Reduced-Intensity Allogeneic Hematopoietic Stem Cell Transplant For GATA2 Deficiency

Heterozygous sporadic or inherited mutations in the GATA2 gene result in a syndrome known variably as: “MonoMAC” for monocytopenia with nontuberculous mycobacterial (NTM) infections; DCML, dendritic cell, monocyte and lymphoid cell deficiency; Emberger's syndrome, lymphedema and MDS with monosomy 7; and familial myelodysplastic syndrome (MDS)/acute myelogenous leukemia (AML). Life-threatening opportunistic infections and myeloid transformation constitute the rationale for allogeneic hematopoietic stem cell transplant (HSCT) for GATA2 deficiency.

We treated 14 patients with GATA2 deficiency using a nonmyeloablative-conditioning regimen and matched related donors (MRD) (n=4), matched unrelated donors (URD) (n=4), umbilical cord blood (UCB) (n=4), and haploidentical related donor (HD) (n=2) sources. There was considerable pre-transplant morbidity in this cohort of patients. MRD and URD recipients received 200 cGy of total body irradiation (TBI) and 3 days of fludarabine; UCB recipients received 200cGy TBI, cyclophosphamide 50 mg/kg on day -6, and 5 days of fludarabine; HD recipients received 200cGy TBI, cyclophosphamide 14.5 mg/kg on days -6 and -5, and fludarabine for 5 days. MRD, URD, and UCB recipients received tacrolimus and sirolimus for GVHD prophylaxis. HD recipients received cyclophosphamide 50 mg/kg on days + 3 and +4 followed by tacrolimus and mycophenolate mofetil. MRD and URD donor recipients received peripheral blood stem cells (PBSC) and HD donor recipients received bone marrow stem cells.

(table 1): The median follow-up in the MRD cohort was 32 months, excluding one early death in a patient on a ventilator at the time of transplant. One patient relapsed one year post-transplant and required re-transplant using a myeloablative regimen. All 4 patients in this cohort developed acute GVHD. In the URD cohort, all patients are alive, however one patient rejected the PBSC graft and required a second URD transplant from a different donor. Two patients developed acute GVHD. In the UCB cohort, there was one early death from sepsis, one graft rejection, and one donor cell leukemia that occurred 2.5 years post-transplant. The remaining patient had a complicated course, but at 3 years post-transplant he is fully engrafted, on no medications, and has no GVHD. In the two patients who received HD transplants, one had progressed to proliferative CMML prior to transplant and died in the immediate post-transplant period. The second patient engrafted and is doing well two months post-transplant with resolution of an EBV-driven T cell lymphoma. All patients who engrafted had complete reconstitution of the monocyte, NK, and B lymphocyte compartments; all had correction of the underlying myeloid malignancy, and reversal of the infection susceptibility phenotype, characteristic of the disease. In particular, there were no recurrences of NTM.

Nonmyeloablative HSCT in GATA2 deficiency results in reconstitution of the severely deficient monocyte, B and NK cell populations and correction of the infection susceptibility phenotype. However, 1 of 4 MRD recipients developed a relapse of the original clone, and 1 of 4 URD recipients rejected the donor PBSC. The incidence of relapse and rejection, as well as the unfavorable cytogenetics in many patients, suggests that a more intense conditioning regimen is required to treat these patients. In this regard, we are now using a myeloablative regimen with busulfan and fludarabine. The poor outcome with UCB in this cohort of immunocompromised patients supports the use of HD transplants when a MRD or URD is not available. We anticipate that with increasing use of genetic testing for GATA2 mutations, patients will be transplanted earlier in the course of disease, before significant organ damage or clonal evolution of MDS to AML and CMML occurs, and that the outcome of allogeneic HSCT in these patients will continue to improve with these modifications in the transplant approach.

No relevant conflicts of interest to declare.