We recently interviewed Dr. Richard Chen, EVP of R&D and Chief Medical Officer at Personalis, a precision medicine company working on highly sensitive, personalized MRD testing. See the full transcript below.

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1) Hi Dr. Chen, thank you for joining us. To start, could you please share a bit about your background and current work?

I’m the Chief Medical Officer and EVP of R&D at Personalis, and have been with the company since it was founded in 2011. I’ve been in the genomics and diagnostics space for over 25 years, in both industry and academia. I have led strategy, technology and product development and medical affairs at Personalis, including the development of NeXT Personal, our ultrasensitive MRD test.

2) While MRD has been advancing rapidly, it is still a relatively early space, and I have seen many different descriptions of MRD or variations of its full form. How do you define "MRD"?

We now have blood tests that can detect the small traces of residual or recurrent cancer in cancer patients. These tests are often called “MRD” tests, or tests that can detect “Molecular Residual Disease.”  For instance, our NeXT Personal test detects cancer MRD by looking for tiny traces of DNA shed from tumor cells (circulating tumor DNA) in the blood. These tests can be very sensitive and can detect cancer ahead of traditional radiographic imaging.

3) What do you view as the clinical impact MRD can have on patients?

These tests have the potential to profoundly impact cancer patients during their cancer journey. Many cancer patients and the physicians who are caring for them are making decisions under a cloud of uncertainty about the status of their cancer. Did the treatment work? Is the cancer still there? Is the cancer coming back? MRD tests like NeXT Personal can potentially help answer these questions more accurately, and thus help further optimize patient management.  

Having a highly sensitive MRD test has the potential to catch cancer recurrence earlier and enable treating patients earlier. Conversely, a negative MRD test can give the patient and physician additional reassurance and open the door for potentially avoiding unnecessary treatment. What is critical here is that the MRD test has to be highly sensitive for cancer to really help the patient in both these cases. In fact, this is a major technical challenge and NeXT Personal aims to address this and drive the wave of ultrasensitive MRD testing.

4) How do you view the dynamic between different testing modalities or information - for example, imaging vs. MRD testing, and maybe even thinking about genomic profiling information - how should these be layered together or even prioritized?

It makes sense to use MRD testing alongside genomic profiling and traditional imaging. Genomic profiling is typically performed at diagnosis when the physician is trying to decide what therapies may be appropriate for the patient. What is exciting about MRD testing is that it has the potential to help at all phases of the cancer patient journey, from diagnosis to surveillance: tracking neoadjuvant therapy response, assessing cancer risk after surgery, assessing response to adjuvant therapy, and long term surveillance for the patient to catch any early signs of recurrence. Since this is a blood test, one may be able to use it more frequently to monitor the patient than typical imaging, which is part of its appeal. 

5) We talked about MRD for clinical diagnostic use a lot. But the FDA last year had some guidance around ctDNA use for industry - what are your thoughts on MRD's impact in clinical trials or pharma (e.g., as an endpoint in clinical trials for accelerating drug discovery)?

Using MRD as an endpoint is an exciting and very real possibility for clinical trials in the future. One of the things the FDA emphasized was the need for highly sensitive (and specific) MRD tests to enable its use as an endpoint. To support the use of MRD as an endpoint, there is more clinical evidence needed in the industry for each cancer type and stage showing a strong correlation between the MRD test results and patient outcomes, but the data is growing. For example, we had two studies presented at ASCO 2025 showing how NeXT Personal was highly prognostic of patient outcomes after neoadjuvant treatment in early-stage triple-negative breast cancer patients. MRD as an endpoint has the potential to accelerate clinical trials in the future.

6) Are there any barriers to MRD adoption that you see? And if so, any thoughts on how to overcome them?

There is strong growing adoption already, but clinical utility data demonstrating how MRD directly impacts patient outcomes will be important for broader adoption over time. These clinical utility studies can lead to specific recommendations for MRD use in NCCN guidelines, which can also increase adoption. Many of these prospective clinical utility studies are already underway at Personalis and other MRD companies.

7) What are some trends you see in the liquid biopsy and MRD space overall? Anything you forecast or predict in the near future?

This is an incredibly fast-moving space with enormous potential to help patients. I think you will see us and other companies continue to push innovation and performance of MRD tests to benefit patients. For example, the industry has moved toward highly sensitive MRD testing since the introduction of our NeXT Personal test several years ago, but we also believe there is more that can be done to make these tests even more powerful, convenient, and accessible to patients over time.

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