Myelodysplasia in younger adults: outlier or unique molecular entity?

Pilot Study of Donor-Engrafted Clonal Hematopoiesis Evolution and Clinical Outcomes in Allogeneic Hematopoietic Cell Transplantation Recipients Using a National Registry

Improved treatment options, such as reduced-intensity conditioning (RIC), enable older patients to receive potentially curative allogeneic hematopoietic cell transplantation (HCT). This progress has led to increased use of older HLA-matched sibling donors. An unintended potential risk associated with older donors is transplantation of donor cells with clonal hematopoiesis (CH) into patients. We aimed to determine the prevalence of CH in older HLA-matched sibling donors pretransplantation and to assess the clinical impact of donor-engrafted CH on HCT outcomes. This was an observational study using donor peripheral blood samples from the Center for International Blood and Marrow Transplant Research repository, linked with corresponding recipient outcomes. To explore engraftment efficiency and evolution of CH mutations following HCT, recipient follow-up samples available through the Bone Marrow Transplant Clinical Trials Network (Protocol 1202) were included. Older donors and patients (both ≥55 years) receiving first RIC HCT for myeloid malignancies were eligible. DNA from archived donor blood samples was used for targeted deep sequencing to identify CH. The associations between donor CH status and recipient outcomes, including acute graft-versus-host disease (aGVHD), chronic GVHD (cGVHD), overall survival, relapse, nonrelapse mortality, disease-free survival, composite GVHD-free and relapse-free survival, and cGVHD-free and relapse-free survival, were analyzed. A total of 299 donors were successfully sequenced to detect CH. At a variant allele frequency (VAF) ≥2%, there were 44 CH mutations in 13.7% (41 of 299) of HLA-matched sibling donors. CH mostly involved DNMT3A (n = 27; 61.4%) and TET2 (n= 9; 20.5%). Post-HCT samples from 13 recipients were also sequenced, of whom 7 had CH+ donors. All of the donor CH mutations (n = 7/7; 100%) were detected in recipients at day 56 or day 90 post-HCT. Overall, mutation VAFs remained relatively constant up to day 90 post-HCT (median change, .005; range, -.008 to .024). Doubling time analysis of recipient day 56 and day 90 data showed that donor-engrafted CH mutations initially expand then decrease to a stable VAF; germline mutations had longer doubling times than CH mutations. The cumulative incidence of grade II-IV aGVHD at day 100 was higher in HCT recipients with CH+ donors (37.5% versus 25.1%); however, the risk for aGVHD by donor CH status did not reach statistical significance (hazard ratio, 1.35; 95% confidence interval, .61 to 3.01; P = .47). There were no statistically significant differences in the cumulative incidence of cGVHD or any secondary outcomes by donor CH status. In subset analysis, the incidence of cGVHD was lower in recipients of grafts from DNMT3A CH+ donors versus donors without DNMT3A CH (34.4% versus 57%; P = .035). Donor cell leukemia was not reported in any donor-recipient pairs. CH in older HLA-matched sibling donors is relatively common and successfully engrafts and persists in recipients. In a homogenous population (myeloid malignancies, older donors and recipients, RICr, non-cyclophosphamide-containing GVHD prophylaxis), we did not detect a difference in cGVHD risk or other secondary outcomes by donor CH status. Subgroup analyses suggest potential differential effects by clinical characteristics and CH mutations. Larger prospective studies are needed to robustly determine which subsets of patients and CH mutations elicit meaningful impacts on clinical outcomes.

Genome-wide analysis toward the epigenetic aetiology of myelodysplastic syndrome disease progression and pharmacoepigenomic basis of hypomethylating agents drug treatment response

Myelodysplastic syndromes (MDS) consist of a group of hematological malignancies characterized by ineffective hematopoiesis, cytogenetic abnormalities, and often a high risk of transformation to acute myeloid leukemia (AML). So far, there have been only a very limited number of studies assessing the epigenetics component contributing to the pathophysiology of these disorders, but not a single study assessing this at a genome-wide level. Here, we implemented a generic high throughput epigenomics approach, using methylated DNA sequencing (MeD-seq) of LpnPI digested fragments to identify potential epigenomic targets associated with MDS subtypes. Our results highlighted that PCDHG and ZNF gene families harbor potential epigenomic targets, which have been shown to be differentially methylated in a variety of comparisons between different MDS subtypes. Specifically, CpG islands, transcription start sites and post-transcriptional start sites within ZNF124, ZNF497 and PCDHG family are differentially methylated with fold change above 3,5. Overall, these findings highlight important aspects of the epigenomic component of MDS syndromes pathogenesis and the pharmacoepigenomic basis to the hypomethylating agents drug treatment response, while this generic high throughput whole epigenome sequencing approach could be readily implemented to other genetic diseases with a strong epigenetic component.

Incidence of Acute Myeloid Leukemia and Myelodysplastic Syndrome in Patients With Inflammatory Bowel Disease and the Impact of Thiopurines on Their Risk

INTRODUCTION

Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) are rare myeloid clonal disorders that commonly affect the elderly population and have poor prognosis. There are limited data on the risk of AML/MDS among patients with inflammatory bowel disease (IBD), especially on the impact of thiopurines (TPs).

METHODS

We conducted a retrospective cohort study among patients with IBD from Veteran Affairs data set. The exposure of interest was TP exposure: (i) never exposed to TPs, (ii) past TP use (discontinued >6 months ago), (iii) current TP use with a cumulative exposure of <2 years, and (iv) current TP use with a cumulative exposure of ≥2 years. The outcome of interest was a composite outcome of incident diagnosis of AML and/or MDS. Cox regression was used to estimate the adjusted and unadjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for AML/MDS risk associated with TP use defined as a time-varying exposure.

RESULTS

Among 56,314 study patients, 107 developed AML/MDS. The overall incidence of AML/MDS in the IBD population was 18.7 per 100,000 patient-years. The incidences among those never exposed to TPs, past users of TPs, current users of TPs with a cumulative exposure of <2 years, and current users of TPs with a cumulative exposure of ≥2 years were 17.0, 17.7, 30.4, and 30.3 per 100,000 patient-years, respectively. In multivariable Cox regression analysis, compared with never exposed to TPs, current use of TPs was associated with increased risk (adjusted HR 3.05; 95% CI 1.54-6.06, P = 0.0014 for current use of TPs with a cumulative exposure of <2 years and adjusted HR 2.32; 95% CI 1.22-4.41, P = 0.0101 for current use of TPs with a cumulative exposure of ≥2 years), whereas past TP exposure was not.

DISCUSSION

Among patients with IBD, current TP use was associated with an increased risk of AML/MDS, which reverts to baseline after discontinuation of TP use.