Impact of different dimethyl sulphoxide concentrations on cell recovery, viability and clonogenic potential of cryopreserved peripheral blood hematopoietic stem and progenitor cells.

BACKGROUND AND OBJECTIVES: The procedure of autologous hematopoietic stem/progenitor cell transplantation requires cryopreservation. Addition of DMSO is necessary to secure the viability of such cells, but this solvent is potentially toxic to stem cells' recipient. 10% DMSO solution is used by the majority of transplant centres. The aim of our study was to test if DMSO concentration might be reduced without negative impact on cell recovery and clonogenicity. MATERIALS AND METHODS: Samples were prospectively collected from 20 patients. Small volumes of leukapheresis products were frozen with different cryoprotective mixtures, containing 10%, 7·5%, 5% and 2·5% DMSO, respectively. The quality of cryoprotective mixtures was evaluated based on recovery, viability and clonogenic potential of hematopoietic stem cells after defreezing. RESULTS: Reduction in DMSO concentration to 7·5% or lower was associated with decreased recovery of nucleated cells. In contrast, the number of colonies was highest for 7·5% DMSO with significant differences when compared to 10% DMSO solution. CONCLUSION: Reduction in DMSO concentration from 10% to 7·5% may have favourable impact on hematopoietic recovery after autologous transplantation. The findings require confirmation in a clinical setting.

Trends in allogeneic haematopoietic cell transplantation for myelofibrosis in Europe between 1995 and 2018: a CMWP of EBMT retrospective analysis.

We performed a retrospective assessment of patient- and transplant-specific characteristics and outcomes for 4142 patients undergoing allogeneic haematopoietic cell transplant for myelofibrosis between 1995 and 2018 across 278 centres. Activity increased steadily across the four analysed eras (<2006, 2006-2010, 2011-2014 and 2015-2018). Median recipient age increased over time between the earliest and most recent cohort (49.4 years (range, 20.1-68) versus 59.3 years (range, 18.1-78.1). Increasing number of patients with a Karnofsky performance status <90 underwent transplant over time. Increased utilisation of matched unrelated donors was apparent (<2006, 22.5% versus 2015-18, 45.2%; p < 0.001). Decreased use of myeloablative conditioning, increased use of busulphan-based platforms and anti-thymocyte globulin was evident. Of note, rates of acute (a)GVHD grade II-IV by day +100 decreased over time (p = 0.027) as did rates of chronic (c) GVHD, predominantly extensive cGVHD (<2006, 36% (31-41%) versus 2015-18, 23% (21-25%); p = 0.001). Overall, significant factors associated with worse overall survival and non-relapse mortality (NRM) remained older age, use of donors other than matched sibling, recipient CMV seropositivity and a lower Karnofsky performance status (<90). Multivariable analysis demonstrated improvements in overall survival and reductions in relapse risk over time with stable NRM rates despite increasing numbers of older, less fit patients and use of unrelated donors.

Beta-2-microglobulin level predicts outcome following autologous hematopoietic stem cell transplantation in patients with multiple myeloma.

Despite the widespread use of high-dose therapy combined with autologous hematopoietic stem cell transplantation (autoHSCT), the outcomes of multiple myeloma (MM) treatment remain variable. The aim of this study was to define pretransplantation factors that influence outcomes following autoHSCT in patients with MM. Eighty-one MM patients, aged 51 years (range 31-70 years), undergoing first autoHSCT were included in the analysis. Thirty patients were in complete remission and 51 were in partial remission. The conditioning regimen was based mainly on melphalan (200 mg/m(2) intravenous [iv]). The following factors were tested for their prognostic significance: beta-2-microglobulin (B2M), lactate dehydrogenase, monoclonal protein level, bone marrow plasma cell percentage (PL), hemoglobin level, age, interval from diagnosis to autoHSCT, and number of transplanted CD34-positive cells. The transplant-related mortality at day 100 was 3.7% (3/81). The incidence of progression at 9.2 years was 71% for patients with elevated B2M, and 32% for those where B2M was within normal limits (P = .02.) The probability of PFS was decreased for patients with B2M > or = versus < normal limits (29% vs 68%; P = .02) and PL > or = versus < 5% (0% vs 45%; P = 0.03). In a multivariate analysis B2M remained the only factor associated with increased risk of progression (relative risk [RR] = 3.3; P = .03) and reduced probability of PFS (RR = 3.3; P = .03). We concluded that B2M level measured at first autoHSCT was a useful predictor for progression and PFS in MM patients.

Use of G-CSF to hasten neutrophil recovery after auto-SCT for AML is not associated with increased relapse incidence: a report from the Acute Leukemia Working Party of the EBMT.

Application of G-CSF in AML is controversial as leukemic blasts may express receptors interacting with the cytokine, which may stimulate leukemia growth. We retrospectively analyzed the impact of G-CSF use to accelerate neutrophil recovery after auto-SCT on outcome. Adults with AML in first CR autografted between 1994 and 2010 were included. Nine hundred and seventy two patients were treated with G-CSF after auto-SCT whereas 1121 were not. BM and PB were used as a source of stem cells in 454 (22%) and 1639 (78%) cases, respectively. The incidence of relapse at 5 years in the BM-auto-SCT group was 38% for patients receiving post-transplant G-CSF and 43% for those not treated with G-CSF, P=0.46. In the PB-auto-SCT cohort, respective probabilities were 48% and 49%, P=0.49. No impact of the use of G-CSF could be demonstrated with respect to the probability of leukemia-free survival: in the BM-auto-SCT group, 51% for G-CSF(+) and 48% for G-CSF(-), P=0.73; in PB-auto-SCT group, 42% for G-CSF(+) and 43% for G-CSF(-), P=0.83. Although G-CSF administration significantly shortened the neutropenic phase, no beneficial effect was observed with regard to non-relapse mortality. In patients with AML, the use of G-CSF after auto-SCT is not associated with increased risk of relapse irrespective of the source of stem cells used.

Intermediate-dose Ara-C plus G-CSF for stem cell mobilization in patients with lymphoid malignancies, including predicted poor mobilizers.

The optimal protocol for mobilization of hematopoietic stem cells in patients with lymphoid malignancies has not been determined so far. We retrospectively analyzed the efficacy and safety of Ara-C at a dose of 1.6 g/m(2) compared with CY at a dose of 4.0 g/m(2), both combined with filgrastim. Seventy and forty-five patients, respectively, were included, among whom 60% were defined as 'predicted poor mobilizers'. The use of Ara-C was associated with significantly higher peak number of circulating CD34(+) cells compared with CY (P<0.0001). In the Ara-C group, 95% of patients with multiple myeloma (MM) collected at least 5 × 10(6) CD34(+) cells/kg required for tandem transplantation, and 97% of lymphoma patients collected at least 2 × 10(6) CD34(+) cells/kg, needed for a single autologous hematopoietic SCT (autoHSCT), which was achieved with a single leukapheresis in 91% of cases. Results for the CY group were significantly inferior (P<0.0001). No patient mobilized with Ara-C experienced febrile neutropenia, whereas 35% required platelet transfusions. Among patients who proceeded to autoHSCT, the time of both neutrophil and platelet recovery was significantly shorter for those mobilized with Ara-C than CY. We conclude that intermediate-dose Ara-C+filgrastim is a very effective and relatively safe mobilization protocol for patients with lymphoid malignancies.

Sequential recovery of NK cell receptor repertoire after allogeneic hematopoietic SCT.

Alloreactivity of natural killer (NK) cells contributes to the GVL reaction after allogeneic hematopoietic SCT (allo-HSCT). However, various procedure-related factors may affect NK cell maturation and their ability to recognize and kill leukemic cells. In this study, we prospectively evaluated expression of NK cell inhibitory receptors in 83 adults treated with myeloablative, killer cell Ig-like receptor (KIR)-ligand-matched allo-HSCT. NK cell maturation was evaluated by comparing the phenotypic patterns after allo-HSCT with the donor ones. The frequencies of KIR3DL1 were comparable to the donor ones on day +28, while they decreased significantly starting from day +100. The expression of KIR2DL2/3 was significantly lower in patients compared with donors up to day +100. The expression of KIR2DL1, despite continues growth, remained significantly decreased for 1 year after allo-HSCT. NKG2A was over-expressed up to day +180. Within 1 year after allo-HSCT, the NK cell phenotypic pattern tended to recapitulate the donor type. The process was disturbed by the use of steroids with significant differences observed on days +56 (P=0.01) and +100 (P=0.04). Up to day +100, reconstitution of NK cell receptor repertoire correlated with the absolute numbers of circulating CD3(+), CD3(+)CD4(+) and CD3(+)CD8(+) cells. Our observations should be taken into account when trying to predict potential benefit from NK cell alloreactivity.

Status of minimal residual disease determines outcome of autologous hematopoietic SCT in adult ALL.

The role of autologous hematopoietic SCT (autoHSCT) in the treatment of high-risk (HR) adult ALL is controversial. In this study, we retrospectively analyzed the results of autoHSCT according to the status of minimal residual disease (MRD) at transplantation, as a joint analysis of the European Study Group for Adult ALL (EWALL). Data on 123 recipients of autoHSCT, aged 31 (16-59) years, with B-lineage (n=77) or T-lineage (n=46) ALL were included. In a cohort of Ph-negative ALL, the probability of leukemia-free survival at 5 years was higher for patients with MRD <0.1% compared with those with MRD > or = 0.1% (57 vs 17%, P=0.0002). The difference was significant for T-lineage ALL (62 vs 8%, P=0.001), and a tendency was observed for B-lineage ALL (54 vs 26%, P=0.17). In a multivariate analysis, adjusted for other potential prognostic factors, high MRD level remained the only independent factor associated with increased risk of failure (risk ratio, 2.8; P=0.0005). We conclude that MRD determines the outcome of autoHSCT in HR adult ALL. Our results suggest the need to reevaluate the role of this treatment option in prospective trials.