Zona Pellucida (ZP)

Zona Pellucida for cancer immunotherapy

The Zona Pellucida (ZP) is a glycoprotein matrix layer around the oocytes (egg cells) in the ovary, that plays an essential role in fertilisation and implantation of an embryo. The human ZP layer contains four different immunogenic glycoproteins (ZP1-4), that are specific for the ovary and do not occur anywhere else in the female or male body, implying potential safety (no cross-reactivity) when ZPs are used as immune target.

In collaboration with the Institute of Biomedicine at the University of Turku, Finland, Pantarhei Oncology (PRO) has discovered that some malignant tumours such as ovarian and prostate cancer and several other cancers express ZP3 antigens abundantly in 60-90% of the cases in the primary tumour as well as in metastases.

Based on these findings, PRO has patent protected the potential use of ZP antigens for the treatment of ZP expressing cancers. Since earlier unpublished research has shown that ZP3 is the strongest immunogen, the treatment concept is focused on active and passive immunisation against the ZP3 antigen. The demonstration of expression of ZP3 by a tumour is a biomarker for treatment.

Proof of principle of ZP3 immunotherapy was obtained in a transgenic animal mouse model for granulosa cell ovarian cancer. A mixed humoral/cellular response was demonstrated preventing the formation of tumours as well as reducing the size of existing tumours and preventing the occurrence of metastasis. The ovarian cancer application of ZP3 immunisation has been exclusively licensed out to HRA Pharma S.A. in France. All other applications, including those for advanced and metastatic prostate and other ZP3 expressing cancers have been retained by PRO. Preclinical studies are in progress for the active immunisation route by HRA Pharma. PRO is looking for partners to develop ZP3 antibodies for passive immunisation for other applications.