Risk Factors and Outcomes of Stem Cell Mobilization Failure in Multiple Myeloma Patients

Satisfactory outcomes following a second autologous hematopoietic cell transplantation for multiple myeloma in poor stem cell mobilizers: a retrospective study on behalf of the Chronic Malignancies Working Party of the EBMT

Autologous hematopoietic cell transplants (auto-HCTs) remain the standard of care for transplant-eligible MM patients. The general practice has been to undergo upfront apheresis following induction to collect sufficient number of CD34+ cells to facilitate two auto-HCTs. However, 5-30% of MM patients do not initially mobilise a sufficient number of hematopoietic stem cells and are classified as poor mobilizers (PM). We compared the baseline characteristics and outcomes of 61 PMs and 816 non-PM patients who underwent a second auto-HCT and who were enrolled in the non-interventional CALM study (NCT01362972). Only patients who collected CD34+ prior to auto-HCT1 were included. Auto-HCT2 comprised both tandem and salvage transplants. PMs were re-mobilized with plerixafor (n = 24, 39.3%) or non-plerixafor-based regimens (n = 37, 60.7%). There were no significant differences in engraftment, progression-free survival (PFS) or overall survival (OS) after the second auto-HCT between PM and non-PM patients. There was a trend to shorter PFS in PM patients undergoing salvage auto-HCT (median 9.6 vs. 12.9 months; p = 0.08) but no significant difference in OS. The median OS was 41.1 months for PM and 41.2 months for non-PM patients (p = 0.86). These data suggest that salvage mobilization is effective and does not affect overall outcomes after a second auto-HCT.

Combined peripheral blood monocyte count and white blood cell count as a guide for successful one-day autologous peripheral blood stem cell collection

INTRODUCTION

Peripheral blood stem cells (PBSCs) are the most common source of stem cell transplantation, which depends on an adequate number of CD34+ cells. Although pre-apheresis CD34+ cell count is a standard guide for the collection, it is not always available. This study aimed to evaluate complete blood count parameters for predicting successful one-day autologous PBSC collection.

METHODS

Data from the patients who underwent autologous PBSC collection at a tertiary care hospital were retrospectively reviewed.

RESULTS

There were 123 patients (185 leukapheresis procedures). Successful PBSC collection (CD34+ cells ≥4.0 × 106 cells/kg) was obtained in 85 patients (69.1%), of which 55 (44.7%) were successfully obtained on the first day. The median CD34+ collection efficiency was 44.1%. The mean platelet loss during apheresis was 39.9%. The adverse event rate was 18.9%. Patients in whom PBSCs were collected within one day were less likely to experience adverse effects related to leukapheresis. Pre-apheresis CD34+ cells ≥10 cells/μLand combined white blood cell (WBC) counts ≥5 × 109/L and/or monocyte ≥10% were independently associated with the successful one-day PBSC collection (adjusted odds ratio 24.06, 95% confidence interval [CI] 5.30-109.10, p < 0.001; and 6.94, 95% CI 1.35-35.79, p = 0.021, respectively). Only pre-apheresis CD34+ cells had a strong correlation with the total stem cell yield.

CONCLUSIONS

To reduce the complication of leukapheresis, the combined pre-apheresis WBC ≥5 × 109/L and/or monocyte ≥10% is a practical parameter to initiate a successfully one-day PBSC collection with or without pre-apheresis CD34+ cell results.

Risk factors of early disease progression and decreased survival for multiple myeloma patients after upfront autologous stem cell transplantation

Multiple myeloma (MM) stands as the second most prevalent hematological malignancy, constituting approximately 10% of all hematological malignancies. Current guidelines recommend upfront autologous stem cell transplantation (ASCT) for transplant-eligible MM patients. This study seeks to delineate factors influencing post-ASCT outcomes in MM patients. Our cohort comprised 150 MM patients from Taipei Veterans General Hospital, with progression-free survival (PFS) as the primary endpoint and overall survival (OS) as the secondary endpoint. A Cox proportional hazards model was employed to discern potential predictive factors for survival. ASCT age ≥ 65 (hazard ratio [HR] 1.94, 95% confidence interval [CI] 1.08-3.47) and the presence of extramedullary disease (HR 2.53, 95% CI 1.53-4.19) negatively impacted PFS. Conversely, treatment response ≥ VGPR before ASCT (HR 0.52, 95% CI 0.31-0.87) and total CD34+ cells collected ≥ 4 × 106 cells/kg on the first stem cell harvesting (HR 0.52, 95% CI 0.32-0.87) were positively associated with PFS. For OS, patients with ISS stage III (HR 2.06, 95% CI 1.05-4.04), the presence of extramedullary disease (HR 3.92, 95% CI 2.03-7.58), light chain ratio ≥ 100 before ASCT (HR 7.08, 95% CI 1.45-34.59), post-ASCT cytomegalovirus infection (HR 9.43, 95% CI 3.09-28.84), and a lower conditioning melphalan dose (< 140 mg/m2; HR 2.75, 95% CI 1.23-6.17) experienced shorter OS. In contrast, post-ASCT day + 15 absolute monocyte counts (D15 AMC) > 500/µl (HR 0.36, 95% CI 0.17-0.79) and post-ASCT day + 15 platelet counts (D15 PLT) > 80,000/µl (HR 0.48, 95% CI 0.24-0.94) were correlated with improved OS. Significantly, early PLT and AMC recovery on day + 15 predicting longer OS represents a novel finding not previously reported. Other factors also align with previous studies. Our study provides real-world insights for post-ASCT outcome prediction beyond clinical trials.

Adverse effects of therapeutic phlebotomies: Prospective study of 587 procedures

BACKGROUND

Therapeutic phlebotomy (TP), a widely used medical procedure, can be performed on diverse patients with iron overload or polyglobulia. However, its adverse events are not well known as most of the information on phlebotomy is derived from healthy blood donors (0.1%-5.3%). In contrast, TP is applicable to a broader, more complex population with comorbidities and old age. To ascertain the incidence of adverse events in phlebotomies, we conducted a prospective study on patients who attended our Unit.

STUDY DESIGN AND METHODS

We prospectively gathered data from patients referred to our Unit for TP. Data regarding demographics, health status, and adverse events within at least 24 h of phlebotomy were gathered via a structured questionnaire during each visit.

RESULTS

Between August 2021 and September 2022, 189 patients underwent 587 procedures. Most patients were men, over 60 (57.3%) had comorbidities, and 93% underwent at least two procedures during the study period. Twenty patients (10.8%) presented 25 adverse events (4.3% of phlebotomies), usually vasovagal reactions, none of which were clinically relevant, and all were managed by nursing staff on site, with full patient recovery.

DISCUSSION

The rate of adverse events (<5%) in patients undergoing TP was low and comparable to that seen in healthy blood donors. Consequently, even old patients and those with some comorbidities can safely undergo TP when the process is carefully managed.

Poor Mobilization-Associated Factors in Autologous Hematopoietic Stem Cell Harvest

Peripheral blood stem cell transplantation (PBSCT) is an important therapeutic measure for both hematologic and non-hematologic diseases. For PBSCT to be successful, sufficient CD34+ cells need to be mobilized and harvested. Although risk factors associated with poor mobilization in patients with hematologic diseases have been reported, studies of patients with non-hematologic diseases and those receiving plerixafor are rare. To identify factors associated with poor mobilization, data from autologous PBSC harvest (PBSCH) in 491 patients were retrospectively collected and analyzed. A multivariate analysis revealed that in patients with a hematologic disease, an age older than 60 years (odds ratio [OR] 1.655, 95% confidence interval [CI] 1.049-2.611, p = 0.008), the use of myelotoxic agents (OR 4.384, 95% CI 2.681-7.168, p < 0.001), and a low platelet count (OR 2.106, 95% CI 1.205-3.682, p = 0.009) were associated with poor mobilization. In patients with non-hematologic diseases, a history of radiation on the pelvis/spine was the sole associated factor (OR 12.200, 95% CI 1.934-76.956, p = 0.008). Among the group of patients who received plerixafor, poor mobilization was observed in 19 patients (19/134, 14.2%) and a difference in the mobilization regimen was noted among the good mobilization group. These results show that the risk factors for poor mobilization in patients with non-hematologic diseases and those receiving plerixafor differ from those in patients with hematologic diseases; as such, non-hematologic patients require special consideration to enable successful PBSCH.