two-arm, active-controlled study that randomized female patients with Stage I to III invasive breast cancer who received 4 cycles of myelotoxic taxane + cyclophosphamide chemotherapy treatment. Forty-one (41) sites across 5 countries participated in the trial, including Bulgaria, Hungary, Russia, Ukraine, and US. Patients were randomized to F-627 or Neulasta® in a 1:1 ratio on the day of chemotherapy and administered study drug 24 hours after chemotherapy administration in each cycle. A total of 393 patients were randomized and analyzed for efficacy and safety. Clinical assessments were cycle-specific and included physical examination, serum samples for immunogenicity before each chemotherapy cycle, laboratory assessments, hematology and CBC with differentials, urinalysis, body weight, vital signs, adverse event (AE) collection, and concomitant medications. The pharmacokinetics (PK) and the pharmacodynamics (PD) of F-627 were also assessed. The primary efficacy endpoint was the duration in days of Grade 4 (severe) neutropenia (ANC <0.5 × 10 ⁹/L) during cycle 1 of chemotherapy.

Results - The mean duration of Grade 4 neutropenia in chemotherapy cycle 1 was 0.2 days for both F-627 and Neulasta®. F-627 was non-inferior compared to Neulasta® for the duration of Grade 4 neutropenia in chemotherapy cycle 1 with a mean difference of 0.0 days (95% CI: -0.1, 0.1), utilizing a non-inferiority margin of 0.6 days. The incidence of Grade 4 neutropenia in chemotherapy cycle 1 was comparable between F-627 and Neulasta®, 11.7% for both treatment groups. For chemotherapy cycles 2, 3, and 4, the incidence and duration of Grade 4 neutropenia was generally lower than in chemotherapy cycle 1. The mean durations of Grade 4 neutropenia were 0.1, 0.0, and 0.0 days for F-627 and 0.1, 0.1, and 0.1 days for Neulasta® in chemotherapy cycles 2,3,4, respectively. The incidence of Grade 4 neutropenia was 4.6%, 2.6%, and 1.6% for F-627 and 5.1%, 6.3%, and 5.3% for Neulasta® in chemotherapy cycles 2, 3, and 4, respectively. Across all chemotherapy cycles and for each chemotherapy cycle, the mean duration and the incidence of IV antibiotic use and hospitalization due to febrile neutropenia or any infection were low and comparable between F-627 and Neulasta®. The depth of ANC nadir was comparable in each chemotherapy cycle between F-627 and Neulasta®. For each chemotherapy cycle, time to ANC nadir was slightly longer for patients treated with F-627 than those with Neulasta®; the mean time to ANC nadir was 6.4, 6.1, 6.2, and 6.2 days for F-627, compared to 6.1,5.3, 5.7, and 5.5 days for Neulasta® in cycles 1, 2, 3, and 4, respectively. F-627 was well tolerated, with a low incidence of serious AEs and AEs leading to discontinuation, comparable to the profile for Neulasta®. There were 3 deaths during the study (1 for F-627 and 2 for Neulasta®). None of the deaths were related to study drug treatment. Clinical laboratory abnormalities were observed to be similar between the two treatment groups.

Conclusion - Once-per-cycle F-627, given as a fixed 20 mg dose, was non-inferior to Neulasta® in reducing the duration of severe neutropenia following TC chemotherapy. F-627 was well tolerated during the study with an overall safety profile comparable to that for Neulasta®. F-627 is a safe, effective, and easy to use alternative to current CIN therapy.