Germline EGFR Mutations and Familial Lung Cancer

Journal of Clinical Oncology (JCO) Podcast

Dr. Shannon Westin and her guests, Dr. Judy Garber and Dr. Geoffrey Oxnard, discuss the paper "Germline EGFR Mutations and Familial Lung Cancer" recently published in the JCO.

TRANCRIPT

The guest on this podcast episode has no disclosures to declare.

Shannon Westin: Hello, and welcome to JCO After Hours, the podcast where we get in-depth on articles that are published in the Journal of Clinical Oncology. I am your host, Shannon Westin, Social Media Editor for the JCO and Gynecologic Oncologist by trade. And it is my great pleasure to speak today with you about an amazing manuscript entitled, “Germline EGFR Mutations and Familial Lung Cancer.” It was published in the JCO on August 14, 2023.

The authors have no conflicts of interest, and they are Dr. Geoffrey Oxnard, he's a Thoracic Oncologist and Associate Professor, Hematology and Medical Oncology at Boston Medical Center.

Welcome, Geoff.

Dr. Geoffrey Oxnard: Hi, Shannon. Thanks.

Shannon Westin: And Dr. Judy Garber, the chief of the Division of Cancer Genetics and prevention at the Dana-Farber Cancer institute in Boston. Welcome, Judy.

Dr. Judy Garber: Thank you. Hi, Shannon. Hi, Geoff.

Shannon Westin: So excited you both could be here. Let's get started. So first I just want to levelset for our audience. Can you speak just a little briefly about the incidence and mortality of lung cancer and how that's been changing over time?

Dr. Geoffrey Oxnard: Sure. Lung cancer is common and it's deadly, more than 200,000 cases a year in the United States, more than 100,000 deaths a year in the United States. But I think importantly, it's evolving. Its biology is evolving as smoking incidence goes down. We've identified these genomic subtypes of lung cancer that are sort of increasingly apparent and important as we think about its treatment. Outcomes are changing with emerging therapies, presentation is changing with lung cancer screening and with a growing ability to now find cancers early and prevent them. And so it's in that setting of a very dynamic disease that we chose to study a really unique little slice of it, which is germline risk.

Shannon Westin: So let's take that one step further because I think that's really interesting. You mentioned the genomic aberrations and kind of how you're using that to target. Can you expand upon that a little bit more for me?

Dr. Geoffrey Oxnard: Lung cancer that I've long studied is different than breast cancer when Judy has long studied because we think about its somatic alterations, we've always thought about KRAS mutations, EGFR mutations, and smaller and smaller splice limit. ALK, RAS, RET HER2, etc. And so tumor testing in lung cancer has one of the first to be standard across on solid tumor oncology. And the germline genetics was kind of an afterthought and is the flip, I think, of how genetic testing evolved in the breast cancer space for example.

Dr. Judy Garber: I might argue a little bit if breast cancer was earlier and it was subtyped some molecularly it doesn't have as many molecular subtypes yet perhaps as lung cancer. But we've all been studying the somatic space to look for targets for therapy. And the germline space, certainly in breast cancer, came much earlier. And everybody knows about BRCA1 and 2. Now, we hope everybody knows about Lynch Syndrome, but certainly not everybody's thinking about inherited lung cancer risk.

Dr. Geoffrey Oxnard: Yeah, these have converged. I think 10 years ago when this kicked off, I felt like a super outlier for thinking about, wait a second, what about the genetics behind all this that is leading to this strange variable presentation of lung cancer? For example, we know that in Asian populations, one type of lung cancer, EGFR mutant lung cancer, is more common. There must be some geneticness that leads to that. What explains the sort of pattern of presentation of these genetic subtypes in the populations we see in the US, that’s pretty unclear?

Dr. Judy Garber: So, I think, Shannon one of the clues about all this came from the fact that the EGFR mutations were being identified in the tumors. And then I really should let Geoff tell this story, but as the amateur thoracic person in the room here, to me, it was so interesting that there were the EGFR mutations, then there was treatment exploiting EGFR mutations, and the most common resistance mutation was this T790M variant. But when labs started testing EGFR, there was a small group of people who had that resistance variant without ever having been treated at all. So that was the obvious question, what was it doing there? And that's where Geoffrey came in.

Dr. Geoffrey Oxnard: Yeah, this is a patient I met more than a decade ago at my fellowship in MSKCC. She'd been living with a T790M mutation in her tumor for years and years and years. I was like, “Well, I don't understand. Why is this sitting there?” And she had this sort of slightly mysterious history of lung cancer in her family. And we realized, wait a second, this T790M was behind her cancer from the beginning, and in fact, might have been the basis of why she developed lung cancer. And so that actually motivated a career development award I submitted to the Conquer Cancer Foundation of ASCO, a grant I received, and that then led to a program that I led at Dana-Farber under Judy's mentorship, where over the past decade, we sort of focused in and studied this strange, rare syndrome, really to dig into inheritedness as a kind of different flavor of lung cancer genetics.

Dr. Judy Garber: Well, and now it's really a good time to think about this because we're recognizing there are younger cancers, colon cancer, like an epidemic, and lung cancers, and we're not sure how many of them are genetic or come from other exposures. Geoff talked about the differences in Asia, some of which are certainly genetic, some which may be environmental, especially in the lung, where that's such an issue. But trying to sort these things out, you have to be willing to think a little bit differently. And that was fun when Geoff came from the lung program, interested in the germline, we said, “Oh, we have to do this.”

Shannon Westin: Well, let's talk about what you did. I would love to hear and I know the audience would as well about the design of this study, so called INHERIT study. Very good name. I love a good name. This is a good one.

Dr. Geoffrey Oxnard: Yeah. So that stands for Investigating Hereditary Risk of T790M, INHERIT. I forget where we coined that. Let me give you a case example. A patient presents in his 40s. I remember this man. He has an EGFR mutation in his tumor. He has a T790M in his tumor as well. He had routine tumor testing that lung cancer patients were getting. And he says, “Oh, also, my brother had lung cancer in his 40s just a couple of years ago. He was a smoker, though. He never had genetic testing.” And so this patient we test on the study, we hypothesized that when patients present with T790M at diagnosis, that it would be a representation of an underlying germline EGFR mutation. Our hypothesis was that about 50% of the time T790M at diagnosis would be explained by a germline behind the doll. And that that could then empower families like this one to understand the kinds of lung cancer they're getting in their family, the kinds of treatment they should be getting, and the kinds of testing they should be getting to look for lung cancer at risk early on.

It really saddens me that in a family that doesn't know about this condition, the brother would never get testing and would never think that I might be getting or might never get testing, might not be disposed to getting testing, and might not realize there's a therapy available to target that EGFR mutation if he died young without even much treatment. But this individual, we tested his lung cancer, we found him a therapy, we put him on a pill therapy that could last a very long time. And so we set up a program with a consortium alchemy, the Addario Lung Cancer Medical Institute, where we enrolled at three sites, both at Dana-Farber in Boston, Vanderbilt, and Ohio State, with some motivated investigators there that we appreciate their collaboration.

But also, again, this is now more than 10 years ago, set up shop where people could enroll remotely, that if you found a T790M in your tumor, for whatever reason, you could reach out to the team at Dana-Farber centrally and get consented online and even get counseling. And this is one of the early ways of getting this remote participation. And you can imagine, over the course of the study, we quickly ran out of individuals at any given site, but that remote enrollment accelerated and really allowed us to get to the large population of remote study.

Dr. Judy Garber: We were lucky that things were happening. The things you don’t expect. So EGFR testing was not routine at that time. And the EGFR testing that had developed in Dana-Farber and NGH became standard of care at Dana-Farber so we were finding those patients, and then grew outside as well, at institutions and testing labs. And these people would somehow emerge so we were very lucky that we were able to set up remote testing. We could send and get a saliva sample and be able to test. Or these were people who got tested through their own doctors, found out they had this mutation and then went online and said, “Who knows anything about this?”

I would say that we and our amazing genetic counselors who spoke to all these patients, took their detailed family histories, got their other information, and were able then to really build out these cohorts so we can understand them. And to look at, for example, Geoff’s question, it was really his question, “Why did we have such clusters in certain parts of the country? Could it be that there were the so-called founder mutations that somebody had this mutation and they spread their genes around so that they’re around the country and that turned out to be true.

Shannon Westin: It's so fascinating, and I love how you kind of almost crowdsourced getting these patients to you because I was mystified because it's such a rare aberration and you had so many patients. Let's talk a little bit maybe about your patient population and who volunteered, and is it reflective of kind of you do think, the general population?

Dr. Geoffrey Oxnard: I want to give a shout out to the GO2 Lung Cancer Foundation. That really was a lot of the ‘rah rah’, getting people to know about this, having some word of mouth and spreading the word. And so certainly there are physicians around the country that have been like found patients that I've got to know because they sent us patients to study over the years. We ended up getting germline testing on 141 individuals who presented eligible for testing because of either a relative or a mutation that was suspicious for inherited. Most of those were enrolled remotely, in the end, as you might expect. We found what you might expect, that this was Mendelian in its inheritance, that if you had a first degree relatives, they had 50% chance of having this. And so we sort of slowly built these pedigrees of individuals who once they were positive, would refer in their relatives and say, “Please go get testing. Let's describe our family and help understand our risk.”

It ended up boiling down to six individuals with a germline EGFR mutation from 39 different families. I remember one family where two different cousins presented separately to the program, not knowing each other was participating. And so, of course, there's not that many of these families around the United states, but we're really very lucky to have touched so many different individuals. What did we find? That if you had a germline EGFR mutation, your tumor almost always had an EGFR mutation. That really is the dominant biology of lung cancer that presents in these affected individuals, that it presents young, that the likelihood of developing lung cancer is around 55% by age 40 to 50. So it really is– I'm trying to make sure I'm quoting that right, actually, Shannon, I'm looking at the numbers here, but it was a really broad range of diagnosis.

We had a 28-year-old who was affected and an 83-year-old who was affected. I saw a family where the grandson had lung cancer, but his father and grandfather who had germline EGFR mutations, did not. So variable penetrance. Judy, of course, told me, “Geoff, this is the way families present. Come on, Geoff.” But other families, incredible penetrance– not everyone having lung cancer, many of them smoking, some of them not smoking. But for these families, what a sense of empowerment to say, “Oh, this helps explain what's going on in our family, why this is happening at a younger age.” And helps explain the therapies that we had some concern about giving these potent EGFR inhibitors originally, understanding every cell in their body has this EGFR mutation. Are we going to somehow cause toxicity? No. These potent therapies can be effective, can be tolerated, and can work for many years. So we really feel hopeful that we've described a syndrome that's out there that people see and that has a distinct presentation, a distinct treatment pattern, and a clear association with lung cancer risk.

Dr. Judy Garber: And I think that now the opportunity is to say, can you find these people before they get their lung cancers? Some of them have abnormalities on scans. Think of it's like the APC, the polyposis coli of lung cancer. You can see these adenomas forming, but we can't really predict exactly who's going to develop tumor when. And that, I think, is a challenge that families have to help us with because we need to continue to identify some of these people who have not had cancer. They have children. They want to know what to tell them besides not smoking adamantly and maybe with some hopes that we're going to do some screening.

I am afraid there probably is not good data that EGFR inhibitors could be used for prevention, but it's tempting to think that way. So there's plenty of work to do still to sort out the questions. This is the nature of genetics. We often find inherited susceptibility and people want to know, “Well, why would I want to know? What am I going to do about it?” And here I would say, “We're going to figure out what's your risk more specifically, and how can we help reduce that risk, in addition to telling you not to smoke.”

Dr. Geoffrey Oxnard: I do want to allude to Judy's comment about founder effect. I didn't tell you exactly about the presentation, but these families, first off, we only found germline EGFR mutations in Caucasian individuals and in black individuals, and it was mostly in the United States and in fact, enriched in the southeast United States. And don't get me wrong, we had enthusiastic participation from Vanderbilt. But still it seemed like there was more southeast United States prevalence. And even families I met in the Boston area would say, ‘Oh yeah, I have relatives going back to Arkansas.”

And so we ended up with a bit of a suspicion for this geographic enrichment, studying the genomes of these affected individuals, and in fact did find a very large region of chromosome 7 that was shared in more than 90% of the folks we tested, suggesting a founder effect in the southeast United States, probably white and black. And that goes back hundreds of years, maybe 200, 300, 400 years, as far as we can estimate, making me think that this is a fairly unique syndrome that we're seeing in North America, but actually may not be prevalent in other parts of the globe. Though we did identify a single individual in Australia, it might be a unique phenomenon in North America.

Dr. Judy Garber: At least more common. But these days, people travel, so hard to know.

Shannon Westin: I don't know if you've gotten a chance to do this - any other cancer type seeming to be associated with this mutation?

Dr. Judy Garber: No, fortunately not.

Shannon Westin: Okay, very interesting. And what about outcome? What was the association, or was there any association of these mutations with cancer related outcomes?

Dr. Geoffrey Oxnard: I would say the survival of these cancers isn't that different than EGFR mutant lung cancers. If they get to effective therapy, they can live for years on therapy. If they don't, they can do quite poorly. One interesting finding is that they can present in a multinodular fashion that might be multiple primaries. And so you can kind of use an approach of eliminating individual clones. Sometimes it's been described these different tumors have different mutations, and so you might treat them like a stage IV lung cancer, but actually they lived for a long time because actually they had multiple stage I lung cancers, so it can present a little bit differently. And then we tried to collect CT scans on affected carriers who did not yet have lung cancer to see if they might develop lung cancer. It was not required on study, and it's sort of an area of future investigation. But as you can imagine, lots of lung nodules and certainly anecdotes of individuals where we found early precancers through the screening effort, motivating the investigation that Judy was alluding to.

Dr. Judy Garber: I think this is what you expect in inherited predisposition that you have an earlier chance. So some of them are younger, not the 84-year-old, but that they could be younger, that they could have multifocal disease, that their biology could be different, but could be the same, maybe accelerated, maybe not. Some of these are slower. And I think that's why we're excited to be able to continue this work with the group at Dana-Farber.

Now, Jaclyn LoPiccolo is going to lead the INHERIT study, but much of the team is the same. And now the focus will be even more on trying to really quantify the risk and help think about prevention strategies and screening for these patients. It's a little tricky to want to do too much chest CT screening. On the other hand, there are lower dose CTs now, and we hope the guidelines will clarify the role of inherited risk. At ASCO this year there were a lot of talks about inherited lung cancer risk, but nothing is quite as well characterized as, I think, the T790M population.

Shannon Westin: Well, thank you all so much. This was fascinating. I learned a ton and I know our listeners did as well. And thank you to our listeners. This was “Germline EGFR Mutations and Familial Lung Cancer.” Again, published in the JCO August 14, 2023. So go check it out and check out our other podcasts on the website or wherever you get your podcasts. Have an awesome day.

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