Shernan Holtan, MD, Associate Professor of Medicine, University of Minnesota, Minneapolis, overviews a phase 2 study on human chorionic gonadotropin and epidermal growth factor as treatment for patients with acute graft-versus-host-disease (aGVHD). Dr Holtan also highlights a secondary analysis of 2 prospective clinical trials on the validation of amphiregulin as a monitoring biomarker during aGVHD treatment. These data were presented at the 2021 American Society of Hematology (ASH) Annual Meeting.

Transcript

Hi. My name is Shernan Holtan. I'm an associate professor of medicine at the University of Minnesota.

Our research came out of an unmet need. During my training and junior faculty years, I observed a lot of loss of life due to severe graft-versus-host disease (GVHD), especially gastrointestinal GVHD.

I recognized that what we were doing in terms of increasing immunosuppression was not always working. It seemed that we needed to do something to help the intestine repair and help facilitate immune tolerance as opposed to immune suppression. Thinking about changing that paradigm, I wondered how we could feasibly approach this.

The concept of this study came to me when I was pregnant for the first time. I realized when I was a fellow carrying my first child that this is a setting where I have immunologic tolerance towards this baby. There's no bad immune reaction going on, yet he doesn't match me. Why is it that patients go through a matched transplant and have horrible complications?

This concept of immune tolerance in pregnancy is what led me to try to use pregnancy hormones to induce immune tolerance in GVHD. There was an added benefit with it. We found that a commercially available preparation of the primary hormone in pregnancy that induces immune tolerance, which is human chorionic gonadotropin. A commercially available preparation of that also contained high levels of epidermal growth factor, which is a hormone that can help repair tissues after damage.

We thought, "This is pretty amazing. We have a cheap, commercially available drug that we could use to help support immune tolerance as opposed to suppression and give a hormone to help with tissue repair as well."

With this study, we enrolled patients with life-threatening acute GVHD. This is critical. If we enroll patients who have mild GVHD, it would be tough to see a signal of efficacy because these patients are expected to do well with steroids alone. We focused on those who had a high risk of mortality. We had 2 arms of the study, first-line treatment with Minnesota high-risk acute GVHD. These are newly diagnosed patient with acute GVHD who have a high likelihood of death due to the complication.

The second arm of the study where patients with established GVHD who either had a flare of GVHD after immunosuppression taper or were considered steroid-refractory, meaning the first-line therapies were not working for them.

What we did is we took these 2 types of patients and gave the human chorionic gonadotropin and epidermal growth factor as a supplement to standard-of-care immunosuppression.

In the first-line setting, patients were receiving high-dose steroids as a part of their standard of care.

In the second-line setting, it was physician's choice, so either a higher dose of steroids or a second-line agent, such as ATG.

In the era during which we were enrolling patients, ruxolitinib became FDA-approved for steroid-refractory GVHD. This was an allowed concomitant therapy as well on the second-line arm.

It was very simple. We just gave this hormone supplement subcutaneously in conjunction with standard-of-care immunosuppression and monitored outcomes.

The primary endpoint of the study was day-28 response, either complete (CR) or partial response (PR).

Overall, in the study, 68 percent of patients had a CR or PR, which is significantly better than our experience historically.

The outcomes were very hopeful. We gave the supplement and wanted to see if we were making progress in terms of the response rates. Something that we couldn't have quite anticipated was how much better people felt quickly. Even before GVHD scoring was significantly changed, for example, we noticed that people seemed to have a better sense of wellbeing. I have no score for this. We, unfortunately, didn't do quality-of-life surveys.

What I think we were observing was the anabolic effect of the drug. We noticed on our study that patients who started taking this medication had a significant increase in their testosterone levels. That is a known side effect of this drug.

In fact, some bodybuilders take this drug, not by recommendation of any physician—I have to be honest, don't do this for bodybuilding. It is known in the field that this had anabolic effects. Amazingly, we were seeing that with our patients with a greater sense of wellbeing, a greater sense of appetite, more energy even before their GVHD was improving.

I have to say we were focusing on immune tolerance and tissue repair, but the anabolic effects were likely significant as well.

There are absolutely real-world implications for this. We hope that this drug will be used to treat life-threatening GVHD today. It's commercially available. It has orphan-drug designation from the FDA. We were able to have the FDA recognize this as a therapy. There's no reason that it can't be prescribed by physicians now. The reason this was so important to us is we lacked other regenerative medicine tools over the past several years in GVHD.

We have clinical trials for MSC therapy, or other cytokines or growth factors, or other cell-based tissue regeneration platforms, but those are all in the context of trials. If you don't happen to have a study available at your institution, you don't have that option.

This is a drug that's already available. You can purchase it. It has the FDA orphan-drug designation. I have been able to get it covered by insurance because of that. There's no reason that this can't be used today.

A word of caution, if people do use this medication, please, take a look at the entry criteria for the study. I would suggest that people would adhere to the same types of guidelines. Use for life-threatening acute GVHD, especially GI GVHD. Patients had to have adequate renal function. They had to have adequate heart function. The reason is there can be some fluid retention with this medication. There is a theoretical risk of increase in thrombosis risk as well. We did not allow patients who had recent thrombosis within 3 months on study.

Within those caveats, I would hope that people would consider this as a supportive care for severe GVHD today.

Yes, we're absolutely expanding upon this. Our hope is to eventually make treatment for life-threatening GVHD more efficacious as well as easier to tolerate.

As you know, the historical treatments have been high-dose steroids which come with a myriad of side effects including metabolic problems, high blood sugar, high cholesterol, bone loss, loss of muscle tissue, myopathy, insomnia, the list goes on. It's a difficult therapy to receive. The other options that we have are highly immunosuppressive. Those open the door to infections.

What we'll be doing is using human chorionic gonadotropin with a multimodal therapy to see if we can provide adequate immunosuppression, but not excessive immunosuppression, along with supportive care including this medication to try to make the treatment very effective but also have fewer side effects to overall improve the response rates and improve quality of life for patients.

The unmet need we are trying to address is a way to monitor response in GVHD. Currently, we rely on patient-reported symptoms as well as some laboratory values and clinical signs that can have a lot of variability. This is particularly true when we're trying to assess response in GI GVHD.

The primary way that we measure response is frequency of diarrheal output. If someone is in the hospital, we can be pretty accurate, but if someone is not in the hospital, how do you measure? It's very challenging to do so. Patient recall is challenging. They're sick. They don't feel well. The last thing they want to do is record the number of times and the volume of stool that they go every single day, especially if this is going on for days to weeks.

We wanted to try to develop a biomarker that could help us assess our progress during the course of GVHD therapy. There are a number of good biomarkers that can help risk-stratify patients at the onset of GVHD.

To date, there's been no monitoring biomarker that we can measure frequently that would be similar to measuring a creatinine as an estimate of kidney function. What we're trying to do is develop something that we can use to monitor frequently along the way that has more objectivity to help us guide our therapies.

We tested the biomarker amphiregulin as a monitoring biomarker in our clinical trial of human chorionic gonadotropin for life-threatening acute GVHD. We used this based upon our preliminary data showing that amphiregulin was associated with clinical response and survival in acute GVHD.

Now, we're taking it forward, and monitoring it frequently throughout the course of therapy, and watching the trajectories over time.

We found that amphiregulin significantly decreases over time in patients who have a response to therapy. It starts high. As patients improve and durably so, amphiregulin levels come down and stay down.

To validate that observation, we also performed a similar analysis on samples from the REACH1 study that was ruxolitinib for steroid-refractory acute GVHD. We wanted to see, is the pattern the same where patients start therapy and have a high amphiregulin and it comes down over time in responders? Indeed, we did see the same pattern in that separate clinical trial as well.

There's another unique feature of this particular study is that we measured amphiregulin on different platforms with the 2 different clinical trials. With our study at the University of Minnesota, we measured amphiregulin using an ELISA in our hospital's cytokine reference laboratory. With the REACH1 samples, amphiregulin was measured using a microfluidics assay.

Regardless, even though the methodologies were different, we saw the same pattern. What we hope this gives is flexibility for hospital systems to be able to choose the platform that may work best for them. We want testing to be done in-house with whatever platform they are used to using. This gives confidence that if it's ELISA or microfluidics, you can use either one, just measure it consistently throughout the course of therapy.

We are looking at continuing to study monitoring graft-versus-host disease activity with amphiregulin. We want to use this and see if it can have as much relevance as clinical symptoms—we think it will. When we're measuring clinical response, it's really challenging if someone develops an infection or medication side effect. Those symptoms can mimic flares of GVHD.

We hope that we can use amphiregulin to give us confidence that even though symptoms may be worse, it's not related to GVHD, and continue on your treatment path, versus wondering if you need to increase immunosuppression.

We need more real-world data about this. We've got this validated now in 2 independent clinical trials. It's time to start testing this in the real world as we monitor patients and see if this really works. What we don't know yet is to what degree other post-transplant complications may elevate amphiregulin levels. If infections develop or other unforeseen complications, could that alter our results? We don't know since we've only tested this in the context of 2 prospective studies. We do hope to use this in the real world and understand how it can be applied.

We will be testing longitudinal amphiregulin levels in the context of other clinical trials as well as some stored samples that we have. We will continue to work to see if this could be a creatinine for GVHD, something that we can monitor frequently to help gauge responsiveness. This is ongoing work. It will take some time, probably another couple of years before we know if there are other factors that influence amphiregulin levels.

The other thing that we don't quite know yet, although we have some ideas, is where is all this amphiregulin coming from? We don't know the source of it fully in every patient. We do know that it can be expressed in tissues including the GI tract. Its expression can be altered during GVHD. It can be expressed in the skin during GVHD. We have a gene expression study showing its increased expression in circulating peripheral blood mononuclear cells in GVHD.

The thing that would be nice to know is exactly who is responsible for the amphiregulin elevation? What are the cells, and understanding the mechanism of that to a greater detail? Over the next few years, we'll be sorting that out. Then we'll know, in real time, what we're looking at as we're using this as a monitoring biomarker.

I appreciate the chance to share our data and our stories. What our group has been looking for are practical solutions to life-threatening graft-versus-host disease. We wanted something that we can use today to help improve outcomes while the science is still ongoing and while the work from many laboratories is being translated to clinical trials.

One other thing that I wanted to share is this is a homegrown effort. Our work with the clinical trial to use human chorionic gonadotropin in life-threatening GVHD was not supported by any pharmaceutical company. This is something that we were able to do because of the support of grateful patients. Seriously, a grateful family donated the money for us to start the study. We were able to obtain a grant from Regenerative Medicine Minnesota to continue it.

Because this is a commercially available, inexpensive drug, that's a problem in a way for conducting clinical trials, honestly. There was not pharmaceutical industry support.

Same thing with the biomarker. This is something that is homegrown here. We've started from scratch. We've done this ourselves.

I'm extremely proud of that.

It's not to say that drug-company-sponsored research isn't good. It's a pretty heavy lift to do things without that support. I'm extremely proud of our team and our program for getting these studies done.