Alnylam Pharmaceuticals Inc

NASDAQ:ALNY

Earnings Call Analysis

Alnylam Posts Strong Q3 Growth, Forecasts Higher Revenues

In Q3 2023, Alnylam Pharmaceuticals reported a notable 35% increase in product revenues to $313 million, supported by its TTR and Ultra-Rare franchises. A collaboration with Roche and a milestone from Regeneron helped the company achieve its first non-GAAP operating profit of $278 million for the quarter. Notably, the company has upped forecasted collaboration and royalty revenues to $575-625 million due to these partnerships. Despite an anticipated reversion to non-GAAP operating loss in future quarters, a cash balance of $2.4 billion is expected to secure financial sustainability.

Encouraging Product Performance and Revenue Uplift

Starting off on a positive note, the company has seen a robust 19% increase in product sales for OXLUMO compared to the previous quarter, signaling a healthy demand trajectory. This surge in sales is attributed to a 10% increase in the U.S. market—thanks to a strong 16% growth in demand—and an even more impressive 23% rise internationally, fueled by both heightened demand and the timing of orders in emerging and partner markets. Additionally, the company's TTR and Ultra-Rare franchises marked an 8% upswing in patient therapy numbers and a striking year-over-year revenue growth over 30%. Looking forward, the company strategically anticipates ending the year around the midpoint of its net product revenue guidance range.

Developments in TTR Franchise

Turning to the TTR franchise, the company has two FDA-approved products addressing hereditary ATR amyloidosis: ONPATTRO and AMVUTTRA. Despite a setback with the FDA declining approval for ONPATTRO's expansion to ATTR cardiomyopathy, due to doubts about the clinical meaningfulness of the data, the company has decided not to invest further in this direction. Instead, all eyes are on the upcoming HELIOS-B study outcomes, expected in early 2024, which could potentially secure an expanded label for AMVUTTRA. The company remains confident, strengthened by the positive data from the APOLLO-B study that showed stabilization of patient conditions over a two-year period—a hopeful sign in an otherwise progressively worsening disease.

Pipeline Progress and Partnerships

The company's innovation pipeline continues to generate excitement, particularly with its Phase 1 Alzheimer's study demonstrating promising interim results. With ALN-APP's novel treatment leading to substantial and sustained reductions in Alzheimer's biomarkers and a pending multiple dose part of the Phase 1 study, there is considerable anticipation for future updates. Additionally, positive Phase 2 results for zilebesiran in treating hypertension were revealed, and the company is eager to share more details at the forthcoming AHA Scientific sessions. In another bright spot, Sanofi's Phase 3 study for their partnered program is progressing well, with plans to file a New Drug Application (NDA) in 2024.

Financial Strength and Guidance

Financially, the third quarter of 2023 was robust with a 35% increase in total product revenues compared to the previous year, boasting $313 million in earnings. This growth was significantly spurred on by the strong performance of both the TTR and Ultra-Rare franchises. Collaborative efforts have proven lucrative, with net collaboration revenues rocketing to $427 million, largely thanks to the zilebesiran collaboration with Roche and a major milestone achievement with Regeneron. Despite a disappointing 10% decrease in gross margin, primarily due to ONPATTRO inventory write-offs, the company's non-GAAP operating profit reached $278 million for the quarter. Looking ahead, the collaboration and royalty revenue guidance for the year has been significantly increased to the range of $575 million to $625 million, reflecting the recognition of major payments within key partnerships.

Operational Efficiency and Expansion Efforts

The company is pushing forward with global commercialization endeavors for its suite of products including ONPATTRO, AMVUTTRA, GIVLAARI, and OXLUMO. At the same time, it is progressing in early clinical development for neuroscience with its ALN-APP program. With these strategic moves, the company is shaping a promising horizon, which could translate into foreseeable profitability and advancement within its ATTR franchise.

Earnings Call Transcript 2023-Q3

[Operator]

Good day, and thank you for standing by. Welcome to the Alnylam Pharmaceuticals Q3 2023 Earnings Conference Call. After the speaker's presentation, there will be a question-and-answer session. Please be advised that today's conference is being recorded. I would now like to hand the conference call over to the company.

[Christine Lindenboom, executive]

Good morning. I'm Christine Lindenboom, Senior Vice President of Investor Relations and Corporate Communications at Alnylam. With me today are Yvonne Greenstreet, Chief Executive Officer; Tolga Tanguler, Chief Commercial Officer; Pushkal Garg, Chief Medical Officer; and Jeffrey Poulton, Chief Financial Officer. For those of you participating via conference call, the accompanying slides can be accessed by going to the Events section of the Investors page of our website investors.alnylam.com/events.

During today's call is outlined on Slide 2, Yvonne will offer introductory remarks and 5 general context. Tolga will provide an update on our global commercial progress. Pushkal will review pipeline updates and clinical progress, and Jeff will review our financials and guidance, followed by a summary of upcoming milestones before we open the call to your questions. I'd like to remind you that today's call will contain remarks concerning Alnylam's future expectations, plans and prospects, which constitute forward-looking statements for the purposes of the safe harbor provision under the Private Securities Litigation Reform Act of 1995.

Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including those discussed in our most recent periodic report on file with the SEC. In addition, any forward-looking statements represent our views only of the date of this recording and should not be relied upon as representing our views as of any subsequent date. We specifically disclaim any obligation to update such statements.

With that, I'd like to turn the call over to Yvonne. Yvonne?

[Yvonne Greenstreet, executive]

Thanks, Christine, and thank you, everyone, for joining the call today. In the third quarter of 2023, we continue to make great progress across our business while also experiencing a disappointment. As we announced last months, the U.S. Food and Drug Administration, the clients improved the supplemental new drug application for patisiran an investigational RNAi therapeutic that was in development for the treatment of the cardiomyopathy of ATTR amyloidosis.

As we have conveyed, we are extremely disappointed with this outcome, particularly with regard to the needs of patients, many of whom spoke at the Advisory Committee meeting in September. We have been steadfastly committed to this under [indiscernible] for over [ 3 ] decades and remain confident in our long-term strategy to building a leading TTR franchise with vutrisiran and the HELIOS-B study serving as a very important next step in this journey. We look forward to sharing those top line results, which remain on track for early 2024. As we continue to progress our plans in ATTR cardiomyopathy, our commercial strength in the third quarter was driven by the ongoing successful launch of AMVUTTRA in patients with hereditary ATTR amyloidosis with polyneuropathy.

This contributed to a 35% year-over-year growth in total net product revenues compared to the third quarter of 2022. We also delivered important clinical updates from key pipeline programs in the third quarter. In September, we announced positive top line results in the KARDIA-1 Phase II dose-ranging study of zilebesiran, which demonstrated greater than 15 millimeters of mercury reduction of systolic blood pressure at 3 months of treatment compared to placebo as what is an encouraging safety and tolerability profile in adult patients with mild to moderate hypertension. Additionally, the results also reflected sustained reductions of the solid blood pressure at 6 months, supporting the potential for quarterly or biannual dosing.

We also shared updated positive interim results from the Phase I study of ALN-APP in patients with early onset Alzheimer's disease, which showed rapid and robust target engagement with sustained effects out to 10 months with a single dose and an encouraging clinical safety and tolerability profile. Additionally, we presented data from the APOLLO-B study of patisiran at HFSA, showing that the effects of patisiran treatment on 6-minute walk test and KCCQ were maintained through 24 months of treatment. This type of relative stabilization in what is otherwise a steadily progressive disease is very encouraging and further bolsters our confidence in [ APP ].

We're thrilled to have had these results published in the New England Journal of Medicine just a few weeks ago, which is accompanied by a favorable editorial highlighting the step forward represented by RNAi therapeutics in this disease. Lastly, we're excited to have achieved the third place ranking in Science Magazine's top employer survey for 2023. This marks the fifth year that Alnylam was featured as one of the top 3 companies in their annual survey of industry professionals. We are poised to deliver a couple more pipeline updates by the end of the year, including top line Phase I results for ALN-TTRsc04 as well as ALN-KHK, our investigational RNAi therapeutics for type 2 diabetes.

And I encourage you all to save the date and tune into our annual R&D Day, which will be held virtually on December 13, where we will discuss all of the exciting progress across our pipeline and platform. We believe all of this puts us on track with our Alnylam [indiscernible] by 25 goals, making Alnylam a the top-tier biotech developing and commercializing transformative messages of patients around the world with rare diseases and beyond, driven by a high-yielding pipeline of first and/or best-in-class product candidates from our organic product engine, all while delivering exceptional financial results.

With that, let me now turn the call over to Tolga for a review of our commercial performance. Tolga?

[Tolga Tanguler, executive]

Thanks, Yvonne, and good morning, everyone. Q3 was another strong quarter for our commercial portfolio with both our TTR franchise, driven by another robust quarter of our mature performance in the U.S. market and our Ultra air franchise delivering growth in excess of 30% compared with the prior year as we continue to steadily increase the number of patients on all of our therapies.

Total net product revenues grew 35% year-over-year for the third quarter or 33% at a constant exchange rate. Let me now turn to a summary of our third quarter TTR performance. Our TTR franchise achieved $230 million in global net product revenues for ONPATTRO and AMVUTTRA, representing a 3% increase compared with the second quarter and 35% growth compared with the third quarter of 2022. At the end of the third quarter, more than 3,790 patients were on commercial ONPATTRO or our mutual treatment worldwide, up from over 3,490 patients at the end of the second quarter, representing 8% quarterly patient growth.

Now let me provide highlights of our U.S. and international TTR performance. In the U.S., combined sales of ONPATTRO and AMVUTTRA increased by 11% compared with the second quarter, and a robust 47% year-over-year driven by [ our third ] launch. The U.S. growth was primarily driven by the following: a 6% increase in demand which was driven by the strength of ongoing AMVUTTRA patient uptake, more than offsetting a decrease in ONPATTRO patients that switched AMVUTTRA. At the end of the third quarter, more than 80% of Alnylam U.S. TTR patients are now on AMVUTTRA at positive time indicating how well the product profile has been received by both prescribing physicians and patients.

In addition to the demand growth, reported growth was also favorably impacted by approximately 5% due to an increase in our [ motor ] inventory in the distribution channel. Now let me turn to our international markets, where TTR franchise growth decreased by 7% compared with the second quarter. Although there was growth in patients on therapy during the quarter, this growth was offset by a variety of factors, including price adjustments in Germany following the end of the 6-month prepricing period, inventory destocking in Japan and the timing of orders in emerging and partner markets. It is worth noting that we have now launched AMVUTTRA in all major international markets following recent launches in Spain and Italy. I'm proud of the efforts of our market access team as we have made on which are available to patients, and secured reimbursement significantly faster than industry benchmarks.

Now moving to our ultra-rare products and the performance of GIVLAARI and OXLUMO, which delivered $83 million in combined product sales during the third quarter, representing a 1% increase compared with the second quarter and a solid 33% growth compared with the third quarter of 2022. We ended the quarter with more than 1,000 patients on our 2 Ultra-Rare products, an exciting milestone with more than 625 patients on GIVLAARI commercial therapy, and more than 375 patients on OXLUMO commercial therapy, representing 8% combined quarterly growth in patients on our Ultra-Rare products compared with the second quarter 2023. For GIVLAARI, product sales declined 6% in Q3 compared with the second quarter, with the following regional dynamics.

A 5% increase in demand in the U.S. market, driven by an increase in patients on therapy, a 25% decrease in our international market, driven by the timing of orders in emerging and partner markets, where as we previously indicated, Q2 results benefited from a large order and higher gross to net reduction. For OXLUMO, we delivered a robust 19% increase in product sales compared with the second quarter, which was driven by the following: a 10% increase in the U.S. driven by 16% demand growth, partially offset by a reduction of inventory in the distribution channel, a 23% increase in our international markets, driven by increased demand and the timing of orders in our emerging and partner markets.

We were pleased with the results in the quarter, particularly the strong patient growth with both our TT and Ultra-Rare franchises, delivering an 8% increase in patients on therapy during the quarter as well as delivering robust year-over-year growth in revenues with both franchises growing in excess of 30%. As we look ahead to the end of the year, we anticipate a strong fourth quarter, positioning us to end the year at the approximate midpoint of our net product revenue guidance range.

With that, I will now turn it over to Pushkal to review our recent R&D and pipeline progress. Pushkal?

[Pushkal Garg, executive]

Thanks, Tolga, and good morning, everyone. Let me start with our TTR franchise. As you know, we have 2 products approved for the polyneuropathy of hereditary ATTR amyloidosis. ONPATTRO and AMVUTTRA. We've also been pursuing expansion into ATTR cardiomyopathy through 2 large studies, APOLLO-B for patisiran and HELIOS-B for vutrisiran. As previously announced, while APOLLO-B delivered positive results, not just on the primary endpoint, but consistently across additional secondary and exploratory endpoints as well, all with a positive safety profile. The FDA declined to approve the sNDA for patisiran, citing insufficient evidence of clinical meaningful.

As a result of this decision and with the top line readout from HELIOS-B expected in early 2024, we have elected not to invest further into additional development to secure approval for patisiran in ATTR cardiomyopathy in the United States. The positive data on multiple aspects of ATTR cardiomyopathy coming out of the APOLLO-B study reaffirm our confidence in the success of HELIOS-B. In particular, the 24-month data show that both 6-minute walk test and KCCQ were relatively stable over the entire period in contrast with large expected declines expected in this disease, and suggest the potential that RNAi-mediated TTR silencing may result in a differentiated efficacy profile in this disease.

The HELIOS-B study is designed and powered to demonstrate a benefit of vutrisiran in patients very similar to those studies in APOLLO-B on the composite outcome of all-cause mortality and recurrent cardiovascular events over a 30- to 36-month period. The study is on track to read out in early 2024. And assuming positive data, we then plan to seek a label expansion for AMVUTTRA and if approved, ultimately launched that medicine into the growing market of patients around the world with wild-type or hereditary ATTR amyloidosis with cardiomyopathy. We believe that the convenient quarterly subcutaneous dosing regimen with a therapeutic profile that includes cardiovascular outcomes dated in its label could potentially position AMVUTTRA as a transformative therapy with a market-leading profile for patients with this disease.

Moving on, following the announcement of initial human proof-of-concept data on ALN-APP, our first RNAi therapeutic design for CNS delivery, which is in development for the treatment of Alzheimer's disease and cerebral amyloid angiopathy, we are excited by the positive results we've seen from the Phase I study to date. As the clinical trials on Alzheimer's disease conference a few weeks ago, we presented additional positive interim results from the Phase I study in patients with early onset Alzheimer's disease. At the time of this interim look, 20 patients have been enrolled in 3 single dose cohorts in Part A of the ongoing Phase I study.

To date, we've studied 3 dose levels, 25, 50 and 75 milligrams with 4 to 6 patients dosed in each cohort. Excitingly, ALN-APP treatment resulted in rapid, dose-dependent and sustained reductions in both soluble APP alpha and beta, biomarkers of target engagement in the CSF. We saw rapid knockdown as early as day 15 and observed peak mean reduction of 69% and 82%, respectively, for soluble APP alpha and soluble APP beta. Reduction was sustained with a mean reduction of 33% and 39%, respectively, for soluble APP alpha and beta 10 months after a single 75-milligram dose.

We also presented clinical data that for the first time, showed marked reductions in A beta 42 and A beta 40, the soluble forms of the amyloidogenic peptide that aggregate into amyloid deposits in Alzheimer's disease and CAA. Specifically, at 2 months after a single dose of 75 milligrams of ALN-APP mean reductions of CSF AB42 and AB40, were 49% and 71%, respectively. Given that these peptides are directly implicated in disease pathogenesis, these findings are encouraging as they suggest that treatment with an RNAi therapeutic can potentially interrupt relentless progression of these 2 devastating diseases.

The safety of single doses of ALN-APP has been encouraging as well. All adverse events were mild or moderate in severity and CSF parameters have not revealed any significant abnormalities to date. Further exploration of single doses of ALN-APP is ongoing in Part A. In addition, Part B, the multiple dose part of the study has been initiated in Canada and has now also received all required approvals to proceed in the United Kingdom and the Netherlands. Multiple dose part of the study remains on partial clinical hold in the United States due to findings observed in prior nonclinical chronic toxicology studies. In sum, I'm thrilled about these impressive human data showing the potential for RNAi to sounds disease-causing transcripts in the CNS and look forward to providing additional program updates in the future.

Let me now turn to recent progress with zilebesiran in development for the treatment of hypertension. We are very excited to have reported positive top line results from the KARDIA-1 Phase II dose-ranging study. In KARDIA-1, zilebesiran met the primary endpoint, demonstrating a dose-dependent, clinically significant reduction in 24-hour mean systolic blood pressure measured by ambulatory blood pressure monitoring at month 3, achieving a placebo subtracted reduction greater than 15 millimeters of mercury with both 300 milligrams and 600-milligram doses. The study also met key secondary endpoints, including significant change and 24-hour mean systolic blood pressure as measured by ABPM at month 6 as well as significant change in office systolic food pressure at months 3 and 6 for all zilebesiran arms compared to placebo.

The study results indicate [indiscernible] was associated with dose-dependent potent and durable knockdown of serum AGT levels through month 6. Importantly, zilebesiran demonstrated an encouraging safety and tolerability profile. We look forward to sharing complete results for KARDIA-1 at the upcoming AHA scientific sessions this month, and we remain on track to deliver top line results from the KARDIA-2 Phase II combination study of [ zilebesiran ] in early 2024. Before I wrap up, I'd like to briefly update on one of our partnered programs, [ vutrisiran ], which is in development for the treatment of hemophilia A or B with or without inhibitors.

Sanofi just reported encouraging safety and efficacy data for the antithrombin-based dosing regimen in a Phase III study, and indicated they are currently in discussions with the FDA regarding filing an NDA in 2024. These are just a few highlights from a broad and innovative pipeline driven by our underlying organic product engine that we expect will deliver sustainable innovation and represents a key growth driver for Alnylam in the years to come. With that, let me now turn it over to Jeff to review our financial results and upcoming milestones. Jeff?

[Jeffrey Poulton, executive]

Thanks, Pushkal, and good morning, everyone. I'm pleased to be presenting a summary of Alnylam's Q3 2023 financial results and discussing our full year guidance. Starting with a summary of our P&L results for Q3 2023. Total product revenues for the quarter were $313 million or 35% growth versus Q3 2022. As Tolga previously mentioned, the increase was driven by strong growth from our TTR and ultra-rare franchises with both reporting growth greater than 30% during the quarter compared with the prior year.

Our reported results in the quarter benefited modestly from foreign exchange as constant exchange rate product sales growth was 2% lower at 33%. Net revenue from collaborations for the third quarter was $427 million, representing nearly a $400 million increase from Q3 2022 primarily due to increases in revenue from our zilebesiran, co-development and co-commercialization collaboration growth, which included full recognition of the $310 million upfront payment received in the third quarter as well as $65 million in revenue in connection with our Regeneron collaboration. The $65 million represents the portion of revenue recognized from a $100 million milestone earned from achieving certain criteria during early clinical development for our CNS program, ALN-APP.

Royalty revenue during the quarter was $10 million, which was driven by Novartis sales of Leqvio, which continued to increase following launch in the U.S. in the first quarter of 2022. Gross margin on product sales was 75% in Q3, representing a 10% decrease compared with the third quarter of 2022, primarily due to a Q3 write-off of ONPATTRO inventory that have been manufactured for future demand associated with the ATTR cardiomyopathy indication for patisiran for which we did not receive regulatory approval. Recall that I mentioned on our ONPATTRO CRL investor call on October 9 that we expect ONPATTRO demand to decrease on a go-forward basis as AMVUTTRA continues to cannibalize existing ONPATTRO polyneuropathy business in markets where Ambutra has launched.

As a result, for 2024, we anticipate ONPATTRO product sales will be in the $200 million to $225 million range. A non-GAAP R&D expenses increased 16% in the third quarter compared to the same period in 2022, primarily due to higher costs related to clinical activities and increased head count to support our R&D pipeline and an expense for achievement of certain milestones payable to a partner. Our non-GAAP SG&A expenses increased 2% in the third quarter compared to the same period in 2022, primarily due to increased head count and other investments supporting our strategic growth, including the global launch of AMVUTTRA. For the first time in Q3, we generated non-GAAP operating profit during the quarter, equal to $278 million driven by the significant revenue recognized during the quarter from our collaborations with Roche and Regeneron.

We anticipate that in future quarters, we will revert to a non-GAAP operating loss as we have not yet achieved sustainable profitability. Finally, we ended the quarter with cash, cash equivalents and marketable securities of $2.4 billion compared to $2.2 billion at the end of 2022 with the increase primarily related to the $310 million upfront payment from Roche offset by our operating loss year-to-date. We continue to believe our current cash balance is sufficient to bridge us to a self-sustainable financial profile. Now I'd like to turn to our full year 2023 financial guidance.

We are increasing our collaboration and royalty revenue guidance from $100 million to $175 million to $575 million to $625 million. The substantial increase is primarily attributable to 2 factors that were not included in our previous guidance. First, recognition of the full $310 million upfront payment received from Roche in the third quarter in conjunction with zilebesiran collaboration. I would also like to note that our accounting conclusions associated with the Roche collaboration are summarized on Slide 27 in the appendix of today's presentation. And secondly, achievement of the $100 million ALN-APP milestone from Regeneron during the third quarter, the majority of which will be recognized as revenue during 2023. All other elements of our 2023 financial guidance remain unchanged.

Let me now turn from financials and discuss some key goals in our upcoming milestones slated for the remainder of 2023. We will, of course, be executing on global commercialization of our products, ONPATTRO, AMVUTTRA, GIVLAARI and OXLUMO. We intend to report top line results from Phase I studies of ALN-TTRsc04 in development for the treatment of ATTR amyloidosis and ALN-KHK, in development for the treatment of type 2 diabetes. With our partnered programs, we are expect to report further results from Phase II combination trials of ALN-HBV02 in development for the treatment of chronic hepatitis B. Let me now turn it back to Christine to coordinate our Q&A session. Christine?

[Christine Lindenboom, executive]

Thank you, Jeff. Operator, we will now open the call for your questions To those elements, we would like to ask you to limit yourself to 1 question each and then get back in the queue if you have additional questions. .

[Operator]

Thank you. At this time, we will conduct the question-and-answer session. [Operator Instructions] Our first question comes from Ritu Baral of TD Cowen.

[Ritu Baral, analyst]

I wanted to ask a little bit about the HELIOS-B statistical -- sorry, the statistical plan. I understand that you're using the Andersen-Gill method, in which our statistical consultants anyway said that any kind of CD event would be analyzed as a recurring event and would count, and versus what has been used by other developers where they had ranks of -- they had to rank events. Within this Andersen-Gill are event of different types in the composite weighted equally? Or are certain events like death and hospitalization weighted more such that the analysis may be more meaningful to doctors for serious events and regulators as well?

[Yvonne Greenstreet, executive]

Thanks, Ritu. Kind of a great question. I mean as you know, we're laser focused on delivering a successful HELIOS-B study and feel confident just given our track record in there and all the studies that we've delivered that have been positive to date. But in regards to your specific question around how we're thinking about the statistical analysis, Pushkal, maybe you could provide a few perspectives.

[Pushkal Garg, executive]

Yes. Thanks, Ritu. Look, I think there's lots of ways that people look at these types of data. As you mentioned, our focus is really on definite recurrent hospitalizations, and both -- I think [indiscernible] felt and then Andersen-Gill can do that. I think one of the unique aspects of the study that we've done to sort of increase and maximize power is actually have differential follow-up for patients. So we have a follow-up that can range from 30 to 36 months. And the Andersen-Gill allows us to actually incorporate that variable follow-up, whereas in the single seen shown fell that follow has to sort of be aligned to the lowest common denominator. So it actually gives us some additional power.

And that's why our statisticians and our team is -- we've prioritized that in the statistical analysis plan. So certainly, it means depth, but we look at all of those depth in the hospitalization events as those recurrent events that you talked about. So we think that really optimizes the power for the study.

[Operator]

Paul Matteis of Stifel, your line is now open.

[Paul Matteis, analyst]

Great. I appreciate it. We've been trying to think about what, if any, learnings there are from the recent advisory committee to HELIOS-B. And we fully understand, right, that HELIOS-B is generating outcomes data, the issues with APOLLO-B at the FDA level are related to a lack of that to some extent. That said, I was curious if you think from a regulatory perspective, it's important that you show some level of added outcomes benefit on top of tafamidis. And I'm assuming the study is not really powered for a p-value but how would you kind of delineate what the line is on a clinically meaningful effect in the combo therapy subset of HELIOS-B?

[Pushkal Garg, executive]

Yes. Thanks, Paul. Look, I think maybe a couple of points. As reflected previously, obviously, we're disappointed in the decision that was made. But as we look at the APOLLO-B results with regards to TAP and non-TAP, the add-on TAP group was a very small group, only 91 patients, study wasn't designed to characterize that subgroup. But we are encouraged and when we looked at the data that were presented at the ADCOM and the various congresses that the outcomes data in both groups actually are trending favorably for the patisiran arm. And that bodes well for HELIOS-B.

The other point I would just make around that is that we have an experience now in that study, as we've mentioned that we targeted operationally about 50% of patients. We've come in somewhat less than that, which certainly adds in the overall powering of the study, while we overenrolled as well by 10%. I think with regard to the add-on factor that you were mentioning from a regulatory perspective, I think one of the points that probably is worth noting is that think that point was raised in particular because tafamidis has a mortality claim and what APOLLO-B with ONPATTRO was coming forward was with a functional claim in terms of 6-Minute Walk Test in KCCQ. And so that raises questions about how these drugs are going to be used in combination or in sequence, et cetera.

In contrast, as you just highlighted, HELIOS-B is going to deliver outcomes results. And so that issue becomes much less of an issue. The other point is that we have a much larger experience in this study and much longer follow-up. So I do think that we're going to be able to look at the consistency of effect across both the monotherapy and the baseline TAP group. And that's really what we'll be focusing on. When you look at that subgroup as well as a number of other subgroups in this side.

[Operator]

Our next question comes from Luca Issi of RBC.

[Unknown Analyst]

This is Lisa on for Luca. I just want to touch base on HELIOS-B. Is it possible that you will elevate NT-proBNP and 6-Minute Walk Test as part of the composite primary end point? You obviously have shown promising results from both of those end points in APOLLO-B and in that way, if they're elevated, you would have the primary endpoint that ends up replicating bridge bio. So you could infer use that as a regulatory precedent to facilitate your conversation with [ Norman Soft ] bridge. Would that be a fair way to think about it? Any color there would be much appreciated.

[Pushkal Garg, executive]

Thanks, Lisa, for your question. Look, I think what you're pointing out in raising is the fact that when we looked at the APOLLO-B data, we did see really pretty much every endpoint lining up in favor of TTR lowering, whether it was functional, like 6-Minute Walk Test or quality of life, echocardiographic parameters and biomarkers like NT-proBNP. And so I appreciate the point that you're raising and certainly, as Yvonne highlighted, we're laser focused on delivering a successful study. We're very confident in the overall design of the study, the execution of the study I think to your point about the BridgeBio results, I think they point to the fact that in the modern era, that this is still a progressive disease despite patients being caught earlier in their disease process and then an effective therapy can show a benefit on top of that. And so -- in that setting.

So we're overall really encouraged by what the study is and how it's designing out. And as we've mentioned, we're laser-focused on this. If there are any tweaks adjustments that we make to the statistical analysis plan will follow up in due course.

[Operator]

One moment for our next question. Ellie Merle of UBS.

[Eliana Merle, analyst]

Just again, kind of on potential for combination. Just commercially, how are you thinking about the proportion of ATTR cardiomyopathy patients that will be treated with say, monotherapy versus, say, a combination with tafamidis, assuming the success of HELIOS-B? And then just from a commercial perspective, what do you think payers want to see in terms of the benefit of vutrisiran on top of tafamidis? Say, in terms of mortality, hospitalization, sort of anything coming out of any kind of initial conversations there? And then just a second quick question, what data can we expect from the Phase I [indiscernible] data this year? And will the readout include weight loss data?

[Yvonne Greenstreet, executive]

Right. So maybe we'll take your first question. Look, we believe that [ vutrisiran ] is going through a really important option for patients with a potential for a differentiated profile, given it's infrequent administration, minimal co-pays. And if you look at the progress that Tolga highlighted earlier with respect to the growth in patient demand for AMVUTTRA, patients with polyneuropathy, we believe that this is going to be a really important addition to the treatment [indiscernible] [ anterior ] physicians. Tolga, maybe you could speak specifically to how we're thinking about used with the tafamidis.

[Tolga Tanguler, executive]

Yes. I mean I think one of the points that we really need to make it clear is innovation really rules the day, and AMVUTTRA has been a game changer already in polyneuropathy, and I believe -- we believe very strongly based on our research, which is availability in cardiomyopathy is going to be important, especially if you look at our track record, in price-sensitive markets where actually tafamidis is available in Europe for polyneuropathy. We've been able to actually build an attractive business tablets versus infusion, tablet versus then subcutaneous and be able to build that business not just by net patients but also with switches.

Now in the U.S., which is similar to sort of the profile that you alluded to in terms of how we would actually think about in combination is our business is already built about -- with the mixed genotype patients -- about 20% of our patients already on tafamidis granted were indicated for polyneuropathy and tafamidis is now indicated for cardiomyopathy. We're -- obviously, for us to be able to really elucidate how the positioning is going to work out, we need the HELIOS-B data. That's going to be really important. And that will obviously inform the best way we're going to position this and the best way we're going to engage with the payers.

But again, just to give you a sense about the unmet medical need, if you look at the early access program that we have, we've already been able to enroll 200 patients because patients do progress, and we believe this is going to be an important alternative.

[Yvonne Greenstreet, executive]

Thanks, Tolga. That was a kind of great answer. With respect to your final question about KHK, we're obviously trying to avoid taking the multiple questions on the call to give everybody a chance to ask the question in respect to KHK, we look forward to seeing more data Pushkal explained at the end of the year.

[Operator]

Our next question comes from David Lebowitz of Citi.

[David Lebowitz, analyst]

You spoke earlier about talking that HELIOS-B can allow for a very differentiated profile versus other therapies in the space. And my question is regarding some of [indiscernible] of the earlier questions. Given the trial differences, they have different populations with different levels of severity, their endpoints are slightly different from each other with slightly modified statistical analysis. How easy is it going to be to actually demonstrate to physicians that a profile is actually differentiated? And what aspects of the data would you focus upon?

[Yvonne Greenstreet, executive]

One thing, maybe you can start off by maybe also reflecting on some of the data we've seen already from APOLLO-B and the 24-month data that demonstrated, actually sort of stabilization of the disease in many patients.

[Pushkal Garg, executive]

Yes, absolutely. Thanks, Yvonne, and thanks, Dave, for your question. Look, I think your -- it's important knowledge, first of all, there aren't any had data in this field, right? So what we're looking at, though, is a field that's evolving fairly rapidly, right, with -- because of the growing recognition of the unmet need, and you have -- to the benefit of patients of multiple therapies coming forward. And you're right to point out that everyone is using -- there are some variations, for example, in the way that endpoint and statistical analysis are done.

But I think what you have to do is think about it from -- if the clinician thinks about it, when they step back and they look at a patient coming in, and they're progressing with this -- they present with this disease at various stages, that's marked by [indiscernible], by exercise, fatigue, poor quality of life and you're seeing a decline over time. Their echocardiographic parameters are worsening the hardest thickening, their NT-proBNP is rising, they may develop arhythmias, et cetera. And that's what clinicians are looking at. And when they look at clinical data, I think -- what they're looking at then is, I believe, is looking at all of the data that are coming forward in terms of how is this drug -- how are these various drugs affecting the disease process.

And I think as Yvonne was alluding to, I think what we're starting to see coming out of APOLLO-B really indicates the potential for a very unique profile when you silence TTR upstream using an RNAi mechanism of action. When we are seeing really favorable effects across all of these different parameters that we've looked at whether it's functional quality of life, whether it's type of credit graphic, whether it's biomarker-based. And that -- in a disease that's otherwise steadily progressive to see stability out to 2 years on both 6-Minute Walk Test and KCCQ stands out, and I think that was quite remarkable.

So look, I think over time, as clinicians will get experience, and I think this is again where clinicians are having experiences told highlighted with AMVUTTRA -- both ONPATTRO and now AMVUTTRA for now many years, taking care of PN patients and mixed phenotype patients. I think they're also getting accustomed to the efficacy profile, the tolerability and safety profile of these medicines. So all of that helps, I think, in terms of physicians understanding of how to use medicines for their patients.

[Operator]

Our next question comes from Salveen Richter of Goldman Sachs.

[Unknown Analyst]

This is Tommy on for Salveen. So on HELIOS-B, how similar do you the APOLLO-B and HELIOS-B patient populations to be in terms of genotype and baseline characteristics? And besides the higher cap on HELIOS-B for baseline TAP user, are there any other notable differences? And do you have the flexibility to potentially push back top line data from HELIOS-B until all patients get to 36 months of follow-up, if that was seen as necessary?

[Pushkal Garg, executive]

Yes. Tommy, I think what I'd say is that in general, I would think about the patient populations and APOLLO-B and HELIOS-B as being fairly similar, right? We started the studies around the same time. The entry criteria in general are the same. As you talked about, the one exception is that we allowed for a higher baseline proportion of patients to come in on tafamidis. But by and large, I would think about these similar. And I think that's -- again, what helps us here is the fact that we've seen the positive results out of the APOLLO-B across all the different measures that we've talked about. But this study has the benefit of being twice as large and 3x as long.

The follow-up, as you know, is designed to allow for differential follow-up and really to maximize the follow-up that we have on the patients. So I think that as was asked earlier as well, I think this really maximize or optimize the power that we can sort of gain on some of the endpoints. So we're looking forward to presenting the results in early '24.

[Operator]

And one moment for our next question. [ Jessica Fai ] of JPMC.

[Unknown Analyst]

This is [ Nason ] for [ Jessica Fai ]. Assuming HELIOS-B is positive, do you envision the net price of AMVUTTRA changing from the current polyneuropathy [indiscernible] just on cardiomyopathy? Why or why not?

[Yvonne Greenstreet, executive]

Yes. So it's pretty early days yet as Pushkal said, we're expecting top line results from here being in early 2024. And really, at this point in time, I don't think it's approved for us to make any specific comments about pricing, other than to say, obviously, we want to provide value to patients physicians and ecosystem in general, according to our patient access [ clinical process ]. I think that's all we can say, that's the point in time.

[Operator]

One moment for the next question. Maury Raycroft of Jefferies.

[Maurice Raycroft, analyst]

I think it was mentioned on our recent conference call that you have the opportunity to make tweaks to the HELIOS-B fiscal analysis plan up until the database lock. Can you elaborate more on what that could entail? Would it require FDA buy-in and how this flexibility factors into your chances of success for HELIOS-B?

[Yvonne Greenstreet, executive]

Yes. No, that's a great question. Pushkal, any comments you'd like to make on the question?

[Pushkal Garg, executive]

Yes. Maury, I think I'm going to probably restate what we've talked about previously, which is it's we -- our teams are looking obviously at data in the study. We're looking at external data sets, et cetera. And as is normal in the industry has been on practice here at Alnylam, there are tweaks that can be made. In past instances, we've looked and changed from parametric to nonparametric statistical tests, et cetera. We've added subgroups, et cetera. So there are things that can be done that can help either the primary analysis or the overall data sets that are being done in terms of maybe -- it comes with prespecified analysis or methodologies that are applied. I'm not going to speculate or hypothesize about what's going to be aligned with agencies or not. So I think -- but if there's material information there, we'll certainly share that with you in due course.

[Operator]

Next question, give us one moment. Gena Wang of Barclays.

[Huidong Wang, analyst]

Maybe just follow up on Maury's question. So -- are you planning to add, say, any additional follow-up time flexibility regarding -- because right now, when I look at your slide, it's still saying the last facing follow-up each month 30. And do you have a flexibility and willingness or plan to extend to 36 months? And then another very quick question regarding tafamidis. Just wanted to make sure I heard it correctly, Pushkal, I think that you've mentioned 50% of patients on baseline tafamidis? Was that correct? Or was it close to 50%? And also regarding the tafamidis dropping, is bridge about 14% is a good benchmark for HELIOS-B?

[Pushkal Garg, executive]

Yes. Thanks, Gena. Maybe a couple of points just to clarify. So look, in terms of the study design, the study design has variable follow-up of 30 to 36 months. And so we will be following the majority of the patients out to the 36 months because of the way that enrollment occurred, but there is variable follow-up in the context of the study during the blinded portion of the study. In terms of baseline tafamidis, we had an operational target of 50%. But as we've stated previously, we came in under that number. And then with regard to drop in -- what we said is that the drop in rate remains below the assumptions that we had when we designed the study. So again, all of these offer tailwinds in terms of what we believe in the overall powering of the study. So hopefully, that helps.

[Operator]

Our next question comes from Mike Ulz of Morgan Stanley. .

[Michael Ulz, analyst]

Maybe just another follow-up on HELIOS-B. When you share the data early next year, can you give us a sense of what level detail and data that you will include in the top line results. For example, will we see that tafamidis combo subgroup analysis?

[Pushkal Garg, executive]

Yes. Thanks for the question, Mike. Look, I think as it's our norm during top line results, we will present the prespecified hierarchical endpoints, along with p-values along with an update on safety and then with subsequent data presented at a scientific congress.

[Operator]

This concludes the question-and-answer session. I'd like to now turn it back to the company for closing remarks.

[Yvonne Greenstreet, executive]

Great. Thank you, everyone, for joining us on this call. We're very pleased with our progress in the third quarter of 2023 across the business, and we look forward to sharing more progress with you in the coming months as we deliver on our goals. Thank you very much, and have a good day.

[Operator]

Thank you for your participation in today's conference. This does conclude the program. You may now disconnect.