Adoptive transfer of CMV-specific TCR-T cells for the treatment of CMV infection after haploidentical hematopoietic stem cell transplantation.

BACKGROUND: Cytomegalovirus (CMV) reactivation after unmanipulated haploidentical stem cell transplantation (SCT) frequently occurs, causing life-threatening morbidities and transplantation failure. Pre-emptive therapy upon the detection of CMV viremia using antiviral agents is currently the standard of care but it was associated with significant toxicity. The CMV antigen-specific cytotoxic T lymphocyte therapy was limited by the time-consuming manufacture process and relatively low success rate. More effective and safer approaches for the treatment of CMV reactivation after haploidentical SCT are in urgent need. METHODS: A single-arm, open-label, phase I clinical trial evaluating the safety and efficacy of CMV-targeting T cell receptor-engineered T (CMV-TCR-T) cell therapy as the first-line pre-emptive therapy for patients with CMV reactivation after haploidentical peripheral blood SCT (PBSCT) was conducted in the Chinese PLA General Hospital. Six patients with CMV reactivation after haploidentical SCT were adoptively transferred by one to three doses of SCT donors-derived CMV-TCR-T cells. This trial was a dose-escalation study with doses ranging from 1×103 CMV-TCR-T cells/kg body weight per dose to 5×105 CMV-TCR-T cells/kg per dose. RESULTS: Except for the grade 1 cytokine release syndrome observed in one patient and mild fever in two patients, no other adverse events were observed. Four patients had response within a month after CMV-TCR-T cell infusion without the administration of any antiviral agents. The other two patients who initially did not respond to CMV-TCR-T cell therapy had salvage ganciclovir and foscarnet administration and then had rapid CMV clearance. The CMV-TCR-T cells displayed overall robust expansion and persistence in the peripheral blood after infusion. The CMV-TCR-T cells were first detected in the peripheral blood of these patients 3-7 days after the first dose of CMV-TCR-T infusion, rapidly expanded and persisted for at least 1-4 months, providing long-term protection against CMV reactivation. In one patient, the CMV-TCR-T cells started to expand even when the anti-graft-versus-host disease reagents were still being used, further indicating the proliferation potential of CMV-TCR-T cells. CONCLUSIONS: Our study first showed CMV-TCR-T cell as a highly feasible, safe and effective first-line pre-emptive treatment for CMV reactivation after haploidentical PBSCT. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT05140187).

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.

Reduced Risk of Chronic Graft-Versus-Host Disease (cGVHD) by Rabbit Anti-Thymocyte Globulin (ATG) in Patients Undergoing Matched Sibling Donor Transplantation in Hematological Malignancies.

BACKGROUND With the addition of anti-thymocyte globulin (ATG) to GVHD prophylaxis in patients undergoing transplantation of peripheral blood stem cells (PBSCT), the incidence of cGVHD decreases. However, the optimal dose and timing of ATG remain undetermined. MATERIAL AND METHODS In this historical controlled trial, data from 85 patients who had hematological malignancies and underwent matched sibling donor (MSD)-PBSCT were used to analyze the effectiveness of rabbit ATG (rATG) for prophylaxis of GVHD. Forty patients received 5 mg/kg rATG used for days -5 to -2, and 45 patients did not receive ATG. RESULTS All patients had successful engraftment except for 2 in the non-ATG group, who had platelet engraftment failure. The 2-year cumulative incidence of chronic GVHD (cGVHD) in the ATG group versus non-ATG group was 19.3% (95% CI, 8.4-33.6%) versus 61.4% (95% CI, 45.4-73.9%) (P<0.001), and in those with moderate to severe cGVHD it was 11.0% (95% CI, 3.4-23.6%) versus 31.8% (95% CI, 18.8-45.6%) (P=0.029), respectively. The 2-year cumulative incidence of non-relapse mortality and relapse (CIR) were 0% versus 15.5% (95% CI, 6.8-27.5%) (P=0.018), and 53.3% (95% CI, 35.6-68.1%) versus 26.7% (95% CI, 14.9-40.0%) (P=0.019), respectively. No differences were found in other survival outcomes. In the multivariate analysis, ATG was an independent protective factor for moderate to severe cGVHD (HR=0.314, 95% CI, 0.103-0.958, P=0.042), and was an independent poor risk factor for CIR (HR=2.337, 95% CI, 1.133-4.822, P=0.022). CONCLUSIONS ATG in our strategy was effective for prophylaxis of cGVHD, whereas the relapse rate was increased in patients with rATG.

High Risk of Recurrence of Malignancy Noted in Four-day rATG Regimen After Allogeneic PBSCT From Matched Sibling Donors.

Hitherto, the optimal timing of rabbit anti-thymocyte globulin (rATG) in matched sibling donor peripheral blood stem cell transplantation (MSD-PBSCT) remains to be elucidated. We wanted to evaluate the effect of a new timing strategy of rATG in MSD-PBSCT patients on transplantation outcomes. In this prospective single-arm phase 2 clinical trial, 45 consecutive MSD-PBSCT patients were enrolled from February 1, 2019, to January 31, 2021. The rATG was administered intravenously at a total dose of 5 mg/kg from day -5 to day -2 before graft infusion (4d-ATG group). Thirty-seven MSD-PBSCT patients receiving rATG at the same total dose of 5 mg/kg from day -5 to day -4 before graft infusion from December 1, 2014, to January 31, 2019 served as historical control (2d-ATG group). No graft failure occurred in either group. In the 4d-ATG group, median timing to neutrophil and platelet engraftment was 12 days. The cumulative incidences (CI) of grade 2-4 and grade 3-4 acute graft-versus-host disease (GVHD) at day 100 were 37.8% and 4.4%. The 2-year CIs of severe chronic GVHD and extensive chronic GVHD were 2.2% and 9.6%. The rates of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) reactivation at day 180 were 24.4% and 37.8%, respectively. No patients died of non-relapse causes. Twenty-one patients relapsed at a median of 203 days after transplantation, and the 2-year cumulative incidence of relapse (CIR) was 51.4%. The 2-year probabilities of overall survival (OS), disease-free survival (DFS), and GVHD-free and relapse-free survival (GRFS) were 72.4%, 48.6%, and 40.8%, respectively. There were no significant differences between the 4d-ATG group and 2d-ATG group with regard to timing of neutrophil and platelet engraftment, incidences of CMV reactivation, EBV reactivation, acute GVHD, chronic GVHD, probabilities of OS, and GRFS. The 2-year CIR was significantly increased, and the 2-year DFS was significantly reduced in 4d-ATG group compared with the control group (CIR: 51.4% versus 13.5%, P < .001; DFS: 48.6% versus 75.7%, P = .014). High CIR and worse DFS were noted in MSD-PBSCT receiving 4d-ATG regimen compared with historical control (2d-ATG regimen). Inappropriate rATG timing may increase the risk of relapse after MSD-PBSCT in patients with hematologic malignancies. © 2023 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

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.

Anti-thymocyte globulin (ATG) is often included in the conditioning regimen to prevent graft-versus-host disease (GVHD) in allogeneic hematopoietic cell transplantation (allo-HCT). However, the risk of virus reactivation increases significantly. We conducted a single-center prospective study to identify the optimal ATG exposure that ensures engraftment, effectively prevents acute GVHD, and reduces the risk of virus reactivation without increasing relapse of malignant diseases in haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). From September 2018 to June 2020, 106 patients (median age, 32 years) with malignant hematological diseases who received haplo-PBSCT for the first time were enrolled. All patients received 10 mg/kg rabbit ATG (thymoglobulin) divided for 4 days (days -5 to -2). Pre-transplant, post-transplant, and total areas under the concentration-time curve (AUCs) of active ATG were calculated. Total AUC of active ATG was shown to be the best predictor for virus reactivation and acute GVHD of grades II to IV or grades III and IV. The optimal total AUC range of active ATG was 100 to 148.5 UE/mL/day. The median time was 14 versus 13 days (P = .184) for neutrophil engraftment and 13 versus 13 days (P = .263) for platelet engraftment in the optimal and non-optimal AUC groups, respectively. The optimal AUC group showed a lower cumulative incidence of cytomegalovirus (CMV) reactivation and persistent CMV viremia than the non-optimal AUC group: 60.6% (95% confidence interval [CI], 48.3%-73.1%) versus 77.1% (95% CI, 64.5%-87.7%; P = .016) and 31.5% (95% CI, 21.2%-45.3%) versus 56.3% (95% CI, 42.9%-70.4%; P = .007), respectively. The cumulative incidence of persistent Epstein-Barr virus (EBV) viremia in the optimal AUC group was significantly lower than the non-optimal total AUC group: 33.1% (95% CI, 22.5%-46.8%) versus 52.6% (95% CI, 39.3%-67.2%; P = .048). However, there was no difference in EBV reactivation (P = .752). Similar outcomes were observed for grade II to IV and grade III and IV acute GVHD between the two groups: 48.6% (95% CI, 36.8%-62.0%) versus 37.0% (95% CI, 24.8%-52.5%; P = .113) and 10.4% (95% CI, 4.8%-21.7%) versus 4.2% (95% CI, 1.0%-15.6%; P = .234, respectively. Relapse, non-relapse mortality, and disease-free survival demonstrated no significant differences between the two groups. But, overall survival at 2 years tended to increase in the optimal AUC group: 75.7% (95% CI, 62.4%-84.8%) versus 57.8% (95% CI, 42.4%-70.4%; P = .061). These data support an optimal active ATG exposure of 110 to 148.5 UE/mL/day in haplo-PBSCT. Individualized dosing of ATG in allo-HCT might reduce the risk of virus reactivation and effectively prevent acute GVHD simultaneously.