Outcomes of Antithymocyte Globulin-Post-Transplantation Cyclophosphamide-Cyclosporine-Based versus Antithymocyte Globulin-Based Prophylaxis for 10/10 HLA-Matched Unrelated Donor Allogeneic Hematopoietic Cell Transplantation

In 2015, dual T cell depletion with antithymocyte globulin (ATG) and post-transplantation cyclophosphamide (PTCy) combined with cyclosporine A (CsA) replaced our prior institutional graft-versus-host disease (GVHD) prophylaxis regimen of 4.5 mg/kg ATG, CsA, and mycophenolate mofetil (MMF) (ATG-based) in 10/10 HLA-matched unrelated donor (MUD) peripheral blood allogeneic hematopoietic stem cell transplantation (allo-HCT). The initial ATG dose of 4.5 mg/kg [ATG(4.5)/PTCy] was reduced to 2 mg/kg [ATG(2)/PTCy] in 2018. This study compares the results obtained from 444 adults undergoing MUD allo-HCT at our institution who received ATG(4.5)/PTCy (n = 127) or ATG(2)/PTCy (n = 223) with those who received ATG-based prophylaxis without PTCy (n = 84). The rates of grade II-IV and grade III-IV acute GVHD (aGVHD) at day +100 and moderate/severe chronic GVHD (cGVHD) at 1 year were 35.7%, 21.6%, and 14.7%, respectively, in patients receiving ATG-based prophylaxis without PTCy; 16.5%, 4.9%, and 4.3% in patients receiving ATG(4.5)/PTCy; and 23.3% (P = .004), 8.0% (P < .001), and 14.1% (P =.006) in patients receiving ATG(2)/PTCy. One-year overall survival (OS), nonrelapse mortality (NRM), and GVHD-free relapse-free survival (GRFS) were 69.8%, 25.3%, and 52.0%, respectively, for patients receiving ATG-based prophylaxis without PTCy; 82.7%, 17.3%, and 59.8% for patients receiving ATG(4.5)/PTCy; and 78.3% (P = .446), 14.7% (P = 101), and 56.2% (P = .448) for patients receiving ATG(2)/PTCy. On univariate analyses, the use of ATG(2)/PTCy was associated with a lower risk of NRM (hazard ratio, .54; P = .023) compared with the use of ATG-based prophylaxis without PTCy. ATG(2)/PTCy prophylaxis effectively prevents GVHD and is associated with comparable relapse risk, OS, and GRFS as seen with ATG(4.5)/PTCy and ATG-based prophylaxis without PTCy.

Late-onset Pneumocystis jirovecii pneumonia post-allogeneic stem cell transplantation after time-dependent discontinuation of prophylaxis

INTRODUCTION

Pneumocystis jirovecii pneumonia (PJP) is a rare complication of hematopoietic stem cell transplantation (HSCT). Primary prophylaxis for 6-12 months post-HSCT is the standard approach. However, there is no consensus regarding the optimal duration of prophylaxis.

METHODS

We identified patients who developed PJP more than 1-year post-HSCT. All patients had previously received 12 months of PJP prophylaxis. PJP was diagnosed based on clinical findings and the detection of P. jirovecii in bronchoalveolar lavage (BAL) using polymerase chain reaction (PCR). The CD4+ T-cell percentage was determined using flow cytometry. Data expressed as median (interquartile range).

RESULTS

Ten patients developed PJP at 17.5 months (16-24 months) post-HSCT. PJP diagnosis occurred 5.5 months (3-15 months) after discontinuing prophylaxis. Eight patients received anti-thymocyte globulin (ATG) as graft versus host disease (GVHD) prophylaxis. At diagnosis, only one patient had lymphopenia; all patients had CD4+ T-lymphocyte counts ≥0.2 × 109 /L (median 0.337 × 109 /L). Three patients had concomitant bacterial infections. The clinical presentation was mild; only three required hospitalization, none of them required intensive care and there were no deaths.

CONCLUSION

There is a need to develop risk-adapted prophylactic strategies in the contemporary era using ATG-based GVHD prophylaxis.

Acute Graft-versus-Host Disease: An Update on New Treatment Options

Acute graft-versus-host disease (GVHD) occurs in approximately 50% of patients and remains a primary driver of non-relapse and transplant-related mortality. The best treatment remains prevention with either in vivo or ex vivo T-cell depletion, with multiple strategies used worldwide based on factors such as institution preference, ability to perform graft manipulation, and ongoing clinical trials. Predicting patients at high risk for developing severe acute GVHD based on clinical and biomarker-based criteria allows for escalation or potential de-escalation of therapy. Modern therapies for treatment of the disease include JAK/STAT pathway inhibitors, which are standard of care in the second-line setting and are being investigated for upfront management of non-severe risk based on biomarkers. Salvage therapies beyond the second-line remain suboptimal. In this review, we will focus on the most clinically used GVHD prevention and treatment strategies, including the accumulating data on JAK inhibitors in both settings.

Post-transplant cyclophosphamide as sole GHVD prophylaxis after matched reduced-intensity conditioning allotransplant

BACKGROUND

Post-transplant cyclophosphamide (PTCY) alone as graft-versus-host disease (GVHD) prophylaxis may avoid/reduce short- and mid-term toxicities of drugs commonly used for GVHD prophylaxis, accelerate immune reconstitution after the graft to decrease infections and facilitate the early integration of adjunct maintenance therapies to prevent relapse.

OBJECTIVE

A prospective phase 2 study was designed in order to assess the feasibility and safety of PTCY as a sole GVHD prophylaxis in adult patients receiving a Baltimore-based reduced-intensity conditioning (RIC) peripheral blood (PB) allogeneic hematopoietic stem cell transplantation (Allo-HSCT) with a matched donor.

STUDY DESIGN

Patients were planned to be included stepwise up to 59 evaluable PTCY recipients, in order to be able to stop the protocol in case of excessive corticosteroid resistant grade 3-4 severe acute GVHD (aGVHD). Because a high incidence of grade 2-4 aGVHD was observed after analysis of the first 27 patients, the protocol was amended to test the addition of 1 day of anti-thymoglobulin to PTCY. In spite of this, the trial had to be stopped after 38 treated patients, because of an unacceptable rate of grade 3-4 aGVHD. Donors were matched related to 12 patients and unrelated to 26.

RESULTS

With a median follow-up of 29.6 months, 2-year overall, disease-free and GVHD-free relapse-free (GRFS) survivals were respectively 65.4%, 62.1% and 46.9%. Cumulative incidences of grade 2-4 and 3-4 aGVHD at day 100 were 52.6% and 21.1%, respectively, while that of moderate/severe chronic(c) GVHD was 15.7% at 2 years. Addition of ATG to PTCY did influence neither aGVHD, cGVHD nor GRFS.

CONCLUSION

Despite paradoxically good survivals, especially GRFS, this study failed to demonstrate that PTCY (± ATG) alone can be used for Baltimore-based RIC PB Allo-HSCT with matched donors. Other combinations should be tested to try and avoid long-term use of immunosuppressive drugs following Allo-HSCT in this setting.

Should anti-thymocyte globulin be added in post-transplant cyclophosphamide based matched unrelated donor peripheral blood stem cell transplantation for acute myeloid leukemia? A study on behalf of the Acute Leukemia Working Party of the EBMT

In this registry-based study which includes acute myeloid leukemia patients who underwent a matched unrelated donor allogeneic peripheral-blood stem cell transplantation in complete remission and received post-transplant cyclophosphamide (PTCY) as graft-versus-host disease (GvHD) prophylaxis, we compared 421 recipients without anti-thymocyte globulin (ATG) with 151 patients with ATG. The only significant differences between PTCY and PTCY + ATG cohorts were the median year of transplant and the follow-up period (2017 vs 2015 and 19.6 vs 31.1 months, respectively, p < 0.0001). Overall, 2-year survival was 69.9% vs 67.1% in PTCY and PTCY + ATG, respectively, with deaths related to relapse (39% vs 43.5%), infection (21.9% vs 23.9%) or GvHD (17.1% vs 17.4%) not differing between groups. On univariate comparison, a significantly lower rate of extensive chronic GvHD was found when ATG was added (9.9% vs 21%, p = 0.029), a finding which was not confirmed in the multivariate analysis. The Cox-model showed no difference between PTCY + ATG and PTCY alone with respect to acute and chronic GvHD of all grades, non-relapse mortality, relapse, leukemia-free survival, overall survival, and GvHD-free-relapse-free survival between study cohorts. Our results highlight that the addition of ATG in PTCY does not provide any extra benefit in terms of further GvHD reduction, better GRFS or better survival.

Low-dose post-transplant cyclophosphamide with low-dose antithymocyte globulin for prevention of graft-versus-host disease in first complete remission undergoing 10/10 HLA-matched unrelated donor peripheral blood stem cell transplants: a multicentre, randomized controlled trial

The most widely used regimens of graft-versus-host disease (GVHD) prophylaxis in HLA-matched unrelated donor peripheral blood stem cell transplantation (MUD-PBSCT) are based on anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). To improve the efficiency of GVHD prophylaxis, a novel regimen, composed of low-dose PTCy (20 mg/kg on day +3 and +4) and low-dose ATG (6 mg/kg), was evaluted in patients with hematological malignancies ungoing 10/10 HLA MUD-PBSCT in first remission (CR1). In our prospective, multicenter study, 104 patients were randomly assigned one-to-one to low-dose PTCy-ATG (n = 53) or standard-dose ATG (10 mg/kg, n = 51). Both the cumulative incidences (CIs) of grade II-IV acute GVHD (aGVHD) and chronic GVHD (cGVHD) at 2 years in low-dose PTCy-ATG cohort were significantly reduced (24.5% vs. 47.1%; P = 0.017; 14.1% vs. 33.3%; P = 0.013). The CI of non-relapse-mortality (NRM) was much lower (13.2% vs. 34.5%; P = 0.049) and GVHD-free, relapse-free survival (GRFS) was significantly improved at 2 years in low-dose PTCy-ATG arm (67.3% vs 42.3%; P = 0.032). The low-dose PTCy-ATG based GVHD prophylaxis is a promising strategy for patients in CR1 after 10/10 HLA MUD-PBSCT.

Addition of a Single Low Dose of Anti T-Lymphocyte Globulin to Post-Transplant Cyclophosphamide after Allogeneic Hematopoietic Stem Cell Transplant: A Pilot Study

Correlation between risk of graft-versus-host disease (GvHD) and CD3⁺ counts within the peripheral blood stem cell graft has recently been reported in the setting of post-transplant cyclophosphamide (PT-Cy). We aimed to investigate the benefit of the addition of a single dose of anti-T lymphocyte globulin (ATLG 5 mg/kg) to PT-Cy in this setting. Starting in 2019, all patients receiving PBSC transplant containing CD3⁺ counts above 300 × 10⁶/kg (study group) received a post-transplant dose of ATLG in addition to standard PT-Cy. The study was designed as a real-life analysis and included all consecutive Hematopoietic Stem Cell Transplantation (HSCT) recipients according to the above-mentioned inclusion criterion (n = 21), excluding cord blood and bone marrow donors. Using a 1:2 matched-pair analysis, we compared the outcomes with a historical population who received PT-Cy only (control group). We found a delayed platelet engraftment (29% vs. 45% at 30 days, p = 0.03) and a non-significant trend toward higher risk of poor graft function (29% vs. 19%, p = 0.52). The addition of ATLG impacted long-term immune reconstitution on the CD4⁺ subsets, but this did not translate into higher rate of relapse or viral infection. Acute GvHD was not significantly impacted, but 1-year cumulative incidence of chronic GvHD was significantly lower in the study group (15% vs. 41%, p = 0.04). Survival outcomes were comparable. In conclusion PT-Cy and ATLG was overall safe and translated into a low rate of chronic GvHD incidence.

Anti-thymocyte Globulin and Post-Transplant Cyclophosphamide do not abrogate the inferior outcome risk conferred by human leukocyte antigen-A and -B mismatched donors

In donor selection for allogeneic stem cell transplant, several factors are considered for potential impact on transplant outcome. Previous publications suggested single HLA-mismatched unrelated donors (MMUD) may be equivalent to 10/10 matched unrelated donors (MUDs). We retrospectively examined factors affecting outcome in a single-center study using ATG followed by post-transplant cyclophosphamide, termed ATG-PTCy, GvHD prophylaxis. Fifty-two patients who received grafts from MMUD and 188 patients transplanted from MUD between January 2015 and December 2019, at Princess Margaret Cancer Centre, Canada, were enrolled. All patients received reduced-intensity conditioning. Overall survival for 9/10 recipients at 2 years was significantly worse, 37.2% versus 68.5% for 10/10 MUDs, p < .001, as were NRM at 1 year 39.5% versus 11.7%, p < .001, and GRFS at 2 years 29.8% versus 58.8%, p < .001, respectively, potentially due to higher incidence of infections including CMV. By multivariable analysis, factors correlating with survival negatively were DRI, and MMUD, whereas for NRM MMUD and increasing age were unfavorable. For GRFS significant unfavorable factors included donor age ≤32 years, female donor to male recipient, DRI high-very high and MMUD. These data suggest that MMUD, primarily HLA-A and HLA-B MMUD, confer significantly inferior outcome despite use of ATG-PTCy. Further development of novel conditioning regimens and GvHD prophylaxis is needed to mitigate these risks.

Successful mismatched hematopoietic stem cell transplantation for pediatric hemoglobinopathy by using ATG and post-transplant cyclophosphamide

The use of HLA-mismatched (un)related donors is historically associated with a higher incidence of transplant-related complications and mortality. However, the use of such donors may overcome the limited availability of HLA-matched donors for patients with β-thalassemia major (TM) and sickle cell disease (SCD). We investigated hematopoietic stem cell transplantation (HSCT) outcomes of pediatric TM and SCD patients treated with a mismatched donor using a treosulfan-based conditioning in combination with ATG and post-transplant cyclophosphamide (PT-CY) and compared these results to the clinical outcome of patients treated by matched donor HSCT without PT-CY. Thirty-eight children (n = 24 HLA-identical or 10/10-matched donors; n = 14 HLA-mismatched donors), who received a non-depleted bone marrow graft were included. Event-free survival (EFS) and GvHD were not higher in the mismatched PT-Cy group as compared to the matched group. Moreover, despite delayed neutrophil engraftment (day +22 vs. +26, p = 0.002) and immune recovery in the mismatched PT-Cy group, this did not result in more infectious complications. Therefore, we conclude that in the absence of an HLA-identical or a matched unrelated donor, HSCT with a mismatched unrelated or haploidentical donor in combination with ATG plus PT-CY can be considered a safe and effective treatment option for pediatric hemoglobinopathy patients.

Efficiency and Toxicity of Ruxolitinib as a Salvage Treatment for Steroid-Refractory Chronic Graft-Versus-Host Disease

Graft-versus-host disease (GVHD), especially steroid-refractory GVHD, remains a life-threatening complication after hematopoietic stem cell transplantation (HSCT). The effect of the JAK1/2 kinase inhibitor ruxolitinib on treating steroid-refractory acute GVHD has been verified by the REACH1/2 study; however, its safety and efficacy in patients with steroid-refractory chronic GVHD (SR-cGVHD) remain unclear. In this retrospective study, 70 patients received ruxolitinib as a salvage therapy for SR-cGVHD. Twenty-four weeks after ruxolitinib treatment, the overall response rate (ORR) was 74.3% (52/70), including 34 patients who achieved complete remission (CR) and 18 who achieved partial remission (PR). The main adverse event was cytopenia, which occurred in 51.4% (36/70) of patients. After ruxolitinib treatment, the percentage of CD4 cells increased from 18.20% to 23.22% (P<0.001), while the percentages of NK (CD16⁺CD56⁺) cells and regulatory T cells (CD4⁺CD127 ^± CD25⁺) decreased (P<0.001, P<0.001). Among the B cell subsets, the proportion of total B cells approximately tripled from 3.69% to 11.16% (P<0.001). Moreover, we observed a significant increase in IL-10 levels after ruxolitinib treatment (P=0.025) and a remarkable decrease in levels of suppression of tumorigenicity 2 (ST2) from 229.90 ng/ml to 72.65 ng/ml. The median follow-up after the initiation of ruxolitinib treatment was 401 (6-1076) days. The estimated one-year overall survival rate of the whole group was 66.0% (54.4-77.6%, 95% CI), and the one-year overall survival rate of patients with mild and moderate cGVHD was 69.6% (57.4-81.8%, 95% CI), which was better than that of patients with severe cGVHD (31.3%, 0.0-66.2%, 95% CI) (P=0.002). Patients who achieved a CR and PR achieved better survival outcomes (84.5%, 73.9-95.1%, 95% CI) than those who showed NR to ruxolitinib treatments (16.7%, 0-34.3%, 95% CI) (P<0.001). At the final follow-up, cGVHD relapse occurred in six patients after they reduced or continued their ruxolitinib doses. Collectively, our results suggest that ruxolitinib is potentially a safe and effective treatment for SR-cGVHD.

Infusion of Mesenchymal Stem Cells to Treat Graft Versus Host Disease: the Role of HLA-G and the Impact of its Polymorphisms

Hematopoietic stem-cell transplantation is widely performed for the treatment of hematologic diseases and is increasingly being used for the experimental treatment of various autoimmune diseases. Despite the rapid evolution of this therapy, the mortality rate of patients undergoing this procedure is still high, mainly due to the development of graft versus host disease (GvHD). Even with the administration of immunosuppressive therapy, some patients manifest the chronic form of the disease. For these cases, infusion of mesenchymal stem cells (MSCs) was proposed as a therapeutic strategy, considering the immunosuppressive potential of these cells. This review describes the main results obtained in cell therapy with MSCs for the treatment of GvHD. Despite the encouraging results found, some points differed among the studies. Although the factors that influence the different results are uncertain, some investigators have suggested that variations in immunosuppressive molecules are responsible for these divergences. We highlight the key role of the HLA-G gene in modulating the immune response, and the importance of the polymorphisms and alleles of this gene associated with the outcome of the transplants. We suggest that the HLA-G gene and its polymorphisms be analyzed as a factor in selecting the MSCs to be used in treating GvHD, given its strong immunosuppressive role.

Patterns of infection and infectious-related mortality in patients receiving post-transplant high dose cyclophosphamide as graft-versus-host-disease prophylaxis: impact of HLA donor matching

Post-transplant cyclophosphamide (PTCy) has become a promising option after allo-SCT, but infections may be more common than in traditional protocols. We herein report 117 consecutive adults who received PTCy-based alloSCT in our hospital: HaploSCT (34%), MRD (19%), and VUD (47%), respectively. The 18-month incidence of severe bacterial, viral, and IFI was 56%, 69%, and 8.7%, without differences between donor type, except for CMV infection and viral hemorrhagic cystitis, which had a higher incidence in the haploSCT cohort (58% vs. 43% and 30% vs. 8% on day +90, p < 0.05). Late infections by conventional respiratory viruses were common in all groups [33/87 (38%)]. The 2-year survival was 72% and did not differ by donor type. IRM at day 30, day 100, and 18 months was 1.7%, 4.4%, and 12%, without differences by donor type (p = 0.7). The primary cause of IRM was bacterial infection (42%). Grade 2–4 acute GvHD was the only independent predictor of IRM. Donor type had no impact on IRM or on survival. In our study, severe infections were common in all donor types using PTCy, with higher rates of early post-engraftment CMV-I and viral HC in haploSCT recipients, although lethal infections were uncommon and similar in all donor types.

The outcome of two or more HLA loci mismatched unrelated donor hematopoietic cell transplantation for acute leukemia: an ALWP of the EBMT study

A mismatched unrelated (MMUD) donor represents an alternative therapeutic option for patients who need allogeneic hematopoietic cell transplantation (allo-HCT) and do not have a human leukocyte antigen (HLA) matched donor. We studied outcomes of patients with acute leukemia transplanted from ≥2 HLA allele MMUD. The study population consisted of 465 patients. The median follow-up period was 63 and 75 months in the AML and ALL groups, respectively. The incidence of grade II-IV and grade III-IV acute (a) graft-versus-host disease (GVHD) during the first 100 days was 37% and 16%, respectively. Total and extensive chronic (c) GVHD rates at 2 years were 38% and 17%, respectively. In the entire population, the 5-year relapse incidence (RI), non-relapse mortality (NRM), leukemia-free survival (LFS), overall survival and refined GVHD-free, relapse-free survival (GRFS) was 33%, 31%, 37%, 41%, and 27%, respectively. In the multivariate analysis, HLA-DR mismatch was a poor prognostic factor, giving a significantly higher NRM [hazard ratio (HR), 1.67, p = 0.02]; poorer LFS (HR, 1.42, p = 0.03); OS (HR, 1.46, p = 0.03) and higher aGVHD grade II-IV (HR, 1.46, p = 0.05). In this study, allo-HCT from ≤6/8 HLA allele MMUD in acute leukemia patients resulted in acceptable LFS and refined GRFS. HLA-DR mismatch was a poor prognostic factor.

Post-Transplant Cyclophosphamide Combined with Anti-Thymocyte Globulin as Graft-versus-Host Disease Prophylaxis for Allogeneic Hematopoietic Cell Transplantation in High-Risk Acute Myeloid Leukemia and Myelodysplastic Syndrome

BACKGROUND

Allogeneic hematopoietic cell transplantation (HCT) is curative for high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) but with significant non-relapse mortality (NRM) and relapse. We compared the combination of anti-thymocyte globulin (ATG; 4.5 mg/kg) and post-transplant cyclophosphamide (PTCy; 50 mg/kg on day +3 and +4) with other graft-versus-host disease (GvHD) prophylaxis regimens used for these patients.

METHODS

We retrospectively analyzed 159 patients, aged 22-73 (median 56) years, having undergone transplantation for high-risk AML (n = 120) or MDS (n = 39). The donors were matched related (33%), unrelated (55%) and haploidentical (12%). Almost all patients used peripheral blood stem cells. Conditioning was myeloablative (34%) or reduced intensity (66%). ATG + PTCy was used in 69 patients (43%), and other GvHD prophylaxis regimens in 90 patients (57%).

RESULTS

Grade III-IV acute GvHD occurred in 4% of the ATG + PTCy patients versus 20% of those using other regimens (p = 0.004), and chronic GvHD in 19% of the ATG + PTCy patients versus 41% of those using other regimens (p = 0.003). Two-year GvHD-free relapse-free survival (GRFS) was 30% with ATG + PTCy versus 18% with other regimens (p = 0.04). Multivariable analysis demonstrated that while ATG + PTCy had no significant influence on overall survival, cumulative incidence of relapse or NRM, there was a significant influence on GRFS in favor of ATG + PTCy (HR = 0.69, 95% CI 0.45-0.99, p = 0.04).

CONCLUSIONS

We conclude that the ATG + PTCy combination significantly improved GRFS in allogeneic HCT for high-risk AML and MDS without influencing other outcomes.

Incorporating posttransplant cyclophosphamide-based prophylaxis as standard-of-care outside the haploidentical setting: challenges and review of the literature

Posttransplant high-dose cyclophosphamide (PTCy) effectively prevents GvHD after haploidentical SCT. However, its use in HLA-matched SCT has been less explored. Fifty-six consecutive patients who underwent allo-SCT for hematological malignancies have been included in this prospective single-center protocol. Donors have been HLA-identical siblings, fully-matched unrelated or 1-allele-mismatched unrelated donors in 30%, 32%, and 37% of cases, respectively. Nine patients have received a TBI-containing MAC regimen, while the remaining (84%) received RIC platforms based on Fludarabine plus Busulfan/Melphalan. Due to the high graft failure (GF) rate (21%) in a preliminary analysis in the allo-RIC cohort (n = 29), protocol amendments have been implemented, with no further cases of GF after the introduction of mini-thiotepa (0/18). The overall incidence of grade II-IV acute GvHD is 24% (95% CI: 17-31%) with four steroid-refractory cases. Severe chronic GvHD has occurred in only 1 of 43 evaluable cases. The 1-year NRM and relapse are 18% (95% CI: 12-26%) and 30% (18-42%) and the OS and DFS are 78% and 64%, respectively. These outcomes support the feasibility of using PTCy as a SOC outside the haplo-setting, albeit mini-thiotepa (3 mg/kg) was incorporated in the standard allo-RIC platforms to prevent GF. Despite the limitations of a single-center experience and the short follow-up, these protocols show promising results with particular benefit in reducing the occurrence of moderate-to-severe GvHD.

Reduced-intensity conditioning allogeneic transplant with dual T-cell depletion in myelofibrosis

BACKGROUND

There remains a significant mortality in recipients with MF who undergo allogeneic stem cell transplant (allo-HSCT). The combination of antithymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) provides good control of graft-versus-host disease (GVHD) when peripheral blood stem cell grafts are used.

METHODS

We report the outcome of 37 recipients with myelofibrosis who underwent reduced-intensity conditioning (RIC) allo-HSCT with ATG and PTCy. Median follow-up was 16.4 months.

RESULTS

Nine (24.3%) recipients received 10/10 MRD grafts, 17 (45.9%) 10/10 MUD grafts, 4 (10.8%) 9/10 MUD grafts, and 7 (18.9%) haploidentical donor grafts. Six (16.3%) patients had graft failure. The cumulative incidence of grade II-IV and grade III-IV aGVHD at day +100 and moderate/severe chronic GVHD at 1 year was as follows: 13.5%, 5.4%, and 17%. There were no deaths secondary to GVHD. One-year overall survival (OS), relapse-free survival (RFS), non-relapse mortality (NRM), and GVHD-free/RFS (GRFS) were respectively 74.4%, 71.3%, 23%, and 43.3%. Those recipients who had worse KPS ≤ 80% had worse OS and RFS.

CONCLUSION

RIC allo-HSCT with ATG and PTCy results in high OS and RFS in patients with myelofibrosis and absence of mortality secondary to GVHD. Further investigations are required to reduce NRM and graft failure rates.

Reduced intensity allogeneic stem cell transplant with anti-thymocyte globulin and post-transplant cyclophosphamide in acute myeloid leukemia

OBJECTIVES

We aimed to study the efficacy of reduced intensity conditioning (RIC) allo-HSCT combined with anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis in AML.

METHODS

One hundred forty-seven patients were included. All patients underwent unmanipulated peripheral blood stem cell RIC allo-HSCT. Median follow-up was 12.8 months (range 0.5-39).

RESULTS

Median age was 58 years. Twenty-nine (20%) recipients received 10/10 MRD grafts, 69 (47%) 10/10 MUD grafts, 20 (13.6%) 9/10 MMUD, and 29 (20%) haploidentical grafts. The cumulative incidence of grade II-IV and III-IV acute GVHD at day +100, and moderate/severe chronic GVHD at 1-year were as follow: 14.3%, 1.4%, and 8.3%. There were no significant differences according to donor type (P = .46) and cumulative incidence of GVHD. One-year overall survival (OS), relapse-free survival (RFS), non-relapse mortality, and GVHD-free/Relapse-free survival were as follows: 66.9% (95% CI 58.4-74), 59.9%, and 18.7% and 53.7%. KPS ≤ 80 was predictive of worst OS (P = .04). Those recipients who received MUD transplants had better RFS (P = .01).

CONCLUSIONS

RIC allo-HSCT combined with ATG and PTCy is safe and a potentially curative strategy and it is associated with impressive GRFS in AML.

Low-dose post-transplant cyclophosphamide and anti-thymocyte globulin as an effective strategy for GVHD prevention in haploidentical patients

BACKGROUND

Low-dose post-transplant cyclophosphamide (PTCy) in conjunction with anti-thymocyte globulin (ATG) appears as a potentially effective graft-versus-host disease (GVHD) prevention strategy in haploidentical hematopoietic cell transplant (haplo-HCT). Our study aims to assess the efficacy of this regimen.

METHODS

We extended our prospective study in patients treated with low-dose PTCy (14.5 mg/kg on days 3 and 4) in ATG/granulocyte colony-stimulating factor (G-CSF)-based regimen and compared the results to the contemporary cohort of patients without low-dose PTCy (ATG cohort). Both study cohort and control are transplanted from maternal donor or collateral relatives.

RESULTS

We identified 239 consecutive patients (ATG-PTCy cohort = 114; ATG cohort = 125). All patients but one in ATG cohort achieved myeloid engraftment by day 30 post-HCT. We found that both the cumulative incidence of 100-day grade III-IV aGvHD and non-relapse-mortality (NRM) in the ATG-PTCy cohort was significantly reduced than that in the ATG group (5% vs 18%; P = 0.003; and 6% vs 15%; P= 0.045); the 2-year cumulative incidences of relapse and overall survival were comparable between the two cohorts (13% vs 14%; P = 0.62; and 83% vs 77%; P = 0.18, respectively). Furthermore, GVHD-free, relapse-free survival (GRFS) was significantly improved in the ATG-PTCy arm (63% vs 48%; P = 0.039). In multivariate analysis, the joint treatment resulted in lower grade II-IV acute GVHD (HR 0.58; P = 0.036), grade III-IV aGvHD (HR 0.28; P = 0.006), chronic GVHD (HR 0.60; P = 0.047), NRM (HR 0.26; P = 0.014), and higher GRFS (HR 0.59; P = 0.021) but slower myeloid and platelet recovery (HR 0.29 and 0.30; both P < 0.001).

CONCLUSIONS

These results suggested that ATG/PTCy (low-dose) can reduce both acute and chronic GVHD as compared with standard ATG-based prophylaxis using maternal donor or collateral relatives at particular high GVHD risk.