 To help increase the blood counts and help decrease the risk of developing infections, your doctor may decide that treatment with filgrastim is necessary. Filgrastim may be given as once-a-day injections under the skin starting 24 hours after the end of Day 4 vincristine Cycle 1 and starting 24 hours after the end of Cytarabine Cycle 2. Your blood counts will be monitored and filgrastim is stopped when the levels become normal. 