Durvalumab Plus Carboplatin/Paclitaxel Followed by Maintenance Durvalumab With or Without Olaparib as First-Line Treatment for Advanced Endometrial Cancer: The Phase III DUO-E Trial

In this "Podcast Takeover," Dr. Lidia Schapira guest hosts to discuss with Dr. Shannon Westin her own JCO paper, which reports on the DUO-E Trial. Dr. Ramez Eskander also joins in this lively discussion.

TRANSCRIPT

The guest on this podcast episode has no disclosures to declare.

Dr. Shannon Westin: Hello, everyone, and welcome to another episode of JCO After Hours, the podcast where we get in depth on manuscripts published in the Journal of Clinical Oncology. I am your host, Shannon Westin, Social Media Editor of the JCO and Gynecologic Oncologist by trade. And actually, I'm super excited today because we are going to have a podcast takeover because we are discussing my own work, which was simultaneously presented at the European Society of Medical Oncology 2023 Congress and published in the Journal of Clinical Oncology on October 21st, 2023. And this was the DUO-E trial, “Durvalumab Plus Carboplatin/Paclitaxel Followed by Maintenance Durvalumab With or Without Olaparib as First-Line Treatment for Advanced Endometrial Cancer.” Because we’re discussing this work and we wanted you to have an unbiased podcast discussion, Dr. Lidia Schapira, who is a Professor of Medical Oncology at Stanford University and an Associate Editor of JCO and the Art of Oncology podcast host, is going to take over this podcast and really just pepper me with questions about this exciting work. 

Welcome, Dr. Schapira. 

Dr. Lidia Schapira: Thank you so much. It's such a pleasure to be with you.

Dr. Shannon Westin: And before I turn over the reins, I also want to introduce one of my colleagues, who’s going to be providing quite a bit of insight on this topic, Dr. Ramez Eskander, who is Professor of Obstetrics, Gynecology, and Reproductive Sciences at the University of California, San Diego. And you will know he’s the principal investigator of the GY-018 study, which established pembrolizumab and chemotherapy as the new standard of care in endometrial cancer. Welcome, Ramez. 

Dr. Ramez Eskander: Thank you. Thank you, Dr. Westin. It's a pleasure to be here. And congratulations again to you and your study team for this exceptional work. 

Dr. Shannon Westin: Thank you. And congratulations to you. 

Dr. Schapira, thank you for being here and please do take it away.

Dr. Lidia Schapira: So let's start by having you tell us a little bit about the standard of care for women with endometrial cancer and advanced endometrial cancer prior to this study. Ramez, I'm going to direct this question to you first.

Dr. Ramez Eskander: For many years, actually since about 2012, carboplatin and paclitaxel, which ironically is a chemotherapy backbone really across all of our gynecologic tumors, emerged as the preferred doublet chemotherapy regimen for the management of advanced-stage metastatic or recurrent endometrial cancer. It evolved through a series of different clinical trials, in fact taking us from whole abdominal radiation, systemic chemotherapy, comparing single agents to doublets and then triplet regimen of TAP to carboplatin and paclitaxel, which ultimately, then, following the presentation of GOG Protocol 209 and its publication, as the chemotherapy backbone, being carboplatin and paclitaxel. And it’s been that way for many, many years.

Dr. Lidia Schapira: And how effective is the regimen?

Dr. Ramez Eskander: The response rates to carboplatin and paclitaxel are actually quite reasonable in the patients who have advanced-stage disease, particularly if they haven't had prior systemic chemotherapy. Response rates in the 50% to 60% range. The issue is that the responses tend to be limited and disease recurrence is an expectation in these patients who have advanced-stage disease. And so that really highlighted the importance of trying to continue to advance therapeutic opportunities in these patients to improve long-term outcomes. 

Dr. Lidia Schapira: As we think about improved long-term outcomes, we're thinking about a better treatment and also a kinder treatment, perhaps one that is also less toxic. Can you talk a little bit about the population of women with endometrial cancer? Are these older women? Do they have comorbidities? 

Dr. Ramez Eskander: What we’re seeing is, interestingly, there has been an evolution a bit in this space. Historically, we used to think about endometrial cancer as—the phrases we used to use are type I and type II. These type I tumors, we would say, are estrogen-driven malignancies; they tend to be seen in overweight or obese patients. And we would identify them in a theoretically younger patient population. And then we had these type II, or what we termed estrogen-independent malignancies, that we would see in an older patient population. Of course, with obesity came metabolic syndrome and other cardiovascular comorbidities, etc. But really, that narrative has evolved dramatically, and that’s really something that will be highlighted in, I think, our discussion of these studies today, where the nomenclature that we used to historically use has evolved because of our understanding of the molecular characterization of this disease. So we’ve really gone away from that, and now we understand that we’re seeing all of these different heterogeneous endometrial cancer types amongst patients of different ages, different comorbidities, different races and ethnicities. And so it’s created a more complex picture for us. But certainly, there are comorbidities that these patients face, and that’s important as we look to identify treatments strategies that are both effective and tolerable.

Dr. Lidia Schapira: My final question before we jump into this very exciting study is about the Cancer Genome Atlas work. Can you tell us how that’s changed the thinking and the design of the studies?

Dr. Ramez Eskander: It was a seminal publication, really, back in 2012/2013 looking at an assessment of endometrial cancers to try and determine whether or not all of these "endometrial cancers" that we used to enroll on a single study are similar or divergent. And it’s important because the study I referenced that really established the standard of care, GOG Protocol 209, as carboplatin and paclitaxel, there was no real consideration of molecular characterization at all. We enrolled all patients onto this study without thinking about these variables, of course, because it was designed, conducted, and completed before the TCGA data emerged. But what we learned from the TCGA is there appeared to be four distinct molecular subgroups. There were the POLE-mutated patient population. There was the mismatch repair deficient or MSI-high endometrial cancer population. There was the copy number-high or what we say are the p53-mutated. And then the last cohort was called the NSMP (no specific molecular profile). But now, that’s even evolved; some people term it TP53 wild type. That’s a bit of even a heterogeneous cohort amongst itself. So we’re going to take these subsets, independent of POLE and an MSI-high, and we’re going to look at TP53 or copy number-high, and that will probably be divvied out further, and the NSMP, and that will probably be subdivided. But really, it gave us these four components, which has then evolved. Many of you may have heard of the ProMisE algorithm or ProMisE Plus, which looked to take the data from TCGA so that we can start to really look at it in clinical practice. So it’s really revolutionized how we think about these patients, how we think about the disease, and how we design trials.   

Dr. Shannon Westin: And I just want to add to that because I think that it's so important, what Ramez said about the way we were developing trials, the way we were designing trials. We knew that these classifiers—we were learning these classifiers are prognostic. Now what we’re really trying to hone in on is how predictive they are. And certainly, one of the major classifiers that we’re going to talking about today is mismatch repair status, and that is most definitely predictive of response to therapies. But we’re still learning about the other classifiers and how we might adjust the way we treat people, even deescalating care for certain patients. That is still being proven in clinical trials, although we suspect that it’s going to be borne out as other clinical trials report.

Dr. Lidia Schapira: It's a perfect segue to this current trial. Tell us a little bit about the objectives and the design of DUO-E.

Dr. Shannon Westin: As Ramez said, the standard of care was chemotherapy. And so we wanted to see if there was a way to improve outcomes for these women with advanced and recurrent endometrial cancer in a really clinically relevant, meaningful fashion for patients. And so we knew that this TCGA classifier, the mismatch repair, was so important, and we thought that the addition of immunotherapy to chemotherapy would most certainly work in that population but could even work in the entire population because, generally, endometrial cancer seems to be a little bit more responsive to immunotherapy and to activation of the immune system than, say, some of our other gynecologic malignancies. And so we set out to see what the addition of durvalumab, which is a PDL-1 inhibitor, would add to chemotherapy. And this was two chemo as well as followed by durvalumab maintenance. 

But even further, we had some really kind of exciting science data from our lab that said that if we combined a PARP inhibitor with immunotherapy that we could accentuate on the response to therapy and we could get more benefit. And there's kind of a lot behind that, but essentially, what we thought was that the damage that's caused by the PARP inhibitors would create an activation of different immuno-pathways, like STING pathway and activating cytokine release, and that we would get this synergistic activity. So one of the other objectives was to see if the addition of the olaparib, the PARP inhibitor, to durvalumab in that maintenance setting could even further improve benefit. So we had a dual primary endpoint looking at progression-free survival, so the amount of time people live without their cancer coming back. And that endpoint was first, the durvalumab-alone arm to control, and then the second portion of that was the durvalumab/olaparib arm back to control.

Dr. Lidia Schapira: So before you tell us about the results, tell us a little bit about the study itself. I mean, I was very impressed that you did it in so many different locations. Tell us about that effort. 

Dr. Shannon Westin: This was a huge collaborative effort both with the GOG Foundation, the Gynecologic Oncology Group Foundation, as well as ENGOT, which is our European colleagues that do amazing clinical trials. But in addition to that, we really worked very closely with our industry partner to really make sure we spanned the globe. And so we had groups from all over the world that participated and really were exceptional. The care that was taken and the hard work that went into this type of study across the world really can't be overstated. We were very lucky to have a wonderful infrastructure group. We met weekly for a long time, just keeping an eye on the data and making sure that everything was as positive as possible and, of course, that we were watching the outcomes of the patients very closely and making sure that there was no evidence of harm or issue. And so it really did take a village, truly, to run this study and to ensure that at the end of it, we got really great data that we can trust.

Dr. Lidia Schapira: So tell us the results.

Dr. Shannon Westin: So DUO-E was positive for both of its primary endpoints, which was very thrilling. So for the first analysis, which is the durva-alone arm to control, we saw a reduction in the risk of progression of 29%, so a hazard ratio of 0.71. And then the addition of olaparib seemed to further enhance this benefit, so a 45% reduction in the risk of progression for a hazard ratio of 0.55. But what's really exciting is our follow-up time was pretty long; it was about 17 months, so we were able to look at a couple of different analyses, including an 18-month landmark analysis where we saw approximately 50% of the patients were still alive progression free at 18 months, as compared to only 21% of patients being alive progression free in the control arm. So there was a doubling in that progression-free survival time point at 18 months, which is thrilling.

Dr. Lidia Schapira: So Ramez, as an expert in the field, what was your reaction when you read or heard these results? 

Dr. Ramez Eskander: It's exciting, honestly. So we have gone a long time without seeing really significant successes in the endometrial cancer space, a testament to the fact that we hadn't yet developed our understanding of how we could move this needle forward. But Dr. Westin and the DUO-E team conducted an exceptional clinical trial, as you mentioned, international study, rational and important hypothesis to adjudicate. And what we saw here was both now we had other studies—the RUBY trial, the GY018 trial, the  AtTEnd—and now here DUO-E, which added this hypothesis of PARP maintenance in addition to checkpoint to try to augment response and consistent, really provocative data, exciting, in line with what we've seen and hopefully will continue to drive the science in this space, most importantly.

Dr. Lidia Schapira: So let me ask you a follow-up question to that. What kind of scientific questions are in the air now as a result of this trial and what the trial found?

Dr. Ramez Eskander: Oh, goodness. Shannon and I could both take this, I'm sure. But I think in the dMMR population, we recognize that there's a ton of data that is supportive of the fact that these tumors are immune responsive, particularly in dMMR endometrial cancer, whether it's an epigenetic promoter hypermethylation, or a mismatch repair gene mutation. I think the data has emerged that immunotherapy is here to stay for these patients in the newly diagnosed advanced stage, even chemo naïve, who need adjuvant therapy.  

The pMMR population, this is where we're seeing more and more questions emerge because we realize that that may be a cohort of different cancers. And I'll let Shannon speak to this briefly, but even the incorporation of the PARP inhibitor, in addition to the checkpoint, there's a biologic rationale for combining those two together to augment response. And to see the benefit in that trial—arm three and arm two, we can look at descriptively and look at the differences, but who are those patients? Where is the PARP and the checkpoint most effective? How do we expand that to a larger population of patients potentially? These are questions that emerged because, as Dr. Weston will allude to, I know we also talk about HRR mutations, which are captured, but we even have a lot to understand about that in endometrial cancer, where we've had more research in the ovarian cancer space.

Dr. Shannon Westin: Being mindful of time, because I have, like, 1,000 hypotheses that have been generated by this study, which, I think, shows it's a great study, right? Because you get some answers, and as our colleague Brad Monk says, “The only definitive study is the negative studies.” This most certainly was not that. But just kind of expanding on what Ramez said, the interesting thing about DUO-E is that really the biggest benefit for the combination of the durvalumab and olaparib was in that mismatch repair proficient group. And I personally thought that we were going to see accentuation of the impact in the mismatch repair deficient group based on the science, but that just wasn't borne out by the data. It doesn't seem that the combination has that much to add in that mismatch repair deficient group. And when we tease out the mismatch repair proficient group, I think that's where a lot of interesting information is going to come because, to Ramez's point, we're going to tease out: Is it driven by the P53-mutant population? Is it driven by the population that has homologous recombination deficiency? How do we even measure homologous recombination deficiency in endometrial cancer? So I'm super excited about what we found and how that may help us to make those decisions for the patient in front of us. 

The other thing I think needs to be made mention of—and this was something we saw in DUO-E as well as AtTEnd—we had a large population of patients that were recruited in Asia, 30%. Interestingly, when we look at the forest plot, that group doesn't seem to benefit as much from the addition of the olaparib. So we really need to tease out what's different about that population because what Nicoletta Colombo presented around AtTEnd, it looked like they didn't benefit from the atezolizumab either in that study. So there's clearly something different about that population, and we have a really big opportunity to look at that since we had such a large proportion of patients that were enrolled there. So that's another, I think, really intriguing question.

Dr. Lidia Schapira: So how does this fit in the context of endometrial cancer treatment, and what are we going to do with patients in the clinic? I'd love to hear both of your perspectives, starting with you, Ramez.

Dr. Ramez Eskander: It's an evolving answer, to say the least. What we can say definitively is that we have a United States FDA approval for the regimen of dostarlimab plus carboplatin and paclitaxel in the mismatch repair deficient, advanced-stage/recurrent or metastatic patient cohort. And again, that's because the magnitude of benefit that we saw in the RUBY trial, which looked at that, was actually analogous to what we saw in 018, AtTEnd, and DUO-E, again, consistently highlighting the benefit of the IO and the dMMR. We have yet to see how this is going to evolve the landscape in the larger patient population, which is the pMMR patient population. And it may be that based on the data that we have, we will see immunotherapy plus carboplatin and paclitaxel as the new standard of care in the pMMR cohort, or it may not. That's yet to be defined. And I think Dr. Westin will add to this, but I think that's also going to depend on the perception of how we view the cohort. Is it one group of patients? Are we going to have to think about subsets within the pMMR population? That is an active conversation.

Dr. Shannon Westin: I would just add, having treated patients on this combo regimen with the durvalumab and olaparib, I have multiple patients that still remain on study, and this—we're looking at three and four years out. I just never saw anything like that before with standard chemotherapy, so there's definitely something here. So I want to know who those patients are, who benefits really the best from the combination, and who could we just give the immunotherapy to and get that same benefit. So we obviously always want people to live as long as possible. That's the bottom line. But we don't want to overtreat. And so I think balancing that is really important.

Dr. Ramez Eskander: The point that was made earlier: We have yet, aside from MMR response to checkpoint, within the pMMR population, we understand that there may be subsets, but we have yet to prospectively validate that these molecular cohorts within the pMMR population are truly defining response to a particular therapeutic strategy. So we have to be cautious not to limit the treatment opportunities for these patients without having the data that we need to do so because, as Dr. Westin mentioned, for us—whether it was the Gy018 trial, the RUBY, the DUO-E trial—what we saw is there are pMMR patients who have a dramatic response even though they are “biomarker negative.” They're pMMR, they're TMB low, they're not POLE mutated, but yet they still derive a dramatic benefit. And so that goes back to the hypothesis about why we're even combining checkpoint with chemotherapy in which, for example, in lung cancer, there's been established success and approval. So I think we're all eager to see these strategies emerge as treatment opportunities for the pMMR patients as we work to still develop additional effective opportunities.

Dr. Lidia Schapira: So, based on all of this and sort of the new twists on the scientific hypotheses that are now generated, what are the next steps?

Dr. Shannon Westin: Well, I think we have to see if these drugs are available for patients. So looking at things like compendium listing and regulatory approvals obviously is going to be very important. But from the things that I can control, we are looking at the different molecular subtypes and understanding the different mutation status and trying to tease out who may be driving the biggest benefits so that we can help advise and make sure that we're doing the right thing for the patients.

Dr. Lidia Schapira: And wearing my supportive care hat, I have to ask you, Shannon, about the tolerability. We often find that the quality of life and studies come out after, sometimes months or years after, the original trials are published. So let me take this opportunity to ask you now: How did women tolerate these drugs?

Dr. Shannon Westin: The bottom line, Lidia, is, as expected, when you add additional drugs, you see additional side-effects. I think the good thing is that we're very comfortable with immunotherapy and we're very comfortable with PARP inhibition in gynecology because we have had access to these agents and so we know how to manage the toxicities. And so, from a standpoint of incidence, there was a higher incidence of grade three and higher adverse events in the group that had durvalumab/olaparib. But this was primarily driven by anemia, which is as expected and is usually pretty time-limited at the start of olaparib. From a long-term standpoint, there was a slightly higher proportion of patients that discontinued therapy, but it actually wasn't as much as I was worried about. So we saw a 19% discontinuation rate in the group that was just the control arm, and that went up to 24% in the dual arm, so definitely higher, but not that much higher. And when we moved to maintenance, which is really where—that's where the arm becomes unique, it was much lower at about 12%. And so that's exciting to me, that patients were able to stay on a drug and were able to tolerate it. 

And then, to your other point, we do have a very nice patient-reported outcomes plan, and that is actually being analyzed as we speak with the hope of presenting it at the next major meeting, our Society of GYN Oncology meeting in March. So not right away, but I think in a pretty timely fashion, we'll have those data.

Dr. Lidia Schapira: Congratulations, Shannon, on leading and presenting this wonderful study. So it's been a real pleasure to chat with the two of you.

Dr. Ramez Eskander: Thank you.

Dr. Shannon Westin: Thanks so much, Lidia. I really appreciate it. Thanks, Ramez, for being here. 

And I will just say thank you to all of our listeners. We really hope you enjoyed this episode of JCO After Hours, where we discussed the DUO-E trial, which is a phase III trial evaluating durvalumab plus carboplatin/paclitaxel followed by maintenance durvalumab with or without olaparib as first-line treatment for advanced endometrial cancer. And again, please do enjoy this publication that was online at the Journal of Clinical Oncology on October 21st, 2023. And do check out our other podcast offerings wherever you get your podcasts. Have a wonderful day.

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