An effective mobilization strategy for lymphoma patients after failed upfront mobilization with plerixafor

Impact of mobilization regimen on multiday collection of peripheral blood CD34+ cells by large volume leukapheresis

BACKGROUND

The collection yield of hematopoietic progenitors cell (HPC) by leukapheresis is critical for a successful transplantation, which often requires multiday collections to achieve the collection goal.

STUDY DESIGN AND METHODS

Collection procedures of 181 patients who underwent leukapheresis for more than 1 day were reviewed. Patients were separated into six groups based on the mobilization regimen: G-CSF on day 1 (D1) and day 2 (D2) (G-G); G-CSF on D1 and G-CSF and plerixafor on D2 (G-GP); G-CSF and plerixafor on day D1 and D2 (GP-GP); G-CSF and plerixafor on D1 and G-CSF on D2 (GP-G); chemotherapy and G-CSF on D1 and D2 (GC-GC); and chemotherapy, G-CSF, and plerixafor on D1 and D2 (GCP-GCP). Patient's pre-collection CD34 count (pre-CD34) on D1 and D2 were compared in the same individual and among groups.

RESULTS

We found D2 pre-CD34 were significantly decreased in G-G, GP-G, and GP-GP groups and significantly increased in G-GP group (p < .001) using a repeated measures ANOVA analysis. D2 pre-CD34 remained at similar levels as D1 in GC-GC and GCP-GCP groups. A multiple regression analysis showed that the mobilization regimen was the only factor that significantly affected pre-CD34 D2/D1 ratio (p < .001). There was a significant difference in the pre-CD34 D2/D1 ratio (p < .001) among these six groups with the lowest in GP-G group (0.40 ± 0.45), and the highest in G-GP group (2.35 ± 0.36).

DISCUSSION

Mobilization regimen has significant impact on pre-collection CD34 count. Apheresis facilities may change mobilizing drugs accordingly to achieve a specific HPC goal.

Etoposide + Granulocyte Colony-Stimulating Factor and Optional Plerixafor in Patients Who Failed Chemomobilization with or without Plerixafor

We conducted a retrospective study of 62 patients undergoing etoposide (2 g/m²) + granulocyte colony-stimulating factor (G-CSF; 10 patients also received additional plerixafor) as a salvage stem cell mobilization regimen after previous unsuccessful chemomobilization with or without plerixafor. The median peak CD34⁺ values after etoposide + G-CSF ± plerixafor was 54.07 CD34⁺/μL compared with 9.6 CD34⁺/μL after previous mobilization attempts (P < .001). The median yield was 6.33 × 10⁶ CD34⁺ cells/kg per 2 apheresis. Etoposide + G-CSF ± plerixafor mobilization regimen resulted in 91.53% successful mobilizations and 89.83% of patients proceeding to autologous stem cell transplantation. All 7 patients who had previously failed plerixafor-based mobilization attempts were successfully mobilized with etoposide + G-CSF ± plerixafor and proceeded to autologous stem cell transplantation. The most common grades 3 to 4 adverse events of etoposide + G-CSF ± plerixafor were febrile neutropenia (69.35%), mucositis (51.62%), and bacteremia (20.97%). No fatal outcomes were observed. Rates of 12-month overall survival and progression-free survival were 88.71% and 70.97%, respectively. Etoposide + G-CSF ± plerixafor is an effective regimen for salvage stem cell mobilization also in patients who failed plerixafor, with most patients undergoing autologous stem cell transplantation. The adverse event rate may warrant a decrease in the dose of etoposide.

Expression of adhesion molecules on CD34+ cells from steady-state bone marrow before and after mobilization and their association with the yield of CD34+ cells

Background

Cell adhesion molecules (CAMs) expressed on hematopoietic progenitor cells (HPCs), endothelial cells, and stromal cells play a pivotal role in the mobilization of CD34+ cells. Herein, we conducted a non-randomized peripheral blood stem cell (PBSC) mobilization study aimed to compare the potential differences in the expressions of several CAMs and chemokines on CD34+ cells obtained from bone marrow aspirate before and after HPC mobilization from patients with hematologic malignancies and healthy donors.

Methods

Three-color cytofluorometric analysis was used to compare the expressions of CAMs and chemokines in the bone marrow before and after mobilization.

Results

For all studied groups, CAM expression among those with good and poor yields of CD34+ cells was significantly correlated with VCAM-1 (P=0.007), CD44 (P=0.027), and VLA-4 (P=0.014) expressions. VCAM-1 (P=0.001), FLT-3 (P=0.001), CD44 (P=0.011), VLA-4 (P=0.001), and LFA-1 (P=0.001) expressions were higher before HPC mobilization than after HPC mobilization. By contrast, the expression of CXCR4 significantly varied before and after mobilization only among those with successful PBSC mobilization (P=0.002).

Conclusion

We attempted to identify particular aspects of CAMs involved in CD34+ cell mobilization, which is a highly complex mechanism that involves adhesion molecules and matrix metalloproteases. The mechanism by which CD34+ cell mobilization is activated through proteolytic enzymes is not fully understood. We believe that CXCR4, VLA-4, CD44, and VCAM-1 are the most important molecules implicated in HPC mobilization, particularly because they show a correlation with the yield of CD34+ cells collected via large volume leukapheresis.

A single center's experience using four different front line mobilization strategies in lymphoma patients planned to undergo autologous hematopoietic cell transplantation

In an otherwise eligible patient with relapsed lymphoma, inadequate mobilization of peripheral blood stem cells is a limiting factor to proceeding with an autologous hematopoietic cell transplantation (auto-HCT). Multiple strategies have been used to mobilize an adequate number of hematopoietic stem cells (HSCs) with no obvious front-line strategy. We report a single institutional experience mobilizing HSCs using four different approaches in lymphoma patients. We prospectively collected mobilization outcomes on patients planning to undergo auto-HCT at Ohio State University. We report results of first mobilization attempt for all relapsed or refractory lymphoma patients between 2008–2014. We identified 255 lymphoma patients who underwent mobilization for planned auto-HCT. The 255 lymphoma patients underwent the following front line mobilization strategies: 95 (37%) GCSF alone, 38 (15%) chemomobilization (GCSF+chemotherapy), 97 (38%) preemptive day 4 plerixafor, and 25 (10%) rescue day 5 plerixafor. As expected, there were significant differences between cohorts including age, comorbid indices, histology, and amount of prior chemotherapy. After controlling for differences between groups, the odds of collecting 2×10⁶/kg HSCs on the first day of collection and 5×10⁶/kg HSCs in total was highest in the cohort undergoing chemomobilization. In conclusion, our experience highlights the effectiveness of chemomobilization.