EpCAM-specific vaccine response by modified antigen and chimeric costimulatory molecule in cynomolgus monkeys.

Immunization against tumor-associated antigens is a promising approach to cancer therapy and prevention, but it faces several challenges and limitations, such as tolerance mechanisms associated with self-antigens expressed by the tumor cells. Costimulatory molecules B7.1 (CD80) and B7.

Optimized expression and specific activity of IL-12 by directed molecular evolution.

DNA delivery of IL-12 has shown promise in reducing the toxic side effects associated with administration of recombinant human (h)IL-12 protein while maintaining the ability to inhibit tumor growth and abolish tumor metastases in animal models. We have developed a more potent version of IL-12 by using DNA shuffling and screening to improve its expression in human cells and specific activity on human T cells. The most improved evolved IL-12 (EvIL-12) derived from seven mammalian genes encoding both the p35 and p40 subunits of IL-12 showed a 128-fold improvement in human T cell proliferation compared with native hIL-12 during the initial screening of supernatants from transected cells.

Chimeric co-stimulatory molecules that selectively act through CD28 or CTLA-4 on human T cells.

CD28 and CTLA-4 (CD152) play a pivotal role in the regulation of T cell activation. Upon ligation by CD80 (B7-1) or CD86 (B7-2), CD28 induces T cell proliferation, cytokine production, and effector functions, whereas CTLA-4 signaling inhibits expansion of activated T cells and induces tolerance. Therefore, we hypothesized that co-stimulatory molecules that preferentially bind CD28 or CTLA-4 would have dramatically altered biological properties.