When should I use filgrastim after autologous transplantation in MM patients?

Granulocyte colony-stimulating factor (G-CSF) is routinely administered following autologous stem cell transplantation in patients with multiple myeloma (MM); however, the optimal timing for its initiation remains unclear. While previous studies have evaluated heterogeneous patient cohorts, including those with MM, Non-Hodgkin's Lymphoma, and Hodgkin's Lymphoma, this study focuses exclusively on MM patients. We aimed to compare the outcomes of initiating G-CSF either on day + 1 post-transplantation or upon the onset of neutropenia, with particular emphasis on neutrophil and platelet engraftment times, to help define an optimal G-CSF administration strategy in this patient population.

This retrospective study included 122 MM patients who underwent autologous hematopoietic stem cell transplantation between 2016 and 2022 at the Hematology Clinic of İnönü University Turgut Özal Medical Center. Patients were evenly divided into two groups. In Group 1, filgrastim was initiated on day + 1 post-transplantation, while in Group 2, it was administered after the onset of neutropenia. Neutrophil and platelet engraftment times, as well as antibiotic usage, were compared between the groups.

There were no statistically significant differences in neutrophil or platelet engraftment times or in antibiotic usage between the two groups (p > 0.05). The median neutrophil and platelet engraftment times were 14 and 15 days, respectively, in the day + 1 group, and 15 and 14 days in the neutropenia-guided group. However, the median number of filgrastim injections was significantly lower in the neutropenia group (8 injections, range: 6-12) compared to the day + 1 group (14 injections, range: 8-24) (p < 0.001).

Initiating G-CSF upon the development of neutropenia is as effective as early (day +1) administration in MM patients undergoing autologous transplantation. This delayed strategy does not adversely affect engraftment or antibiotic requirements and significantly reduces the number of G-CSF injections, offering potential benefits in terms of cost-effectiveness and reduced side effects.