Activity Transcript

Steven L. Flamm, MD, FACG, AGAF: Hello, I'm Dr Steven Flamm, professor of medicine and the director of clinical research in hepatology at the Rush University Medical Center in Chicago. I'd like to welcome you to this Medscape program entitled, "A Spotlight on Emerging Treatments for Primary Biliary Cholangitis." I'm very pleased today to be joined by 2 nationally known panelists, Dr Raza Malik, chief of the Division of Gastroenterology and Hepatology, and the vice chair of the Department of Medicine at Albany Medical College in Albany, New York; and Dr Atoosa Rabiee, chief of transplant services and director of hepatology, assistant professor of medicine at the VA Medical Center in Washington, DC. Welcome, Raza and Atoosa.

Raza Malik, MD, PhD: Thank you.

Dr Flamm: Today, we're going to be discussing emerging treatments for primary biliary cholangitis. It's a very exciting time in the treatment of PBC. Many therapies that are new are in development that target different aspects of the PBC disease process. Several, in fact, are in late-stage clinical development, though are not yet Food and Drug Administration (FDA) approved. We're going to discuss primary biliary cholangitis in this program in general, how to recognize it, how to diagnose it, and how we treat it today. And then we're going to focus on some of these emerging therapies and how they may be integrated into your clinical practice.

PBC is a chronic cholestatic liver disease thought to be an autoimmune liver disease. It's typically seen in women between their fourth and sixth decades of life. It's considered a rare disease, but it's not really so rare that you won't see it. I would say it's uncommon and if you're a gastroenterologist or hepatologist, you will see patients with PBC. Now, the evidence suggests that the prevalence of PBC may be increasing, and in fact, in 1 study between 2004 and 2014, the prevalence of PBC almost doubled per 100,000 patients observed. Some patients with PBC are asymptomatic. Some aren't destined to progress to advanced liver disease, but many do.

And PBC is characterized by slow progression: first, from a cholestatic liver process without necessarily significant histologic abnormalities in the liver; second, in the end, cirrhosis with its related complications -- such that some patients with PBC, in the end, need liver transplantation. And in patients who progress, the rate of progression is variable. It's become quite clear in recent years that if you don't treat patients for PBC, the risk of progression is greater. Before we get into our discussion about the current therapies and the emerging therapies, Raza, could you please review for us the diagnostic criteria for PBC so a provider can identify patients that have this disease, hopefully, as early as possible.

Dr Malik: Yes. Thank you, Steve. I agree. Before we can treat this important disorder, we have to diagnose it, and the diagnostic criteria for PBC involves having 2 of the 3 criteria per American Association for the Study of Liver Diseases (AASLD) guidelines. The PBC diagnostic criteria include a biochemical evidence of cholestasis -- mainly an elevated alkaline phosphatase level of above 1.5, the upper limit of normal. Or 2, the presence of antimitochondrial antibodies (AMAs) or other PBC-specific autoantibodies on blood testing. Or 3, the evidence of nonsuppurative destructive cholangitis and the destruction of interlobular bile ducts on liver biopsy, what we call a lymphocytic cholangitis, a nonsuppurative type.

Dr Flamm: Thank you, Raza. It's very important. We need to know how to diagnose this. You only need 2 of the 3, Raza. And in fact, back in the old days, since I'm very old now, when we diagnosed a patient with PBC, they often had elevated alkaline phosphatase and AMA positivity, and we still did a diagnostic liver biopsy. We don't do that anymore. If people have 2 of the 3 criteria just mentioned, that alone is enough for the diagnosis of PBC. So, you do not now need to do a liver biopsy if a patient has an elevated ALP and AMA positivity. Now, Atoosa, we know that PBC can be very debilitating for many and that there is a constellation of symptoms and not only hepatic but extrahepatic disorders that are associated with the disease. Could you review some of these for us?

Atoosa Rabiee, MD: Yes, thank you. As you mentioned, most common symptoms of the disease are pruritus and fatigue. Although there are a multitude of extrahepatic manifestations and autoimmune disorders associated with PBC, like systemic sclerosis, sicca syndrome, metabolic bone diseases, thyroid disease, hyperlipidemia, and fat-soluble vitamin deficiency. There are symptoms that are reported by patients with PBC and include restless leg syndrome, bone joint pain, cognitive impairment, or brain fog. And all of these can contribute to impaired quality of life. And as any other liver disease, PBC also can progress to cirrhosis and complications of cirrhosis, such as portal hypertension; variceal hemorrhage; hepatic encephalopathy; and, ultimately, liver cancer.

Dr Flamm: Thank you for that overview, Atoosa. Again, it's very important to diagnose PBC early and treat it as early as possible. So now let's turn our attention to the approved therapies for PBC. There are 2, ursodeoxycholic acid (UDCA) and obeticholic acid (OCA). Atoosa, could you review how these are used?

Dr Rabiee: Our only FDA-approved first-line therapy is UDCA, or ursodeoxycholic acid, with side effects such as gastrointestinal (GI) side effects, hair loss, weight gain. Obeticholic acid was approved in 2016 as second line, and a warning label was then added in 2021, which applies to those with decompensated cirrhosis, prior decompensation events, or those who are compensated but have evidence of portal hypertension. And the main adverse event with obeticholic acid is pruritus.

Dr Flamm: Raza, as Atoosa just described, we have 2 approved therapies for PBC, which of course is great. For many years, there was only 1, but I think you'll agree that there are still some serious limitations with these agents. Could you explain what they are?

Dr Malik: Yes, certainly, Steven. I completely agree with you. We're not in the era of where we were with hepatitis C, or where we are with hepatitis C -- where we've got effective, efficacious, safe treatments and multiple types of treatments -- that we can treat with our underlying disorder. In PBC, there are 2 treatments, but there's still an unmet need for further treatments out there. That includes the fact that we see a lack of biochemical response in 25% to 50% of patients treated with ursodeoxycholic acid. There's an associated greater-than-5-fold increase in risk of progression to cirrhosis and a 3-fold increase in age-adjusted mortality. In these patients, the adverse events (AEs) include hair loss and weight gain. There's not just a risk of progression in liver disease in patients who don't respond to ursodeoxycholic acid, there are also adverse events associated with the medication.

In terms of OCA, or obeticholic acid, currently, it's only a second-line PBC treatment; hence, it's for patients who don't respond for to ursodeoxycholic acid, or in patients who have side effects to ursodeoxycholic acid, and it's the second-line agent. In 2021, the label for OCA was changed so that it could be used in patients with cirrhosis who were well compensated with no portal hypertension. Hence, patients who are decompensated are no longer can candidates for OCA. And this has been shown in the AASLD guidelines. 

Despite good efficacy data, some patients continue to have and discontinue obeticholic acid due to AEs, mainly pruritus. And that's a big issue because we know that pruritus is a major symptom of primary biliary cholangitis itself. So, this causes an additional layer of complexity in patients who have AEs on OCA. In fact, in an Italian PBC registry, 17% of patients discontinued OCA due to adverse events and 66% were due to pruritus. Interestingly, other symptoms of PBC (including fatigue, brain fog) are not alleviated by ursodeoxycholic acid or OCA, creating an unmet need for this symptom group and subspecialty group within the PBC diagnosis.

Dr Flamm: Absolutely, Raza. So clearly there are unmet medical needs for PBC. We do have therapies. It's very encouraging, and in many patients, they're quite helpful. Ursodeoxycholic acid as frontline therapy and obeticholic acid for secondary therapy. But patients don't tolerate some of these medications, number 1. Number 2, they don't work in everybody. And number 3, as you mentioned already, some of the patients are ineligible for these types of therapies such as people with decompensated cirrhosis or even cirrhosis just with portal hypertension.

We need more for patients afflicted with PBC, and that serves as a nice transition to our discussion on emerging agents. As I alluded to in the introduction, there are many different classes of therapies in development for PBC; however, only a few agents are in late-stage clinical trials and we're going to talk about them in depth. The most advanced are the peroxisome proliferator-activated receptor agonists. Atoosa, could you please briefly explain how these agents are thought to work in the context of PBC and its underlying pathophysiology? And then we'll look at some of the specific PPAR agonists that are in development and may be forthcoming for our usage in this disease in the near future. Atoosa?

Dr Rabiee: As a group, PPARs are nuclear receptors. They function as transcription factors, regulating expression of different genes that are involved in metabolic pathways and inflammation. They are basically transcriptional modifiers of bile formation, and regulation of inflammation and fibrosis. There are 3 isoforms: alpha (α), delta (δ), and gamma (γ). PPARα is the predominant one in the liver which regulates bile acid synthesis, phospholipid secretion, and inflammatory pathways. PPARγ and PPARδ have more profound effects on lipid and glucose metabolism, as well as some anti-inflammatory and antifibrotic properties. Fibrates are strong PPARα agonists, although many do have activity against δ and γ. And given that they have anticholestatic effects, they have been evaluated in PBC. There are also nonfibrate PPAR agonists, which are in a late stage of development for PBC.

As a quick summary overview of the different types of PPAR agonists that have been studied in PBC: fenofibrates are PPARα agonists, as I mentioned, and they have been studying in phase 3 randomized control trial (RCT) in those who have had incomplete response to UDCA and with positive results. Bezafibrates or pan-PPAR agonists which, again, are being studied in phase 3 in those patients with inadequate response to UDCA. Elafibranor is a PPARα and -δ agonist, which completed a phase 2 RCT. Seladelpar is a PPARδ agonist, which completed a phase 3. And lastly, saroglitazar is a PPARα and -γ agonist, and the study for phase 2 and phase 3 is still ongoing and estimated to be completed in 2024.

Dr Flamm: Well thank you so much, Atoosa. So, there's a lot of activity in the PBC space. Raza, could you please review the data for us for the 3 PPAR agonists that are the furthest along in development?

Dr Malik: Yes, thank you, Steve. Yes, the PPAR agonists are the furthest along in PBC treatment, and seladelpar in PBC has shown in a randomized phase 3 trial good efficacious results, with 78% of patients at the optimal dose of 10 mg, responding to treatment with a primary composite endpoint at 3 months compared to 12.5% in placebo, which is a significant efficacious response. And if we look at the subgroup with ALP normalization, you can see that 27.3% of patients received ALP normalization, compared to 0% in the placebo group. And corresponding to that, in terms of AEs, the AEs were only mild to moderate. Now moving on to elafibranor in primary biliary cholangitis. Randomized phase 2 studies showed good response rates, again with significant amounts of ALP reduction, ALP normalization, and bilirubin reduction in significant groups of patients.

In the elafibranor in PBC randomized phase 2 study, there was a significant reduction in alkaline phosphatase in both the 80-mg group and the 120-mg group. And there were mostly mild to moderate GI events, fatigue, and headaches, and the events were more significant in the elafibranor 120-mg group. If we look at saroglitazar, the phase 2 study in primary biliary cholangitis, you can again see a reduction in mean change in bilirubin in the treatment group. The optimal treatment group being 2 mg or 4 mg, with the maximum efficacy seen in the 4-mg dose. And biochemical responses were seen in both the groups in terms of efficacy compared to the placebo group, with 65% to 78% efficacy seen at the 2-mg to 4-mg dose, at week 4, week 8, week 12, and week 16 posttreatment. If we look at saroglitazar in the PBC studies and its effects on pruritus at the 4-mg dose, there was a mean change from the baseline and an improvement in itch compared to the 8-mg dose and the placebo dose.

Dr Flamm: Thank you for that review, Raza. The patients enrolled in the clinical trials of seladelpar, elafibranor, and saroglitazar were allowed to continue UCDA throughout the study. Atoosa, this would seem to indicate that these drugs, when approved, will be used as add-on therapy to ursodeoxycholic acid. What are your thoughts about how these novel PPAR agonists will be used in PBC, assuming they are approved? And perhaps you can comment, too, about whether you think they'll ever be used as primary therapy, or only as secondary agents when UCDA fails or isn't tolerated.

Dr Rabiee: Although I suspect ursodeoxycholic acid (urso) will remain standard of care for PBC, PPAR agonists are all very promising, both because of improvement in cholestasis and then mitigation of pruritus. My thought is that this could help a more individualized approach based on patient symptoms, deciding whether we are mainly targeting cholestasis, or in some patients, pruritus. And depending on goals of treatment, we can have a menu of options that we could use.

Dr Flamm: I agree wholeheartedly, and I'm glad you mentioned this combination therapy potential, and we're actually going to get back to that in a few minutes later in the program. Because there are a few other agents we'd like to cover. One of these is tropifexor, which is a novel farnesoid X receptor (FXR) agonist that was evaluated in a phase 2 study. And another is linerixibat, which is an oral small-molecule ileal bile acid transporter called an IBAT inhibitor. Results from a phase 2B study of linerixibat, called GLIMMER, were also published in 2022. Two different drugs with 2 different mechanisms of action. Atoosa, could you briefly describe how agents like these work and then give us top-line data from those clinical studies?

Dr Rabiee: Sure. Let's start with tropifexor, which was a study to basically evaluate safety, efficacy, and pharmacodynamics of this highly potent non-bile acid FXR agonist. This was a double-blind phase 2 study. This was studied as a second-line therapy for PBC patients who had inadequate response to UDCA, and they were randomized to either receive tropifexor at different doses and matched with placebo once daily for 28 days, with follow up on days 56 and 84. Primary endpoint of the study was safety and tolerability, as well as reduction in levels of γ-glutamyl transferase (GGT) and other liver biochemistry. They also had objectives included, such as patient-reported outcomes using a quality-of-life questionnaire. So tropifexor actually did cause a decrease in liver enzymes. The efficacy was confirmed by a dose-dependent significant reduction in the cholestatic marker GGT at week 4. And by day 28, they showed that there was 26% to 72% reduction in GGT.

Alkaline phosphatase did decrease in those with 60-μg to 90-μg doses; however, very few patients achieved normalization of ALP. In the study, 3 patients discontinued treatment because of AEs, which was mainly pruritus. And this was most frequent in the 150-μg dose, although, again, the events were mild to moderate severity. There was a significant decrease in low-density lipoprotein (LDL), high-density lipoprotein (HDL), and total cholesterol during treatment; however, after discontinuation of the drug, this was stabilized.

The second agent that you mentioned in the GLIMMER study -- linerixibat -- the efficacy and safety of this ileal bile acid transport inhibitor was studied in PBC patients who had moderate to severe pruritus. And their primary objective was to assess those related changes in mean worse daily itch score (MWDI). They did show that there were 2 or more points mean reduction in the score at week 16, although this was not significant from placebo in the primary intent-to-treat analysis. In their per-protocol population, there was a significant relation[ship] between total daily dose and response to treatment. The most frequent side effect, as expected from the mechanism of action, was diarrhea. Fifteen patients in this study actually had to discontinue the medication due to side effects, which again, were mainly diarrhea or abdominal pain.

Dr Flamm: Well, thank you so much, Atoosa, and I'd like to quickly mention one last agent of interest, and this is an inhibitor of NOX1/4 called setanaxib. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases -- or the NOXes -- produce reactive oxygen species. And in response to cellular stress, such as injury to cholangiocytes or hepatocytes, the NOX1/4 activates inflammatory and fibrotic pathways. Setanaxib has been shown to inhibit both inflammation and fibrosis in models of advanced cholestatic liver diseases. Interim results from a phase 2 study were published in 2019, and they're shown here. This was a 24-week, placebo-controlled, phase 2 study in patients with PBC and inadequate response to ursodeoxycholic acid. It was 111 patients, so it was a large study divided into 3 groups: 1 placebo; 2 others got different dosages of setanaxib. And an interim analysis at 6 weeks showed a reduction in GGT that was greater for the setanaxib treatment arms than it was for placebo.

And in fact, when you looked at patients that had the highest GGTs and received the highest dose of setanaxib, they had the largest reduction in GGT; so, there was some promise here, as well. Now, I mentioned that I was going to discuss a little bit more about combination therapy. And given the complex pathophysiology of PBC, it's apparent that future regimens will involve some sort of combination therapy, as Atoosa alluded to when she discussed the PPAR agonists. Already, some clinicians are adding fibrates that are available off-label to therapy with ursodeoxycholic acid and/or obeticholic acid in PBC patients who do not achieve an adequate response with the approved agents. Raza, do you in your practice use triple combination therapy off-label, and are there any data to support this approach?

Dr Malik: Thank you, Steve. Interestingly, there's not a huge amount of data out there in triple therapy with ursodeoxycholic acid, obeticholic acid, and fibrates in difficult-to-treat PBC patients. This is being done off-label in individual clinical practices, and my current clinical practice is to give dual therapy, combination therapy, and enter a patient into a clinical trial if appropriate. If we look at patients -- and studies -- who've looked at this triple therapy combination of ursodeoxycholic acid, obeticholic acid, and fibrates, in terms of the literature, we can find an uncontrolled retrospective study of only 58 patients with PBC who failed dual therapy. And the dual therapy could either be ursodeoxycholic acid with obeticholic acid, or ursodeoxycholic acid and a fibrate. And in this group of 58 patients, 29 of the patients received obeticholic acid, a second-line therapy, and fibrates as third-line therapy (the OCA-fibrate group), and 29 patients received fibrates as second-line therapy and obeticholic acid as third-line therapy (the fibrate-OCA group).

The median duration of triple therapy was 11 months in this study. If we compare it to dual therapy in this retrospective analysis, 22% of the patients had an improvement in their alkaline phosphatase at 1 year. The effect was stronger in the obeticholic acid-fibrate group than the fibrate-obeticholic acid group, with an odds ratio of 3.4. There was also a significant decrease in GGT, alanine transaminase (ALT), aspartate transaminase (AST) and total bilirubin [levels], with improved pruritus in the OCA-fibrate group but not in the fibrate-OCA group. No patients discontinued triple therapy during the study, which I find unusual.

Dr Flamm: That certainly is a very provocative study, Raza. I would submit to you, though, that prior to people doing this on a routine basis in practice, we would await additional data on this approach. Well, this certainly has been a great discussion. We've talked about PBC and current therapy and then many of the emerging therapies for PBC that hopefully will be available in the near future. I'd like to wrap up with some concluding remarks. It seems that the prevalence of primary biliary cholangitis is increasing in recent years. Ursodeoxycholic acid as a primary therapy and obeticholic acid as a therapy for people that don't have an optimal response to ursodeoxycholic therapy, or who don't tolerate it, have improved outcomes for many patients. But there are clearly unmet needs, and this is due to the fact that many people do have an inadequate response to these medications. And that may also be limited by some of the adverse effects for both ursodeoxycholic acid and obeticholic acid.

There are new treatments in clinical development, particularly PPAR agonists, and they offer great promise for the treatment of PBC. Combination therapy in the future will likely play an increasing role, and that's not surprising since PBC seems to effect its damage by many different pathways. Treatments that affect these different pathways may be additive, or even more than additive, in ameliorating the disease. So please stay tuned for future developments. Atoosa, Raza, I'd like to thank you so much for joining me today and providing such a stimulating discussion. And I'd like to thank you for participating in this Medscape activity. Please continue on to answer the questions that follow and complete the evaluation.

This transcript has not been copyedited.