Donor-Type Myelodysplastic Syndrome with t(2;3) and Monosomy 7 after Allogeneic Peripheral Blood Stem Cell Transplantation and Liver Transplantation in a Patient with Severe-Type Aplastie Anemia

Hypothesis: can transfer of primary neoplasm-derived extracellular vesicles and mitochondria contribute to the development of donor cell-derived hematologic neoplasms after allogeneic hematopoietic cell transplantation?

Allogeneic hematopoietic cell transplantation (allo-HCT) is an essential treatment option for various neoplastic and non-neoplastic hematologic diseases. Although its efficacy is modest, a significant proportion of patients experience relapse, graft-versus-host disease, infection or impaired hematopoiesis. Among these, the most frequent cause of post-transplant mortality is relapse, whereas the development of de novo hematologic neoplasms from donor cells after allo-HCT occurs on some occasion as a rare complication. The mechanisms involved in the pathogenesis of the de novo hematologic neoplasms from donor cells are complex, and a multifactorial process contributes to the development of this complication. Recently, extracellular vesicles, particularly exosomes, and mitochondria have been shown to play crucial roles in intercellular communication through the transfer of specific constituents, such as deoxyribonucleic acids, ribonucleic acids, lipids, metabolites and cytosolic and cell-surface proteins. Here, I discuss the potential causative roles of these subcellular components in the development of de novo hematologic neoplasms from donor cells after allo-HCT, in addition to other etiologies.

Lessons Learned from Donor Cell-Derived Myeloid Neoplasms: Report of Three Cases and Review of the Literature

Donor-cell derived myeloid neoplasm (DDMN), a rare complication after allogeneic hematopoietic cell transplantation (HCT), is of interest for its potential to reveal donor-derived and host-derived factors that contribute to the pathogenesis of leukemia. The accurate diagnosis of donor-derived leukemias has been facilitated by the more frequent use of molecular techniques. In this study, we describe three additional cases of DDMN; the first reported case of donor-derived chronic myelomonocytic leukemia (CMML), one acute myeloid leukemia (AML) with t(8;21)(q22;22); RUNX1-RUNX1T1 and one donor-derived MDS with deletion 5q. A review of the cytogenetic profiles of previously reported DDMN indicates a significant contribution of therapy-related myeloid neoplasms. Cases with direct evidence of donor- or recipient-dependent factors are rare; a role of direct transfer of leukemic cells, genomic instability of the donor, abnormal gene methylation in donor cells, proleukemic potential of abnormal stromal niche, and the role of immunological surveillance after transplantation has been observed. The role of additional potential pathogenetic factors that are without clinically observed evidence are also reviewed.

Genetics of donor cell leukemia in acute myelogenous leukemia and myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplantation (HSCT) is an important therapeutic modality for patients with acute myelogenous leukemia (AML) with poor risk features. Nonetheless, roughly 30% of such patients have leukemia recurrence and up to 2% of these are donor-derived leukemias, in which malignancy develops in the donor's transplanted cells, despite extremely low rates of leukemia in the donors themselves. Notably, over 20% of these malignancies carry chromosome 7 abnormalities nearly all of which are monosomies. Recent advances in whole exome and genome sequencing have allowed for detection of candidate genes that likely contribute to the development of AML in donor cells (donor leukemia, DCL). These genes include CEBPA, GATA2, JAK2, RUNX1, DDX41, EZH2, IDH1/2, DNMT3A, ASXL1, XPD, XRCC3, and CHEK1. The potential roles of variants in these genes are evaluated based on familial clustering of MDS/AML and corresponding animal studies demonstrating their leukemogenic nature. This review describes the spectrum of genetic aberrations detected in DCL cases in the literature with regard to the character of the individual cases, existing family cohorts that carry individual genes, and functional studies that support etiologic roles in AML development. DCL presents a unique opportunity to examine genetic variants in the donors and recipients with regards to progression to malignancy.

Leukemic Transformation of Severe Aplastic Anemia Following Matched Allogenic Stem Cell Transplantation, Transplanted Again in CR 1

Aplastic anemia (AA) is a life-threatening bone marrow failure disorder, if untreated, is associated with very high mortality. Allogenic bone marrow transplantation (BMT) is the standard of care for severe aplastic anemia (SAA) patients those who are younger than 40 years of age. The development of secondary malignancies in post-BMT setting for AA is a rare, however, well documented phenomenon. Among the secondary malignancies, development of acute myeloid leukemia is even rarer entity. Here we report a case of acute myeloid leukemia following human leucocyte antigen (HLA) matched sibling peripheral blood stem cell transplant (PBSCT) in a case of SAA. The patient achieved complete remission (CR) following chemotherapy and in CR1, a second HLA matched PBSCT from a different donor was offered. The patient is presently in remission at day +180 post-PBSCT.

Development of donor cell leukemia following peripheral blood stem cell transplantation for severe aplastic anemia: A case report

Donor cell leukemia (DCL) is a rare complication of hematopoietic stem cell transplantation (HSCT) which occurs in ~5% of all leukemic relapses. In the English literature, >60 cases of DCL have been reported, however, only two cases of DCL following HSCT for the treatment of severe aplastic anemia (SAA) have been described to date. In the present study, the case of a 25 year-old male patient diagnosed with SAA, who underwent a peripheral blood stem cell transplantation (PBSCT) using cells obtained from a sibling with an identical human leukocyte antigen, is presented. The patient developed acute myeloid leukemia with an (8;21)(q22;q22) translocation and an extra copy of the chromosome 8 in donor cells 2.5 years following PBSCT, which was preceded by the development of Graves' disease 1 year following PBSCT. The leukemia achieved complete remission following 1 cycle of priming therapy, 2 cycles of consolidation chemotherapy with daunorubicin and cytarabine and maintenance therapy with interleukin-2 (IL-2). At present, the patient has discontinued IL-2 therapy, and the DCL has been in molecular remission for >3 years. The present case indicates that chemotherapy and IL-2 maintenance therapy are an effective treatment for DCL; hyperthyroidism was relieved following treatment, although hypothyroidism subsequently developed.

Monosomy 7 in donor cell-derived leukemia after bone marrow transplantation for severe aplastic anemia: Report of a new case and review of the literature

Monosomy 7 arises as a recurrent chromosome aberration in donor cell leukemia after hematopoietic stem cell transplantation. We report a new case of donor cell leukemia with monosomy 7 following HLA-identical allogenic bone marrow transplantation for severe aplastic anemia (SAA). The male patient received a bone marrow graft from his sister, and monosomy 7 was detected only in the XX donor cells, 34 months after transplantation. The patient’s bone marrow microenvironment may have played a role in the leukemic transformation of the donor hematopoietic cells.

Donor cell-derived leukemias/myelodysplastic neoplasms in allogeneic hematopoietic stem cell transplant recipients: a clinicopathologic study of 10 cases and a comprehensive review of the literature

We report 10 cases of donor cell leukemia (DCL). All cases except the case of chronic lymphocytic leukemia had anemia, neutropenia, and/or thrombocytopenia when DCL was diagnosed. Eight cases with sex-mismatched hematopoietic stem cell transplant (HCT) showed donor gonosomal complements, suggesting DCL. Clonal cytogenetic abnormalities were detected in 8 cases: 6 were monosomy 7/del(7q). In all 10 cases, engraftment studies confirmed donor cell origin. Retrospective fluorescence in situ hybridization in archived donor cells in 4 cases showed a low level of abnormalities in 2. Of 7 patients with clinical follow-up of 5 months or more, 1 (with acute myeloid leukemia) died of disease; 6 are alive, including 1 with myelodysplastic syndrome with spontaneous remission. Similar to reported cases, we found disproportional sex-mismatched HCTs, suggesting probable underdetection of DCL in sex-matched HCTs. The latency between HCT and DCL ranged from 1 to 193 months (median, 24 months), in keeping with the literature. Analyzing our cases, pooled with reported cases, with survival models showed much shorter latency for malignancy as primary disease, for T-cell large granular lymphocyte leukemia as type of DCL, and for umbilical cord blood as stem cell source.

Donor cell leukemia: a review

Relapse of acute leukemia following hematopoietic stem cell transplantation (HSCT) usually represents return of an original disease clone, having evaded eradication by pretransplant chemo-/radiotherapy, conditioning, or posttransplant graft-versus-leukemia (GVL) effect. Rarely, acute leukemia can develop de novo in engrafted cells of donor origin. Donor cell leukemia (DCL) was first recognized in 1971, but for many years, the paucity of reported cases suggested it to be a rare phenomenon. However, in recent years, an upsurge in reported cases (in parallel with advances in molecular chimerism monitoring) suggest that it may be significantly more common than previously appreciated; emerging evidence suggests that DCL might represent up to 5% of all posttransplant leukemia "relapses." Recognition of DCL is important for several reasons. Donor-derivation of the leukemic clone has implications when selecting appropriate therapy, because seeking to enhance an allogeneic GVL effect would intuitively not have the same role as in standard recipient-derived relapses. There are also broader implications for donor selection and workup, particularly given the growing popularity of nonmyeloblative HSCT and corresponding rising age of the potential donor pool. Identification of DCL raises potential concerns over future health of the donor, posing ethical dilemmas regarding responsibilities toward donor notification (particularly in the context of cord blood transplantation). The entity of DCL is also of research interest, because it might provide a unique human model for studying the mechanisms of leukemogenesis in vivo. This review presents and collates all reported cases of DCL, and discusses the various strategies, controversies, and pitfalls when investigating origin of posttransplant relapse. Putative etiologic factors and mechanisms are proposed, and attempts made to address the difficult ethical questions posed by discovery of donor-derived malignancy within a HSCT recipient.