Dr. Muhammed Murtaza:
It's hard to pinpoint exactly where it started, right, but I'll give you an example of, you know, that I often refer to in patients with cancer. I think if you go back to the early 2000s in patients with lung cancer, there was a new class of drugs that was developed. They're called EGFR inhibitors, right, that inhibit this very particular gene in lung cancer, and initially when the trials came out, it looked like this would be of minimal benefit for the average lung cancer patient, but what it turned out was there was a small group of patients that was actually benefiting quite well from this drug, and what scientists discovered at the time, this is sort of, again, the early-to-mid-2000s, is that if you take DNA from these patients' tumor and you sequence them, the ones that benefit have a mutation in their EGFR gene, and so you can identify this subgroup of patients, and you know, more precisely take this decision to give them this therapy. Fast forward about 20 years, now we can even do this from blood samples. So, instead of actually trying to get a tumor biopsy, you can actually take blood samples at various time points in their treatment course, and not just say which patients will benefit, but when is the right time to give them the drug and when is the right time to stop it?