Doctors James Ferriss, Linda Duska, and Jayanthi Lea discuss the promise and the challenges of targeting the immune system with immune checkpoint inhibitors, or ICIs, in cervical and endometrial cancers. They also examine emerging data that support the use of ICIs in recurrent cervical cancer, the potential for curing some patients with advanced endometrial cancer, and molecular factors that make cervical cancer a good target for immunotherapy.

TRANSCRIPT

Dr. James Stuart Ferriss: Hello, and welcome to the ASCO Daily News Podcast. I'm Dr. James Stuart Ferriss, your guest host of the ASCO Daily News Podcast today. I'm an associate professor of gynecology and obstetrics and the Gynecologic Oncology Fellowship Program Director at Johns Hopkins Medicine. In today's episode, we'll be discussing the use of immunotherapy in cervical and endometrial cancers to advance the treatment of these malignancies. I'm delighted to be joined by two acclaimed experts in this space, Dr. Linda Duska and Dr. Jaya Lea.

Dr. Duska is a professor of obstetrics and gynecology and serves as the associate dean for clinical research at the University of Virginia School of Medicine. Dr. Lea is a professor of obstetrics and gynecology and chief of gynecologic oncology at the University of Texas Southwestern Medical Center.

Our full disclosures are available in the transcript of this episode, and disclosures related to all episodes of the podcast are available at asco.org/DNpod. Drs. Duska and Dr. Lea, it's great to have you on the podcast today.

Dr. Linda Duska: Thanks, Dr. Ferriss.

Dr. Jayanthi Lea: Thanks, Dr. Ferriss.

Dr. James Stuart Ferriss: So, let's get started. In recent years, we've had a revolution in the treatment of advanced endometrial and cervical cancers with improved outcomes for patients treated with immunotherapy. And when we say immunotherapy, we're specifically talking about immune checkpoint inhibitors today. A few of these agents have actually been approved in the United States for the management of these diseases. In our discussion, I'd like to review the promise and challenges of targeting the immune system in patients with advanced endometrial and cervical cancers, as well as review the most recent evidence we have in these spaces.

Let's start with cervix. We've had a lot of improvements in outcomes here, Dr. Lea, and with cervical cancer, we've seen improved overall survival with the incorporation of immunotherapy along with chemotherapy and anti-angiogenic therapy for advanced and recurrent disease. Can you remind us why cervical cancer is a good target for immunotherapy?

Dr. Jayanthi Lea: Yes, Dr. Ferriss. Immunotherapy for cervical cancer is supported by several molecular factors. And I think first and foremost, it's so important to remember that the majority of cervical cancers are HPV-positive. And HPV-positive cancers can induce a high level of inflammation, but this high level of inflammation actually contributes to evasion of immune surveillance. What it also does is that it's responsible for the induction of PD-L1. And we've seen several studies that have shown that cervical cancers express PD-L1 anywhere from 50 to 90 percent of cases. Other pertinent factors to consider are that cervical cancer can be considered a tumor with a high tumor mutational burden. So, the number of somatic mutations that we see in the DNA can be considered as a proxy for neoantigens. And so the higher the level of neoantigens, the more immunogenic the tumor. And then lastly, about 1 in 10 cervical cancers present with microsatellite instability, which is an already established key biomarker for the response team in care.

Dr. James Stuart Ferriss: So, thinking about targeting PD-L1, what clinical evidence do we have that supports the use of immune checkpoint inhibitors in recurrent cervical cancer?

Dr. Jayanthi Lea: We now have several studies that have shown a benefit for immune checkpoint inhibitors. For example, KEYNOTE-158 was a phase 2 basket [trial] that investigated the antitumor activity of pembrolizumab, which is a PD-1 inhibitor, in multiple cancer types. And specifically for patients with previously treated advanced cervical cancer, we were able to see an overall response rate of about 15% in those patients who had PD-L1 positive. And similarly, the EMPOWER CERVICAL-1 study, which was a phase 3 randomized trial that investigated the efficacy of cemiplimab, which is another PD-1 inhibitor, versus investigator's choice of single agent chemotherapy, showed a significant difference in median overall survival and progression-free survival in the cemiplimab group. There are several other studies that have investigated the efficacy of PD-1 or PD-L1 inhibitors in cervical cancer. One specific PD-1 inhibitor is nivolumab. In CHECKMATE-358, nivolumab was associated with an overall response rate of 26% in women who had recurrent/metastatic cervical cancer.

Dr. James Stuart Ferriss: Dr. Duska, do you have any thoughts?

Dr. Linda Duska: I'm really interested in PD-L1 as a biomarker because in the KEYNOTE-A18 study, which we're going to get to, 95% of patients were PD-L1 positive by CPS, which is the scoring system that we use in cervix cancer. And some of the studies that you already mentioned, including BEATcc, which we're also going to talk about, reported results where PD-L1 wasn't even considered. And so it begs the question, since PD-L1 is actually – again, depending on when in the course of disease you look at it, but more recent studies suggest 95% of cervical cancers express PD-L1, and – agnostic is the word I was looking for – it seems at least in BEATcc and similar trials that PD-L1 is agnostic, but I wonder if PD-L1 is really a good biomarker for response to checkpoint inhibitor therapy and I wonder what your thoughts are.

Dr. Jayanthi Lea: I think that's an excellent question. To your point, that's correct that we saw in KEYNOTE-A18 that more than 90% of the patients had PD-L1 positivity and the result is sort of generalizable to all comers. That's still a matter of debate as to how we see PD-L1 as a biomarker to incorporate checkpoint inhibitors in the treatment of patients.

Dr. James Stuart Ferriss: So, let's talk about the use of immune checkpoint inhibitors in the frontline setting. Until recently, we haven't seen much improvement in overall survival since the introduction of anti-angiogenic therapy to the chemotherapy backbone, and that was in GOG 240. Let's talk about the changes that have recently occurred in this space.

Dr. Jayanthi Lea: So, we've had some very exciting data specifically from initially KEYNOTE-826 and its primary metastatic or first line salvage settings. So, KEYNOTE-826, which was a phase 3 randomized, controlled trial was very practice-changing for us because it showed that incorporation of pembrolizumab to the first-line treatment of patients with metastatic or recurrent cervical cancer, really changed the landscape for treatment in this group of patients. So, keep in mind that prior to the study, the standard of care was carboplatin, or cisplatin with paclitaxel plus or minus bevacizumab, which yielded a median overall survival range in anywhere from 13 to 17 months depending on whether you use bevacizumab or not. And then adding pembrolizumab to that regimen, increase the median overall survival to 24 months, which is very promising.

Dr. James Stuart Ferriss: If I remember correctly, KEYNOTE-826 allowed investigators choice, use of bevacizumab, and initially we were unsure about which regimen was best. Has there been additional data since?

Dr. Jayanthi Lea: There has been additional data since. And another study that was done in the same vein was the BEATcc trial, which also looked at the different checkpoint inhibitors, atezolizumab in combination now with bevacizumab and platinum-based chemotherapy. And the control arm for this study was the GOG 240 regimen, which included bevacizumab. And this study showed both a progression-free and overall survival difference. The median overall survival in this study was 32 months with the incorporation of the checkpoint inhibitor to the bevacizumab and platinum-based chemotherapy. So, the way that I look at it is that the BEATcc trial basically confirmed the findings of KEYNOTE-826 and highlights that it is important for us to incorporate checkpoint inhibition with immunotherapy along with bevacizumab when we're treating patients with a recurrence.

Dr. James Stuart Ferriss: Also, folks with primary advanced treatment for cervical cancer, this would be a great regimen, is that right?

Dr. Jayanthi Lea: Absolutely. Primary advance, we would want to use the same regimen for that.

Dr. James Stuart Ferriss: Okay. What about locally advanced in primary treatment? What advances have we seen?

Dr. Jayanthi Lea: So we've had some major changes in that field as well, especially with the recent KEYNOTE-A18 data where pembrolizumab was administered in combination with external beam radiation and concurrent chemotherapy. And this study showed that there was significant and clinically meaningful improvement in progression-free survival compared to chemoradiation alone. Specifically, the progression-free survival at 24 months using pembrolizumab with chemoradiation was 68%, and 57% when in the placebo group. The hazard ratio for disease progression was 0.7 and no new safety signals were observed, which is fantastic, especially given the 0.7 hazard ratio that received PFS.

Dr. James Stuart Ferriss: Yeah, absolutely. These patients with locally advanced cervical cancer often are quite symptomatic, and the prospect of adding chemo, radiation, and now immunotherapy on top of that is really encouraging to see that it was such a well-tolerated regimen. I believe that there were patient-reported outcomes recently reported at SGO.

Dr. Jayanthi Lea: Absolutely. So, the safety profile of pembrolizumab and chemoradiation was consistent with the known profile of the individual treatment components. And no new safety signals emerged in the pembrolizumab chemoradiation arm. So, you're right. It was very well tolerated.

Dr. James Stuart Ferriss: What would you say are the takeaways for folks who are seeing these patients in the community? These locally advanced cervical cancer patients that are now adding immunotherapy in a space that we have not used routinely in the past in terms of combining it with chemo radiation in gynecologic cancer. What are some things they should be looking out for?

Dr. Jayanthi Lea: Well, I think that with the hazard ratio of 0.7 and the patient-reported outcomes showing no new signal, I think we can say that there is a positive benefit-to-risk profile of adding pembrolizumab in combination with chemoradiation, and that we should feel comfortable using this regimen. Now, of course, we have individualized patient care, and be able to know when to use bevacizumab, when to use immunotherapy. So, taking the whole patient into consideration becomes important. But for those individuals who are able to receive these drugs who don't have concrete issues to not receive these drugs [then I'd say we could] incorporate them since the safety profile is set.

Dr. Linda Duska: I would add to that, Dr. Ferriss, that right now we only have FDA approval in the U.S. for stage 3-4A disease, and that's 2014 staging. Mind you, we are now in 2018, so we should be very careful in and follow the correct FIGO staging. But the FDA only gave approval for stage 3-4A disease, even though the study included patients with earlier stage disease and positive nodes.

Dr. James Stuart Ferriss: That's a great point, thank you.

So, Dr. Duska, thinking about endometrial cancer and advanced endometrial cancer, we have seen a similar revolution in the care of patients over the past few years, with major shifts in our approach. Can you remind us how we got here?

Dr. Linda Duska: Yes, I would say in the '90s and before, and maybe even in the early 2000s, we used a lot of radiation for endometrial cancer as adjuvant therapy following surgery. The general consensus and what we were all taught was that this was a chemotherapy-resistant disease. And then we learned from a variety of GOG at the time, Gynecologic Oncology Group trials, that this disease is actually chemosensitive. And we went through a series of chemotherapy drugs, ranging from adriamycin cisplatin to taxel adriamycin cisplatin, and finally to taxel and carboplatin, demonstrating that this disease is actually quite chemosensitive.

With this realization came the idea that maybe it would be important to combine chemotherapy and radiation particularly in high-risk endometrial cancer cases, so those with positive nodes or patients with high-risk histology such as clear cell or serous cancers. So two very important trials were done, one of them was PORTEC-3 and the other was GOG-258, which looked at combining chemo and radiation together to see if we could do better than one or the other alone. And they were very different trials, and they looked at different populations of patients and they looked at different things. For example, PORTEC-3 randomized patients to receive chemotherapy and radiation versus radiation alone, while 258 looked at chemotherapy and radiation versus chemotherapy alone. Without going into a great amount of detail, I think what we learned from both of those studies, and I think surprised many of us, that the arms that included chemotherapy, those patients did better.

In fact, the results of GOG-258 can be interpreted – and this is somewhat controversial – but can be interpreted that many of these high-risk patients don't need radiation at all, or perhaps need tumor-directed radiation. For example, chemotherapy followed by tumor-directed radiation either to the vaginal cuff, because the vaginal cuff is at risk for recurrence, or perhaps to an area of concern, maybe the cervix if there were cervical involvement or if there is a particular concern for local recurrence in a particular patient. So, I think the pendulum has swung from almost always using radiation alone to, in more modern day, using chemotherapy and using radiation much more sparingly, and then comes immunotherapy.

Dr. James Stuart Ferriss: So, update us on the results of NRG-GY018 and RUBY?

Dr. Linda Duska: So, we've already talked about the KEYNOTE basket trials, which really contributed a lot to our understanding of the importance of MMR deficiency and microsatellite unstable disease. The KEYNOTE-158 study and the GARNET study showed us how important it was for women with MMRd and MSI endometrial cancer to receive checkpoint inhibition, and actually with remarkable response rates to women who had already been pretreated. But we also learned from the GARNET trial, which included MMRp patients, that the response rates in MMRp were not that great. And that led to KEYNOTE-775, which looked to combine pembrolizumab with a VEGF inhibitor, lenvantinib, to see if we could make the cold tumor hot. And indeed, we could. And not only could we improve the response rate in patients with MMRp tumors, but we could also improve the response rate in patients with MMRd tumors. They did better with the combination than they did with pembro alone.

That led to the idea of combining checkpoint inhibitors with chemo upfront. The idea there was we were going to take paclitaxel and carboplatin, which were our backbone for advanced or recurrent endometrial cancer, and add immunotherapy to that. And to your point, GY018 and RUBY trials did just that. And they allowed MMRd and MMRp patients and combined paclitaxel and carboplatin, either with dostarlimab in the case of RUBY, or pembrolizumab in the case of GY018. These studies, both of which were reported and published in the New England Journal of Medicine last year, showed remarkable findings in the upfront setting and potentially in the curable setting. And the OS data for RUBY were presented at SGO this year and were remarkable for MMRd patients. In the whole population, in the whole group in RUBY, there was a 16.4-month improvement in overall survival with the addition of dostarlimab which is just huge.

When you look at the MMRd group, I think Dr. Powell described the overall survival improvement as unprecedented. I believe that was the word that he used. Also, he called it very robust, with a hazard ratio of 0.32 for the group that got dostarlimab, and a median OS that was not reached. So really remarkable. In addition, in the MMRp group, there was a seven-month improvement in OS that was significant. So that's really amazing in the RUBY trial. It's also of note that the RUBY trial allowed carcinosarcomas, whereas the GY018 study did not. So, I think it's fair to say that these results apply to carcinosarcomas.

It's also really important to note that many of the patients in the immunotherapy group who received placebo, 41% of them got IO in a later treatment line, and these OS data still stand. So that's really interesting and hypothesis-generating. For GY018, we don't have mature OS data yet, so we can't talk about OS. But we saw a similar improvement in PFS in both arms, in the d and the pMMR, with an OS trend in both arms that was also reported at SGO. GY018 was a little bit different though, because they unblinded at the time of the PFS reporting last year, and so those patients were unblinded a lot earlier than the RUBY patients were. So, to interpret the data in that vein, the OS data is not mature, but we anticipate looking at the PFS curves and the preliminary OS curves, that the OS data will also be statistically significantly improved in core pembrolizumab in GY018.

What's also really interesting, and we haven't talked about molecular subtypes, is that when we look at the molecular subtypes in RUBY, and I'm sure we're going to see data on the molecular subtypes in GY018 coming up, different molecular subtypes of endometrial cancer respond differently to IO. And so, there's going to be lots of really interesting data coming our way soon that we're really excited to see, and that will help us triage patients appropriately into treatment regimens.

Dr. James Stuart Ferriss: Dr. Lea, did you have a thought?

Dr. Jayanthi Lea: Yeah, I just wanted to comment that looking at the dMMR survival curve in the file that was presented recently, one thing that really strikes me is the importance of adding the IO at the time of initial treatment. The separation of the curves persists. And, like you just mentioned, Dr. Duska, I mean, some of those patients who received placebo then later on went to get an IO treatment, but at the same time, we still see a vast separation of those curves. So, I think it's really important to note that immunotherapy should be used upfront, especially in dMMR.

Dr. Linda Duska: Yeah, I completely agree with that. And I think that might be– I mean, this is just a hypothesis, but I think that that might be why we saw a difference with the addition of immunotherapy in the MMRp group, because it's possible that the chemotherapy created an immune environment that made the checkpoint inhibitor work more successfully than it would have otherwise. So, a really good point. You definitely need to include dostarlimab or pembrolizumab with the chemotherapy and then as maintenance therapy after.

Dr. James Stuart Ferriss: So, you mentioned, we're increasingly thinking about endometrial cancer in smaller and smaller buckets of patients with very prescribed molecular profiles. We don't yet have enough information to specifically tailor treatment. How are you approaching that today in patients that you see in clinic?

Dr. Linda Duska: Well, the MMR, and I'm interested in what you both are doing also, it's easy with the MMRd and MSI high patients. Those patients all should receive a checkpoint inhibitor, no question. The patients that are p53 mut, I test them for HER2, because we do have data to suggest that atezolizumab or TDX-d might be useful in those individuals, HER2 positive. And then the remaining patients, also called the NSMPs. That's a difficult group. I'm interested to know how you all manage them. I think that's the group where more clinical research is really needed to determine what the best treatment regimen for them is. But I'm interested in both of your thoughts on that.

Dr. James Stuart Ferriss: Dr. Lea?

Dr. Jayanthi Lea: I would have to say that I do exactly like you do, Dr. Duska.

Dr. James Stuart Ferriss: And I would say our approach is very similar. And we have a robust discussion always about the use of immunotherapy with chemotherapy and in patients who are proficient MMR. But I think that most of us believe that the PFS data is certainly compelling. And now the OS data from RUBY, very compelling in both groups. And so, we are routinely recommending the use of immunotherapy along with chemotherapy in these advanced patients.

Dr. Linda Duska: I've heard the argument made that GY018 required measurable disease, and so does not necessarily apply to patients without measurable disease. I'm not sure that I agree with that. I think there were clinical trial reasons why that was a requirement rather than biologic reasons. In addition, as we already discussed, RUBY included carcinosarcomas and GY018 did not. I don't think there's a reason to only use dostarlimab for carcinosarcomas, but that said, I don't know that pembrolizumab has an indication for carcinosarcomas. The devil's in the details, don't get too lost in the weeds. I think the take-home message here is that it's really important to use IO, particularly for the MMRd patients with endometrial cancer, upfront. And based on the OS that we saw in both RUBY and preliminarily in GY018, we may be curing some people with this regimen, and I think we should focus on that. The overall survival for advanced endometrial cancer is not great, and if we can improve that and potentially cure some people, that's a huge advance for our patients.

Dr. James Stuart Ferriss: Do you envision a day that we might even ask the question, "Do we need to do surgery?"

Dr. Linda Duska: So, the rectal data would support that assertion. I'm not sure that endometrial cancer and rectal cancer are the same thing. And I think that taking out a postmenopausal woman's uterus is a lot less morbid than potentially radiating or taking out somebody's rectum. I think a different question would be, is there a day when we would stop doing no dissection? We could definitely debate that, but I don't see that happening. Do you see that happening anytime soon? A stopping of hysterectomy for endometrial cancer?

Dr. Jayanthi Lea: I don't see that happening anytime soon. And I think, as you said, taking out the uterus, tubes, and ovaries, it does provide us with some information about whether you're even dealing with a secondary primary. But also, it's from a quality-of-life standpoint. If a woman has a large uterus, that's uncomfortable. Postmenopausal bleeding, avoiding bleeding during the course of treatment, so many reasons why I wouldn't be in too much of a hurry to want to not do surgery for these patients.

Dr. James Stuart Ferriss: So, we'll put a plug in for our fellow gynecologic oncologists that we still have a role to play in the incorporation of treatment regimens for patients with advanced uterine cancer. So it's not just medicine, there's still a role for surgery.

Dr. Linda Duska: I think that's very fair, yeah.

Dr. James Stuart Ferriss: Okay. I think that's all the time we have for today.

I want to thank our listeners for their time, and you'll find the links to all the studies we've discussed today in the transcript of this episode. And finally, if you value the insights that you hear on the ASCO Daily News Podcast, please take a moment to rate, review, and subscribe wherever you get your podcasts. Thank you.

Dr. Linda Duska: Thank you.

Dr. Jayanthi Lea: Thank you.

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. 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. James Stuart Ferriss

Dr. Linda Duska

@LDuska

Dr. Jayanthi Lea

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Disclosures:

Dr. James Stuart Ferriss:

Honoraria: National Board of Medical Examiners

Dr. Linda Duska:

Consulting or Advisory Role: Regeneron, Inovio Pharmaceuticals, Merck, Ellipses Pharma

Researching Funding (Inst): GlaxoSmithKline, Millenium, Bristol-Myers Squibb, Aeterna Zentaris, Novartis, Abbvie, Tesaro, Cerulean Pharma, Aduro Biotech, Advaxis, Syndax, Pfizer, Merck, Genentech/Roche, Cerulean Pharma, Ludwig Institute for Cancer Research, Leap Therapeutics

Patents, Royalties, Other Intellectual Property: UpToDate, Editor, British Journal of Ob/Gyn

Dr. Jayanthi Lea:

Consulting or Advisory Role: Roche

Update in Cervical Cancer Screening