Brincidofovir as Salvage Therapy for Adenovirus Disease in Intestinal Transplant Recipients

Respiratory Viruses in Solid Organ Transplant Recipients

Solid organ transplantation is often lifesaving, but does carry an increased risk of infection. Respiratory viral infections are one of the most prevalent infections, and are a cause of significant morbidity and mortality, especially among lung transplant recipients. There is also data to suggest an association with acute rejection and chronic lung allograft dysfunction in lung transplant recipients. Respiratory viral infections can appear at any time post-transplant and are usually acquired in the community. All respiratory viral infections share similar clinical manifestations and are all currently diagnosed using nucleic acid testing. Influenza has good treatment options and prevention strategies, although these are hampered by resistance to neuraminidase inhibitors and lower vaccine immunogenicity in the transplant population. Other respiratory viruses, unfortunately, have limited treatments and preventive methods. This review summarizes the epidemiology, clinical manifestations, therapies and preventive measures for clinically significant RNA and DNA respiratory viruses, with the exception of SARS-CoV-2. This area is fast evolving and hopefully the coming decades will bring us new antivirals, immunologic treatments and vaccines.

Filociclovir Is a Potent In Vitro and In Vivo Inhibitor of Human Adenoviruses

Human adenovirus (HAdV) infection is common in the general population and can cause a range of clinical manifestations, among which pneumonia and keratoconjunctivitis are the most common. Although HAdV infections are mostly self-limiting, infections in immunocompromised individuals can be severe. No antiviral drug has been approved for treating adenoviruses. Filociclovir (FCV) is a nucleoside analogue which has successfully completed phase I human clinical safety studies and is now being developed for treatment of human cytomegalovirus (HCMV)-related disease in immunocompromised patients. In this report, we show that FCV is a potent broad-spectrum inhibitor of HAdV types 4 to 8, with 50% effective concentrations (EC50s) ranging between 1.24 and 3.6 μM and a 50% cytotoxic concentration (CC50) of 100 to 150 μM in human foreskin fibroblasts (HFFs). We also show that the prophylactic oral administration of FCV (10 mg/kg of body weight) 1 day prior to virus challenge and then daily for 14 days to immunosuppressed Syrian hamsters infected intravenously with HAdV6 was sufficient to prevent morbidity and mortality. FCV also mitigated tissue damage and inhibited virus replication in the liver. The 10-mg/kg dose had similar effects even when the treatment was started on day 4 after virus challenge. Furthermore, FCV administered at the same dose after intranasal challenge with HAdV6 partially mitigated body weight loss but significantly reduced pathology and virus replication in the lung. These findings suggest that FCV could potentially be developed as a pan-adenoviral inhibitor.

Adenovirus diseases: a systematic review and meta-analysis of 228 case reports

OBJECTIVE

The clinical characteristics of various adenovirus (ADV) infection are underexplored up till now. To investigate the risk factors, manifestation, current status of ADV species, treatment and prognosis of this disease.

METHODS

We performed a Pubmed and Embase systematic review for case report reporting the ADV infection to analyze the clinical characteristics of disease.

RESULTS

Initial database searched identified articles of which 168 (228 cases) were included in the final analysis. Previous solid organ transplantation [odds ratio (OR) = 3.45, 95% CI 1.31-9.08, P = 0.01], hematopoietic stem cell transplant (OR = 4.24, 95% CI 1.33-13.51, P = 0.01) and hematological malignancy (OR = 4.78, 95% CI 1.70-13.46, P = 0.01) were associated with increased risk of disseminated ADV infection. Use of corticosteroids (OR = 3.86, 95% CI 1.21-12.24, P = 0.02) was a significant risk factor for acquiring urinary tract infections. A total of six species (21 types) of ADV infection have been identified in 100/228 (43.9%) cases. ADV B was the most common species. ADV B species (26/60, 52.0% or 5/41, 12.2% P = 0.001) were more isolated in patients with ADV pneumonia. ADV C (13/15, 86.7% versus 35/86, 40.7% P = 0.001) species were more identified in patients with disseminated disease. The species associated with keratoconjunctivitis is only ADV D in our analysis. Urinary tract ADV infections were observed in ADV A/B/D species. Cidofovir (CDV) (82/228, 36.0%) remained the most commonly antiviral therapy in our cases, followed by ribavirin (15/228, 6.6%), ganciclovir (18/228, 7.9%), and brincidofovir (12/228, 5.3%). Brincidofovir was administered as salvage therapy in 10 cases. Death was reported in 81/228 (35.5%) patients. Mortality rate was higher among patients with gastrointestinal (GI) ADV infection (5/10, 50.0%), ADV pneumonia (20/45, 44.4%) and disseminated ADV infection (53/122, 43.4%).

CONCLUSION

Previous solid organ transplantation, hematopoietic stem cell transplant and hematological malignancy were risk factors for disseminated ADV infection. Use of corticosteroids was significant for urinary tract ADV infection. Different species correlated with different clinical manifestations of infection. Mortality rate was higher among patients with GI disease, pneumonia and disseminated disease. Our review clarified the current treatment of ADV infections, and more treatment required further investigation.

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.

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

Adenovirus infection is a well-known complication in patients receiving hematopoietic stem cell transplantation (HSCT). Brincidofovir (BCV) is an orally bioavailable lipid conjugate of cidofovir, which has activity against adenoviruses. We present a review of adenovirus infections treated with BCV which were unresponsive to cidofovir initially in 4 patients and it was used upfront in one patient. Children with adenovirus infection following HSCT treated with BCV, between July 2014 and February 2018 were recognized. Five patients including 3 male and 2 female with a median age of 10 years (range, 2.2 to 10 y) were identified. The median days of adenoviremia detection was 18 days (range, 7 to 303 d) posttransplant. The median peak viral load by quantitative polymerase chain reaction was 21,38,000 copies/mL (range, 1,77,200 to 31,97,000 copies/mL). The median time from first detection of adenoviremia to become negative was 30 days (range, 15 to 113 d). The sites involved were gastrointestinal tract in all patients and 2 patients had additional respiratory tract involvement. Two patients survived and 3 patients died of sepsis. All patients responded well to BCV and no adverse effect was noticed. We saw the good safety profile and excellent antiadenoviral activity of BCV in pediatric patients receiving HSCT without the nephrotoxicity and it may have a role in preemptive therapy.

Brincidofovir (CMX001) for the Treatment of Severe Adenoviral Pneumonia in Kidney Transplant Recipient

Adenovirus causes significant morbidity and mortality in solid organ and hematological transplant recipients. Treatment of adenovirus infections includes supportive care, reduction of immune suppression, and in patients with severe disease, intravenous cidofovir. Brincidofovir (CMX001) is a lipid conjugate of cidofovir, with good oral bioavailability, no associated nephrotoxicity, and higher intracellular levels of the active drug compared to cidofovir. We describe a case of severe adenoviral pneumonia in an adult renal transplant recipient who was successfully treated with oral brincidofovir after developing renal insufficiency with intravenous cidofovir. Brincidofovir (CMX001) along with other supportive therapy, may offer an efficacious, safe, and well-tolerated treatment for severe adenoviral infections in solid organ transplant recipients.

Characterization of T cell immunophenotypes in intestinal transplantation: A pilot study

Immunophenotyping of peripheral blood mononuclear cells has been shown to be a useful, non-invasive method of predicting acute cellular rejection (ACR) following intestinal transplantation (ITx). Our objectives were to characterize differences in the T cell immunophenotype of ITx recipients in peripheral blood samples (1) collected late versus early after ITx and (1) associated with episodes of ACR and infectious enteritis. An IRB-approved, cross-sectional study of ITx recipients was performed. Peripheral blood samples were collected during normal visits and episodes of allograft dysfunction. A total of 38 patients were included in the analysis: 31 ITx recipients (87% liver-inclusive allografts) and 7 intestinal failure control patients. Of the ITx patients, 26 patients were pediatric patients (<21 years). A total of 70 samples were analyzed from ITx recipients, including 51 during normal visits and 19 during episodes of allograft dysfunction (median of 2 samples per patient; range of 1-6 samples per patient). In the late (n = 32) versus early post-ITx (n = 19) normal samples, there was a significantly higher percentage of central memory CD4 T cells (p = .001). In the ACR (n = 5) versus infectious enteritis (n = 14) samples, there was a higher percentage of CD8 T cells expressing HLA-DR (p = .002), CD57 (p < .001), and KLRG1 (p < .001) and a higher percentage of CD4 T cells expressing CD57 (p = .03). Additional studies are needed with larger cohorts to validate these changes in the T cell immunophenotype. Further elucidating T cell immunophenotypes in ITx will lead to a better understanding of immune mechanisms of allograft dysfunction, identification of potential biomarkers in ITx, and optimized selection of immunosuppressive therapies.