CAVATAK

Cavatak is the trade name of Coxsackievirus A21 (CVA21). It is a human virus that occurs naturally in the community, and was first isolated over 50 years ago. Infection by CVA21 is often symptomless; when it does produce illness it is associated with a common cold-like illness.

In order to infect a cell, CVA21 must first attach to the outside of a cell, using a specific ‘receptor’ on the cell’s surface (like a key fitting a lock). CVA21 uses two receptors to infect cells, ICAM-1 (Inter cellular adhesion molecule 1) and DAF (decay accelerating factor). These receptors occur in far higher numbers in metastatic melanoma cells than in normal cells.

As ICAM-1 is not present to any significant extent on normal tissue cells, this confers a high degree of specificity on the oncolytic action of the viruses (ICAM-1 is also sometimes present in increased amounts in other cancer types, including breast cancer, prostate cancer, colon cancer and multiple myeloma).

Once infected, melanoma cells die because of the mechanical disruption caused by massive viral replication and because the infiltration of the virus triggers ‘apoptosis’ (programmed cell death). Large numbers of the virus are then released, and can infect other melanoma cells.

Research To Date
Laboratory and animal studies have shown that:
  • human melanoma cells had on high levels of ICAM-1/DAF and were highly susceptible to rapid destruction by CVA21 whereas blood lymphocytes were unaffected
  • in live SCID mice (mice without a normal immune system) the tumour burden was rapidly reduced following a single injection of CVA21
  • in live laboratory mice, tumours which were away from the site of virus injection also showed effects of destruction by the virus.

This implies that virus growing in the injected tumour has spread through the blood to infect the distant tumour.

These studies encourage the prospect that Cavatak may have a future role in the treatment of melanoma (and other cancers) in humans and particularly exciting is the prospect that spread of microscopic disease could be minimised through the targeting action of the virus via the blood stream.

There has been limited use of Cavatak in humans. A Phase 1 study commenced in 2005. In this study, patients with metastatic melanoma (melanoma that has spread to other parts of the body) receive a single dose of CVA21 injected into the tumour. Further human studies are planned.

Publications
Refer to the Scientific Publications page for a list of published articles about this product.