Outcomes of poor peripheral blood stem cell mobilizers with multiple myeloma at the first mobilization: A multicenter retrospective study in Japan

Abstract

Autologous stem cell transplantation (ASCT) remains an important therapeutic strategy for multiple myeloma; however, a proportion of patients fail to mobilize a sufficient number of peripheral blood stem cells (PBSCs) to proceed to ASCT. In the present study, we aimed to clarify the characteristics and outcomes of poor mobilizers. Clinical data on poorly mobilized patients who underwent PBSC harvest for almost 10 years were retrospectively collected from 44 institutions in the Japanese Society of Myeloma (JSM). Poor mobilizers were defined as patients with less than 2 × 10 6 /kg of CD34 + cells harvested at the first mobilization. The proportion of poor mobilization was 15.1%. A sufficient dataset including overall survival (OS) was evaluable in 258 poor mobilizers. Overall, 92 out of 258 (35.7%) poor mobilizers did not subsequently undergo ASCT, mainly due to an insufficient number of PBSCs. Median OS from apheresis was longer for poor mobilizers who underwent ASCT than for those who did not (86.0 vs. 61.9 mon., p = 0.02). OS from the diagnosis of poor mobilizers who underwent ASCT in our cohort was similar to those who underwent ASCT in the JSM database (3y OS rate, 86.8% vs. 85.9%). In this cohort, one-third of poor mobilizers who did not undergo ASCT had relatively poor survival. In contrast, the OS improved in poor mobilizers who underwent ASCT. However, the OS of extremely poor mobilizers was short irrespective of ASCT.

Analysis of Factors Affecting Hematopoietic Stem Cell Mobilization Efficiency and Early Hematopoietic Reconstruction Indicators during Autologous Peripheral Blood Hematopoietic Stem Cell Transplantation

“…Herein, although a sufficient number of CD34þ hematopoietic stem cells were collected, the megakaryocytic hematopoietic reconstruction was delayed due to impaired megakaryocytic generation ability. 19 thrombopoietin (TPO) receptor agonists can increase PLT number in patients with primary immune thrombocytopenia and aplastic anemia by promoting the maturation of the megakaryocytic system. Besides, TPO receptor agonists are widely used for poor PLT engraftment after allogeneic HSCT.…”

“…Herein, although a sufficient number of CD34+ hematopoietic stem cells were collected, the megakaryocytic hematopoietic reconstruction was delayed due to impaired megakaryocytic generation ability. 19 …”

Comparison of peripheral blood automated hematopoietic progenitor cell count and flow cytometric CD34+ cell count

“…15 Furthermore, previously, it was demonstrated that the outcome after ASCT was poorer if lower amounts of stem cells were harvested. 15 Therefore, the best preharvest assessment of the stem cell count is needed to optimize the stem cell harvest and maximize the outcome.…”

“…Preceding studies examining the performance of automated PBSC measurement showed a significant correlation to flow cytometric measurement consequently proposing XN-20 as a possible surrogate marker for initiation of the apheresis procedure. 7,8,10,11,[15][16][17][18][19][20][21] Although, it needs to be mentioned that some point out the diagnostic accuracy in the clinical decision range might be limited. 8 Furthermore, depending on the utilized analyzer the diagnostic accuracy may be confined.…”

Poor Mobilization-Associated Factors in Autologous Hematopoietic Stem Cell Harvest

“…When sufficient CD34 + cells cannot be collected, the patient must either undergo re-harvest or be treated with other options. These cause inconvenience and sometimes worsen clinical outcomes [8][9][10][11]. Previous studies have reported various factors associated with mobilization failure, and some researchers have developed methods to predict CD34 + cell collection yield [12][13][14][15][16][17][18][19].…”