A next generation DNA vaccine coding for immunodominant sequences of alpha-enolase to cure pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is still an urgent medical need with little advances in therapy and patient survival. By proteomic approach we have identified the tumor associated antigen (TAA) alpha-enolase (ENO1), a glycolytic enzyme overexpressed in PDA that also acts as plasminogen receptor, as immunological target for PDA immunotherapy.
Since ENO1 supports anaerobic proliferation, promotes cancer invasion and elicits a humoral and cellular response in patients, we have developed a non-integrating plasmid DNA vaccine that encodes for full-length human ENO1 (FL-ENO1- DNA vaccine) that efficiently delayed tumor progression in mice engineered to spontaneously develop PDA (KC and KPC mice), and even more in combination with chemotherapy. FL-ENO1-DNA vaccine induces a strong coordinated anti-tumor immune response that is associated to a reduced influx of regulatory T cells and myeloid derived suppressor cells (MDSC) in the tumor tissue. These data support the idea that ENO1 vaccination represents a suitable therapy to prevent PDA relapse reduce tumor burden. However, FL-ENO1-DNA vaccine did not completely eradicate PDA as in vaccinated KC and KPC mice, MDSC and regulatory T cells arose again, and tumor eventually ensues.
To optimize the ENO1 vaccine, the three most immunogenic sequences of ENO1 were identified, and cloned into clinical approved pVax plasmid (ENO3PEP-vaccine). Patent application of this next generation vaccine was filed in September 2021 (MSE, IT n. IT102021000024779). Our preliminary data showed that, ENO3PEP sequences induced a higher T cell proliferation and ratio of secreted IFNg/IL10 in healthy and PDA patient¿s T cells, compared with full-length ENO1. In addition, in KPC mice, ENO3PEP-vaccine induced a higher i) reduction of pancreatic tumor lesions, ii) production of anti- ENO1 IgG, iii) secretion of IFNg by ENO1-stimulated T cells and iv) infiltration of CD8+ T cells at tumor site compared to FL- ENO1-vaccine.
This project aims at the validation of ENO3PEP as second generation of DNA vaccine suitable for immunotherapy in virtually all PDA patients. This will be achieved by: i) phenotypic, functional and transcriptional analysis of the response induced by ENO3PEP in lymphocytes from PDA patients; ii) evaluation of the effects of ENO3PEP DNA vaccination in PDA mouse models in terms of tumor growth, immune response and tumor microenvironment modifications; iii) toxicology and bio distribution studies employing a Good Manufacture Practice (GMP)-like batch of ENO3PEP-vaccine. A safe, greater and long-lasting anti-tumor immune response induced by ENO3PEP vaccine compared to FL-ENO1-vaccine is expected togethe with a substantial step forward to industrialization with an increase of Technology Readiness Level (from 4 to 6-7).
Our project aims at tackling an important health-related challenge, PDA, bringing together knowledge and technologies across basic and clinical expertise. The completion of this program will allow gather data for filing the first-in man clinical study authorization and renders the patent-pending ENO3PEP-vaccine more attractive to investors.