Vials of drug
The US Food and Drug Administration (FDA) has approved tbo-filgrastim (Granix) injection for administration by patients and caregivers, allowing physicians to prescribe the drug for in-office or at-home use.
Tbo-filgrastim is a leukocyte growth factor used to reduce the duration of severe neutropenia in patients with non-myeloid malignancies who are receiving myelosuppressive anticancer drugs associated with a clinically significant incidence of febrile neutropenia.
The drug has been commercially available in the US since November 2013, but, at present, it can only be administered by a healthcare professional.
Teva Pharmaceutical Industries, Ltd., the company developing tbo-filgrastim, plans to launch the new syringe for administration by patients and caregivers in early 2015.
Clinical trials
Researchers evaluated tbo-filgrastim in 3 phase 3 trials of patients receiving myelosuppressive chemotherapy for breast cancer, lung cancer, and non-Hodgkin lymphoma (NHL).
In the NHL study, investigators compared tbo-filgrastim to filgrastim for the prevention of chemotherapy-induced neutropenia in 92 patients.
For cycle 1, patients were randomized to daily injections (subcutaneous 5 µg/kg/day) of tbo-filgrastim (n=63) or filgrastim (n=29) for at least 5 days and a maximum of 14 days. In subsequent cycles, all patients received tbo-filgrastim.
In cycle 1, the mean duration of severe neutropenia was 0.5 days in the tbo-filgrastim arm and 0.9 days in the filgrastim arm (P=0.1055). The incidence of febrile neutropenia was 11.1% and 20.7%, respectively (P=0.1232).
In the lung cancer trial, researchers compared tbo-filgrastim to filgrastim in 240 patients receiving platinum-based chemotherapy. In cycle 1, patients were randomized to daily injections (subcutaneous 5 µg/kg/d) of tbo-filgrastim (n=160) or filgrastim (n=80) for at least 5 days and a maximum of 14 days. In subsequent cycles, all patients received tbo-filgrastim.
In cycle 1, the mean duration of severe neutropenia was 0.5 days in the tbo-filgrastim arm and 0.3 days in the filgrastim arm. There was no significant difference in the incidence of febrile neutropenia in cycle 1 between the two arms (P=0.2347).
In the breast cancer trial, investigators compared tbo-filgrastim to filgrastim or placebo in 348 patients receiving chemotherapy. Patients were randomized to daily injections (subcutaneous 5 µg/kg/day) for at least 5 days and a maximum of 14 days in each cycle of tbo-filgrastim (n=140), filgrastim (n=136), or placebo (n=72).
The mean duration of severe neutropenia in cycle 1 was 1.1 days in the tbo-filgrastim arm, 1.1 days in the filgrastim arm, and 3.9 days in the placebo arm.
In all the trials, bone pain was the most frequent treatment-emergent adverse event, occurring in at least 1% of patients treated with tbo-filgrastim at the recommended dose. The overall incidence of bone pain in cycle 1 was 3.4% for tbo-filgrastim, 1.4% for placebo, and 7.5% for filgrastim.
According to the drug’s prescribing information, tbo-filgrastim may pose a risk of splenic rupture, acute respiratory distress syndrome, serious allergic reactions, severe and sometimes fatal sickle cell crises, and capillary leak syndrome. The possibility that the drug acts as a growth factor for tumors cannot be excluded.
