The Pros and Cons of Triplet Chemotherapy for Pancreatic Cancer

Dr. Shaalan Beg and Dr. Mohamed Salem discuss novel therapies in gastrointestinal cancers, including CAR T therapy and the CodeBreak-101 trial in mCRC, new advances in uHCC in the HIMALAYA trial, and an exciting update from the NAPOLI-3 trial in pancreatic cancer, ahead of the 2023 ASCO Annual Meeting.

TRANSCRIPT

Dr. Shaalan Beg: Hello, and welcome to the ASCO Daily News Podcast. I'm Dr. Shaalan Beg, your guest host of the podcast today. I'm the vice president of oncology at Science 37 and an adjunct associate professor at UT Southwestern Simmons Comprehensive Cancer Center. My guest today is Dr. Mohamed Salem, a GI oncologist at the Levine Cancer Institute at Atrium Health. We'll be discussing key posters and oral abstracts in GI oncology that will be featured at the 2023 ASCO Annual Meeting.

Our full disclosures are available in the transcript of this episode, and disclosures of all guests on the podcast can be found in our transcripts at asco.org/DNpod.

Mohamed, thanks for coming on the podcast today.

Dr. Mohamed Salem: Thanks, Shaalan.

Dr. Shaalan Beg: There's some interesting studies in colorectal cancer that I'd like to get us started with today. Abstract 3547 is titled "A Phase I Dose-escalation Study of GCC19 CAR T: A Novel Coupled CAR Therapy for Patients with Metastatic Colorectal Cancer." What are your thoughts on the study?

Dr. Mohamed Salem: Actually, this was a very exciting study to see coming out in GI cancer, especially colorectal cancer. As you know, CAR T made its way to the treatment of lymphoma and other heme malignancies. In fact, we saw a fascinating response and outcome using that technique and that niche in the immunotherapy module. The challenge we had was that we could not replicate this in solid tumors until very recently. I'm sure you had the same thing in your clinic, too. A lot of patients with GI cancer or colorectal cancer come to you and say, "Okay, why can't I have CAR T?" And the response was, "We don't know if it's effective or if it's going to work yet." Here at our center, we had a phase 1 study, I think that was looking also at CAR T and solid tumors, particularly prostate cancer. So that I think was very exciting to see that technology is making its way to the solid tumor. I was very pleased to see this CAR T study coming out from the work of our Chinese colleagues looking into this in the CRC space.

Obviously, as you know, in colorectal cancer, we made a significant advancement, but I don't think we made enough advancement yet, and especially for refractory patients, patients with refractory disease who have underwent multiple lines of therapy. And this study actually addressed the need for those patients. So in this study, that was a phase I escalation dose, very much is we looked at about 13 patients who had metastatic CRC, they had at least two lines of therapy. So in what we say is a "refractory setting," unfortunately for those patients, we don't have large treatment options. And they used two doses, the first dose and the second dose that was a little bit higher. And the interesting part is that they were able to see very nice responses on this patient population. In the lower dose, I think the response was the PFS was about 1.9 months. But when they went up on the dose, actually the PFS was 6.3 months, which I think in the refractory setting is very meaningful.

And also the median overall survival for the first group was 13 months, which in the refractory setting is something we don't see often, and the higher dose was 18 months, which was even better. So there was a trend that higher doses are perhaps more effective or have better efficacies than lower doses, but also in terms of side effects, actually patients were relatively able to tolerate it well, and there were no surprising adverse events. So again, yes, that's 13 patients in total. So it's a very small study, but like everything else, the proof of concept sometimes is the first step and it's very important to see that data to suggest that this technology now can be utilized in solid tumors and CRC, especially now there is an unmet need for those patient populations. I'm sure you and I will see a lot of patients at the clinic with good progress status, and just looking for the next option, and I'm glad to see that. Hopefully, we can continue to build on that work.

Dr. Shaalan Beg: Another key abstract in colorectal cancer is Abstract 3513, the CodeBreak 101 study. This is a phase 1b safety efficacy trial of sotorasib plus panitumumab and chemotherapy with FOLFIRI for previously treated KRAS-G12C mutated colorectal cancer. And this is a really important study because even though KRAS-G12C represents a minority of KRAS mutated colorectal cancer, we know that this treatment can cause meaningful improvement in disease for other cancers like non-small cell lung cancer. And when sotorasib was tested as monotherapy in colorectal cancer, it saw an objective response rate of 9.7% that increased to 30% when added to panitumumab.

So in this trial, they took sotorasib plus panitumumab and added it to chemotherapy to see how it's tolerated and what its effectiveness is going to look like. And they enrolled people who had more than one or more lines of prior therapy for metastatic disease. They treated 33 patients. The most common side effect was dermatologic, which is probably related to EGFR-based therapy, and they saw a confirmed overall response rate of 58%. Side effects are those that we look to expect with this specific regimen. I don't see any additional safety concerns here, but this can be a big step forward for KRAS-G12C-altered colorectal cancer. What do you think?

Dr. Mohamed Salem: I totally agree. And again, it was very exciting to see that abstract and that result. I totally believe now, and I'm sure you would agree with me too, Shaalan, that we're moving from an era of one size fits all to a precision oncology and tailored treatment. And the fact now we have a treatment option for patients with a KRAS mutation is very exciting because before, we didn't have much that we can do about that mutation. So now it's not just a proof of concept. Now you're hitting that target with the chemotherapy and you're getting a 50% response rate. That's something interesting also to see for this patient population and as you highlighted as safety also, and the adverse event was not high and patients were able to tolerate it, which makes it more doable for us to use it.

Dr. Shaalan Beg: Yeah. And one of the challenges in the precision oncology space, which I'm sure you're experiencing in clinic as well, are the real-world applications of precision oncology and the drop-offs that happen that are preventing us from universal precision oncology - meaning the drop-offs that we see on eligible patients receiving the appropriate genomic testing, those who have genomic testing receiving the appropriate treatment. And we've seen a couple of fairly high-profile studies that are describing this in non-small cell lung cancer where the rates are not as encouraging as we would want it to be, which to me, as a physician, makes me worried that there are people out there who we don't know are carrying these mutations or have these mutations, and it hasn't been acted upon.

And related to that, there is an abstract at ASCO23, which is Abstract 3602, that looked at the real-world rates of FDA-approved targeted therapy and immunotherapy for people with metastatic colorectal cancer. They used the VA's National Precision Oncology Program data to study the prevalence of these mutations and how many of the folks ended up receiving the treatment that would be appropriate for those mutations. And this is a very exciting study. They looked at 908 metastatic colorectal cancer patients who underwent genomic profiling, 81% were colon and the rest were rectal. They found that 34% of patients harbored NRAS, KRAS, BRAF mutations, 9.6% were TMB-high, 7.7% had BRAF V600E, and 5.6% were MSI-high, which kind of puts the overall actionable variant prevalence in colon cancer at 47% and for rectal cancer at 44%.

And then they went down to see amongst those 424 eligible patients, how many ended up on appropriate therapy. And these were their numbers: for MSI-high 70%, TMB-high 47%, NRAS, KRAS, BRAF, wild-type 38%, BRAF V600E 17%. So nearly 30% of patients with MSI-high colorectal cancer did not receive immune checkpoint inhibitor therapy, and again, other aspects in terms of EGFR use, and I know that there are other challenges that may affect the use of EGFR inhibitors in colorectal cancer, but it really begs the point on aspects related to implementation science, on getting the testing and acting on those results. And I'm curious to what you're seeing that's being done on these initiatives nationally.

Dr. Mohamed Salem: I totally agree with you, Shaalan. This is a big problem we're facing day in and day out because we struggle to find treatment options for our patients. And I think if we're missing patient with targetable or actionable mutations and we're not utilizing that, I don't think that's a good situation to be in. And I think that's just a group effort. You have to work with the pathologist, you have to work with your team at the clinic. And as an oncologist treating this patient, we have to pay close attention to those markers. And frankly, just look for them. At least the ones that you know are going to have therapeutic implications.

I do also think patient advocacy has a huge role here and huge opportunities that they can contribute. I am sure you are familiar with the pancreatic study that was published by our colleague Mike Pishvaian in Lancet a year or two ago. I think he named it the Know Your Tumor Type. I think that should be the way forward now, not just for pancreatic but for any cancer. Patients should ask their oncologists what my tumor is. Is it MSI-high, is it KRAS-G12C, is it BRAF? Because it will affect the treatment. I think it's multi-layer and all of us should work in a cohesive manner to be able to not ever miss those markers which carry therapeutic potential.

Dr. Shaalan Beg: So moving on to hepatocellular carcinoma, Dr. George Lau and colleagues, they'll be sharing data from the phase 3 HIMALAYA study with hepatocellular carcinoma in the Annual Meeting that's Abstract 4004. And he looked at outcomes by occurrence of immune-related events for people who received tremelimumab and durvalumab. What are your thoughts on this study?

Dr. Mohamed Salem: This was a very interesting abstract to see. For a long time, we didn't have many treatment options in hepatocellular carcinoma. So, over the last two or three years now, I think we've made nice advancements in the therapeutic landscape. So, we have multiple options including immunotherapy which is very exciting for all of us to be able to utilize those powerful drugs in that disease. The question that comes out is who actually responds? Obviously, in HCC you don't have a lot of biomarkers like the immune therapy biomarkers like MSI-high and PDL-1, and TMB. It isn't really playing a huge role in HCC. So, as you know, the HIMALAYA study is a phase 3 study and examined the STRIDE regimen which is treme plus durva in the first line of patients with metastatic or unresectable HCC against sorafenib. And the outcome was in favor of the STRIDE regimen with improvement in OS response rate and duration of response and because of that, it became one of the standards of care for that disease. But Abstract 4004 is actually asking a very interesting question - whether immune-related adverse events can predict outcomes. Meaning like those patients who experience immune-related adverse events will likely do better compared to those patients who didn't experience immune-related adverse events or not. The idea of adverse events as a biomarker if you will, for efficacy is not new. I mean we saw that back in the renal carcinoma TKI, hypertension. People who had hypertension were more likely to have a better response. In the GI also there was some data suggesting that rash might be a biomarker in predicting response to EGFR. So the same question we're applying here - immune-related adverse events can function as a biomarker for efficacy for the immune system.

And there are some data out there in other tumors that may be the case, but I think at least to my knowledge in the HCC or GI, this was the first study to address that question. So just to remind our audience that the HIMALAYA was a phase 3 study using the STRIDE regimen as a frontline for patients with hepatocellular carcinoma, either unresectable or metastatic disease. And they compared the STRIDE which is durva-treme compared to the standard of care at that time was sorafenib. The primary endpoint was overall survival and they had secondary endpoint duration of response, response rate, and obviously adverse event.

The study was positive, it met its primary endpoint and OS was in favor of the STRIDE regimen compared to sorafenib. But that part of the abstract now is focusing mainly on those patients who had immune therapy and whether that was a STRIDE regimen or the third arm that durva alone treatment. And they're looking at those patients who had immune-related adverse events, and those who didn't have immune-related adverse events. So basically four groups of patients, the patient who had a STRIDE regimen, about 139 patients had immune-related adverse events, and about 249 didn't have immune-related adverse events. For the cohort who had durva alone, about 64 patients had immune-related adverse events, almost 300 patients had no immune-related adverse events.

And it was very interesting that at least in the STRIDE arm, those patients who experienced immune-related adverse events, their outcome was better than those patients who did not have immune-related adverse events. It's the same trend seen on the durva alone arm, but I think the number was very small to make a statistical value out of it. But I think at least in the STRIDE arm there was a suggestive trend toward the outcome of those patients who experienced immune-related adverse events. So I think this is in a way very interesting because we're always wondering if we give the same dose at least in immunotherapy like for everyone.

What I was wondering is if it's too much, too little, or just right. It's hard to know for sure. But perhaps in my opinion and just me trying to understand why, in my theory, maybe that's just an indication of patients receiving enough drugs and effective drugs that will translate into efficacy. But at the same time, I also wanted to just put a word of caution here because we don't want to see side effects as a good thing. I think we want to make sure that us as oncologists treating these patients and patients also don't see like it's good to have a side effect. Side effects associated with especially those grade 3 or 4 can be associated with significant problems and decreased quality of life. So, definitely should be looking at those side effects and be careful interpreting those data. But I think that is very interesting and I will look for more work on that.

Dr. Shaalan Beg: Let's move on to pancreatic cancer. We heard the results of the NAPOLI-3 clinical trial at GI ASCO and this year in ASCO 2023 we will hear the results of Abstract 4006 by Dr. O'Reilly that are presenting results of the 12 and 18-month survival rates from the study that compared NALIRIFOX or nano-liposomal irinotecan, 5-fluoro/leucovorin, and oxaliplatin versus nab-paclitaxel/gemcitabine for newly diagnosed pancreatic cancer patients. I'm interested to hear what you think about that study.

Dr. Mohamed Salem: Thank you, Shaalan. So this also is a very exciting abstract to see, and anyone who treats pancreatic cancer patients realizes that, unfortunately, even in 2023, we don't have a lot of treatment options. And yes, I think over the last decade we're now talking about second-line and third-line, but yet we still don't have a lot of treatment options. So, having more options is always good. But the question now is how do you sequence those chemotherapy options? Most of us obviously use FOLFIRINOX in the first line or gemcitabine and paclitaxel in the first line. Until very recently– because we didn't have a head-to-head comparison– we couldn't tell patients for sure if one is better than the other. I think we had some assumptions, but it wasn't really proven. It was just a cross-trial comparison.

So, the fact is that now we have that phase 3 trial looking at liposomal irinotecan, 5-fluoro/leucovorin and the oxaliplatin comparing to nab-paclitaxel/gemcitabine. To me, that was actually very exciting because now, at least, I can see a triplet chemotherapy drug compared to a doublet chemotherapy drug. And as you mentioned, Shaalan, the first initial read was positive in favor of the triplet regimen compared to the doublet, which I think was an important message to give to our colleagues and all of us that if you can, obviously, the triplet comes with side effects, but if you can deliver the triplet, that's perhaps a better starting point for the treatment.

But the study here, we're trying to get more read after more mature or more time-lapsing. So the initial study was initial read was positive. And I think this is good to see, too because it translates that even with a longer follow-up, we're still seeing the same benefit. So the OS rate in 12 months for the triplet was about 45% compared to 39.5% for the doublet, and the 18 months, a year and a half, was 26% compared to 19%. So, definitely, you can see an improvement in every single endpoint. OS in general was 11.1 months compared to 9.2 months, and PFS was also in favor of the triplet. So I think it's a message here to reinforce what we saw a few months ago in the initial presentation that, in fact, the triplet is associated with better outcomes if you can safely manage the toxicity and guide the patient through the process.

Dr. Shaalan Beg: Well, thank you very much, Mohamed. This was a lot of fun. Thanks for sharing your valuable insights with us on the ASCO Daily News Podcast.

Dr. Mohamed Salem: Thank you for having me and looking forward to the full presentation at the meeting. And please, if you haven't registered for the meeting yet, make sure you attend. It's a wonderful opportunity to learn from an expert in the field and also meet your colleagues and make new friends. I also want to take this opportunity to thank the ASCO Daily News Podcast team for taking the time, and also for our colleagues who reviewed these abstracts. This takes a lot of time and effort, and I think they're doing a wonderful job. So, thank you to all of them, and I'll see you all at ASCO.

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. I'll be back to cover late-breaking abstracts and other key advances in GI oncology after the annual meeting, so please join us for more key insights from ASCO 23 on the ASCO Daily News Podcast.

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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, experiences, 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.

Find out more about today's speakers:

Dr. Shaalan Beg

@ShaalanBeg

Dr. Mohamed Salem

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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

Dr. Mohamed Salem:

Consulting or Advisory Role: Taiho Pharmaceutical, Exelixis, Bristol-Myers Squibb, Exelixis, QED Therapeutics, Novartis, Pfizer, Daiichi Sankyo/Astra Zeneca

Speakers' Bureau: Genentech/Roche, Taiho Pharmaceutical, Daiichi Sankyo/Astra Zeneca, BMS, Merck