According to the companies reported, ASP0113 (Astellas Pharma Inc./Vical Incorporated), an investigational DNA vaccine being developed for cytomegalovirus (CMV)- seropositive hematopoietic stem cell transplant recipients, did not significantly enhance overall mortality and CMV end-organ disease through the first year following the transplant.
ASP0113 failed to meet its primary or secondary endpoints in the phase 3 HELIOS clinical trial, which was intended to assess the vaccine’s efficacy compared with placebo in CMV-seropositive recipients undergoing an allogeneic stem cell transplant.
Efficacy was evaluated using a primary composite endpoint of overall mortality and CMV end-organ disease through the first year following the transplant, an endpoint which was not met.
Secondary endpoints of time to the first protocol defined CMV viremia and time to first use of adjudicated CMV-particular antiviral treatment also were not met.
Both companies expressed disappointment with the outcomes in what Vijay Samant, Vical’s Chief Executive Officer, described as a “very difficult-to-treat patient populace.”
The companies have not release accurate efficacy results. The vaccine was well tolerated; being the most commonly detailed adverse event is reactions at the injection site.
The phase 3 trial was a 1:1 randomized, double-blind, placebo-controlled study that enlisted 514 CMV seropositive subjects undergoing hematopoietic stem cell transplantation.
Randomization was stratified by donor CMV serostatus and donor-recipient relatedness. Subjects were taken after for one-year post-transplant.
CMV is a herpes virus that is assessed to infect more than half of all adults in the United States by age 50 and is significantly more widespread in developing countries.
A healthy immune system typically protects an infected individual against CMV disease but does not prevent or latent infection.
Immune systems of individuals are not fully functional, are at high risk of CMV reactivation and potentially leading to severe illness or death.
Those at most serious risk include HCT and solid-organ transplant recipients, and additionally infants born to mothers who initially become infected during pregnancy.
ASP0113 is an investigational vaccine candidate intended to prevent CMV disease and associated complications in CMV-seropositive HCT recipients.
ASP0113 is a bivalent DNA vaccine encoding CMV phosphoprotein 65 and glycoprotein B antigens for induction of both cellular and humoral immune responses, formulated with a proprietary poloxamer-based delivery system.
ASP0113 was at first created by Vical, which partnered with Astellas for further improvement and commercialization. ASP0113 received orphan drug designation in the United States and Europe.