Dr. Nate Pennell discusses "How to Know if a Somatic Tumor Mutation is Targetable" with Suanna Bruinooge, the director of research, strategy, and operations at ASCO's Center for Research and Analytics, or CENTRA, and Dr. Richard Schilsky, senior vice president and chief medical officer at ASCO.

Read the related article "Determining If a Somatic Tumor Mutation Is Targetable and Options for Accessing Targeted Therapies."

 

[DR. NATHAN PENNELL]

Welcome to the latest Journal of Oncology Practice Podcast brought to you by the ASCO Podcast Network, a collection of nine programs covering a range of educational and scientific content and offering enriching insight into the world of cancer care. You can find all recordings, including this one, at podcast.asco.org.

My name is Dr. Nate Pennell, medical oncologist at the Cleveland Clinic and consultant editor for the JOP. Today, I want to talk to you about an increasingly common scenario encountered in clinical practice. Molecular testing for biomarkers to help guide treatment of patients has now become a standard part of treatment for many types of cancer. For example, HER2 testing and breast cancer or EGFR mutation testing in lung cancer.

But testing is also increasing in other cancer types often using broad, multiplex assays surveying hundreds of genes. Clinicians are being presented with a report that may seem dauntingly complex and hard to interpret. And even when you have a drug recommended, that may be off-label for its use or even experimental, leaving patients and clinicians perplexed as to how to access them.

With me today to discuss these issues are Suanna Bruinooge, the director of research, strategy, and operations at ASCO's Center for Research and Analytics, or CENTRA, and Dr. Richard Schilsky, senior vice president and chief medical officer at ASCO.

We'll be discussing their paper, "How to Know if a Somatic Tumor Mutation is Targetable-- Options for Accessing Targeted Therapies" published in the August 2019 JOP. Welcome Suanna and Rich, and thanks for joining me today.

[DR. RICHARD SCHILSKY]

Thanks for having us, Nate.

[SUANNA BRUINOOGE]

Thanks.

[DR. NATHAN PENNELL]

So Rich, give me a little background on the problem that you were hoping to address with this paper. Why did ASCO feel it was important to provide a guidance to oncologists about interpreting testing reports and accessing these drugs?

[DR. RICHARD SCHILSKY]

Well, I think you actually framed the problem very well in your introduction. Obviously there's a lot of tumor genomic profiling that's going on these days, oftentimes for very good reason to identify actionable alterations that are known targets of effective anti-cancer therapies.

And what we've been seeing, of course, in more recent years is the more widespread use of genomic profiling, oftentimes for people who have advanced cancer, who no longer have any standard treatment options available. And the physician is looking to see whether or not there's something that might be considered actionable in the tumor genome that could provide a therapy option that wasn't considered.

We're also seeing that the testing itself has become much more expansive. So instead of testing for a few genes, many tests are now testing for hundreds of genes. And, of course, they can be many different alterations that could occur within any given gene. So the amount of information that's being provided to oncologists in these test reports is enormous and very difficult to interpret.
The nomenclature is difficult to understand. The biological relevance of the alterations is difficult to understand. And whether or not they really lead to a potential course of therapy is oftentimes difficult to figure out, because a lot of what turns up in the reports is difficult to understand and difficult to interpret.

So one of our goals in putting this short paper together was to try to provide resources to oncologists to help them navigate these test reports to help them have resources available to, in essence, look up the abnormalities that are being detected and try to figure out whether or not that's something that might be targetable with a particular drug. And then, of course, secondarily as you pointed out, to help walk them through the various strategies they can use to actually obtain the drug that seems like it might be a good choice for their patient.

[DR. NATHAN PENNELL]

So if I'm looking at one of these reports now and seeing these alterations, how do I decide if that truly is actionable or not? And how do we decide what level of actionability, whether this is something that's really a standard of care now or something that's much more lower level of evidence?

[DR. RICHARD SCHILSKY]

Yeah, it's a great question. So, I mean, there are actually some conventions regarding the level of evidence to assign to genomic alteration to determine its actionability. And in fact, ASCO working together with the College of American Pathologists and the Association of Molecular Pathology published a paper a couple of years ago, now, sort of assigning levels of evidence.

But the convention goes something like this-- if the alteration is the target of an FDA-approved drug, then that's a high level of evidence that the alteration is of clinical importance. It may or may not be of the same level of importance in a histology that is outside of the FDA-approved indication for the drug.

Best known example that is often described as BRAF mutations in patients with colorectal cancer, which do not respond nearly as well to BRAF inhibitors, as the same mutations respond when they occur in patients with melanoma. But nevertheless, a BRAF mutation occurring outside of the melanoma indication has still might be considered to be sort of level two evidence of potential actionability.
Then as you get further and further away from FDA-approved therapies or FDA-approved indications, then you get into lower levels of evidence. So you have, as you mentioned earlier, variants of unknown significance. These generally are alterations that are detected in the genome that truly are of unknown significance.
They have not been well-characterized. It's not clear what their biological relevance is with respect to being related to tumor initiation or progression. It's not clear whether they represent markers of response or resistance to therapy. They're just alterations where really more research is necessary to determine their actionability.

Nevertheless, I can tell you that we often find that many physicians think that it might be worthwhile to target APUS sort of just to give something a try. Then at the lowest level of actionability are the germline alterations. Now, even there, it's complicated because, of course, there are some germline alterations that actually direct you to use an FDA-approved drug, like germline BRCA mutations used to direct therapy with PARP inhibitors.

But generally speaking, germline alterations or alterations that have been well characterized and known to be functionally benign, there, the evidence for actionability would be considered to be very low.

[DR. NATHAN PENNELL]

I've certainly seen people treated with targeted drugs for variants of unknown significance and, otherwise, actionable genes, such as EGFR mutations but well outside the tyrosine kinase domain. And it really depends a lot on how well it's presented in these reports as to how easy it is to figure out what's actionable and what's not.

[DR. RICHARD SCHILSKY]

Well, that's right. And one of the reasons we included in the paper that quite expansive table of knowledge bases that are available is to help oncologists help participants who have elected a tumor board determine where to go to look up an alteration that might actually give them useful information as to, has it ever been reported before in human cancer?

If so, is it an alteration that is likely to be biological significance based upon the nature of the alteration and where it's located in the DNA? How close it is to other known ontogenic alterations and so on. So hopefully, readers of the article will find one or more of those knowledge bases' valuable resources, particularly in the context of a molecular tumor board discussion.

[DR. NATHAN PENNELL]

Absolutely. This is a fantastic resource. And I've got a couple of these bookmarked on my own desktop so that I can look things up, such as mycancergenome.org, for example. So I think our readers hopefully will check into that. So now that we have identified an actionable alteration, and we have a recommendation for a particular drug, what are our options for going about accessing these drugs for our patients?

[SUANNA BRUINOOGE]

Thanks, Nathan. This is a really good question. And I think we created a figure in the manuscript to really help clinicians and patients walk through what the options are laid out in front of them. And as you can see from the figure, it really does depend on the initial question being, does the targeted drug have FDA approval?
And as Dr. Schilsky mentioned earlier, it may depend on whether the indications specifically include the cancer type or histology that your patient has. But let's just say, then that case, it would be considered an on-label indication, and largely be reimbursed by insurers.

But let's say, the indication-- the cancer type is not specifically mentioned in the label. In that case, it would be considered an off-label indication. And so in that