Time to engraftment following allogeneic stem cell transplantation is significantly longer in patients with myelodysplastic syndrome than with acute myeloid leukemia

Characterization of engraftment dynamics in myelofibrosis after allogeneic hematopoietic cell transplantation including novel conditioning schemes

Introduction

Myelofibrosis (MF) is a rare hematopoietic stem cell disorder progressing to bone marrow (BM) failure or blast phase. Allogeneic hematopoietic cell transplantation (HCT) represents a potentially curative therapy for a limited subset of patients with advanced MF, who are eligible, but engraftment in MF vs. AML is delayed which promotes complications. As determinants of engraftment in MF are incompletely characterized, we studied engraftment dynamics at our center.

Methods

A longitudinal cohort of 71 allogeneic HCT performed 2000-2019 with >50% after 2015 was evaluated.

Results

Median time to neutrophil engraftment ≥0.5x109/l was +20 days post-transplant and associated with BM fibrosis, splenomegaly and infused CD34+ cell number. Engraftment dynamics were similar in primary vs. secondary MF and were independent of MF driver mutations in JAK2, CALR and MPL. Neutrophil engraftment occurred later upon haploidentical HCT with thiotepa-busulfan-fludarabine conditioning, post-transplant cyclophosphamide and G-CSF (TBF-PTCy/G-CSF) administered to 9.9% and 15.6% of patients in 2000-2019 and after 2015, respectively. Engraftment of platelets was similarly delayed, while reconstitution of reticulocytes was not affected.

Conclusions

Since MF is a rare hematologic malignancy, this data from a large number of HCT for MF is essential to substantiate that later neutrophil and platelet engraftment in MF relates both to host and treatment-related factors. Observations from this longitudinal cohort support that novel conditioning schemes administered also to rare entities such as MF, require detailed evaluation in larger, multi-center cohorts to assess also indicators of long-term graft function and overall outcome in patients with this infrequent hematopoietic neoplasm undergoing allogeneic transplantation.

Evaluation of a primary antifungal prophylaxis protocol for preventing invasive mold infections after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Invasive mold infections contribute to morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation. The optimal strategy for primary antifungal prophylaxis in this patient population remains uncertain.

METHODS

Medical records of patients who underwent allogeneic hematopoietic stem cell transplantation between 1 January 2013 and 31 December 2017 were retrospectively reviewed. Adult patients were included if they received micafungin followed by fluconazole, with the option to escalate to voriconazole, for antifungal prophylaxis. The primary outcome was the incidence rate of proven or probable invasive mold infection. Secondary outcomes were time to invasive mold infection diagnosis, invasive mold infection-related mortality, and risk factors associated with invasive mold infection.

RESULTS

Two hundred patients were included in the study, a majority of whom underwent matched unrelated (46%) or matched related (33%) donor transplants. The incidence rate of proven or probable invasive mold infection was 18.4 cases per 100 patient-years, with a one-year cumulative incidence of 14%. Median time to proven or probable invasive mold infection was 94 days post-transplant (IQR 26-178), with invasive mold infection-related mortality occurring in 18 (64%) of 28 patients diagnosed with invasive mold infection. Comparison of invasive mold infection-free survival by potential risk factors failed to show any significant differences.

CONCLUSIONS

In this real-life cohort of allogeneic hematopoietic stem cell transplantation recipients, the incidence of proven or probable invasive mold infection was higher than expected based on previous literature. In the absence of standard guidance on anti-mold prophylaxis in this patient population and given that unique risk factors for invasive mold infection may differ between institutions, it is essential that centers performing allogeneic hematopoietic stem cell transplantation routinely monitor their antifungal prophylaxis strategies for effectiveness.

No telomere shortening in marrow stroma from patients with MDS

Telomere shortening with age may lead to genomic instability and an increased risk of cancer. Given the role of the microenvironment in the pathophysiology of the myelodysplastic syndrome (MDS), primarily a disease of older age, we determined telomere length in primary cultured marrow stroma cells using quantitative fluorescent in situ hybridization (qFISH) and quantitative polymerase chain reaction (qPCR). qFISH showed comparable rates of decrease in telomere length with age in MDS patients and age-matched healthy controls. Telomere length assessment by qPCR showed similar results. These findings suggest a lack of significant differences between MDS patients and healthy controls in terms of telomere stability in marrow stroma in contrast to that observed in hematopoietic cells. In conclusion, this demonstrates that, although MDS stroma cells and hematopoietic cells share the same microenvironment, the stromal cells do not share the processes that contribute to accelerated telomere attrition, suggesting that stromal cell proliferative potential is not limiting in MDS.

Comorbidity predicts survival in myelodysplastic syndromes or secondary acute myeloid leukaemia after allogeneic stem cell transplantation

BACKGROUND

Recent data suggest that, among other factors, comorbidity may be an important prognostic variable in patients with myelodysplastic syndromes (MDS) who are eligible for haematopoietic stem cell transplantation (SCT).

PATIENTS AND METHODS

We examined the overall survival (OS) and underlying risk factors in 45 adult patients with MDS (n = 38), chronic myelomonocytic leukaemia (n = 1), or secondary acute myeloid leukaemia (AML) arising from MDS (n = 6), who underwent allogeneic SCT at our Institution.

RESULTS

With a median follow-up of 37 months, OS for all patients was 23%, post-transplant relapse occurred in 11 patients, and 10 patients died from treatment-related complications. The overall outcome and survival was independent of cytogenetic abnormalities and International Prognostic Scoring System (IPSS). However, we identified comorbidity as defined by the haematopoietic cell transplantation specific comorbidity index (HCT-CI), as a significant adverse prognostic variable in our MDS patients.

CONCLUSIONS

Based on these data and similar published data we recommend selecting patients with MDS or secondary AML for SCT according to the presence of comorbidities.

Treosulfan/fludarabine as an allogeneic hematopoietic stem cell transplant conditioning regimen for high-risk patients

In recent years, new conditioning regimens have been explored in patients not eligible for conventional transplant with the aim to reduce transplant-related mortality. In a phase II multicentric prospective trial, we investigated the safety and feasibility of the treosulfan-fludarabine combination prior to allogeneic hematopoietic stem cell transplant in patients with various hematological malignancies not eligible for conventional regimens because of previous intensive treatment, older age, and comorbidities. Forty-six consecutive patients, median age 48 years (range 17-69), were enrolled. Sixteen of them were in complete remission, and 20 had a HSCT comorbidity index > or = 1. Forty-four patients had regular and sustained engraftment, and 39 out of 40 evaluable patients developed complete chimerism. Nonhematological toxicity was limited. Risk of transplant-related mortality was 9% (95% CI, 2-17%) at day +100 and plotted at 15% (95% CI, 7-22%) after 7 months. The estimated overall survival and progression-free survival with a median follow-up of 20 months were 51% and 38%, respectively. The estimated 30 months progression-free survival for patients transplanted in remission was 56%. The treosulfan-fludarabine combination is a reduced-toxicity but myeloablative regimen that can be proposed to patients not fitting criteria for conventional transplant regimens. Longer follow-up and further prospective studies are necessary to evaluate this regimen.