There are limited data available supporting the use of the recombinant granulocyte colony-stimulating factor (G-CSF), tbo-filgrastim, rather than traditionally used filgrastim to mobilize peripheral blood stem cells (PBSC) or to accelerate engraftment after autologous stem cell transplantation (ASCT). We sought to compare the efficacy and cost of tbo-filgrastim to filgrastim in these settings. Patients diagnosed with lymphoma or plasma cell disorders undergoing G-CSF mobilization, with or without plerixafor, were included in this retrospective analysis. The primary outcome was total collected CD34(+) cells/kg. Secondary mobilization endpoints included peripheral CD34(+) cells/μL on days 4 and 5 of mobilization, adjunctive use of plerixafor, CD34(+) cells/kg collected on day 5, number of collection days and volumes processed, number of collections reaching 5 million CD34(+) cells/kg, and percent reaching target collection goal in 1 day. Secondary engraftment endpoints included time to neutrophil and platelet engraftment, number of blood product transfusions required before engraftment, events of febrile neutropenia, and length of stay. A total of 185 patients were included in the final analysis. Patients receiving filgrastim (n = 86) collected a median of 5.56 × 10(6) CD34(+) cells/kg, compared with a median of 5.85 × 10(6) CD34(+) cells/kg in the tbo-filgrastim group (n = 99; P = .58). There were no statistically significant differences in all secondary endpoints with the exception of apheresis volumes processed (tbo-filgrastim, 17.0 liters versus filgrastim, 19.7 liters; P < .01) and mean platelet transfusions (tbo-filgrastim, 1.7 units versus filgrastim, 1.4 units; P = .04). In conclusion, tbo-filgrastim demonstrated similar CD34(+) yield compared with filgrastim in mobilization and post-transplantation settings, with no clinically meaningful differences in secondary efficacy and safety endpoints. Furthermore, tbo-filgrastim utilization was associated with cost savings of approximately $1406 per patient utilizing average wholesale price.
Sipuleucel-T is a therapeutic cancer vaccine approved for the treatment of castration- or hormone-refractory prostate cancer. Through a novel process, it activates the body's own antigen-presenting cells to induce an immune response to prostatic acid phosphatase, a protein found on prostate cancer cells. A treatment course consists of three total infusions spread 2 weeks apart. Throughout all phases of clinical trials, sipuleucel-T has been shown to be safe and well tolerated. Sipuleucel-T has demonstrated an ability to increase overall survival by approximately 4 months when compared with placebo. However, sipuleucel-T has not shown any improvement in affecting patients' time to disease progression.
Background
High-dose post-transplantation cyclophosphamide (PTC) has proven to be a valuable treatment modality for the prevention of graft-versus-host disease (GVHD) after stem cell transplant (SCT). Granulocyte colony stimulating factor (G-CSF) is routinely given after PTC to improve time to engraftment. Historically, based on the Johns Hopkins regimen, G-CSF is given on Day +5 post-SCT. However, this strategy has not been vigorously compared to other dosing strategies. We sought to assess the effect of delayed (Day +10) or omitted administration of G-CSF on various post-SCT outcomes.
Methods
Allogeneic SCT patients receiving PTC at standard dosing of 50 mg/kg daily on Days +3 and +4 were included in this retrospective analysis. G-CSF was given at the labeled dose of 5 mcg/kg (rounded to nearest vial) on Day +10 for 15 consecutive patients then omitted entirely for ten consecutive patients. These results were compared to historical controls that received G-CSF beginning Day +5 after PTC. All patients received antimicrobial prophylaxis with levofloxacin, acyclovir and posaconazole. The primary outcome was to determine time to engraftment defined, as an absolute neutrophil count ≥500, in each group. A complete list of secondary outcomes is below and includes febrile neutropenia and infection rates, incidence of acute GVHD, as well as survival and relapse rates.
Results
Forty-eight patients receiving PTC were included in the final analysis. Patient characteristics and outcomes are described in Table 1. There were no significant differences between the three groups with the exception of cells infused (p=0.03). While there was a longer time to ANC engraftment for patients not receiving GCSF after PTC, this was not statistically significant. Acute GVHD and first year outcomes were unable to be determined at this time for patients not receiving GCSF due to this population not reaching these endpoints at time of submission.
Conclusion
Administration of G-CSF after post transplant cyclophosphamide is not associated with earlier neutrophil engraftment. Secondary endpoints including platelet engraftment, aGVHD, incidence of febrile neutropenia, or infections were similar among all groups. A larger, randomized study is needed to confirm these results.
Disclosures
Bachier: Sanofi: Speakers Bureau; Seattle Genetics: Speakers Bureau.
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