Reconstitution of cytomegalovirus-specific T-cell immunity following unmanipulated haploidentical allogeneic hematopoietic stem cell transplantation with posttransplant cyclophosphamide

T-Cell Immune Responses in Newborns and Long-Term Sequelae in Congenital Cytomegalovirus Infection (CYTRIC Study)

OBJECTIVE

To assess the role of T-lymphocyte immune responses in newborns with congenital cytomegalovirus (CMV) infection (cCMV) and their potential association with the development of long-term sequelae.

STUDY DESIGN

A multicenter, prospective study from 2017 to 2022 was conducted across eight hospitals in Spain. Blood samples were collected within the first month of life from neonates diagnosed with cCMV. Intracellular cytokine staining was employed to evaluate the presence of CMV-specific interferon-gamma (IFN-γ)-producing CD8+ and CD4+ T lymphocytes (CMV-IFN-γ-CD8+ / CD4+) using flow cytometry. The development of sequelae, including hearing loss and neurologic impairment, was assessed during follow-up.

RESULTS

In total, 64 newborns were included; 42 infants (65.6%) had symptomatic cCMV. The median age at last follow-up visit was 25.3 months (IQR 20.1-34.4). Eighteen infants had long-term sequelae (28.1%), predominantly hearing loss (20.3%) and neurologic disorders (15.6%). No relationship was observed between total count or percentage of CMV-specific IFN-γ-CD8+ or CD4+ lymphocytes and long-term sequelae. Multivariable analysis demonstrated an association between lower total lymphocyte count and long-term sequelae (aOR 0.549, 95% CI: 0.323-0.833), which requires further study.

CONCLUSIONS

CMV-specific IFN-γ-CD4+ and CD8+ T-lymphocyte responses in neonates with cCMV were not predictive of long-term sequelae.

Impact of cytomegalovirus immunodominant HLA-I donor-recipient matching on the incidence and features of virus DNAemia and virus-specific T-cell immune reconstitution in unmanipulated haploidentical hematopoietic stem cell transplantation

BACKGROUND

We investigated whether donor-recipient mismatch involving one or more cytomegalovirus (CMV) immunodominant (ID) human leukocyte antigen (HLA)-I alleles may impact on the degree of CMV pp65/immediate-early 1 (IE-1) T-cell reconstitution and the incidence of CMV DNAemia in patients undergoing unmanipulated haploidentical hematopoietic stem cell transplantation with high-dose posttransplant cyclophosphamide (PT/Cy-haplo).

METHODS

Multicenter observational study including 106 consecutive adult PT/Cy-haplo patients (34 CMV ID HLA-I matched and 72 mismatched). A real-time PCR was used for plasma CMV DNA load monitoring. Enumeration of CMV-specific (pp65/IE-1) interferon (IFN)-γ-producing T cells from several patients was performed by flow cytometry by days +30, +60, +90 and +180 after transplantation.

RESULTS

The cumulative incidence of CMV DNAemia, clinically significant CMV DNAemia episodes (cs-CMVi), and recurrent CMV DNAemia was comparable across CMV ID HLA-I matched and mismatched patients (71.8% vs. 80.9%, p = .95; 40.7% vs. 44.2%, p = .85; 16.4% vs. 28.1%; p = .43, respectively). The percentage of patients exhibiting detectable CMV-specific IFN-γ-producing T-cell responses (either CD8⁺ or CD4⁺ ) was similar across groups; nevertheless, significantly higher CMV-specific CD8⁺ T-cell counts were enumerated in the CMV ID HLA-I matched compared to mismatched patients by day +60 (p = .04) and +180 (p = .016) after transplantation.

CONCLUSION

CMV ID HLA-I matching may impact on the magnitude of CMV-pp65/IE-1-specific CD8⁺ T-cell reconstitution; yet, this effect seemed not to have an impact on the incidence of initial, recurrent CMV DNAemia, or cs-CMVi.

Features of cytomegalovirus DNAemia and virus-specific T-cell responses in allogeneic hematopoietic stem-cell transplant recipients during prophylaxis with letermovir

BACKGROUND

There is scarce information on the natural kinetics of cytomegalovirus (CMV) DNAemia and dynamics of CMV-specific T-cell reconstitution in allogeneic hematopoietic transplant recipients (allo-HSCT) undergoing letermovir (LMV) prophylaxis.

METHODS

Twelve adult CMV-seropositive high-risk recipients (median age, 53 years; 9 males/3 females) undergoing LMV prophylaxis and 13 non-LMV allo-HSCT controls (median age, 58 years; 7 males/6 females) were included. CMV DNAemia in plasma was monitored by real-time polymerase chain reaction. Preemptive antiviral therapy (PET) was administered upon detection of ≥1500 IU/ml. CMV-specific interferon-gamma (IFN-γ)-producing CD8⁺ and CD4⁺ T cells were enumerated by flow cytometry around days +30, +60, and +90 after allo-HSCT. Ex vivo experiments assessing of the potential effect of LMV on CMV-specific T-cell expansion in a single CMV-seropositive donor were also conducted.

RESULTS

Five LMV patients (41.6%) developed CMV DNAemia that cleared spontaneously. Four patients (33.3%) developed CMV DNAemia after LMV cessation, of which two required PET. Nine non-LMV patients (69.2%) developed CMV DNAemia (five required PET). The percentage of LMV and non-LMV patients exhibiting detectable CMV-specific T-cell responses was comparable (7/10 vs. 10/13; p = .71). Nevertheless, median CMV-specific CD4⁺ and CD8⁺ T-cell counts were lower in LMV patients by days +60 (p = .006 and .02, respectively) and +90 (p = .08 and .02). Ex vivo, CMV-specific CD8⁺ T cells expanded to the same level either in the presence (19.8%) or in the absence of LMV (20.6%).

CONCLUSIONS

In our series, episodes of CMV DNAemia in LMV patients cleared spontaneously. A diminished degree of CMV-specific T-cell reconstitution in LMV patients compared to non-LMV patients was observed.

Relationship between certain HLA alleles and the risk of cytomegalovirus reactivation following allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Evidence is emerging to support an association between certain HLA alleles and the risk of cytomegalovirus (CMV) reactivation following allogeneic HSCT (allo-HSCT). The primary aim of this study was to identify HLA alleles associated with resistance or susceptibility to CMV reactivation.

METHODS

We studied 586 adults who underwent allo-HSCT for high-risk hematological malignancies. High resolution HLA typing data was available for recipient and donor. HLA Class I and II alleles observed at a frequency of > 5% in our population, were included in the analysis. A CMV viremia level of more than 200 IU/ml on weekly monitoring was considered to be indicative of CMV reactivation.

RESULTS

The median follow-up time in surviving patients was 21 months (range 4-74 months). The cumulative incidence of CMV reactivation at 6 months in the entire cohort was 55% (95% CI 50.8%-59.2%). Mismatched donor, increasing recipient age, occurrence of AGVHD and recipient CMV seropositivity were associated with increased risk of CMV reactivation. HLA B*07:02 (HR 0.59, 95% CI 0.40-0.83) was associated with decreased risk of CMV reactivation. Patients who developed CMV reactivation had a lower incidence of relapse, higher transplant related mortality (TRM) and lower overall survival (OS) compared to those without CMV reactivation. There was an adverse correlation of OS and TRM with increasing numbers of CMV reactivations.

CONCLUSION

We observed that HLA B*07:02 was associated with decreased risk of CMV reactivation. CMV reactivation was associated with lower relapse post-transplant, but this did not translate into a survival benefit due to higher transplant related mortality. This article is protected by copyright. All rights reserved.

Cytomegalovirus in Haematological Tumours

The exquisite coupling between herpesvirus and human beings is the result of millions of years of relationship, coexistence, adaptation, and divergence. It is probably based on the ability to generate a latency that keeps viral activity at a very low level, thereby apparently minimising harm to its host. However, this evolutionary success disappears in immunosuppressed patients, especially in haematological patients. The relevance of infection and reactivation in haematological patients has been a matter of interest, although one fundamentally focused on reactivation in the post-allogeneic stem cell transplant (SCT) patient cohort. Newer transplant modalities have been progressively introduced in clinical settings, with successively more drugs being used to manipulate graft composition and functionality. In addition, new antiviral drugs are available to treat CMV infection. We review the immunological architecture that is key to a favourable outcome in this subset of patients. Less is known about the effects of herpesvirus in terms of mortality or disease progression in patients with other malignant haematological diseases who are treated with immuno-chemotherapy or new molecules, or in patients who receive autologous SCT. The absence of serious consequences in these groups has probably limited the motivation to deepen our knowledge of this aspect. However, the introduction of new therapeutic agents for haematological malignancies has led to a better understanding of how natural killer (NK) cells, CD4+ and CD8+ T lymphocytes, and B lymphocytes interact, and of the role of CMV infection in the context of recently introduced drugs such as Bruton tyrosine kinase (BTK) inhibitors, phosphoinosytol-3-kinase inhibitors, anti-BCL2 drugs, and even CAR-T cells. We analyse the immunological basis and recommendations regarding these scenarios.

CMV Infection and CMV-Specific Immune Reconstitution Following Haploidentical Stem Cell Transplantation: An Update

Haploidentical stem cell transplantation (haploSCT) has advanced to a common procedure for treating patients with hematological malignancies and immunodeficiency diseases. However, cure is seriously hampered by cytomegalovirus (CMV) infections and delayed immune reconstitution for the majority of haploidentical transplant recipients compared to HLA-matched stem cell transplantation. Three major approaches, including in vivo T-cell depletion (TCD) using antithymocyte globulin for haploSCT (in vivo TCD-haploSCT), ex vivo TCD using CD34 + positive selection for haploSCT (ex vivo TCD-haploSCT), and T-cell replete haploSCT using posttransplant cyclophosphamide (PTCy-haploSCT), are currently used worldwide. We provide an update on CMV infection and CMV-specific immune recovery in this fast-evolving field. The progress made in cellular immunotherapy of CMV infection after haploSCT is also addressed. Groundwork has been prepared for the creation of personalized avenues to enhance immune reconstitution and decrease the incidence of CMV infection after haploSCT.

Severe infections and infection-related mortality in a large series of haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide

Severe infections and their attributable mortality are major complications in recipients of allogeneic hematopoietic stem cell transplantation (alloSCT). We herein report 236 adult patients who received haploSCT with PTCy. The median follow-up for survivors was 37 months. The overall incidence of bloodstream infections by gram-positive and gram-negative bacteria at 37 months was 51% and 46%, respectively. The incidence of cytomegalovirus infection was 69%, while Epstein Barr virus infections occurred in 10% of patients and hemorrhagic cystitis in 35% of cases. Invasive fungal infections occurred in 11% at 17 months. The 3-year incidence of infection-related mortality was 19%. The median interval from transplant to IRM was 3 months (range 1–30), 53% of IRM occurred >100 days post-haploSCT. Risk factors for IRM included age >50 years, lymphoid malignancy, and developing grade III-IV acute GvHD. Bacterial infections were the most common causes of IRM (51%), mainly due to gram-negative bacilli BSI. In conclusion, severe infections are the most common causes of NRM after haploSCT with PTCy, with a reemergence of gram-negative bacilli as the most lethal pathogens. More studies focusing on the severe infections after haploSCT with PTCy and differences with other types of alloSCT in adults are clearly warranted.

Post-transplantation Cyclophosphamide, Tacrolimus and Low-Dose ATG as GVHD Prophylaxis for Allogeneic Peripheral Stem Cell Transplantation for Adult Patients With Lymphoid Malignancies: A Single Arm Phase II Study

The PT-Cy was considered as one of the mainstay protocol for graft verus host disease (GVHD) prophylaxis. Recent study demonstrated that PT-Cy combined with other immunosuppressants could further reduce the incidence of GVHD and improve the GVHD and relapse free survival (GRFS). In this prospective phase II study, we evaluated the effect of a new GVHD prophylaxis consist of PT-Cy combined with tacrolimus and low dose anti-thymoglobulin (ATG). A total of 23 patients were enrolled including 20 patients with acute lymphoblastic leukemia (ALL) and three patients with T cell lymphoma. The median age was 29 years (range, 16~58 years). Patients with HLA-matched related donor (MSD, n=7) received PT-Cy combined with tacrolimus, while patients with HLA matched unrelated (MUD, n = 2) or haplo-identical (Haplo, n = 14) donor received additional ATG at 2.5 mg/kg on day 15 or day 22 after engraftment of neutrophils. As to the acute GVHD (aGVHD), only three patients developed grade I (n = 1) or grade II (n = 2) aGVHD with 100-day incidence of all aGVHD and II-IV aGVHD at 13.0 ± 5.1% and 9.1 ± 6.1% respectively. Only two patients had mild and one had moderate chronic GVHD (cGVHD), with 1-year incidence of cGVHD and moderate/severe cGVHD at 15.2 ± 8.7% and 4.6 ± 4.4% respectively. A high incidence of CMV reactivation was documented (14/16 with MUD/Haplo donor and 2/7 with MSD) with only 1 CMV disease documented. There were two EBV reactivation without post-transplantation lymphoproliferative disease (PTLD) documented. With a median follow-up of 303 days (range, 75~700 days), three patients relapsed leading to 1-year cumulative incidence of relapse (CIR) at 12.8 ± 9.2%. Only one patient died of CMV pneumonia on day 91 with both 100-day and 1-year non-relapse mortality (NRM) at 4.6 ± 4.4%. The 1-year overall survival (OS), event-free survival (EFS) and GRFS were 95.5 ± 4.4%, 82.6 ± 9.5%, and 68.0 ± 11.3% respectively. Based on Simon's stage II design, our primary data showed that the PT-Cy+tacrolimus ± ATG protocol was promising in preventing aGVHD and cGVHD, which may translate into low NRM without increased CIR. Further clinical trial with large number of patients should be warranted. This trial was registered at www.clinicaltrials.gov as #NCT04118075.