The prognostic impact of peripheral blood progenitor cell dose following high-dose therapy and autologous stem cell transplant for hematologic malignancies

A sticky wicket: Defining molecular functions for CD34 in hematopoietic cells

The CD34 cell surface antigen is widely expressed in tissues on cells with progenitor-like properties and on mature vascular endothelia. In adult human bone marrow, CD34 marks hematopoietic stem and progenitor cells (HSPCs) starting from the bulk of hematopoietic stem cells with long-term repopulating potential (LT-HSCs) throughout expansion and differentiation of oligopotent and unipotent progenitors. CD34 protein surface expression is typically lost as cells mature into terminal effectors. Because of this expression pattern of HSPCs, CD34 has had a central role in the evaluation or selection of donor graft tissue in HSC transplant (HSCT). Given its clinical importance, it is surprising that the biological functions of CD34 are still poorly understood. This enigma is due, in part, to CD34's context-specific role as both a pro-adhesive and anti-adhesive molecule and its potential functional redundancy with other sialomucins. Moreover, there are also critical differences in the regulation of CD34 expression on HSPCs in humans and experimental mice. In this review, we highlight some of the more well-defined functions of CD34 in HSPCs with a focus on proposed functions most relevant to HSCT biology.

Importance of early immune recovery after autologous hematopoietic cell transplantation in lymphoma patients

Lymphomas constitute the second most common indication for autologous hematopoietic cell transplantation (AHCT). Graft infusion is followed by a rapid hematological recovery and slower immune recovery. The number of natural killer cells and CD3⁺ T lymphocytes achieve normal counts usually within a month, whereas the recovery of CD3⁺CD4⁺ T lymphocytes is much slower. Early immune recovery is usually defined as the absolute lymphocyte count (ALC) ≥0.5 × 10⁹/L, which has been associated with improved progression-free and even overall survival. Several factors have been associated with early immune recovery, including higher infused lymphocyte and CD34⁺ cell doses, both of which are affected by the choice of mobilization. This review summarizes the clinical importance of early immune recovery for long-term success of AHCT in lymphomas. Factors known to affect early immune recovery are discussed and suggestions made how to improve mobilization and collection processes to optimize immune recovery and post-transplant outcomes.

Outcome of autologous hematopoietic stem cell transplant in older patients with B cell lymphoma when selected for fitness and chemosensitive disease

BACKGROUND

Autologous hematopoietic stem cell transplantation (AHSCT) in the older population is associated with an increased risk of morbidity and mortality. Determination of the hematopoietic cell transplant comorbidity index (HCT-CI) has contributed to improve patient selection while allowing prediction of their non-relapse mortality (NRM). The goal of this study was to identify factors influencing both safety and efficacy of AHSCT in an older non-Hodgkin lymphoma (NHL) population to better select those who will benefit from this intervention in the Canadian context of a single-payer government healthcare program.

METHODS

This single center, retrospective study, examined clinical outcomes in 90 consecutive older patients (≥60 years old) with B-cell NHL treated with AHSCT between 2008 and 2014.

FINDINGS

Median age was 63 (60-69) at time of transplantation. The HCT-CI risk score was low, intermediate and high in 34%, 40% and 26% of patients, respectively. NRM was 1% at 100 days and one-year post transplant and not influenced by age. At a median follow-up of 52 months, median progression-free survival (PFS) was 56 months while median overall survival (OS) was still not reached. Stable and progressive disease status at time of transplantation were associated with a lower PFS (HR 2.94) and OS (HR 3.91). BEAC conditioning and a graft cell dose  5 × 10⁶ CD34+/kg led to faster recovery, decreased toxicity and resource consumption.

INTERPRETATION

In the older population, AHSCT is safe and optimal when restricted to fit chemosensitive patients.

The effect of the dexamethasone, cytarabine, and cisplatin (DHAP) regimen on stem cell mobilization and transplant outcomes of patients with non-Hodgkin's lymphoma who are candidates for up-front autologous stem cell transplantation

BACKGROUND/AIMS

Data on dexamethasone, cytarabine, and cisplatin (DHAP) as a mobilization regimen, compared to high-dose cyclophosphamide (HDC), for up-front autologous stem cell transplantation (ASCT) in non-Hodgkin's lymphoma (NHL) is limited.

METHODS

Consecutive patients with aggressive NHL treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or rituximab-CHOP who underwent chemomobilization using HDC or DHAP plus granulocyte-colony stimulating factor (G-CSF) for up-front ASCT were enrolled from three institutions between 2004 and 2014.

RESULTS

Ninety-six patients (57 men) were included. Sixty-five patients (67.7%) received HDC; and 31 (32.3%), DHAP. The total CD34+ cells mobilized were significantly higher in patients receiving DHAP (16.1 vs. 6.1 × 106/kg, p = 0.001). More patients achieved successful mobilization with DHAP (CD34+ cells ≥ 5.0 × 106/kg) compared to HDC (87.1% vs. 61.5%, respectively; p = 0.011), particularly within the first two sessions of apheresis (64.5% vs. 32.3%, respectively; p = 0.003). Mobilization failure rate (CD34+ cells < 2.0 × 106/kg) was significantly higher in patients receiving HDC (20.0% vs. 3.2%, p = 0.032). On multivariate analysis, the DHAP regimen (odds ratio, 4.12; 95% confidence interval, 1.12 to 15.17) was an independent predictor of successful mobilization. During chemomobilization, patients receiving HDC experienced more episodes of febrile neutropenia compared to patients receiving DHAP (32.3% vs. 12.9%, p = 0.043).

CONCLUSION

The DHAP regimen was associated with a significantly higher efficacy for stem cell mobilization and lower frequency of febrile neutropenia. Therefore, DHAP plus G-CSF is an effective for mobilization in patients with aggressive NHL who were candidates for up-front ASCT.

Italian consensus conference for the outpatient autologous stem cell transplantation management in multiple myeloma

Multiple myeloma (MM) is the leading indication for autologous stem cell transplantation (ASCT) worldwide. The safety and efficacy of reducing hospital stay for MM patients undergoing ASCT have been widely explored, and different outpatient models have been proposed. However, there is no agreement on the criteria for selecting patients eligible for this strategy as well as the standards for their clinical management. On the basis of this rationale, the Italian Group for Stem Cell Transplantation (GITMO) endorsed a project to develop guidelines for the management of outpatient ASCT in MM, using evidence-based knowledge and consensus-formation techniques. An expert panel convened to discuss the currently available data on the practice of outpatient ASCT management and formulated recommendations according to the supporting evidence. Evidence gaps were filled with consensus-based statements. Three main topics were addressed: (1) the identification of criteria for selecting MM patients eligible for outpatient ASCT management; (2) the definition of standard procedures for performing outpatient ASCT (model, supportive care and monitoring during the aplastic phase); (3) the definition of the standard criteria and procedures for re-hospitalization during the aplastic phase at home. Herein, we report the summary and the results of the discussion and the consensus.