[The Chinese consensus on the management of cytomegalovirus infection in allogeneic hematopoietic stem cell transplantation patients (2022)]

Role of letermovir therapeutic drug monitoring for cytomegalovirus prophylaxis in allogeneic hematopoietic stem cell transplantation recipients: a prospective study

PURPOSE

The role of therapeutic drug monitoring (TDM) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients receiving letermovir has not yet been clarified. This study is to explore letermovir trough concentration (Cmin) correlation with its clinical efficacy and adverse events, and factors affecting its plasma concentrations.

METHODS

A prospective, non-interventional study was performed in allo-HSCT recipients receiving letermovir prophylaxis. Plasma concentrations were determined using high-performance liquid chromatography-tandem mass spectrometry. Data analysis was performed using logistic regression, linear regression, and classification and regression tree (CART) models.

RESULTS

701 trough concentrations from 71 recipients were included, uncovering pronounced intra- and inter-individual variability in letermovir Cmin. During 24-week follow-up, CMV infection incidence was 16.4%. A significant correlation was identified between letermovir Cmin and its clinical efficacy, and the CART model showed an increased risk of CMV infection when Cmin ≤ 2731 ng/mL. However, no clear correlation was found between Cmin and adverse events. Gastrointestinal graft-versus-host disease, cyclosporine Cmin, gender, and concomitant medications, including mycophenolate mofetil, ondansetron, caspofungin, and methylprednisolone, may impact letermovir Cmin. Additionally, coadministration with cyclosporine injection significantly decreased median letermovir Cmin compared with cyclosporine capsules (2311 vs. 3386 ng/mL). Moreover, with the extension of time post-transplant, trough concentrations of both cyclosporine and letermovir significantly decreased.

CONCLUSION

TDM for letermovir may be beneficial in allo-HSCT recipients considering the variability in letermovir Cmin and its correlation with clinical efficacy. Moreover, drug interactions and the effects of changes in cyclosporine dosage forms or concentrations require careful monitoring for their effect on letermovir Cmin.

Expansion of effector memory Vδ2neg γδ T cells associates with cytomegalovirus reactivation in allogeneic stem cell transplant recipients

Background

Cytomegalovirus (CMV) reactivation is a significant concern following allogeneic stem cell transplantation. While previous research has highlighted the anti-CMV reactivation effect of γδ T cells in immunocompromised transplant patients, their characterization in recipients at high risk of CMV reactivation remains limited.

Methods

This study focused on D+/R+ recipients (where both donor and recipient are CMV seropositive) at high risk of CMV reactivation. We analyzed 28 patients who experienced CMV recurrence within 100 days post-allogeneic hematopoietic stem cell transplantation, along with 36 matched recipients who did not experience CMV recurrence. Clinical data from both groups were compared, and risk factors for CMV reactivation were identified. Additionally, CMV viral load was measured, and flow cytometric analysis was conducted to assess changes in peripheral blood γδ T cell proportions, subpopulation distribution, and differentiation status. We also analyzed the CDR3 repertoire of the TCR δ chain in different γδ T cell subsets. Functional analysis was performed by measuring the lysis of CMV-infected cells upon stimulation.

Results

CMV reactivation post-transplantation was associated with acute graft-versus-host disease (aGvHD) and reactivation of non-CMV herpesviruses. Notably, CMV reactivation led to sustained expansion of γδ T cells, primarily within the Vδ2neg γδ T cell subpopulation, with a trend toward differentiation from Naive to effector memory cells. Analysis of the δ chain CDR3 repertoire revealed a delay in the reconstitution of clonal diversity in Vδ2neg γδ T cells following CMV reactivation, while Vδ2pos T cells remained unaffected. Upon stimulation with CMV-infected MRC5 cells, the Vδ2neg γδ T cell subpopulation emerged as the primary effector cell group producing IFN-γ and capable of lysing CMV-infected cells. Moreover, our findings suggest that NKG2D is not necessary involved in Vδ2neg γδ T cell-mediated anti-CMV cytotoxicity.

Conclusion

This study provides novel insights into the role of γδ T cells in the immune response to CMV reactivation in transplantation recipients at high risk of CMV infection. Specifically, the Vδ2neg γδ T cell subpopulation appears to be closely associated with CMV reactivation, underscoring their potential role in controlling infection and reflecting CMV reactivation in HSCT patients.

Refractory cytomegalovirus infections in Chinese patients receiving allogeneic hematopoietic cell transplantation: a review of the literature

In the absence of prophylactic therapy, cytomegalovirus (CMV) viremia is a common complication following allogeneic hematopoietic cell transplantation (allo-HCT) and represents a significant cause of morbidity and mortality. Approximately 25% of allo-HCT happen in China, where the development and refinement of the 'Beijing protocol' has enabled frequent and increasing use of haploidentical donors. However, refractory CMV infection (an increase by >1 log10 in blood or serum CMV DNA levels after at least 2 weeks of an appropriately dosed anti-CMV medication) is more common among patients with haploidentical donors than with other donor types and has no established standard of care. Here, we review the literature regarding refractory CMV infection following allo-HCT in China.