Optimal Active Anti-Thymocyte Globulin Exposure Associated with Minimum Risk of Virus Reactivation and Comparable Acute Graft-Versus-Host Disease Under Adult Myeloablative Haploidentical Peripheral Blood Stem Cell Transplantation

Female-to-male allogeneic transplantation affects outcomes differently according to the type of haplo-transplantation

Allogeneic hematopoietic stem cell transplantation from a female donor to a male recipient (female-to-male allo-HCT) is a well-established risk factor for chronic graft-versus-host disease (GVHD) and non-relapse mortality (NRM). The inferior outcomes of female-to-male allo-HCT are considered to be due to allo-immunity against H-Y antigens. However, the influence of minor histocompatibility antigens in haplo-identical allo-HCT remains to be elucidated. We investigated the impact of female-to-male allo-HCT according to the haplo-HCT subtype. In the post-transplant cyclophosphamide (PTCY) cohort (n = 660), a female-to-male sex-mismatch was significantly associated with a decreased risk of relapse (HR: 0.70 [95% CI: 0.49-0.99], P = 0.045), but not with overall survival (OS) or NRM (HR: OS 0.89 [95% CI: 0.68-1.16], P = 0.40; NRM 0.98 [95% CI: 0.68-1.41], P = 0.90). On the other hand, in the non-PTCY cohort (n = 219), a female-to-male sex-mismatch was associated with inferior risks of OS and NRM, but was not associated with relapse. These results suggested that the survival impact of the haplo-HCT subtype differed according to the presence of a sex-mismatch. PTCY might be feasible for overcoming the inferiority of female-to-male allo-HCT and might preserve a GVL effect against H-Y antigens.

Patients Beyond the Optimal Range of rATG-AUC Still Benefit from the Targeted Dosing Strategy in Unmanipulated Haplo-PBSCT

Rabbit antithymocyte globulin (rATG) is widely used in allogeneic hematopoietic stem cell transplantation to prevent graft failure and severe graft-versus-host disease (GVHD). We developed a rATG-targeted dosing strategy based on the optimal areas under the concentration-time curve (AUC) of active rATG. This study compared the outcomes of the optimal AUC arm with nonoptimal AUC arm to assess the effect of the rATG-targeted dosing strategy. Eighty patients (median age: 32 years) with hematological malignancies who received their first haplo-PBSCT were enrolled successively. With rATG-targeted dosing, the AUC values of 60 patients (75%, optimal AUC arm) fell within the optimal range (100-148.5 UE/mL/day) and 20 fell beyond this range (nonoptimal AUC arm). In the historical control group of 102 haplo-PBSCT patients who received a fixed dose of rATG (10 mg/kg), less patients fell within the optimal range (57.8%, P = .016). Looking at the nonoptimal AUC arms in both groups, lower cumulative incidence of CMV was noted in the targeted dosing group compared with the historical control group(50.0%, 95% CI, 30.8%-72.9% versus 81.4%, 95% CI, 68.6%-91.3%; P = .004). The cumulative incidences of EBV, relapse, overall survival and disease-free survival tended to be superior in the nonoptimal AUC arm in the targeted dosing group compared with the historical control. In the targeted dosing group, the cumulative incidence of cytomegalovirus (CMV) reactivation on day +180 tended to be lower in the optimal AUC arm (30.0%, 95% CI, 20.1%-43.3%) compared with the nonoptimal AUC arm (50.0%, 95% CI, 30.8%-72.9%, P = .199) without statistical difference. There were no significant differences of acute or chronic GVHD, relapse, nonrelapse mortality, overall survival, disease-free survival or lymphocyte reconstitution between the two arms. In conclusion, the rATG-targeted dosing strategy made the exposure of active rATG in more patients with the optimal AUC range. Even patients who fell beyond this range would still benefit from the strategy.

Real-World Impact of Routine Addition of Antithymocyte Globulin to Standard GVHD Prophylaxis in Myeloablative Unrelated Donor Transplants: Important Gains in Graft-versus-Host Disease Prevention though No Difference in Overall Survival

INTRODUCTION

Antithymocyte globulin (ATG) has been demonstrated to reduce the incidence of graft-versus-host disease (GVHD); however, it remains controversial whether these gains are offset by an increase in relapse.

METHODS

We conducted a retrospective historical control study consisting of patients (n = 210) who underwent myeloablative allogeneic hematopoietic stem-cell transplantation (HSCT) from 2014 to 2020.

RESULTS

The incidence of acute GVHD was lower in the ATG group (51.4%) than the non-ATG group (control) (70.0%, p = 0.010). The incidence of chronic GVHD was also lower in the ATG group at 1-year (36.4% vs. 62.9%, p < 0.001) and 2-year (40.0% vs. 65.7%, p < 0.001) post-HSCT. The mortality due to GVHD was higher in the control (18.5%) than the ATG group (4.3%; p = 0.024). The severe GVHD-relapse-free survival was higher in the ATG group (36.4%) than the control (12.9%; p < 0.001). Nevertheless, the 2-year overall survival was similar.

CONCLUSION

Our results confirm the effectiveness of ATG in prevention of GVHD in the real-world setting and enhanced GVHD-free survival. An important result is the equalization of overall survival between the ATG and control groups at 1- and 2-year post-HSCT and implies that earlier GVHD-associated mortality may be offset by later relapse mortality producing similar overall survival over time.

[Chinese expert consensus on the diagnosis and treatment of chronic graft-versus-host disease (2024)]

Chronic graft-versus-host disease (cGVHD) is a common and severe complication following allogeneic hematopoietic stem cell transplantation, which significantly impacts patients' survival and quality of life. In recent years, notable progress has been made in the diagnosis, prevention, and treatment of cGVHD, driven by the emergence of novel therapies such as targeted drugs and the advancement of clinical research. This consensus, based on the latest developments in cGVHD research and growing data from evidence-based medicine, has been revised and updated from the "Chinese consensus on the diagnosis and management of chronic graft-versus-host disease (2021)" to better guide clinical practice.

Targeted dosing of anti-thymocyte globulin in adult unmanipulated haploidentical peripheral blood stem cell transplantation: A single-arm, phase 2 trial

Anti-thymocyte globulin (ATG) is widely used in allogeneic hematopoietic stem cell transplantation to prevent severe graft-versus-host disease (GVHD) and graft failure. However, overexposure to ATG may increase cytomegalovirus (CMV), Epstein-Barr virus (EBV) reactivation, non-relapse mortality, and disease recurrence. To investigate the optimal dosing of ATG, we established a targeted dosing strategy based on ATG concentration monitoring for haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). The aim of this phase 2 trial is to evaluate the safety and efficacy of the ATG-targeted dosing strategy in adult unmanipulated haplo-PBSCT. ATG was administered for 4 days (-5 days to -2 days) during conditioning. The ATG doses on -3 days and -2 days were adjusted by our dosing strategy to achieve the optimal ATG exposure. The primary endpoint was CMV reactivation on +180 days. Between December 2020 and January 2022, 66 haplo-PBSCT patients were enrolled and 63 of them were evaluable with a median follow-up of 632 days. The cumulative incidence of CMV reactivation was 36.7% and that of EBV was 58.7%. The 1-year disease-free survival was 82.5%, overall survival was 92.1%, and CD4+ T-cell reconstruction on +100 days was 76.8%. The most common severe regimen-associated toxicities (> grade 3) were infections (51.5%) and gastrointestinal toxicity (25.5%). A total of 102 haplo-PBSCT patients who received the conventional fixed ATG dose (cumulative 10 mg/kg) comprised historical control. The outcomes in historical control were inferior to those of phase 2 trial cohort (CMV reactivation: 70.8%, p < .001; EBV reactivation: 76.0%, p = .024; CD4 + T-cell reconstruction: 54.1%, p = .040). In conclusion, ATG-targeted dosing strategy reduced CMV/EBV reactivation and improved survival without increasing GVHD after haplo-PBSCT. These advantages may be associated with accelerated immune reconstitution.

Features of cytomegalovirus infection and evaluation of cytomegalovirus-specific T cells therapy in children’s patients following allogeneic hematopoietic stem cell transplantation: A retrospective single-center study

Cytomegalovirus (CMV) infection remains a critical cause of mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT), despite improvement by pre-emptive antivirus treatment. CMV-specific cytotoxic T lymphocytes (CMV-CTL) are universally used and proven well-tolerance after allo-HSCT in adult clinical trials. However, it is not comprehensively evaluated in children’s patients. Herein, we conducted a retrospective study to determine the risk factors of CMV infection and evaluation of CMV-CTL in children patients who underwent allo-HSCT. As result, a significantly poor 5-year overall survival was found in the CMV infection group (87.3 vs. 94.6%, p=0.01). Haploidentical HSCT (haplo-HSCT) was identified as an independent risk factor for CMV infection through both univariate and multivariate analyses (p<0.001, p=0.027, respectively). Furthermore, the cumulative incidence of CMV infection was statistically higher in the haplo-HSCT group compared to the HLA-matched donor group (44.2% vs. 21.6%, p<0.001). Finally, the overall response rate of CMV-CTL was 89.7% (26/29 patients) in CMV infection after allo-HSCT. We concluded that CMV infection following allo-HSCT correlated with increased mortality in children’s patients, and haplo-HSCT was an independent risk factor for CMV infection. Adoptive CMV-CTL cell therapy was safe and effective in pediatric patients with CMV infection.