Mpox virus is an emergent human pathogen. While it is less lethal than smallpox, it can still cause significant morbidity and mortality. In this review, we explore 3 antiviral agents with activity against mpox and other orthopoxviruses: cidofovir, brincidofovir, and tecovirimat. Cidofovir, and its prodrug brincidofovir, are inhibitors of DNA replication with a broad spectrum of activity against multiple families of double-stranded DNA viruses. Tecovirimat has more specific activity against orthopoxviruses and inhibits the formation of the extracellular enveloped virus necessary for cell-to-cell transmission. For each agent, we review basic pharmacology, data from animal models, and reported experience in human patients.

Background: Cytomegalovirus (CMV) reactivation is one of the most common infectious complications after allogeneic hematopoietic cell transplant (HCT) and may result in significant morbidity and mortality. Primary prophylaxis with letermovir demonstrated a reduction in clinically significant CMV infections (CS-CMVi) in clinical trials of CMV-seropositive HCT recipients. This study aims at exploring the effect of primary letermovir prophylaxis in this population on the incidence and outcomes of refractory or resistant CMV infections. Methods: This is a single-center, retrospective cohort study of 537 consecutive CMV-seropositive allogeneic HCT recipients cared for between March 2016 and October 2018. Baseline demographics, HCT characteristics, CMV infections, treatment, and mortality data were collected from the electronic medical record. CMV outcomes were defined according to the recently standardized definitions for clinical trials. Characteristics and outcomes were assessed according to receipt of primary letermovir prophylaxis. Results: Of 537 patients identified, 123 received letermovir for primary prophylaxis during the first 100 days after HCT; 414 did not. In a multivariate analysis, primary prophylaxis with letermovir was associated with reductions in CS-CMVi (hazard ratio [HR] 0.26; 95% confidence interval [CI], 0.16–0.41), CMV end-organ disease (HR 0.23; 95% CI, 0.10–0.52), refractory or resistant CMV infection (HR 0.15; 95% CI, 0.04–0.52), and nonrelapse mortality at week 48 (HR 0.55; 95% CI, 0.32–0.93). There was neither resistant CMV nor CMV-related mortality in the primary letermovir prophylaxis group. Conclusions: Primary letermovir prophylaxis effectively prevents refractory or resistant CMV infections and decreases nonrelapse mortality at week 48, as well as CS-CMVi and CMV disease after allogeneic HCT.

Background: Patients with B-cell lymphoma and acute lymphoblastic leukemia (ALL) who receive chimeric antigen receptor T-cell (CAR-T) therapy may experience clinically significant cytomegalovirus infection (CS-CMVi). However, risk factors for CS-CMVi are not well defined. The aims of our study were to identify risk factors for CS-CMVi and the association between CS-CMVi and nonrelapse mortality (NRM) in lymphoma and ALL patients after CAR-T therapy. Methods: We performed a retrospective single-center cohort analysis of CAR-T recipients between January 2018 and February 2021 for treatment of lymphoma and ALL. We collected data on demographics, oncologic history, CAR-T therapy–related complications, and infectious complications within 1 year of therapy. Results: Of 230 patients identified, 22 (10%) had CS-CMVi. At 1 year following CAR-T therapy, 75 patients (33%) developed relapsed disease and 95 (41%) died; NRM at 1 year was 37%. On Cox regression analysis, Asian or Middle Eastern race (adjusted hazard ratio [aHR], 13.71 [95% confidence interval {CI}, 5.41–34.74]), treatment of cytokine release syndrome/immune effector cell–associated neurotoxicity syndrome with steroids (aHR, 6.25 [95% CI, 1.82–21.47]), lactate dehydrogenase at time of CAR-T therapy (aHR, 1.09 [95% CI, 1.02–1.16]), and CMV surveillance (aHR, 6.91 [95% CI, 2.77–17.25]) were independently associated with CS-CMVi. CS-CMVi was independently associated with NRM at 1 year after CAR-T therapy (odds ratio, 2.49 [95% CI, 1.29–4.82]). Conclusions: Further studies of immunologic correlatives and clinical trials to determine the efficacy of prophylactic strategies are needed to understand the role of CS-CMVi and post–CAR-T mortality.

In this narrative review, we explore the burden and risk factors of various herpesvirus infections in patients receiving chimeric antigen receptor T-cell (CAR-T) therapy or bispecific antibodies (BsAb) for the treatment of hematologic malignancies. Antiviral prophylaxis for herpes simplex/varicella zoster viruses became part of the standard of care in this patient population. Breakthrough infections may rarely occur, and the optimal duration of prophylaxis as well as the timing of recombinant zoster immunization remain to be explored. Clinically significant cytomegalovirus (CMV) infections can affect up to 10% of patients after CAR-T, depending on the CAR-T product target, post-CAR-T complications such as cytokine release syndrome and the need for glucocorticoid therapy. Surveillance and prophylactic strategies for CMV need to be developed, whereas the risk factors for and the burden of CMV infections after BsAb are not yet well-defined. Human herpes virus 6 reactivation and end organ disease such as encephalitis are rarely reported after CAR-T and have not yet been reported after BsAb; additional research is needed.