Inovio Pharmaceuticals has announced that an interim data analysis showed that its INO-5150 cancer immunotherapy product generated antigen-specific CD8+ killer T cell responses measured in peripheral blood from subjects with biochemically recurrent prostate cancer. The immunology results demonstrate that INO-5150 treatment as a monotherapy generated prostate specific antigen (PSA) and prostate specific membrane antigen (PSMA) specific T cell responses in peripheral blood in 60% (35/58) of the subjects. Moreover, patients with specific CD8+ T cell responses experienced dampening in the rise of PSA and significant increases in PSA Doubling Times (PSADT). PSA is a prostate cancer associated biomarker and positive changes on PSA levels could signal INO-5150’s potential positive impact on the treatment of prostate cancer.

These results were presented as a poster discussion on September 10th at the 2017 European Society of Medical Oncology (ESMO) meeting in Madrid, Spain.

Dr. Neil Shore, MD, Medical Oncologist at Urologic Associates of North Carolina, and the principal investigator of this study said, “Immunotherapy is an exciting new approach being evaluated for the treatment of many cancers including prostate cancer, where a small subset of patients have been shown to demonstrate clinical benefit from such therapy in the form of checkpoint inhibitors. Our study provides encouraging immunologic and clinical data that Inovio’s immunotherapy product can generate antigen-specific CD8+ killer T cell responses in the blood and link such responses to PSA changes in prostate cancer patients. Our results suggest that further evaluation of this product in prostate cancer patients should be explored.”

Dr. J. Joseph Kim, Inovio's president and CEO, said, "As a leader in active immunotherapy for cancer with its lead program in phase 3, Inovio is pleased to report on promising phase 1b clinical trial data of our prostate cancer therapy INO-5150. The immunotherapy’s ability to generate anti-prostate cancer CD8+ T cell responses in patients dosed is truly exciting. Perhaps even more importantly, we also observed that the treated patients with better T cell responses saw a slower rise of PSA levels compared to those without the T cell responses.

We believe the new clinical data positions INO-5150 as an attractive T cell generating immunotherapy component of a potential combination regimen. In this regard, Inovio already has one the most extensive and dynamic T cell immunotherapy combo portfolio in our field, with three different PD-1/PDL-1 immuno-oncology combo efficacy studies with 3 different collaborators – MedImmune, Regeneron, and Genentech for MEDI0457 and INO-5401.”

INO-5150, an active immunotherapy targeting both PSA and PSMA antigens which are present in the majority of prostate cancer cells, is administered with and without INO-9012, Inovio’s DNA-based IL-12 immune activator. INO-5150 is designed to activate patients’ immune responses and to specifically target prostate cancers expressing PSA and PSMA. This open label phase 1b study has fully enrolled 62 subjects with biochemically recurrent (rising PSA) prostate cancer and is intended to assess the safety, tolerability, dosing and immunogenicity of INO-5150 alone or in combination with INO-9012. This multi-centered study is also evaluating changes in PSA levels and kinetics, as PSA is an important biomarker in prostate cancer.

INO-5150 was generated using Inovio's proprietary technology process to enable significant production of PSA and PSMA antigens with genetic sequences differentiated from native human PSA and PSMA sequences. This patented approach is designed to help the body's immune system overcome its "self-tolerance" to prostate cancer cells and mount a strong targeted CD8+ killer T cell response to eliminate the cancerous cells displaying these antigens. PSMA is also one of 3 antigens comprising INO-5401, which is being tested as an immunotherapy to treat glioblastoma multiforme and metastatic bladder cancer in combination with Regeneron and Genentech’s checkpoint inhibitors, respectively.

This poster presentation provided immune response and clinical correlation across all four cohorts. In addition to immune responses, clinical correlative analyses evaluating PSA kinetics showed that patients with specific CD8+ T cell responses experienced dampening in the rise of PSA and significant increases in PSADT. Additional prostate cancer tissue analyses are ongoing to further investigate immunological correlation.