Brincidofovir as a Salvage Therapy in Controlling Adenoviremia in Pediatric Recipients of Hematopoietic Stem Cell Transplant

Impact of Respiratory Viral Infections in Transplant Recipients

Respiratory viral infections (RVIs) are among the leading cause of morbidity and mortality in pediatric hematopoietic stem cell transplant (HCT) and solid organ transplant (SOT) recipients. Transplant recipients remain at high risk for super imposed bacterial and fungal pneumonia, chronic graft dysfunction, and graft failure as a result of RVIs. Recent multicenter retrospective studies and prospective studies utilizing contemporary molecular diagnostic techniques have better delineated the epidemiology and outcomes of RVIs in pediatric transplant recipients and have advanced the development of preventative vaccines and treatment interventions in this population. In this review, we will define the epidemiology and outcomes of RVIs in SOT and HSCT recipients, describe the available assays for diagnosing a suspected RVI, highlight evolving management and vaccination strategies, review the risk of donor derived RVI in SOT recipients, and discuss considerations for delaying transplantation in the presence of an RVI.

Adenovirus Infection in Hematopoietic and Solid Organ Paediatric Transplant Recipients: Treatment, Outcomes, and Use of Cidofovir

BACKGROUND

human adenovirus (hAdV) infection constitutes an important cause of morbidity and mortality in transplant recipients, due to their immune status. Among drugs currently available, cidofovir (CDF) is the most prescribed.

METHODS

Retrospective study of hAdV infection in paediatric transplant recipients from a tertiary paediatric centre, describing characteristics, management, and outcomes, and focused on the role of CDF.

RESULTS

49 episodes of infection by hAdV were detected during a four-year period: 38 episodes in patients that received allogeneic hematopoietic stem cell transplantation (77.6%) and 11 in solid organ transplant recipients (22.4%). Twenty-five patients (52.1%) were symptomatic, presenting mainly fever and/or diarrhoea. CDF was prescribed in 24 patients (49%), with modest results. CDF use was associated with the presence of symptoms resulting in lower lymphocyte count, paediatric intensive care unit admission, and high viral load. Other therapeutic measures included administration of intravenous immunoglobulin, reducing immunosuppression, and T-lymphocyte infusion. Despite treatment, 22.9% of patients did not resolve the infection and there were three deaths related to hAdV infection. All-cause mortality was 16.7% (8 episodes) by 30 days, and 32.7% (16 episodes) by 90 days, of which, 3 episodes (3/16, 18.8%) were attributed to hAdV directly.

CONCLUSIONS

hAdV infection had high morbidity and mortality in our series. CDF use is controversial, and available therapeutic options are limited. Transplant patients with low lymphocyte count are at higher risk of persistent positive viremias, and short-term survival of these patients was influenced by the resolution of hAdV infection.

Risks and outcomes of adenovirus disease in pediatric hematopoietic stem cell transplant recipients-Comparison of current antiviral treatment options

BACKGROUND

Adenovirus disease (ADVd) is a significant burden in pediatric hematopoietic stem cell transplant (HSCT) recipients. However, current knowledge of risk factors associated with poor clinical outcome and the effectiveness of antiviral therapy are not well understood. This study determined the relationship between transplant characteristics and risk of ADVd and also compared time to resolution of disease between pediatric patients who did and did not receive antiviral therapy.

METHODS

We conducted a retrospective, single-center cohort study of pediatric patients undergoing HSCT at Duke University (2005-2016). Cases of ADVd were defined a priori using a classification tool. Cox proportional hazards (CPH) regression models were used to compare the hazard of ADVd between HSCT recipients differing by type of transplant and type of conditioning regimen. The hazard of time to resolution of ADVd by antiviral therapy (cidofovir, brincidofovir, both, or neither) was compared.

RESULTS

Ninety-three of 830 subjects had ADVd post-HSCT (11.2%). Umbilical cord transplant (UCT) recipients had 2.30 (95% CI 1.57, 6.90, P = .002) higher hazard of developing ADVd compared to non-cord allogeneic transplants, and 6.30 higher (95% CI 2.70, 19.61, P < .001) hazard compared to autologous transplants. Subjects who did not receive antiviral therapy experienced earlier resolution of ADVd compared to subjects who received therapy, even after adjusting for subjects with disseminated disease (HR [95% CI]: 3.75 [1.57, 8.93], P = .003).

CONCLUSIONS

Pediatric UCT recipients are at a higher risk for ADVd. Antiviral therapy was not associated with an earlier resolution of ADVd, even in patients with higher disease burden.

Management of Adenoviral Keratoconjunctivitis: Challenges and Solutions

Human adenovirus (HAdV) is the most common cause of infectious conjunctivitis, accounting for up to 75% of all conjunctivitis cases and affecting people of all ages and demographics. In addition to ocular complications, it can cause systemic infections in the form of gastroenteritis, respiratory disease, and dissemination in immunocompromised individuals. HAdV causes lytic infection of the mucoepithelial cells of the conjunctiva and cornea, as well as latent infection of lymphoid and adenoid cells. Epidemic keratoconjunctivitis (EKC) is the most severe ocular manifestation of HAdV infection, in which the presence of subepithelial infiltrates (SEIs) in the cornea is a hallmark feature of corneal involvement. SEIs have the tendency to recur and may lead to long-term visual disability. HAdV persistence and dissemination are linked to sporadic outbreaks of adenoviral keratoconjunctivitis. There is no FDA-approved antiviral for treating adenoviral keratoconjunctivitis, and as such, solutions should be proffered to handle the challenges associated with viral persistence and dissemination. Several treatment modalities have been investigated, both systemically and locally, to not only mitigate symptoms but reduce the course of the infection and prevent the risk of long-term complications. These options include systemic and topical antivirals, in-office povidone-iodine irrigation (PVI), immunoglobulin-based therapy, anti-inflammatory therapy, and immunotherapy. More recently, combination PVI/dexamethasone ophthalmic formulations have shown favorable outcomes and were well tolerated in clinical trials for the treatment of EKC. Possible, future treatment considerations include sialic acid analogs, cold atmospheric plasma, N-chlorotaurine, and benzalkonium chloride. Continued investigation and evaluation of treatment are warranted to reduce the economic burden and potential long-term visual debilitation in affected patients. This review will focus on how persistence and dissemination of HAdV pose a significant challenge to the management of adenoviral keratoconjunctivitis. Furthermore, current and future trends in prophylactic and therapeutic modalities for adenoviral keratoconjunctivitis will be discussed.

Brincidofovir: understanding its unique profile and potential role against adenovirus and other viral infections

Brincidofovir (BCV) is a lipid conjugate of cidofovir with good oral bioavailability, enabling optimal intracellular levels of the active drug. Lower rates of nephrotoxicity and myelotoxicity make it a favorable alternative. Despite a greater safety profile among pediatric hematopoietic cell transplant recipients, the oral formulation has been associated with increased gastrointestinal toxicity in adult hematopoietic cell transplant recipients. Oral BCV continues to be developed as a countermeasure against smallpox, while a potentially safer intravenous preparation has been out licensed to another company. BCV has demonstrated great in vitro potency against double-stranded DNA viruses, especially adenovirus. Because of its importance for immunocompromised patients, this review aims to evaluate BCV's clinical and safety profile to support its continued development.