Colorectal Cancer Made Visible to Immune System

A new technique has made it possible for the first time to make colorectal cancer 'visible' to the immune system and therefore vulnerable to its attack through immunotherapy . This is an important result, since this treatment, effective in other forms of cancer such as melanoma and kidney cancer, works in less than 5% of cases for colorectal cancer. The result, published in the journal Cancer Cell, is due to the international study led by Italy with the Istituto Fondazione di Oncologia Molecolare Airc of Milan and the Universities of Turin and Milan, in which the San Raffaele Hospital of Milan, the Oncology Institute of Candiolo (Turin) and the Milanese company Cogentech also participated. The technique has also been tested in the United States on 18 patients , with encouraging results. "For about 10 years in our laboratories we have been studying a category of tumors that have a defective DNA repair system ," says Alberto Bardelli, scientific director of Ifom and professor at the University of Turin, who coordinated the researchers together with Giovanni Germano, of Ifom and professor at the University of Milan. "These tumors are particular - continues Germano - because due to this defect they accumulate hundreds of mutations that attract the attention of the immune system ." The goal was, therefore, to make colorectal cancer, considered 'cold', more similar to this so-called 'hot' type, which immune cells can attack more effectively. The turning point came when studying the mix of two drugs : temozolomide , which damages the DNA of tumor cells, and cisplatin , which instead forms bonds with the DNA. To escape the destructive action of this pair, tumor cells reduce their ability to repair damage to DNA , but this defense mechanism turns into a weak point: "The cells accumulate a very high number of mutations - concludes Germano - and thus make themselves recognizable and attackable by the immune system ."