In this JCO Precision Oncology Conversations podcast, JCO PO author Dr. Thanh Dellinger of City of Hope National Medical Center shares insights into the research published in her article, “Hyperthermic Intraperitoneal Chemotherapy–Induced Molecular Changes in Humans Validate Preclinical Data in Ovarian Cancer.” Podcast host Dr. Abdul Rafeh Naqash talks with Dr. Dellinger about hyperthermic intraperitoneal chemotherapy (HIPEC) and the various challenges of the treatment of epithelial ovarian cancer (EOC). The study described in this JCO PO article discusses protein expression, RNAseq alterations and signature, and whole-transcriptome sequencing and signatures. Read here  https://ascopubs.org/doi/full/10.1200/PO.21.00239

TRANSCRIPT

Dr. Abdul Rafeh Naqash: Welcome to ASCO’s Precision Oncology Conversations where we bring you the highlights and overview of precision oncology. This podcast is here to provide interactive dialogue focusing on the excellent research published in the JCO Precision Oncology.

Our episodes will feature engaging conversations regarding precision oncology with the authors of a clinically relevant and highly significant JCO Precision Oncology article. You can find all our shows including this one at asco.org/podcasts, or wherever you get your podcasts.

Hello, I am Dr. Abdul Rafeh Naqash. I’m a medical oncologist and a phase one clinical trialist at the OU Stephenson Cancer Center. You're listening to JCO Precision Oncology Conversations.

I have no conflicts of interest related to this podcast. A complete list of disclosures is available at the end of each episode.

Today, I will be talking with Dr. Thanh Dellinger from the City of Hope Comprehensive Cancer Center, who's a gynecological oncologist, and we'll be talking about her JCO Precision Oncology article, ‘Hyperthermic Intraperitoneal Chemotherapy-Induced Molecular Changes in Humans Validate Preclinical Data in Ovarian Cancer.’

Dr. Dellinger does not have any conflicts of interest.

Hi, Dr. Dellinger, welcome to our podcast!

Dr. Thanh Dellinger: Hi, Dr. Naqash! It’s such a pleasure to be on with you.

Dr. Abdul Rafeh Naqash: We recently saw your paper published. It's one of those interesting, clinical translational papers that we felt needed to be highlighted in our Precision Oncology Podcast series.

So, we're really excited to have you here today to take a deeper dive into the findings and some of the novel approaches that you used in your recent publication. So, for starters, could you give our listeners a brief idea of what HIPEC is, where it's used, and when it's used in ovarian cancer?

Dr. Thanh Dellinger: Right! Thank you very much for this great introduction. So, HIPEC or Hyperthermic Intraperitoneal Chemotherapy has been used in ovarian cancer for quite some time.

The most relevant data giving us an indication for ovarian cancer was published by Dr. van Driel in the OVHIPEC-1 randomized trial several years ago in the New England Journal of Medicine, which demonstrated that in stage 3 ovarian cancer patients who undergo an interval tumor debulking with HIPEC, that those patients appear to enjoy both progression-free and overall survival benefit. In fact, the overall survival benefit is nearly 12 months for those patients.

So, with this in mind and a number of other data, the HIPEC treatment for those patients that interval debulking has been incorporated into the NCCN guidelines. Nonetheless, there have been some criticisms of HIPEC and it still remains to be seen who those patients are, the ovarian cancer patients who really best benefit from HIPEC, given the morbidity of HIPEC. We now know also that HIPEC is probably equivalent to just cytoreductive surgery alone in terms of morbidity.

Dr. Abdul Rafeh Naqash: Thank you for that explanation. And especially for people like myself, who are not surgeons or gynecological oncologists, that was very helpful. So, my next question, and you probably partly answered it, but I'm going to still ask the question is: what is the reason you think that intraperitoneal chemotherapy overall, has not been as widely adopted?

Dr. Thanh Dellinger: You touch on a very good point there. As many of the listeners may understand, IP chemotherapy has demonstrated a lot of efficacies in multiple clinical trials over the last decade or two decades even.

And part of why, despite its benefit, it has not been taken up in the overall community may really be the difficulty and the complexity of doing IP chemotherapy in the community, especially the side effects are difficult sometimes to take care of. There's increased abdominal pain and there are catheter issues.

And so, especially with more recent data, that with the presence of Avastin, IP chemotherapy may not necessarily be as beneficial. Unfortunately, IP chemotherapy hasn't been really taken up in daily oncologic care with ovarian cancer.

Nonetheless, we know that there are a lot of theoretical benefits because of the peritoneal metastasis not being as best treated with intravenous chemotherapy as with regional therapy.

Dr. Abdul Rafeh Naqash: Thank you! So, now going to the data that you published. I was very intrigued with some of the findings. And from what I understood, your main aim was to understand predictive biomarkers to identify patients or basically identify molecular characteristics for patients' selection for HIPEC.

So, could you tell us more about why you initiated this study? And I understand this is one of the, I believe the first study in humans to evaluate some of these interesting biomarkers, both pre- and post-. So, what was the background of doing this trial? And what led to this interesting study?

Dr. Thanh Dellinger: Thank you for pointing out this aim. There's a lot of criticism of HIPEC and part of it is that we may not exactly understand the mechanisms of HIPEC, why is it that it works so well in some patients?

There's a lot of preclinical data supporting hyperthermia, especially with cisplatin. There's synergy between cisplatin and hyperthermia, and improving the DNA adduct formation. There's increased cytotoxicity seen when the temperature increases up to 43 degrees. And there's also a T-cell activation and immune response that occurs during hyperthermia.

So, a lot of this, however, has been done in preclinical studies, in vitro data as well as preclinical mouse models. There hasn't been much or really anything published that, as far as I know, has been done in humans.

And so, this particular study looked at both pre-treatments, pre-HIPEC specimens, peritoneal biopsies, as well as immediate post-operative peritoneal biopsies, tumors, and normal samples, and we wanted to look both at the whole transcriptomic sequencing profile, but also at the tumor microenvironment.

Dr. Abdul Rafeh Naqash: From a logistic standpoint, from a trial design standpoint, was this a phase 1 study? I know you use the term pilot in the publication. So, were you trying to look at safety also, or was this primarily I would say, a biomarker, pharmacodynamic biomarker-driven study that you were trying to evaluate?

Dr. Thanh Dellinger: You're correct. This was essentially a feasibility study. But we additionally looked at safety and feasibility with HIPEC at our institution. And in some respects, we also looked at the feasibility of giving intraperitoneal chemotherapy normothermically early after HIPEC, and so it was also an endpoint to look at safety.

Dr. Abdul Rafeh Naqash: Understand! I believe there was some difference in the dose for the cisplatin, I believe, is the chemotherapy that you use. What was the rationale for the difference in the dose for 75 milligrams per meter square that you use in your study?

Dr. Thanh Dellinger: The study was initiated at a time before the OVHIPEC-1 trial was published. And so, at that time, the HIPEC dose for cisplatin was still not established. 75 milligrams per meter square for cisplatin was actually used in other trials, and has been noted to be effective in other clinical trials.

Dr. Abdul Rafeh Naqash: Thank you! Now going to the patient population for this trial. What type of patients were you enrolling? Was it just epithelial ovarian cancer patients, did these patients need to have peritoneal metastases when you were doing this cytoreductive surgery? What was the patient population that you were targeting in this trial?

Dr. Thanh Dellinger: The majority of the patients did have epithelial ovarian cancer. We did enroll a few, actually 5, uterine cancer patients as well, which were not included in this specific publication. But the majority of them were epithelial ovarian cancer patients.

Dr. Abdul Rafeh Naqash: Going to the interesting translational analysis. So, you had three subsets of patients based on the biopsy collection. What were your hypotheses, and what drove some of those translational studies to understand the biomarkers?

Dr. Thanh Dellinger: The first translational analysis we conducted was the whole transcriptomic sequencing, and specifically, we wanted to look, one, for any potential transcriptomic signatures that may correlate with survival or improved response to HIPEC.

The second one was to look at whole exome sequencing. Thirdly, we looked at whole transcriptomic sequencing differences before and after HIPEC treatment. And lastly, we looked at the tumor microenvironment through multiplexing of certain markers associated with T-cell response.

Dr. Abdul Rafeh Naqash: From a clinical outcome standpoint - and we'll discuss the biomarkers in more detail - from a clinical standpoint, when I briefly looked over the PFS curves, were the results, as far as expected outcomes, were they similar to what you see with the current standard? Or were there any unusual safety signals? Or would you attribute any of the adverse events that you saw to intraperitoneal chemotherapy specifically? Because I believe some patients did have some chemotherapy pre-surgery, neoadjuvant if I'm correct. So, how would you attribute some of those AEs, and if at all, did you see any interesting safety signals of concern and outcomes as far as PFS is concerned?

Dr. Thanh Dellinger: So, one of the major toxicities that we saw in the first half of our trial were actually renal toxicities. In fact, there were actually two patients who could not go on to adjuvant chemotherapy because they suffered chronic renal failure.

And because of that, halfway through the trial, we did actually add a nephro protectant called sodium thiosulfate. And this actually dramatically improved those renal toxicities. And for the second half of our study, no patients suffered grade three or grade four renal adverse events. And so, that did change significantly.

Dr. Abdul Rafeh Naqash: From a genomic standpoint, it's very interesting that you were able to do all these very cool and interesting translational biomarker studies, including multiplex immunofluorescence.

From a genomic standpoint, though, would you say it's fair to say that there was no significant correlation based on the baseline genomics for some of the patients and their outcomes? Is that a fair assessment?

Dr. Thanh Dellinger: Yes, that is a very fair assessment. I think that our cohort was really too small to make those kinds of assessments. I don't know whether you saw there recently was a paper published by the OVHIPEC-1 group looking at their cohort of over 200 patients that underwent the interval cytoreductive surgery in HIPEC and they did actually demonstrate benefit in patients who are HIV-positive but BRCA wild-type, but not necessarily in BRCA mutated patients. So, I think that I would point to that study to look for genomic effects with HIPEC patients.

Dr. Abdul Rafeh Naqash: Understand. Now, again, going to the biomarkers that your team evaluated, it seems from among good responders especially, you saw an increase in tumor necrosis factor, alpha signaling, NF-kappa B signaling, KRAS signaling, and then you also saw some pathways that were downregulated, especially the G2-M checkpoint, and Myc targets. What would you say the correlation of these is in terms of future drug development in this specific setting?

Dr. Thanh Dellinger: I think that we did see some increase in immune pathways in patients who did better in the end. And also, our multiplex results did demonstrate that E1 expression was increased in patients who had better responses after HIPEC.

So, our hypothesis is that potentially, there's an activation of T-cell response with HIPEC and that potentially PD-1 inhibitor could be added in the future. This is a hypothesis that certainly would need to have more work, but it's something that is interesting enough to really look at in ways of how to improve HIPEC.

Dr. Abdul Rafeh Naqash: Going to your point on the PD-1, I found really intriguing that you were able to see an increase in PD-1 expression on CD8+ T cells but no actual increase in the number of CD8+ T cells suggesting there's some sort of activation of this marker and this may not necessarily be a marker for T-cell exhaustion.

So, would you interpret it in a way that in a different setting, perhaps a new adjuvant approach with immunotherapy, would perhaps somehow augment this and then you could see more upregulation? Is there any work being done in that field? How would you put this in the context of your findings?

Dr. Thanh Dellinger: You bring up a really great point because to date HIPEC has been demonstrated to have benefit in the interval setting. But there was a more recent study done by, well not recent, a more recently published study by a Korean group that demonstrated no benefit in the adjuvant setting for HIPEC and still some benefit in the interval setting.

And the question is, are these really two different types of cohorts who respond differently because of potential differences in immune response and tumor microenvironment? I think that that would be a great way of delving further into this. What are really the differences in tumor microenvironment changes in those two different settings?

Dr. Abdul Rafeh Naqash: Definitely! It’s very exciting. You've also shown upregulation of, as you mentioned earlier, immune pathways, as well as upregulation of genes related to heat shock proteins. Does that play into future drug development as far as HSP Inhibitors are concerned?

Dr. Thanh Dellinger: That is a really great question. Certainly, in preclinical models, heat shock proteins are known to be elevated and they do activate dendritic cells and result in T-cell activation.

Now, whether that can be spelled out into actually some future drug therapy definitely remains to be seen. To date, there hasn't been any success in using heat shock types of agents or inhibitors, unfortunately. So, I think while this is of great interest, I'm not entirely sure that this will translate into any drug therapy in the future.

Dr. Abdul Rafeh Naqash: And I totally connect with you there as a phase 1 trialist. I completely agree that we see a lot of translational data, more often than not, going into the phase 1 site because many of these targets are not actionable.

Now, from a DNA repair standpoint, you did see that there was interference with DNA repair, as far as some of the analyses that you did, but I did not specifically see any markers for DNA damage that were assessed on the biopsies such as Gamma-H2AX, RAD 51, or Phospho-NBS. Was there a reason why that was not looked at?

Dr. Thanh Dellinger: I think that we did look at that and there weren't really any significant results. We did put some of the data into the supplementary data. I think that in the end, our cohort was really too small to really make any meaningful data. But I absolutely agree with you looking at HSP and DNA repair is really important. And as I mentioned that most recently published paper does address that.

Dr. Abdul Rafeh Naqash: Excellent! Do you think that there could be any confounders in this analysis that could have led to the upregulation of some of these pathways and may not necessarily have been the intraperitoneal chemotherapy?

Could you think of some other reasons that this could have been a confounding factor? Or would it primarily be attributed to the intraperitoneal chemotherapy that you guys have looked at in this interesting paper?

Dr. Thanh Dellinger: Yeah, it is a rather small cohort. So, I think that more data is required to potentially repeat this in the larger cohort. But what is interesting is that we did have paired analysis.

So, we had matched peritoneal samples from the same patients looking before the HIPEC and after the HIPEC, which is very unique and hasn't really been done in the setting before. And while you couldn't necessarily repeat the same exact peritoneal tumor it was very close. And so, in the best setting, I think that we did have a good paired analysis.

Dr. Abdul Rafeh Naqash: That was one of the very interesting aspects of this study that I very much appreciated, that you were able to get some of those paired biopsies and do the analyses on samples and look at all these markers.

So, this was all excellent work and definitely intrigues the mind into what other ways one could use some of these findings to develop future combination-based approaches, whether it's the neoadjuvant or the adjuvant setting for patients with ovarian cancer. Are there any next steps as part of this project that you are excited about that you can share?

Dr. Thanh Dellinger: Right! I'm definitely very excited about trying to build on this and essentially developing a much larger predictive study using hundreds of ovarian cancer HIPEC-treated tumors in collaboration with others.

We have definitely developed a great community of HIPEC investigators who are very interested in developing somewhat of a predictive signature for ovarian cancer undergoing HIPEC.

So, I’m very excited to hopefully be able to develop this consortium of HIPEC transcriptomic research. And so, I’m looking forward to collaborating with my co-investigators on that.

Dr. Abdul Rafeh Naqash: It was definitely exciting to talk to you about your work. Now, I want to ask you about you as an investigator or as a researcher. How did you end up in this field? What was your background while you were pursuing science and medicine? How did you end up in this field and how are you mentoring the next generation?

Dr. Thanh Dellinger: When I was a fellow at UCI, my mentor Robert Bristow introduced me to HIPEC and that has really stuck. As a GYN oncologist, it is hard to really do both chemo and be a good surgeon. And in many ways, I have really specialized in surgical oncology more than in medical oncology. And HIPEC is really a very nice blend of the two.

It allows you to do clinical trials while still doing surgery and giving some chemotherapy. Really, it was for the introduction of my more recent mentor, Elena Rodriguez, who really introduced me to genomics and applying this to HIPEC samples that this all came about.

And so, I think that there are a lot of opportunities for surgical oncologists who do not give chemo and may think that clinical research is not for them, but there are a lot of translational opportunities and clinical trial opportunities for those who don't give chemotherapy, but are surgical oncologists.

Dr. Abdul Rafeh Naqash: Thank you so much. We are really excited for all the work that you're doing and will continue to do and hopefully, we'll see more of this evolve as time progresses.

Dr. Thanh Dellinger: Thank you so much, Dr. Naqash. It was such a pleasure meeting you and talking to you.

Dr. Abdul Rafeh Naqash: Same here. Thank you for listening to JCO Precision Oncology Conversations. To listen to more, visit asco.org/podcasts, or find them on Google Play Spotify and Apple podcasts.

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Guest Bio

Dr. Thanh Dellinger, MD, is a gynecologic oncologist and physician-scientist who specializes in ovarian and uterine cancer. She is an expert in hyperthermic (HIPEC) and pressurized aerosolized intraperitoneal chemotherapy (PIPAC), and is the primary investigator of clinical and translational studies focusing on these therapies. She received her medical degree at University of California Irvine, where she also completed a gynecologic oncology fellowship. She is leading the first U.S. clinical trial in PIPAC (pressurized intraperitoneal aerosolized chemotherapy), a novel therapy using pressurized aerosolized chemotherapy for ovarian cancer. Her current research focuses on innovative therapies for ovarian cancer using intraoperative chemotherapy, and novel antibody and nanoparticle therapies.

Hyperthermic Intraperitoneal Chemotherapy–Induced Molecular Changes in Humans Validate Preclinical Data in Ovarian Cancer with Dr. Thanh Dellinger

JCO Precision Oncology Conversations