High incidence but low mortality of EBV-reactivation and PTLD after alloHCT using ATG and PTCy for GVHD prophylaxis

Post-transplant lymphoproliferative disorders after allogeneic hematopoietic stem cell transplantation: a case report, meta-analysis, and systematic review

BACKGROUND

Post-transplant lymphoproliferative disorders (PTLD) are rare but severe complications that occur after solid organ or allogeneic hematopoietic stem cell transplantations (allo-HSCT), with rapid progression and high mortality. Primary central nervous system (CNS)-PTLD are rarely recognized histo-pathologically. In addition, the diagnostic value of the Epstein-Barr virus (EBV) DNA copies in CNS-PTLD remains poorly understood.

OBJECTIVES

We herein report a case of monomorphic EBV-associated CNS-PTLD (diffuse large B-cell lymphoma, DLBCL) after allo-HSCT and perform a meta-analysis to assess the efficacy of PTLD treatment strategies in recent years.

METHODS

We present the case report covering clinical manifestations, diagnosis, treatment, and outcomes of a patient with primary CNS-PTLD. Additionally, we include a systematic review and meta-analysis of the clinical characteristics of 431 patients with PTLD after allo-HSCT. We evaluate the main treatment options and outcomes of PTLD management, including rituximab, chemotherapies, and autologous or human leukocyte antigen (HLA)-matched EBV-specific cytotoxic T lymphocyte infusion (EBV-CTLs)/donor lymphocyte infusion (DLI).

RESULTS

The meta-analysis revealed an overall response rate of 69.0% for rituximab alone (95% CI: 0.47-0.84), 45.0% for rituximab plus chemotherapies (95% CI: 0.15-0.80), and 91.0% for rituximab plus EBV-CTLs/DLI (95% CI: 0.83-0.96). The complete response (CR) rate after treatments for PTLD was 67.0% (95% CI: 0.56-0.77). Moreover, the 6-month and 1-year overall survival (OS) rate was 64.0% (95% CI: 0.31-0.87) and 49.0% (95% CI: 0.31-0.68), respectively.

CONCLUSIONS

This case highlighted the urgent need for effective, low-toxic treatment regimens for CNS-PTLD. Our meta-analysis suggested that rituximab combined with EBV-CTLs/DLI could be a favorable strategy for the management of PTLD after allo-HSCT.

Epstein-Barr Virus Monitoring after an Allogeneic Hematopoietic Stem Cell Transplant: Review of the Recent Data and Current Practices in Canada

Epstein-Barr virus-related post-transplantation lymphoproliferative disorder (EBV-PTLD) is a serious complication following hematopoietic stem cell transplantation (HSCT). A pre-emptive strategy using rituximab, which aims to manage patients early at the time of EBV reactivation to avoid PTLD, has been recommended by the most recent ECIL-6 guidelines in 2016. However, there is still a great heterogeneity of viral-load monitoring protocols, targeted patient populations, and pre-emptive treatment characteristics between centers, making precise EBV monitoring recommendations difficult. We conducted a literature review from the most recent publications between 1 January 2015 and 1 August 2023, to summarize the emerging data on EBV-PTLD prevention strategies in HSCT recipients, including the EBV-DNA threshold and use of rituximab. We also present the results of a survey of current practices carried out in 12 of the main HSCT centers across Canada. We confirm that pre-emptive rituximab remains an efficient strategy for EBV-PTLD prevention. However, there is an urgent need to perform prospective, randomized, multicentric trials with larger numbers of patients reflecting current practices to determine the best clinical conduct with regards to rituximab dosing, timing of treatment, and criteria to initiate treatments. Longer follow-ups will also be necessary to assess patients' long-term outcomes.

Posttransplant cyclophosphamide beyond haploidentical transplantation

Posttransplant cyclophosphamide (PTCy) has practically revolutionized haploidentical (Haplo) hematopoietic cell transplantation (HCT). Comparisons between Haplo with PTCy and unrelated donor (URD) with conventional graft-versus-host disease (GVHD) prophylaxis have shown comparable overall survival with lower incidences of GVHD with Haplo/PTCy and led to the following question: is it PTCy so good that can be successfully incorporated into matched related donor (MRD) and URD HCT? In this review, we discuss other ways of doing PTCy, PTCy in peripheral blood haploidentical transplants, PTCy in the context of matched related and matched unrelated donors, PTCy with mismatched unrelated donors, and PTCy following checkpoint inhibitor treatment. PTCy is emerging as a new standard GVHD prophylaxis in haploidentical, HLA-matched, and -mismatched HCT.

Hematopoietic stem cell transplantation and the noncytomegalovirus herpesviruses

Although hematopoietic stem cell transplantation (HSCT) and other cellular therapies have significantly improved outcomes in the management of multiple hematological and nonhematological malignancies, the resulting impairment in humoral and cellular response increases the risk for opportunistic infection as an undesirable side effect. With their ability to establish latent infection and reactivate when the host immune system is at its weakest point, the Herpesviridae family constitutes a significant proportion of these opportunistic pathogens. Despite recent advancements in preventing and managing herpesvirus infections, they continue to be a common cause of significant morbidity and mortality in transplanted patients. Herein, we aim to provide and update on herpesvirus other than cytomegalovirus (CMV) affecting recipients of HSCT and other cellular therapies.

Does PTCY increase the risk of infections?

PTCY has been mainly used in haploidentical transplant (haploHSCT), but its use in matched donors allowed better evaluation of infectious risk conferred separately by PTCY or donor type. PTCY increased the risk of bacterial infections, both in haploidentical and matched donors, mainly pre-engraftment bacteremias. Bacterial infections, particularly due to multidrug-resistant Gram-negatives, were main causes of infection-related deaths. Higher rates of CMV and other viral infections were reported, mainly in haploHSCT. The role of donor might be more important than the role of PTCY. PTCY increased the risk of BK virus associated hemorrhagic cystitis, and seemed associated with higher risk of respiratory viral infections. Fungal infections were frequent in haploHSCT PCTY cohorts without mold active prophylaxis, but the exact role of PTCY needs to be established. Infections appear to be increased in patients receiving PTCY, although the exact role of GvHD prophylaxis and donor type can only be assessed in prospective trials.

Important Considerations in the Diagnosis and Management of Post-transplant Lymphoproliferative Disorder

PURPOSE OF REVIEW

A relative lack of molecular and clinical studies compared to other lymphoid cancers has historically made it difficult to determine optimal management approaches in post-transplant lymphoproliferative disorder (PTLD). We sought to better define the "state of the science" in PTLD by examining recent advances in risk assessment, genomic profiling, and trials of PTLD-directed therapy.

RECENT FINDINGS

Several major clinical trials highlight risk-stratified sequential therapy incorporating rituximab with or without chemotherapy as a rational treatment strategy in patients with CD20+ PTLD who do not respond to reduction of immunosuppression alone. Epstein Barr virus (EBV)-targeted cytotoxic lymphocytes are a promising approach in patients with relapsed/refractory EBV+ PTLD, but dedicated clinical trials should determine how autologous chimeric antigen receptor T cell therapy (CAR-T) may be safely administered to PTLD patients. Sequencing studies underscore the important effect of EBV infection on PTLD pathogenesis, but comprehensive genomic and tumor microenvironment profiling are needed to identify biomarkers that predict response to treatment in this clinically heterogeneous disease.

Epstein-Barr Virus Reactivation After Paediatric Haematopoietic Stem Cell Transplantation: Risk Factors and Sensitivity Analysis of Mathematical Model

Epstein-Barr virus (EBV) establishes a lifelong latent infection in healthy humans, kept under immune control by cytotoxic T cells (CTLs). Following paediatric haematopoetic stem cell transplantation (HSCT), a loss of immune surveillance leads to opportunistic outgrowth of EBV-infected cells, resulting in EBV reactivation, which can ultimately progress to post-transplant lymphoproliferative disorder (PTLD). The aims of this study were to identify risk factors for EBV reactivation in children in the first 100 days post-HSCT and to assess the suitability of a previously reported mathematical model to mechanistically model EBV reactivation kinetics in this cohort. Retrospective electronic data were collected from 56 children who underwent HSCT at Great Ormond Street Hospital (GOSH) between 2005 and 2016. Using EBV viral load (VL) measurements from weekly quantitative PCR (qPCR) monitoring post-HSCT, a multivariable Cox proportional hazards (Cox-PH) model was developed to assess time to first EBV reactivation event in the first 100 days post-HSCT. Sensitivity analysis of a previously reported mathematical model was performed to identify key parameters affecting EBV VL. Cox-PH modelling revealed EBV seropositivity of the HSCT recipient and administration of anti-thymocyte globulin (ATG) pre-HSCT to be significantly associated with an increased risk of EBV reactivation in the first 100 days post-HSCT (adjusted hazard ratio (AHR) = 2.32, P = 0.02; AHR = 2.55, P = 0.04). Five parameters were found to affect EBV VL in sensitivity analysis of the previously reported mathematical model. In conclusion, we have assessed the effect of multiple covariates on EBV reactivation in the first 100 days post-HSCT in children and have identified key parameters in a previously reported mechanistic mathematical model that affect EBV VL. Future work will aim to fit this model to patient EBV VLs, develop the model to account for interindividual variability and model the effect of clinically relevant covariates such as rituximab therapy and ATG on EBV VL.

Epstein-Barr virus posttransplant lymphoproliferative disorder: update on management and outcomes

PURPOSE OF REVIEW

Management of Epstein-Barr virus posttransplant lymphoproliferative disorder (EBV PTLD) is complex, involving risk stratification, prevention and/or preemptive measures involving monitoring EBV DNAemia and balancing treatment options, using a combination of reduction of immune suppression, anti-B cell therapy, and cytotoxic T lymphocytes (CTLs).

RECENT FINDINGS

The highest risk factor for the development of EBV PTLD in hematopoietic cell transplant (HCT) remains T cell depletion, with increasing use of antithymocyte globulin (ATG) or alemtuzumab in conditioning. In solid organ transplantation (SOT), the incidence of PTLD is highest among EBV seronegative recipients who are at risk for primary EBV infection following transplant in the first 12 months. Prevention is a critical component of the management of EBV PTLD. Although preemptive therapy remains standard of care, there continues to be heterogenicity and debate over the optimal choice of EBV DNA quantification and the threshold to use. Novel therapies such as donor-derived multipathogen and EBV specific CTLs for the prevention and third party CTLs for the treatment of EBV PTLD are promising, with rapidly expanding evidence, including large scale Phase III trials currently underway.

SUMMARY

With an increasing number of risk groups for developing EBV PTLD in HCT and SOT, management strategies using prophylaxis or preemptive therapy remain standard of care, however the use of prophylactic or preemptive EBV specific or multipathogen CTLs show promising results and safety profiles.

Epstein-Barr virus-related lymphoproliferative disorders in T-cell repleted haploidentical transplantation with post-transplant cyclophosphamide

EBV-associated lymphoproliferative disorders (LPDs) are common in hematopoietic stem cell transplantation (HSCT) with T-cell-depleted grafts, but are extremely rare in HSCT patients with T-cell-replete grafts with post-transplant cyclophosphamide (PTCy). Here we present the cases of two pediatric patients who developed EBV-related LPD after T-cell-replete haplo-HSCT with PTCy. One of these is the first reported case of EBV-positive mucocutaneous ulcer (EBVMCU) developing after PTCy. EBV-related diseases are rare in T-cell-replete haplo-HSCT patients with PTCy. However, in patients with risk factors, it is reasonable to screen for EBV viremia for LPD.

EBV-PTLD in a patient after haploidentical stem-cell transplantation with post-transplant cyclophosphamide

Here, we describe the case of a male patient with Epstein-Barr virus post-transplantation lymphoproliferative disorder (EBV-PTLD), which developed 18 months after a haploidentical hematopoietic stem cell transplantation (haplo-HSCT) and the administration of post-transplant cyclophosphamide (PTCy). Of note, no anti-thymoglobulin was used in the entire clinical course. Prior to the onset of EBV-PTLD, the patient had pulmonary chronic graft-versus-host disease and was treated with prednisolone and tacrolimus. After stopping immunosuppressive therapy, he was diagnosed with EBV-positive infectious mononucleosis PTLD, and EBV-associated hemophagocytic syndrome; therefore, dexamethasone and rituximab monotherapies were administered. After four courses of rituximab, EBV-DNA was no longer detected in the peripheral blood, and the patient's laboratory data improved. Overall, this study highlights the need to predict the risk factors associated with the development of EBV-PTLD in transplanted patients after haplo-HSCT with PTCy.