The Zona Pellucida (ZP) is a glycoprotein layer surrounding oocytes (egg cells) in the ovary, which plays an essential role in fertilisation and implantation of the embryo. The human ZP layer consists of four glycoproteins, ZP1-4, of which the expression is restricted to oocytes, while ZP3 has also been detected in intermittent developmental stages of spermatocytes (sperm cells). Past efforts of developing anti-ZP glycoprotein based immune contraceptives implied a high level of safety, with immunogenicity observed only in the ovary.
In collaboration with the Institute of Biomedicine at the University of Turku, Finland, Pantarhei unexpectedly discovered that a number of cancer types, such as ovarian cancer, prostate cancer, breast cancer and (non-small cell) lung cancer express ZP3 protein. In combination with the highly restricted expression in healthy tissue, this makes ZP3 an interesting target for immunotherapy in different types of epithelial cancers. An initial proof of principle study in a mouse model of granulosa cell ovarian cancer using ZP3 as immunotherapeutic target showed promising results for tumor growth prevention and inhibition.
Recently, Pantarhei discovered that tumor cells express a unique ZP3 RNA transcript that generates an intracellular ZP3 cancer associated antigen, which we named ZP3C (for ZP3-Cancer). ZP3C mRNA expression is highest in ovarian, colorectal, prostate, breast and lung cancer, while it is virtually absent in healthy tissues. Based on these findings, Pantarhei has patent protected the use of the ZP3 cancer antigen for the treatment of ZP3C expressing cancers.
Currently, PRO is looking for partners to develop ZP3C immunotherapy for active immunisation in cancer patients.