Solid Biosciences Inc. Q1 FY2021 earnings call

Opening Remarks

• Ilan Ganot provided an update on IGNITE DMD dosing, including two patients dosed, Patient 8's serious adverse event, and long-term biopsy data.

Clinical Update

• Cathryn Clary reviewed the clinical progress, working with the Data Safety Monitoring Board and steps taken with Patient 8's SAE.

Biopsy Data Presentation

• Carl Morris presented long-term biopsy data from the first three patients dosed at 2E14 vg/kg, showing sustained microdystrophin expression up to 24 months.

Preclinical Pipeline and Collaboration

• Joel Schneider shared updates on the preclinical pipeline, nomination of SGT-003 as the next development candidate, and the collaboration with Ultragenyx.

Financial Highlights

• Closed public offering in Q1 2021 with gross proceeds ~$143.8M, ending Q1 with $268.5M in cash and cash equivalents, which is expected to fund operating expenses into Q4 2022.

There are no distinct product segments with traditional revenue contribution as Solid Biosciences is focused on developing gene therapy for Duchenne muscular dystrophy. Financials noted include closing a public offering in Q1 2021 with gross proceeds of approximately $143.8 million before deducting expenses, ending the quarter with $268.5 million in cash and cash equivalents.

• On track to present 90-day biopsy data from Patients 7 and 8 in the second half of 2021.
• Cash and cash equivalents are expected to fund operating expenses through Q4 2022.

• Uncertainty in clinical development and regulatory processes.
• Impact of COVID-19 pandemic.
• Serious adverse event in Patient 8 during IGNITE DMD dosing, requiring investigation and evaluation.

Q: Everyone congrats on all the progress. My first question is on the longer-term expression data, which it’s encouraging to see those delayed kinetics and it seems like they correspond or correlate most closely to six minute walk in SEC clinical benefits as opposed to NSAA. So I was just wondering, how are you thinking about being able to take advantage of this observation, if you agree with that and try to establish whether these clinical end points or a composite of these with or without NSAA might improve the chances to get a microdystrophin gene therapy, such as SGT-001 or three across the goal line with the FDA.

A: Great question, Joe. Good to hear from you on, I think Carl will start and Cathryn will finish. Carl Morris: Yes, pretty good that you picked that up so quickly. Yes. There seems to be an apparent correlation, but it’s an out of three, and as, you can sort of make any associations you, like. I think by encouraged by the data overall there is variability, expected in these biological assays. We took different muscles from different – at different time points. So, but we are sort of quite sort of happy about it. It’s not unexpected or that we would see an increase in expression over time. But we need to get more data from all patients to really sort of start trying to look at specific relationships. I’ll turn it over to Cathryn to talk about the clinical trial and how we might be thinking, based on that. Cathryn Clary: Sure. Yes. Thanks a lot for the question. We were certainly very encouraged by these long-term results. And I think you asked the question which really gets to the heart of what we’re thinking about as a company, in terms of designing our registration trial. How do we, which outcome measures do we use? How can we find the most robust way to measure functional benefit in patients in such a heterogeneous disease? And as Carl said, this is a small data set so far, but we’re encouraged by it. We – it’s a bit early to start doing correlation analysis, although we’re certainly thinking about that and we look forward to getting the data on our two additional patients and others so that we can make those decisions.

Q: And as far as dosing, additional patients in the future, I was just wondering, what does that path look like for you from here? And could you characterize the SAE, which I heard you say was not unexpected, but had some complexity was this triggered by lab and or clinical findings? What can you tell us about the last patient to be treated with SGT-001?

A: Cathryn, you can keep going. Cathryn Clary: Sure. I’ll just keep going yes. So, as I said, the patient had an inflammatory response with elements similar to some of our other patients, which is why it was not unexpected, however the severity of the events was less severe than patient fix. We still are really looking at all the components of it from a casualty perspective. The patient course, we’re working both internally and with external experts to fully understand it so that we can move forward in a way that will ensure patient safety. You asked about the past dose in patients. We are working of course, with our DSMB, they reviewed the case, and we’ll be going back to them with the results of our investigation. And they will need to approve dosing the next patient, we already built in a minimum of 45 days between Patients 8 and 9. So, while we can’t speculate on exactly when we’ll dose Patient 9, and then already there was going to be a bit of a delay, and then we’re working with FDA as well.

Q: Thank you for taking my questions. I have three questions. The first one was to regarding the Patient 8 inflammatory response. Just wondering, any additional color you can give regarding this patient. You did present at the ASGCT, showing the zero positive AAV9 is related to complement activation. And I think of Pfizer also, shared some additional color on their safety understanding of the safety. So, if you can give a little bit more color on this patient and what exactly that inflammatory response was and what kind of baseline characteristics from this patient with zero positive also, the platelet count [ph], any other information you can give? That’s the first question. My second question is regarding the SLB101. Did you test in non-human primates? What is the safety look like in non-human primates and also, which backbone was for – was derived for SLB101. My last question is more the future direction, you do have your own internal SGT-003, but you also a real collaboration, how do you prioritize? Do you see this as an internal competition?

A: Awesome questions, Gena. I think we’re going to start with Cathryn to talk a little bit about the SAE and then she can hand it over to Carl to finish that off and then talk about SLB101. And I’ll talk about the priorities at the end. Cathryn Clary: Thank you, Gena for the question. So as, I mentioned, patient aid did have an inflammatory response with elements that were similar to what we had seen in some of the other patients you asked about compliment activation. It’s an interesting compliment activation is part of the innate immune response, and we’ve actually seen laboratory evidence of compliment activation in all eight of our treated patients. Patient 7 had as we reported before, had some compliment activation in lab but did not, it was lower than what we had seen in some other patients. We’re still really evaluating the elements of Patient 8. Every patient appears to be somewhat different and we haven’t really identified a common factor with our SAEs, but we’re still examining certain elements of it. And we will, once we see the results of that investigation are done, we can provide some additional information. Carl Morris: And hi, this is Carl. So, yes, and the ASGCT place there has been is highlighting that’s in the presence of antibodies AAV and it doesn’t matter if it’s AAV9 or AAV8, we will share both can activate the complement system. So, we think this is an effect that will be seen, through, within different programs. So, I think we’re getting a better handle on it. And other companies are seeing that as well. Regarding SLB101 and SGT-003 the capsid is derived from some rational design that we did internally. So rather than going through a computational analysis, like a number of companies we sort of went from the other way and looked at using our muscle expertise to, I think about how best to target muscles specifically. And we identified a number of capsids that look promising. It’s very early on in the plan. And we’re still in sort of lead optimization right now. So, we haven’t sort of finalized that the candidate, but we planted it to be moving into IND-enabling studies as soon as possible. Once we’ve identified, there’s a specific capsid and specific transgene as well that we’re using. So, I’ll pass it back to Ilan.

Q: Hi, thanks so much for taking our question. This is Sonia on for Salveen. So, I know you’re currently evaluating what caused the information in Patient 8? Do you happen to have any initial hypothesis on why that might’ve happened? And then our second question was just when are we going to see any additional functional data from Patients 7 and 8? Thank you.

A: Hey, thank you, Sonia. Cathryn? Cathryn Clary: So thanks very much for the question. So we really, I don’t want to speculate right now on causality because we are looking at several things. As we reported, our principal investigator did deem the event to be drug related. And it does have some elements that are similar to our other patients that less severe than we saw in Patient 6 and Patient 7 of course dosed under our new protocol had a very safe dosing. So, we’re evaluating a number of different factors. And as I said before, we’ll definitely get back to you when we have a better handle on exactly what happened and what some of the causes were. In terms of the functional data, Patient 7 is approaching a 90 day visit. It’ll be a while. We don’t really look at functional data at 90 days or reported because of the steroids still ingrained in the system. So, there’ll be a while before there’ll be additional functional data. And we haven’t actually guided to that.

Q: Hi guys. Thanks so much for taking the question. Just a clarification question here, has the patient SAE and sort of clinical profile of this patient being shared with FDA and the DSMB, and what are the timelines for feedback from both of those groups?

A: Hi, Anupam. Absolutely, we shared with the FDA and with the DSMB and we have ongoing dialogues. We are not really able to project timelines, but have been shared and discussed.