Transcription
So thank you very much for the kind invitation. Um, yeah, I will discuss a little bit on the role of the vaccine stabilizer, having a focus on PEG and polysorbate, and what we have learned here from and during the the pandemic with limited access to the to the vaccines.
So I think all allergists have some memories of that date, a date where all media pumps out with the risk of allergic reaction when we started to get some the first mass vaccination in the UK. And I guess all of us thought somehow that we're going to be involved in in some more consultation than usual. And indeed, if you look a little bit also of how the different learned societies reacted, you can see that basically it was pretty heterogeneous in the in the guidelines that were asked. And what what we can say is that very quickly we had the belief that there is a link with the excipients in this kind of allergies. But anyway, if you look among the learned societies, everyone has slightly different guidelines, except for one that was to recommend an allergy consultation. And so maybe to try to understand the role of the excipients in this kind of allergic reaction, the first thing we have to do is to understand how do these vaccines were made. And basically mRNA vaccines are nanoparticles that are made from RNA that is mixed with lipids. And these lipids are also containing the PEG. And so why do we need to to have the PEGs? Basically, when you increase the pH, uh, here, so in the solution, you will promote the production of micelles. And these micelles gonna fuse each uh uh with each other until they reach a stabilized form. And to have a stabilized nanoparticle, you basically need these PEG molecules. So your nanoparticle of vaccines are basically surrounded from PEG or polyethylene glycol molecules.
So what is polyethylene glycol? So first of all, it's not propylene glycol, it's always often confused. Has different names, a macrogol. They are linear polymers that consist of a repeating unit of ethylene oxide. They have different sizes. Uh, the lower sizes are rather liquid than the higher sizes, among 3000 or rather solid. They have been used, as I just mentioned, in the mRNA vaccines as a PEG-2000. And PEGs basically are found everywhere. You find that in cosmetics, you find that in the hyaluronic gels, in food. You have that also in many drugs, namely also in the laxatives. And this is why probably we are very often exposed to that kind of molecules. And we can imagine that we can have some covalently bound molecules and we can start to make IgG, as it was suggested, um, just for with the previous talk. And indeed, you have some papers who have demonstrated or at least suggested, or let's say like that, that anti-PEG IgE exists. And they have tried to set up an assay where they could measure the level of anti-PEG IgE. And this could correlate, if you compare the cases of anaphylaxis and the control ones, where in the controls, you have no Ig or low level of IgE, as as compared to the case of anaphylaxis where you find a higher higher level of anti-PEG IgE. And very interestingly also, in many people, you you have you can find some anti-PEG IgG.
Okay, what you have also to know about PEGs or polyethylene glycol is that they can be found this, uh, structure in the polysorbate. So this is why we have some cross-reactivity with polysorbate. And basically, polysorbate is a hydrophilic ethyl oxide sorbitan that has, so that is constituted with these ethylene glycol molecules and that has also an hydrophobic carboxylic acid. I'm talking of a polysorbate because it's also used in many drugs to stabilize the drugs. So if you think of a protein, many of this protein are actually amphiphilic. And that means that they can aggregate together. And so we have to be careful if we want to maintain the stability and their function to have what we call this kind of surface effect. And that our polysorbate. And by adding, uh, more and more polysorbates, so depending on the amphiphilic activity of the protein, you will be able to generate some kind of micelles and stabilize your protein. And this is why you have different amounts of polysorbate in different drugs. I'm just showing here at least like in the Johnson that use polysorbate to to stabilize his, uh, his, uh, viral bioparticles, or in other vaccines, uh, in infliximabs, in in the context of antibodies, we're also often using polysorbates.
Okay, so that being said, that's why I I talked about CARPA because a lot of people still think that the PEGs or polysorbate can be involved in CARPA reactions. And how does it really works? And the idea is that you have indeed some anti-PEG IgM that can bind directly to these PEG molecules and that can trigger the activation of the complement. And once you have the activation of the complement, that will secondly activate your mast cells and basophils. And you can have what we call this pseudo-allergic reaction. So what evidence do we have to say that CARPA could exist in the context of a polyethylene glycol-backed reaction? Uh, and and this is the, I think, one of the nice studies, although we don't have much repeats of it, who have could show in vitro that if you take a drug that can that contain polysorbate, basically you can provoke an activation of your complement. And this is measured by the soluble C5b-9 complex, the C5b-9 complex attack of the complement. And and this was really specific to the drugs that has, uh, some polysorbate or chromophore. It's also a molecule that is a very linked to the to the polysorbate or PEGs.
Okay, so indeed, we had some allergic reactions. So the number of allergic reactions was always a matter of debate. So exactly how many? This is a nice review that looked at every, uh, uh, every paper that has reported some allergic reaction. And what I want to emphasize, uh, here is to say that it was really heterogeneous. So the only thing I really don't like is the scale because you see the scale between 0 and 100 is so close together that you have the the impression that the number of anaphylaxis was always similar. In fact, it was a very heterogeneous among centers. And so you have some anaphylactic reactions that can go from 100 patients per million doses to only one. And so this was always a matter of debate. And the question was, how do we should manage these people with anaphylactic reactions? And the first thing people tried to do is to do a skin test for PEG or polysorbate. And from that paper, they they concluded that that skin testing for polysorbate or PEGs was only unfortunately very limited, because if you now provoke or try to provoke people who had a positive skin test for for PEG, you had some people who could tolerate the dose, while you have people with negative skin tests who could indeed have a reaction. So the conclusion of this paper is that testing directly with the PEGs or doing skin tests with PEGs is actually pretty limited. And the question obviously that we had is why should we not use directly the vaccine to try to assess the allergic reaction? And, uh, I'm just showing you here the, uh, key position paper on on that topic. And and they recommended basically only to do pre-prick tests, uh, with the vaccine and try to save as much as possible the mRNA vaccines to avoid any waste. And therefore, they were not good recommendations to to try to do such a skin test.
What I can say is that in our experience, skin tests, in particular intradermal reactions, works very nicely. So we can find a very nice positive EDR. And you see for the Moderna vaccine as for as well as for the Pfizer vaccine. And not very surprisingly, you have this nice, uh, also correlation with the polysorbate who can show reactivity. So this is the case of a patient that had an anaphylaxis after taking some laxatives. Should we do a prick-to-prick skin prick test or intradermal reaction? Uh, our opinion is that rather not, because if you look on the all the patients we have tested in our clinic, more than now 134, we found around we found 30 patients that had both skin EDR positive reaction for the Moderna vaccine and for the Pfizer. But you can see only one of this patient had a a prick test that was positive. So I think our data will suggest that if you want to look for sensitization to the vaccine, you should go for an intradermal reaction. This is also, uh, confirmed with basophil activation test. And if you try now to test both vaccines with these patients that are sensitized or have skin positive skin tests for the mRNA vaccines, you you really nicely show that the ones who have a positive skin test have a positive BAT. When you look at CD63 upregulation, and the polysorbate was a little bit less clear, but again, the significance is really, uh, with the, uh, with both mRNA and vaccine. And there is a very nice correlation with the skin test. So if you have a negative skin test, you pro you have a you are very likely to have a negative BAT. But if you have a positive skin test, then you're very likely to have a positive BAT.
So what is the mechanism of this activation? One is to say is to ask the question whether IgE are involved in that. And the the experiment we did, uh, basically, it was to use ibrutinib. And the idea of ibrutinib is that you can selectively inhibit the activation of the basophil that is mediated through the IgE pathway. And in this context, you see if you use anti-IgE, you have a nice upregulation of CD63 expression. And if you use ibrutinib now, you have a significant downregulation. And this is not true if you use a bacterium, they have peptide FMLP. And here with the FMLP, you have absolutely no difference in the level of CD63 expression. So really suggesting that ibrutinib selectively inhibits the IgE pathway. And if you apply ibrutinib on the BAT with the vaccines, you see that you have a significant downregulation that was even more obvious for the Moderna vaccine. So that really suggests that indeed, we make IgE against the vaccine.
So I'm coming back to this, uh, notion because a lot of people think that CARPA and I will explain you a little bit later, are you still involved in the mechanism of allergic reaction in these patients? A simple experiment we tried to to see whether the complement may have a role in the activation of the basophil was simply to take the blood of someone that are vaccine sensitized, to take out the serum, either inactivate the serum by putting it at 30 minutes at 65 degrees or putting it on ice. And then we replace this serum in the BAT of another tube. And we try to do our BAT assay. And what we observe is that, and so it's only one case, but the level of activation in in between all conditions was exactly the same. So this, uh, to our opinion, suggests that in this case, the, uh, the complement is at least not involved in the activation of basophils.
Another thing we we have also tried to test it in the lab is to see whether we can use fresh or cryopreserved vaccines. And, you know, we have this limitation of accessibility to the vaccine. And the question is now, what can we use? And how can we get this vaccine because now we have less and less vaccination, for instance. And so we have tried to look at correlation between freshly harvested vaccines and frozen ones. And you can see here, this is true for the Moderna as well for the Pfizer, you have a very, a nice correlation between the Moderna and Pfizer and the fresh and cryopreserved vaccine. So it suggests that what we can do is basically cryopreserve or stock of vaccine and use that for BAT assay. We even tried, you know, to cryopreserve that different days after we got it. We waited until 16 days. And you see that even if you get the vaccine very late and you froze it two weeks later, it's still efficient and you have exactly the same level of CD63 expression that is induced.
Okay, so why people are not convinced about IgE-mediated anaphylaxis in the context of vaccination? And the main reason is that when you re-challenge them, and that's a this meta-analysis would have looked at all the studies who have tried to do that, basically upon re-challenge, you have very little severe reactions. And the idea is that if you would have an IgE-mediated reaction, it could be that you have you should have a very severe reaction that could be promoted. And actually, it's true that most of the patients that we re-challenge with the vaccine can tolerate it. You you have to be careful, it does not favor severe reactions, but people actually react. So they have some small reactions, but they don't have a major, uh, severe reaction.
So what we have done, uh, in the CHUV with patients we had in the Netherlands, anaphylaxis and we found sensitization, we started to do this five-step induction protocol. And here the idea is to split the dose into five smaller doses. And we have compared a different group of patients. One is the ones who had an anaphylaxis to a component that contained similar excipients than the vaccine, PEG or polysorbate. We have tried to do this also with patients that are sensitized to the mRNA vaccine and we had only an allergic reaction but without criteria for anaphylaxis. We did the same for some of people who had an anaphylaxis. And we also tried this protocol in patients who had a hypersensitivity reaction that were not tolerated up and with challenge despite the fact that they had a negative skin test. And what you can observe is that people that has this prior anaphylaxis component to the component of the mRNA vaccine tolerate it very well without any issues. That is also true in the context of patients with allergic reaction without argument for an anaphylaxis. Now, when the reaction was more severe, what you can observe is that in one case, we had to stop the vaccination process. And in two, we could finish it, but they still had some symptoms. And and the more striking ones is the ones who had negative skin tests who still and still didn't tolerate a 10% re-challenge when we tried this five-step protocol. It didn't really have because one of the two patients we could not finish the vaccination, the other we could finish it, but still had some also a reaction to it.
Is it safe from just an immunization point of view to vaccinate people with a fractional dose? And we measure the cellular immunity of these people who get either 10% fractional dose or two-step dose, 10-90, or this five-step induction protocol. And and what we can observe is that with the booster response, you have similar levels of, uh, uh, upregulation of your antibodies for the SARS-CoV-2 independently of the way you get your vaccine. If it's 100%, if it's a two-step or it's a five-step vaccination protocol. So I think these are also really re-engineering data that we can split the dose to vaccinate people who may have had some allergic reaction.
Okay, I I will, uh, end here. And I will have to thank a lot of people in the CHUV, but also in our diagnostic tools, also Daniela here, we could work a lot with him very successfully. We had also the help of many allergists in the Canton. We provided also some of the patients. And also we had this massive mass center vaccination centers where many people were also involved in identifying patients with allergic reactions. And I thank you for your attention. I'm happy to take some questions. [Applause]
So question from the audience. So I have one. Uh, so we we could see in the in the BAT that actually the linear PEG were never never positive, but actually that the polysorbate 80 was a little bit more cross-reactive with with the compounds. Do you think that the 3D is something important or if could be another factor? So indeed, I think that the three-dimensional construction is really important. And this is explaining why not everyone who has anti-PEG antibodies has anti-polysorbate antibodies. So the cross-reactivity, uh, probably between these two drugs is only, uh, between 30-40%. It's not 100%. So that really suggests that the structural structure of the polysorbate may play a role. I I know also that for the PEG BAT tester, so the PEG for intradermal reaction is really bad. Uh, so we had zero reactivity, almost zero. Uh, so we don't recommend to do it. And indeed, also with the BAT, the PEG was not very useful to, uh, to identify a sensitized patient. Yes, it's sincere. There are a lot of clinicians that have a long experience. Have you never experienced the very same kind of anaphylaxis in several other drugs that have the similar PEG-like structure, like the Doxil, that is the encapsulated doxorubicin, that is exactly similar to this vaccine, or there is the carboxypeptidase, that is again a molecule with a very similar folding? Is is this something already discussed at clinical level? I think it's still a very new topic, to be honest. And, uh, I mean, all the papers are less than 10 years old. And, uh, I think we still have much to learn on the on the exact mechanism and on the cross-reactivity that we can find in between drugs. And the reason why we find it and sometimes yes, sometimes no. But but obviously, this is something we have to consider when we have someone that is a vaccine vaccinated sensitized, and then we, you know, we recommend to the patient to stop all drugs that has a component that may contain excipients that could create cross-reactivity with the PEG of the mRNA vaccine. Yeah. And I remember also one of the first patients tested for for developing this BAT had also cross-reacted with Staxol that used chromophore that is very similar. Then it was really cross-reactivity or something else? We didn't dig it. It's true that we have some patients that are vaccine sensitized without argument for, uh, and quite a lot for polysorbate vaccination. So it's all about hypersensitivity. So it could be that there is also specific antibodies that are just recognized in the context of the mRNA vaccines and not for other drugs. Yes. Thank you for your talk. I have a very practical question. So if you have a patient who shows a positive skin test to to one of the vaccines after having an anaphylactic reaction, you did, um, you could desensitize the patient or to give him the vaccine with your, uh, this is in desensitization protocol. How do you counsel this patient? Um, um, with what do you recommend the patient do? Can they receive drugs that contain polyethylene glycol in the future or polysorbate? Yeah, but it's a very good question. But we recommend at least, you know, we have no restriction for oral drugs because here the the rationale to, you know, have a really a high risk of anaphylaxis to a drug that may contain some PEGs has never really been demonstrated. So but now in the context of an intravenous drug that could contain or contain some polysorbate or PEG molecules, then we advise not to do that and ask us for advice. Yeah, oral medication. There's, in my knowledge, on the best of my knowledge, there's no strong argument to say that we should now start to restrict people to get because the amount of PEG that we get through these oral pills is so low, then we have the stomach where did you know with the acidic pH and may also denature the PEGs. And the it's indeed it's only in the context of a huge amount of laxatives like so that's maybe the only drug, the only drug we we make an exception is the laxative. Exactly. So except when you take so a lot of a lot of PEGs, you