Recent research shows that REOLYSIN demonstrates upregulation of immune checkpoint marker PD-L1 in post treatment tumours. This finding was presented in a poster presentation made by Dr. Devalingam Mahalingam of the Cancer Therapy and Research Centre, University of Texas Health Science Centre San Antonio this July.

Why did we mention this discovery as one of the highlights of our second quarter? After all, on their own PD-1 and PD-L1 can actually help cancer cells hide from the body’s immune system—that is, until these cancer cells are revealed and targeted by a new class of drugs called checkpoint inhibitors. In this blog post we’ll explain how this works and how REOLYSIN may help checkpoint inhibitors improve the immune system’s ability to fight cancer cells.

The Challenge:
PD-1 and PD-L1

Often, a tumour cell will produce a compound called PD-L1, which can then be found on the surface of the cell. Under certain circumstances, the tumour cell will also cause the white blood cells that form part of the immune system to produce (or “up-regulate”) a compound called PD-1. When a white blood cell is close to a tumour cell, the PD-1 and PD-L1 bind to one another, resulting in the “blinding” of the immune system to the presence of the tumour cells.

A New Opportunity:
Checkpoint Inhibitors

There’s a new class of drugs, called checkpoint inhibitors, that bind to either the PD-1 or PD-L1 (depending on the drug), thereby allowing the immune system to “see” the cancer cells again — and to try to eliminate the cancer.

How REOLYSIN may improve the effectiveness of Checkpoint Inhibitors

REOLYSIN has been shown to increase PD-1 and PD-L1 levels in patients with a variety of cancers. Higher levels of PD-1 and PD-L1 are generally thought to make checkpoint inhibitors work better. Drugs that increase PD-1 and PD-L1 should then be useful in improving the effectiveness of checkpoint inhibitors through combination therapy.

What’s next for REOLYSIN and Checkpoint Inhibitors?

We soon plan to enter into clinical trials in which cancer patients are treated with REOLYSIN in combination with a checkpoint inhibitor. These trials will seek to determine whether REOLYSIN helps the checkpoint inhibitor work better.

If you’re interested in learning more about this topic, read more about our findings here: