Simplified Admix Archaeal Glycolipid Adjuvanted Vaccine and Checkpoint Inhibitor Therapy Combination Enhances Protection from Murine Melanoma

Abstract

Archaeosomes are liposomes composed of natural or synthetic archaeal lipids that when used as adjuvants induce strong long-lasting humoral and cell-mediated immune responses against entrapped antigens. However, traditional entrapped archaeosome formulations have only low entrapment efficiency, therefore we have developed a novel admixed formulation which offers many advantages, including reduced loss of antigen, consistency of batch-to-batch production as well as providing the option to formulate the vaccine immediately before use, which is beneficial for next generation cancer therapy platforms that include patient specific neo-antigens or for use with antigens that are less stable. Herein, we demonstrate that, when used in combination with anti-CTLA-4 and anti-PD-1 checkpoint therapy, this novel admixed archaeosome formulation, comprised of preformed sulfated lactosyl archaeol (SLA) archaeosomes admixed with OVA antigen (SLA–OVA (adm)), was as effective at inducing strong CD8+ T cell responses and protection from a B16-OVA melanoma tumor challenge as the traditionally formulated archaeosomes with encapsulated OVA protein. Furthermore, archaeosome vaccine formulations combined with anti-CTLA-4 and anti-PD-1 therapy, induced OVA-CD8+ T cells within the tumor and immunohistochemical analysis revealed the presence of CD8+ T cells associated with dying or dead tumor cells as well as within or around tumor blood vessels. Overall, archaeosomes constitute an attractive option for use with combinatorial checkpoint inhibitor cancer therapy platforms.

Adjuvanted Schistosoma mansoni-Cathepsin B With Sulfated Lactosyl Archaeol Archaeosomes or AddaVax™ Provides Protection in a Pre-Clinical Schistosomiasis Model

“…In this work we evaluated the protective capabilities of two new adjuvants: sulfated lactosyl archaeol (SLA) archaeosomes and AddaVax, a squalene-based oil-in-water emulsion similar to MF59. When used as an adjuvant, SLA has been shown to activate strong humoral and cell-mediated responses against multiple antigens by increasing local cytokine production, immune cell trafficking, and antigen uptake at the injection site, leading to increased protection in murine models of infectious disease and cancer (23)(24)(25). In this study, we used a novel admixed formulation which provides a simple ready to mix adjuvant formulation with no loss of antigen during the formulation process (26).…”

Mechanistic insight into the induction of cellular immune responses by encapsulated and admixed archaeosome-based vaccine formulations

“…9 However, we have previously shown with our prime-boost vaccination strategy using a simplified SLA (Adm) formulation that exogenous antigens are similarly capable of inducing robust antigenspecific humoral/cell-mediated responses and tumor immunity as SLA (Enc) in vivo. 7,11 We show in the current study that even a single immunization with SLA (Adm) and (Enc) formulations with normalized lipid content (1,000 µg) can confer similar enhanced protection from B16-OVA melanoma tumor challenge. Whether the similarly enhanced protection conferred by SLA (Adm) and its SLA (Enc) counterpart can be partially attributed to cross-presentation by other specialized DC subsets in vivo remains to be elucidated.…”

“…Archaeosomes are prime adjuvant candidates due to their strong immunostimulatory properties, effective induction of humoral and cell-mediated immunity to numerous antigens and robust ability to confer protective immunity in multiple models of murine infection and cancer. 3,[5][6][7][8][9][10][11] Our novel SLAbased archaeosomes retain the robust adjuvant properties of traditional TPL formulations when antigen is encapsulated, while gaining the key advantage of a simplified semisynthetic single lipid formulation. Recently, we showed that admixing antigen with SLA offers increased consistency of antigen-to-lipid ratios and no antigen loss during formulation relative to antigen encapsulation, with no negative effect on the quality of antigen-specific responses.…”

“…5 We have previously shown that archaeosomes are highly effective adjuvants to numerous antigens, capable of inducing strong humoral and cell-mediated immune responses and protective immunity in multiple models of murine infection and cancer. 3,[5][6][7][8][9][10][11] However, traditional archaeosome formulations were composed of multiple glycolipids making characterization and formulation reproducibility challenging. To simplify formulation, we recently developed an archaeosome comprised of a single glycolipid, sulfated lactosylarchaeol (SLA; 6ʹ-sulfate -β-D-Galp-(1,4)-β-D-Glcp-(1,1)-archaeol), which we have shown can induce strong cellular and humoral responses when used to entrap multiple antigens, such as ovalbumin (OVA), hepatitis B surface antigen (HBsAg), influenza hemagglutinin (HA) and hepatitis C virus (HCV) envelope glycoproteins.…”

The Synergistic Effects of Sulfated Lactosyl Archaeol Archaeosomes When Combined with Different Adjuvants in a Murine Model

“…Archaeosome-based formulations were able to protect immunized mice from multiple pathogens including Listeria monocytogenes , Trypanosoma cruzi and Mycobacterium tuberculosis , as well as to protect against solid and metastatic tumors in murine models [ 11 , 12 , 13 , 14 ]. More recently, we showed that a simplified archaeosome formulation composed of sulfated lactosyl archaeal (SLA) glycolipid can stimulate strong humoral and cell-mediated immune responses to multiple antigens in mice, including those targeting various infectious pathogens (influenza virus, Hepatitis B virus, Hepatitis C virus and Schistomiasis mansoni ) [ 15 , 16 , 17 , 18 ] or tumor types (breast cancer and melanoma) [ 19 , 20 ]. While originally used as delivery vehicles for encapsulated antigen, a simplified SLA formulation where antigens were simply admixed with pre-formed empty SLA vesicles was shown to generate equivalent or superior humoral and cell-mediated immune responses to conventional antigen-entrapped archaeosome formulations [ 21 ].…”