Development of intravenously administered synthetic RNA virus immunotherapy for the treatment of cancer.

The therapeutic effectiveness of oncolytic viruses (OVs) delivered intravenously is limited by the development of neutralizing antibody responses against the virus. To circumvent this limitation and to enable repeated systemic administration of OVs, here we develop Synthetic RNA viruses consisting of a viral RNA genome (vRNA) formulated within lipid nanoparticles. For two Synthetic RNA virus drug candidates, Seneca Valley virus (SVV) and Coxsackievirus A21, we demonstrate vRNA delivery and replication, virus assembly, spread and lysis of tumor cells leading to potent anti-tumor efficacy, even in the presence of OV neutralizing antibodies in the bloodstream. Synthetic-SVV replication in tumors promotes immune cell infiltration, remodeling of the tumor microenvironment, and enhances the activity of anti-PD-1 checkpoint inhibitor. In mouse and non-human primates, Synthetic-SVV is well tolerated reaching exposure well above the requirement for anti-tumor activity. Altogether, the Synthetic RNA virus platform provides an approach that enables repeat intravenous administration of viral immunotherapy.

Optimization of Lipid Nanoparticles for Intramuscular Administration of mRNA Vaccines.

mRNA vaccines have the potential to tackle many unmet medical needs that are unable to be addressed with conventional vaccine technologies. A potent and well-tolerated delivery technology is integral to fully realizing the potential of mRNA vaccines. Pre-clinical and clinical studies have demonstrated that mRNA delivered intramuscularly (IM) with first-generation lipid nanoparticles (LNPs) generates robust immune responses. Despite progress made over the past several years, there remains significant opportunity for improvement, as the most advanced LNPs were designed for intravenous (IV) delivery of siRNA to the liver. Here, we screened a panel of proprietary biodegradable ionizable lipids for both expression and immunogenicity in a rodent model when administered IM. A subset of compounds was selected and further evaluated for tolerability, immunogenicity, and expression in rodents and non-human primates (NHPs). A lead formulation was identified that yielded a robust immune response with improved tolerability. More importantly for vaccines, increased innate immune stimulation driven by LNPs does not equate to increased immunogenicity, illustrating that mRNA vaccine tolerability can be improved without affecting potency.

Multi-antigenic human cytomegalovirus mRNA vaccines that elicit potent humoral and cell-mediated immunity.

A cytomegalovirus (CMV) vaccine that is effective at preventing congenital infection and reducing CMV disease in transplant patients remains a high priority as no approved vaccines exist. While the precise correlates of protection are unknown, neutralizing antibodies and antigen-specific T cells have been implicated in controlling infection. We demonstrate that the immunization of mice and nonhuman primates (NHPs) with lipid nanoparticles (LNP) encapsulating modified mRNA encoding CMV glycoproteins gB and pentameric complex (PC) elicit potent and durable neutralizing antibody titers. Since the protective correlates in pregnant women and transplant recipients may differ, we developed an additional mRNA vaccine expressing the immunodominant CMV T cell antigen pp65. Administration of pp65 vaccine with PC and gB elicited robust multi-antigenic T cell responses in mice. Our data demonstrate that mRNA/LNP is a versatile platform that enables the development of vaccination strategies that could prevent CMV infection and consequent disease in different target populations.