Real-World Evidence Shows Biosimilar Filgrastim Safe, Effective Against Febrile Neutropenia

Febrile neutropenia (FN) is among the most common complications of chemotherapy, and a recent post-marketing, multi-center, real-world, non-interventional, epidemiological study sought to examine the use, safety, and efficacy of biosimilar filgrastim in the primary and secondary prevention of FN.

Secondary prevention of FN is typically offered to a patient who is in a low-risk category for developing FN, but who develops FN during chemotherapy. Primary prevention of FN is offered to high-risk patients with each cycle of chemotherapy. Of the 170 study participants, an overall risk assessment conducted at the first patient visit resulted in the following determinations:

• 4.1% of participants were identified as having less than a 10% risk of developing FN
• 35.9% were identified as having a 10% to 20% risk
• 60% were identified as having a greater than 20% risk
• In 74.7% of cases, additional risk factors for FN—including anemia, diabetes, comorbidities, cancer stage, and others—were identified.

After the risk assessment, 60% of patients received biosimilar filgrastim (Accofil, manufactured by Accord Healthcare, who sponsored the study) as primary prevention of FN, and 40% received biosimilar treatment as secondary prevention. During the second to fifth patient visit (though in 40.6% of patients, 6 cycles of chemotherapy were planned, and in 28.2% of cases, more than 6 cycles were planned), the course of therapy with biosimilar filgrastim was monitored. Data collected, via questionnaire, included the following:

• Chemotherapy dose density
• Occurrence of FN following the previous cycle of treatment
• Continuation of filgrastim in subsequent cycles of chemotherapy
• Total dose of filgrastim
• Administration (ie, whether the filgrastim was self-injected or injected by a healthcare provider)
• Presence of pain
• Convenience of use (according to patient opinion)
• Hematological parameters of peripheral blood (including leukocyte count, absolute neutrophil count, hemoglobin concentration, and platelet count)

The researchers calculated continuation of therapy with biosimilar filgrastim, average dose of filgrastim, chemotherapy dosage, and FN at each of the 5 visits, and found the following:

• Week 1: average (mean) dose of filgrastim was 220.9 (±84.4) million units
• Week 2: 98.2% continued treatment at an average dose of 222.4 (±87.2) million units, 95.3% of patients continued chemotherapy at the same dose as the prior week, and 92.9% reported no FN
• Week 3: 96.4% continued treatment at an average dose of 223.9 (±90.3) million units, 94.7% continued chemotherapy at the same dose, and 94.1% reported no FN
• Week 4: 91.3% continued treatment at an average dose of 231.6 (±95.7) million units, 96.2% continued chemotherapy at the same dose, and 91.2 reported no FN
• Week 5: 86.3% continued treatment at an average dose of 224.8 (±98.8) million units, 90.4% continued chemotherapy at the same dose, and 92.6% reported no FN

An assessment of patient reports found that 70% of patients self-administered the filgrastim injection, and at each visit, over 50% of patients reported “little” soreness caused by the injection. Patient assessments of the convenience of use (on a scale of 1 to 10, where 1 is the least convenient and 10 is the most convenient), showed that approximately 50% of patients rated the convenience of administration as greater than 8.

Assessment of hematological parameters showed that the median neutrophil count identified at visit 1 (2.2×103/µl) did not fall during any of the 5 visits.

The researchers concluded that biosimilar filgrastim was safe, effective, and well tolerated in patients in the primary and secondary prevention of chemotherapy-induced FN, and that administration of the drug was convenient for, and well accepted by, patients.