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OncBioMune’s investigational cancer vaccine ProscaVax reduced tumor growth in 70% of prostate cancer patients included in a Phase 1a study. The immunotherapy candidate consists of a combination of the PSA protein (a hallmark of prostate cancer) with the cytokines
— molecules produced by immune cells — interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The clinical trial (NCT02058680) is evaluating the safety and efficacy of ProscaVax in patients with recurrent prostate cancer and increasing prostate specific antigen (PSA) levels, who either have not been treated by or are not responsive to hormonal therapy.
Twenty patients received six intradermal injections of ProscaVax at weeks 1, 2, 3,7, 11, and 15 of treatment. The latest data show that ProscaVax increased PSA Doubling Time (PSADT) in 14 of 20 patients, or 70%. PSADT is the time needed to double the blood level of PSA and a key tool in assessing biochemical and clinical progression. This result indicates reduced tumor growth at a minimum of 31 weeks after the start of ProscaVax treatment. Also at 31 weeks of treatment, 15 of 18 patients showed increased immunity to PSA. Four of the 20 patients who completed ProscaVax therapy exhibited disease progression at 31 weeks. Three of the four did not show increased PSADT. Of note, one patient withdrew from the trial after 19 weeks without disease progression.
The findings add to previously reported positive safety data. Results at 19 weeks of treatment showed that ProscaVax stopped disease progression in 80% of patients. Slowing the PSA elevation, thus increasing PSADT in patients with relapsed and advanced prostate cancer, has been increasingly shown to improve disease prognoses. The company plans to enroll a total of 48 participants in this Phase 1a/1b study and anticipates its completion by December, 2018.