For example, if you're looking for kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation, there were polymerase chain reaction (PCR) tests looking only for that. You know, initially, we began testing the tumor for a specific gene alteration. Ramaswamy Govindan, MD: Once again, a great question. PT Staff: Could there be other (better?) ways to use genomic tests? And you're so right that we do need sequencing the cells to place them on the property at trials. So we do the sequencing in some instances multiple times over the course of the life of a patient. It's important to study not only what happened to begin with, but also when the drugs stopped working, and then you can place them on appropriate clinical trials. So a given tumor with the EGFR-mutant lung cancer may have amplification of a gene called methyltransferase 1 (MET1) for instance, or may have picked up a secondary mutation- the same EGFR gene that may have accounted for resistance- when there's drug therapy stopped working. We now biopsy those tumors doing the sequencing again because the mechanism of resistance varies depending on various situations. Let's say a year or 2 goes by and the tumor cells become resistant. For example, the same EGFR-mutant patients, they give EGFR inhibitor therapy. And now we are coming up with better drugs, or drugs that may work in the setting where the initial drug for a particular gene alteration stopped working.Īnd so we have a number of clinical trials, as you mentioned, and for us to place patients on a specific trial is not only important-what are gene alteration that tumor cells had to begin with- but what subsequent alterations have taken place. And even if these patients take these pills for a year or 2, eventually these tumor cells escape the effects of these drugs and become resistant to this. I wish we could say that, but we are not there at this point. And, you know, unfortunately, when you have somebody with EGFR-mutant lung cancer, for example, I wish I could tell you take this pill for 10 days and all your lung cancer can be cured. Ramaswamy Govindan, MD: That's also an excellent question, to be honest with you. PT Staff: How does genomic sequencing inform clinical trial eligibility?
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