ImmunityBio's Prostate Cancer Vaccine Shows Early Signs Of Clinical Activity, Durable Stable Disease

ImmunityBio Inc IBRX has announced the publication of Phase 1 study data of its Ad5 PSA/MUC-1/ brachyury-based immunotherapy vaccine for metastatic castration-resistant prostate cancer.

• Journal of ImmunoTherapy of Cancer (JITC) published the data. 
• ImmunityBio’s hAd5 is designed to deliver tumor-associated antigens or TAAs, and neoepitopes (expressed only by cancer cells) and can induce T-cell memory due to the activation of both CD4+ and CD8+ T cells along with antibody (or humoral) responses.
• The findings showed that T-cell-mediated immunity was induced in 100% of 17 prostate cancer patients whose white blood cells were evaluated in the study.
• Furthermore, repeated administration was associated without any adverse effects at the dose of 5x 1011 viral particles, supports the application of this hAd5 platform in both cancer and infectious diseases such as COVID-19.
• The vaccine was safe and well-tolerated with no grade severe/serious treatment-related adverse events or dose-limiting toxicities observed.
• Recommended Phase 2 dose was 5×1011 viral particles administered three times repeatedly every three weeks.
• One patient achieved a partial response (PR), five patients had confirmed stable disease (SD) for greater than six months, with a confirmed decline in tumor-related antigens.
• Median progression-free survival was 22 weeks. Median overall survival was not reached, and the 12-month overall-survival probability for all patients was 83.3%
• 100% (17 out of 17) of patients mounted T-cell responses to at least one tumor-associated antigen, and 16 of 17 (94%) patients developed T-cell responses to more than one antigen encoded by the vaccine.
• Price Action: IBRX shares are down 4.73% at $25.51 in market hours on the last check Monday.