ONE YEAR OF BIOSIMILAR FILGRASTIM IN ROUTINE CLINICAL PRACTICE

Objectives: The use of biosimilar filgrastim has been debated for the limited experience at the time of the approval. We performed a retrospective data analysis of 52 patients who underwent and completed a chemotherapy line for advanced solid tumour and received primary (n=46) or secondary (n=6) prophylaxis with biosimilar filgrastim (Zarzio®). Methods: All hospital day patients with an expected risk of FN >20% (n=21) or FN risk < 20% at high risk for infection (n=25), received 3 days (days 2−4) primary prophylaxis with subcutaneous bolus injections of Zarzio® 300 μg/die. Uneligible patients who developed severe neutropenia after the first cycle, received secondary prophylaxis. Blood tests were performed at the nadir and the day before chemotherapy. The primary end-point was to evaluate the efficacy and tolerability of Zarzio® in terms of severe neutropenia or overall FN incidence and duration. Results: Our retrospective data analysis involved 52 patients (median age 59.2 years) with fifteen aged ≥65 years and median body weight of 70 kg who received a total of 243 chemotherapy cycles (median 4.6 cycles/patient) and 651 Zarzio® administrations (median 12.5 administrations/patient). Severe neutropenia was recorded in 29/452 blood tests. None of the patients developed FN. Two patients received prophylactic antibiotics for severe neutropenia. None of the patients delayed the treatment for bone marrow toxicity. Conclusion: Our data confirmed the efficacy and safety of Zarzio® in routine clinical practice. The use of a three days schedule is actually under debate; longer schedule (5 up to 10 days) could improve the outcome