Immunotherapy Beyond First Line Therapy for Advanced Gastroesophageal Adenocarcinoma?

Dr. Manish Shah discusses the first ASCO guideline for advanced gastroesophageal cancer. He addresses biomarker testing to help guide therapy - including HER2 testing, mismatch repair testing, and assessment of PD-L1 expression. Dr. Shah then reviews the evidence-based recommendations from the ASCO Expert Panel, including first-line therapies for esophageal, gastroesophageal junction (GEJ), and gastric adenocarcinoma, along with esophageal squamous cell carcinoma, based on these biomarker results, as well as evidence in the second-line setting – and beyond – and how to provide optimal care for these patients.

Read the full guideline, "Immunotherapy and Targeted Therapy for Advanced Gastroesophageal Cancer: ASCO Guideline" at www.asco.org/gastrointestinal-cancer-guidelines

TRANSCRIPT

Brittany Harvey: Hello, and welcome to the ASCO Guidelines podcast series, 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 the shows, including this one, at: asco.org/podcasts.

My name is Brittany Harvey, and today, I'm interviewing Dr. Manish Shah, from Weill Cornell Medicine, in New York, New York, lead author on 'Immunotherapy and Targeted Therapy for Advanced Gastroesophageal Cancer: ASCO Guideline’.

Thank you for being here, Dr. Shah.

Dr. Manish Shah: Thank you for having me. It's great to be here, and I'm looking forward to our interview.

Brittany Harvey: Great. And first, I'd like to note that ASCO takes great care in the development of its guidelines, and ensuring that the ASCO Conflict of Interest policy is followed for each guideline. The full Conflict of Interest information for this guideline panel is available online, with the publication of the guideline in the Journal of Clinical Oncology.

Dr. Shah, do you have any relevant disclosures that are directly related to this guideline topic?

Dr. Manish Shah: Yeah. So, I've received research funding from Merck, as well as from Bristol Myers Squibb, as well as from Oncolys Pharma. These are all companies that have worked for immunotherapy and upper GI cancers.

Brittany Harvey: Okay, thank you for those disclosures.

Then diving into the content here, what is the scope and purpose of this first ASCO guideline for advanced gastroesophageal cancer?

Dr. Manish Shah: Thank you. As you point out in the question, this is the first guideline for advanced gastroesophageal cancer, and really it is a very timely guideline because the landscape for the management of upper GI cancers has evolved and changed dramatically in the last several years. For a long time, we were really focused on chemotherapy for esophagus and gastric cancer. We, in fact, treated squamous cell cancer of the esophagus very similar to adenocarcinoma of the esophagus. And even though we knew of the different disease subtypes for gastric cancer, they didn't really play a role in differentiating management.

About 10 years ago, trastuzumab was approved for the treatment of HER2-positive gastric cancer, but since then, we've had really a run of significant positive studies that have informed practice, and we felt that this was really a timely guideline to help us with regard to our patients with upper GI cancer, particularly, with metastatic disease who need first-line, and beyond therapy.

Brittany Harvey: Excellent. Then you've just mentioned that the management of these upper GI cancers has evolved, so I'd like to review the key recommendations of this guideline that you just gave an overview of. So, starting with first-line therapy - is immunotherapy, or targeted therapy in combination with chemotherapy, recommended as first-line treatment for advanced gastroesophageal adenocarcinoma or squamous cell carcinoma? And what are these recommendations by the subgroups of patients by HER2 status or PD-L1 protein expression?

Dr. Manish Shah: The answer to that is that, in fact, it is now recommended for most patients, but I think I might start a little bit one step behind. So, with a newly diagnosed patient with an upper GI cancer, I think the first step in the management is to test for the biomarkers that will help guide therapy. So, for esophageal adenocarcinoma gastroesophageal junction, and gastric cancer, which is almost always adenocarcinoma, we recommend that everybody undergo HER2 testing immunohistochemistry, as well as a mismatch repair testing or MSI-high; either way you get it is fine, as well as an assessment of the PD-L1 expression, which is scored according to the Combined Positive Score or CPS.

So, that panel of biomarkers will help guide the management for the adenocarcinomas. And so, if you are HER2-positive, then we've known for a long time that the standard of practice would be chemotherapy with trastuzumab; typically, it's a platinum and 5-FU-based treatment with trastuzumab. Most recently, and this is in the guideline and the second part of your question, if you're HER2-positive, and you actually now are recommended to do chemotherapy with trastuzumab and pembrolizumab, which is a PD-1 inhibitor. Then that's based on the KEYNOTE-811 study, that we have the first analysis, which is a response rate analysis, and the response rate improves significantly with the addition of the immunotherapy.

But for the majority of patients who are HER2-negative, we do look at the PD-L1 status by CPS, then here it's a little bit trickier. The FDA guidance is to recommend immunotherapy with chemotherapy for all patients in the first-line setting. However, we also recognize that the higher the PD-L1 expression, the more likely the benefit from immunotherapy. And several studies have demonstrated that, and we've shown that in the guideline as well.

And there seems to be a very reasonable cutoff of a CPS score of five or higher, and above that, there really is clear benefit of the addition of immunotherapy, specifically, nivolumab to chemotherapy for gastroesophageal cancer, that's based on CheckMate 649. And then for esophageal adenocarcinoma, the additional recommendation is the addition of chemotherapy with pembrolizumab for a CPS of 10 or higher. And I think for CPS zero, most of us really felt pretty strongly that there was really no role for the use of immunotherapy because remember, these drugs do have some side effects, that although rare, can be really debilitating.

And then, there's an intermediate category of CPS, 1-4, and here, I think you have to use a little bit of a judgment call. We didn't recommend it in general but did suggest that that would be more of an individual-use basis. And the judgment call is that if the CPS is four, if you showed the slides to another pathologist, it's very possible it could have been a five. So, that kind of heterogeneity is something that we might consider to go ahead and use the immunotherapy.

But if the CPS is lower, the context is also questionable. We talked a little bit about the side effects of immunotherapy. If someone really has bad rheumatoid arthritis, we've all actually had patients given immunotherapy, they come in debilitated. So there, we really would want to be sure that the CPS is high, so that way, the patient is deriving the benefit, and we then adjust the rheumatoid arthritis medicines accordingly.

So, I think the other theme through our guideline is that with more options, we are able to actually provide more personalized care to our patients, giving them the best opportunity to receive the care with minimizing toxicity and maximizing benefit. So, that was a long-winded answer to the question that we do recommend immunotherapy in the first-line setting, in the right context, and for HER2-positive tumors, we recommend trastuzumab plus immunotherapy in the first-line setting, in the right context.

And then, the final thing was the mismatch repair status. So, unlike colon cancer where there's level one evidence comparing immunotherapy to first-line chemotherapy, we don't have that in upper GI cancers. So, we do recommend it, but as for the guidance, it would be in the second-line setting, or later.

Brittany Harvey: Great. Those are key clinical considerations that you just reviewed, and I appreciate you talking through both the evidence, and then the discussions that the panel had on the benefits of therapy, and also the adverse effects that can affect patients.

So, then, beyond first-line therapy for later-line therapies, is immunotherapy or targeted therapy recommended as second-line or third-line treatment for advanced gastroesophageal adenocarcinoma?

Dr. Manish Shah: Yeah. This is a great question, and I think it can be a point of confusion. So, for a long time, immunotherapy, specifically pembrolizumab, was approved and indicated in the third-line setting for CPS 1 or higher patients. The FDA actually removed that approval, and so it's no longer indicated in that setting. And most patients will have gotten immunotherapy in the first-line setting, and as of now, there's no data that suggests that continuing immunotherapy or rechallenging with immunotherapy would be of any benefit.

So, in general, the answer is that we would not use immunotherapy beyond first line. I guess the one caveat is if your CPS is low and you didn't receive immunotherapy in the first-line setting, but you happen to be MSI-high, then certainly, that would be an indication to use immunotherapy in that setting. But I think that would be a pretty rare event. So, if you use immunotherapy in the first-line setting, then there's really no role for continuing or re-challenging with immunotherapy in the second or later-line settings. But that's an active area of drug development, and we think that there will be an opportunity in the next few years for combination strategies to salvage people who had immunotherapy in the first-line setting.

So, in terms of second line and beyond, the other area that we should talk about is in squamous cell cancer. So, squamous cell cancer is a little bit unique, of the esophagus. It is more sensitive to immunotherapy than adenocarcinoma, and in fact, the guidance is to use immunotherapy, either with chemotherapy or as a doublet nivolumab and ipilimumab, in the first-line setting for most patients with squamous cell cancer. If, however, immunotherapy wasn't used in the first-line setting for squamous cell cancer, it is indicated in the second-line setting as nivolumab monotherapy. So, that would be one distinction between the squamous esophageal cancer and adenocarcinoma of the upper GI tract.

Brittany Harvey: Great. I appreciate you reviewing those considerations for later-line therapies, and we'll look forward to more research in this area in the future, as you just described.

Thank you for reviewing all of those recommendations. In your view, what is the importance of this guideline, and how will it impact clinical practice?

Dr. Manish Shah: So, this is an important guideline, because as we've talked earlier, there are lots and lots of options for patients, and we think that the guideline will help frame the discussion on how to best manage our patients in the first line, second line, and beyond.

I think it also frames where there are holes in our knowledge. These knowledge gaps are opportunities for research, for us to continue to develop therapies in gastroesophageal cancers.

Brittany Harvey: So, that's excellent. And you just mentioned that there's more options for patients with advanced upper GI cancers. So, finally, Dr. Shah, how will these guideline recommendations affect patients with advanced gastroesophageal cancer?

Dr. Manish Shah: Yeah. I hope that it will give patients and their physicians a strategy for how to treat patients in the first-line and beyond setting. Gastroesophageal cancer treatment has evolved significantly. Not too long ago, there was a debate of whether or not chemotherapy had a benefit in the first-line setting, or in the second-line setting, and there are randomized studies that demonstrate that for sure. Now, we're in an era where people should get chemotherapy, and then in the right context, get additional targeted agents, like immunotherapy or HER2-targeted therapy.

And if we can treat patients along the continuum of their care, thinking about first line, second line, third line, much as we do for colon cancer, we think that more patients will be able to get access to more of the drugs that are available, and in the long run, that will ultimately help more patients, and give patients better outcomes. I hope this guideline will achieve that goal for our community.

Brittany Harvey: Absolutely. And I appreciate you providing the details and the context for this new guideline. Thank you so much, for all of your work to develop these evidence-based recommendations. And thank you for your time today, Dr. Shah.

Dr. Manish Shah: Oh, absolutely. Thanks so much for having me, and I'm happy to come back anytime.

Brittany Harvey: And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast series.

To read the full guideline, go to: www.asco.org/gastrointestinal-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, available on iTunes or the Google Play Store.

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