Drs. Shaalan Beg and Shiraj Sen discuss notable advances in GI cancers featured at the 2023 ASCO Annual Meeting, including the PROSPECT and PRODIGE-23 trials in rectal adenocarcinoma, the MORPHEUS study in uHCC, and the NORPACT-1 trial in pancreatic head cancer.

TRANSCRIPT

Dr. Shaalan Beg: Hello, and welcome to the ASCO Daily News Podcast. I'm Dr. Shaalan Beg, your guest host for the podcast today. I'm the vice president of oncology at Science 37, and I'm an adjunct associate professor at UT Southwestern Medical Center. My guest today is Dr. Shiraj Sen. He is a GI medical oncologist and the director for clinical research at NEXT Oncology in Dallas.

Today, we'll be discussing practice-changing studies and other key advances in GI cancers that were featured at the 2023 ASCO Annual Meeting.

You'll find our full disclosures in the transcript of this episode, and disclosures of all guests on the podcast are available on our transcripts at asco.org/DNpod.

Shiraj, it's great to have you on the podcast today.

Dr. Shiraj Sen: Thanks so much for having me today, Shaalan.

Dr. Shaalan Beg: We saw exciting new data and great progress in GI oncology at the ASCO Annual Meeting. I was hoping we could talk about LBA2. This was the PROSPECT study that was presented during the Plenary Session. It's a randomized, phase 3 trial of neoadjuvant chemoradiation versus neoadjuvant FOLFOX chemo, followed by the selective use of chemoradiation, followed by TME or total mesorectal excision for the treatment of locally advanced rectal cancer. This is the Alliance N1048 trial. What are your thoughts on this study?

Dr. Shiraj Sen: Thanks, Shaalan. It was great to see another GI study presented in a Plenary Session, and I thought this was a great trial that really took us back to thinking about why we do chemoradiation as well as chemotherapy perioperatively in locally advanced rectal cancer. And asking the important question of is there a select patient set or subset where we might be able to safely omit the chemoradiation piece.

To me, the impressive part was this study enrolled from 2012 to 2018. In 2012, when this treatment really started enrolling, the standard of care was long-course chemoradiation for five and a half weeks, followed by surgery, followed by adjuvant chemotherapy with FOLFOX or CAPOX. During this time, a lot of the practices of these patients have shifted from that to giving total neoadjuvant therapy, where we bunch the chemotherapy and chemotherapy upfront prior to the patient undergoing surgery. And this study really asked us to take a look at both practices and ask the question of which one is better and is it possible to de-escalate care for patients who get upfront chemotherapy and omit the chemoradiation and still have similar outcomes.

I thought it was very interesting that this was done in a non-inferiority-type manner, and we can talk more about that in a few minutes as well. But taking that all into context, the fact that in this study, that the non-inferiority endpoints were met for both disease-free survival as well as overall survival in the patients who were able to omit chemoradiation, I think in the big picture sense told us that there truly might be a patient subset where—this is in patients with T2 node-negative disease or T3 node-negative or T3 node-positive disease—where we might be able to safely exclude the chemoradiation and still have similarly effective outcomes for these patients.

Dr. Shaalan Beg: Those are great points, especially when we have started to think about colon cancer and rectal cancer as many different diseases based on their location. And we know that in some instances their biology can be different as well.

Can you talk a little bit about who those patients are that were enrolled on this trial? Because when I think about the German rectal study that led to us using neoadjuvant chemoradiation, the data was really around pelvic control of disease and sphincter preservation. So how did the patients who enrolled in this trial relate to the typical person with rectal cancer who walks through your doors?

Dr. Shiraj Sen: Yeah, great point. I think we should point out the inclusion-exclusion criteria for this study. These patients were only those who were, again, T2 node-positive or T3 node-positive or negative, patients for whom chemoradiation would be indicated in the setting, and patients for whom they'd be good candidates for sphincter-sparing surgeries. So, tumors that are quite up high. These are not for individuals who have tumors requiring an APR. These are not for patients who have clinical T4 tumors. And this is not applied, again, to those high-risk patients who have 4 or more pelvic lymph nodes that are 1 cm in size or larger in the short access. And so, patients who need essentially an APR and the high-risk T4 tumors who are, I think, better suited by something like we'll talk about later in the PRODIGE study.

I think one last point that might be worth making here on the PROSPECT trial is that it was a non-inferiority trial. And in my opinion, this was really a great use of a non-inferiority study. I believe that when there's a new treatment under consideration used in a non-inferiority study, it should be because that therapy or modality of treatment is safer, more cost-effective, or could help increase access to care without compromising efficacy, and ideally maybe more than one of the above. And in this case, I think really all of those checkboxes are met.

In urban settings where we work, we think about access to radiation being quite plentiful, but when we get to more rural areas, or parts of the world where they may not have access to radiation like we may, I think this data can help drive care for a number of patients there. It can certainly be more cost-effective as it allows the omission of radiation. And certainly, from some of the PRO data that they presented, it certainly can be felt to be safer and help omit some toxicities as well.

Dr. Shaalan Beg: Yeah, you mentioned a total neoadjuvant therapy and we seem to be entering this space in rectal cancer where the decision on which modalities an individual person will need for the management of their disease and what sequence they will need is all up for debate, whether that's chemotherapy or radiation, long-form, short-form radiation. And we also heard some results at earlier ASCO meetings around the omission of surgery in people who've had complete clinical responses as well.

And you mentioned total neoadjuvant therapy and at ASCO this year we heard the results from LBA3504, which is a PRODIGE-23 trial. The investigators reported 7-year results of this phase 3 study from the UNICANCER group in France. This study is really pushing the envelope. What are your key takeaways here?

Dr. Shiraj Sen: Great point. I think this study, especially when taken in conjunction with the PROSPECT trial, highlights the fact that these patients really can have heterogeneous diseases and ones that really require careful consideration and discussion at multidisciplinary tumor boards. Unlike the patient population in the PROSPECT trial, the PRODIGE study did treat patients with higher-risk disease. So these were patients with clinical T3, T4 tumors and so higher risk, and asked the question now with more mature 7-year follow-up of, when compared to receiving the standard of care at the time, which was a chemoradiation followed by TME, followed by adjuvant FOLFOX for 12 cycles or the capecitabine, does TNT giving again now modified full FOLFIRINOX for six cycles followed by chemoradiation followed by TME and then adjuvant FOLFOX, do the improvements in both disease-free survival, overall survival, and metastatic relapse rate, do they hold up, and/or are there any differences in local control?

And again, here they demonstrate that even with longer-term follow-up, that the improvements in OFS, DFS, and metastatic relapse rate, really do hold up even with longer-term follow-up. And so, for these patients with higher risk disease, it does seem that giving induction chemotherapy with modified FOLFIRINOX before chemoradiotherapy really might be kind of best practices. The safety profile, even with longer-term follow-up was unchanged. There was not any increase in local recurrences. And again, looking at quality of life metrics there seemed to be similar or maybe improved quality of life for patients who receive the TNT approach. And now again, I think the next step is, as the presenter mentioned, investigating this even in a more tailored fashion, as was done with the PROSPECT study.

Dr. Shaalan Beg: Let's change gears and talk about liver cancer. Abstract 4010 showed the results of the MORPHEUS-liver study. This was a phase 1b/2 randomized trial of tiragolumab in combination with atezolizumab and bevacizumab for people with unresectable locally advanced or metastatic hepatocellular cancer. It's really exciting to see innovations with immune therapy changing how we've managed hepatocellular cancer in the last few years. And here, we're seeing an addition of a third agent to an already approved regimen of atezolizumab and bevacizumab. I was really curious to hear what your take-home message is from this study.

Dr. Shiraj Sen: Yeah, this was another very interesting abstract that was presented at ASCO this year. It's hard to believe that it was only 3 years ago that we first got the approval of atezo plus bev, and that it took more than a decade to really have us as a field improve on outcomes for patients with liver cancer above and beyond giving sorafenib. And here we are just 3 years later, already launching new phase 3 studies from these sorts of early-phase adaptive signal-seeking studies. The investigators as a whole should be commended for the speed at which new drug development has really progressed in liver cancers after, again, quite a lull we had in the pre-I/O days.

It's encouraging to see that in just 3 years that there's another phase 3 study now being launched in HCC on the heels of this data combining the atezo-bev backbone to the anti-TIGIT molecule tiragolumab. Now, I know there was a lot of discussion and some criticism of this study and what the real effects of adding tiragolumab to atezo-bev might be because of the underperformance of the control arm. In this study, the atezo-bev control arm, it should be noted that was only 18 patients, had a response rate of only 11%. And of course, with longer-term follow-up of the IMbrave150 study, we know that with the atezo-bev, we expect a response rate of about 30%. And so how a real-world population of individuals receiving atezo-bev would compare to those receiving tiro-atezo-bev has been discussed. But I think the only real way to answer that question would be with a large, randomized phase III study. And it's encouraging to see that one is being launched to ask that question.

Dr. Shaalan Beg: Absolutely. Let's change gears and talk about pancreatic cancer. LBA4005 explored short-course neoadjuvant FOLFIRINOX versus upfront surgery for people with resectable pancreatic head adenocarcinoma in the NORPACT-1 study. This is a multicenter randomized phase 2 trial and we're starting to see the reporting of clinical trials evaluating the sequencing of systemic therapies for resectable disease. We've heard studies for neoadjuvant therapy for borderline resectable as well as resectable trials in previous meetings. But there's a lot of discussion around the NORPACT-1 trial which may be causing some people to pause on our current understanding of treatment sequencing for resectable disease. I'm curious to hear what your take homes are.

Dr. Shiraj Sen: Thanks. Yes, I thought this was a very interesting study as well. Depending on which institution one practices in, in recent years, many have shifted their practice for individuals with resectable pancreatic cancer from administering full FOLFIRINOX or adjuvant therapy only after surgery to giving it in the neoadjuvant setting based on, again, a number of smaller studies, some that are single institution. This is one of the first studies that in a randomized fashion has asked the question in just resectable pancreatic cancer. So we're not talking about borderline resectable or other patients.

But in resectable pancreatic cancer, whether there are differences now comes if patients receive surgery first, followed by FOLFIRINOX-only adjuvant setting or essentially getting perioperative FOLFIRINOX and so neoadjuvant, followed by surgery, followed by, as tolerated, four cycles of adjuvant FOLFIRINOX. And I was a little surprised by some of the results and to me some of these data were a little intriguing.

Specifically, I think if we take a deeper look like the discussant had after the presentation, there are, I think, some unanswered questions. Specifically, half the patients were randomized to receive neoadjuvant FOLFIRINOX and half of them received upfront surgery. But in the group of individuals who received neoadjuvant FOLFIRINOX, it looked like only half of them completed neoadjuvant chemotherapy. And some answers into kind of why that was, and what it was about those patients then who were in the neoadjuvant arm, is one thing that comes to mind.

Secondly, what I thought was interesting was this study was that it was designed very well to try to take out as much heterogeneity as possible. However, in both arms, there was actually quite a substantial number of individuals who ended up receiving gemcitabine-based chemotherapy. And that's even in the patients who received neoadjuvant FOLFIRINOX, and individuals who received neoadjuvant FOLFIRINOX, only 25% post-op went on to receive adjuvant FOLFIRINOX. And 75% almost received gemcitabine-based therapy. And again, why so many patients received off-protocol adjuvant therapy is something that kind of struck me.

I think the third and final thing that really struck me was, in the patients that received neoadjuvant FOLFIRINOX, there was a higher rate of R0 resections. 56% of patients had an R0 resection compared to those who got upfront surgery, where there was only a 39% rate and similarly kind of higher levels of N0 resection. And yet, despite all of this, again, the authors did show quite clearly that there were not any significant improvements in outcomes for patients that received neoadjuvant therapy, but kind of how improved surgical endpoints do not translate to overall survival and overall endpoints; I think there are still some questions there.

However, I do agree overall that despite these limitations with the conclusions of the author, that at this time at least, it's not clear; the results don't support the widespread use of neoadjuvant FOLFIRINOX as a standard of care for resectable pancreatic cancer. Fortunately, there are studies ongoing, like the Alliance [for Clinical Trials in Oncology] study and the PREOPANC-3 study that hopefully will kind of help settle this verdict.

Dr. Shaalan Beg: Yeah, it's a stark reminder that we need better treatments. I think we've been shifting the sequencing of these treatments and slicing them in as many ways as we can. And the core challenge is in finding better systemic therapies that have been found to be effective in advanced stage as well as in curative stages like this. And one of the points that bothered me about this trial was the drop-off that they saw at the beginning when the biliary system was being drained, or they were getting biopsies because folks who went for surgery upfront didn't always require those procedures. They didn't require histologic diagnosis either. But as is standard practice, before we give systemic therapy, we require psychologic confirmation. And that may have introduced a delay of a couple of days or a couple of weeks, which could have resulted in some imbalances in how survival is measured and how folks were doing. Because, as you know, a lot of times people diagnosed with this disease can be fairly sick, and a matter of a couple of days or weeks can make a big difference in terms of treatment with those.

I'm really excited to wait and hear how the Alliance study and the PREOPANC follow-up trials pan out and as a very important cautionary note for everyone, both the folks who have adopted neoadjuvant therapy and those that have not followed the data. And kudos to the investigators for completing that trial.

Dr. Shiraj Sen: Yeah, I fully agree. I'm glad to see that these trials are being run. I think we should not take anything away from the fact that these are very challenging trials to run. I think we certainly owe a big kudos to the patients who enroll in these studies who have resectable disease, but they're still willing to go through the process of an extra consent form, an extra kind of screening process, additional testing required to go into a clinical trial. And it's only because of them that we're able to run these studies and, as a field, get some answers on how to best take care of our patients.

Dr. Shaalan Beg: Shiraj, thank you so much for coming to the podcast today and sharing your valuable insights on the ASCO Daily News Podcast.

Dr. Shiraj Sen: Thank you so much for having me, and to all of the ASCO staff for having this podcast.

Dr. Shaalan Beg: And thank you to our listeners for your time 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 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. Guest 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.