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Greetings, and welcome to PDS Bio Clinical Programs Update Call. At this time all participants are in a listen-only mode. A brief question-and-answer session will follow the formal presentation. [Operator Instructions] As a reminder, this conference is being recorded. It is now my pleasure to introduce your host, Mike Moyer. Thank you. You may begin.

Thank you, operator. Good morning, everyone, and welcome to PDS Biotech's Clinical Strategy Update Call. Today, we will discuss the outcome of the company's recent meeting with the FDA and provide a business and clinical programs update. I'm joined on the call today by the following members of the company's management team. Dr. Frank Bedu-Addo, Chief Executive Officer; Dr. Kirk Shepard, Chief Medical Officer; and Lars Boesgaard, Chief Financial Officer. Dr. Bedu-Addo will begin with a review of the company's recent interactions with the FDA. Then Dr. Shepard will provide an update to the company's clinical development plans. Mr. Boesgaard will then join the call to help address questions from covering analysts. As a reminder, during this call, we will be making forward-looking statements, which are subject to various risks and uncertainties that could cause our actual results to differ materially from these statements. Any such statements should be considered in conjunction with cautionary statements in our press releases and risk factors discussed in our filings with the SEC, including our quarterly reports on Form 10-Q and Annual Report on Form 10-K and cautionary statements made during this call. We assume no obligation to update any of the forward-looking statements or information. Now I'd like to turn the call over to Dr. Bedu-Addo. Frank?

Thank you, Mike, and good morning, everyone. It's our pleasure to speak with you again and to provide an update on our plans to advance our lead program in recurrent or metastatic head and neck squamous cell carcinoma, HNSCC, into a registrational trial in 2024. As Mike mentioned, we've had an active dialogue with the FDA regarding the next steps in our clinical development program, culminating with a meeting with the FDA in early July. We have received the official minutes from this meeting with the FDA and are therefore able to provide this update. I'll first review the reasons for the meeting with the FDA. Over the last year, the data from our VERSATILE-002 Phase II trial of Versamune HPV and KEYTRUDA, also known as pembrolizumab, has continued to mature. And we are pleased to see clinical responses continue to improve with an impressive percentage of patients having deep and durable responses. Critically, for the program's potential success in a registrational study, we have also seen the survival data continue to mature with equally impressive median overall survival results. Kirk will walk us through the recent data. These more mature data have enabled us to revise the clinical endpoints in the statistical design section of the protocol that was discussed with the FDA, which we believe will improve the potential for a successful trial. As discussed during our May 8 KOL event, we also provided you with the recent survival update on the triple combination of Versamune HPV, PDS01ADC, and the immune checkpoint inhibitor, Bintrafusp alfa. This study also demonstrated really encouraging results in both immune checkpoint inhibitor naive and immune checkpoint inhibitor resistant patients. With this in mind, we proposed a three-arm trial to the FDA. During the meeting with the FDA, we discussed our proposal for the pivotal trial in HPV16-positive head and neck cancer with a double-combination treatment arm would be joined by a third arm of our triple-combination of Versamune HPV, PDS01ADC, and pembrolizumab. As a reminder, we had previously obtained alignment with the FDA for the double-combination of Versamune HPV and pembrolizumab with our previous statistical design. As we discussed at our KOL event on May 8, since we proposed a switch from Bintrafusp alfa to pembrolizumab, which would make it a new combination, this trial was to be preceded by a PDS01ADC dose optimization study in 40 subjects. With this background behind us, we are happy to report that we had a positive and productive meeting with the FDA. The FDA expressed support for our plans to advance both the triple and the double combinations. With respect to the triple combination, the FDA requested additional safety analysis in the lead-in PDS01ADC dose optimization part of the study. In order to avoid potential delays in initiating the randomized trial, the FDA agreed that the dose optimization should be done separately and the registrational trial of the revised two-arm, double-combination trial, VERSATILE-003 should proceed. This decision was made due to the strength of the VERSATILE-002 data that we presented in our package, the potential of the double-combination to be the market leader based on the observed combination of tolerability and survival, as well as our goal to be first two markets. As a result, our immediate focus is now to initiate the VERSATILE-003 trial with the double-combination before the end of this year. We also intend to initiate the PDS01ADC dose optimization separately with the FDA's recommendations. We believe, as previously stated, that the double-combination, which has already received a fast-track designation from the FDA, has the potential to significantly advance the treatment of HPV16-positive head and neck cancer based on the promising clinical response rates and safety. We also believe that this approach of progressing the double-combination ahead of a more extended dose optimization will help maintain Versamune HPV's current position as potentially being the first targeted immunotherapy for head and neck cancer. We look forward to the possibility of significantly advancing the treatment of the growing population of patients with HPV16-positive head and neck cancer. So as a result of this alignment with the FDA, we have contracted with a contract research organization, or CRO, to run the Phase III clinical trial, and the preparatory work is ongoing. Our VERSATILE-003 trial has a broad KOL support, including from the investigators involved in VERSATILE-002. And we have already lined up a significant number of the target sites that have indicated strong interest in participating in the trial. A lot of activities ongoing as we and our CRO are aggressively performing the prep work necessary to get the trial up and running next quarter. Now I will turn the call over to Kirk to review the data and to outline our plan for the updated VERSATILE-003 registrational trial in greater detail. Kirk?

Thanks, Frank, and good morning, everyone. As Frank mentioned earlier, our discussion with the FDA on the best path forward was informed by the recent compelling data obtained from the VERSATILE-002 trial. As we previously reported, VERSATILE-002 met and exceeded its primary endpoints in first-line recurrent or metastatic HPV16-positive head and neck cancer. Next slide. This slide shows the trial design of VERSATILE-002. This was a global multi-site Phase II study of Versamune HPV and pembrolizumab in subjects with HPV16-positive recurrent or metastatic head and neck squamous cell carcinoma. Our partner in this study was Merck. And based on the results, this treatment doublet received fast-track designation from the FDA. Regarding the study treatment, the patients receive four cycles of subcutaneous injections of Versamune HPV with both pembrolizumab and Versamune HPV given on the same day every three weeks. Then a fifth and final dose of Versamune HPV at Cycle 12. The patients could remain on pembrolizumab every three weeks for up to two years until progression or intolerability. The key entry criteria for the ICI naive subjects were the diagnosis of recurrent or metastatic head and neck squamous cell carcinoma, a HPV16-positive tumor, and a combined positive score, or CPS, equal to or greater than 1. The study design was an open-label, non-randomized design with 31 sites in the U.S. and Europe with ICI naive and ICI resistant cohorts. The population of interest for this study is the ICI naive cohort. The primary endpoint was best objective response of confirmed complete response or partial response per RECIST 1.1. Secondary endpoints were overall survival, PFS, safety and tolerability. Next slide. Now I'll show you the waterfall plot that shows tumor responses of individual patients. What stands out on this plot is a number of deep responses that resulted. 21% of the treated patients had 90% to 100% tumor shrinkage. For over 20% of our patients to have complete or almost complete responses is encouraging and one of the reasons not to delay this trial. Each bar represents a patient. The bars colored green, blue, and yellow are those who experienced confirmed complete response, partial response, or stable disease, respectively. The disease control rate as measured using a RECIST 1.1 was 77.4%, with an objective response rate of 34% for CPS score above and equal to 1, or 48% for CPS score above or equal to 20. Next slide. One of the important attributes of the Versamune platform that was demonstrated in both preclinical and Phase I studies is the memory T cell response. On this plot, we see the majority of patients who experienced tumor shrinkage have a long-lasting response. Next slide. Moving on to the most critical result in the eyes of the FDA, the survival of patients. Here, we see the Kaplan-Meier plot. The calculated median overall survival is 30 months for patients with CPS score above or equal to 1. The median overall survival of 30 months is based on a data cut as of May 17, 2024, and is consistent with the data we presented at our Key Opinion Leader event in May, which was based on a data cut of November 30, 2023. The lower limit of 95% confidence interval is about 20 months. The best reported median overall survival to date is 17.9 months with pembrolizumab from the recently presented LEAP-010 trial for recurrent or metastatic head and neck squamous cell carcinoma. Please note that every patient on this plot is counted for the standard Kaplan-Meier methodology and sensored appropriately to ensure that as of the reported data cut, each pace of status is confirmed to be reported on the plot. Of the 53 patients, 35 are censored, of which 27 remain alive and ongoing and will continue to be followed for survival. Two have been lost to follow-up and six have a withdrawn consent for further follow-up. 18 patients have died to date. Versamune HPV and pembrolizumab continues to be well-tolerated. To date, we have reported 9.2% of the patients having a grade 3 treatment-related toxicity, one patient having a grade 4 toxicity approximately one year after the last dose of Versamune HPV, and there are no grade 5 toxicities. We are encouraged with the unique combination of tolerability and clinical response and survival. Next slide. We do recognize that this study is a single-arm global multi-site study, and therefore, these results will be confirmed in our randomized Phase III clinical trial. However, it is important to highlight that a study led by the National Cancer Institute with the triple combination, provided an internal control through inclusion of a number of patients who are HPV16-negatives, and the results demonstrated the critical role of Versamune HPV in generating potent tumor-attacking HPV16-specific T cells, resulting in a superior clinical response in the HPV-positive patients. As demonstrated in this plot, 14 first-line recurrent or metastatic HPV-positive patients were enrolled, six were HPV16-negative and eight were HPV16-positive. We can see the higher objective response rate is in the HPV-positive patients. Similar results are seen with the bars to the right with a PFS. Such internal controls were important in confirming the mechanisms leading to the robust clinical responses we are seeing with HPV Versamune across all three Phase II clinical trials with the investigational therapy to date. As we announced, full data from the May 17, 2024 data cut will be presented later this quarter, and we look forward to sharing the data of this compelling combination of response, survival, and tolerability with investors and the clinical community. Next slide. As we look ahead to the initiation of VERSATILE-003, we are mindful that in recurrent and/or metastatic head and neck squamous cell carcinoma, objective response rate and progression-free survival have generally not translated into increased survival. Survival rates are well-established to be less than 18 months under the current standards of care. Based on this as well as our recent data that we just discussed, we have updated the statistical endpoints for the VERSATILE-003 double-combination study to provide an even more robust study design. In the fourth quarter of this year, we intend to have site initiation for the VERSATILE-003 Phase III two-arm clinical trial, evaluating Versamune HPV plus pembrolizumab versus the control pembrolizumab as a potential first-line treatment in patients with recurrent or metastatic ICI naive HPV16-positive tumors. With an overall survival, OS, as the study's primary endpoint, the total number of subjects in the study will be 400 to 450 with a 2:1 randomization. Next slide. Concerning trial implementation, a global CRO has been engaged in site selection, preparation, and investigator agreements. There will be approximately 130 sites in the U.S., Canada, Europe, and Latin America. The estimated time for full enrollment is 18 to 24 months. An interim analysis for OS with the possibility of an FDA accelerated review will be performed following an event trigger in approximately six months after enrollment completion. A futility analysis will be performed approximately 18 months after the study enrollment starts. As Frank mentioned, rapidly advancing the double-combination into the registrational study is now our primary focus. We remain committed to performing the dose optimization study of Versamune HPV, PDS01ADC and pembrolizumab, a triple combination in due course. This clinical strategy leverages the encouraging maturing data on survival and deep disease control from the VERSATILE-002, the program's fast-track designation, and strong support from our investigators to create a fast and efficient pathway for Versamune HPV to be the first product of its kind on the market in head and neck cancer. This trial helps us to examine the potential of Versamune HPV in patients with advanced HPV16-positive head and neck squamous cell carcinoma and also serves as a proof of concept for the Versamune platform and its ability to generate a potent target T cell attack against a variety of HPV16-positive solid tumors. We believe this data points to the potential of the Versamune platform as a significant advance in the treatment of HPV16-positive cancers and that this clinical approach represents the fastest overall path to patient access to Versamune HPV. With that, I'll turn the call over to the operator for our question-and-answer session. Next slide.

Thank you. We will now be conducting a question-and-answer session. [Operator Instructions] The first question comes from Louise Chen with Cantor. Please go ahead.

Hi. Thanks for the update call and more visibility on your path forward. Just had two quick questions for you. I wanted to ask you if you could remind us the potential market opportunity for your doublet now that you've chosen a path forward? And then also what type of data do you want to show to support a good opportunity for your drug? Thank you.

Louise, thank you very much for your questions. So one of the key things with this market is the fact that the number of incidences of HPV16-positive head and neck cancer are increasing significantly despite the HPV cancer – preventive HPV cancer vaccines. One of the recent projections is that this specific indication, head and the cancer, will continue to rise significantly into the mid-2030s, primarily driven by HPV16, and continue to remain at this high level for the next couple of decades. And so HPV16-positive head and neck cancer remains a huge unmet medical need and a huge opportunity for uneffective therapy. Today, these patients are treated the same way HPV-negative patients are treated. And one of the key things that KOLs and oncologists are looking for is something that treats this underlying cause of this deadly devastating disease, which is increasing and incidents quite rapidly. The current market opportunity for our product, specifically addressing the late-stage recurrent metastatic disease, is somewhere between $1.5 billion to $2.3 billion. And this was an estimate that came in through independent market research. Louise, did that answer your question?

Yes, it does. Could I actually squeeze in one more quick question? I just wanted to ask you also on your futility analysis. Is that a go/no-go decision or just the first look at the data?

So the futility analysis, we won't actually have a look at the data. That will be between our data monitoring committees and our statisticians. And that will really be to – so we are not really going to be announcing data at that point. It's really going to be updating as to whether we've met the futility that we're looking for and the trial continuing.

Thank you. Thank you very much.

Welcome.

Thank you. The next question is from Mayank Mamtani with B. Riley Securities. Please go ahead.

Good morning team. Thanks for taking our questions and good to hear and FDA agreed upon path for doublet and triplet. So maybe just on the details of the triplet dose optimization cohort. Could you talk to what dose-ranging work you're looking to do here, dose levels and what endpoints you're powering this cohort for and essentially maybe update us when we can see the first data from that cohort? And then I have a follow-up.

Sure, Mayank, thanks a lot for your question. So the dose optimization study is really as we proposed at the KOL event. So based upon the fact that we're switching over from Bintrafusp alfa, which was the Merck KGaA checkpoint inhibitor to pembrolizumab, this essentially becomes a new combination. And based upon that, even though dose optimization of that asset on its own has been done, and has been administered to over 300 patients to date, we still have to optimize the dose in this novel combination itself, right? And so based upon the fact – based upon the knowledge and the fact that we have from the dose optimization of the monotherapy, where we know that the effective dose is 12 micrograms per kilogram and above, what we proposed and discussed at the KOL event on May 8 was that we're actually going to be looking at two doses, the 12 microgram dose and the 16.8 microgram dose. The FDA was fine with this plan. And so that's really the focus of that study, is to look at those two doses and try to determine if one dose is more effective or safer than the other, right? And so the key outcomes would be some safety parameters as well as efficacy. We'll be looking at objective response rate primarily to make that decision as to which of those two doses would be the best to move forward. So one of the things we're doing now is we've taken the FDA's feedback. We had really good discussions. And I think the key for us now is our focus is really getting the duals, the pembro-Versamune HPV trial up and running. Once that is up and running, we'll then shift our focus to determining the timeline and when we get the dose optimization portion started. So we'll keep the markets updated on the timelines for that study. But for now, right now, our primary focus is really to make sure that we can get this doublet trial up and running as quickly as possible.

That’s helpful. Thank you. And then on the Phase III doublet, if you could clarify your plan to secure KEYTRUDA supply? And could you maybe also talk to your control arm survival assumption as part of the powering? Your sample size obviously looks pretty robust, about 400 patients. But I was just curious how your underlying study powering assumptions are and what you're baking in based on a lot of the recent studies on the control arm for survival?

Well, Mayank, I'll start answering then I'll hand over to Kirk, if there are any things Kirk would like to add to the answer. So in terms of supply of pembro, that's a discussion that's between Merck and PDS that we have not made public yet. We'll update the market if there are any decisions on that end in the future. In terms of the clinical design, you're right. So we do know that even though the KEYNOTE-048 study reported and median overall survival of about 12.3 months, more recently, the LEAP-010 trial and reported a median overall survival of 17.9 months. And so for us to be conservative, we assume that our control arm is going to be closer to what we saw – what was reported in the LEAP-010 trial. What we've also done here is it's a 2:1 design, right? And so we give our patients a 67% chance of getting on the treatment arm. But that also means that these studies are designed with survival, we're looking at death events occurring. And so we anticipate that with a 2:1 arm, you'll have a slightly lower number of death events unfortunately from the control arm. And based upon those statistics, the trial size increases a little bit because you expect fewer death events and those death events to take longer to achieve that specific endpoint, so you need more patients to do that. And we're looking at hazard ratios of about 0.7. So really, what I would call a conservatively designed trial, we want to maximize our potential for success with this trial. I'll hand over to Kirk and see Kirk has anything to add to what I just said.

Frank, that pretty much covered except for the lower bounds are figured to be conservatively 18 months for the control. As Frank just mentioned, the best results we've had is from LEAP-010, which was 17.9% survival. The upper limits are also conservative. As you know, we just presented a 30-month median overall survival. And that is set at 27 months. So we think it's a conservative estimate of the differences. And as Frank said, it gives us a hazard ratio of 0.67. Sorry, point to the investigators also was a 2:1 randomization. They felt that more patients have the ability to get this drug the better. So not only were they emphasizing to us feed in efficiency as far as getting this doublet to the market, but also having the randomization 2:1. Sorry, I maybe interrupted you.

No. Thank you. That color was helpful. And maybe just a last question for me. The ESMO abstract that you have been granted acceptance, can you just maybe clarify what updated – I believe it's for the doublet – what incremental data we will get there, or is it mostly socializing with the clinical academic community, the data that we are obviously talking about today? And thanks again for taking our question.

Yes, we'll provide some additional updates on that topic, Mayank. But yes, this will cover updated data.

Got it. Thank you.

Thank you. The next question comes from Joe Pantginis with H.C. Wainwright. Please go ahead.

Hey, everybody. Good morning. Thanks for taking the questions and the updated visibility. Two questions first. So are there any outstanding questions with the FDA that still need to be addressed? And then number two, I was just wondering if you could spend a moment discussing the rationale for replacing Bintrafusp alfa with KEYTRUDA?

Hi, Joe. Thanks very much for your question. I'll start with the first question, which is outstanding questions. No, we have the go-ahead to get this trial going. So there are no outstanding issues that have to be resolved with the FDA pertaining to getting our trial, the VERSATILE-003 trial, up and running. And with regards to the conversion from Bintrafusp to pembro, primarily, as you know, Bintrafusp is not an FDA-approved checkpoint inhibitor. So it is an investigational checkpoint inhibitor. And so going into a triple-combination trial with three investigational agents becomes quite a complicated regulatory pathway, which is what we want to avoid. And also based upon the fact that we have seen really good synergy, potential synergy between our Versamune HPV and pembro with some of the results that we've presented today, that – we're highly encouraged and felt that, that could form a solid foundation to which the PDS01ADC could be added to further enhance the responses, the already strong responses we've already seen with the doublet. And so those were the considerations that led us to make the determination to switch from the investigational checkpoint inhibitor to the FDA-approved checkpoint inhibitor that we've already shown really good synergy with both from a safety perspective as well as response rate and survival.

Thanks for that. And then obviously, the concept of futility analysis is quite clear. And I was just curious, as you move towards the interim analysis that you discussed in your prepared comments, is this something that will be just with the DSMB looking at it, or will there be publicly disclosed data anticipated?

The futility will be simply the DSMB, but the interim readout would be made publicly available, those results. And the interim, as Kirk mentioned, is also based on an overall survival endpoint. And so that gives us pending what the data looks like, that gives us, we believe, a strong opportunity for potential accelerated approval.

Got it. And then my last question, I think, revolves around what do you anticipate the BLA looking like? Because obviously, there's a built-in 52-week OLE in the Phase III study. I guess looking at the totality of the safety database needed for the BLA, would you be able to file on a potential accelerated approval? Sort of what's the best case and other case scenarios for filing a BLA?

Well, as you know, we don't want to speculate too far as to what's going to happen, but we absolutely intend to take advantage of our fast-track designation to have continuous discussions with the FDA as this trial progresses, right? So I think in terms of the BLA and the key elements of that BLA filing and what we would need, I think we'll be able to update you when we get closer to that interim data readout. But we certainly will take advantage of the fast-track designation to have those continuous discussions with the FDA as we get closer to that point.

Absolutely. Appreciate all the commentary, Frank.

No problem. Very welcome. Thanks.

Thank you. There are no further questions at this time. I would like to turn the floor back over to Dr. Frank Bedu-Addo for closing comments.

Thank you. Well, thank you very much. I would like to thank all of you for attending our update call this morning. As I expressed, we are extremely pleased with the positive maturation of the VERSATILE-002 data. And I'm sure you can see why from the totality of the data that was presented from the durable disease control and depth of responses to survival and tolerability. Our primary focus is now to activate the registrational trial of Versamune HPV and pembrolizumab with the goal of significantly advancing the treatment of HPV16-positive head and neck cancer. We will keep you updated on our progress with the study. We will also provide future updates on the triple-combination dose optimization. Thanks a lot again, and wish you all a great day. Thank you very much.