He is therefore looking for ways to make the tumors susceptible to his own immune system. Van Hall has been appointed professor of Experimental tumor immunology in Leiden from 1 June, in particular tumor escape mechanisms.
‘Always fascinated by immunology and defense’
Van Hall has always been fascinated by immunology and the immune system. In 1994 he started his PhD at the Leiden University Medical Center (LUMC). “I wanted to know how we could use the immune system to fight diseases such as cancer.”
Not believed in defense
At that time it was not so obvious to delve into this. “At the time it was not believed that the immune system could mean anything against cancer, it was not taken seriously.” This changed about ten years ago when the first patients with pigment cell cancer were treated with immunotherapy. “Everyone was suddenly very enthusiastic when it turned out that it was catching on.”
(In) visible tumors
Today’s own immune system is increasingly used to treat tumors. But then the immune system must know that there are tumor cells in the body. “It is actually a kind of cat and mouse game,” says Van Hall. Tumors try to remain as invisible as possible so that they are not recognized by the immune system. For example, some tumors do not produce the proteins by which the immune system can recognize them. ‘
Coincidentally, Van Hall and his team discovered that these tumors were not so invisible after all. ‘We were the first to identify proteins on these tumor cells, so that the immune system could still recognize them. We call these proteins TEIPPs. ‘ In the coming years, Van Hall wants to investigate whether a therapeutic vaccine with these proteins elicits an immune response against the tumor cells in patients with lung cancer. The first clinical studies will start shortly.
Defense cells less effective
In addition to making themselves invisible, some tumors can inhibit the activity of the immune system. For example, they express certain proteins that bind to the NKG2A receptor on immune cells making them less effective. “We were one of the first to demonstrate that we could increase the activity of immune cells by blocking the NKG2A receptor.” Clinical studies of this inhibitor are already underway, but Van Hall is more interested in the biology behind it. “In the coming years I want to investigate exactly how this inhibition works.”
Infect tumor cells
In addition, Van Hall is working on a new way to help the immune system in its fight against tumor cells. ‘We use oncolytic viruses for this. These viruses almost only infect tumor cells. Because infected cells are always recognized and cleared by the immune system, they can no longer escape. It is an extra alarm for your body, so to speak, that something is not right and it has to take action. ‘ Van Hall has high expectations for this new approach.