On June 4, 2021 Genocea Biosciences, Inc. (NASDAQ: GNCA), a biopharmaceutical company developing next-generation neoantigen immunotherapies, reported that updated immunogenicity and clinical response data from the GEN-009 Phase 1 trial that continue to validate the company’s unique and differentiated approach to identifying clinically meaningful immunotherapy targets through the proprietary ATLAS selection process (Press release, Genocea Biosciences, JUN 4, 2021, View Source [SID1234583551]). Data on the neoantigen vaccine combined with PD-1 inhibition in advanced solid tumors will be shared by Maura Gillison, M.D., Ph.D., Lead Investigator, MD Anderson Cancer Center, during a poster presentation (Abstract #2613) at the virtual 2021 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting from June 4-8, 2021. The poster is available for on-demand viewing on the ASCO (Free ASCO Whitepaper) website and also posted to the Scientific Resources section of the Genocea website at View Source
Long-term results demonstrate that GEN-009 continues to generate broad immune responses against neoantigens that can lead to sustained clinical responses. In Part A of the study, designed to measure safety and immunogenicity only, eight patients with no measurable disease were vaccinated with GEN-009 as a monotherapy. Six of the eight patients continue without recurrence with a median follow up of 25 months post start of the vaccination. Notably, as previously reported, GEN-009 elicited T cell immune responses to 99% of the ATLAS-selected neoantigens, the highest seen across neoantigen vaccine programs.
In Part B, patients were enrolled at the initiation of a PD-1 checkpoint inhibitor (CPI)-based standard of care (SOC) regimen for advanced or metastatic disease; patients who were controlled on SOC and did not require alternate therapy are labeled CPI-sensitive, patients who required alternate therapy before vaccination are labeled CPI-refractory. Of the nine CPI-sensitive patients, the latest data show four patients experienced novel reduction in tumor volume post-GEN-009 dosing and achieved independent RECIST responses after vaccination, including three partial responses (PRs) and one complete response (CR). This is an increase from the two PRs and one CR previously reported at SITC (Free SITC Whitepaper) 2020. The remaining five CPI-sensitive patients all achieved disease stabilization. Across the CPI-sensitive cohort, the median duration without disease progression after initial GEN-009 vaccination was 15 months. Of the seven CPI-refractory patients, two achieved stable disease after initial GEN-009 vaccination for up to 10 months. GEN-009 has been well tolerated with only mild adverse events associated with the vaccine adjuvant.

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Expanded immunogenicity data from Part B of the study revealed that vaccine-specific T cell responses were detected ex vivo after the first dose of the vaccine and continued to rise with each subsequent dose. Vaccine-specific T cell responses remained significantly elevated over baseline and post-CPI, pre-vaccine timepoints for at least 6 months, showing persistence of the vaccine response. CPI-sensitive subjects had a greater number of neoantigens identified with ATLAS at baseline compared with patients in the CPI-refractory cohort, and also had evidence of epitope spread for CD8+ T cells post-dosing. Additionally, the magnitude of CD4+ T cell responses were greater for the CPI-refractory than CPI-sensitive subjects, despite a reduced proportion of peptides to which CD4+ T cell responses were measured, suggesting that the breadth and not the magnitude of response could be associated with favorable outcomes.
"We are very encouraged that GEN-009 can generate broad and diverse immune responses through ATLAS-selected neoantigens" said Thomas Davis, M.D., Chief Medical Officer of Genocea. "The deepened and durable responses in the CPI-sensitive patients and durable disease control in refractory patients are notable. We believe the cumulative long-term GEN-009 data continues to support our unique approach to identifying clinically meaningful immunotherapy targets and provides a strong foundation for our novel cell therapy candidate, GEN-011, which can target up to 30 ATLAS selected neoantigens and is currently in the clinic."
ASCO POSTER SESSION: Developmental Therapeutics – Immunotherapy
Abstract 2613: View Source
Title: Long term results from a phase 1 trial of GEN-009, a personalized neoantigen vaccine, combined with PD-1 inhibition in advanced solid tumors
GEN-009 is an adjuvanted personalized neoantigen vaccine being evaluated in eligible patients with advanced cancer who received standard-of-care (SOC) PD-1 checkpoint inhibitor (CPI) +/- chemotherapy during vaccine manufacturing and received 5 vaccine doses over 6 months along with continuation of PD-1 CPI. Genocea’s proprietary ATLAS platform selects tumor neoantigens for synthesis into GEN-009 peptides and identifies each patient’s own peripheral blood T cells and antigen-presenting cells. Patients who progressed prior to vaccination could receive alternate therapy followed by GEN-009 alone or in combination with a salvage regimen, as well as accelerated vaccine dosing. The contributions from GEN-009 are assessed using each patient as their own control based upon changes in tumor volume pre- versus post-vaccination.