For Strata Oncology, clinical diagnostics is critical for the move to a precision medicine model.
By Chris Wolski
Every patient is different; an individual with a unique biological makeup. Precision medicine is built on this foundation—finding the right treatment expressly for that unique individual’s specific needs.
Delivering precise treatment is reliant on a number of factors, including advanced clinical diagnostic tools.
Strata Oncology has developed such a tool to help clinicians identify the precise course of treatment for cancer patients. CLP recently sat down with Dan Rhodes, PhD, co-founder and CEO of Strata Oncology, to discuss the promise and challenges facing precision medicine, how its Strata Select solution is helping clinicians develop precise treatments, and what clinical diagnostics looks like in the future.
Rhodes’ answers have been edited for length and clarity.
CLP: Sometimes, I think “precision medicine” is a bit of a buzzword. Can you dive in a bit and discuss from your perspective how precision medicine—and particularly precision oncology—is advancing modern diagnostics and medicine in general?
Dan Rhodes: The idea of precision medicine is a simple one. The right drug for the right patient at the right time. But it’s not that simple to implement in practice, especially when the biology behind a patient’s treatment response is complex.
In the first wave of precision oncology, a large number of new targeted therapies were developed. Targeted, in that they were directed against specific mutations known to cause cancer. The diagnostic challenge in this case is quite manageable, you simply look for the targeted mutations in a patient’s tumor, and can then easily identify those patients likely to respond.
For many of the more recent treatment advances—such as immunotherapy and antibody-drug conjugates—the biology is not so simple. We are no longer targeting a specific single mutation known to cause the cancer, but instead are looking to unleash the immune system against the cancer (in the case of immunotherapy) or target antigens expressed on a tumor cell and deliver a chemotherapeutic payload (in the case of antibody-drug conjugates).
For these types of treatments, to accurately predict response, we need diagnostic strategies that can simultaneously measure all of the aspects of biology that may be important for a patient’s response. It’s this challenge that we have been focused on at Strata, advancing multifactorial biomarkers that capture the complex biology required for a tumor response. This requires moving beyond single gene markers and measuring many genes—both at the DNA sequence level and also at the RNA expression level—and combining them into predictive algorithms learned from patient outcome data.
It’s strategies like this that will be required to realize the full potential of precision oncology, and for patients battling cancer, this means a greater potential for positive clinical outcomes and fewer side effects.
Another big theme in precision oncology is treating the biology instead of the tissue of origin. For decades, we have treated cancer one tumor type at a time. One treatment regimen for lung cancer, a different one for colon cancer, a different one for breast cancer, and so on. Now, in the precision era, we’re looking for common biology that is predictive of tumor response across tumor types—a so-called “tissue agnostic” approach.
We’ve seen good evidence for this approach with targeted therapies that are now approved for patients with specific gene mutations, independent of tumor type. At Strata, we’re looking to take this a step further and advance multi-dimensional biomarker algorithms predictive of treatment response to therapeutic modalities like immunotherapy or antibody-drug conjugates across tumor types as well. We expect this theme to continue to mature.
CLP: So, with that in mind, can you detail how Strata Select works?
Rhodes: Strata Select is a pan-solid tumor molecular profiling test for patients with advanced cancer. It combines simultaneous DNA and quantitative RNA sequencing from a single small tumor tissue sample and includes a collection of predictive algorithms to guide treatment selection for immunotherapy, as well as other classes of therapy.
Strata Select is a laboratory-developed test (LDT) and is carried out in our CLIA-certified, CAP-accredited lab in Ann Arbor, Michigan. Results are returned to physicians within 10 calendar days of us receiving a patient’s tumor tissue sample.
Immunotherapy response prediction is based on the Immunotherapy Response Score, a proprietary, pan-solid tumor predictive biomarker for anti-PD-1/PD-L1 checkpoint inhibitor monotherapy benefit that has been validated in multiple publications, by us and independent research groups.
Strata Select also provides genomic signatures and comprehensive genomic profiling results that can be used to guide genomic-alteration targeted therapies. Supplemental RNA expression-based results provide insights that can be informative for other classes of therapy, such as antibody-drug conjugates.
Our platform is proven to provide results from small and challenging tumor tissue specimens, including diagnostic and metastatic biopsies, fine needle aspirations, and fluid cytology. We require 10 times less tissue than other tests that doctors may be currently using for comprehensive genomic profiling to guide treatment selection.
CLP: Interestingly you’re getting reimbursement from Medicare for Strata Select. How did you achieve this and how important is it to the success of your test?
Rhodes: Strata Select is the first test incorporating an immunotherapy biomarker algorithm to be covered by Medicare across solid tumors meeting specified coverage criteria.
We gained Medicare coverage by submitting a comprehensive application and validation package, including our peer-reviewed data, to the MolDX Program administered by Medicare contractor Palmetto GBA. We received a positive coverage determination under the existing policy, “Next-Generation Sequencing for Solid Tumors.”
Coverage and reimbursement for our test is, of course, important to our business, but what’s most important is ensuring that all patients with cancer have access to testing that can help them get the best possible therapy for their specific illness. Medicare coverage ensures this access for many patients with advanced cancer.
For patients with non-Medicare insurance, or those who are uninsured, we have a robust financial assistance program that often covers all out-of-pocket costs for patients—90% of patients pay $0.
CLP: You’ve described the Strata Select test as a complementary diagnostic. What’s the difference between a complementary and companion diagnostic? Is a companion diagnostic in your plans?
Rhodes: Companion diagnostics are typically linked to a specific drug within its approved label. Complementary diagnostics, on the other hand, are associated more broadly, usually not with a specific drug but within a class of drugs, and not confined to specific uses by labeling.
Instead of being a requirement for safe and effective use of a medicine, complementary diagnostics identify biomarker-defined subsets of patients that respond particularly well to a drug and can aid in risk/benefit assessments for individual patients.
That’s exactly what the Immunotherapy Response Score does—it gives physicians important information about how a patient’s tumor may or may not respond to anti-PD-1/PD-L1 immunotherapy to help guide their treatment decisions.
We are certainly exploring a variety of pathways for further expansion of the impact of Strata Select, the Immunotherapy Response Score, and the other multivariate treatment selection algorithms we have developed.
The most important thing for us, however, is that we get validated biomarker tests into the hands of physicians as quickly as possible so that they can use this information to give their patients the best possible care.
CLP: Let’s look ahead, what do you think clinical diagnostic testing for cancer is going to look like in the next five to 10 years?
Rhodes: I believe that five years from now, it will be standard of care—required—to test tumor tissue from every patient with cancer to guide their optimal therapy. And I believe that testing is going to suggest a precision medicine with a high likelihood of response for most patients. Ultimately, that means better outcomes.
There’s been talk about this paradigm for years, but still it is the exception and not the rule outside of a few tumor types. A lot of that is driven by lack of access and lack of actionability.
But I see a clear path to development of new biomarkers for medicines across therapeutic classes and testing technology that meets the needs of real-world clinical scenarios.
Chris Wolski is chief editor of CLP.