Alpha-1 Antitrypsin Deficiency: Are You Overlooking a Leading Genetic Culprit in Liver Disease?

[00:15:02]

Introduction 

Dr Mark Brantley (University of Florida): Welcome, ladies and gentlemen, to today's continuing medical education webinar entitled: Alpha-1 Antitrypsin Deficiency: Are You Overlooking a Leading Genetic Culprit in Liver Disease?

Faculty

My name is Mark Brantley. I'm a Professor Emeritus at the University of Florida. My colleagues joining us are Dr Virginia Clark, a Clinical Professor of Medicine at the University of Florida; Jeff Teckman, a Professor and Vice Chair of Pediatrics at Saint Louis School of Medicine; and Dr Pavel Strnad, Full Professor at the Department of Internal Medicine in Aachen.

Learning Objectives

Our learning objectives today are as listed.

Pretest 1

I'd like to begin with a pretest. How many patients with alpha-1 antitrypsin do you provide care for in a typical month? Okay. Thank you.

So for a pretest, which of the following clinical presentations would be most likely indicate alpha-1 antitrypsin deficiency?

1. A 6-year-old patient presenting with asthma;
2. An 8-year-old patient presenting with cirrhosis;
3. An 8-year-old patient presenting with lung disease; or
4. A 35-year-old patient presenting with hepatocellular carcinoma.

Make your choice. Thank you very much. Looks like the 8-year-old patient presenting with cirrhosis is a very likely choice from that standpoint.

          Pretest 2

Let's move on to the next pretest. A 50-year-old patient presents with newly diagnosed COPD. Which of the following would be the next best step to identify an alpha-1 antitrypsin deficient individual?

1. Alpha-1 antitrypsin serum levels;
2. Genotyping;
3. Liver biopsy; or
4. Liver function test.

Make your choice now. Very good. I think that the most important thing would be to do a serum level of alpha-1 antitrypsin, followed probably by genotyping from that standpoint.

          Pretest 3

Third pretest. A 70-year-old person is diagnosed with alpha-1 antitrypsin deficiency. Which of the following tests would be best to recommend for initial monitoring?

1. Evaluation for liver transplant;
2. Hepatocellular carcinoma screening every 3 months;
3. Liver biopsy to quantify the amount of alpha-1 antitrypsin accumulated; or
4. Liver elastography to measure liver stiffness repeatedly and periodically, based on results.

Make your best choice. Very good. I think that that's probably the appropriate thing, is liver elastography to determine whether the individual has a fibrosis in their liver.

          Pretest 4

Pretest again. What type of investigational therapeutic agents are patisiran and vutrisiran used for?

1. Autophagy enhancement;
2. Chaperone molecules;
3. DNA editing;
4. RNA interference; or
5. RNA editing.

Make your choice. Very good. RNA interference is the correct answer in that particular case.

Now, I'd like to begin our discussions by introducing Dr Jeffrey Teckman. Jeffrey Teckman is a world's expert in alpha-1 antitrypsin deficiency, and he'll be talking about an overview of alpha-1 antitrypsin deficiency. Dr Teckman.

Overview of Alpha-1 Antitrypsin Deficiency

Dr Jeffrey Teckman (Saint Louis School of Medicine): Thank you, Dr Brantley. Welcome, everybody. We're going to start out with a patient perspective to remind us why we're wanting to learn about this disease.

Patient Case

Speaker: I was diagnosed with AATD after transplant. In 2003, I started having problems with high liver enzymes and went through a battery of tests for the next 10 years, and no one ever thought to check for a genetic disorder. Of course, I didn't understand what it was.

In 2012, my mom passed away from a lung disease, her brother, a couple years later, with lung disease. We didn't put the 2 and 2 together, and then I ended up with inoperable liver cancer. With inoperable liver cancer, I was told I needed a liver transplant, and I was devastated. I didn't understand what was going on, because I thought, "I have done everything I'm supposed to do. How could this actually happen?"

After my liver transplant, they came in and they said, you have alpha-1. And I was like, what? And then I had to go find the information out, because I was not educated on what alpha-1 was, how it would affect me or affected my family. In looking back, I can see that if I would have been diagnosed, my mother could have gotten treatment, my uncle could have gotten treatment for their lung issues. And now, just this year, my brother, on May 27th, had to have a liver transplant, because he had AATD.

Dr Teckman: So yeah. Powerful story of this genetic disease working through families.

Background of Alpha-1 Antitrypsin Deficiency

Let's start there and review the background of alpha-1 antitrypsin deficiency. So the SERPINA1 gene is the gene that encodes alpha-1 antitrypsin. It's an autosomal recessive or codominant disease. What was called M allele or MM is 98% of the population. That's the normal wild-type condition.

The Z variant is the most common disease associated allele, although S is also sometimes associated with disease. And we'll talk about that in a minute. ZZ individuals are about 1 in 1500 to 1 in 3000 individuals in the United States and Europe, and about 90% of patients with AATD disease are ZZ.

SZ individuals can develop a ZZ-like disease, but the risk is much lower. But still they do turn up. So in MZ individuals or heterozygous, sometimes people call heterozygous carriers, that's about 2% of the population in North America and Europe. Generally regarded as a modifier of other liver diseases, adding some small risk, again, which we'll talk about in a minute.

This just shows the frequency of the Z gene around the world. There is a founder effect. You'll see the yellow and orange is the highest ZZ frequency in Scandinavia and the Baltic regions, and then the genetic diaspora of those individuals, North America, Australia, New Zealand, and other parts of the world.

Interestingly, the S mutant that we mentioned has a founder effect in Spain and Portugal. So you do see an interaction in Central European gene pools of Z and S and SZ individuals.

So how does AATD work? Well alpha-1 antitrypsin, the protein, is predominantly synthesized in the liver and then secreted into the blood. It's synthesized in the liver in very, very large quantities, second only to albumin as a single protein. The physiologic role of alpha-1 antitrypsin is to protect host tissues during neutrophilic inflammation.

However, the Z gene encodes a mutant protein. The mutant protein accumulates in the liver rather than be secreted. So the serum is deficient in alpha-1 antitrypsin, so it's a serum deficiency, which is how it got its name, but the liver has too much. The liver is a storage disease. The misfolded protein, which cannot be secreted, accumulates in the liver, triggers an intracellular injury cascade and causes fibrosis and hepatocellular carcinoma in some individuals.

This is just a cartoon that shows what we just said. On the left-hand side would be a normal MM wild-type individual. The little wavy lines would be the nascent polypeptide chains of alpha-1 antitrypsin, which then fold up into the green notch, which is the secretion competent conformation of the protein and secreted into the blood. But in the ZZ individual shown on the right, they still make a lot of the alpha-1 antitrypsin polypeptides, but very few are secreted into the blood. Most remain in the liver.

Now, there is a robust protein degradation pathway within the hepatocyte to try to deal with this accumulation of mutant protein, but still some of the protein accumulates, forms these unusual polymers of protein, and causes liver injury.

Photomicrographs

Here are photomicrographs. On the left, an H and E of a ZZ human liver. The features of alpha-1 antitrypsin deficiency in a liver biopsy are typical of many other liver diseases. Inflammation, fat accumulation, fibrosis. Really, on H and E, it's very difficult to distinguish MASH or alcohol from alpha-1 antitrypsin without special stains, as is shown on the right-hand side and in the high magnification.

The red globules or granules shown in some of the hepatocytes are actually the accumulation of the Z protein causing injury. It really illustrates why so many adult ZZ individuals are misdiagnosed as MASH or alcohol liver disease unless specific testing for alpha-1 antitrypsin is done.

On the left hand side is a graph. The vertical axis is serum alpha-1 antitrypsin level. You see there the bar for MM, for normal wild-type individuals, and then the intermediate level with MZ heterozygotes, and then ZZ and SZ, how they're quite low.

And then on the right hand side of the table, again, what we talked about, the prevalence of the disease ZZ, SZ, and MZ individuals and the odds ratio for the risk of cirrhosis. So at least 20 times elevated for ZZ individuals, a small elevation for SZ, and a very mild elevation for MZ, which again is often in the context of another liver disease.

And then the hepatocellular carcinoma risk, which again is significantly elevated for ZZ individuals there at the bottom and mildly increased for SZ individuals.

What about liver disease versus lung disease? So the prevalence in ZZ individuals is quite different. Maybe 50% to 75% of ZZ individuals have some kind of lung disease or lung dysfunction. It's very hard to say about the liver. Cross-sectional studies would suggest 10% to 20% of ZZ individuals with some fibrosis, longitudinal studies, maybe a 20% or maybe as high as 40% lifetime risk of cirrhosis, but maybe it's not that high. Hard to know. Again, the passive physiology of the lung disease is a serum deficiency, but the liver disease is a storage disease.

 Disease Burden

This again shows the disease burden in another way. Here at the top are the odds ratio in ZZ. Here in the top line is fibrosis and cirrhosis, significantly elevated 20 times or more. HCC, again, significantly elevated. Cholelithiasis is only slightly elevated. And then chronic bronchitis or emphysema, again a 10 to 20 to 40 odds ratio increase.

The lower left shows liver stiffness by vibration-controlled elastography, also known as FibroScan. And the orange dots are MM individuals, the green dots, ZZ individuals, a large study again showing you have this tale of a large population of ZZ individuals with significant fibrosis and the summation of the study in the lower right table, showing F2 or greater in 22%, F3 or greater in 12%, F4 in 5% of that particular study.

Clinical Presentations

What about the clinical presentations? Again, highly variable in infants neonatal cholestasis is seen in a minority of ZZ individuals, ZZ newborns, mostly that resolve spontaneously. Very few infants go on to life-threatening disease, but some do. Some children present with hepatitis or cirrhosis, although that's not very common.

Mainly we see, in older adults, the development of COPD, bronchiectasis, hepatitis, cirrhosis, and HCC. Genetic and environmental modifiers appear to play a very large role. Smoking plays a huge role in the risk of lung disease and alpha-1, but probably doesn't have impact on the liver.

Obesity metabolic syndrome, however, appear to be major modifiers of the liver disease. Neonatal cholestasis is a modest risk for liver disease going on to cirrhosis, and we don't see a strong link to alcohol, though still being studied.

Outcomes

What about outcomes? At the moment, there's no specific treatment other than general liver supportive care and liver transplantation. Liver transplant has had excellent survival rates. We also, however, advise all people with alpha-1 and all people to avoid smoking.

Liver transplant or death, again, in children is very low, maybe 3% or less, higher in adults. And again, the risk of HCC is increased.

So if you look at some of the studies, looking at cause of mortality, it seems in many studies to break down by never smokers versus sometime or ex-smokers. On the left is never smokers. and this is cause of death. And the red is liver disease. The blue is emphysema. But if you look in smokers, then you see the majority cause of death is related to lung disease and only a small amount liver disease.

This has been the beginning in our overview. We have a question that can pop up for this section.

          Pretest 1

Which of the following clinical presentations would most likely indicate alpha-1 antitrypsin deficiency? We talked about this earlier.

1. A 6-year-old with asthma;
2. An 8-year-old with cirrhosis;
3. An 8-year-old with lung disease; or
4. A 35-year-old with HCC.

Everyone did very well on this earlier.

Right. The one thing we didn't touch on is lung disease really doesn't develop in children. Children may have asthma, but lung disease takes decades to develop and generally seen in adults.

So now I'll introduce you to Dr Virginia Clark, who's going to continue to talk about the liver. Dr Clark.

Practical Guidance for how to Diagnose Alpha-1 Liver Disease and Assess Individuals for Liver Disease

Dr Virginia Clark (University of Florida): Thank you very much, Jeff. I always learn something from your talk. So my section to talk today about is a practical guidance for how to diagnose alpha-1 liver disease and assess individuals for liver disease.

Patient Case

I'm not starting with a video, but I will start with a patient case challenge, very practical, what you might expect to see in a clinical practice, which is a 50-year-old woman presenting to the hepatologist who has complained of dyspnea, but she also has a diagnosis of MASLD. She has a 8-year history of elevated liver enzymes and with multiple liver ultrasounds showing fatty liver.

She has the typical risk factors for MASLD, which is hypertension, diabetes. She also has a history of asthma. She's taking medicines for her hypertension and diabetes. But her family history is notable for her mother and a maternal uncle who passed away from lung disease, but no family history of liver disease. Her liver enzymes and laboratory values show that a modestly elevated ALT and AST, total bilirubin is normal, and the test to evaluate for other causes of liver disease were negative. Hep C and hep B surface antigen were negative.

          Poll

Our next polling question would be, which of the following recommendations is the best option for this patient at this time?

1. Order ALT serum levels;
2. Order alpha-1 phenotyping or genotyping;
3. Order of a follow-up biopsy; or
4. Refer to pulmonology for further testing.

That's right. Starting with the serum level is a great place to start, and you can see that there's a distribution of answers. Some wanted to go straight for a biopsy.

Well, I think the reason I want to emphasize in this conversation about alpha-1 is that alpha-1 actually remains underdiagnosed and underrecognized in the general population.

We know this, I think one of the nicest studies that looked at this was a large population from the UK Biobank, where individuals were tested when genetic material was available. And it's a large, large sample size. And it could be told if they were, genetically, if they had alpha-1 or not, if they were ZZ, and of those who were found to be ZZ, only 6% of them had a concurrent diagnosis of alpha-1. So it shows us that we're not doing a great job in diagnosing these individuals.

Other sources of data. Also look at this question in 2 different ways. Whether or not individuals who are impacted with lung disease are tested. It suggests that only 2% of patients with COPD have ever been tested for alpha-1, which is a big gap in care.

And then when you ask individuals who have been diagnosed with alpha-1 who have lung disease and get some idea about how long it takes for them to develop symptoms from their lung disease, it's usually, a 5- to 8-year on average time from first onset of symptoms to when they're eventually diagnosed with alpha-1. And we heard that in our patient story in the first section.

From liver disease, the data is not quite as robust, but we have seen this from those who are impacted with more advanced disease. This was a study from a large transplant center in the US. And they looked at everyone, the explanted transplanted liver, and when they found the PAS positive globules or the alpha-1 like Dr Teckman showed you in the biopsy slide, only a third of them had a known diagnosis of alpha-1 prior to their transplant.

And these are, presumably, individuals who have been evaluated completely for all causes of liver disease. And so 39% of them, the diagnosis of alpha-1 was made after the transplant, and even more concerning is that the practitioners who are the people who are caring for patients, who saw the biopsy, who had alpha-1 on the biopsy, they never followed up with confirmatory genotype testing. So that's another missed opportunity and one of the reasons why alpha-1 still remains under-recognized.

Diagnosis

So how do we make the diagnosis? It's not a difficult diagnosis to make. The hardest thing to do is think about it. I think all the guidelines, most of the guidelines suggest that you start with the serum AAT level, depending on where your practice is and what you have access to. But you have to be sure to interpret the alpha-1 level with some caution. If the patient is infected at the time or have some other degree of inflammation, it can be falsely elevated as an acute phase reactant.

And if you're testing someone post transplant, or if you have had somebody who has alpha-1 who is on infusions, then you're going to get a result that reflects the fact that they're on infusions or the liver donor.

So the gold standard really is genotyping and phenotyping. If genotyping is not available, you do not need a liver biopsy to make or even to confirm the diagnosis. Genotyping has come a long way, and so it's much easier now to just do a simple cheek swab or a finger stick to get a small amount of blood for DNA to be able to efficiently detect the mutant alleles.

And then phenotyping is an electrophoresis technique and it evaluates the serum protein type. So it can tell you MM, MZ, ZZ, or SZ, and then the genotype can be inferred. Sometimes there can be some problems with this particular testing, and it's limited to the more common alleles, the Z and the S, so it's not always completely if you have a very rare genotype acronym.

Why is it important to make this early diagnosis? I've told you it's underdiagnosed and that the diagnosis is easy, and it's because the mortality data that we think we can impact that from what Dr Teckman showed you. There are improved survival and clinical outcomes, especially in never smokers if you can intervene early.

And the way that we can intervene on the liver side, we are not there yet, but for individuals who are impacted with lung disease, augmentation therapy can be started. And while it doesn't reverse what's already been lost from emphysema, it can prevent additional loss of lung tissue, and that translates into less symptoms and improved quality of life.

The other reason I think that we should think about the importance of early diagnosis is because there's an increased incidence of liver cancer in individuals with a PiZZ genotype, that we know about and that we probably should think about screening patients for.

Then if you know you have alpha-1, if you identify a family group, then you can encourage smoking cessation or avoidance, and even things like if you identify early occupational counseling, people who are exposed to fumes or toxins in their job, either if they can't change that, which sometimes may be hard, but they could make sure they take appropriate precautions to protect their lungs. Even though there's no great data on alcohol, I think it's still probably a wise counsel to avoid alcohol especially if you have concurrent fatty liver and to maintain a healthy weight. These are all interventions that we can suggest.

Study: Cancer Question

This is a study that was published in the fairly recently looking at to show you a little bit about the cancer question. Although we know that the increase risk of liver cancer is higher in individuals who have cirrhosis, this was an interesting longitudinal study based out of Sweden. From there, a population of disease that had been followed over many, many years, and then using match controls population, everything was controlled for all the risk of cancer, smoking, gender, age.

What was seen over time was that increased incidence of any type of cancer was found in individuals with ZZ, and specifically also nonhepatic cancers as well as hepatic cancer. So if you can make an early diagnosis, there may be a potential for improving cancer screening or just awareness that that cancer risk exist.

So why is it that early detection of alpha-1 is not so good? It really goes back to what Dr Teckman said initially, is because we know that liver disease is prevalent, but it may vary in different populations, and we also know that with different disease modifiers, that the risk may not be the same. So it's a heterogeneous disease both in clinical presentation and how it manifests.

In a large group of individuals from the DNA tissue data bank were tested, what I show you there is the data that liver enzymes are at a cross-sectional. You can see anywhere from across all age groups, maybe 8% to 10% of individuals who were known to have liver disease had an abnormal ALT. And some who were known to have liver disease, their ALT was normal. So it does not necessarily correlate. I think that it overlaps with metabolic liver disease, and so people don't think about alpha-1. They see MASLD and they stop and they don't scratch any deeper. And I think those who are diagnosed with lung disease may be not always effectively or screened for liver disease.

So what's really recommended is not testing for alpha-1 at a population level, but really testing kind of more targeted, and that's because it is a rare condition, and so you want to identify populations who are at risk for alpha-1. And those populations are pretty clear. That's adults with COPD, adults with symptomatic emphysema, adults with asthma and incompletely reversible airway obstruction after bronchodilator therapy that suggests some component of COPD, and then, of course, all immediate family members of individuals with alpha-1 because if you can find an alpha you can generally find an alpha family. And then patients with unexplained chronic liver disease and patients who have undergone an initial evaluation of MASLD. I think they deserve a further look for alpha-1, because the testing is pretty straightforward and easy.

What the guidelines will say is to measure the alpha-1 level and the CRP level and the serum. Although in practice the CRP levels are not routinely measured, it's just a starting point. It's an alpha-1 serum level, and then to confirm that with genotyping.

You've seen this figure before, but the reason we want to evaluate is to see what is the clinical prevalence of liver fibrosis. So in a very large cross-section of individuals who are PiZZ, this is from multiple centers in Europe, you can see that liver stiffness range. In unselected patients, you can see that liver stiffness was quite high. And that we know that liver fibrosis will progress in over a third of patients based on a repeat liver biopsy study. And so that's why we advise ongoing monitoring for liver disease and in individuals who have the PiZZ genotype. It may progress.

So what is the right cut off? This is a question we might not know the exact answer to, but we're trying to get to the heart of it. There's some variability in the studies about what is the appropriate cutoff to look for maybe F2 fibrosis or more advanced fibrosis. And so in a recent meta-analysis, looking at the available data, suggested that if there were significant fibrosis, if the liver stiffness measurement was greater than 7.1 KPA, and that advanced fibrosis was likely if the liver stiffness measurement was greater than 9.5 KPA.

There's very limited MRE data and so any fibrosis, they just looked at the cutoff of greater than 3 KPA for an MRA. So that's not as common. It's not a most effective screening tool, which is what we would like to do for point-of-care testing for individuals with alpha-1.

 Role of Liver Biopsy

What is the role of a liver biopsy? I would say it's quite limited. I think where I use it and where a lot of people use it is when if you're noninvasive, testing is inconclusive or discordant, you want to just high fibrosis, one low fibrosis, or if you're really concerned that there might be an additional second hit.

We know, from a lot of other studies, that there is 10% to 15% of patients may have more than 1 liver disease. There could be something else. So you might want to, if you're concerned, you could do a biopsy to rule out autoimmune or more advanced MASH or things like that.

So I can show you this is a pared down version of what is a suggested approach to monitoring for alpha-1, and this certainly needs to be validated, but this is what was suggested after getting a group of experts together looking at the data.

So the starting point would be to start with a liver stiffness measurement evaluated by transient elastography, and then depending on the cutoff, you can see where you might think about reevaluating. So this cutoff would be less than 8 kilopascals. And then probably every 2 to 3 years knowing that fibrosis progression is slow. But if you're in this indeterminate or intermediate range of a kilopascal on your transient elastography anywhere from 8 to 13, this is where you might consider additional noninvasive measures, such as an MRE or an ELF testing or even depending on what's available in your location or liver biopsy, if you have discordant results from greater than 2 noninvasive testings.

And so then how often if you establish that the F2 fibrosis or F3 fibrosis is present, it's probably pertinent to reevaluate them every 1 or 2 years, that is because the rate of fibrosis progression in individuals with alpha-1 is not super well established, and there is definitely some variability depending on what the other genetic modifiers are underlying risk factors for disease might be.

And then finally, if you end up with a transient elastography score of 13 or greater, or if there's clear evidence of advanced histology or advanced liver disease at the time of the diagnosis of alpha-1, which is often the case, then it's usually routine standard of care that you would do for any individual with advanced chronic liver disease following the MELD score, or even referring for liver transplant and using your clinical judgment, really for how frequent to monitor individuals based on their disease presentation.

Okay. All right. Our follow-up testing then is a 50-year-old patient presents with newly diagnosed COPD. Which of the following would be the next best step to identify alpha-1? Yes. I think a level is where you start, but the best step to completely identify would be the genotyping test.

          Posttest 2

Okay. A 50-year-old patient presents with newly diagnosed COPD without that, serum level genotyping and liver function test. And the rationale is that that's where you start. It's considered the gold standard. And so you just need to know how to make and confirm the diagnosis.

          Posttest 3

Third question. A 70-year-old patient is diagnosed with alpha-1. Which of the following would be the best to recommend for initial monitoring?

1. Evaluation for liver transplant;
2. HCC screening every 3 months;
3. Liver biopsy to quantify the amount of alpha-1 accumulation; and
4. Liver elastography to measure liver stiffness, repeated periodically based on the results.

Yes. The liver elastography to measure liver stiffness, repeated periodically based on results, is the most efficient way and noninvasive way, probably the most cost efficient to help evaluate these patients, just for routine monitoring.

Any signs of advanced fibrosis, then is when you start to go into screening for hepatocellular carcinoma, but it's usually every 6 months instead of every 3. Depending, they'd have to have more advanced symptoms to be considered for liver transplant.

With that, I'd like to turn over the rest of the program to Pavel Strnad, our colleague from Germany, who's going to talk about current management strategies for alpha-1.

Current Management Strategies for Alpha-1

Dr Pavel Strnad (University Hospital Aachen): Thanks a lot, Ginger. Thanks a lot, Jeff. So it's basically my task now to bring it home and to take advantage of all the great stuff which was already presented, and to show you actually what can be done when you meet these patients in the clinical routine and that now we have emerging treatment possibilities, which makes it even more important to really screen for this condition.

Patient Case

We will start with our case challenge. This is a patient where after seeing a hepatologist, additional tests were ordered. And as you can see here, there is this strongly decreased AAT serum level 0.2. The normal range starts at 0.9. And this very low alpha-1 antitrypsin serum level the really predominant cause of the ZZ genotype, which was the case here. So if you know all these things, what are your next considerations for this patient?

I think it was laid out very beautifully by both Ginger and Jeff that given that this is an inherited disease, the ideal way to approach it is to get some kind of noninvasive liver fibrosis testing, because you cannot poke the liver all the time, otherwise the patients will run away. And this was done here, and we see NVCT[?] just above 10 kilopascal, and we see APRI above 1, which is also quite elevated.

The question is, what are these values really telling us? And we know the data from more prevalent diseases, but up to recently, we didn't have that much data on alpha-1 antitrypsin deficiency. This changed luckily. Now there is a large longitudinal follow-up study which had nearly 750 of these patients, all of them received at the baseline a noninvasive liver fibrosis testing and had a median follow-up of 3.5 years, and 37 of them passed away.

You can see that the liver-related death was even more prevalent than the lung-related death. So this shows you that the mortality in AATD depends also a little bit on who looks. So if this is a more hepatologist-driven cohort, then obviously you have more liver-related deaths, and the same thing, the liver-related events here were a little bit more numerous than lung-related events. And for the liver-related events, we counted the usual ones, the compensated liver cirrhosis, need for liver transplant, liver-related death, HCC.

If you do all that, you see that basically the classic noninvasive fibrosis tests that we use in the clinical routine are performed quite nicely. VCTE is what we call here liver stiffness measurement, APRI we have had before, and you can see in our particular patient, we have a VCTE of over 10, which gives us a risk in this orange area, and the APRI was above 1, which is even in the red area, so relatively advanced fibrosis probably something like F3 with significantly elevated liver risks. And you can see that both of these noninvasive liver fibrosis tests are great predictors with area under the curve over 0.9, which is meta-analysis seen for in the clinical routine.

So what is even probably more important because as we said alpha-1 antitrypsin deficiency is a disease primarily affecting both lung and the liver is that you can do a similar triage testing for lung disease, and for this you can use the normal PFT, especially the FEV1 percentage. And obviously the lower the FEV1 percentage, the higher the lung-related risk. And based on FEV1 and VCTE or APRI, you can try to estimate the relative risks and say whether this might be a patient with a leading lung or liver disease.

These data are really something which shows that the delphinol[?] that Ginger previously explained really makes sense. So based on VCTE, you can do some kind of triage into the green low-risk patient population that you may need to see only every 2 to 3 years. The yellow population where maybe only 1 to 2 years might be reasonable or where even additional liver fibrosis tests might be helpful to see whether this is going more towards the red area or still being greenish, and then you have the red area where you really have to take care of them and consider an islet transplant, because patients with alpha-1 antitrypsin deficiency can decompensate quite quickly. And given that liver transplant has a very good outcome in these patients, you may want to consider discussing liver transplant early on with them.

The somewhat frustrating part up to recently was basically when you identify the patients, what you can do with them. Up to now, we have no approved liver-related drug. So we can basically recommend them general lifestyle modifications, obviously, no smoking to protect their lung, and avoidance of alcohol, and trying to stay lean to stop or to prevent liver fibrosis development.

On the lung, we have reasonable action items. You can treat the lung similar as COPD, and you can give them weekly injections of alpha-1 antitrypsin, which is called augmentation therapy. And for lung, it's very important to do regular vaccination to prevent from unnecessary lung infections. But as I said, for the liver, up to now, we didn't have too much, but we will play a patient case to really see how it feels in a real life and how challenging this is.

Patient Case

Speaker: So upcoming advancements in AATD treatment is really imperative for patients, because just having 1 option, which is a liver transplant, is overwhelming. And for a patient to have multiple options to say, "Well, I can take this medication or I can do this and possibly not lead to liver transplant," I think that that's going to be really valuable for patients in their mental health, their families, to really understand and say, "Okay, I do have options," because it's really hard to process when the only option you have is to go get a liver transplant and not to be able to take any kind of medication that will help ease symptoms or help actually possibly not even have to go to transplant.

Dr Strnad: I think this is a very clear and powerful study, and that's why we have to get better on the treatment for AATD. And as Jeff explained earlier on this is basically a disease caused by accumulation of this misfolded toxic protein, and this has been known for a long time, and there have been different treatments that were studied to actually get rid of this toxic protein.

You can try to degrade them by autophagy enhancers such as carbamazepine or rapamycin. You can try to improve their folding by chaperone-like molecules, like mannosidase 1 and 2 inhibitors or glucosidase inhibitors, also for PBA or SAHA are very known well known chemical chaperones.

But all these things actually work nicely in experimental models in cell cultures. But some up to now were not proven to be efficient in humans. The same issue with is monoclonal antibodies that again try to block the misfolding and the formation of large toxic polymers. Because of this gain of function toxicity, there have been also several gene therapeutic approaches that have worked in experimental studies. But some, so far, need to be translated into a clinical routine.

The Clinical Trial Landscape for AATD Associated Liver Disease

And this brings us to the clinical trial landscape for AATD-associated liver disease. As you can see, we can try to interfere on all 3 levels of protein production, either on DNA levels with either CRISPR-Cas or DNA-based editing. On RNA level, we can do the same. We can either silence the production of the protein or we can actually modify it with RNA editing. And then on the protein level, we can somehow try to improve the secretion and the 3-dimensional structure of this RNA formed protein.

So out of these approaches, the one which is clinically most advanced is the siRNA approach. Again, this comes from the idea that the PiZZ is toxic, and first to produce the protein, you need to produce an RNA, which is a short living copy of our genetic information, that is then used to produce the protein itself. And you can interfere on this RNA level to stop the production. The interference on RNA level has the big advantage that you don't mess up with the genes which may have all the potential gain of function, mutation, consequences, and so on. So you act on a short living molecule rather than on our gene biobank, basically.

One of these compounds is called[inaudible]. These are the phase II data. You can see that if you use this compound, you can very quickly reduce the production of the alpha-1 antitrypsin. And you have here both the data from the serum levels and data from the liver biopsies. In both cases, it was possible to decrease the AAT levels by about 85%.

That is another phase II study which just got published a few months ago, which was a placebo controlled, randomized clinical trial. And you can see that this siRNA is actually very well tolerated. The big advantage of this siRNA approach is that this is targeted directly to a hepatocyte through a special glycosylation so that it doesn't get into other tissues. And because of that, we see likely this good toxicity profile.

You can see here the same thing. We don't have any increase in treatment-related adverse events. We have very few CNS treatment-related adverse events and similar numbers in placebo group and the high dose [inaudible], and we had no treatment associated adverse events that would lead to study interruptions and no tests.

This brings us back to one of our question, and we will see how you improved during the course of my talk. So which type of investigational therapies do vutrisiran and patisiran use? So let's see. So as more than 80% of you actually correctly stated it's an RNA interference or siRNA treatment for both of these compounds. So looks like you did listen a little bit.

And that brings me to the end of my job, and I will hand over to Mark Brantley to lead the faculty panel discussion.

Q&A

Dr Brantley: Thank you, Dr Strnad. This has been really some excellent talks that I hope that you've stirred some questions in your mind regarding this. Laura had a specific question that was, will elevated liver enzyme diagnosis with negative hepatology panel and the such negative for alcohol be enough to get insurance to pay for testing for alpha-1 antitrypsin deficiency? I'm going to leave that to Dr Clark to answer.

Dr Clark: I think that should be sufficient, because if you've done all the diagnostic testing for abnormal LFTs and you don't have an answer, this is a final piece of that puzzle, and I don't often get a kickback or pushback on the testing for alpha-1.

Dr Brantley: So let me just start with a couple of questions. Are heterozygous patients prone to more severe lung and liver disease than another predisposing condition? Jeff, would you handle that one?

Dr Teckman: Sure. I think that's an interesting question that a lot of people have been looking into for many decades. So there's some fairly good research just in the last ten years or so, that heterozygous MZ individuals who smoke are slightly more at risk for lung injury than MM individuals who smoke. On the other hand, the data seems to suggest that MZ individuals who do not smoke are not at increased risk for emphysema.

With regard to the liver, it's very interesting. We've known, for decades, that as we said, about 2% of the population in Europe, in the United States is MZ. Now, if you go to your liver clinic and you genotype for alpha-1, everyone who's cirrhotic, you would expect to get 2%, but in fact, it's 10%. So that's been repeated in Italy, and in Austria, and the Mayo Clinic, in Cincinnati. So we know that there's this overrepresentation of MZ individuals with severe liver disease.

Now, in some of those studies, those people have more fatty liver disease or they have more hepatitis C. There do appear to be MZ individuals who don't have other risk factors. So there is certainly a small risk of liver disease in MZ individuals, but to any individual person, the risk is very small. As a large group, we can detect it. But in general, we don't think of MZ as a liver disease on its own. But in the presence of other liver diseases, it's probably a negative modifier.

Dr Brantley: We have another question. Jodi[?]. Is testing for alpha-1 a once and done test. Pavel, would you take that one for us?

Dr Strnad: Well, it depends whether you do it right, right? Well, it's as always in life back and forth. So if you have a serum alpha-1 antitrypsin level and you do a genetic test, which explains the serum alpha-1 antitrypsin level, it's one and done because your genes don't change, unless you get transplant. If you get transplant, you may want to test your liver again because you have a new one. But if you do it right and it's one and done, but at the same time, and that's why it's actually this combination of serum AAT levels and the genetic testing.

If you, for some reason do, let's say, own a basic genetic testing like bunch of variants, and these turn out negative, and you have, for example, strongly decreased serum AAT levels, then you have to do a more extensive genetic testing. You may need to do sequencing and so on. So basically your genes don't change. So if you do it right, you need only once. If you don't, you need to repeat it, or you do need to do a more extensive testing.

Dr Brantley: Thank you very much, Dr Strnad. I think that sums up all that. Are there any specific recommendations or considerations for individuals that are MZ? And I will go back to Jeff for that one.

Dr Teckman: Yeah. So the answer is no. For individual people who are MZ, there's no additional recommended screening or anything other than the typical good health advice you'd give an individual. I think the only difference would be to make them aware that they're a carrier. And I guess the context then would be what else is going on in the family. So if there was a family history of lung or liver disease and you tested the individual and they're MZ, then perhaps that suggests that other family members should be made aware and given the opportunity for genetic counseling or testing.

Dr Brantley: I absolutely agree with that. It's a genetic disease, so you have to look in the family. Just like they say, insanity is hereditary. You get it from your children. How about 1 more question before we close up? How often should FibroScan be done on MZ patients and also those with NAFLD or MASLD? Ginger?

Dr Clark: Sure. I'll take that one. I think to add on to what Jeff is saying, if I think about it in reverse, if I am evaluating somebody who has MASLD and I find that they are an MZ, I put that person in a higher risk category in terms of progression of liver disease, because we know that that's been shown in a fatty liver population, more advanced fibrosis can be present, but it's not looking right at the MZ population itself. But I don't change what I do in terms of the monitoring what the guidelines say for MASLD if an MZ is present. I just make the person who has tested aware that it might increase their risk even if they change their lifestyle.

So for MZs, I just get a baseline. If they don't have abnormal LFTs, if they don't have any other risk, I don't put them under a routine screening program just because I feel like. Like Jeff said, it's such a low risk of them developing liver disease in the long run. You're just probably creating too much anxiety around the testing and not really have a lot of bang for your buck.

Dr Brantley: So we might have 1 last question that I'd like to pose to our experts, and that is, should patients that have this ZZ allele be screened for HCC if they don't have cirrhosis? I presume by either biopsy or by FibroScan. Dr Strnad, would you make a comment on that? And I think that I'd like to hear about what Dr Clark and Dr Teckman also think.

Dr Strnad: Well, the problem is always what you do when you don't have that much data. So we know that the large biobank data set say that they have about 40 times increased risk of HCC. We do believe that this is mainly in an advanced fibrosis, so I would definitely screen F3, F4. I would probably offer still once a year ultrasound to lower fibrosis stages patients, because just of abundance of caution. And you would say, "Well, I cannot really say how high your risk is. So I am offering this to you, but we don't think that a ZZ patient with a low fibrosis stage has a huge risk of HCC."

Dr Brantley: Any other comments, guys? I think we're coming to the end of our discussion. I'd like to thank both the faculty presenting and also all the people that attended this. We hope that you have learned lots about alpha-1 antitrypsin deficiency and found a good reason to continue your studies, and always looking for genetic diseases, as they oftentimes are things that we don't necessarily consider in liver diseases.

Thank you very much, ladies and gentlemen.

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