Long-term outcome of fludarabine-based reduced-intensity allogeneic hematopoietic cell transplantation for debilitating paroxysmal nocturnal hemoglobinuria

Unmanipulated haploidentical donor and matched unrelated donor hematopoietic stem cell transplantation in patients with paroxysmal nocturnal hemoglobinuria: a single-center study

We analyzed the outcomes of 32 patients with paroxysmal nocturnal hemoglobinuria (PNH) who underwent either a haploidentical donor (HID) or a matched unrelated donor (MUD) hematopoietic stem cell transplantation (HSCT). Seventeen patients received an HSCT from an HID and 15 patients received an HSCT from an MUD. The median follow-up time of the surviving patients was 36 months (range: 12-96 months). No significant differences were observed in the 3-year overall survival (OS) between the HID and MUD cohorts (74.1%±11.4% vs. 93.3%±6.4%, respectively, p=.222) or in the 3-year failure-free survival (68.8%±11.8% vs. 86.7%±8.8%, respectively, p=.307). Treatment-related mortality occurred in five patients. A univariate analysis of risk factors revealed platelet engraftment failure negatively impacted OS and FFS. We conclude that HID and MUD-HSCT are feasible and can be effective options for those PNH patients with concomitant bone marrow failure, recurrent life-threatening thrombosis, and uncontrollable hemolysis.

Hematopoietic Stem Cell Transplantation for Patients with Paroxysmal Nocturnal Hemoglobinuria with or without Aplastic Anemia: A Multicenter Turkish Experience

Objective:

Although inhibition of the complement system at different steps is a promising therapy modality in patients with paroxysmal nocturnal hemoglobinuria (PNH), allogeneic hematopoietic stem cell transplantation (HCT) is still the only curative therapy, especially for patients with intractable hemolysis or bone marrow failure. The aim of this study is to evaluate the outcomes of allogeneic HCT in PNH patients with aplastic anemia (PNH-AA) or without.

Materials and Methods:

Thirty-five PNH/PNH-AA patients who were treated with allogeneic HCT in 10 transplantation centers in Turkey were retrospectively analyzed.

Results:

Sixteen (45.7%) and 19 (54.3%) patients were diagnosed with classical PNH and PNH-AA, respectively. The median age of the patients was 32 (18-51) years. The 2-year overall survival (OS) rate and rate of graft-versus-host disease-free, failure-free survival (GFFS) was 81.2% and 78.1%, respectively. The 2-year OS in cases of classical PNH and PNH-AA was 81.3% and 79.9%, respectively (p=0.87), and 2-year GFFS in cases of PNH and PNH-AA was 79% and 76% (p=0.977), without statistical significance. The OS and GFFS rates also did not differ between transplantations with matched sibling donors (MSDs) and matched unrelated donors (MUDs).

Conclusion:

Allogeneic HCT with MSDs or MUDs is a good option for selected patients with classical PNH and PNH-AA. In particular, patients with debilitating and refractory hemolysis and patients with bone marrow failure might form an excellent group of candidates for allogeneic HCT.

Advances in Hematopoietic Stem Cell Transplantation for Patients with Paroxysmal Nocturnal Hemoglobinuria

In the era of eculizumab, the number of patients with paroxysmal nocturnal hemoglobinuria (PNH) who undergo hematopoietic stem cell transplantation (HSCT) has decreased significantly. However, owing to the possibility of severe aplastic anemia (AA) or a suboptimal response to eculizumab, HSCT still plays an important role in the treatment of patients with PNH combined with AA or recurrent hemolysis-related symptoms despite its high level of risk. Here we review studies involving patients with PNH who underwent HSCT over the past 15 years and conclude that patients with refractory AA/PNH and patients with severe classical PNH are candidates for HSCT in countries where eculizumab is unavailable. The major causes of death from transplantation include graft-versus-host disease (GVHD), infection, and thrombotic microangiopathy. A haploidentical donor is a potential choice for patients without an HLA-matched donor. In addition, the use of eculizumab in combination with HSCT may help prevent GVHD.

Outcome of allogeneic hematopoietic stem cell transplantation in adult patients with paroxysmal nocturnal hemoglobinuria

The safety and efficacy of allogeneic hematopoietic stem cell transplantation (HSCT) for paroxysmal nocturnal hemoglobinuria (PNH) remain unclear. Therefore, we retrospectively analyzed the outcomes of 42 adult patients with PNH who underwent allogeneic HSCT using the registry database of the Japan Society for Hematopoietic Cell Transplantation. The median patient age was 32.5 years. The number of packed red cell (PRC) transfusions was < 20 times in 19 patients and ≥ 20 times in 16; 7 patients had missing data. Stem cell sources were bone marrow (N = 15) or peripheral blood (N = 13) from a related donor or bone marrow (N = 11) and cord blood (N = 3) from an unrelated donor. The cumulative incidence of neutrophil engraftment at day 40 was 81%. Six patients died before engraftment, and the 6-year overall survival (OS) was 74%. The OS of patients with < 20 pretransplant PRC transfusions was significantly higher than that of patients with ≥ 20 pretransplant PRC transfusions (95% vs. 63%; P < 0.05). Moreover, the OS of patients aged < 30 years was significantly higher than that of patients aged ≥ 30 years (90% vs. 59%; P < 0.05). Allogeneic HSCT for PNH could provide favorable survival; however, pretransplant transfusion burden and patient age should be considered when deciding the timing of allogeneic HSCT.

Allogeneic Hematopoietic Stem Cell Transplantation for Paroxysmal Nocturnal Hemoglobinuria: Multicenter Analysis by the Polish Adult Leukemia Group

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the sole potential cure for paroxysmal nocturnal hemoglobinuria (PNH); however, the data on its utility in PNH are limited. This retrospective analysis of patients with PNH who underwent allo-HSCT in 11 Polish centers between 2002 and 2016 comprised 78 patients with PHN, including 27 with classic PNH (cPNH) and 51 with bone marrow failure-associated PNH (BMF/PNH). The cohort was 59% male, with a median age of 29 years (range, 12 to 65 years). There was a history of thrombosis in 12% and a history of hemolysis in 81%, and 92% required erythrocyte transfusions before undergoing allo-HSCT. No patient received eculizumab, and 26% received immunosuppressive treatment. The median time from diagnosis to allo-HSCT was 12 months (range, 1 to 127 months). Almost all patients (94%) received reduced-toxicity conditioning, 66% with treosulfan. The stem cell source was peripheral blood in 72% and an identical sibling donor in 24%. Engraftment occurred in 96% of the patients. With a median follow-up of 5.1 years in patients with cPNH and 3.2 years in patients with BMF/PNH, 3-year overall survival (OS) was 88.9% in the former and 85.1% in the latter (P = not significant [NS]). The 3-year OS for patients with/without thrombosis was 50%/92% (P = NS) in the cPNH group and 83.3%/85.3% (P = NS) in the BMF/PNH group. The 3-year OS for in the BMF/PNH patients with/without hemolysis was 93.9%/62.9% (hazard ratio, .13; P = .016). No other factors impacted OS. After allo-HSCT, the frequency of the PNH clone was reduced to 0%, <1%, and <2.4% in 48%, 48%, and 4% of cPNH patients and in 84%, 11%, and 5% of BMF/PNH patients, respectively. The frequency of acute graft-versus-host disease (GVHD) grade II-IV was 23%, and the cumulative 1-year incidence of extensive chronic GVHD was 10.8% in the BMF/PNH group and 3.7% in the cPNH group. Allo-HSCT is a valid option for PNH patients, effectively eliminating the PNH clone with satisfactory overall survival and acceptable toxicity. Reduced-toxicity conditioning with treosulfan is effective and safe in patients with cPNH and BMF/PNH.

[Comparison of haploidentical hematopoietic stem cell transplantation and matched-sibling donor transplantation for the treatment of paroxysmal nocturnal hemoglobinuria]

Objective: To compare the outcomes between haploidentical donor hematopoietic stem cell transplantation (haplo-HSCT) and matched-sibling donor transplantation (MSD-HSCT) for paroxysmal nocturnal hemoglobinuria (PNH) . Methods: The clinical data of 40 PNH patients received HSCT (haplo-HSCT=25, MSD-HSCT=15) from July 2007 to May 2018 were analyzed retrospectively to compare the outcomes between haplo-HSCT and MSD-HSCT groups. Results: There were no differences in terms of gender, age, patients of PNH-AA and median time from diagnosis to transplantation between the 2 groups (P>0.05) . The median values of absolute mononuclear cell counts and CD34+ cells infused were 10.74 (4.80-22.86) ×108/kg and 12.19 (5.14-17.25) ×108/kg (P=0.866) , 3.57 (0.68-7.80) ×106/kg and 4.00 (3.02-8.42) ×106/kg (P=0.151) respectively, in haplo-HSCT and MSD-HSCT groups. All patients attained complete engraftment, no patient occurred graft failure. The median durations for myeloid and platelet engraftment were 12 (range, 9-26) and 11 (range, 7-15) days (P=0.065) , 19 (range, 11-75) and 13 (range, 11-25) days (P=0.027) respectively, in haplo-HSCT and MSD-HSCT groups. During a median follow-up of 26 (4-65) months in haplo-HSCT and 36 (4-132) months in MSD-HSCT groups (P=0.294) , the incidences of grade Ⅰ-Ⅳ acute graft-versus-host disease (aGVHD) were 32.0% and 20.0% (P=0.343) , grade Ⅱ-Ⅳ aGVHD were 16.0%, 13.3% (P=0.759) , chronic GVHD were 30.7% and 24.6% (P=0.418) , moderate-severe chronic GVHD were 12.7% and 7.1% (P=0.522) respectively, in haplo-HSCT and MSD-HSCT groups. The incidences of infection were 32.0% (8/25) and 26.7% (4/15) (P=1.000) respectively, in haplo-HSCT and MSD-HSCT groups. No patients occurred early death and relapse. Three-year estimated overall survival (OS) were (86.5±7.3) % and (93.3 ±6.4) % (P=0.520) , GVHD-free and failure-free survival (GFFS) were (78.3±8.6) % and (92.9±6.9) % (P=0.250) respectively, in haplo-HSCT and MSD-HSCT groups. Conclusion: The preliminary results indicated that haplo-HSCT was a feasible choice for PNH with favorable outcomes, haplo-HSCT and MSD-HSCT produced similar therapeutic efficacy.

Hematopoietic Cell Transplantation for Paroxysmal Nocturnal Hemoglobinuria in the Age of Eculizumab

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired clonal hematopoietic cell disease characterized by the destruction of hematopoietic cells through activation of the complement system with manifestations that can be life-threatening including hemolysis, thrombosis, and marrow failure. Allogeneic hematopoietic cell transplantation (HCT) remains the sole cure for PNH, but eculizumab, a terminal complement inhibitor of C5, has been used to prevent complement-mediated hemolysis in patients with PNH since its approval by the Food and Drug Administration in 2007. We examined outcomes of HCT in patients with PNH to evaluate the effects of disease subtype, conditioning intensity, and eculizumab use either pre-HCT or post-HCT. Fifty-five patients with a diagnosis of PNH underwent at least 1 HCT, with 4 patients requiring a second HCT for graft failure. The median age at the time of first HCT was 30.0 years (range, 4.2 to 66.9 years). Seventeen patients (30.9%) had classical PNH, and the remaining 38 patients had PNH associated with another marrow disorder (aplastic anemia in 26 of the 38). Indications for HCT included pancytopenia in 47.3% of the patients, myeloid malignancy (myelodysplastic syndrome, myeloproliferative neoplasm, or acute myelogenous leukemia) in 21.8%, recurrent hemolysis in 20.0%, and thrombosis in 10.9%. Of the 55 first HCTs, 26 were performed with myeloablative conditioning, 27 were performed with reduced-intensity conditioning, and 2 sets of identical twins underwent HCT without any conditioning. Donor types included HLA-matched related in 38.2%, HLA-matched unrelated in 34.5%, single HLA-allele mismatched unrelated in 16.4%, umbilical cord blood in 5.5%, syngeneic in 3.6%, and HLA-haploidentical in 1.8%. The median duration of follow-up in surviving patients was 6.1 years (range, 2.1 to 46.1 years) after first HCT. The median time to neutrophil and platelet engraftment was 17 days and 19 days, respectively; all but 2 patients (96.3%) had sustained engraftment. Overall survival was 70% at 5 years. Neither the choice of conditioning intensity nor PNH subtype affected survival. Nineteen patients died during follow-up, including 12 patients before day +365. Six patients received treatment with eculizumab before HCT, and 2 were treated after HCT. All patients treated with eculizumab were alive at a median follow-up of 2.3 years (range, .2 to 6.9 years). Both patients treated with eculizumab after HCT had minimal to no acute GVHD (aGVHD), with grade I skin aGVHD in 1 patient and no aGVHD in the other patient, and no chronic GVHD at 2.1 and 4.1 years post-HCT, respectively. With the approval of eculizumab, the indications for HCT include persistent hemolysis, persistent thrombosis, and associated marrow failure. Administration of eculizumab before and after HCT warrants further study, particularly considering our observation of minimal to no GVHD in 2 patients who received eculizumab after HCT.

How we treat paroxysmal nocturnal hemoglobinuria: A consensus statement of the Canadian PNH Network and review of the national registry

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by intravascular hemolysis, thrombophilia, and marrow failure. Its phenotype is due to absent or reduced expression of GPI-linked complement regulators and subsequent sensitivity of hematopoietic cells to complement-mediated damage and lysis. Introduction of the terminal complement inhibitor eculizumab drastically improved outcomes in PNH patients; however, despite this improvement, there remain several challenges faced by PNH patients and physicians who care for them. One of the most important is increasing awareness of the heterogeneity with which patients can present, which can lead to significant delays in recognition. Data from the Canadian PNH Registry are presented to demonstrate the variety of presenting symptoms. In Canada, geography precludes consolidation of care to just a few centers, so management is distributed across academic hospitals, linked together as the Canadian PNH Network. The Network over the last several years has developed educational programs and clinical checklists and has worked to standardize access to diagnostics across the country. Herein, we address some of the common diagnostic and therapeutic challenges faced by PNH physicians and give our recommendations. Gaps in knowledge are also addressed, and where appropriate, consensus opinion is provided.

Outcomes of allogeneic stem cell transplantation in patients with paroxysmal nocturnal hemoglobinuria with or without aplastic anemia

OBJECTIVE

The aim of this study was to evaluate the long-term outcomes of allogeneic stem cell transplantation (SCT) in patients with paroxysmal nocturnal hemoglobinuria (PNH) with or without aplastic anemia (AA).

METHOD

A total of 33 patients with PNH clones who underwent allogeneic SCT were analyzed.

RESULTS

After a median follow-up of 57 months (range, 6.0-151.3), the 5-year estimated overall survival rate was 87.9±5.7%. Four patients died of transplant-related mortality (TRM). With the exception of one patient with early TRM, 32 patients were engrafted. Two patients who had developed delayed GF received a second transplant and recovered. The cumulative incidences of acute graft-vs-host disease (GVHD) (≥grade II) and chronic GVHD (≥moderate) were 27.3±7.9% and 18.7±7.0%, respectively. Twenty-one patients receiving SCT with reduced-intensity conditioning (RIC) had available follow-up data for PNH cell population for the first 6 months post-transplant. Analysis of these data revealed that the PNH clones disappeared within approximately 2 months.

CONCLUSION

RIC regimen was sufficient to eradicate PNH clones with sustained donor-type engraftment after allogeneic SCT. Therefore, application of allogeneic SCT with RIC should be considered in patients with PNH, in accordance with the severity of the underlying bone marrow failure.

Allogeneic transplantation using CD34+ selected peripheral blood progenitor cells combined with non-mobilized donor T cells for refractory severe aplastic anaemia

Allogeneic haematopoietic stem cell transplantation is curative for severe aplastic anaemia (SAA) unresponsive to immunosuppressive therapy. To reduce chronic graft-versus-host disease (GVHD), which occurs more frequently after peripheral blood stem cell (PBSC) transplantation compared to bone-marrow transplantation (BMT), and to prevent graft rejection, we developed a novel partial T-cell depleted transplant that infuses high numbers of granulocyte colony-stimulating factor-mobilized CD34⁺ selected PBSCs combined with a BMT-equivalent dose of non-mobilized donor T-cells. Fifteen patients with refractory SAA received cyclophosphamide, anti-thymocyte globulin and fludarabine conditioning, and were transplanted with a median 8 × 10⁶ CD34⁺  cells/kg and 2 × 10⁷ non-mobilized CD3⁺ T-cells/kg from human leucocyte antigen-matched sibling donors. All achieved sustained engraftment with only two developing acute and two developing chronic GVHD. With a 3·5-year median follow-up, 86% of patients survived and were transfusion-independent. When compared to a retrospective cohort of 56 bone-marrow failure patients that received the identical transplant preparative regimen and GVHD prophylaxis with the exception that the allograft contained unmanipulated PBSCs, partial T-cell depleted transplant recipients had delayed donor T-cell chimerism and relative reduction of 75% in the incidence of acute grade II-IV GVHD (13% vs. 52%; P = 0·010) and of 82% in chronic GVHD (13% vs. 72%; P = 0·0004). In multivariate analysis, partial T-cell depleted transplants remained significantly associated with a reduced risk of GVHD. In conclusion, for patients with refractory SAA, this novel transplant strategy achieves excellent engraftment and survival when compared to unmanipulated PBSC transplants and dramatically reduces the incidence of both acute and chronic GVHD.

Generation of induced pluripotent stem cells as a potential source of hematopoietic stem cells for transplant in PNH patients

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia caused by lack of CD55 and CD59 on blood cell membrane leading to increased sensitivity of blood cells to complement. Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for PNH, however, lack of HLA-matched donors and post-transplant complications are major concerns. Induced pluripotent stem cells (iPSCs) derived from patients are an attractive source for generating autologous HSCs to avoid adverse effects resulting from allogeneic HSCT. The disease involves only HSCs and their progeny; therefore, other tissues are not affected by the mutation and may be used to produce disease-free autologous HSCs. This study aimed to derive PNH patient-specific iPSCs from human dermal fibroblasts (HDFs), characterize and differentiate to hematopoietic cells using a feeder-free protocol. Analysis of CD55 and CD59 expression was performed before and after reprogramming, and hematopoietic differentiation. Patients' dermal fibroblasts expressed CD55 and CD59 at normal levels and the normal expression remained after reprogramming. The iPSCs derived from PNH patients had typical pluripotent properties and differentiation capacities with normal karyotype. After hematopoietic differentiation, the differentiated cells expressed early hematopoietic markers (CD34 and CD43) with normal CD59 expression. The iPSCs derived from HDFs of PNH patients have normal levels of CD55 and CD59 expression and hold promise as a potential source of HSCs for autologous transplantation to cure PNH patients.

Distinct subgroups of paroxysmal nocturnal hemoglobinuria (PNH) with cytopenia: results from South Korean National PNH Registry

We retrospectively assessed the clinical characteristics of patients with paroxysmal nocturnal hemoglobinuria (PNH) according to severity of cytopenia. A total of 282 patients with hematological parameters assessed at the time of diagnosis of PNH were included. There were 24 patients with PNH/severe aplastic anemia (SAA) (at least two of the three criteria; hemoglobin ≤8 g/dL; absolute neutrophil count (ANC) <0.5 × 10(9)/L; platelet count <20 × 10(9)/L), 96 patients with PNH/aplastic anemia (AA) (at least two of the three criteria; hemoglobin ≤10 g/dL; ANC 0.5-1.5 × 10(9)/L; platelet count 20-100 × 10(9)/L), and 162 classic PNH patients. Compared with the classic PNH subgroup, the PNH/SAA subgroup had a significantly lower median granulocyte PNH clone size (26.7 vs. 51.0 %, P = 0.021) and lower incidence of lactate dehydrogenase ≥1.5 times the upper limit of normal (52.9 vs. 80.0 %, P = 0.049). The incidence of thromboembolism was similar in both subgroups. Overall survival was significantly lower in the PNH/SAA subgroup than in the classic PNH subgroup (P = 0.033). Our findings suggest that identification of patients with PNH/SAA at the time of diagnosis is important because of different clinical manifestations and poorer outcome compared with patients with classic PNH (clinicaltrials.gov identifier: #NCT01224483).