SOBRE ESTE EPISÓDIO
Dr. Shaalan Beg and Dr. David Wang discuss key abstracts in GI cancers from the 2025 ASCO Gastrointestinal Cancers Symposium, including major advances in CRC, neoadjuvant approaches in esophageal cancer, and innovative studies on ctDNA.
TRANSCRIPT
Dr. Shaalan Beg: Hello and welcome to the ASCO Daily News Podcast. I'm Dr. Shaalan Beg. I'm a medical oncologist and an adjunct associate professor at UT Southwestern Medical Center in Dallas. Today, we're bringing you some key highlights from the 2025 ASCO Gastrointestinal Cancers Symposium, and I'm delighted to be joined by the chair of GI25, Dr. David Wang. Dr. Wang is a GI medical oncologist at the University of Michigan.
Our full disclosures are available in the transcript of this episode.
Dr. Wang, thanks for coming on the podcast today.
Dr. David Wang: Well, thank you. It's a pleasure to be here.
Dr. Shaalan Beg: GI25 featured major therapeutic advances across the spectrum of GI malignancies, and it was exciting to hear about innovations and novel approaches that are shaping the future of our field. Before we start talking about specific abstracts, could you share some of your key highlights from the meeting?
Dr. David Wang: Sure. Our theme this year was "Breaking Boundaries to Enhance Patient Centered Care." Past years' themes have focused more on precision oncology, but we wanted to broaden our focus on patients and to be more holistic, which kind of led us into some of the Intersection [sessions] that we had. Each day started with a different Intersection. The first one was "Emerging Therapies in GI Cancers", where invited speakers talked about bispecific antibody drug conjugates, theranostics, CAR T and other cell-based therapies. The second day was on "Personalized Risk Assessment for GI Cancers," and this included looking at polygenic risk scores for colorectal cancer, microRNAs and liquid biopsies such as exosomes and pancreatic cancer and non-endoscopic screening modalities in esophageal cancer. And on our final day, we wanted to talk about "Integrative Oncology and Integrative Medicine," looking at evidence-based uses of acupuncture and supplements in patients who are receiving treatment for cancer, mindfulness-based practices and exercise. And of course, we had a fantastic keynote talk by Dr. Pamela Kunz from the Yale School of Medicine titled, "Disrupting Gastrointestinal Oncology: Shattering Barriers with Inclusive Science." She highlighted the intersection of science, patient care, and health and gender equity. And I would encourage your podcast listeners to access the lecture in ASCO's Meeting Library if they haven't yet had a chance to hear Dr. Kunz's wonderful lecture.
We were really happy this year because the attendance hit a new record. We had over 5,000 people attend either in person or virtually from their home or office, and we had almost 1,000 abstracts submitted to the meeting, so these were either record or near record numbers. We offered a lot of different networking opportunities throughout the meeting, and attending found these to be incredibly rewarding and important and this will continue to be an area of emphasis in future meetings.
Dr. Shaalan Beg: Let's take a deeper dive into the exciting studies presented at GI25. The late breaking abstract LBA143 was CheckMate-8HW. This was the first results of NIVO + IPI versus NIVO monotherapy for MSI-high metastatic colorectal cancer. What are your thoughts about this study?
Dr. David Wang: Yeah, so we know that colorectal cancer patients with MSI-high tumors don't necessarily respond well to chemotherapy. And we were fortunate because last year CheckMate-8HW actually looked at two different arms – so this was NIVO + IPI compared to standard of care chemotherapy and showed its very significant improvement in median progression-free survival. And that was actually published in the New England Journal of Medicine back in November of 2024.
This year's presentation actually focused now on NIVO + IPI versus NIVO monotherapy. And as you know IPI+NIVO can be quite toxic. So this was an important analysis to be done. So we know that NIVO is definitely more easily tolerated. So what was interesting was that the 2-year and 3-year progression-free survival not surprisingly favored IPI+NIVO and this was statistically significant. And the overall response rate was also better with IPI+NIVO versus NIVO alone. I know we're always concerned about toxicities and there were higher grade 3 and 4 toxicity incidences in the combination arm versus the monotherapy arm, but overall, only about 28 additional events in several hundred patients treated. So I think that's well-tolerated. Our discussant Dr. Wells Messersmith actually said that, with this new data, he would consider doing combination immunotherapy in any patient that presented in the front line with MSI-high or deficient mismatch repair colorectal cancer that was metastatic.
Dr. Shaalan Beg: One of the focuses for directing first-line therapy for colorectal cancer has been right and left sided colon cancer because we know these are two different cancers with their own unique molecular subtypes. We heard on Abstract 17, the DEEPER trial, the final analysis of modified FOLFOXIRI plus cetuximab versus bevacizumab for RAS wild-type and left sided metastatic colorectal cancer. How do you summarize the findings of this study and what should our readers be aware of?
Dr. David Wang: Interestingly, this was a phase 2 study and the emphasis of the abstract was actually a subgroup analysis of those patients with RAS wild-type and BRAF wild-type as well as left sided cancers. So, I think the entire study enrolled 359 patients, but the analysis that was discussed at the meeting really focused on 178 patients that fit that characteristic. Very similar to what we've seen in prior studies, left-sided tumors have better response to cetuximab versus bevacizumab. And if you flip it so that you now are looking at right sided tumors, targeting EGFR is actually detrimental. The depth of response was better with cetuximab in these left sided RAS and BRAF mutant tumors. And so the lead author actually suggested that this could be a new first-line standard of care.
And the question is, is there a benefit of doing this triple agent regimen with modified FOLFIRINOX? We know there's a lot more toxicity with that. Not clear that there's a benefit for that over FOLFOX, maybe in younger patients that could tolerate it. When our discussant, again Dr. Wells Messersmith, spoke about this, he said that, in his practice he would, again, favor cetuximab over bevacizumab in combination with chemo, these left-sided RAS and BRAF wild-type tumors, but that he would actually prefer a doublet versus a triplet chemo regimen, and that is consistent with the current NCCN guidelines.
Dr. Shaalan Beg: Another area where colorectal cancer has been a wonderful model to study new technology has been in the area of circulating tumor DNA (ctDNA). And the BESPOKE CRC trial is looking to see if ctDNA can inform adjuvant treatment decisions for stage II and III colorectal cancer. And in Abstract 15, we heard final results of the BESPOKE CRC sub-cohort. What were the findings there?
Dr. David Wang: BESPOKE CRC is another one of these important ctDNA studies. It was an observational study, not a randomized trial, but it did provide a lot of different insights to us. We know that there were over 1,700 patients enrolled, and so it was reported that this is the largest ctDNA study in colorectal cancer performed in the United States. And they were able to analyze over 1,100 patients.
Some of the key findings were that postoperative adjuvant therapy management decisions actually changed in 1 out of 6 patients, so that's pretty significant. In terms of surveillance, we know that patients who have ctDNA positivity, this is prognostic of recurrence. In terms of patients who have positive ctDNA post-surgery, it looked like, at least in this observational study, the majority of patients who received any benefit were those who had positive ctDNA. So adjuvant therapy, even in stage II and stage III patients seemed to only benefit those patients who have positive ctDNA. I think that does raise the question, and this also was brought up in the discussion, which is "Can we de-escalate adjuvant therapy in terms of patients who are ctDNA-negative post-op?" And Dr. Richard Kim from Moffitt felt that we are not yet there. Obviously, we need randomized control trials where we are taking ctDNA results and then randomizing patients to receive adjuvant or non-adjuvant to really know the difference.
Other questions that come up with use of ctDNA include: What do you do with these patients who turn positive? This study for BESPOKE actually followed patients out to two years after surgery. So what you do with a positive ctDNA result wasn't really clear. It seems to suggest that once you turn positive, patients go on to more intensive surveillance. You know, again as an observation, patients who did turn positive were able to go to metastasis-directed therapy much more quickly. And again, this was supposedly to improve their curative intent therapy. And I think the other question that has been brought up all the time is, is this really cost effective? Patients want to know, and we want to give patients that information, but I think we're still stuck with what to do with a positive ctDNA level in a patient that's on surveillance because no randomized control studies have actually suggested that we need to start systemic therapy right away.
Dr. Shaalan Beg: Yeah. And I guess in terms of practice informing or practice changing, these results may not give us a clear answer. But because a lot of patients are asking for these tests, it does give us some real world experiences on what to expect in terms of conversion of these positive into negative and the outcome so we can have a shared decision making with our patients in the clinic and then come up with a determination on whether ctDNA for molecular residual disease is something which would be worthwhile for the care of our patient. But more to come, I guess, in coming years to answer different problems around this challenge.
Dr. David Wang: Yes, I agree.
Dr. Shaalan Beg: The BREAKWATER trial looked at the use of encorafenib, cetuximab and chemotherapy for BRAF V600E-mutant metastatic colorectal cancer. We've covered this combination for a second- third-line treatment in metastatic colorectal cancer previously. Abstract 16 from GI25 was evaluating the use of this regimen in the first-line space. Everyone was looking forward to these results, and what did the investigators present?
Dr. David Wang: I think this is, as you mentioned, a nice follow up to later lines of therapy where Dr. Kopetz from MD Anderson pioneered use of encorafenib, cetuximab and binimetinib in the BEACON trial. Everybody was kind of curious what would happen now if you use encorafenib plus cetuximab plus chemotherapy in the first-line setting. And so this is an interim analysis that was pre-planned in the phase 3 open label BREAKWATER trial. And even though there were three arms, and so the three arms were encorafenib plus cetuximab, encorafenib plus cetuximab plus FOLFOX, or standard of care chemo, only two arms were presented in the abstract. So basically looking at encorafenib plus cetuximab and FOLFOX-6 versus standard of care therapy, and the overall response rate was statistically significant with a 60.9% overall response rate encorafenib plus cetuximab plus chemo arm versus standard of care chemo was only 40%. The interim overall survival also was different. It was 92% versus 87% at 6 months and 79% versus 66% at 12 months, again favoring the chemotherapy plus encorafenib plus cetuximab. In terms of the statistics, the p was 0.0004. However, the pre-plan analysis required the p-value to be 1x10 to the -8. And so even though this looks really good, it hasn't quite met its pre-specified significance level. The good thing is that this is only interim analysis and the study is ongoing with future analysis planned.
So the real question is: Does it matter when we actually use this regimen? We know that the regimen's approved in the second third-line setting. What about in the first line? And there was some preclinical data that the discussant reviewed that shows that patients actually benefit if this is done in the first-line setting. For example, there was some preclinical data showing that even FOLFIRI, for example, can upregulate RAS, which would make tumors more resistant to this combination. This was thought to be practice-changing in a patient that has B600E showing up treatment naive that we should probably consider this regimen. And actually this did receive accelerated FDA approval about a month ago.
Dr. Shaalan Beg: Yeah, and for what it's worth, I put up a Twitter poll asking my Twitter followers on how the BREAKWATER trial results will change their approach for newly diagnosed BRAF mutated colorectal cancer. We got 112 responses; 72% said that they will incorporate encorafenib, cetuximab, FOLFOX for their frontline BRAF mutated patients. But 23% said that they would like to wait for overall survival results.
Dr. David Wang: Wow, that's interesting. They really want that 1x10 to the -8.
Dr. Shaalan Beg: I guess so. All right. Let's change gears and talk about esophageal cancer. LBA329 was the SCIENCE study which presented preliminary results from a randomized phase 3 trial comparing sintilimab and chemoradiotherapy plus sintilimab versus chemoradiotherapy for neoadjuvant resectable locally advanced squamous esophageal cancer. Where are we in this space?
Dr. David Wang: Okay. So, yeah, this was an interesting trial. Again, just to set the context, esophageal squamous cell carcinoma is more prevalent in Asia. And the study sites as well as the patients were mostly from Asia. So this was again a phase 3 trial with interim results. They only rolled 146 out of the planned 420 for this interim analysis. And yeah, they're using immune checkpoint inhibitor that we don't use in the United States, sintilimab, combined with their two standards of neoadjuvant therapy, either chemotherapy, which is more common in Asia, or or chemoradiation, which is more common in the US and Western Europe, versus chemoradiation. And so they actually had two primary endpoints, but only were reporting one. So their two primary endpoints were pathCR and the other one was event-free survival. The event-free survival, again, was not reported at the meeting.
What they found was that in terms of pathCR rate, if you take the two arms that are really informative about that, chemoradiation plus sintilimab versus chemoradiation alone, the pathCR rate was 60% versus 47%. We know that chemo alone doesn't induce as much of a pathCR rate, and that was 13%. So it was found that the delta in terms of pathCR between the chemoradiation arms, one with sintilimab and one without, was significant. And this actually confirms data again from Asia, like for the ESCORT-NEO trial where it used another immune checkpoint inhibitor pembrolizumab in addition to neoadjuvant chemo.
So as our discussant for this abstract said, yes, we know that radiation combined with chemotherapy improves pathCR rates, but we have recent data from the ESOPEC trial, we don't know that that necessarily will translate to overall survival. So again, waiting for additional enrollments and longer term follow up before incorporating this into clinical care here.
Dr. Shaalan Beg: So David, how do the results of the SCIENCE trial compare with our practice in the United States and ongoing studies asking questions for neoadjuvant therapy for esophageal carcinoma in the United States?
Dr. David Wang: I think obviously immune checkpoint inhibitor in the new adjuvant setting is important. Jennifer Eads at UPenn is running that EA2174 which is looking at chemoradiation plus or minus nivolumab, and then in non-pathCR responders randomized to adjuvant nivolumab per CheckMate 577 or nivolumab with intensification adding ipilimumab. We know that the ESOPEC trial just came out, and was published actually during the meeting, and that really focuses on adenocarcinomas. So adenocarcinomas of the GE junction, distal esophagus, now, we would probably treat very similarly to gastric using perioperative FLOT. However, the standard in the US for esophageal squamous cell carcinoma remains neoadjuvant chemoradiation. We know that squamous cell carcinomas are more exquisitely sensitive to radiotherapy. And then obviously in those patients who don't achieve a pathologic complete response, the expectation would be that they would go on to receive nivolumab per CheckMate 577. Again, the thought is that these tumors are more sensitive to immunotherapy given their higher incidences of mutational changes. And so again, this kind of goes along with the positive results seen in the SCIENCE trial that we just discussed with sintilimab but also EFFECT-neo with pembrolizumab. Obviously, we await the results of Jennifer's trial.
Dr. Shaalan Beg: And the last abstract I was hoping we could get your perspective on was Abstract 652, which is a Phase 3 study of everolimus plus lanreotide versus everolimus monotherapy for unresectable or recurrent gastroenteropancreatic neuroendocrine tumors, the STARTER-NET trial. What were the results of this study?
Dr. David Wang: So, I just want to give a shout out because we did have a session at this year's GI ASCO that looked at more rare tumors. So appendiceal tumors, neuroendocrine tumors, those kinds of things. So again, I would encourage your listeners to listen to that session if they have interest in that. Another type of rare tumor was adenosquamous tumors.
But in terms of the STARTER-NET trial, this was again an interim analysis of his phase 3trial and it was looking at combining everolimus plus lanreotide versus everolimus. So we know that in pancreatic-gastric neuroendocrine tumors, if you have low Ki-67, a well differentiated tumor, that the standard of care really is a somatostatin analog, and sometimes if they're more aggressive, we kind of consider molecular targeted therapy with everolimus. This was asking the question of whether we should do the combination on the frontline. And what was interesting is in this study, the patients were actually more of a poor prognostic set. So they had Ki-67 up to 20% or these were patients that actually had multiple liver lesions. And what they found was a median for progression free survival was improved with a combination out to 29.7 months versus 11.5 months with the somatostatin analog alone, and that the overall response rate was 23% versus 8.3%, again, favoring the combination.
If you looked at subgroup analysis, it was actually those patients who had Ki-67 greater than 10%, so the more aggressive tumors, or those with diffuse liver lesions that had the most benefit. So I think that would be the patient population I would consider this new combination with using would be those patients again with poorer prognosis neuroendocrine tumor phenotype.
Dr. Shaalan Beg: Thank you very much, Dr. Wang, for sharing your insights with us today and your great work to build a robust GI Cancers Symposium this year.
Dr. David Wang: Well, thank you. I mean that really is a cooperative effort. We appreciate all the members of the GI25 Program Committee as well as the ASCO staff that just made it an outstanding meeting.
Dr. Shaalan Beg: And thank you to all our listeners for your time today. You'll find links to the abstracts discussed today on the transcript of this episode.
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The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions.
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Disclosures:
Dr. Shaalan Beg:
Employment: Science 37
Consulting or Advisory Role: Ipsen, Array BioPharma, AstraZeneca/MedImmune, Cancer Commons, Legend Biotech, Foundation Medicine
Research Funding (Inst.): Bristol-Myers Squibb, AstraZeneca/MedImmune, Merck Serono, Five Prime Therapeutics, MedImmune, Genentech, Immunesensor, Tolero Pharmaceuticals
Dr. David Wang:
Honoraria: Novartis
Consulting or Advisory Role: Novartis, Cardinal Health, Bristol-Myers Squibb, BeiGene, Eisai
