Cancer immunotherapy with enveloped self-amplifying mRNA CARG-2020 that modulates IL-12, IL-17 and PD-L1 pathways to prevent tumor recurrence

Targeting multiple immune mechanisms may overcome therapy resistance and further improve cancer immunotherapy for humans. Here, we describe the application of virus-like vesicles (VLV) for delivery of three immunomodulators alone and in combination, as a promising approach for cancer immunotherapy. VLV vectors were designed to deliver single chain interleukin (IL)-12, short-hairpin RNA (shRNA) targeting programmed death ligand 1 (PD-L1), and a dominant-negative form of IL-17 receptor A (dn-IL17RA) as a single payload or as a combination payload. Intralesional delivery of the VLV vector expressing IL-12 alone, as well as the trivalent vector (designated CARG-2020) eradicated large established tumors. However, only CARG-2020 prevented tumor recurrence and provided long-term survival benefit to the tumor-bearing mice, indicating a benefit of the combined immunomodulation. The abscopal effects of CARG-2020 on the non-injected contralateral tumors, as well as protection from the tumor cell re-challenge, suggest immune-mediated mechanism of protection and establishment of immunological memory. Mechanistically, CARG-2020 potently activates Th1 immune mechanisms and inhibits expression of genes related to T cell exhaustion and cancer-promoting inflammation. The ability of CARG-2020 to prevent tumor recurrence and to provide survival benefit makes it a promising candidate for its development for human cancer immunotherapy.

Antigenic requirement for Gag in a vaccine that protects against high-dose mucosal challenge with simian immunodeficiency virus

We reported previously on a vaccine approach that conferred apparent sterilizing immunity to SIVsmE660. The vaccine regimen employed a prime-boost using vectors based on recombinant vesicular stomatitis virus (VSV) and an alphavirus replicon expressing either SIV Gag or SIV Env. In the current study, we tested the ability of vectors expressing only the SIVsmE660 Env protein to protect macaques against the same high-dose mucosal challenge. Animals developed neutralizing antibody levels comparable to or greater than seen in the previous vaccine study. When the vaccinated animals were challenged with the same high-dose of SIVsmE660, all became infected. While average peak viral loads in animals were slightly lower than those of previous controls, the viral set points were not significantly different. These data indicate that Gag, or the combination of Gag and Env are required for the generation of apparent sterilizing immunity to the SIVsmE660 challenge.