A Comparison of Proposed Biosimilar LA-EP2006 and Reference Pegfilgrastim for the Prevention of Neutropenia in Patients With Early-Stage Breast Cancer Receiving Myelosuppressive Adjuvant or Neoadjuvant Chemotherapy: Pegfilgrastim Randomized Oncology (Supportive Care) Trial to Evaluate Comparative Treatment (PROTECT-2), a Phase III, Randomized, Double-Blind Trial

Background. Pegfilgrastim is widely used for the prevention of chemotherapy-induced neutropenia. In highly regulated markets, there are currently no approved biosimilars of pegfilgrastim. Pegfilgrastim Randomized Oncology (Supportive Care) Trial to Evaluate Comparative Treatment (PROTECT-2) was a confirmatory efficacy and safety study designed to compare proposed biosimilar LA-EP2006 with reference pegfilgrastim(Neulasta, Amgen) in early-stage breast cancer patients receiving adjuvant or neoadjuvant myelosuppressive chemotherapy. Methods. A total of 308 patients were randomized to LA-EP2006 or reference pegfilgrastim. Each patient received TAC (intravenous docetaxel 75 mg/m(2), doxorubicin 50 mg/m(2), and cyclophosphamide 500 mg/m(2)) on day 1 of each cycle, for six or more cycles. Pegfilgrastim (LA-EP2006 or reference) was given subcutaneously (6 mg in 0.6 mL) on day 2 of each cycle. The primary endpoint was duration of severe neutropenia (DSN) during cycle 1 (number of consecutive days with an absolute neutrophil count, <0.5x10(9)/L), with equivalence confirmed if 90% and 95% confidence intervals (CIs) were within a 1-day margin. Results. Baseline characteristics were well balanced. DSN was equivalent between groups at mean +/- SD 1.36 +/- 1.13 (LA-EP2006, n=155) and 1.19 +/- 0.98 (reference, n=153) in cycle 1. With a treatment difference (reference minus LA-EP2006) of -0.16 days (90% CI-0.36 to 0.04;95% CI-0.40 to 0.08), LA-EP2006 was equivalent to reference pegfilgrastim. Secondary efficacy parameters were similar between groups during cycle 1 and across cycles. Safety profiles were also similar between groups. No neutralizing antibodies against pegfilgrastim, filgrastim, or polyethylene glycol were detected. Conclusion. LA-EP2006 and reference pegfilgrastim were therapeutically equivalent and comparable regarding efficacy and safety in the prevention of neutropenia in patients with early-stage breast cancer receiving TAC.