Effect of CpG methylation on isotype and magnitude of antibody responses to influenza hemagglutinin-expressing plasmid

We previously showed that intramuscular saline DNA immunizations favor the development of an IgG2a-dominant Th1 immune response, whereas gene gun DNA immunizations stimulate the production of an IgG1-dominant Th2 immune response. Several studies have implicated immunostimulatory CpG sequences as the causative factor in the development of Th1 immune responses to saline DNA immunization. To determine whether the Th1 cytokine-inducing properties of CpG sequences in plasmid DNA (pDNA) were responsible for the induction of a Th1 immune response, in vitro methylated and untreated (nonmethylated) hemagglutinin-expressing pDNA were compared for immunogenicity. Methylation abrogated the immunostimulatory activity of pDNA for cultured splenocytes and significantly reduced antigen expression. However, methylation of pDNA was not associated with a change from the induction of IgG2a to IgG1. After immunization with the methylated plasmid, the magnitude of the immune response was reduced. However, the decline in the total antibody response matched the decline in antigen expression. The dose of DNA or the presence of lipopolysaccharide in pDNA likewise did not affect the preferential development of an IgG2a antibody response. Our findings reveal that high levels of CpG sequences are not required for raising IgG2a-predominant, Thl-biased immune responses to intramuscular injections of hemagglutinin-expressing DNA

Different T helper cell types and antibody isotypes generated by saline and gene gun DNA immunization

Several routes and methods of DNA immunization have been shown to generate Ab, Th cells, and CTL responses. However, few studies have directly compared the immune responses generated by different routes and methods of DNA immunization. Utilizing an influenza hemagglutinin (H1)-expressing plasmid, we compared the immune response produced by saline injection of DNA into skin or muscle, and gene gun immunization of skin or muscle. We found that saline-DNA immunization raised a predominantly Th1 response with mostly IgG2a anti-H1 Ab, while gene gun DNA immunization produced a predominantly Th2 response with mostly IgG1 anti-H1 Abs. These distinct types of immune responses were generated by the method, not the route, of DNA immunization. The initial immunization established the Th cell-type of the immune response. The Th cell-type did not change with further DNA immunizations by the same or the alternate method, or after a viral challenge. The ability to generate different Th types was not due to differences in the doses of DNA used in saline and gene gun DNA immunization. These findings have important implications for vaccine design and studies of the mechanism of Th cell differentiation

DNA immunization for influenza virus: studies using hemagglutinin- and nucleoprotein-expressing DNAs

DNA-based immunizations have been used to analyze the ability of DNA-expressed hemagglutinin (HA) and nucleoprotein (NP) to protect BALB/c mice against a homologous influenza virus, A/PR/8/34 (H1N1), challenge. The HA DNA, but not the NP DNA, protected mice against the lethal viral challenge. For the HA DNA, single gene gun inoculations of 0.04 microg and boosted inoculations of 0.004 microg of DNA raised complete protection. For the NP DNA, boosted gene gun immunizations of 0.4 microg of DNA and boosted intradermal or intramuscular injections of 50 microg of DNA failed to protect. The protection elicited by the HA DNA vaccine correlated with the titers of neutralizing antibody

Society for Immunotherapy of Cancer (SITC) consensus definitions for resistance to combinations of immune checkpoint inhibitors with targeted therapies

Immunotherapy offers deep and durable disease control to some patients, but many tumors do not respond to treatment with single-agent immune checkpoint inhibitors (ICIs). One strategy to enhance responses to immunotherapy is via combinations with signal transduction inhibitors, such as antiangiogenic therapies, which not only directly target cancer cells but also could potentially favorably modulate the tumor immune microenvironment. Combination strategies with ICIs have demonstrated enhanced antitumor activity compared with tumor-targeted or antiangiogenic therapy alone in randomized trials in a variety of solid tumor settings, leading to regulatory approval from the US Food and Drug Administration and agencies in other countries for the treatment of endometrial cancer, kidney cancer, melanoma, and hepatocellular carcinoma. Despite improved survival and response rates for some patients when antiangiogenic or targeted therapies are administered with ICIs, many patients continue to progress after combination treatment and urgently need new strategies to address this manifestation of resistance to immunotherapy. Previously, the Society for Immunotherapy of Cancer (SITC) published consensus definitions for resistance to single-agent anti-PD-(L)1. To provide guidance for clinical trial design and to support analyses of emerging molecular and immune profiling data surrounding mechanisms of resistance to ICI-based combinations, SITC convened a follow-up workshop in 2021 to develop consensus definitions for resistance to multiagent ICI combinations. This manuscript reports the consensus clinical definitions for combinations of anti-PD-(L)1 ICIs and targeted therapies. Definitions for resistance to ICIs in combination with chemotherapy and with other ICIs will be published in companion volumes to this paper

Society for Immunotherapy of Cancer (SITC) consensus definitions for immune checkpoint inhibitor-associated immune-related adverse events (irAEs) terminology

Immune-related adverse events (irAEs) associated with immune checkpoint inhibitor (ICI) therapy may vary substantially in their clinical presentation, including natural history, outcomes to treatment, and patterns. The application of clinical guidelines for irAE management can be challenging for practitioners due to a lack of common or consistently applied terminology. Furthermore, given the growing body of clinical experience and published data on irAEs, there is a greater appreciation for the heterogeneous natural histories, responses to treatment, and patterns of these toxicities, which is not currently reflected in irAE guidelines. Furthermore, there are no prospective trial data to inform the management of the distinct presentations of irAEs. Recognizing a need for uniform terminology for the natural history, response to treatment, and patterns of irAEs, the Society for Immunotherapy of Cancer (SITC) convened a consensus panel composed of leading international experts from academic medicine, industry, and regulatory agencies. Using a modified Delphi consensus process, the expert panel developed clinical definitions for irAE terminology used in the literature, encompassing terms related to irAE natural history (ie, re-emergent, chronic active, chronic inactive, delayed/late onset), response to treatment (ie, steroid unresponsive, steroid dependent), and patterns (ie, multisystem irAEs). SITC developed these definitions to support the adoption of a standardized vocabulary for irAEs, which will have implications for the uniform application of irAE clinical practice guidelines and to enable future irAE clinical trials