Natural History of Epstein-Barr Virus Replication and Viral Load Dynamics after Alemtuzumab-Based Allogeneic Stem Cell Transplantation

Efficacy of Letermovir for Cytomegalovirus Prophylaxis Following Alemtuzumab T-Cell Depleted Allogeneic Hematopoietic Stem Cell Transplant

In vivo T-cell depletion (TCD) using alemtuzumab decreases the risk of Graft vs Host Disease (GvHD) in recipients of allogeneic hematopoietic stem cell transplant (allo-HSCT). However, this approach increases the risk of infections post-allo-HSCT, including Cytomegalovirus (CMV). Letermovir is approved for the use in CMV prophylaxis post-allo-HSCT. Few studies have investigated the efficacy of letermovir in patients receiving alemtuzumab. This is a single-center retrospective study describing our institutional experience using letermovir in recipients of alemtuzumab TCD allo-HSCT from unrelated donors (URD). The primary outcome was the cumulative incidence of significant CMV infection (defined as viremia leading to preemptive antiviral therapy or CMV disease) within 100 days post-transplant. Secondary outcomes included the cumulative incidence of acute GvHD (grade ≥ 2), the cumulative incidence of extensive chronic GvHD, and overall survival. A total of 84 alemtuzumab TCD URD allo-HSCT recipients were included in the analysis, 30 of whom received letermovir (letermovir group) and 54 who did not receive letermovir (control group). The median age was 59 years (range: 26-75 years) and 55.5 years (range: 20-73 years) in the letermovir and control group, respectively. Most recipients (66.7%) in both groups received unrelated matched allografts, and myeloid neoplasms were the most common indication for allo-HSCT. A significantly lower cumulative incidence of significant CMV infection within 100 days was seen in the letermovir group compared to the control group (10.0% [95% CI: 2.5-23.9%] versus 55.6% [95% CI: 41.2-67.8%], P < .0001). There was no statistically significant difference in the incidence of acute GvHD (grade ≥ 2) or overall survival between the 2 groups. However, lower rates of extensive chronic GvHD were noted in the letermovir group (10.5% [95% CI: 2.6-24.9%] versus. 36.5% [95% CI: 23.6-49.5%], P = .0126). These results demonstrate the efficacy of letermovir in decreasing the rates of clinically significant CMV infection in patients undergoing alemtuzumab T-cell depleted 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.

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.