Donor cell-derived acute myeloblastic leukemia after allogeneic peripheral blood hematopoietic stem cell transplantation for juvenile myelomonocytic leukemia

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.

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.

Donor cell-derived acute lymphocytic leukemia after allogeneic stem cell transplantation for multiple myeloma

Donor cell leukemia (DCL) is a rare, but well-known, complication after allogeneic hematopoietic cell transplantation. We report a case of donor cell-derived acute lymphocytic leukemia (ALL) occurring in a 55-year-old man after allogeneic bone marrow transplantation (allo-BMT) from an HLA-matched unrelated donor for refractory multiple myeloma (MM). Molecular analysis using short tandem repeat sequences proved the ALL to be of donor origin. He underwent combination chemotherapy and second allo-BMT from an alternative donor. After second allo-BMT, extramedullary myeloma relapsed as tumor, but was successfully treated with proteasome inhibitor, bortezomib. However, he died from severe graft-versus-host disease four months after the second transplantation. Although more than 50 cases of DCL have been reported, there have been only two reports of DCL developed in MM patients including our case. This rare complication may give some insights into leukemogenesis.

Donor cell leukemia after allogeneic peripheral blood stem cell transplantation: a case report and literature review

A 49-year-old male developed recurrent acute myeloid leukemia 27 months after allogeneic peripheral blood stem cell transplantation (PBSCT) from an HLA-identical brother. The immunophenotype of the blastic cell population was incompatible with that of the pre-transplant blast cells; a mutation in C/EBPA gene was found in the pre-transplant blast cells that was not present in the post-transplant blast cells, and short tandem repeat analysis of marrow cells, which included 71% blasts, showed complete donor chimera. Thus, this recipient developed donor cell leukemia (DCL). The donor was healthy when DCL developed in the recipient as well as before donation of the peripheral blood stem cells. Only five cases of DCL after PBSCT have been reported in the literature. As a mechanism for the development of DCL, a vigorous proliferative demand on the donor cells, which often correlates with a higher likelihood of replication error or mutation, has been proposed. Peripheral blood stem cells might have an advantage in that they are associated with a low incidence of DCL development because PBSCT recipients receive a higher total cell dose than recipients of bone marrow or cord blood cells.