Paraneoplastic neurologic syndromes can present with manifestations at any level of the neuraxis. In patients with high clinical suspicion of a paraneoplastic neurologic syndrome, cancer screening and treatment should be undertaken, regardless of the presence of a neural antibody.

In this episode, Katie Grouse, MD, FAAN, speaks with Anastasia Zekeridou, MD, PhD, author of the article "Paraneoplastic Neurologic Disorders," in the Continuum August 2024 Autoimmune Neurology issue.

Dr. Grouse is a Continuum® Audio interviewer and a clinical assistant professor at the University of California San Francisco in San Francisco, California.

Dr. Zekeridou a senior associate consultant in the departments of neurology, laboratory medicine, and pathology, and for the Center for Multiple Sclerosis and Autoimmune Neurology at Mayo Clinic in Rochester, Minnesota.

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Guest: @ANASTASIA_ZEK

Transcript

Full transcript available here

Dr Jones: This is Dr Lyell Jones, Editor-in-Chief of Continuum, the premier topic-based neurology clinical review and CME journal from the American Academy of Neurology. Thank you for joining us on Continuum Audio, which features conversations with Continuum's guest editors and authors who are the leading experts in their fields. Subscribers to the Continuum journal can read the full article or listen to verbatim recordings of the article and have access to exclusive interviews not featured on the podcast. Please visit the link in the episode notes for more information on the article, subscribing to the journal, and how to get CME.

Dr Grouse: This is Dr Katie Grouse. Today, I'm interviewing Dr Anastasia Zekeridou about her article on classical paraneoplastic neurologic disorders, which is part of the August 2024 Continuum issue on autoimmune neurology. Welcome to the podcast, and please introduce yourself to our audience.

Dr Zekeridou: Hi. Thank you, Dr Grouse. I'm always excited to talk about paraneoplastic neurological diseases. So, I'm an autoimmune neurologist at Mayo Clinic in Rochester, and I spend my time between the lab and seeing patients in the autoimmune neurology clinic.

Dr Grouse: Thank you so much for joining us, and we're really excited to talk about this really important topic. So, to start, I'd like to ask what, in your opinion, is the key message from this article.

Dr Zekeridou: That's a good question - there are a lot of messages, but maybe if I can distill it down. For me, one of the first things is that paraneoplastic neurological diseases can actually affect any level of the neuraxis. It can manifest with different types of presentations. If we do suspect a paraneoplastic neurological syndrome, then we need to look for the cancer, and then if we're not certain, even do an immunotherapy trial. A negative antibody does not make for an absence of a paraneoplastic neurological disease (because, often, we depend a lot on them), but you can see patients with paraneoplastic disease that do not have neural antibodies. And then, we always need to be thinking that if we have a paraneoplastic neurological disease, we actually need to be thinking of both the cancer and the immune response together - so, we need to be treating the cancer, we need to be treating the immune response – because, essentially, paraneoplastic neurological syndrome is evidence of this antitumor immune response. So, the main (if I can distill this down in one) is probably that we need to be discussing all of these patients with the treating oncologist, because they have complicated care.

Dr Grouse: Great. Thank you so much for that summary. It's very helpful. While many of our listeners are likely familiar with paraneoplastic disorders in their workup (which you've mentioned just now), the concept of neurologic autoimmunity in the context of immune checkpoint inhibitor therapy has more recently become widely recognized. Can you summarize this briefly for our listeners who may be less familiar with this?

Dr Zekeridou: I think that we learn more and more about this and we see more and more patients with immune checkpoint inhibitor-related neurological immunity, so, I always think about it in a very straightforward way. So, I think the way we think about immune responses is a balance between tolerance and regulation and immune activations. And then, immune checkpoints are the molecules that help us maintain self-tolerance. So, our immune system - it's probably the best tool that we have to fight against cancer. So, essentially, when we inhibit the immune checkpoints, we actually use our own immune system to fight cancer, but taking the breaks of the immune system essentially can lead to a lot of complications that are immune-mediated. Some of them are neurological - the neurological complications are rare, especially the ones that we need to do something about (so, it's 1% to 4%, in some cases up to 14%), and they do increase when you use multiple immune checkpoint inhibitors together. The main thing for me with the neurological complications is that, sometimes, they are difficult to recognize, they can (again) affect every level of the neuraxis - like, it can be the neuromuscular or the central nervous system (even though neuromuscular complications are much more common than central nervous system complications) - and then a lot of them (the vast majority) will happen within the first three months, but they can also happen even after you stop the immune checkpoint inhibitor. But this three-month interval, it's sometimes useful when you're in a diagnostic silence - it kind of helps you make the decision more towards an immune-related adverse event affecting the nervous system. And then, I think that, practically, once we have diagnosed this patients, we still are not very certain how to treat. All of them will get steroids upfront, but some of them will be difficult to treat, so then, we have to decide on the next treatment depending on evolution. And then, I will just say that (I mentioned it previously, but) these are the patients that the coordination with other subspecialties is one of the main things that we need to do (eg, oncologists) - they often have immune-related adverse events from other systems, so, there is a lot of coordination of care. And, always, the question at the end comes up, Should we be putting these patients back to their immune checkpoint inhibitor cancer immunotherapy that might help them with the cancer? And I think that this is difficult sometimes, and it needs to be decided - most cases - in a case-by-case basis, even though there are some recommendations that I've been discussing in the Continuum article.

Dr Grose: That's great, and I encourage everyone to read more about this, because it is a very complex and fascinating topic. On the note of the immune checkpoint inhibitor neurologic dysfunction - I would imagine these are pretty rare - how common are these? And I would suspect they're getting missed a lot - is that correct?

Dr Zekeridou: I think it's a very good question. Essentially, what we say for the neurological immune-related adverse events (the ones that we need intervention) - so, they are at least of grade two. (I think that there are less than 4%, mostly, probably close to 1.5%.) There was a study where they used double immune checkpoint inhibitors (so CTLA-4 and PD-1, PD-L1) - they were up to 14%, but this was any grade (so, a little bit of tingling, a little bit of headache), while the ones that we actually need to act upon and we need to actually do something about, they are probably closer to 1.5%. So, are they being missed? I am certain that some of them never make it to the neurologist. So, the ones that we know that we are underestimating is definitely the meningitis - because I think it's more common – but, often, when the patients present, they have something else as well. So, the oncologists will put them on steroids and then they will get better - so, we don't really see them in the neurology clinic (the ones with the very mild side effects). And then, also, these patients are often very sick, and they have a lot of things going for them, so they sometimes do not make it to the diagnosis.

Dr Grouse: So then, I want to just take a step back and ask you, what's the most challenging aspect of paraneoplastic neurologic disorders in your opinion?

Dr Zekeridou: I think, for me, one of the main things, the classic paraneoplastic disorders - and when I say "classic paraneoplastic disorders", they are the ones that we think more of with antibodies that are mostly biomarkers of the immune response, and they suggest a cytotoxic T-cell mediated disorder (so, like PCA1 [or anti-Yo] or ANNA-1 [or anti-Hu]) - these patients are very sick often, and we don't have a lot of good treatments for them. And then, even if we treat them, we actually sometimes do not manage to reverse their course - the best that we can do is stabilize. So, I think that this is part of the discussion that we have upfront with these patients - but it is quite challenging, because most of them, we will be giving them a cancer diagnosis ourselves, because we recognize the paraneoplastic neurological syndrome, and we look for the cancer, and then we'll be giving them a cancer diagnosis. And even if we treat their cancer and we treat the immune system, sometimes, then, we don't make a real improvement – like, we stabilize their disease and we sometimes get improvement, but there are cases that we do not and they continue to progress – so, that has been the most challenging aspect of this, and I think that's kind of where we really need more things coming – like, we need more treatments, we need to better understand these diseases and get more straightforward.

Dr Grouse: I agree. I think that's absolutely, uh, what we all hope for these types of disorders, and I can imagine we all can remember at least one case just like this where someone had this type of problem and just didn't respond to treatment. So, strong hopes that there will be improvement with this in the years coming. Another question I have for you is, what in your article do you think would come as the biggest surprise to our listeners?

Dr Zekeridou: I think that, because we discussed that immune checkpoint inhibitors (maybe we don't know as well), so one of the main things for me is when we first started thinking of neurological complications of immune checkpoint inhibitors, there was a lot of myasthenia gravis mentioned (patients presenting with myasthenia gravis), and then some of them antibody-positive, some of them antibody-negative. Now, with the time that has passed by, we recognize that myasthenia gravis is very rare. Like, I've seen tons of patients (probably more than that, actually) – and then, maybe I've seen one patient with de novo myasthenia gravis. We realize that the immune checkpoint inhibitor myasthenia gravis that we were thinking of are – they're mostly the immune checkpoint inhibitor myocytes cases - so, then, this is one of these myopathies that looks like no other. So, it really has a very predominant oculobulbar involvement (that's why everybody was thinking that this is myasthenia gravis), but, practically, the EMGs are negative, the patients do not respond to pyridostigmine - so, practically, these are really myopathy cases. And why is that important? Because 30% to 40% of these cases might also have a cardiomyopathy, for example, and then we're putting all these patients on pyridostigmine and medications that they do not necessarily need. So, I think one of the chains in concepts that we have in the later years is that, really (and this is one of the most common immune-related adverse events that we see in our clinic), that these patients with ICI myositis really present with the oculobulbar involvement and proximal involvement that we can see in myasthenia, but they do not have a neuromuscular junction problem.

Dr Grouse: Now, we've all struggled with identifying a primary malignancy in patients where a paraneoplastic syndrome was strongly suspected. Do you have any tips on how to make this workup as high yield as possible?

Dr Zekeridou: Yeah, I think that's a difficult question. I think it depends a little bit on your patient as well. So, if you have an antibody that makes things easier (and we can discuss about that, but), practically, for me, a patient that I have a high suspicion, that we get a CT chest, abdomen, and pelvis upfront - and often, we don't get PET scans, right, directly, because we have insurance companies maybe playing a role in what we would do. So, I would get this for a woman - she has to have a mammogram. For a man, they have to have a testicular ultrasound. That's the basics for me. And then, when we see more younger women or when we suspect an MDA, then they will need to have the ultrasound to look for the ovarian teratomas or an MRI of the abdomen - so, the PET scan for me, if I have a high suspicion, it will always be the next step. Like, we have increased diagnostic yield with PET scans, but we also need to remember, what are the tumors that you will not find on a PET scan? Teratomas are not PET-avid, and, often we say, "Oh, we found the lesion in the ovary and the PET scan was negative." That doesn't matter. In an NMDA-receptor antibody patient, if you find the lesion in the ovary, you need to make certain it's not a teratoma, because PET scans will not necessarily pick up a teratoma - it's not an avid malignancy. So, if the patient is a smoker and I suspect small-cell lung cancer, so I would always get the PET scan. If I have a patient with a high-risk antibody like PCA1 (or anti-Yo) and I didn't really find the tumor with the CT chest, abdomen, and pelvis and the mammogram, I will always get the PET scan. Same for the patients with the smoking history. I will also say that, sometimes, we forget other malignancies. So, for example, we have neuronal intermediate filament antibodies (so, ANNA-3 antibodies), and some of them will have Merkel cell. So, depending on the patient, on the antibody, and if we didn't find anything else, I would do a skin check. If they have GI symptoms, I would look for the GI tumor as well. So, even though the basics are what I mentioned, I will adapt depending on the patient symptoms. And all of these patients should have age-appropriate cancer screening, so if they didn't have a colonoscopy, they will have to have a colonoscopy. So, this is part of the main things. And then, the question for me that always comes up is, "Who is the person that you're going to keep on repeating the screen?" And then, practically, if you have a low-risk paraneoplastic antibody that comes (let's say LGI1), we know it's a low risk, so I would actually do the cancer screening - I will look for the thymoma once, and then that would be it. But if you have a patient with a high-risk paraneoplastic antibody (let's say ANNA-1 [or anti-Hu] or anti-Yo [anti-PCA1]), these are the patients that I will keep on screening - and then I will do every four to six months for two years (that's the current recommendation), but I will probably continue yearly after. And then, we need to also remember that whenever you have a neurological relapse, that's exactly when you need to be looking for the cancer as well - so, you must be thinking that the idea is that maybe you have the immunological relapse because there is cancer somewhere. So, these are the types of things that I kind of adapt to specific patients. But I think when we're not certain, broad screening is what we need. And then, again, the PET scan - for me, it's a great test, but we need to know its limitations. So, that's the other thing that comes up a lot in the phone calls or in the patients that I see that we do a PET scan - but practically, it's not good for some of the malignancies that we're looking for.

Dr Grouse: That's really great to point out, and I'm glad you brought up the risk level of the particular syndrome. You have a great table in your article that summarizes the risk level of some of the various syndromes - so, you know, just a reminder for everyone to check that out if you want to have more information about this and how this applies to the screening - so very helpful. What is the easiest mistake to make, and also maybe to avoid, when treating patients with paraneoplastic neurologic disorders?

Dr Zekeridou: That's a great question, actually. So, there are two things here. One is that we need to be thinking about paraneoplastic neurological syndromes, because if you don't think about them, then you don't look for them. So that's the one thing. So, patients that come with a subacute onset of neurological dysfunction - they have systemic features, or they are smokers, they have autoimmunity in the family (all those things) – like, we need to be thinking about paraneoplastic neurological syndromes. On the other side, we also see a little bit more of overdiagnosis that's coming in the later years. So, one of the things that we see a lot is that we kind of have difficulties with the interpretation of the neural antibodies - so, sometimes, we will get a neural antibody, and then it will not fit, but we will base our diagnosis on the neural antibody presence. And then, some neural antibodies are great - we don't really see false-positives - but some of them are not great and we do see false-positives. So, for me, the main thing that I would say is that we need to have a clinical suspicion - we're treating the patient and the clinical syndrome if it is compatible with a paraneoplastic neurological disorder, and then the neural antibodies are the ones that are going to help us, like, diagnose or point to a cancer - but we are really treating the patient. And then, if we give a treatment and it doesn't make sense how the patient evolves, we actually need to reassess the diagnosis, because we do have both overdiagnosis, but also we have underdiagnosed in patients that it's not suspected - so I think it's kind of the increased awareness that helps, but we also need to be going back always to the clinical manifestations of the patient.

Dr Grouse: Really great points to make, and thank you so much for that. What is the most common misconception you've encountered in treating patients with paraneoplastic disorders?

Dr Zekeridou: So, one of the things that we see a lot is that patients wait to be treated - even with high suspicion of paraneoplastic neurological syndromes - until we have the neural antibodies, and sometimes, if the neural antibodies are negative, we have patients that are not given a paraneoplastic neurological syndrome or autoimmune neurological syndrome diagnosis because of the negativity of the antibodies. So, for me, one of the main things is that the patients actually fit clinically with a paraneoplastic neurological syndrome - and there are scores that can help us, clinical manifestations that can actually help us make this diagnosis. We need to be looking for the cancer and treating them, regardless of the presence of the antibody. Some patients will not have the antibodies for weeks. The second aspect to this is that, often, we want to say, "Oh, it's a paraneoplastic neurological syndrome. They will treat the cancer and, like, that's the oncologist's job." But, practically, I think that the neurologist will really need to be involved with this. I think the patients need treatment of the immune response and treatment of the tumor. So, I think we are part of the treatment team for these patients and it's not only the oncologists that are treating the tumor.

Dr Grouse: Where do you think the next big breakthrough in this area will be?

Dr Zekeridou: Where I hope it would be - and I'm hoping that it's actually what it is going to be – is, really, better understanding and treating the classic paraneoplastic neurological diseases, that they are T-cell mediated disorders that lead to neural cell distraction, and we don't have good treatments for these patients and we cannot get any improvement. So, there is a lot of research going on there. How can we prevent? How can we treat? But, I think that would be the next big milestone for us, because the antibody-mediated diseases - so we now have a lot of good treatments. Like NMDA-receptor encephalitis, AMPAR encephalitides - these antibody-mediated disorders, we have good treatments. The disorders that the antibodies are biomarkers - and they are the cytotoxic diseases, the effectors of the autoimmunity - we don't. So, that's where I hope and think our breakthrough will be.

Dr Grouse: Definitely hoping to see more advancements in this area and already, I think, very quickly developing field. So, I wanted to talk a little bit more about you and what brought you to this area of neurology I think which most of us find to be a very fascinating field that would love to hear more about what brought you to it. How did you become interested in this area of neurology?

Dr Zekeridou: I did my medical school in Greece. So, in Greece, towards the end of the sixth year, you need to decide what your specialty would be, and for the life of me, I could not decide between oncology and neurology - I was changing my mind all the time. And then, I decided that the diagnosis is more important to me in terms of a physician - that's why I went more with neurology and I was clear on my choice. So, practically, then, I went and did my residence in Switzerland, and something happened and I found myself in the outpatient autoimmune neurology multiple sclerosis clinic for a year, and it was evident to me that this is my passion. Like, the multiple sclerosis, I thought was a great disease, but it was the cases that they were not multiple sclerosis, that they were the ones that they were the most fascinating for me. So, then, I did my peripheral nerve year - so even more, it was clear for me that this is the immune system interactions, the cancer, and the neurological symptoms - that's what I wanted to do. And practically, I pursued a fellowship in Lyon in the French Reference Center for Paraneoplastic Diseases, and I was sold. There was nothing else for me. So, eventually I came here at Mayo (and then I stayed) - but it was very clear, even since the beginning - and I really found something that combined both of my passions even from medical school.

Dr Grouse: What are you most excited about in this field? And, specifically, you know, what might you impart to other trainees who are thinking about choosing this field for themselves?

Dr Zekeridou: So, I think that there are many things. So, autoimmune neurology or paraneoplastic neurological syndromes, they can affect every level of the neuraxis, so, practically, your clinician, that we see everything - we'll see central nervous system, peripheral nervous system, neuromuscular junction – so, that's actually very fascinating for me. The second part of it is that we have diseases that we can actually treat. We see differences in patients that we will intervene and we will really change their disease course. And the other thing for me is all the research that is ongoing. So, practically, the research in paraneoplastic syndromes or neurological immunity is directly translational to the patient - like, we have kind of a bed-to-bedside type of research that is going on. And basic research is important and there is a lot of advances, but you can see them directly, like, being translated in patients - so, essentially, the research is directly translational to clinic, and that makes it very exciting.

Dr Grouse: I think that your excitement about this field is very inspirational and will hopefully inspire many future trainees who are interested in this field. So, when you're not learning more about paraneoplastic syndromes and their treatment and diagnosis, what else do you like to do? Tell us something about your outside interests.

Dr Zekeridou: So, again, I come from a very diverse background and the way that I arrived in the states, but, I really like traveling. So, we would travel a lot lately. We travel more in Greece, because when you're coming from Greece and you're not living there, your summers are always there - but we try to explore different places there. And one of my main things and passions that I like is, essentially, cooking. So that relaxes me, that helps me - cooking and having friends over – so, that's my favorite thing of doing outside of work.

Dr Grouse: Well, I have to say it's hard right now to imagine anything more fun than traveling and enjoying good food and Greece. So, I think your hobby seems like one we can all get behind.

Dr Zekeridou: It's relaxing the mind.

Dr Grouse: Yes, yes. This has been a really great discussion on what I think is a very interesting area of neurology, and we really appreciate you taking the time to talk with us today.

Dr Zekeridou: Thank you so much for having me. It was great talking to you.

Dr Grouse: Again, today, I've been interviewing Dr Anastasia Zekeridou, whose article on classical paraneoplastic neurologic disorders appears in our most recent issue of Continuum on autoimmune neurology. Be sure to check out Continuum Audio episodes from this and other issues. And thank you to our listeners so much for joining us today.

Dr Monteith: This is Dr Teshamae Monteith, Associate Editor of Continuum Audio. If you've enjoyed this episode, you'll love the journal, which is full of in-depth and clinically relevant information important for neurology practitioners. Use this link in the episode notes to learn more and subscribe. AAN members, you can get CME for listening to this interview by completing the evaluation at Continpub.com/audioCME. Thank you for listening to Continuum Audio.

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