ctDNA & MRD: Current Applications, Limitations & What’s Next

Thank you, Karine.

Really, I think that as we had discussed before, the liquid biopsy or circulating tumor DNA has now a lot of applications.

It has applications for metastatic patients, and that's in the upfront initial genotyping of the patient so that we can figure out the right treatment strategy as the first-line treatment.

I spoke a little bit about resistance profiling, where at the time of progression, one of the first liquid biopsy treatments technologies was approved because of the identification of this very specific resistance profile with the T790M and EGFR.

So in the metastatic setting, that picture and that patient journey and that evolution of the applications has been quite linear and important and facilitatory for the practical management of patients day-to-day in the clinic.

I think one of the other areas that really has been a holy grail and one of the areas that has driven a lot of pursuit is, can cancer be identified earlier and be more definitively treated earlier to really enhance the chance of cure? And I think that brings us into the concept of MRD, where MRD refers to minimal residual disease or a small amount in cancer that may exist after surgery or some other type of definitive strategy and treatment, and our decision about do we do adjuvant treatment or not.

So there are many trials now that are looking at this concept.

Some are looking at it in locally advanced patients.

So I'll reference in lung cancer after the Pacific regimen, which is chemotherapy and radiation for stage three or in resectable small cell lung cancer, their applications to look at an MRD to consider whether or not a patient gets consolidation immune therapy.

But most conventionally, this is being looked at in post-surgical scenarios.

It's being looked at in breast cancer, colon cancer, lung cancer.

Even now, the concept of MRD has an FDA approval with the Signatera assay to guide MRD testing for breast cancer.

And so the field has moved a lot.

I think one of the challenges is that people are still waiting to see overall survival data and how using the MRD test will influence and change overall survival.

And I think that's where we're at right now.

That's where some of the clinical trials are speaking to.

And at this stage, it's still being investigated.