Independent research may change the immunotherapy game

Immunotherapy treatments that focus on the PD-L1 protein have become some of the most exciting to emerge in cancer treatment

The trouble with these treatments is that they are not fully understood and that has led to some disappointing results for everyone involved in trialling their treatments. Bristol Myers-Squibb’s Opdivo and MSD’s Keytruda, the leaders of the market, have both had major shock failures in the clinic.

Now, two studies published in Nature may be able to explain some of the reasons for this and potentially offer a way to boost the success rates of the PD-L1 inhibitors. The studies, that were submitted by teams independent of each other, both found that there was another player alongside the PD-L1 protein that enables cancer cells to avoid destruction by T-cells, molecules known as CMTM6 and CMTM4.

The two CMTM proteins had previously served an unknown function but were discovered to regulate the PD-L1 protein. The molecules are therefore able to enhance the ability to inhibit the action of T cells in the body’s defence against tumour cells.

 "We always thought PD-L1 was a loner at the cancer cell surface, but it turns out that it binds to another protein", says professor Ton Schumacher, an author of the study, at the Netherlands Cancer Institute. "This other protein, called CMTM6, stabilizes PD-L1 and thereby increases the capacity of cancer cells to inhibit the immune response."

As a result, this breakthrough could provide new clues in how best to target patients suitable for PD-L1 immunotherapies. It could potentially lead to a new target for immunotherapy treatment or even a combination treatment that targeted both the PD-L1 protein and the CMTM6 protein.

The potential to make immunotherapy treatments more reliable and more effective should see pharmaceutical companies take a real interest in moving this research forward.