argenx SE (ARGX) Earnings Call Transcript & Summary

Good morning, everyone, and welcome to the argenx Phase III ADAPT-SC Trial Top Line Results Conference Call. [Operator Instructions]. To follow the presentation, we ask that you navigate the slides as directed by argenx management. There will be a question-and-answer session to follow. I would now like to introduce Beth DelGiacco, Vice President of Corporate Communications and Investor Relations at argenx.

Thank you, and good morning to everyone on the call. Earlier today, we issued a press release summarizing our positive Top Line Phase III ADAPT-Subcu Trial Results. The press release and the presentation for today's webcast can be found on our website. On the call today are Tim Van Hauwermeiren, our Chief Executive Officer; and Keith Woods, our Chief Operating Officer. Wim Parys, our Chief Medical Officer, will also be available for the Q&A session following prepared remarks. Before we begin, I'd like to remind you on Slide 2 that forward-looking statements may be presented during this call. These may include statements about our future expectations, clinical development, regulatory time lines, the potential success of our product candidates, financial projections and upcoming milestones. Actual results may differ materially from those indicated by these statements. argenx is not under any obligation to update statements regarding the future or to conform those statements in relation to actual results, unless required by law. I will now turn the call over to Tim.

Thank you, Beth, and good morning to all. We are very happy to share with you today the positive top line results from the Phase III ADAPT-Subcu trial of subcutaneous efgartigimod in patients with generalized myasthenia gravis. We met the primary endpoints, demonstrating noninferiority between subcu efgartigimod and VYVGART IV based on total IgG reduction at day 29, a crucial pharmacodynamic marker that has a linear correlation to MG disease score improvement. Secondary clinical and safety endpoints also confirmed consistency between the subcu and IV products, so we will move forward in filing our BLA by the end of the year. We will get deeper into the trial design and data shortly, but I want to first talk about what this means for patients as we continue to honor our commitment to the gMG community. Patients are at the core of our mission. We have spent the last few years listening to and learning from gMG patients and their supporters, and the feedback we hear is incredibly consistent. Despite currently available medications to control symptoms of gMG, patients experience substantial disease and treatment burden. This extends beyond just physical limitations and can include mental, social and emotional stress as well. They can feel very isolated because even though there are 65,000 adults living in the United States with gMG, each patient experiences the course of their disease and treatment in a unique way. There is no one-size-fits-all. Diagnosis can often be a long journey, and the variability of symptoms can take an emotional toll on patients. Over half of patients have been diagnosed with anxiety or depression on top of their gMG symptoms. A person's ability to live a well-rounded, fulfilling life substantially decreases with gMG. 63% of patients have stopped work or school entirely due to the burden of their disease or treatment. We also learned that gMG patients are in desperate need of new treatment options. Despite taking an average of 2.3 current treatments, over 60% continue to report poor well-being, according to a WHO Index. Last December, we were very proud to receive FDA approval of our first-in-class FcRn blocker, VYVGART. This allowed us to bring a new standard in gMG treatment to patients based on the efficacy and safety profile we demonstrated. Thanks to the hard work and dedication of our global team, we also received approval in Japan just a few weeks later. The U.S. launch is off to a good start. And we reported during our last earnings call that we are trending ahead of our internal plan. Now we intend to bring our subcu product forward globally to complement the VYVGART launch and to be able to deliver the broadest treatment offering in gMG. In developing our subcu products, we aimed for a speed-to-market approach that builds on the repertoire of data we have shown to date. We went to the FDA with a proposed bridging strategy and used the following logic in highlighting our plan. We have shown consistent IgG reduction across all subjects dosed with efgartigimod, it doesn't matter if you're a healthy volunteer or a patient, a linear correlation between IgG reduction and disease score improvements, both on the MG-ADL and gMG scores, and an identical PD effect between a fixed dose of 1,000 milligrams subcu and the 10-milligram per kilogram IV. Basic assumption for bridging IV to subcu was that comparable total IgG reductions would result in comparable efficacy. The FDA aligned with our thinking, and you can see the ADAPT trial design on Slide 7, where we used total IgG reduction as the primary endpoint measure. While we only needed 50 patients to power the primary endpoint, we enrolled 110 gMG patients to meet the FDA's proposed safety requirements. This included 91 acetylcholine receptor antibody-positive patients at 19 antibody negative. All were naive to efgartigimod and had to meet similar inclusion criteria as in ADAPT. After a 2-week screening period, patients were randomized to receive 1 treatment cycle or 4 weekly doses of either VYVGART or subcu efgartigimod. The primary endpoint was taken 1 week after the last dose, and key secondary endpoints were measured throughout the full 10-week trial period. There was no option for re-treatment in this study. And after week 10, patients had the opportunity to roll over into an open-label extension study where they would all receive subcu efgartigimod. 105 of the 110 patients enrolled in ADAPT-Subcu entered the open-label extension study to further support the safety database requirements. We also offered patients in the ADAPT-Plus open-label extension the option to switch over to the subcu open-label extension. Baseline characteristics were generally consistent between the subcu and IV arms and consistent with what we saw in ADAPT. On Slide 8, you can see that we achieved the primary endpoint with a p-value of smaller than 0.0001. There is a near identical overlap of the PD effect between IV and subcu, and the curve should look very familiar to what we have observed in all efgartigimod studies to date. Total IgGs start to go down after the first dose and reached a maximum PD effect 1 week after the fourth dose. We also included the PD curve from ADAPT in this chart to show the consistency. Pathogenic IgGs, while not pictured, showed similar overlapping curves. Slide 9. The trial was not powered for efficacy, but there is great consistency across all measures between the IV and subcu arms in ADAPT-subcu. 69% of both IV and subcu patients achieved at least a 2-point reduction on the MG-ADL score for at least 4 consecutive weeks, and approximately 66% of subcu patients compared to 52% of IV patients achieved at least a 3-point reduction on the QMG score for at least 4 consecutive weeks. Remember that MG-ADL is a patient-reported, physician-documented measure, and QMG is considered more objective with physiological parameters taken. We like to see consistency across both disease scales, which we achieved in this trial. Minimal symptom expression continues to be an important metric in gMG because it means that patients are virtually symptom-free with an MG-ADL of 0 or 1. In ADAPT subcu, across all participants, we saw 37% of subcu patients and 38% of IV patients achieved MSE. On Slide 10, we show the response curves, both MG-ADL and QMG. This is an impressive efficacy profile with regards to speed of onset, depth of response that supports the MSE measure we just discussed. This is also an independent verification of our ADAPT data in a similar patient population. Efgartigimod continues to do what we expect it to do, and we see a similar profile now between the 2 formulations. The safety profile from ADAPT subcu is shown on the next slide. You can see that there's a lot of consistency here as well with ADAPT and nothing too unexpected. We focused on the most frequent adverse events, which were injection site reactions; 18 of 21 were mild, transient and resolved without intervention. The other 3 were moderate: headaches, which were primarily mild; and fatigue, both of which look balanced between the 2 treatment arms; myasthenia gravis or reemergence of symptoms, which is not unexpected in a trial design with this duration and that does not allow for retreatment. These were very small numbers, typically happened at the end of the follow-up period, and all of the patients who rolled over to the OLE were responders when dosed again with efgartigimod. And then diarrhea, falling, urinary tract infections and contusion, which skewed to IV. Overall, we believe we have a very exciting subcu product to add to our broad gMG treatment offering. Our long-term objective is to serve the gMG patients in the most complete and optimal way, and this is a big step towards achieving this. Before I turn the call over to Keith, I would like to take a minute to thank our team who has continued to deliver strong results on plan. This takes nothing short of a full-team, Herculean effort. Keith is now going to share some of the regulatory and commercial considerations for subcu efgartigimod, and we will then open the call for your questions. Keith?

Thanks, Tim. We are very happy to be here today, have passed the first hurdle in our effort to bring subcu efgartigimod to gMG patients. Next slide, please. Our decision to develop subcu efgartigimod has always been about optionality. gMG is a disease that is experienced differently by every patient. So it makes sense that there are different preferences in how people want to be treated. We took this into account when we integrated an individualized dosing approach into our trial designs, but also when we chose to advance both IV and subcu formulations. We believe that having both IV and subcu options allows us to capture variation in how gMG patients want to be treated. As an example, there are patients who prefer not to self-administer or who enjoy going to the infusion center for the social interaction. On the other side, there are patients with busy lives and enjoy the flexibility of shorter administration times. This was our goal when we signed an exclusive partnership with Halozyme in 2019, co-formulating efgartigimod with their enhanced drug delivery technology. The enhanced technology breaks through conventional subcutaneous volume limitations, allowing us to dose our biologic in a simple, single subcutaneous injection. Our Halozyme partnership has proven to be a good strategic decision. We are the only company that is developing an FcRn blocker that can be administered both as an IV infusion and as a single subcutaneous injection. By offering both, we hope to broaden our market opportunity and reach as many gMG patients as possible. I'd like to take a moment to thank the Halozyme team for their collaboration. It has been a true partnership which we believe will position us well for driving long-term value for our key stakeholders globally. With today's positive readout, subcu efgartigimod is set up to be our second product launch within our neuromuscular franchise. Our field teams are already out there today engaging with physicians, patients and payers on VYVGART, and we want the subcu product to complement these efforts and broaden our offering to the gMG community. We have been encouraged by the initial traction that our field teams have gained with VYVGART, proving that there is a real need in the gMG market for new therapies. We shared earlier this month that we are pleased with the broad initial demand from our key stakeholders. And after the first 8 weeks of launch, we are trending ahead of plan. For physicians, we have breadth and depth of prescribers, meaning it's not just a few doctors writing multiple scripts, but a wide cross-section of doctors from both academic and community centers. We are also seeing physicians write their second and third scripts. We see a breadth of patients that aligns with the ADAPT population, some that are on steroids or mestinon alone and some that are more refractory, and everything in between. And our payer draft policies are becoming available, with the majority closely aligned to the VYVGART label, enabling broad use. Our plan is to advance forward with the BLA filing by the end of this year in the U.S. Similar to the regulatory path for VYVGART, Japan and Europe will follow the U.S. at a similar cadence. You will recall that we will be submitting a separate BLA for the subcu product. By coformulating efgartigimod with Halozyme's enhanced technology, we have a completely different product that will have a different BLA, a different brand name and potentially a different price if we choose. We have not made the decision on whether to use our priority review voucher for the subcu submission. But regardless, we currently expect an approval and launch in the U.S. in 2023. We are very excited with where we stand today and our goal to bring broad product offerings to patients, capturing individual preferences around delivery and dosing schedules, while setting a new standard in efficacy and safety. Specifically, with VYVGART, we have the first FcRn blocker on the market. The early launch dynamics show broad support and demand from physicians, patients and payers. VYVGART has an individualized dosing approach based on treatment cycles. We are also evaluating alternative dose schedules with ADAPT-NXT for patients who may benefit from more continuous dosing. This allows us to further individualize our approach in reaching gMG patients. We showed today that we have a subcu product with a consistent efficacy and safety profile. Patients can choose the delivery option they prefer and not have to sacrifice response in doing so. And we are investing in the future delivery vehicles and formulations. Whether it's a prefilled syringe or an auto-injector, we know that we cannot stop innovating if we want to continue to reach more patients. I mentioned at the start that with these data, we have passed our first hurdle in bringing a subcu option to gMG patients, but we have also passed a hurdle as we look ahead to our broader efgartigimod pipeline. We hope to leverage subcu efgartigimod across multiple indications and franchises, allowing us to bring optionality to more patient communities within hematology, dermatology or kidney disease. This is our long-term vision to bring efgartigimod to as many autoimmune patients worldwide, and we took an important step forward today. With that, I will turn the call over for your questions. Operator?

[Operator Instructions]. And your first question comes from the line of Derek Archila from Wells Fargo.

Congrats on the data. So just 2 quick ones from us. So maybe first, can you just kind of expand on the MG or the worsening MG symptoms? And I guess maybe your thoughts onto why we didn't see it in the IV treatment arm? And then, Keith, I just want to kind of get your thoughts in terms of the split between your view on the usage of subcu versus IV, maybe not just in MG, but kind of broadly across all the indications, like what do you think the utilization rates of those 2 presentations will be?

Thank you, Derek. Let me start with question number one. That's a very simple one. The trial design is such that we can only give the patient one treatment cycle. So at the end of the 10-week period, it's natural that you see worsening of symptoms. And that is basically at the physician discretion whether or not to report such worsening. So I would like to draw your attention to the fact those are really small numbers and nothing out of what is to be expected. Keith, up to you for question number two?

Yes. Thanks for the question, Derek. So we have done market research with KOLs that treat gMG. And in that patient population, we've heard that they believe the split will be somewhere around 70% subcu, 30% IV. But certainly, they're pleased to have both options available for their patients, but also it can affect payers and out-of-pocket expense for patients. When it comes to the other indications, we have not done the market research on that yet. So it would be inappropriate for me to comment on that. Remember, though, we are using both subcutaneous and IV formulations in our ITP study, and we use subcutaneous in Pemphigus and in CIDP.

Your next question comes from the line of Akash Tewari from Jefferies.

So HYQVIA was associated with increased ADAs in chronically dosed patients. Have you seen any ADAs in your study, either in the subcu or the IV arm? And if so, do they have an impact on efficacy? And then in your Phase III ADAPT trial, it looks like worsening MG was also reported as an AE. What were the overall rates of MG worsening in ADAPT? What time points did they occur? And how did that compare with the study that you reported today?

Yes. Thank you, Akash. On the topic of ADA, these are top line data. We don't have the ADA data yet of this specific study. We will, of course, report this data later in the year at a medical conference. But just remember, we have a significant data set now for ADA of efgartigimod across healthy volunteers and patients, and there is not such a thing like an ADA signal, nor in healthy volunteers nor in patients. So we anticipate this is going to be exactly the same case in [Audio Gap]. Whether you look at the REGAIN study, the ADAPT study, this study, you do see, of course, MG worsening towards the end of the treatment cycle between the treatments. And I do not know the number by heart from the ADAPT study, but it was clearly there, both in placebo and active. So this is nothing out of the ordinary.

Your next question comes from the line of Tazeen Ahmad from Bank of America.

Congrats on the great data. I was just curious as to what you think the results of this study mean on a go-forward basis, not only for the additional indications that you're looking at, but does this open up the potential of looking at other indications that you might not have been sure about before? And then I have a follow-up.

Thank you for the question, Tazeen. Thanks for being with us today. This is a very powerful subcu product execution, right, I mean if you look at the PD profile, if you look at the efficacy safety profile. Maybe, Keith, you want to expand a little bit on how does this opening up our options going forward in building out the efgartigimod franchise?

Yes, happy to do so, Tim. So Tazeen, what this gives is the optionality for patients that do not want to go into the infusion center. Maybe it's from a convenience point of view, maybe it's from a location point of view. You also have patients that are not going to be able to take the time out of their day to go in for a 1-hour infusion. And now with a self-injectable, the potential to have a self-injectable that takes a minute to 2 minutes to inject, we really think it's going to broaden the overall number of patients that we're going to be able to serve, not just in gMG, but hopefully in the potential other indications of which we're studying. As far as does it open us up to even further, remember, we've shared with you 10 indications that we're already studying efgartigimod in, but we have publicly said we plan to start working in up to 15 by 2025.

Okay. And then, Keith, maybe can you elaborate on how reimbursement for physicians could influence whether they choose to recommend the IV or subcu to their patient population?

Yes. I mean really, if we take a look at a Medicare setting, we would be looking at the IV given in the presence of a health care professional, and that would be billed under Medicare Part B. Whereas a lot of the subcu, if they're going to administer at home, what we hope to have as an option for the subcu where it can be given either in the presence of a health care professional, like we did in the main part of the study, or self-injected at home, like we're doing in the open-label extension, very similar in the CIDP study. That would open up the ability for the subcu to either be -- go through a specialty pharmacy and be billed under Part D, or they could get it in the presence of a health care professional and under Part B. What this has is it has an impact -- potentially has an impact on patients' out-of-pocket expense. And that's why in any situation, I would encourage verification of benefits before there is a decision made on the location of where the patient and what formulation the patient would be treated with.

Your next question comes from the line of Joon Lee from Truist Securities.

Congrats on the positive data. How explicit was the FDA that non-inferiority on IgG reduction a week after the last dose was the approvable endpoint? And what was the margin for non-inferiority? And then I have a follow-up.

Thank you, Joon. Thanks for being with us today. So the non-inferiority margin was 10%. As we said before, that's a typical margin utilized by the FDA. So 10% was the margin. As we discussed previously, yes, we did, of course, meet with the FDA ahead of the study, triangulating expectations and getting buy-in on this rationale, which we observed. Ultimately, of course, everything depends on the data and is subject to review.

Got it. And so I understand that for U.S. and Japan, this is a separate BLA submission. So you will do that by year-end. But for the EU, is this also a separate submission? Or is it more of a line extension? And if it's the latter, would it be possible to see subcu formulation commercial in the EU ahead of U.S. and Japan?

Keith, do you want to take this question, please?

Yes, happy to, Tim. So you're correct. In the U.S. and in Japan, this will be a separate filing and a separate BLA. In Europe, this will be a line extension. It will be the same brand as VYVGART. It would just be the subcu formulation that's available. Still, even with that, I wouldn't expect that you would see it available prior to it being available in the U.S. Remember that the big thing is going to be not just getting the regulatory approval, but then it would be the negotiation process on a country-by-country basis across Europe, which, as I've shared before, could take anywhere from 12 months to 3 years.

Your next question comes from the line of Matthew Harrison from Morgan Stanley.

I guess first, can you just comment on any other factors beyond the safety database which may impact the filing time line, or any other things that you need to be doing behind the scenes? And then secondly, could you just comment on the scope of the ISRs and how they look versus other Halozyme products?

Thank you, Matthew. Two excellent questions. So really, the rate-limiting factors on the trajectory to BLA submission is the collection and reporting of the safety data. So we said in previous calls publicly that all subjects which we need to have on drug are on drug. So it's now just a waiting game, collecting sufficient exposure data for these patients to then collect, process the data and submit them. So that's really the rate-limiting factors. There are, of course, efficiencies between the IV BLA and the subcu BLA when it comes to, for example, the preclinical section or the CMC section because the manufacturing process is basically identical, except for the final dilution step in case you want to go to an IV product. And when it comes to the ISRs, it's very straightforward. So 21 cases, 18 were mild. This is your typical retina swelling, itching. It resolves spontaneously. And you'll see also a decrease over time in these patients. I would say this is largely in line with other Halozyme-equipped products or even more broadly, subcu-delivered biologics in general. Thanks for the question.

Your next question comes from the line of Yatin Suneja from Guggenheim.

This is Evan on for Yatin. Congrats on the data. One quick one for us. Can you comment on the heterogeneity you've seen in IgG responses with the subcu formulation? Is there anything that can reliably predict the trajectory of the IgG curves? And as a follow-up, do you see any major differences in these curves between the seronegative and seropositive patients?

Yes. So thank you for the question. The IgG reduction curve is very predictable, as we have basically shown for the primary endpoint slide, Slide #8. Actually, your curve is identical to the IV curve. So the dose and the time will perfectly predict what your IgG level reduction is going to look like because of -- or perfectly superimposed. We also said in the prepared notes that the autoantibody title is following exactly the same curve as these total IgG curves. And I can confirm to you that in the seronegative patients, total IgGs behave exactly the way these curves are predicting. Thanks for the question.

Your next question comes from the line of Allison Bratzel from Piper Sandler.

So first, just a clarification on the AE of MG worsening. Was that a protocol-defined adverse event, for example, defined by a certain level of worsening on MG-ADL or related to the use of [ refu ] therapy? Or was this really just an AE that was up to the investigator's discretion?

Yes, it's very much the second one. So I invite you to look at the Slide 10, which shows you the ADL and the QMG scores. You basically see that for both arms, these curves behave identically the same. So it's basically at the discretion of the investigator to call out MG worsening. And that's what happened in a small number of patients in the subcu arm compared to the IV arm. But thanks for the question.

Okay. And then maybe just one other on the injection site reactions. I guess was there a relationship between the speed or time of administration and the type or severity of ISRs? And I think you've kind of talked about a learning curve on the injection technique. So maybe if you could elaborate on that a little bit. Were most ISRs reported in the first couple of weeks of dosing? And how will that evolve as we move to a self-administered subcu efgartigimod?

Yes. But 2 things here in your question which is very interesting. So like all other published data you can find on subcu-delivered biologics and including the Halozyme-equipped biologics, you do see that learning curve that's interesting. So you do see these injection site reactions diminish over time. Actually, they disappear. And then the question is we had the same question internally. Is that the learning curve? Or is there something else happening? We just do not know the answer yet. And stay tuned, I would say, because the open-label extension study is going to be very interesting. Whilst it was an HCP administering the drug in this randomized controlled trial, in the open-label extension, the vast majority of patients opted for the training to learn how to self-administer. And it's going to be interesting to observe whether a self-administration goes hand-in-hand with fewer ISRs or just more ISRs, we don't know yet. So stay tuned.

Your next question comes from the line of Jason Butler from JMP Securities.

Maybe a follow-up on the last one. From the patients that had an ISR in the first cycle, any data so far as to suggest whether or not they're more likely to have another adverse event with subsequent cycles? And then, I guess similarly on efficacy, do you have data yet that supports that, similar to the IV, that there's a robust and durable effect with retreatment with the subcu?

Yes, 2 great questions. On your second question, I can confirm to you, although we need to wait for the final data, that people then who roll over to the open-label extension receiving the second cycle, I mean they perfectly respond the way you would expect them to respond as we have seen for IV. So more data to come, but no surprise there, I would say. And then there's no real pattern for the injection side reactions. It's difficult to predict who is going to have an injection site reaction, how long it's going to last and whether that's going to pop up the next time. General trends are they gradually disappear over time. And then guys, I mean, 18 out of 21 are just mild. There was no need for intervention or a special care. They did basically come and go in a transient fashion with no extra care. So this is very much in line with what we could find back in literature overall.

Your next question comes from the line of Danielle Brill from Raymond James.

Congrats on the data. Just a quick one for me and sort of a follow-up to the last. In the OLE, I'm curious how frequent are you dosing? Do you still have the same 50-day time period between treatment cycles? And are you noticing any trends in the OLE where patients may require treatment sooner?

Thank you, Danielle, and thank you for your questions. So in the open-label extension, we allow retreatment based on clinical evaluation. So there's no fixed forced dosing, unlike ADAPT where we initially wanted to establish the real durability of the effect. Before then, we allowed [ re-able ] dosing in the open-label extension 2 study. Here, basically, you use the drug based on clinical evaluation. So you can figure your next cycle based on clinical need. And stay tuned. We're still collecting these data. We will report on these data going forward at the clinical conference. It's too early to comment on it. But so far, we see behavior perfectly in line with expectations.

Your next question comes from the line of Emily Field from Barclays.

Congrats again on the data. A couple of quick ones from me. Just given that you're also pursuing both formulations in ITP, given the staggered timing of the readout, if you could just confirm the filing strategy across both those formulations. And also whether differential branding will be pursued? And then also, I know you said you're not going to make commentary on pricing between VYVGART and subcutaneous efgartigimod and MG today, but perhaps if you could provide a theoretical framework around why one formulation may be worth pricing at a premium to the other.

I'm going to hand over question 2 to Keith. On ITP, we continue to inform you that the FDA told us they need 2 independent Phase [ III ] trials, so registration trials for submission. That's what we're doing. We adapted in full COVID time to a second study where we used the Halozyme-equipped subcu products to maximize flexibility. And your question is topic of an upcoming FDA interaction, where we will basically continue to calibrate expectations on how these 2 studies jointly can qualify for a submission. Maybe, Keith, do you want to comment on the pricing flexibility which you have with the subcu product versus IV?

Yes, happy to do so, Tim. So thanks for the questions. The benefit of this being a combination product with the Halozyme ENHANZE makes it a completely separate BLA, and that allows us to have the potential to price at a different price per milligram. So we don't have to have it similar to that of the IV. Now you asked why -- what could lead to having either a higher price or a lower price. We're going to continue to study this. But I could give you an example and say, in a subcutaneous product that you administer at home, you could have a superior price but have a lower cost overall to the insurance company because they're not paying for a visit or the infusion materials, the nursing time and such. So there's a lot of factors to take into consideration, but we have not made any decision on price, whether we will be at parity, higher or lower at this point.

Your next question comes from the line of Joel Beatty from Baird.

Congrats on the data. The first question is regarding the MG worsening that was reported as AEs. Are you able to look at the clinical efficacy measures and -- that were captured and see whether there were any signals of MG worsening in the subcu arm compared to IV? The averages in the presentation looked great, but curious about signals of worsening. And then second question is on the injection site reactions. It looks great that all but 2 were transient and resolved without treatment. What treatments were used in those 2?

That's a great question. Wim, if you're on the line, I will refer to you for what medication was used for these 2 cases. But first, on your first question, it's an excellent question, and it's the first thing we did. Actually, you do not see any difference between the 2 arms when you objectively look at changes in an ADL or a QMG score when your IgG curves return to baseline. So they nicely track together. And therefore, we believe it was a difference in preference of the investigators to report or not the MG worsening. Wim, can you comment on the type of medication which was used in these few cases?

Yes, can you hear me?

Yes, Wim, we can hear you.

Okay. Great. So you referred to the cases that were called out as myasthenia worsening, right? Well, there was...

No, Wim. It's the injection site reactions. So...

Okay. Sorry. The injection site reactions were treated with fairly simple local -- these were the grade 2s. The grade 1s didn't need any treatment. In the grade 2s, we have local steroids and antihistamine was given. This is the type of treatment, and they resolved.

Thank you, Wim. Thank you.

Your next question comes from the line of Manos Mastorakis from Deutsche Bank.

A couple of quick ones from us, please. Is there any additional color you could give us on the MG launch so far on the patient numbers? And how representative are the HYQVIA prescription data now? And will that improve over time? And just a quick follow-up. How fast do you expect the switching from IV to subcu to occur? And maybe a quick follow-up after that.

Yes, thank you for the question. Thank you for the question. Keith, I will hand over to you for the switching question. On the first question, we can be formal. Let's all wait for the Q1 earnings call for that extra color you're all waiting for. So give it a few more weeks and then we will be ready to talk about it. Keith, you want to give color on expectations around switching behavior from IV to subcu?

Yes. I mean right now, we -- yes, right now, the only situation where we have is the patients that we took from the ADAPT OLE and allowed them to roll over into the subcu OLE. I will call out that not 100% of patients that were on the IV formulation chose to go into the subcu because again, we have different preferences. As far as the speed of which an IV patient was rolled over to subcu, we don't have that information at this point. I think it's going to be on a patient-by-patient basis.

And your next question comes from the line of Charles Pitman from Redburn.

Congrats on the positive results. And so yes, 2 very quick ones from me. I was just wondering if you could elaborate on the triggered or expected milestones for the Halozyme collaboration as a result of this readout? And then secondly, just on where -- given the expected regulatory process, when might we expect a decision from you guys on the potential use of your PRV?

Yes. These are 2 quick questions indeed. So there's no milestone associated with this data readout. The way you have to think about milestones and other payments to our partner, Halozyme, is in line with what is publicly known about their licensing deal. So our deal is not any different. So expect something around approval instead of readout. And then secondly, the PRV voucher is an important business decision which we will be taking later this year. So stay tuned. It is something which is on our plate. And we have 2 very exciting options where we could play the PRV voucher. One would be to accelerate the subcu product to our MG market or to accelerate efgartigimod into hopefully its future CIDP market. So stay tuned on that decision, and thank you for the question.

And there are no further questions at this time. This concludes today's conference call. Thank you for your participation. You may now disconnect.