Enanta Pharmaceuticals, Inc. Q1 FY2024 earnings call

RSV Program

• RSV is a severe respiratory infection with low vaccine and prophylaxis uptake. Enanta's zelicapavir (N-protein inhibitor) and EDP-323 (L-protein inhibitor) have fast-track designation. Zelicapavir is in Phase 2 studies (RSVPEDs in pediatric RSV patients and RSVHR in high-risk adult RSV patients). EDP-323 is in a Phase 2a challenge study. Anticipate reporting RSVPEDs data in Q3 2024 and EDP-323 data in Q3 2024.

Immunology Program

• Focus on chronic spontaneous urticaria (CSU) with goal to develop a best-in-disease oral KIT inhibitor. Prototype inhibitor has favorable properties. Plan to announce development candidate for CSU this year and pursue additional immunology programs, with a second program to be announced in 2024. Emphasize high unmet need in CSU and potential for KIT inhibitor in other allergic diseases.

In the fiscal first quarter ended December 31, 2023, total revenue was $18 million, consisting of royalty revenue from AbbVie's MAVYRET. Research and development expenses were $36.4 million, down from $40.9 million in the prior year primarily due to a decrease in COVID-19 program costs. General and administrative expense was $16.5 million, up from $12.7 million in the prior year due to increased stock compensation and legal expenses. Net loss was $33.4 million, or $1.58 per diluted common share, compared to a net loss of $29 million, or $1.39 per diluted common share in the corresponding period of 2022. Enanta ended the quarter with approximately $337 million in cash and marketable securities.

Forward-Looking Guidance

• Anticipate reporting results from EDP-323 Phase 2a challenge study in Q3 2024.
• Anticipate reporting RSVPEDs Phase 2 study data in Q3 2024.
• Plan to identify a clinical candidate for CSU program in 2024.
• Plan to announce a second immunology program in 2024.
• Current cash position sufficient to meet anticipated cash requirements through fiscal 2027.

Risks

• Forward-looking statements involve assumptions and risks beyond control, detailed in Enanta's most recent Form 10-K and other periodic reports filed with the SEC. Enanta does not undertake to update forward-looking statements.

Q: Hi, thanks for taking the questions. I just had a few on zelicapavir. First one on the RSVPEDs readout, presumably in 3Q. I guess under the negative scenario where you don't see any virological effects, is it conceivable that you just wind down the program, stop RSVHR, or would you still see RSVHR readout? And then in that same scenario, and if the challenge file for 323 is highly positive, would you potentially look to immediately combine the two agents?

A: Thanks, Roy. This is Jay. So starting with the challenge study, 323 is also on track for Q3. It's a very potent L-inhibitors. As you know, I know you know a lot about the data. And given the potency, given the PK, given the huge multiples we drive over the protein-adjusted EC90, we're very hopeful that it should show, efficacy, comparable to zelicapavir. The question of getting into combination studies right away is an interesting one. But I think, we'll probably be most interested in fully characterizing single-agent efficacy for both zelicapavir and 323 in real world and then contemplate combinations. Of course, in parallel, you could be scouting out, some of the combinations in challenge studies, foreshadowing that. But I think we wouldn't want to slow down single-agent characterization of 323. The PEDs study, again, we're on track for Q3. You're asking an interesting question. If PEDs didn't show anything, what would you do with HR? Different patient populations, I think you've got to look at the facts and circumstances, around any clinical trial result in one patient population, done under one set of conditions. And then, make good judgments as to how it might, or might not relate to a different clinical trial in a different patient population, under a different set of circumstances. So, we just need to look at data. So that's my thought on that.

Q: Afternoon, everyone. So a question on your CSU program. So could you walk us through some of the elements that excited you about, this indication over other similar immunology indications? And I was curious what additional optimization might you, try to be working on, to get to a final candidate that could be deemed, like best in disease?

A: Okay. Well, I'll handle part of that question, and then I'll let Tara Kieffer, Heads our Product Strategy, talk about the other part. So with regards to the optimization, I think we showed some data at JPMorgan on a prototype molecule, which we think is far along in terms of our optimization profile. We're still making lots and lots of molecules, continuing to tweak bits and pieces. But obviously, among the things we're looking at, is just really honing down potency, selectivity, making sure we've got good safety. And of course, our old friend pharmacokinetics, and hopefully once daily dosing, all of those kinds of things that we like to build in to every one of our molecules. CSU is attractive, and maybe I'm already answering some of the questions, but we're not certainly limiting ourselves to that. I think it happened to be the first program that we've announced in the area. But we're working on a few other things. We're piloting other programs, getting involved. So you can expect that there will be a broader footprint, certainly, as our slide deck anticipates in the field. And we go about it in the way that, we've done in a lot of our, well, in pretty much all of our programs. We get the biology figured out and sorted, really important to do that. Try to figure out chemical matter that, we can get into. Make sure we've got strong commercial rationale in terms of competitive landscape, potential product profiles, we set all that stuff. Start making molecules, get on the boards, start filing intellectual property. And we tend to do all of that, before we really announce a program. So suffice it to say, that's ongoing in other areas, and as the year rolls out, we'll come out with more. Does that answer your question?

Q: It doesn't seem like the Phase 2b RSVPEDs study is powered to hit on symptoms or viral load reduction. So what would be a strong enough signal for you to move it into Phase 3? And then additionally, how are you thinking about the oral from death severe failure for Gilead? Does that change strategic value for your protease inhibitor at all?

A: Yes, I can build on - for the RSVPEDs piece. Yes, we will again, primarily be looking at virology. And I think there's not a lot of benchmarks in this area that, we could point to, or compare to. There is one data set out of a company called [ArcBio] where in a Phase 3 trial, they showed about a 0.6 log drop. And that did translate into an improvement, specifically significant improvement on symptoms. So that is the one sort of benchmark that we have. But again, numerical trends and directional data showing that zelicapavir is showing an improved trend in virology, compared to placebo, would give us the confidence to move forward into a Phase 3 study. Again, we'll look at symptoms. And as you said, it is a small study and the likelihood of seeing something on that, certainly in a statistically significant way is probably not as high, but we'll look at that and see what we get. Okay. And the second part, I guess, is relates to oral remdesivir for COVID. I mean, I guess our initial reaction, I mean, we, like everybody else, just got that news late yesterday afternoon. I think it simplifies the COVID landscape, which is - one of the things that I think everybody who's involved in COVID, including us, everybody who's interested in COVID, whether its strategics or the government. We're trying to figure out what the competitive landscape is, or what the arsenal of drugs is going to be available for COVID patients. And it seems like there's one fewer now. So that's going to help clarify things. I guess, Chianogi is another one that's due to turn over a card pretty soon here. I guess there's a question about what's Pfizer doing with their follow-on molecule. We haven't seen that they've advanced it, but so a question mark there that will hopefully get sorted here in the nearer term. And then, we'll have a more complete view of what that competitive landscape looks like, which is, again, important for anybody who would be making funding decisions going forward. Our plan, as we've stated a few times before, is to only pursue 235 in the context of a collaboration.