Improving Biomarker Testing Rates in Metastatic Colorectal Cancer

Pashtoon Kasi, MD, MS, oncologist, director of colon cancer and liquid biopsy research, Weill Cornell Medicine, discusses why biomarker testing rates are low among patients with metastatic colon cancer, as well as what changes can be made to improve care.

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Welcome back to PopHealth Perspectives, a conversation with the Population Health Learning Network where we combine expert commentary and exclusive insight into key issues in population health management and more.

In this episode, Dr Pashtoon Kasi shares how biomarker testing can improve care and lower costs for patients with colorectal cancer.

Hi, my name is Pashtoon Kasi. I'm an oncologist at Weill Cornell Medicine. I'm the director for colon cancer research here, as well as the director for liquid biopsy research at our Precision Medicine Institute.

How does biomarker testing among patients with cancer affect targeted therapy regimens and treatment decisions?

From a precision medicine standpoint, simplistically speaking, we often tell patients that cancer has to have the lock for which the key may be available to prescribe. Biomarker testing allows for that to happen, by knowing what we call the predictive markers of response to therapy. Not just for later line settings, but even first-line, for a lot of malignancies.

Despite guideline recommendations and proven benefits, why are biomarker testing rates lower among patients with metastatic colon cancer?

It's an interesting topic. It's not like biomarker testing is not pursued. There was a recent paper from my colleagues at Northwestern University, where they looked at US data for basic RAS testing. In that analysis of thousands of individuals with metastatic colorectal cancer, it was surprising that in more than 80% of the cases, the testing wasn't back within 15 days or more.

In my opinion, some of that has to do with the turnaround time and acquisition of tissue-based testing, especially if the sample is not in-house. Even though the test results can take sometimes fewer than 14 days to come back, regarding institutional panels or even commercially available panels, the real-world delay in getting specimen acquisition is a big issue.

There are a lot of hindrances that are punctuating the process, which don’t make the process any easier. The new development of guidelines to include liquid biopsy for genotyping up front is an option, which I think can help overcome this void as we discuss more.

What improvements can be made across the care spectrum to increase biomarker testing rates and improve care?

In many ways, biomarker testing can be viewed in 2 respects. One is that it is ordered by the provider, which is often an oncologist. But I think we, as a scientific community, need to identify opportunities for reflexive testing, especially if we are focusing on colorectal cancer or other GI malignancies.

For example, at a lot of academic and community institutions alike, reflective testing for mismatched repair can and is being done reflexively. For GI cancers and some other cancers, you could argue for information on the PD-L1 CPS, which again, is immunochemistry-based. With the new information on HER2, it's an immunochemistry-based test.

With the recent update of 3 different or 2 blockade regimens in the second line or beyond for colorectal cancer, and the recent results from the MOUNTAINEER study looking at tucatinib plus trastuzumab, you'll only be able to act on these findings if you're testing for the biomarker.

The testing, in my opinion, has to be upfront. Similar to how the data for lung cancer is evolving, it would be more cost efficient and have more value for the tissue as opposed to doing it a la carte one by one. Making use of the least amount of tissue could indicate all the biomarkers. Adopting opportunities for reflexive testing, especially if things are available in-house, can help decrease the turnaround time issue as well as improve the number of people who can get biomarker guideline-recommended testing.

Excellent. Thank you for sharing that, Dr Kasi. What is something you wish payers better understood regarding biomarker testing?

Precision medicine, which obviously goes in hand in hand with biomarker testing. It has been reported for several malignancies that patients who get precision medicine-based therapies all do better in terms of quantity of life, as well as quality of life.

In hoping to give patients something more specific as opposed to generic chemotherapy, you're also identifying who are the ones who may not benefit from an approach or may need escalation or deescalation. I think biomarker testing can provide you with that opportunity.

As clinical oncologists we sometimes run into issues when the biomarker testing, especially commercially based broad NGS panels, is not covered, or patients end up with copay issues. That should not be the case anymore because this small investment up front can save a lot of downstream costs from therapies that may or may not work, by identifying those who may benefit from a treatment or a clinical trial. A lot of the clinical trials in the space are biomarker driven.

Encouraging and making sure adequate guideline-directed and committed biomarker testing is done upfront at diagnosis and down the line when patients acquire mechanisms of resistance, especially if they're exposed to target therapies or immunotherapies—in the long run, this would be a more cost-effective strategy, not just for payers but society as a whole.

I think that's often underestimated, and the awareness is poor on this aspect. By choosing some therapies that are precision medicine-based, you're not necessarily spending more. In the long run, you probably end up spending less.

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This transcript has been edited for clarity.