Killer result for Lorus

Scientists at Lorus Therapeutics, a biopharmaceutical company specialising in the research, development and commercialisation of pharmaceutical products and technologies for the management of cancer, have published the results of experimental studies with Virulizin, the company's lead anticancer drug.

Previous preclinical studies demonstrated the antitumour efficacy of Virulizin in human tumour models in mice and a critical role for specialised immune cells called macrophages in the antitumour mechanism of action. The current study, performed in collaboration with the Calcium Research Laboratory, department of medicine, McGill University, examined whether another subset of immune cells called natural killer cells (NK) are also involved in Virulizin antitumour activity.

Examination of tumour tissues at the cellular level demonstrated that human tumours implanted into mice subsequently treated with Virulizin had an increased number of macrophages and NK cells infiltrated directly into the tumour. The increase in NK cell infiltration occurred at an early stage of Virulizin treatment and correlated with an early sign of increased tumour cell killing. Also observed was increased numbers of NK cells in the spleen, the tissue of origin for mature NK cells, and these NK cells isolated from spleen also exhibited increased capacity to kill tumour cells in vitro.

In NK deficient mice, the antitumour activity of Virulizin was compromised, providing additional support to the proposal that NK cells are necessary for Virulizin activity. Depletion of macrophages resulted in a loss of Virulizin-induced NK cell infiltration into tumours, indicating that macrophages stimulate NK cell infiltration into tumours. These results strongly support a mechanism in which Virulizin stimulates immune cells in a coordinated manner, such that they migrate to the tumour and destroy tumour cells.

'In recent years, the scientists at Lorus have produced a number of publications that provide consistent evidence for how Virulizin acts as an antitumour agent. This latest publication adds a critical component to the cellular mechanism of action and sets the groundwork for ongoing molecular studies,' said Dr Jim Wright, chief executive officer of Lorus. 'From a drug development perspective, a solid publication record in respected peer-reviewed scientific journals is an important element in gaining approval for Virulizin from the US FDA.'