In vivo T-depleted reduced-intensity transplantation for GATA2-related immune dysfunction

To the editor:

Germ line heterozygous GATA2 mutation causes failure of mononuclear cell development, immune dysfunction, and evolution to myeloid neoplasia.^1-4  Symptoms may arise at almost any age, reaching a penetrance of 90% in the seventh decade.³  Fatal complications include mycobacterial infection, uncontrolled herpesvirus infection, human papillomavirus (HPV)–associated carcinoma, and hematologic transformation.^1-4  Bone marrow transplantation is curative, but the optimal timing and protocol remain undefined.^4-11  Patients who develop GATA2-related myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) have received successful transplantations with myeloablative and reduced-intensity conditioning that followed standard clinical algorithms for hematologic malignancy.^2-4  However, 21% to 60% of GATA2 patients do not present with MDS or AML^2,3  and may suffer severe infectious complications, including significant pulmonary dysfunction. The optimal therapy for this group remains undefined.^8,9 

Here we present a retrospective analysis of 4 patients who had successful transplants with a T-cell–depleted reduced-intensity regimen for predominantly infectious and respiratory complications of GATA2 mutation. Our cohort included consecutive patients who received transplants at 2 United Kingdom centers (Manchester and Newcastle) and had at least 2 years of follow-up (2008-2012). Their laboratory indices have been previously described^2,12,13  and are summarized in supplemental Table 1 (available on the Blood Web site). Patients 1 to 3 had grossly elevated fms-like tyrosine kinase-3 (flt3) ligand and a severe dendritic cell, monocyte, and lymphocyte deficiency phenotype with relatively well-preserved hemoglobin, neutrophils, and platelets. Patient 4 had monocytopenia in the context of more conventional MDS with anemia, thrombocytopenia, and mildly elevated flt3 ligand. GATA2 mutation and clinical features are summarized in Table 1. The interval between presentation and transplantation was 1 to 8 years, and the age at transplantation was 16 to 35 years. Patients 2 to 4 had a family history of GATA2-related disease. Patients 1 to 3 had experienced severe infection. Patient 1 had a Bacille Calmette-Guérin infection. Patient 2 had pulmonary Pseudomonas aeruginosa and methicillin-resistant S aureus infection along with a genital HPV infection, which caused grade 3 VIN. Patient 3 had a Mycobacterium malmoense infection (Figure 1). Patients 2 to 4 had moderate to severe respiratory compromise as a result of PAP or emphysema. At the time of transplantation, patients 1 and 3 were receiving antimycobacterial therapy. Patient 2 required continuous oxygen and noninvasive ventilation at night and had been scheduled for radical surgical resection of advanced VIN. Patient 3 had a history of granulomatous hepatitis and Addison disease that may have been attributable to GATA2 mutation.¹⁴  For all patients, bone marrow examination was relatively unremarkable with normal cytogenetics and no excess of blasts. Patients 1 to 3 were hypocellular with small hypolobulated megakaryocytes, mild increases in reticulin, and scattered noncaseating granulomata (Figure 1A). Only patient 4 had clear evidence of trilineage dysplasia but no excess of blasts. A bone marrow examination 8 years previously had been reported as normal. Both patients 2 and 4 had acquired an ASXL1 mutation at the time of transplantation. Patient 2 had delivered her first child prematurely at 28 week’s gestation.

Details regarding transplantation are summarized in Table 1. All patients received 5 doses of fludarabine 30 mg/m² days −7 to −3 or days −6 to −2 and an alkylating agent such as melphalan 140 mg/m² day −2 or busulfan 3.2 mg/kg intravenously days −7 to −6 or treosulfan 14 mg/m² days −6 to −4. Choice of alkykator reflected unit practice and was not patient-specific. In vivo T-cell depletion with alemtuzumab was given at a total dose of 0.7 mg/kg to 1.2 mg/kg in 2 to 5 divided doses. Mobilized peripheral blood stem cell grafts were infused at a dose of 1.9 to 8.0 × 10⁶ CD34⁺ cells per kg supported with granulocyte colony-stimulating factor from day +6. All patients received cyclosporin as prophylaxis for GVHD. Patients 1 to 3 with unrelated donors also received mycophenolate mofetil 1g twice per day for 30 to 60 days posttransplant. All patients were discharged from the hospital between 14 and 33 days posttransplant. Three patients experienced grade 1 delayed acute GVHD (skin rash) during immunosuppression withdrawal but none required systemic therapy and none went on to develop chronic GVHD (Table 1). Patient 1 experienced an immune reconstitution syndrome of non-GVHD rash and fever in the first month (a common complication of bone marrow transplantation during active mycobacterial infection¹⁵ ) and required a short course of systemic corticosteroids. Idiopathic thrombocytopenic purpura was observed in patient 2 and hemolytic anemia was observed in patient 3 at 7 and 9 months posttransplant, respectively. These complications were observed in other patients who received transplants accompanied by fludarabine and alemtuzumab-based conditioning, and the complications resolved within 4 weeks after initiation of treatment with rituximab (375 mg/m² per week for 4 weeks). High levels of myeloid and T-cell chimerism were observed in all patients by 3 months (Figure 1B). B-cell chimerism was not routinely monitored. Patients 2 to 4 who had significant respiratory compromise showed a marked and sustained improvement within weeks of transplantation (Figure 1C). Continuous oxygen and noninvasive ventilation at night were rapidly withdrawn from patient 2 after dramatic radiologic improvement (Figure 1D). Antimycobacterial drugs were discontinued after transplantation in patients 1 and 3 within 1 year, when CD3 T cells had increased to more than 200/μL. Patient 3 and his donor were both seropositive for cytomegalovirus, and a short reactivation was treated uneventfully with oral valganciclovir. The other 3 patients received grafts from matched cytomegalovirus-negative donors. Patient 2 was vaccinated with bivalent HPV- 16/18 vaccine at 20, 21, and 26 months posttransplant and, strikingly, her HPV-associated grade 3 VIN completely regressed by 36 months. She subsequently had 2 successful full-term pregnancies. Patient 1 was diagnosed with malignant melanoma 3 years after transplantation, but this was fully resected without further evidence of disease. All patients are alive at between 5 and 9 years posttransplantation with Karnofsky performance status of 90% to 100%.

These cases illustrate that fludarabine-based reduced-intensity transplantation with alemtuzumab in vivo T-cell depletion is acceptable for patients with severe infectious and respiratory complications from GATA2 mutation. Alemtuzumab-based conditioning provided excellent control of GVHD, even with mismatched donors. Although it is surprising that GVHD occurs at all in the absence of recipient dendritic cells, monocytes, and B cells, it has been reported as a lethal complication in other series.^6,8,9,11  T-cell depletion was not problematic, and the rapid restoration of donor dendritic cells, monocytes, B cells, and natural killer cells led to a full recovery.

Life-threatening infection, severe respiratory compromise as a result of PAP, or both, were the major triggers for transplantation. In retrospect, it was discovered that 2 of the 4 patients had developed clonal hematopoiesis with ASXL1 mutation. Patients with both severe infection and myeloid neoplasia are especially challenging because reductions in conditioning intensity for infection-related comorbidity may compromise the durability of remission from MDS or AML. Relapses were observed in a previously reported cohort after nonmyeloablative conditioning with fludarabine and 2 Gy total body irradiation.⁸  Fludarabine combined with moderate-dose alkylating agents, as used here, has a track record in the transplantation of adults who have MDS or AML.^16,17  Our results suggest that this approach is a useful compromise for patients with uncontrolled infection and clonal hematopoiesis or early MDS. In females of reproductive age, fertility may already be compromised by preterm labor and cervical or vulval intraepithelial neoplasia.²  Transplantation may indeed improve their prospects, as in the case of patient 2.

In summarizing this experience, we propose that life-threatening complications of GATA2-related disease, including PAP, atypical mycobacterial infection, and advanced HPV-associated dysplasia should be considered as indications for transplantation, even in the absence of overt myeloid neoplasia. PAP responds poorly to conventional therapy with whole-lung lavage and granulocyte-macrophage colony-stimulating factor,¹⁸  but resolves within weeks of transplantation.⁵  Recurrent mycobacterial infection may exacerbate respiratory decline beyond the point of salvage if immune reconstitution is not provided. HPV-related intraepithelial neoplasia can lead to disfiguring surgery which may prove ineffective at preventing lethal metastatic disease.⁹  Detection of the accessory cellular phenotype of dendritic cell, monocyte, and lymphocyte deficiency is critical in identifying these patients, who present to a wide range of specialist services but rarely to hemato-oncology.¹²  Once identified, thorough hematologic evaluation is mandatory to exclude myeloid neoplasia, and annual bone marrow surveillance for clonal evolution is prudent. Finally, owing to the highly variable nature of GATA-2 associated syndromes, it is unlikely that a single approach to transplantation will be suitable for all patients.