Lochana M. Seenappa

Abstract Pancreatic and colorectal cancers are often KRAS mutated and are incurable when tumor DNA or protein persists or recurs after curative intent therapy. Cancer vaccine ELI-002 2P enhances lymph node delivery and immune response using amphiphile (Amph) modification of G12D and G12R mutant KRAS (mKRAS) peptides (Amph-Peptides-2P) together with CpG oligonucleotide adjuvant (Amph-CpG-7909). We treated 25 patients (20 pancreatic and five colorectal) who were positive for minimal residual mKRAS disease (ctDNA and/or serum tumor antigen) after locoregional treatment in a phase 1 study of fixed-dose Amph-Peptides-2P and ascending-dose Amph-CpG-7909; study enrollment is complete with patient follow-up ongoing. Primary endpoints included safety and recommended phase 2 dose (RP2D). The secondary endpoint was tumor biomarker response (longitudinal ctDNA or tumor antigen), with exploratory endpoints including immunogenicity and relapse-free survival (RFS). No dose-limiting toxicities were observed, and the RP2D was 10.0 mg of Amph-CpG-7909. Direct ex vivo mKRAS-specific T cell responses were observed in 21 of 25 patients (84%; 59% both CD4 + and CD8 + ); tumor biomarker responses were observed in 21 of 25 patients (84%); biomarker clearance was observed in six of 25 patients (24%; three pancreatic and three colorectal); and the median RFS was 16.33 months. Efficacy correlated with T cell responses above or below the median fold increase over baseline (12.75-fold): median tumor biomarker reduction was −76.0% versus −10.2% ( P < 0.0014), and the median RFS was not reached versus 4.01 months (hazard ratio = 0.14; P = 0.0167). ELI-002 2P was safe and induced considerable T cell responses in patients with immunotherapy-recalcitrant KRAS-mutated tumors. ClinicalTrials.gov identifier: NCT04853017 .

Abstract The recent emergence of a causal link between Epstein-Barr virus (EBV) and multiple sclerosis has generated considerable interest in the development of an effective vaccine against EBV. Here we describe a vaccine formulation based on a lymph node targeting Amphiphile vaccine adjuvant, Amphiphile-CpG, admixed with EBV gp350 glycoprotein and an engineered EBV polyepitope protein that includes 20 CD8 + T cell epitopes from EBV latent and lytic antigens. Potent gp350-specific IgG responses are induced in mice with titers >100,000 in Amphiphile-CpG vaccinated mice. Immunization including Amphiphile-CpG also induces high frequencies of polyfunctional gp350-specific CD4 + T cells and EBV-specific CD8 + T cells that are 2-fold greater than soluble CpG and are maintained for >7 months post immunization. This combination of broad humoral and cellular immunity against multiple viral determinants is likely to provide better protection against primary infection and control of latently infected B cells leading to protection against the development of EBV-associated diseases.

1 isotypes (IgG2c and IgG3) and potently neutralized Spike-2-ACE2 receptor binding, with titers 265-fold higher than natural convalescent patient COVID-19 responses; T cell and antibody responses were maintained despite 10-fold dose reduction in Spike antigen. Both cellular and humoral immune responses were preserved in aged mice. These advantages merit clinical translation to SARS-CoV-2 and other protein subunit vaccines.

2528 Background: RAS mutations occur in 25% of solid tumors with G12D being the most frequent variant. ELI-002 2P is a vaccine comprised of lymph-node targeted Amphiphile (Amph)-modified G12D and G12R mutant KRAS peptides with an Amph-modified CpG oligonucleotide adjuvant designed to expand polyfunctional mutant KRAS-specific T cells. Preclinical amphiphile data (relative to non-amphiphile controls) showed increased immunogenicity, tumor clearance and survival in mouse models. Methods: This first-in-human multicenter phase I trial assessed safety, immunogenicity and antitumor activity using a novel adjuvant trial design in patients (pts) with minimal residual disease (MRD) following standard locoregional treatment. Eligibility: elevated circulating tumor DNA (ctDNA) and/or serum tumor biomarker elevation (CA19-9/CEA), and KRAS/NRAS mutation. In a 3+3 dose escalation, n=22 received a subcutaneous course of 6 prime and 4 booster injections of fixed dose Amph-peptides (1.4 mg), admixed with escalating Amph-CpG-7909 (Table). Dose escalation based on observed safety in first 28 days. Safety, antitumor activity including biomarker reduction/clearance and relapse free survival using immune Response Evaluation Criteria in Solid Tumors (iRECIST) were assessed. Immunogenicity assessed by direct ex vivo Fluorospot and intracellular cytokine staining of peripheral blood mononuclear cells (T-cell responders = ≥ 2-fold increase over baseline) and by tumor CD3 immunohistochemistry in subset who underwent a biopsy. Results: No dose-limiting toxicities, treatment related SAEs or cytokine release syndrome were observed, and no maximum tolerated dose was identified. Safety: all grade 1, fatigue (19%), headache (19%), and injection site reaction (9.5%). Biomarker reduction was observed in 15/19 (79%) and in 5/5 at highest doses; clearance of MRD was observed in 4/19 (21% - n=2 pancreas, n=2 colorectal). Polyfunctional mKRAS-specific T cell responses observed in 80% of pts (n=12/15), with both CD8+ and CD4+ T cell responses for most, and CD3+ T cells observed on biopsies. The recommended phase 2 dose (RP2D) is 10.0 mg Amph-CpG-7909. Conclusions: ELI-002 2P, evaluated in a novel MRD+ trial, was safe with ctDNA and serum tumor biomarker reduction and clearance and notable immune responses. The RP2D is the start dose for a phase 1/randomized phase 2 study evaluating a new seven peptide formulation for G12 D, R, V, S, A, C, and G13D mutated solid tumors (NCT05726864). Clinical trial information: NCT04853017 . [Table: see text]

Despite the success of currently authorized vaccines for the reduction of severe COVID-19 disease risk, rapidly emerging viral variants continue to drive pandemic waves of infection, resulting in numerous global public health challenges. Progress will depend on future advances in prophylactic vaccine activity, including advancement of candidates capable of generating more potent induction of cross-reactive T cells and durable cross-reactive antibody responses. Here we evaluated an Amphiphile (AMP) adjuvant, AMP-CpG, admixed with SARS-CoV-2 Spike receptor binding domain (RBD) immunogen, as a lymph node-targeted protein subunit vaccine (ELI-005) in mice and non-human primates (NHPs). AMP-mediated targeting of CpG DNA to draining lymph nodes resulted in comprehensive local immune activation characterized by extensive transcriptional reprogramming, inflammatory proteomic milieu, and activation of innate immune cells as key orchestrators of antigen-directed adaptive immunity. Prime-boost immunization with AMP-CpG in mice induced potent and durable T cell responses in multiple anatomical sites critical for prophylactic efficacy and prevention of severe disease. Long-lived memory responses were rapidly expanded upon re-exposure to antigen. In parallel, RBD-specific antibodies were long-lived, and exhibited cross-reactive recognition of variant RBD. AMP-CpG-adjuvanted prime-boost immunization in NHPs was safe and well tolerated, while promoting multi-cytokine-producing circulating T cell responses cross-reactive across variants of concern (VOC). Expansion of RBD-specific germinal center (GC) B cells in lymph nodes correlated to rapid seroconversion with variant-specific neutralizing antibody responses exceeding those measured in convalescent human plasma. These results demonstrate the promise of lymph-node adjuvant-targeting to coordinate innate immunity and generate robust adaptive responses critical for vaccine efficacy.