A plant-expressed conjugate vaccine breaks CD4⁺ tolerance and induces potent immunity against metastatic Her2⁺ breast cancer

Abstract

Passive antibody therapy for cancer is an effective but costly treatment modality. Induction of therapeutically potent anticancer antibodies by active vaccination is an attractive alternative but has proven challenging in cancer due to tolerogenic pressure in patients. Here, we used the clinically relevant cancer target Her2, known to be susceptible to targeting by antibody therapy, to demonstrate how potent antibody can be induced by vaccination. A novel 44kD Her2 protein fragment was generated and found to be highly effective at inducing anti-Her2 antibody including trastuzumab-like reactivities. In the tolerant and spontaneous BALB-neuT mouse model of metastatic breast cancer this Her2-targeting vaccine was only effective if the fragment was conjugated to a foreign immunogenic carrier; Fragment C of tetanus toxin. Only the conjugate vaccine induced high affinity anti-Her2 antibody of multiple isotypes and suppressed tumor development. The magnitude of CD4+ T-cell help and breadth of cytokines secreted by the CD4+ T helper (Th) cells induced to the foreign antigen was critical. We used a highly efficient plant-based bio-manufacturing process for protein antigens, magnICON, for vaccine expression, to underpin feasibility of future clinical testing. Hence, our novel Her2-targeting conjugate vaccine combines preclinical efficacy with clinical deliverability, thus setting the scene for therapeutic testing.

NOX4 Inhibition Potentiates Immunotherapy by Overcoming Cancer-Associated Fibroblast-Mediated CD8 T-cell Exclusion from Tumors

“…4T1 cancer cells (0.25  10 5 ) in PBS were injected s.c. into the upper mammary fat pad of female mice ages 8 to 10 weeks. Cells were either injected alone or mixed with 1.25  10 5 BALB/c breast CAF isolated from transgenic BALB-neuT spontaneous breast tumors (25). Tumors were measured every 2 to 3 days by electronic skin caliper from longest width and length, and tumor volume was calculated using the formula 4/3p  r 3 , where the radius (r) was calculated from tumor width and length measurement to provide an average diameter value.…”

“…Each module was then summarized by the first principal component gene (module eigengene, ME; representing a suitably defined average of the gene module). GO Biological processes and Kyoto Encyclopedia of Genes and Genomes Pathway enrichment analyses were carried using GSEA where all genes were ranked by their correlation to the module eigengene using the fgsea package in R (25).…”

Linear doggybone DNA vaccine induces similar immunological responses to conventional plasmid DNA independently of immune recognition by TLR9 in a pre-clinical model

“…Although antibody responses are not directly involved in protection against the TC-1 tumour there is scope for antibody to have an effect on antigen presentation via immune complexes and hence induction of CD8 T cells [ 26 ]. Additionally for targets located on the cell surface induced antibody can provide an effective way of targeting cancer cells [ 19 , 27 ]. We therefore, measured total levels of anti-E7 or anti-E6 IgG in individual mice primed and boosted with either the DB or PL vaccines with or without EP.…”

“…E7 protein was purified using glutathione beads (GE Healthcare) following the manufacturer’s protocol. Serum antibody bound to the coated antigen was detected with HRP-conjugated anti-mouse IgG (The Binding Site), anti-IgG1 (Oxford Biotechnology), anti-IgG2b or anti-IgG2c (both from Harlan Sera-Lab) as previously [ 16 , 19 ].…”

Reconceptualizing Cancer Immunotherapy Based on Plant Production Systems

“…This Her2-targeting vaccine required conjugation to a foreign immunogenic carrier, fragment C of tetanus toxin, to be effective. The vaccine was proven to be successful in a mouse model [ 56 ]. Alternatively, Esfandiari et al .…”