Genocea presents GEN-099 results, update on GEN-011 program

Genocea Biosciences presented four posters that collectively validate the company's unique and differentiated approach to identifying clinically meaningful immunotherapy targets at The Society for Immunotherapy of Cancer 35th Anniversary Annual Meeting taking place virtually November 9th - 14th. In follow up to data shared at the European Society for Medical Oncology Virtual Congress 2020, the company shared expanded clinical and immunogenicity findings from Part B of its ongoing GEN-009 Phase 1/2a trial, which evaluates GEN-009, Genocea's neoantigen vaccine, in combination with PD-1 inhibitors in advanced cancers. Posters 390 and 413 outline the clinical and immune responses elicited by GEN-009 in 16 checkpoint inhibitor therapy sensitive and resistant patients. Poster 413 was a highly scored abstract selected for a "Poster Walk." Of the nine CPI-sensitive patients, three patients experienced a novel reduction in tumor volume post-GEN-009 dosing and achieved independent RECIST responses after vaccination, including 2 PRs and 1 CR. Five additional CPI-sensitive patients have shown disease control post-vaccination for up to 11 months. Within the CPI-resistant population, five of seven patients appear to have stabilized disease lasting up to seven months. GEN-009 elicited strong anti-tumor immune responses with both CD4+ and CD8+ T cell responses observed at day 50 post-vaccination and with peak ex vivo responses occurring Day 92. Early data from two patients tested so far show a complete absence of circulating tumor DNA by day 50, which is consistent with a vaccine clinical effect. There was also emerging evidence of epitope spreading in patients who successfully responded to therapy. GEN-009 was safe and well tolerated. One distinguishing feature of Genocea's proprietary ATLAS technology is its ability not only to identify the stimulatory neoantigens to include in GEN-009 and GEN-011, but also to reveal Inhibigens - peptides that elicit T cell responses with the capacity to compromise anti-tumor immunity. Poster 526 delves further into the biology of Inhibigen-specific responses and reveals important insights that add to the company's growing body of knowledge beyond data previously shared at the AACR Virtual Annual Meeting II. Findings in mice and humans confirmed the presence of Inhibigens in nearly every sample screened, and mouse data show the abrogation of anti-tumor activity in response to otherwise protective vaccines is associated with decreased CD4+ and CD8+ T cell, macrophage and dendritic cell infiltration into tumors. This outcome may be attributed to abolished cytokine activity in response to tumor-specific vaccine antigens. The data also show that vaccination with an Inhibigen renders CPI co-administration ineffective. Poster 149 highlights important advantages of GEN-011 over TIL and TCR-T therapies. GEN-011 has been developed with 100% manufacturing success at clinical scale via PLANET(TM), a process designed to deliver billions of NPTs for every patient. The 16 PLANET runs conducted to date have confirmed GEN-011 comprises over 98% of highly functional, non-exhausted T cells with a mean neoantigen breadth of response nearing 90% of intended targets. In contrast, recent reported data from TIL products showed responses to less than 10% of intended neoantigens. GEN-011 NPTs have an unparalleled breadth of neoantigen coverage, targeting up to 30 relevant antigens. The drug product also avoids pro-tumor Inhibigens that may hinder clinical responses and the PLANET process does not require extra surgery or viable tumor.