Q1 2024 Voyager Therapeutics Inc Earnings Call

Participants

Alfred W. Sandrock; President, CEO & Director; Voyager Therapeutics, Inc.

Robin Swartz; COO, Principal Financial & Accounting Officer and Acting Chief Business Officer; Voyager Therapeutics, Inc.

Toby Ferguson; Chief Medical Officer; Voyager Therapeutics, Inc.

Todd Carter; Chief Scientific Officer; Voyager Therapeutics, Inc.

Trista Morrison; Chief Corporate Affairs Officer & Chief of Staff to the CEO; Voyager Therapeutics, Inc.

David Timothy Hoang; Research Analyst; Citigroup Inc., Research Division

Jack Kilgannon Allen; Senior Research Analyst; Robert W. Baird & Co. Incorporated, Research Division

Joon So Lee; VP; Truist Securities, Inc., Research Division

Laura Kathryn Chico; SVP of Equity Research; Wedbush Securities Inc., Research Division

Mahdi Goudarzi; Biotech Equity Research Associate; Truist Securities, Inc., Research Division

Patrick Ralph Trucchio; MD of Equity Research & Senior Healthcare Analyst; H.C. Wainwright & Co, LLC, Research Division

Philip M. Nadeau; MD & Senior Research Analyst; TD Cowen, Research Division

Ry Roger Forseth; Research Analyst; Guggenheim Securities, LLC, Research Division

Sumant Satchidanand Kulkarni; Analyst; Canaccord Genuity Corp., Research Division

Unidentified Analyst

Yanan Zhu; Senior Equity Analyst; Wells Fargo Securities, LLC, Research Division

Presentation

Operator

Good afternoon, and welcome to Voyager Therapeutics First Quarter 2024 Financial Results Conference Call. (Operator Instructions) Please note that today's conference is being recorded. A replay of today's call will be available on the Investors section of the company's website approximately 2 hours after completion of this call.
I would now like to turn the call over to Trista Morrison, Chief Corporate Affairs Officer.

Trista Morrison

Thank you, and good afternoon. We issued our first quarter 2024 financial results press release this afternoon. The press release and 10-Q are available on our website. Joining me on today's call are Dr. Al Sandrock, our Chief Executive Officer; Dr. Toby Ferguson, our Chief Medical Officer; and Dr. Todd Carter, our Chief Scientific Officer. We will also be joined for the Q&A portion of the call by our Chief Operating Officer and Principal Financial Officer, Robin Swartz.
Before we get started, I would like to remind everyone that during this call, Voyager representatives may make forward-looking statements, as noted in Slide 2 of today's deck. These statements are based on our current expectations and beliefs. They are subject to risks and uncertainties, and our actual results may differ materially. I encourage you to consult the risk factors discussed in our SEC filings, which are available on our website.
And now I will turn the call over to Al.

Alfred W. Sandrock

Thank you, Trista, and good afternoon, everyone. Please turn to Slide 3. I'd like to start by thanking the Voyager team for their dedication to creating transformative genetic medicines. We made tremendous progress advancing these medicines in the first quarter. We just announced that we have obtained IND clearance for our anti-tau antibody, VY-TAU01, for Alzheimer's disease, and we expect to announce the dosing of the first subject in a single ascending dose trial in healthy volunteers in the coming week or so.
Our gene therapy pipeline also advanced during the quarter with development candidates selected in the GBA1 and Friedreich's Ataxia programs partnered with Neurocrine. These programs, along with our wholly owned SOD1-ALS program, are advancing towards IND filings in 2025.
In March, we appointed Dr. Toby Ferguson as our Chief Medical Officer. Toby is an exceptional biotech executive with deep experience advancing novel therapies for CNS diseases. This includes tofersen, the first genetically targeted therapy to be FDA-approved for SOD1-ALS and the first treatment to receive accelerated approval based on plasma neurofilament light chain response. Toby has hit the ground running, and we look forward to his leadership of our emerging clinical portfolio.
In January, we announced an expansion of our relationship with Novartis through a new strategic collaboration and capsid license agreement to advance potential gene therapies for Huntington's disease and spinal muscular atrophy. This agreement, together with the public offering we completed in January, brought $200 million of total consideration to Voyager in the first quarter. This bolstered our balance sheet and extended our runway into 2027, and we expect that it will enable us to achieve multiple clinical data readouts.
Finally, we presented a robust set of data at the recent AD/PD and ASGCT meetings, including data on our multiple tau-targeting programs in our second-generation capsids. Given this significant progress, we believe Voyager is emerging as a leader in neurogenetic medicine.
Our pillars of value are summarized on Slide 4. First, we have a strong pipeline of 4 wholly owned and 13 partnered programs with the first expected to enter clinical trials in the coming weeks and the potential for 3 more to follow next year.
Second, we have an industry-leading platform designed to overcome the delivery challenges inherent to CNS gene therapies. Our TRACER platform enables us to create novel capsids that, following IV delivery, harness the extensive cerebrovasculature to enable widespread payload distribution across multiple brain regions and cell types. These capsids have demonstrated translatability in multiple species. And have enabled the selection of multiple development candidates in our wholly owned and partnered gene therapy programs.
Third, we have blue-chip partnerships anchored by TRACER's potential to transform the treatment of CNS diseases. In addition to Neurocrine, our partners include Novartis and Alexion. In total, our partnered programs could generate up to $8.2 billion in longer-term milestone payments.
Finally, we continue to explore the potential to leverage receptors we have identified to shuttle nonviral genetic medicines into the brain. Ultimately, we aim to expand from gene therapy and antibodies into other modalities of neurogenetic medicine, broadening our impact.
With that, I'll turn the call over to Toby.

Toby Ferguson

Thank you, Al, and good afternoon. Please turn to Slide 5. This slide summarizes the 4 wholly owned programs and our 13 partnered programs that Al mentioned earlier. Part of what attracted me to Voyager is that these programs are focused on targets validated by human biology and human genetics. As a drug developer and former practicing neurologist, I've dedicated my career to improving the lives of people living with neurologic diseases.
And while our understanding of the genetic and biological basis of CNS diseases has advanced considerably, translating that understanding to new therapies has been hindered by challenges with crossing the blood-brain barrier. I believe that the progress that Voyager has made in this regard is transformative and provides an unprecedented opportunity to redefine the treatment of CNS diseases. I'm delighted to join the company as we prepare to enter the clinic and realize the full potential of our pipeline of neurogenetic medicines.
Turning to Slide 6. I want to focus for a moment on 2 of our wholly owned programs that target tau. We believe tau is a critically important target for the treatment of Alzheimer's disease. The presence of tau pathology in the brain is a cardinal feature of AD. Further, the sped-up tau pathology through the brain closely correlates with clinical decline and can be visualized with tau PET imaging.
Importantly, recent third-party clinical data generated using an intrathecally administered tau ASO have shown that reducing tau was associated with favorable trends on clinical outcomes. As Al mentioned, we're excited to announce that VY-TAU01, our anti-tau monoclonal antibody, obtained IND clearance. And we look forward to announcing, in the coming weeks, the initiation of a single ascending dose trial in healthy volunteers. I'll talk more about that trial in a moment.
First, a bit of background on this program. VY-TAU01 aims to inhibit the cell-to-cell spread of the (inaudible) out in the brain. In contrast to third-party anti-tau antibody approaches that have targeted the intrinsical and have been unsuccessful in the clinic. VY-TAU01 targets the (inaudible). We believe the epitope matters. In a preclinical in-vivo model of tau spread, the [myriad] surrogate of VY-TAU01 inhibited tau spread by approximately 70%, with internally directed antibodies have no significant effect. This indicates the negative predictive value of this model.
We look forward to establishing whether or not it has positive predictive value as we advance into clinical trials. Importantly, and in parallel, we are progressing a tau silencing gene therapy approach intended to inhibit the production of tau protein. This program deploys a tau-targeted SRNA packaged into an IV administered TRACER capsid.
Using this approach, we've demonstrated robust reductions and tau mRNA and protein across the brain by a single IV administration and mice expressing human tau. We believe this program has the potential to provide a transformative single-dose treatment for Alzheimer's disease. We anticipate filing an IND in 2026.
Turning to Slide 7. As I mentioned, we anticipate the announcement dosing of the first subject in our single-ascending dose trial, VY-TAU01 in the coming weeks. This will be a single-site study in which we expect to enroll approximately 48 participants. The primary aim of the to generate initial safety and PK data that will form a subsequent multiple ascending dose trial. We expect to conduct the multiple ascending dose trial participants with early Alzheimer's disease. We expect to initiate this trial next year and generate initial tau PET imaging data in 2026. That has the potential to show slowing of tau spread.
Turning to Slide 8. In addition to our programs targeting tau, we are also advancing 3 gene therapy programs for which we expect to file INDs next year. They include our wholly owned SOD1-silencing program targeting the genetic cause of SOD1-ALS, the Neurocrine partnered GBA1 gene replacement program targeting the genetic cause of Friedreich's Ataxia.
And the Neurocrine partnered GBA1 gene replacement program. Mutations in GBA1 represent both one of the most common genetic cause of Parkinson's disease as well as the cause of other GBA1-related diseases. Each of these programs leverages an IV-administered, blood-brain barrier, TRACER capsid and has the potential to provide a single dose disease-modifying treatment. We look forward to advancing these promising suite of programs in the clinic.
With that, I'll turn the call over to Todd.

Todd Carter

Thanks, Toby. Please turn to Slide 9. In support of our advancing gene therapy pipeline, we were pleased to present a robust set of data on the potential clinical translatability manufacturing and overall performance of our TRACER capsids at the American Society of Gene and Cell Therapy Annual Meeting last week.
Voyager scientists presented a total of 12 abstracts at the meeting, and I'd like to review a few highlights. First, we presented new data on our second-generation IV-delivered TRACER capsids. This session was standing room only with a line out of the door and down the hall, which I think speaks to the high level of interest in novel capsids engineered to cross the blood-brain barrier.
Our second-generation capsids should further enhance blood-brain barrier penetrants and reduced liver expression compared to our own first-generation TRACE-derived capsids. These second-gen capsids demonstrated a robust transduction of 50% to 75% of cells across diverse brain regions, with upwards of 95% transduction in certain key cell types, such as Purkinje neurons, at a clinically relevant dose of 3x10 13 vector genomes per kilogram. This also included transduction of 98% of dopaminergic neurons at the substantia nigra and over 80% of spinal motor neurons.
Importantly, our TRACER capsids have enabled selection of development candidates for the 3 lead gene therapy programs that Toby distribute. We presented data at ASGCT on VY-9323, our wholly owned SOD1-silencing gene therapy, which uses a second-generation TRACER capsid. The data demonstrated that a single IV dose of VY-9323 at the 3E13 vector genomes per kilogram dose reduced SOD1 mRNA by up to 80% in spinal cord motor neurons in nonhuman primates.
Finally, as part of our strategy to mitigate the risks of developing TRACER capsid-derived product candidates and maximize their probability of success in the clinic, Voyager has been working to identify the receptors that mediate the delivery of these capsids into the CNS and confirm their expression in humans.
At ASGCT, we identified tissue nonspecific alkaline phosphatase, or ALPL, formerly known as receptor X, as the highly conserved receptor expressed on brain vasculature that mediates the delivery of TRACER capsids VCAP-101 and 102 across the blood-brain barrier. These capsids bind human, primate and neurine ALPL isoforms, further strengthening our confidence in the clinical potential of TRACER capsids.
More broadly, these data establish ALPL as a novel brain delivery shuttle. And we are exploring the opportunity to leverage this receptor to deliver multiple therapeutic modalities across the blood-brain barrier. We look forward to sharing these data in the future. Collectively, the data package we presented at ASGCT represents the most extensive validation to date of the potential clinical translatability of our TRACER capsids. And we look forward to evaluating their ability to transform the course of a broad range of neurological diseases.
I will now turn the call back over to Al.

Alfred W. Sandrock

Thanks, Todd. Turning to Slide 10. You can see Voyager has had an incredibly strong start to the year. As I mentioned before, this would not be possible without the hard work and dedication of our employees. I know many of them are listening, so I want to say, again, thank you. With a robust slate of upcoming clinical milestones, a maturing partnership portfolio and cash runway into 2027, we believe Voyager is poised to drive significant value over both the near and long term.
With that, we will open the call for questions. Operator?

Question and Answer Session

Operator

(Operator Instructions) Our first question comes from the line of Joon Lee of Truist Securities.

Mahdi Goudarzi

Congrats on the great progress. This is Mahdi on for Joon. Last week at ASGCT, you showed great data related to a Receptor X, ALPL. So could you please elaborate on the ways that you are planning to use this knowledge for delivery of the other modalities to CNS? Specifically, do you think antisense oligos and LMPs could see similar levels of transcytosis seen with AAVs?

Alfred W. Sandrock

Yes. Thanks for the question. This is Al Sandrock. So briefly, we know that these receptors mediate the transport of these very large AAV capsids across the BBB. And what we're going to do now is to make ligands against the receptor, conjugate them to various macro molecules to see if we can get them to cross the BBB. We believe by transcytosis. And the range of molecules we could look at include protein therapeutics as well as oligonucleotides and we're progressing those experiments as we speak. Todd?

Todd Carter

Thanks, Al. So we are looking at a variety of modalities. As Al indicated, we're looking at antibodies, oligos, other sorts of proteins. Al mentioned that we're in the process of identifying ligands, and we have identified some ligands. And we're looking forward in the future to hopefully sharing some of those data when we're ready to.

Operator

Our next question comes from the line of Jack Allen of Baird.

Jack Kilgannon Allen

Congratulations on the progress. I wanted to ask about some of the work you presented at ASGCT around the optimization of manufacturing. How are you thinking about optimizing manufacturing before you bring candidates into the clinic with your gene therapies? And what do you expect the benefits will be as it relates to COGS of your more potent gene therapies as well?

Alfred W. Sandrock

Well, I'll start and I'll ask Todd to help here. So we're going to be planning to use HEK293 cells to manufacture these products. We have a very robust internal technical operations team and part of the development candidate selection, we assess manufacturability, both as well as the downstream as well as upstream processes. And of course, we're going to be verifying percentage of full capsids, partially full capsids as well as anti-capsids. And so we assess manufacturability as part of the development candidate selection. Todd?

Todd Carter

So as Al mentioned, we do have that manufacturability is a key component. It's actually part of our whole assessment of our novel capsids as we identify them. In each case, the payload can make a difference so that for any given program, we have to establish the manufacturability with the capsid in question and the particular payload for the disease indication as well.
All that goes into our assessment, and we begin with research-grade material. And then once we develop the settlement candidate, then we proceed to the process development to move that into manufacturability. You also asked a question about COGS. And of course, it's not exactly necessarily a 1:1 trade-off.
But you can imagine, as we're looking with our novel capsids that have a potency approximately about an order of magnitude greater than what the dose is currently used in the clinic, we expect to see substantial savings because we need much less material to deliver the same level or actually greater levels of delivery to the CNS than the conventional capsids.

Alfred W. Sandrock

Yes. And I would just add, Jack, that in addition to the lower doses, what we note is that we're going to transfer the process to a CDMO for manufacturing. And the CDMO world has really come up to speed in terms of scalability. We're now seeing scale. And every time you increase the scale, we actually reduce the cost. So -- and at the pace that it's growing, we expect to see continued advancement in that area as well.

Jack Kilgannon Allen

That's great. Can I just ask one final question on that? I know we haven't really gotten this far in the gene therapy space, but how does the shelf life of these products play a role when you think about the commercial applicability of this manufacturing scale here?

Alfred W. Sandrock

Shelf life. Wow, that's a question I hadn't thought about yet. But anybody on here has an answer to that?

Todd Carter

So we do assess the shelf life. And of course, for a gene therapy, we typically would need to require to be held at particular cold temperatures. All that is part of the evaluation for stability, both short term and long term. So that's an important part of our manufacturability and our process development.

Operator

Our next question comes from the line of Patrick Trucchio of H.C. Wainwright & Co.

Patrick Ralph Trucchio

Congrats on all the progress. Just a couple of follow-up questions for me. The first is, I'm wondering if you can discuss any potential read-through that you'll be looking for from the advisory committee meeting on June 10 regarding donanemab in Alzheimer's disease to your Alzheimer's programs, and then separately, just a follow-up on the ASGCT data, specifically the data in human tau mouse model that showed reduction in tau mRNA levels up to 90% and 50% to 70% reduction in tau protein. Can you tell us how this data compare with prior-generation capsids and how the data may support advancement of tau silencing gene therapy IND in 2026?

Alfred W. Sandrock

Thanks, Patrick. I'll answer the first question, and maybe I'll ask Todd to answer the second one. On the first question, well, it will be a very interesting advisory committee. We do have a vectorized anti-amyloid program in our pipeline as well. So we're watching that advisory committee with interest. I think a lot of the questions might be unique to donanemab and may not pertain very much to our program. Nevertheless, there might be some important features.
For example, what are the outcome measures that are going to be important for approval. And of course, that's always something that we need to keep an eye on. But that's down the line for us. We have to get into the clinic first. But -- so that's the kind of thing we may be paying attention to, but it will be an interesting meeting. Todd?

Todd Carter

So on our tau knockdown program, the data that you're referring to, we showed some at AD/PD and also at ASGCT. The knockdown in the mouse was with a mouse-capable capsid. So we used that really to assess the payload and also to hopefully demonstrate, and we feel that we did, that it's -- the payload has the ability to knock down tau, both mRNA and protein at a clinically relevant dose. So we think that, that's what we showed in those mouse studies. With regard to the payload, we were able to see a well-tolerated and safe dose in those animals, delivering sufficient vector to the brain. And that we saw a quite remarkable knockdown of the mRNA in those animals. So it's building that proof of concept for the knockdown, and we're moving forward now and evaluating the novel capsids for nonhuman primates and humans with the payloads in question. So we're looking forward to sharing more of that in the future.

Operator

Our next question comes from the line of Philip Nadeau of TD Cowen.

Philip M. Nadeau

Congrats on the progress. First, a couple on VY-TAU01. Have you disclosed what doses you are going to be exploring in the single ascending dose trial? And can you talk a little bit how you're going to use the pharmacokinetic data that you gathered to determine what doses should be explored in the MAD trial. How will you guess -- extrapolate from the single dose to the multiple doses and particularly for brain peripheral versus maybe crossing the blood-brain barrier?

Toby Ferguson

Thanks for the call. This is Toby. We haven't disclosed our doses, but broadly speaking, we've examined our candidates in our preclinical model of tau spread, where we've shown that we see reduction by about 70% of the spread of pathologic tau in our mouse models. In addition, we've done preclinical work in primates, I think -- and fundamentally, this is a single ascending dose study in about 48 patients over multiple cohorts.
We expect, based on that data, to get both, of course, safety information as well as PK information on BBB that we think we can appropriately translate into doses for the MAD in mid-2025, whether we want to aim to estimate sort of the underlying exposures needed to get appropriate exposure in the brain to treat this.

Alfred W. Sandrock

Yes. And Phil, I may want to add that I mean, based on our preclinical studies, including an NHP, we don't want to anticipate any major surprises. This is likely to be very similar to other monoclonal antibodies and, therefore, the brain-to-plasma ratio will be in the 0.1% to 0.5% range. .
And as Toby said, we know the exposures that we need to get into the brain to inhibit tau spreading in the model that we used to choose the antibody. So that will give you some idea, and of course, we do expect that trial to inform the dose range in the upcoming multiple ascending dose trial.

Philip M. Nadeau

That's really helpful. And then second, on the frataxin candidate, would you be able to disclose anything new about the candidate that was chosen? And anything notable that you'd be willing to tell us about what differentiated that candidate from the others?

Alfred W. Sandrock

Well, so that's a Neurocrine program. And so we're -- we don't want to disclose these things. Suffice it to say that the development candidate we had a set of criteria for the capsid as well as the capsid-plus-payload combination, both in terms of its mechanistic effects in animals as well as manufacturability. And we'll ask Neurocrine to answer your question.

Philip M. Nadeau

Congrats, again, on the progress.

Alfred W. Sandrock

Thank you.

Operator

Our next question comes from the line of Ry Forseth of Guggenheim Securities.

Ry Roger Forseth

This is Ry from Debjit's team at Guggenheim. From the ASGCT data, now with gen-3 technology maturing, where you're able to navigate preexisting neutralizing antibodies, how are you framing the market opportunity expansion given the preclinical profile you're seeing to date?

Alfred W. Sandrock

I'll start, and maybe Toby or Todd can add. But yes, so you noticed that our -- one of our posters that we are looking -- we're leveraging TRACER to see whether we can make modifications to capsids that affect immunogenicity. And by that, what we're doing is we're looking to see whether preexisting antibodies in humans can affect combined to the capsids, actually, and therefore, affect how they perform in the clinic. And so obviously, if we can find novel capsids that can evade, if you will, the preexisting antibodies, more patients would be available for treatment.
In addition, I would note that we and others are going to be evaluating ways in which we can lower preexisting antibody levels. And as you know, several other companies are investigating the use of various enzymes that can degrade preexisting antibodies. So that will be another way to achieve essentially the same thing, which is to try to get more patients to be eligible for our treatments. Toby?

Toby Ferguson

I would agree with Al. I think the only point I would make in addition is that this may be particularly important in adult populations that may be select pediatric populations with there's not as much of a concern. That may represent some opportunities.

Ry Roger Forseth

Fascinating work.

Operator

Our next question comes from the line of David Hoang of Citigroup.

David Timothy Hoang

First, I just wanted to ask about how you think about the anti-tau antibody fitting into the treatment landscape of Alzheimer's as compared to the tau silencing gene therapy that you also have? What could be the advantages versus maybe disadvantages of each of those modalities?
And then maybe just a second question. Have you interrogated -- or to what extent have you interrogated other transporters besides ALPL for crossing the blood-brain barrier? And if you've done that work, how did ALPL compare to other potential transporters?

Alfred W. Sandrock

So I'll start on the first question. And then Toby, I'll ask Toby to help with that one. And then, Todd, maybe you can answer the second question. So anti-tau versus tau silencing. So very different approaches. Anti-tau, we expect to bind the extracellular forms of tau. And as Todd said earlier, what we're trying to do is to block the spread of pathological tau, which we demonstrated quite nicely in an animal model where we inject human pathological tau into the animals and look at spread. The tau knockdown is a very different -- so that's an antibody that will need to be given on a regular basis. probably on the order of every month or so, every 4 weeks, we anticipate. The tau knockdown is a gene silencing that will be done by gene therapy. So that would be a once and done, essentially.
And it decreases the expression of all forms of tau. It's akin to others have used an antisense approach to decrease the expression of tau, so it's a different mechanism of action. And we'll have to see -- the first thing is which one works the best. And then we'll see whether or not it can be done once and done or whether it will need to be regular infusions. Toby?

Toby Ferguson

Thank you, Al. I think what I would add is -- in concert, we fundamentally, at this point, don't have enough clinical data to understand the potential completeness of treatments with either with any of these modalities. I think first and foremost, the most important point is determining which ones work. and we're excited to test have 2 opportunities to test taus in our programs, both the antibody program and the knockdown program. I do think moving forward, we'll need to look and try to understand the combination as well, and that is the potential to be investigated in the future.

Alfred W. Sandrock

And Todd, do you want to take the second question?

Todd Carter

Sure. The second question, just to recap, would be the evaluation of ALPL and other in the context of other potential shovels or shovel targets for BBB delivery. So we absolutely would need to evaluate ALPL in the context of other receptors, such as transferin and there are a few others. While we're not in a position to share any data today, you can imagine that anything we would choose to move forward would need to perform at least as well as the existing BBB transporters and so that would be part of our assessment and our evaluation, and looking forward to, hopefully, in the future, being able to share more about our work in that area.

Alfred W. Sandrock

And then, Todd, I thought -- I think maybe David was also asking whether we have other receptors as well and how we're looking at those perhaps and comparing them to ALPL.

Todd Carter

So we have identified some other receptors. We have multiple capsid families that target different receptors. And so in terms of our novel receptor discovery, we have identified a few, and we are in the process of evaluating all of them for nonviral delivery.

Operator

Our next question comes from the line of Jay Olson of [Alco].

Unidentified Analyst

This is Chung on the line for Jay. Congrats on the progress. Maybe a 2-part question on the ALPL program you've disclosed. Just first, I'm just wondering if you can talk about the expression variability of ALPL in humans and maybe whether the expression may change over time with aging or with some underlying diseases. And secondly, for the development of other therapeutic modality or delivery modality using ALPL, are you planning to do that internally or through collaborations?

Alfred W. Sandrock

So Todd will answer the first question. I'll answer the second one.

Todd Carter

So on the first question, differences are changes of the ALPL expression. So we can look at different genetic variation of ALPL and we're in the process of doing that. In terms of the expression level, we know that ALPL is expressed at a quite robust level starting at birth from the databases and also from internal work on in preclinical models. That expression goes up a bit with age. So if anything, we might expect even better delivery in older populations, but all the evidence to date suggests that the level of expression in the vasculature is quite robust, even starting at a very early age.

Alfred W. Sandrock

Yes. And in terms of the second question, we do expect to be doing a lot of the work internally, and we have already started to do that. But we're always looking for collaborations that can enhance that discovery and development efforts. So stay tuned. SP1.

Operator

Our next question comes from the line of Sumant Kulkarni of Canaccord Genuity.

Sumant Satchidanand Kulkarni

Nice to see all the progress. I guess these are welcome questions for Dr. Toby Ferguson. So on your SOD1-ALS program, given the limited patient population and because tofersen is on the market already, do you expect to involve tofersen in preclinical work? And how do you expect eventual trial recruitment to play out for why SOD1-ALS program?

Toby Ferguson

Thanks for the question. So I think. Fundamentally, I think, so first one obviously is approved, and I think it's approved on the basis of a biomarker, particularly neurofilament, and it is indeed a disease-modifying therapy for ALS administered once interest. I think what I'd point to you on our programs...

Alfred W. Sandrock

Once a month.

Toby Ferguson

Excuse me, Once a month, excuse me. What I'd point you in our programs is that we did discuss recently at ASGCT really the transduction data. I think I'd highlight that at the start. In motor neurons, we saw 80%, 93% transduction and up to 6% to 8% in cortex when we looked at second-gen VCAP capsids. So that's really quite important. And that was with an intravenous administered dose. In the context of our VY-9323 program, we saw a 72% reduction of mRNA and SOD1 mRNA and 80% present in the core. So I think, fundamentally, we'll take some lessons learned from tofersen, particularly around the biomarkers.
We'll apply these to our clinical development program. We think this provides us an opportunity to understand not only the potential proof of concept in people with ALS, but also the potential importance for our TRACER platform as a whole.

Alfred W. Sandrock

And Sumant, maybe I'll add that if we look forward to the potential approval of our SOD1 gene therapy, I'll note that in the case of SMA, SPINRAZA was approved a couple of years prior to Zolgensma. And the 2 are used sort of in some ways concurrently in the real world. So for example, we're aware that many patients can get treated with Zolgensma right after birth. And then if necessary, they add SPINRAZA. And so taking a gene therapy doesn't preclude continued treatment with the person when necessary. And so I think if we take a page from the SMA story, we could see both products to person as well as, hopefully, our SOD1 gene therapy being used together essentially by physicians to treat their patients optimally.

Sumant Satchidanand Kulkarni

Got it. And as a quick follow-up, what percentage reduction on NFL is considered clinically relevant in the SOD1-ALS context? We've seen the data that Biogen had. But what would be considered clinically relevant, I guess, for what's out there already and for a gene therapy?

Toby Ferguson

So I think we've all seen the reductions that Biogen has highlighted with neurofilament reductions. I think, fundamentally, what a clinically relevant reduction is not clear. But I guess the points I would highlight is it has to be substantially greater than the variability of your assay and biologic variability and that the tofersen data does inform the magnitude of needs of reduction.

Operator

Our next question comes from the line of Yanan Zhu of Wells Fargo Securities.

Yanan Zhu

So first, I was wondering about the ALPL receptor, is there expression of this receptor on any other tissue? And how does that potentially impact or not impact a brain delivery drug in terms of delivery into other tissues?

Todd Carter

Sure. This is Todd. I can take that question. So thank you for it. So the ALPL is expressed across the vasculature and the entire body and in some other cell types. However, what we think is going on is that AAV capsids, AAV gene therapies do not need to harness these other mechanisms to get into other tissues. But the blood-brain barrier is blocking for most conventional capsids or all conventional capsids to get into the brain. So the harnessing of ALPL to cross the blood brain barrier is really only important to get into the brain.
What we also see is that the use of ALPL is giving us some significant cross-species activity. So it provides us not only with in-vitro evidence of cross-species activity in transcytosis assays, but also in vivo cross-species activity, which we see in multiple species.
So we have examples of 4 species: African green monkeys, cynomolgus macaques, marmosets and mice. And ultimately, what we're able to see is that at relatively low doses, we're able to achieve these kinds of high delivery in transduction that Toby mentioned. 80% of motor neurons in the spinal cord, 95% in Purkinje neurons and 98% of dopaminergic neurons in the substantia nigra.
And then finally, I'll just comment that with regard to the tissue and cell delivery, what we're seeing is a significant de-targeting from the liver. That's probably not specifically driven by ALPL or hypothesis is that's based on other characteristics of the capsid. But we see it quite substantially targeting human liver with the simultaneous increase in delivery into the CNS.

Yanan Zhu

Great. That's very nice to hear. And also at ASGCT, there are quite a few presentations on BBB penetrating capsid work from different industry players. And some of them also begin to touch upon receptors. I think you might have started a trend. Just wondering, after taking a survey of the landscape, how do you feel of your BBB capsid and where it stands in the landscape?

Alfred W. Sandrock

Maybe I'll start and Todd will complete the answer. But -- so listen, it's great to see that a lot of people are finding what we found years ago. And that -- yes, I mean, I think -- I think what we're seeing is that I think the world appreciates the need for new capsids that cross the blood-brain barrier, so as to improve delivery. And look, the competition is heating up. I would say that we're very proud of our capsids.
As Todd said, we get the key cells that are relevant for the diseases of interest. We get 80%, 90%, as Todd just mentioned, of cells transduced at relatively low doses of 3E13 VGs per kg, and we have demonstrated in vivo multiple cross-species experiments have been done with 3 different nonhuman primate species as well as mice, knowing the receptor is also very helpful. So -- and then look, we have already selected 3 development candidates, 2 with our partners at Neurocrine and 1 are wholly owned, and we expect to be in the clinic soon. So Todd?

Todd Carter

I think you captured everything that I was going to say, Al. And I do think the important point in addition to the cross-species activity is, over the past quarter or so, those 3 candidates that we're moving into the clinic. We think the next step is really the clinic.

Operator

Our next question comes from the line of Laura Chico of Wedbush.

Laura Kathryn Chico

Just one housekeeping question. I believe there was 1 milestone payment that was triggered in the second quarter. But curious if you could just kind of elaborate or if you've disclosed any additional milestones that we should be watching out for over the remainder of 2024? And then I have a quick follow-up for you.

Robin Swartz

This is Robin. Thank you for the question. So we were very pleased with the advancement of our Neurocrine programs. and the achievement of the DC milestone. However, we don't provide guidance on potential future milestone payments across the 13 partner programs. It is also important to note that further milestone payments are not included in our cash guidance, which is into 2027.

Laura Kathryn Chico

Okay. And then in terms of the follow-up, obviously, there's a lot of discussion on the ALPL receptor data from but I'm wondering if you can just talk, perhaps, Al, strategically, what would happen in terms of the direction of focus for Voyager with the VY-TAU01 data. If that reads out positively in the patients, what does that mean strategically in terms of the focus? Obviously, that's -- as an antibody right now, but how does that shift or change the focus on other TRACER programs, assuming success there?

Alfred W. Sandrock

Well, Laura, thanks for the question. I think what you're implying is that we would have a choice of whether we proceed with the VY-TAU01 program as an intravenous antibody or whether we could vectorize the antibody. We actually do have that option. We may actually do both, in fact. I've always been thinking, though, that strategically wouldn't make sense for a Voyager, a small company like us to try to go into Phase III or commercialize in Alzheimer's disease.
It's too large, too expensive. So we've always thought we will likely get a partner if the VY-TAU01 program is positive. But we -- but I do think that the option to potentially vectorize a once-and-done antibody could be of high interest to us, and we'll make that decision when the time comes.

Operator

Our next question comes from the line of Joon Lee of True Securities.

Joon So Lee

Following Laura's question, last week, in ASGCT, [BioPharm] suggested in some of the presentations that compared to capsid and inserted vectorized antibodies, the expression of -- sorry, capsid and inserted vectorized antibodies had a lower expression. Do you expect the same for your vectorized antibody platform in general and specifically for the Alzheimer's antibody. And if could you share any plans that you have for a preclinical data after in this program?

Alfred W. Sandrock

Yes. Let me start, and then I'll ask Todd to help. So the -- so when we vectorize an antibody, we did show at a meeting, I think it was last year or 2 years ago, that we can vectorize an anti-amyloid antibody and get enough expression to bind to amyloid plex in transgenic mice. And correct me if I'm wrong on that thought. So we can't get enough expression to bind to amyloid plaques in animals.
We'll have to see -- my view is that a lot is going to change relative to IV. So we're going to lose the Cmaxes, if you will, the high concentrations that you get immediately after IV dosing we expect to have more constitutive expression from within the central nervous system. So we expect that we'll have mainly glial cells producing the antibody.
As we've shown in the past and that we will -- and so it will be sort of an inside out, if you will, approach. Rather than giving an IV and having it across the vasculature to get into the brain, it will be made in the brain directly. And then we would be able to look in animal models at the. Not only binding to amyloid plex, but we will be assessing whether or not we can lower amyloid plex and there's some precedents we can follow in vivo studies that have been done with the anti-amyloid antibodies.
And then, of course, we'll have to see whether or not we affect any adverse events. One concept would be that ARIA the rates of ARIA may be affected by the fact that we don't get the Cmaxes, and we have constitutive expression from within the brain, we'll have to see if that's true. And there are some animal models that mimic ARIA, whether they truly are ARIA or not, well, I'm not certain, but we can even assess that.
And finally, I would say that one of the things we're investigating right now is whether or not we can regulate the expression of the antibody with a small molecule. And so a regulatable vectorized antibody program would, I think, be ideal. And so those are the kinds of things we're thinking about in terms of preclinical experiments. That would help us get to a development candidate.
Todd, did you want to add anything?

Todd Carter

I can add a little bit. So while the VY-TAU01, the focus there is on the antibody itself, not on a vectorized form. We do have substantial experience going back several years on factorization of antibodies in general, including tile antibodies and the amyloid that Al mentioned in others. And we found that the payload can matter quite a bit of the structure of the vector payload, the vector genome and of course, the promoter.
So there are a lot of things that we can do, some of which Al mentioned to tweak the expression level, not just on the promoter, but by the kinds of cells, the specific cell types that you target as well. And so we'll be looking at all of those characteristics when we move any vectorized form of an antibody -- gene therapy-based antibody forward.

Alfred W. Sandrock

I would just add that in the real world, being able to give a vectorized anti-amyloid once IV and not have to give it every other week or every month could really relieve the strain on the health care system that I think we're witnessing now with antibody treatments for Alzheimer's disease.

Joon So Lee

Very helpful. And if I can sneak in one last question. So between now and second half of 2026 that you hopefully represent like PET imaging data or VY-TAU01. How we should think about the cadence of any interim data release related to your findings along the way?

Alfred W. Sandrock

Toby?

Toby Ferguson

I think what we've highlighted for the SAD program, it will inform the MAD program. And I think really the key data readout in that time frame, really, in that data is the latter half of 2026.

Operator

Thank you. I'm showing no further questions at this time. I would now like to turn it back to Al Sandrock for closing remarks.

Alfred W. Sandrock

Thank you, everyone, for joining us today, and feel free to follow up directly with any questions. Thanks again. Bye.

Operator

Ladies and gentlemen, this concludes today's presentation. Thank you once again for your participation. You may now disconnect.