Dynavax Technologies Corp

NASDAQ:DVAX

Earnings Call Transcript 2024-Q1

[Operator]

Ladies and gentlemen, thank you for joining us today. This concludes today's conference call. You may now disconnect. Everyone, have a wonderful day. Good day, ladies and gentlemen, and welcome to the Dynavax Technologies First Quarter 2024 Financial Results Conference Call. [Operator Instructions]

I would now like to turn the call over to Paul Cox, Vice President, Investor Relations and Corporate Communications. Please begin, sir.

[Paul Cox, executive]

Thank you for participating in today's call. Joining me from Dynavax are Ryan Spencer, Chief Executive Officer; Donn Casale, Chief Commercial Officer; Rob Janssen, Chief Medical Officer; and our Interim of Head of Finance, Rita O'Connor.

Earlier today, Dynavax released financial results for the first quarter ended March 31, 2024. Copies of the press release and the supplementary slide presentation are available on Dynavax's website. Before we begin, I advise you that we will be making forward-looking statements today based on our current expectations and beliefs, including, but not limited to, potential market sizes, market segmentation, effective marketing efforts, future expected market share and related growth rates and related ACIP recommendation impact on each financial guidance and trends, including revenue, profitability, cash flow and sufficiency of current capitalization, timing and results of FDA submissions, clinical trial starts and data readouts and potential future uses of or demand for our CpG-1018 adjuvant.

These statements involve risks and uncertainties, and our actual results may differ materially. These risks are summarized in today's press release and detailed in the Risk Factors section of our SEC filings, including today's quarterly report on Form 10-Q. Our forward-looking statements speak as of today, and we undertake no obligation to update such statements.

And with that, I will now turn the call over to Ryan.

[Ryan Spencer, executive]

Thanks, Paul. Good afternoon, everyone. Thank you for taking the time to join us to review our Q1 2024 results. The first quarter of 2024 saw continued year-over-year growth in quarterly HEPLISAV-B net product revenue despite a slight decrease in the U.S. hepatitis B vaccine market during the first quarter. Due to an extended cough, cold and flu season, which reduced the number of vaccination opportunities a dynamic which was observed across other nonrespiratory vaccine markets beyond hepatitis B.

Even with the slow start to the year, we remain very encouraged about the adult hepatitis B vaccine market opportunity, both in 2024 and over the longer term. We are seeing a pickup in the market in recent weeks as providers have begun to shift to nonrespiratory vaccine campaigns and as our retail pharmacy partners and top IDN systems launched new hepatitis B-focused initiatives. HEPLISAV-B became the market share leading hepatitis B vaccine for adults in the U.S. last year, and we plan to build on that position in 2024.

We continue to expect record HEPLISAV-B in 2024, with net product revenue expected in the range of $265 million to $280 million for the year. Longer term, the U.S. adult hepatitis B vaccine opportunity remains significant with over 130 million patients eligible , one of the largest addressable patient populations in the U.S. with a vast majority remaining unvaccinated. We believe this translates to a market opportunity for HEPLISAV-B of over $800 million by 2027, with HEPLISAV-B poised to achieve a majority market share.

We're also excited for several upcoming milestones from our novel vaccine pipeline, including the initiation of our Phase I/II trial for a shingles vaccine tense long-term follow-up data for our Phase I TdaP trial and data readouts from our play program. As a reminder, we look forward to our PDUFA action date on May 13 for HEPLISAV-B supplemental BLA for vaccination of adults on hemodialysis, which is currently under review by the U.S. FDA.

In addition to this continued execution and bolstered by our strong financial position, we continue to assess opportunities to grow beyond our internal organic pipeline within the infectious disease space, which we believe would enable us to further diversify our product portfolio and create future commercial opportunities. As we've discussed previously, we remain committed to disciplined capital allocation focused on generating significant value and driving growth. We look forward to providing updates on these efforts in the future.

I'll now turn the call over to Donn and Rob who will provide more details on HEPLISAV-B results and our pipeline progress, respectively, before Rita O'Connor reviews our financial results for the first quarter. As previously announced, our CFO, Kelly MacDonald, is currently on maternity leave, as Rita has stepped in as Interim Head of Finance, supporting me and my temporary appointment as Principal Financial Officer until Kelly's expected return in August. Donn, can you take it away?

[Donn Casale, executive]

Thank you, Ryan. In the first quarter of 2024, HEPLISAV-B achieved strong net product sales despite headwinds that affected the nonrespiratory vaccine markets, including hepatitis B. On our last call, we said that growth in the U.S. hepatitis B vaccine market was expected to be flat during the first quarter due to an extended cough, cold and flu season. As expected, these dynamics played out ultimately reducing the opportunity for adult vaccination in Q1, leading to a slight decrease in the hepatitis B vaccine market compared to the fourth quarter of last year and a flat year-over-year growth compared to the first quarter of 2023.

This dynamic has been observed across other nonrespiratory vaccine markets as well. HEPLISAV-B continued to increase its total U.S. market share year-over-year, achieving an estimated 41% market share in the first quarter compared to 37% during the same period last year. Net product revenue in the quarter grew 10% year-over-year compared to the first quarter of 2023. This sales growth continues to be driven by HEPLISAV-B's strong performance in 2 critical segments: retail pharmacy and integrated delivery networks or IDM. We estimate these segments will drive significant growth and represent over 60% of the total adult hepatitis B market in the U.S. by 2027.

In both segments, HEPLISAV-B's first quarter estimated market share increased to approximately 55% compared to approximately 49% during the same period last year. Despite the softness in the market in the first quarter, we continue to see indicators of U.S. market expansion from the ACIP universal recommendation for adult hepatitis B vaccination reaffirming our confidence in a sizable market opportunity and long-term revenue growth potential for HEPLISAV-B. Large health systems and providers are gaining awareness and agree they need to act on the ACIP universal recommendation.

Many large systems have committed to launching new hepatitis B-focused initiatives over the next several quarters to effectively implement the recommendation. Over half of our targeted IDM universe has increased hepatitis B dose volume year-over-year. While system level changes take time to enact, we are encouraged by the progress we see as our systems work to implement operational changes to support routine adoption of the ACIP universal recommendation. In the Retail Pharmacy segment, we have made meaningful progress with several large national chains, placing HEPLISAV-B in a preferred position among adult hepatitis B vaccines.

Despite the slow start in Q1, retail customers are mobilizing around the opportunity that HEPLISAV-B vaccination. Several customers have indicated a clear shift away from respiratory vaccines to a focus on nonrespiratory vaccines such as hepatitis B. Given these positive trends and customers' commitment to prioritize hepatitis B vaccination for the rest of the year, we are forecasting the retail segment to meet our annual expectations for 2024 and make a considerable impact to HEPLISAV-B's success this year.

As Ryan noted, we are reaffirming our full year 2024 net product revenue guidance for HEPLISAV-B to be in the range of $265 million to $280 million. As mentioned, we've already seen signs of the market strengthening early on in Q2 as the focus of health care providers and retail pharmacy shifts back to prioritizing nonrespiratory vaccines. We are extremely confident in the long-term expansion of the U.S. hepatitis B vaccine market and forecast annual market growth of approximately 10% to 15% over the next several years, with HEPLISAV-B gaining meaningful increases in total market share over that time.

We continue to expect the hepatitis B vaccine market opportunity for HEPLISAV-B to grow to over $800 million in the U.S. by 2027, from approximately $525 million in 2023. In summary, we are reaffirming our confidence that HEPLISAV-B will strengthen its position as a clear market share leader in the expanding hepatitis B vaccine market, and we expect 2024 will be another year of record sales and continued growth. We are very proud of our commercial team's execution in establishing HEPLISAV-B as the market share leader in the U.S., and we look forward to continuing this momentum in the remainder of 2024.

I will now turn the call over to Rob to take you through our clinical pipeline.

[Robert Janssen, executive]

Thank you, Donn. We continue to make progress advancing our innovative vaccine pipeline which is focused on leveraging our CpG 1018 adjuvant with proven antigens. Starting with our shingles vaccine program, Z-1018. As a reminder, we believe there's an opportunity to develop an improved shingles vaccine given the challenging tolerability profile of the current market-leading product.

One of the unique advantages we believe of our CpG 1018 adjuvant is its safety and tolerability profile combined with its ability to induce strong CD4 positive T cell responses, which we believe are critical to preventing the reactivation of disaster virus. We previously conducted a Phase I trial of Z-1018 in 150 subjects at clinical sites in Australia. We believe the results from this trial support the continued development of Z-1018 as they demonstrate the opportunity to develop a shingles vaccine with an improved tolerability profile and comparable efficacy.

Late last year, we received Type B meeting feedback from FDA on the Z-1018 program, which we believe is supportive of our proposed clinical development plan that includes a pivotal placebo-controlled efficacy study. During the second quarter of 2024, we plan to initiate a randomized active controlled Phase I/II trial to evaluate the safety, tolerability and immunogenicity of Z-1018 compared to the licensed recombinant vaccine. We plan to enroll approximately 440 healthy adults aged 50 to 69 years at trial sites in Australia. We will be evaluating escalating doses of our GE protein, our selected dose of CpG 1018 with or without alum and different vaccination schedules.

We anticipate top line immunogenicity and safety data in the second half of 2025, which will include a comparison of CD4 positive T cells 1 month after the last vaccine dose. In March, we received FDA clearance of our IND application for this trial. Turning next to the TdaP-1018 program. This is an investigational vaccine candidate that's intended for active booster immunization against tetanus, diphtheria, and pertussis or TdaP. Current TdaP vaccines have limitations, including waning effectiveness. And we believe there's an opportunity to improve the duration of protection using our CpG-1018 adjuvant to generate a TH1-biased immune response.

In 2022, Dynavax reported top line results from a Phase I clinical trial evaluating the immunogenicity and safety of a booster dose of TdaP-1018 compared to an active control. The results demonstrated that TdaP-1018 was generally well tolerated and induced similar or higher antipertussis antibodies and booster response rates than the active control. Prior to advancing TdaP-1018 into a previously announced Phase II human challenge trial, Dynavax plans to evaluate the persistence of pertussis immunogenicity of TdaP-1018 through a long-term follow-up study of participants who completed our Phase I trial.

The extension study is expected to follow participants for up to approximately 3 years following vaccination. Top line results are expected in the fourth quarter of 2024. These data will provide us with a view of how the TdaP-1018 immunogenicity response over time compares to the active control. And will help establish our views on the potential benefits that can be achieved with our vaccine candidate.

Moving on to the plague vaccine program, which is in collaboration with and funded by the U.S. Department of Defense. In March, we executed a contract modification with DoD to add approximately $4 million to support CMC work for the plague vaccine candidate with the agreement now totaling $38 million through 2025. We anticipate top line data from both the randomized active control Phase II clinical trial as well as the nonhuman primate challenge study of the plague vaccine candidate in the fourth quarter of 2024. These data will inform next steps for the program.

We're pleased with this progress across our pipeline, and we look forward to executing on these upcoming milestones in the coming months. We also continue to identify new opportunities to leverage our CpG-1018 adjuvant through multiple innovative programs with biotech and academic collaborators. I'll now turn the call over to Rita to review our financial results.

[Unknown Executive]

Thank you, Rob. I'll review the key financial results for the first quarter of 2024 and as well as our financial guidance for the full year of 2024. Please note that all financial comparisons are versus the prior year period, unless otherwise noted. Please refer to our press release and Form 10-Q for more detailed financial information. Starting with HEPLISAV-B, net product revenue grew 10% year-over-year to $48 million in the first quarter of 2024.

Cost of product sales for HEPLISAV-B in the first quarter of 2024 decreased to $11 million compared to $15 million for the prior year period. The decrease was primarily due to lower per unit manufacturing costs as a result of previous process improvements, partially offset by a $1 million inventory write-off charge recorded during the first quarter of 2024. We continue to be pleased with the HEPLISAV-B margin profile trend with gross margin of about 77% in Q1 of 2024, a significant improvement over the 66% in the first quarter of 2023.

We continue to expect gross margins of approximately 80% and for the full year of 2024, which is consistent with our long-term expectations of margin profile for HEPLISAV-B. Other revenue was about $3 million for both the first quarter of 2024 and 2023, representing revenue related to the plague vaccine program in collaboration with and funded by the U.S. Department of Defense.

Turning to our expenses. Research and development expenses were $14 million for both the first quarter of 2024 and 2023. Expenses in 2023 included the completion of clinical trials for our pipeline programs, whereas the first quarter of 2024 reflected activities for planned clinical trials as well as increases related to investments in our CpG-1018 preclinical and clinical collaborations.

Selling, general and administrative expenses for the first quarter of 2024 were $44 million compared to approximately $37 million for the prior year period. The increase was primarily driven by increased head count and other investments supporting our strategic growth, including an overall increase in targeted commercial and marketing efforts designed to increase HEPLISAV-B market share and maximize the opportunities presented by the ACIP's universal recommendation.

Sublease expense was $1.6 million in the first quarter of 2024 compared to sublease income of $1.6 million in the prior year period. This change reflected the termination of our original lease with a noncash charge of $3.5 million, partially offset by income of $1.9 million during the period. Including this onetime noncash charge, we expect to record approximately $5 million of net sublease income for the full year of 2024. These results generated a net loss of $9 million in the first quarter of 2024 compared to $24 million during the prior year period.

Moving to the balance sheet. We ended the first quarter of 2024 with cash, cash equivalents and marketable securities of $724 million, which we believe is sufficient to progress our current pipeline assets and support our organic base business without the need to raise additional capital. And now to summarize our financial guidance, we are reaffirming our prior full year 2024 financial guidance as follows: HEPLISAV-B net product revenue expected to be between approximately $265 million and $280 million including approximately $3 million in ex U.S. sales through our commercialization partnership in Germany.

We expect HEPLISAV-B gross margin of approximately 80% for the full year of 2024. We expect R&D expenses to be between approximately $60 million and $75 million. We expect SG&A expenses to be between approximately $160 million and $180 million. And we also expect cash, cash equivalents and marketable securities to be higher at the end of '24 as compared to December 31, '23, reflecting our continued discipline towards allocating capital to drive top line revenue growth while thoughtfully advancing our research programs.

I would now like to turn the call back over to Ryan before we start the Q&A section.

[Ryan Spencer, executive]

Thanks, Rita. In closing, we believe that our strong financial position and proven ability to execute, we are well positioned to drive sustainable growth in our core HEPLISAV-B business by capturing majority U.S. market share and leading the expansion of the adult hepatitis B vaccine market. We look forward to progressing our R&D portfolio of vaccine candidates, while continuing to be extremely thoughtful on how we allocate our capital to accelerate growth and build beyond our current base business.

We are excited about our progress to date, and we look forward to continuing to deliver on our goals for this year and beyond. Thank you, everyone, for your attending today. Operator, we would now like to open the Q&A portion of the call.

[Operator]

[Operator Instructions] Our first question will come from the line of Matthew Phipps with William Blair.

[Matthew Phipps, analyst]

First, I guess, the retail market share, it looks like it did dip a little bit from Q4 to Q1, 58% to 55%. I realize one of these are somewhat assumptions, but just wondering if there's anything lumpy in there? Or did anything else change with any contracts that caused that to happen?

[Donn Casale, executive]

Matt, it's Donn. Nothing really changed. I mean market share, there will be slight variations in market share. I mean, it's related to purchasing patterns of some of our larger customers. But for us, we continue to expect to take market share both in retail and as well an IDN. So it's really more so around the purchasing patterns of some of the larger customers.

[Matthew Phipps, analyst]

Rob, a question on the shingles program. One, could you just maybe tell how many total arms are in the trial? Just kind of wondering how many pace will be in these trial to get a sense of powering you might have for the immunicity endpoint? And then also, did you -- I can't tell if you confirm that a potential pivotal trial would be placebo-controlled? Or that's just kind of still the hope and you need to still have those conversations?

[Robert Janssen, executive]

So Matt, we will be enrolling 10 arms to receive Z-1018 and then a [ Shingrix ] arm. So there will be 11 arms with 40 subjects in each arm. And -- which is a reasonably large number for a Phase I study, but it's really -- so we can get a good sense of what CD4 responses are. Now with respect to placebo controlled, we have communicated with the FDA and heard from them that, that placebo-controlled efficacy study would be acceptable for review for a license.

[Matthew Phipps, analyst]

Great. And then maybe one last one for Ryan. Do you almost hesitate to make any real big decisions with regards to your cash balance until you see that immunogenicity data from the shingles program in the second half of next year? Is that almost -- you just kind of want to make sure you have all your options open until you get to that data? Or is that not the case? .

[Ryan Spencer, executive]

No. It's certainly one of the elements on how we think about managing our capital position. One, we talked a lot about this. We're in a favorable position to be able to fund our development programs as well as the opportunity to settle or convert when it comes due in '26. And so we like to be able to maintain all of our optionality as it relates to being able to advance our pipeline. So it's definitely a factor in how we manage our capital structure overall.

[Operator]

Next question comes from the line of Paul Choi with Goldman Sachs.

[Kyuwon Choi, analyst]

I also want to follow up on shingles as well. And can you maybe comment on how you thought about the trial design for your study, particularly in the context of recent data from [indiscernible], which showed 100% immunogenicity. Any thoughts on patient selection and or trial design endpoints and such that you can comment on and just where you think you can possibly show the most differentiation, either on efficacy and/or safety?

And secondly, just with regard to HEPLISAV-B. Can you maybe just comment on just sort of retail chain behavior? The share gains continue to look good, but just curious if you're seeing more activity, if you could elaborate a little bit more on the activity levels in the retail channel, in particular.

[Unknown Executive]

Thanks, Paul. Rob, why don't you take the first question on shingles and Donn, you can address the retail question.

[Robert Janssen, executive]

Right. So the study really is going to identify the antigen, the GE antigen. This is the first time our GE antigen. This is a first in humans, first time it's been in people. So we'll be looking at different levels of antigen. So the trial is designed to look at different levels of antigen to increase CD4 accounts. And we'll also be looking at different regimens. We're looking at a couple of different regimens in terms of time between doses. Again, to increase CD4 counts.

Now to look at reactive genicity we're developing and we've been communicating with FDA about it and how to go about doing it, and that is reactogenicity and how can we design future studies that would be label-enabling to put reactogenicity data in the label, and we're looking at sort of a standard global impression of severity changes in symptoms, health related quality of life, those types of already instruments that already exist, but we'll also be looking to develop potentially our own instrument in this study and then to validate it for use in a Phase III study.

[Unknown Executive]

And Paul, just to put a finer point on it. When we think about the ways to measure immunogenicity, we've been very clear and transparent that we believe that CD4s are critical for this vaccine. And so when we think about the way we've talked about our data, it's been very deliberate to be focused on what we think is the most -- some of the most critical endpoints. There's a variety of ways to measure immunogenicity with percentages of response to different measures. But for our trials, we've been very clear about the importance of CD4s and that's what we will continue to focus on as we progress.

[Donn Casale, executive]

Paul, it's Donn. To put a bit more color on the retail behavior. There's been a dramatic shift, if you will, in the Retail segment as it relates to nonrespiratory vaccine and focused on those vaccines coming off the respiratory season. We're seeing certainly a lot of focus by those retailers as it relates to various tactics to increase awareness to continue to run initiatives, both not only awareness for the pharmacists themselves, but also advertising out to consumers.

They're all rolling around the fact it may hepatitis B awareness month. There's a lot of focus again on setting up the infrastructure, if you will, to take advantage of that opportunity as well. So again, a drastic shift, if you will, a focus by the retail chains as it relates to hepatitis B vaccination.

[Operator]

Our next question comes from the line of Jon Miller with Evercore ISI.

[Unknown Analyst]

This is [indiscernible] on from Jon. I guess first one on HEPLISAV. How is the seasonality profile developing as the market gets more penetrated? Do you expect to see -- when do you expect to see the biggest growth for the remainder of the year? And I guess second on TdaP, I guess, why delaying the TdaP Phase II trial? And how will the Phase II design change based on learnings from the extension of Phase I?

[Unknown Executive]

Okay. Let me comment on seasonality first and Donn, if you have anything to add, please feel free. It's pretty clear that Q2 and Q3 will -- we expect will continue to be the largest quarters in the adult hepatitis B vaccine market for a variety of reasons. And I don't -- I think the market growth doesn't really change the belief that we still believe Q2 and Q3 will be the largest quarters of the year and the years in the future, recognizing that we do expect there will always be seasonality due to the fact there's significant respiratory vaccine given in the Q4, Q1 time period. So we expect that seasonality to continue even as we see market growth. Donn?

[Donn Casale, executive]

And then I think the other question, just at a high level, on TdaP. I'll take that too. And Rob, please add any color that you feel is important. But the decision here to delay the Phase II challenge study was as response to the regulatory feedback that we received related to the PR positive versus PR negative strain for pertussis, recognizing that the FDA is interested in the PR negative strain that we would conduct in the future. We did need to conduct a positive pilot study now, and we decided to make the decision to focus on PR and negative strength in the future when available, which also happen to allow us to see the results of this Phase I extension study.

So it doesn't have an impact on the overall time line, but it does allow us to have insight into the durability of our product. prior to advancing any other clinical studies. So all in all, I think a pretty -- actually a very favorable opportunity to be able to increase our understanding of the product before investing further in additional clinical trials.

[Operator]

Our next question comes from the line of Ed White with H.C. Wainwright.

[Edward White, analyst]

Just to stay with the TdaP. So how is the timing of the Phase II going to be affected? When do you expect to start that study?

[Ryan Spencer, executive]

As the Phase II, we started -- it really is still kind of up in the air. We do need to have the PR negative strain available and that's being developed. So it depends on the availability of that strain. I think the key point, though, is that study is one component of the overall development plan. The longer lead times in this development plan will be the immunogenicity data, which, in our view, it's going to be critical to have that data develop over time to show durability that can be part of our submission.

So the TdaP challenge is not on the critical path. I think is the way to think about it. It's a very valuable study because it will show the antigens are efficacious, which we have a high confidence that they will be -- and that with the presence of our adjuvant, we expect to improve over existing vaccines. So ultimately, what will gate that timing will be the availability of the PRN negative strain.

[Edward White, analyst]

Okay. And as you have the BLA -- or excuse me, the PDUFA on May 13 for hemodialysis patients, I'm just wondering if you can quantify what that means to the -- what the impact could potentially be not only this year but going forward?

[Ryan Spencer, executive]

Yes. I mean I think we've talked about this a little bit in the past that the -- yes, you already noted that May 13 is the PDUFA date. It's too really too early to comment on the impact of any -- of revenue expectations. But we will know as we've said in the past, obviously, it does take time to engage customers and merely having the PDUFA, it's the -- it gives us that license to hunt and actually engage them commercially. So we'd expect that it's going to take time, like with any other customer to be able to engage them in an effective manner. So we made no comment on the revenue expectations from this particular regulatory event, but we will continue prior updates as we progress.

[Operator]

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

[Philip Nadeau, analyst]

One follow-up question on seasonality. Appreciating -- it's probably a hard question since we're all dealing with imperfect information. But do you have a sense as to whether this year, the seasonality was particularly bad given that it was early in the availability of RSV vaccines and people are still getting shots for COVID? Is there any reason to think that the seasonality and the decline in the [ HPB ] market in Q4 and Q1 won't be as bad in future years? Or is that just hard to know at this point?

[Donn Casale, executive]

Phil, it's Donn. I think it's a little hard to know. A little early to kind of call it. But certainly -- and the feedback we've been receiving from our retail customers, in particular, is learning new vaccines, RSV, COVID, a lot was thrown at the retailers all at once. Now that they've gone through it once, going into this year, they'll be better prepared to understand what's going to be in store for that respiratory season. So we sort of see that as an opportunity moving forward, but probably too early to tell how it looks every year thereafter.

But certainly, we expect this year to be a little bit different because our customers are a little bit more prepared or anticipating the onslaught of all these different vaccines in the space. I also remember the winter season and how cough, cold and flu, COVID other things, those are variables as well as how they impact wellness and other opportunities for vaccination. So that's going to always be variable across the season. So we just have to keep that in mind that it's not only market dynamics. There's also disease dynamics at play that will be variable.

[Philip Nadeau, analyst]

The RSV vaccines have a requirement that patients not be vaccinated for something else like HBV for weeks before or weeks after receiving the RSV vaccine?

[Unknown Executive]

RSV -- was that -- did you say the RSV vaccine?

[Philip Nadeau, analyst]

Yes. Specifically for RSV, is there required to be a window of no other vaccinations around that vaccine?

[Unknown Executive]

No, not in particular. You -- just be aware, Phil, the comment data, as you usually doesn't -- specific -- how -- it's very rare for there to be specific information around how to treat other vaccines within one vaccines label. So...

[Donn Casale, executive]

Phil, it's more around the operational hurdles, quite frankly, about just operationalizing a new vaccine and vaccine launches versus [ oncovin ] administration being the barrier for our retailers in particular.

[Philip Nadeau, analyst]

Got it. And in terms of hemodialysis, I think in the past, you've suggested that there is some use of HEPLISAV already in the market. Can you remind me if that's true and if you have any estimates of penetration in the hemodialysis market currently?

[Unknown Executive]

Yes. No, there's definitely utilization in the marketplace. So yes, and you're right. We have commented on that before. We have not commented on specific penetration or share other than our comments on retail and IDN. And like we have said before, until we have our PDUFA, our BLA approved, we're going to refrain from getting into too many details on this segment.

[Operator]

Our next question will come from the line of Roy Buchanan with Citizens JMP.

[Unknown Analyst]

Just a quick follow-up on TdaP. I guess how many patients are you expecting in the extension trial? And it says in the press release versus active control. So are you going to be looking at both the TdaP-1018 and the Boostrix arms. It seems like a lot of patients have probably been off the trial for a while, maybe gone on to other things. Are you going to look at both the adults and the adolescent?

[Robert Janssen, executive]

We'll just be looking at -- yes, we'll just be looking at the young adults, Roy. We won't be looking that much [indiscernible] too few. And the number of subjects we were looking to try to enroll was up to 50. We'll be comparing TdaP-1018 to Boostrix.

[Unknown Executive]

Yes. And Roy, just a couple of elements there. You already noted the trial was conducted a while with us. So we'll have 2 to 3 years of follow-up on these patients. And the ultimate number is going to be depending on how many we can get to return given some of the challenging factors you noted, but we expect that we'll be able to have some interesting data from the follow-up.

[Operator]

We have no further questions at this time. I would now like to turn the call over to Mr. Ryan Spencer, Chief Executive Officer, for closing remarks.

[Ryan Spencer, executive]

Thank you, operator, and thank you all for joining us today. We appreciate your interest in Dynavax. We are excited about our recent accomplishments and the strength of our position. We look forward to updating you on our progress focused on protecting the world against infectious diseases. Operator, you may end the call.

[Operator]

Ladies and gentlemen, thank you for joining us today. This concludes today's conference call. You may now disconnect. Everyone, have a wonderful day.