Respiratory viral infections in the immunocompromised

NPP-669, a prodrug of cidofovir, is highly efficacious against human adenovirus infection in the permissive Syrian hamster model

Human adenoviruses can cause serious, disseminated infections in immunocompromised patients. For pediatric allogeneic stem cell transplant patients, the case fatality rate can reach 80%. Still, there is no available antiviral drug that is specifically approved by the Food and Drug Administration for the treatment of adenovirus infections. To fill this pressing medical need, we have developed NPP-669, a prodrug of cidofovir with broad activity against double-stranded DNA viruses, including adenoviruses. Here, we report on the in vivo anti-adenoviral efficacy of NPP-669. Using the immunosuppressed Syrian hamster as the model, we show that NPP-669 is highly efficacious when dosed orally at 1 mg/kg and 3 mg/kg. In a delayed administration experiment, NPP-669 was more effective than brincidofovir, a similar compound that reached Phase III clinical trials. Furthermore, parenteral administration of NPP-669 increased its efficacy approximately 10-fold compared to oral dosing without apparent toxicity, suggesting that this route may be preferable in a hospital setting. Based on these findings, we believe that NPP-669 is a promising new compound that needs to be further investigated.

Respiratory Viral Infections in Recipients of Cellular Therapies: A Review of Incidence, Outcomes, Treatment, and Prevention

Respiratory viral infections (RVIs) are of major clinical importance in immunocompromised patients and represent a substantial cause of morbidity and mortality in patients with hematologic malignancies and those who have undergone hematopoietic cell transplantation. Similarly, patients receiving immunotherapy with CD19-targeted chimeric antigen receptor-modified T cells, natural killer cells, and genetically modified T-cell receptors are susceptible to RVIs and progression to lower respiratory tract infections. In adoptive cellular therapy recipients, this enhanced susceptibility to RVIs results from previous chemotherapy regimens such as lymphocyte-depleting chemotherapy conditioning regimens, underlying B-cell malignancies, immune-related toxicities, and secondary prolonged, profound hypogammaglobulinemia. The aggregated risk factors for RVIs have both immediate and long-term consequences. This review summarizes the current literature on the pathogenesis, epidemiology, and clinical aspects of RVIs that are unique to recipients of adoptive cellular therapy, the preventive and therapeutic options for common RVIs, and appropriate infection control and preventive strategies.