Dr. Shaalan Beg highlights practice-changing studies in GI cancers featured at the 2024 ASCO Annual Meeting, including the ESOPEC trial in esophageal adenocarcinoma and durable responses to PD-1 blockade alone in mismatch repair-deficient locally advanced rectal cancer.

TRANSCRIPT

Geraldine Carroll: Welcome to the ASCO Daily News Podcast. I'm Geraldine Carroll, a reporter for the ASCO Daily News. My guest today is Dr. Shaalan Beg, an adjunct associate professor at UT Southwestern Simmons Comprehensive Cancer Center. Dr. Beg will be discussing practice- changing abstracts and other key advances in GI oncology that were presented at the 2024 ASCO Annual Meeting. His full disclosures are available in the transcript of this episode. 

Dr. Beg, thanks for being on the podcast today. 

Dr. Shaalan Beg: Thank you for having me.

Geraldine Carroll: Let's begin with LBA1, the ESOPEC trial. This was featured in the Plenary Session, and this study compared two treatment strategies for locally advanced esophageal adenocarcinoma that could be treated with surgery. The strategies include the CROSS protocol, which consisted of chemoradiotherapy before surgery, and the FLOT protocol of chemotherapy before and after surgery. Can you tell us about this practice-changing study, Dr. Beg?

Dr. Shaalan Beg: Yes. According to this study, perioperative chemotherapy with FLOT was better than neoadjuvant therapy with chemoradiation and carbo-taxol for people with adenocarcinoma of the esophagus. There were 438 patients enrolled on this phase 3 study. R0 resection rates were fairly similar across both groups. The PCR rates were a little higher on the FLOT group. But when you look at the median overall survival difference, 66 months in the FLOT group versus 37 months in the CROSS group, 3-year survival was 57% versus 50% favoring FLOT therapy as well. 

So a couple of caveats on this clinical trial, because the first thing to note is that the standard treatment for this disease has evolved because we now don't only give CROSS chemoradiation, we also give immunotherapy after the completion of chemoradiation for this group of patients. And in this study, since it predated that standard of care, patients did not receive immunotherapy. But having said that, the take home for me here is that chemotherapy is better than chemoradiation for this group of patients, recognizing the fact that 1) they only enrolled adenocarcinoma patients, and 2) patients with high T stage were not included. So the folks with high T stage would be those who we would expect would benefit from the radiation aspect. So my take home here is that more chemotherapy is better in the perioperative space. Radiation should be considered for individuals who need more local control. But in general, I think we're going to see us moving more towards chemotherapy-based regimens with FLOT for this group of patients.

Geraldine Carroll: Great. So moving on to rectal cancer, in LBA3512, investigators reported durable, complete responses to PD-1 blockade alone in mismatch repair deficient locally advanced rectal cancer. Can you tell us more about the promising durable responses that occurred in this trial? 

Dr. Shaalan Beg: On first glance, seeing that immunotherapy has good activity in patients with mismatched repair deficient rectal cancer isn't really headline breaking news anymore. We've known about this activity for this group of patients for many years. Earlier at ASCO, the investigators presented early results of this compound for people receiving six months of dostarlimab therapy for people with mismatched repair deficient, locally advanced rectal cancer, and showed that they had a very high complete response rate. At that time, it generated a lot of interest and there was a lot of curiosity on whether these outcomes will be sustained. We don't know other characteristics of their biologic status and whether this was some sort of reflection of the patients who are selected or not.  

So here in this presentation at ASCO 2024, they did come back to present follow-up data for people with mismatch repair deficient colorectal cancer, having received 6 months of dostarlimab. Forty-seven patients had been enrolled, and the 41 patients who had achieved a clinical complete response continued to have disease control with no distant metastases. So that's very compelling information. There were no additional serious adverse events greater than grade 2 that they saw, and they did follow circulating tumor DNA, and those did normalize even before they had their colonoscopy to examine their tumors. 

So, again, we're continuing to see very encouraging data of immunotherapy, and the response rate with dostarlimab seems to be very interesting for this disease, and it will be interesting to see how this pans out in larger studies and how this translates into the use of dostarlimab across other diseases where other checkpoint inhibitors are currently being used.

Geraldine Carroll: Absolutely. So, moving on to LBA3501. The COLLISION trial looked at surgery versus thermal ablation for small cell colorectal liver metastases. This was an international, multicenter, phase 3, randomized, controlled trial. How will this study change clinical practice? 

Dr. Shaalan Beg: Kudos to the investigators here. They looked to understand the difference in outcome in treating people with colorectal cancer with liver only metastases. These clinical trials are extremely difficult to design. They're very difficult to enroll on because of the multidisciplinary aspect of the interventions and patient and provider biases as well. So on this clinical trial, the investigators enrolled people with resectable colorectal cancer, liver metastases so they did not have any metastases outside the liver. Patients were required to have 10 or less known metastases that were less than 3 cm in size. There were other allowances for larger tumors as well. And after an expert panel review, patients were randomized to either resection or ablation. It was up to the physicians whether they performed these laparoscopically or openly or percutaneously, depending on the biology of the patient and the anatomical presentation. 

There was a predefined stopping rule at the half-time for this clinical trial, which showed a benefit in the experimental arm of ablation compared to standard of care. The overall survival was not compromised. Progression-free survival was not compromised with local therapy. But there were differences in morbidity and mortality, as we would expect, one being a surgical procedure and the other being ablation, where, according to this study, of the 140 or so patients who received either treatment, 2.1% of people who underwent resection died within 90 days of surgery. The AE rate was 56% in the resection sample compared to 19% in ablation, and the 90-day mortality for ablation was 0.7%. So less morbidity, improved mortality, reduced adverse events with ablation versus surgical resection without compromising local control and overall survival.  

And I think for practice here in the United States, this does provide very interesting data for us to take back to the clinic for lesions that are relatively small and could generally be addressed by both surgery and ablation. Historically, there are various non biologic factors that could go into deciding whether someone should have surgery or ablation, and it could be based on who the physician is, who's seeing the patient, what the practice patterns in a specific organization are, and where their expertise lie. But here we're seeing that ablation for the small lesions is a very effective tool with very good local control rates, and again, in this selected group of patients with liver only metastases. And I think it is going to make tumor board discussions very interesting with data backing ablation for these lesions.

Geraldine Carroll: Well, let's move onto the MOUNTAINER study. This study created some buzz in the colorectal cancer space. That's Abstract 3509. Can you tell us about the final results of this phase 2 study of tucatinib and trastuzumab in HER2-positive metastatic CRC? What are your thoughts on this treatment option, which seems to be well tolerated?

Dr. Shaalan Beg: So, HER2 overexpression or amplification occurs in about 3 to 5% of patients with metastatic colorectal cancer and up to 10% of people who have a RAS/RAF wild type disease. On the previous episodes of the podcast we have covered precision targeted therapy in colorectal cancer, focusing on c-MET, focusing on BRAF, and here we have updated results targeting HER2 for colorectal cancer. And the results of the MOUNTAINEER study have been out for a while. This is a phase 2 study looking at combining tucatinib which is a highly selective HER2 directed TKI with trastuzumab, the monoclonal antibody for HER2 targeting. And what they found on this study is the confirmed overall response rate was 38%. Duration of response was 12 months, overall survival was 24 months and these are the results that have been already released and now we have an additional 16 months of follow up and these results continue to hold on. PFS and overall survival gains were held, which makes it a very interesting option for people with colorectal cancer. You mentioned the tolerability aspect and side effects. I think it's important to know the spectrum of side effects for this disease may be a little different than other TKIs. There's hypertension, but there's also the risk of diarrhea, back pain and pyrexia, with the most common grade 3 treatment related adverse event was an increase in AST level seen in 10% of people of grade 3 and above. 

So where does that really leave us? There is a confirmatory randomized first-line trial of tucatinib and trastuzumab in the first line setting, which is currently ongoing. So we'll stay tuned to see where that leads us. And with the HER2 space right now for colorectal cancer with the development of antibody drug conjugates, we may have more than one option for this group of patients once those trials read out.

Geraldine Carroll: Excellent. Well, moving on to LBA4008, that's the CheckMate-9DW trial. This trial reported first results looking at nivolumab plus ipilimumab versus sorafenib or lenvatinib as first-line treatment for advanced hepatocellular carcinoma. Can you tell us about this trial? Will there be a potential new standard of care in advanced HCC?

Dr. Shaalan Beg: When we think about patients with advanced HCC, the only treatment option that they had for about a decade and a half were just oral track tyrosine kinase inhibitors that had modest to moderate clinical activity. Since then, we've seen that combination therapy is better than TKI therapy, and the combination therapy has taken two different forms. One is a combination of checkpoint inhibitor and antiangiogenic therapy, such as in the combination of atezolizumab and bevacizumab. The other is a combination of dual checkpoint inhibitor therapy. Here we are talking about the results of nivolumab and ipilimumab. Previously, we've talked about the combination of durva and tremi for the treatment of patients with HCC.  

So in this study, nivo was given for the first 4 cycles, nivo and ipi were given together, nivo 1 mg per kg, and IPI 3 mgs per kg every 3 weeks for 4 cycles. And then the CTLA-4 inhibitor ipilimumab was stopped. And this was followed by monotherapy nivolumab every 4 weeks until disease progression or up to 2 years. And it was compared to dealers' choice, lenvatinib or sorafenib. The median overall survival of nivo-ipi was 23 months versus 20 months with lenvatinib-sorafenib. The 24-month overall survival was 49% with ipi-nivo versus 39%. And the overall response rate with nivo-ipi was 36% compared to 13%. So again, significantly improved clinical activity.  

And when we talk about immunotherapy combinations, the question that comes to mind is how well is this tolerated? There's a lot of work and iteration that took place in figuring out what the right combination strategy of ipi and nivo should be, because some of the earlier studies did demonstrate fairly high adverse events in this group of patients. So on this study, we saw that grade 3 or 4 treatment related adverse events were seen in 41% of people who received nivo-ipi and 42% if they received lenvatinib or sorafenib. So, certainly a high proportion of treatment related adverse events, but probably also reflective of the disease population, which is being tested, because those numbers were fairly similar in the control arm as well. 

So we've known that nivo-ipi is active in HCC. There is an approval in the second-line space, so it remains to be seen if this data helps propel nivo-ipi to the first-line space so we end up with another combination regimen for patients with advanced hepatocellular carcinoma. 

Geraldine Carroll: Excellent. Well, before we wrap up the podcast, I'd like to ask you about LBA3511. In this study, investigators looked at total neoadjuvant treatment with long course radiotherapy versus concurrent chemoradiotherapy in local advanced rectal cancer with high risk factors. So this was a multicenter, randomized, open label, phase 3 trial. What are your key takeaways here?

Dr. Shaalan Beg: Key takeaway here is that total neoadjuvant therapy was better than the conventional chemoradiation followed by chemo. So this clinical trial enrolled people with T4a/b resectable disease with clinical N2 stage, and they were randomized, as you mentioned, to receiving chemoradiation with radiation capecitabine followed by surgery, and then CAPOX or capecitabine versus chemo, short-course radiation, and additional chemotherapy followed by surgery. 

And when we compare both arms, the total neoadjuvant therapy led to improved disease-free survival, improved PCR rates compared to standard concurrent neoadjuvant chemo radiotherapy in this group of patients. The two arms were fairly well-balanced. The number of T4 lesions was a little higher in the chemoradiation group. There were 49% in the chemo radiation group versus 46% had clinically T4 disease, but the nodal status was fairly similar. We should keep in mind that the other baseline characteristics were fairly well balanced. 

And when we look at the outcomes, the disease-free survival probability at 36 months was 76% in the total neoadjuvant group compared to 67% with chemoradiation. And the metastasis free survival in total neoadjuvant therapy was 81% versus 73%. So a fairly compelling difference between the two arms, which did translate into an overall survival of 89% versus 88% in the two groups. So definitely higher disease-free survival and metastasis free survival, no difference on the overall survival with these groups. And it talks about the importance of intensifying chemotherapy upfront in this group of patients who can have a fairly high burden of disease and may struggle with receiving chemotherapy postoperatively.

Geraldine Carroll: Excellent. Well, thank you, Dr. Beg, for sharing your fantastic insights with us on these key studies from the 2024 ASCO Annual Meeting. It's certainly a very exciting time in GI oncology.

Dr. Shaalan Beg: Absolutely. Thank you for bringing these studies out, because I think a lot of these are practice-changing and can start impacting the clinical care that we're giving our patients right now.

Geraldine Carroll: Thank you to our listeners for joining us today. You'll find links to the abstracts discussed today in the transcript of this episode. Finally, if you value the insights that you hear on the podcast, please take a moment to rate, review, and subscribe wherever you get your podcasts.

 

Disclaimer:

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.

Guests on this podcast express their own opinions, experience, and conclusions. Statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

 

Find out more about today’s speakers:

Dr. Shaalan Beg  

@ShaalanBeg  

 

Follow ASCO on social media:  

@ASCO on Twitter 

ASCO on Facebook 

ASCO on LinkedIn 

 

Disclosures: 

Dr. Shaalan Beg:  

Consulting or Advisory Role: Ispen, Cancer Commons, Foundation Medicine, Genmab/Seagen  

Speakers’ Bureau: Sirtex  

Research Funding (An Immediate Family Member): ImmuneSensor Therapeutics  

Research Funding (Institution): Bristol-Myers Squibb, Tolero Pharmaceuticals, Delfi Diagnostics, Merck, Merck Serono, AstraZeneca/MedImmune