This week we are at the 2015 ASCO Genitourinary Cancers Symposium, held in Orlando, Fla. Our collaborators are presenting three studies that demonstrate how the Epic Sciences no cell left behind™ platform could be used as a blood test for certain types of metastatic prostate and bladder cancers — liquid biopsies to predict which patients will best respond to certain therapies before they are treated.
Today’s blog post highlights one of our studies presented at this week’s meeting:
Patients with muscle invasive or metastatic bladder cancer face poor prognoses and few treatment options. Recent studies have shown that new medicines targeting a protein known as PD-1 and PD-L1 might help these patients. Many cancers make an overabundance of PD-L1. The protein binds to PD-1, a receptor found on the surface of a type of T cells, a component of the immune system.
Normally, PD-1 keeps T cells in check, so they don’t cause autoimmune reactions. But many cancer cells take advantage of this protective mechanism by displaying PD-L1 on their cell surfaces. The interaction between these nefarious PD-L1 proteins and PD-1 on T cells tells the T cells to leave the cancer cells alone.
Many pharmaceutical companies are working on new cancer drugs that target PD-L1 and PD-1 (read more here). But not all bladder cancers express PD-L1. For those patients, these potential therapies may not work.
To identify patients who might benefit from PD-1- or PD-L1-targeted therapies, we developed a blood test to detect these molecules in circulating tumor cells and white blood cells. Out of the 17 patients with muscle invasive or metastatic bladder cancer tested using our no cell left behind™ technology, five had detectable circulating tumor cells and three of those patients had cells that express PD-L1. Six of the 12 patients had high numbers of PD-L1 in their white blood cells at four times the levels found in healthy blood donors.
Now that the research has demonstrated that we can detect circulating tumor cells and PD-L1 in patients with muscle invasive and metastatic bladder cancer, we are planning further studies to assess how PD-L1-positive patients respond to therapy that specifically targets those molecules.