Tbo or Not Tbo-That Is the Question!

Growth factors are routinely used after autologous transplantation to shorten the duration of neutropenia.  Tbo-filgrastim (TBO) was recently approved in the U.S. for patients with non-myeloid malignancies. The Average Wholesale Price for TBO is  20% less than Filgrastim (FGS). Whether TBO is comparable to FGS for reducing time to engraftment following HSCT is unknown. A cost-savings initiative was undertaken at Northwestern Memorial Hospital to substitute TBO for FGS in all autografts.  Herein are the results of an observational study which compares TBO and FGS.

 FGS patients were treated from10/2013-4/14/2014 and TBO patients between 4/15/14-9/20/2014. All patients were treated for multiple myeloma with melphalan 200mg/m2. TBO and FGS were initiated day+5 after stem cell infusion,  and discontinued the first day the absolute neutrophil exceeded  1000/ml.   Time to engraftment was defined as  the number of days from stem cell re-infusion until  the first day the  ANC exceeded 500cell/ml. TBO and FGS dose was rounded as follows:  <80kg received 300mcg/day, >80mg<120kg received 480mcg and those > 120kg received 600mcg/day.

96 consecutively treated patients were included- 48 treated with TBO and 48 treated with FGS.  No significant difference was observed  for diagnosis, age, gender, weight, BSA, growth factor dose or  dose/kg, number of stem cells infused,  number of patients who developed febrile neutropenia or microbiologically proven infection or prolonged fever (>48 hours). 

Median time to engraftment and delayed engraftment (>14days) were significantly longer in the TBO-treated patients. There was no difference in overall length of stay or hospital mortality.

TBO-filgastrim appears to be effective in reducing the time of neutropenia and stem cell engraftment. However delayed engraftment, especially as observed >14 days after stem cell infusion, was observed significantly more often in TBO treated patients compared to those treated with FGS. These results require confirmation through a large randomized trial.