Esther Welkowsky

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 .

BACKGROUND: We analyzed the potential of abiraterone acetate (henceforth abiraterone) to reduce androgen levels below lower limits of quantification (LLOQ) and explored the association with changes in PSA decline in metastatic castration-resistant prostate cancer (mCRPC) patients. METHODS: COU-AA-301 is a 2:1 randomized, double-blind, placebo-controlled study comparing abiraterone (1000 mg q.d.) plus low-dose prednisone (5 mg b.i.d.) with placebo plus prednisone in mCRPC patients post docetaxel. Serum testosterone, androstenedione and dehydroepiandrosterone sulfate from baseline to week 12 were measured by novel ultrasensitive two-dimensional liquid chromatography coupled to tandem mass spectrometry assays in a subset of subjects in each arm (abiraterone plus prednisone, n=80; prednisone, n=38). The association between PSA response (< or =50% baseline) and undetectable androgens (week 12 androgen level below LLOQ) was analyzed using logistic regression. RESULTS: A significantly greater reduction in serum androgens was observed with abiraterone plus prednisone versus prednisone (all P < or = 0.0003), reaching undetectable levels for testosterone (47.2% versus 0%, respectively). A positive association was observed between achieving undetectable serum androgens and PSA decline (testosterone: odds ratio=1.54; 95% confidence interval: 0.546-4.347). Reduction of androgens to undetectable levels did not occur in all patients achieving a PSA response, and a PSA response did not occur in all patients achieving undetectable androgen levels. CONCLUSIONS: Abiraterone plus prednisone significantly reduced serum androgens, as measured by ultrasensitive assays and was generally associated with PSA response. However, androgen decline did not uniformly predict PSA decline suggesting ligand-independent or other mechanisms for mCRPC progression.

Abstract Cellular immunity, mediated by tumor antigen-specific CD4 + and CD8 + T cells, has a critical role in the success of cancer immunotherapy by targeting intracellular driver and passenger tumor mutations. We present the final results of the phase 1 AMPLIFY-201 trial, in which patients who completed standard locoregional treatment, with minimal residual mKRAS disease ( n = 25, 20 pancreatic cancer and 5 colorectal cancer), received monotherapy vaccination with lymph node-targeting ELI-002 2P, including mutant KRAS (mKRAS) amphiphile-peptide antigens (G12D, G12R) and amphiphile-adjuvant CpG-7909. At a median follow-up of 19.7 months, efficacy correlated with mKRAS-specific T cell responses above or below a threshold 9.17-fold increase over baseline, with median radiographic relapse-free survival not reached, versus 3.02 months (hazard ratio (HR) = 0.12, P = 0.0002) and median overall survival not reached versus 15.98 months (HR = 0.23, P = 0.0099). Seventy-one percent of evaluable patients induced both CD4 + and CD8 + subsets, with sustained immunogenicity. Following ELI-002 2P treatment, antigen spreading was observed in 67% of patients, with increased T cells reactive to personalized, tumor antigens absent from the ELI-002 2P vaccine. Therefore, lymph node-targeting amphiphile vaccination induces persistent T cell responses targeting oncogenic driver KRAS mutations, alongside personalized, tumor antigen-specific T cells, which may correlate to clinical outcomes in pancreatic and colorectal cancer. ClinicalTrials.gov registration: NCT04853017 .

TPS2701 Background: Mutations in KRAS and NRAS occur in one quarter of human solid tumors. The G12D allele is the most commonly occurring variant in pancreatic, colorectal, non-small cell lung, ovarian, biliary and gallbladder cancers. ELI-002 2P is an immunotherapeutic comprised of a lymph-node targeted amphiphile (AMP)-modified G12D and G12R mutant KRAS peptides together with an AMP-modified CpG oligonucleotide adjuvant. In preclinical models, ELI-002 demonstrated increased cytotoxic KRAS-specific T cells compared to non-lymph node targeted controls using the same peptide and adjuvant. Clinical evaluation of adoptively transferred KRAS-specific T cells demonstrated objective antitumor activity (Tran 2016). Circulating tumor (ctDNA) methodology permits identification of patients with minimal residual disease (MRD) following locoregional treatment. In MRD setting, immunotherapy is anticipated to succeed as the ratio of effector T cells to target tumor cells is maximized prior to bulk visible disease. The AMPLIFY-201 study (NCT04853017) is evaluating ELI-002 in patients with KRAS mutated solid tumors with MRD. Methods: AMPLIFY-201 is an open-label, dose-escalation and expansion phase I, first in human, trial evaluating ELI-002 2P in patients with KRAS mutated tumors with MRD following standard of care therapy. The initial phase I cohort enrolls patients with colorectal and pancreatic cancer to receive multiple doses of AMP-peptides 70mcg each (1.4 mg total) admixed with AMP-CpG 0.1 mg, administered once every two weeks. Subsequent phase I cohorts will enroll patients with RAS-mutated pancreatic, colorectal, non-small cell lung, ovarian, bile duct or gallbladder cancer, who will receive a fixed dose of AMP-peptides 70 mcg each, together with escalating doses of AMP-CpG. Safety and efficacy will be summarized with descriptive statistics. The maximum tolerated dose (if any) and the recommended phase II dose (RP2D) will be determined with the dose-response activity of ELI-002 2P in eliciting functional KRAS-specific T cells. Preliminary antitumor activity will be characterized using changes from baseline in ctDNA, serum biomarkers appropriate for tumor type, and progression free survival time. Eligibility includes patients who have received standard of care locoregional treatment according to NCCN guidelines and whom have MRD persistence or relapse (ctDNA positive). Patients with colon and pancreas cancer with Stage IV oligometastatic disease (&lt; 3 lesions in one organ) rendered surgically free of disease and with MRD, are also eligible. The dose escalation portion of the study is currently enrolling. Clinical trial information: NCT04853017.

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]