Ladies and gentlemen, thank you for standing by and welcome to the Atara Biotherapeutics Second Quarter 2020 Financial Results conference call. At this time, all participant lines are in a listen-only mode. After the speaker's presentation, there will be a question and answer session. To ask a question during the session, you will need to press star one on your telephone. Please be advised that today's call is being recorded. I'd now like to hand the call over to Eric Hyllengren, Vice President of Investor Relations and Finance at Atara Biotherapeutics. Thank you. Please go ahead, sir.
Thank you, operator. Good afternoon, everyone, and welcome to Atara's second quarter 2020 conference call. On today's call, members from the Atara executive team will provide an update on our financial results and operational progress, and also review our upcoming key milestones and objectives for 2020. Earlier today, we issued a press release announcing our second quarter 2020 financial results and operational progress. This press release and an updated investor presentation are now available in the investor and media section at atarabio.com. Joining me on today's call are Dr. Pascal Touchon, President and Chief Executive Officer, Dr. Jakob Dupont, Executive Vice President and Global Head of Research and Development, Utpal Koppikar, Chief Financial Officer, Joe Newell, Chief Operations Officer, Dr. AJ Joshi, Chief Medical Officer, and Kristin Yarema, Chief Commercial Officer. We will begin with prepared comments from Pascal and Jakob, then open the call up for your questions.
We would like to remind listeners that during the call, the company's management will be making forward-looking statements. Actual results could differ materially from those stated or implied by our forward-looking statements due to risks and uncertainties associated with the company's business. These forward-looking statements are qualified in their entirety by the cautionary statements contained in today's press release and the company's SEC filings. These statements are made as of today's date, and the company undertakes no obligation to update these statements. Now I'd like to turn the call over to Pascal. Pascal?
Thank you, Eric, and thank you all for joining us this afternoon. As we know, we're all living and operating day to day amid a global pandemic never seen before in our lifetimes. Yet, at the same time, we at Atara remain committed to serving the patient in need and delivering expectations. Our mission indeed is to improve patient lives, and we are focused on bringing transformative therapies to those in need with even stronger commitment and resiliency. To date, we have seen a relatively limited impact of COVID-19 pandemic on our business. We have worked with our clinical trial sites to implement remote study visits, leverage telemedicine, home healthcare, and other methods to ensure continuity of care for patients and to preserve key endpoint data.
From a supply chain perspective, we continue to deliver product to patients from our inventory on time, which is a clear advantage of such off-the-shelf allogeneic EBV T-cells. Most importantly, we remain on track to initiate a BLA submission for tab-cel for patients with EBV positive PTLD by the end of 2020, with more details to follow in this call. The COVID-19 pandemic is continuously evolving. Going forward, we will closely monitor the situation and continue to assess its potential impact on our business and operations, including the timing and execution of clinical and pre-clinical studies. During the second quarter of 2020, we continued to make tremendous progress in delivering on our strategic priorities, tab-cel, ATA188 in multiple sclerosis, and our emerging CAR T portfolio. Starting with tab-cel, as I mentioned, we remain on track to initiate the BLA submission by the end of the year.
As a next step, we will conduct an interim analysis of the phase III study in the third quarter of 2020 and then discuss the totality of tab-cel data with the FDA in a pre-BLA meeting, after which we expect to initiate the BLA submission if the FDA is supportive. We believe that tab-cel has the potential to transform the treatment of EBV-positive PTLD and offers a compelling value proposition for patients and, very importantly, healthcare systems. As a reminder, relapse refractory EBV-positive PTLD is an aggressive, often deadly cancer with no approved therapy, and median survival in the HCT and SOT populations is only 1.7 and 3.3 months respectively. With tab-cel to date, we have seen a high and durable treatment effect with few treatment-related serious adverse events.
We expect to be able to deliver tab-cel to patients in need within three days from inventory and with a low burden of administration on the patients and treatment centers. If confirmed through a pivotal study, such a compelling value proposition could lead to significant business potential for tab-cel planned first indication. In terms of potential label expansion for tab-cel, we remain on track to initiate enrollment in the second half of 2020 in a phase II multi-cohort study with the goal of expanding the tab-cel label in PTLD and closely related diseases. We will focus on extending further into immunodeficiency-associated lymphoproliferative disease, or IA-LPDs. Given the commonality of the EBV-driven mechanism of disease in immunocompromised patients, high unmet medical need, and positive clinical data to date with tab-cel.
We are very excited about this potential opportunity for tab-cel, as this population represents altogether an additional few thousand patients with serious and addressable EBV-driven disease in the U.S. alone. To maximize tab-cel business potential, our near-term focus will be the successful initiation and fast enrollment of this multi-cohort phase II study on top of the planned BLA initiation in EBV positive PTLD by the end of this year. Moving on to ATA188, or EBV T-cell immunotherapy for multiple sclerosis. We strongly believe in the potential for ATA188 to become a transformative therapy, improving lives of MS patients. There remains a significant unmet need, in particular for progressive MS patients, with approximately one million patients living with such a progressive form of the disease.
Patients and caregivers are in need of new approaches with novel mechanism of action, in order to truly improve clinical outcomes and reduce disability. We believe ATA188 could have the potential to be such a therapy, creating tremendous value for patients, healthcare systems, and our shareholders. Beyond tab-cel and ATA188, we're also creating potential value for an exciting portfolio of innovative and differentiated allogeneic CAR T programs. These are based on our EBV T-cell platform and our ability to leverage new innovative technologies like 1XX and PD-1 DNR, licensed from Memorial Sloan Kettering, to improve efficacy, persistence, and durability of response, and to tackle both hematologic and solid tumors. We believe we are strongly positioned to provide patients with meaningful clinical benefit and create significant value.
With that in hand, I am excited to report that our collaborators at MSK have recently submitted an IND application to the FDA for next generation mesothelin-targeted autologous CAR T immunotherapy, ATA2271. We also continue to advance on our off-the-shelf allogeneic T-cell immunotherapy manufacturing platform. We are completing the manufacturing process validation activities for tab-cel while building inventory according to our commercial product supply strategy. Our EBV T-cell manufacturing platform continues to evolve and scale up at our wholly owned facility in Thousand Oaks, California. We have generated data confirming the use of stirred tank perfusion bioreactors to improve yield. Importantly, these data confirm that ATA188 can be manufactured in such stirred tank perfusion bioreactors with the potential to produce up to 40,000 doses per one donor leukapheresis.
Our scale-up manufacturing technology is a key enabler to deliver biologic-like cost of goods manufactured and will be leveraged across our portfolio, including for allogeneic CAR T programs. Now on to our financial results. We ended the second quarter of 2020 with $347.7 million in cash equivalents, and short-term investment. This is an increase from the prior quarter and reflects aggregate net proceed of $189.3 million from our recent public offering, including the full exercise of the option to purchase additional shares by the underwriters. Cash used from operating activity was $56.6 million for the second quarter of 2020 as compared to $54.6 million for the same period in 2019. We believe that our cash equivalents, and short-term investment as of June 30, 2020, are sufficient to fund planned operation into 2022.
In the second quarter, we also successfully onboarded two well-known scientific leaders in the field of cell and gene therapy. Dr. Jakob Dupont was named Global Head of R&D. Dr. Maria Grazia Roncarolo was appointed to the Board of Directors. Both have deep and diverse expertise in cell and gene therapies. I am delighted to welcome them to our team. In summary, I am extremely proud of how Atara's team members are continuing to make excellent progress against our key objectives. As a company, we remain committed to our mission. I want to personally thank all of our employees, contractors, collaborators, and of course, the patients we seek to serve, for all they do. I hope that everyone on this call today is staying safe and healthy, and I look forward to sharing our progress with you in the weeks and months ahead.
I will now turn the call over to our new Head of Research and Development, Dr. Jakob Dupont, to review further detail of our program. Jakob?
Thanks, Pascal, good afternoon, everyone. I'm excited to be part of the Atara team and to provide an update on our innovative portfolio of programs. As Pascal mentioned, we continue to advance tab-cel in phase III for PTLD, for which we have obtained breakthrough therapy designation in the U.S. and PRIME designation in Europe. This quarter, we have made significant progress in working with our existing clinical trial sites to enroll and treat new patients in our pivotal study. We've opened several new sites in Europe, notably in Spain, Austria, and Belgium. As a result of the hard work of Atara staff, with the cooperation of our partners at our clinical sites, we are on track to conduct the interim analysis of our phase III trial in PTLD in the third quarter of this year.
Following the interim analysis, we intend to meet with the FDA at a pre-BLA meeting in the fourth quarter of this year to discuss the totality of the data, and if the FDA is supportive, we plan to initiate the BLA by the end of this year. As a reminder, in Europe, we are in active discussions with the Paediatric Committee of the European Medicines Agency regarding a pediatric investigational plan, or PIP. Following discussions with the PRIME team, and after EMA approval of the PIP, we plan to submit an EU market authorization application for patients with EBV-positive PTLD in 2021. Looking ahead, we are on track to initiate enrollment in the phase III multi-Cohort study in the second half of this year and are eager to study tab-cel in these patient populations with such high unmet need.
We're exploring six populations in the multi-Cohort study with a focus on extending further into immunodeficiency-associated lymphoproliferative diseases, otherwise known as IA-LPDs. In particular, this study will evaluate both treatment-naive and previously treated patients in four patient populations with IA-LPDs, including two Cohorts addressing frontline EBV-positive PTLD patients with significant unmet need. An additional two Cohorts addressing EBV-positive LPDs arising out of primary or acquired immunodeficiencies will also be studied and represent an additional few thousand patients with addressable EBV-driven diseases in the U.S. alone. We expect the first Cohorts to enroll in approximately two years, with data expected in 2023. In addition, we believe there is the potential to file either by Cohort or for a tumor-agnostic designation.
As a reminder, previously reported clinical data from other EBV-driven diseases at ASH in 2018 in frontline and second-line CNS PTLD and at ESMO 2018 in leiomyosarcoma suggests that tab-cel may provide clinical benefit for these patients. We've also seen relevant clinical data through our tab-cel expanded access program in AID-LPD and PID-LPD, and we will present these as an e-poster, which has already been accepted to the European Society of Medical Oncology meeting in a few weeks' time in Spain. Our phase I-B program of tab-cel in combination with pembrolizumab in nasopharyngeal cancer, or NPC, successfully achieved its safety endpoints in stable disease in a subset of patients. We will look to present these data at an upcoming appropriate forum.
Following a strategic review and prioritization of our tab-cel programs, we decided not to progress with the phase II portion of the study at this time, but instead to generate additional translational data from this NPC study to further inform our strategies for this patient population with an evolving medical need. Turning now to our existing program, ATA 188 for multiple sclerosis. As most of us know, multiple sclerosis patients remain underserved with the current treatment options, especially as their disease progresses. Sadly, a continued decline in their disease is expected in progressive MS. The current treatment options offer a modest efficacy benefit at best. They only delay progression by a few months and clearly do not alter the course of disease. We believe there's tremendous opportunity to develop a transformative therapy to help patients in need. We have seen early but encouraging data with ATA 188.
Recall we presented important phase I-A data for ATA188 at the EAN conference in May, where seven patients showed sustained disability improvement and three out of six patients showed SDI at six months that was confirmed at 12 months with our Cohort 3 dose. We are now re-treating patients in the phase I-A using the Cohort 3 dose in the open label extension of the study, and we expect to present preliminary OLE data in an appropriate forum in the second half of this year. In addition, we also expect to present 12-month clinical results for Cohort 4 in our phase I-A study in an appropriate forum in the second half of this year. In June, we enrolled our first patient in our double-blind, randomized, placebo-controlled study using the Cohort 3 dose.
This study is designed to evaluate the efficacy and safety of ATA188 in patients with progressive forms of multiple sclerosis. This is certainly an exciting time for this very innovative program. We look forward to continuing to share our clinical results in the future. We are also planning to discuss with the FDA the full data set from our phase I-A study to explore possible accelerated regulatory pathways. Moving on to our CAR T portfolio. As Pascal mentioned, we continue to make significant progress on all fronts, even in the midst of COVID-19. We are pleased to announce our collaborator at Memorial Sloan Kettering have recently submitted an IND application to the U.S. FDA for our next-generation mesothelin-targeted autologous CAR T immunotherapy that we call ATA2271.
This marks a significant milestone in the evolution of the program, and we look forward to initiating a phase I study in solid tumors with our collaborators in the very near future. As a reminder, ATA2271 is designed to improve efficacy, persistence, and durability of response using a novel 1XX CAR co-stimulatory domain and a cell-intrinsic checkpoint inhibition technology with a PD-1 dominant negative receptor. The 1XX technology was innovated by Dr. Michel Sadelain, and the ATA2271 program and PD-1 DNR technologies are led by Dr. Prasad Adusumilli at MSK. Data from IND-enabling studies of ATA2271 were presented at AACR in June of this year. This is the first application of the combination of 1XX CAR co-stimulatory domain and cell-intrinsic checkpoint inhibition technology with PD-1 DNR.
This construct is associated with less cell exhaustion, improvements in functional persistence, serial cell killing, and in vivo efficacy, which is maintained through multiple tumor rechallenges when compared to first generation CD28, CD3ζ-based mesothelin CAR. At Atara, we are also making progress through IND-enabling studies with our allogeneic mesothelin CAR T program, which we call ATA3271. This also utilizes the same 1XX and PD-1 DNR technologies leveraged by our differentiated EBV T-cell platform. We are also executing on preclinical IND-enabling studies of our off-the-shelf allogeneic CD19-targeted CAR T, which we call ATA3219. This program utilizes our next generation CAR T technologies and EBV T-cell platform. The ATA3219 is supported by the initial proof of principle from an academic off-the-shelf allogeneic EBV CD19 CAR T clinical study that was presented at the 2020 TCT meeting.
These data showed the longest median duration of response in advanced B-cell malignancies for an allogeneic CD19 CAR T of 26.9 months. This data gives us further conviction that our EBV T-cell platform has the potential to generate off-the-shelf allogeneic CAR Ts with high response rates, durability, and low risk of toxicity. We have seen the EBV T-cells offer numerous advantages as the basis of our allogeneic platform, as they are potent cell killers that specifically target disease cells, are safe, traffic to the sites of disease, expand and persist in the patient. Most notably, we believe that ATA3219 has the potential to be a best-in-class off-the-shelf allogeneic CD19 CAR T therapy utilizing the next generation 1XX CAR T co-stimulatory domain and our EBV T-cell platform. As I noted, preclinical studies are underway, and we now expect to file an IND in 2021.
Finally, I would also like to extend our sincere thanks to our staff, collaborators, patients, and caregivers. We've accomplished much in this quarter thanks to you, and I look forward to providing updates on our continued progress in the near future. I will now turn the call back to the operator to begin the QA portion of the call. Operator?
As a reminder, to ask a question, you will need to press star one on your telephone. To withdraw your question, press the pound key. Please stand by while we compile the Q&A roster. Our first question comes from the line of John Newman from Canaccord. Your line is now open. Pardon me, John. Please check your line is now open. John Newman from Canaccord, please check your mute button.
Gigi, let's take the next call, and we'll see if John can get back in the queue, please.
Okay. Our next question comes from the line of Salim Syed from Mizuho. Your line is now open.
Great. Thanks so much for the color, guys. A few from me on multiple sclerosis, if I can, on ATA188. One, I believe the deadline to submit the late breaking abstract for ACTRIMS is August 13th. Pascal or AJ or Jakob, can you just confirm if you've submitted the abstract already, or if not, if you plan on doing it by that deadline? Number two, on the Cohort 4 data that we're going to get later this year. I was curious what your thinking is around moving to a Cohort 4 dose for the randomized portion. What's your criteria versus Cohort 3? If it's equivalent but marginally better, or you think you're going to move to that Cohort 4 dose or stay at Cohort 3. How are you thinking about that?
Lastly, on the OLE, can you just give us a little bit more color about how many patients we can expect to see and from which of the Cohorts are those patients coming from? Thank you.
Thank you, Salim. AJ, do you want to answer these?
Sure. Salim, I think at this point, we're going to not be specific about where we're planning on presenting these data. We are going to reaffirm that we will present the data in the second half of this year. In terms of the Cohort four dose and what does that look like, what good would look like there for us, was that your question? I apologize if you can repeat that.
Yeah, that was basically the question. Like, what is good?
Yeah.
What's the criteria you have in mind to actually use that as the dose going forward versus sticking with Cohort 3?
Sure. No, it's a good question. Obviously, we want to see safety. Certainly, what we've seen in the previous Cohorts is when we have sustained stability, we continue to see that. We'd certainly want to see that. Beyond that, we have to see the whole data set. We've talked before a little bit about stable disease is really transformational here, in addition to sustained disability improvement. We'd be looking at all those factors and put that all together to decide whether we want to add the Cohort 4 dose into the study. As you recall, our adaptive design lets us do that right away, so it doesn't really slow the study down in any way, shape, or form.
Okay.
When you think about the open-label extension data, right now we're not in a position to comment on exact numbers that we're going to have available when we talk about it. I think a way to look at it is that remember when we picked the Cohort 3 dose as the right dose to move forward, then we really opened it up to all the patients in the prior Cohorts who were able to move into open-label extension. As you might imagine, a lot of the Cohort 3 patients, because they were so active right there in the study, were the most rapid patients to roll over into it.
We are seeing patients from across all four Cohorts move on into the open-label extension, just not able to comment now on which Cohorts we'd be able to present at the right forum in the second half of the year.
Okay. The Cohort 3 patients were the ones that rolled over first, it's possible we can get 15 months data for Cohort 3?
You'll definitely have, yeah, some patients from Cohort 3 in that population.
Okay. Got it.
Maybe one other point to make here is that, just so you know, for the OLE, we did roll patients into that Cohort 3 dose. Even if there are patients at the earlier Cohorts, at lower doses, they're now being treated in the OLE at the Cohort 3 dose.
Got it.
As I mentioned in my presentation.
Understood. Appreciate it.
Also, Salim, to add that at the time we present the Cohort for 12 months data, we should be able to clarify whether we believe that these data justify the need to add these dose to the RCT or not. Be ready for that at the time.
Got it. Thanks, Pascal. Appreciate the call, you guys. Thank you.
Thank you. Our next question comes from the line of Benjamin Burnett from Stifel. Your line is now open.
Hey, thank you so much. I appreciate you taking the questions. I guess just a question on tab-cel and PTLD, I guess since your last update at ASH last year. Have you enrolled any new patients into that EAP, and when will we next see an update from that study?
Thank you, Ben. Jakob, do you want to take that question?
Certainly. We're obviously focused on the pivotal study, the 302 study, and to continue to get that enrollment. As you heard, we've achieved the sample size. It now allows us to initiate the interim analysis, which is great. We do continue to see interest in the EAP and the SPU programs as well. Obviously, we would prefer to divert patients to the pivotal study so that we can achieve as much enrollment as possible. As Pascal mentioned, these are quite sick patients, where there can be times when the EAP or the SPU is a better solution for those patients in urgent need.
Clearly, Ben, the next time you can expect data on tab-cel is in September at ESMO, where, as Jakob has said, we have an e-poster accepted that is going to present data with tab-cel from the EAP in this new patient population, the exciting new patient population of PID and AID-LPDs.
Got it. Okay. That's very helpful. Maybe just a follow-up question maybe also for Dr. Dupont. One thing we've heard about is just discussions around the logistics of running a second-line PTLD study, some of the challenges associated with enrolling such a rapidly progressing disease. I guess, thinking about the multi-Cohort IA-LPD study, how does second-line PTLD, in terms of disease severity and time sensitivity for treatment, compare to frontline PTLD and some of these other EBV positive disorders?
Maybe I'll start. We can have AJ add some additional color on the multi-cohort study. We do have six distinct patient populations that are included in the multi-cohort trial. I think there is definitely different tempos of disease here. You think about the AID, AIDS associated lymphoproliferative disorder, or the pediatric immunodeficiency patients, or the primary ones, I should say. These are populations where we're zeroing in on sites that have these specialty clinics, for sure. I think it is a more prevalent couple of disease states as we articulated. Just focusing on these patients, we think we can add some thousands of additional patients that we think does represent a good addition to the opportunity for tab-cel. There are going to be other indications of the six populations that include leiomyosarcoma, which may be less rapidly growing.
Each patient's tumor is a bit different in this regard, but you can think of some leiomyosarcomas that are a bit more indolent, where the urgency's not quite as great in terms of treatment. I think there's going to be particulars for each of these six populations, but they're certainly all very high unmet need, and some of them do obviously progress rapidly. The CNS-PTLD, for example, that's quite a medical emergency. AJ, anything further that you want to add?
Yeah, maybe just two additional points, I guess. To Jakob's point, there is a high unmet medical need, particularly, for example, in the AID/PID setting, when you're in the refractory population, you have a pretty similar aggressive progression that you do with PTLD. That's a space you want to get in as rapidly as possible. When you think about the CNS-PTLD, whether it's first line or in the refractory setting, those patients also tend to progress rapidly, because if you think about the first line therapies, they don't really penetrate the CNS as well as you'd like. That's actually an area that may even be a sweet spot for tab cell. Again, even in that first line setting, you'll see CNS-PTLD progress rapidly. Certainly not as rapidly as when it's relapsed refractory, but you still have good rapid progression there.
Okay. That's all very helpful. Thanks very much.
Thank you. As a reminder, to ask a question, you will need to press star one on your telephone. To withdraw your question, press the pound key. Our next question comes from the line of Marc Frahm from Cowen and Company. Your line is now open.
Hi, thanks for taking my questions. I guess maybe to start off with just with the planned interim analysis and then the BLA meeting, can you review what your plans are for the disclosure strategy? One for the underlying data, but also just around will you plan on informing investors when the interim analysis has occurred, and likewise, when the BLA meeting is happening?
Yeah. Jakob, do you like to start and I'll add anything that is needed there.
Yeah, absolutely. Thanks for the question. As we've described, we have achieved the enrollment to activate the interim analysis, which is great news. As we also have disclosed, it is an analysis which is upcoming quite soon. In Q3 of this year, after we've had the appropriate follow-up of these patients. It's a near-term thing. We do plan to request a pre-BLA meeting to discuss the totality of the data, as I mentioned. This is going to be not only the data from the 302 pivotal study, but we've also been working very hard on some of the legacy tab-cel programs from Memorial Sloan Kettering phase II studies there. We've already mentioned the EAP and the SPU programs.
We really intend to consolidate the totality of this clinical data, which we think is quite substantial, and to present that to the FDA after, again, the interim analysis, which is here in Q3. Then, of course, this all would lead to a BLA submission before the end of the year. Again, that's pending a good outcome of that meeting with the FDA. I think I'll leave it to Pascal to comment on the disclosure aspect. We don't want to disclose too early from the perspective that we don't want to undermine the integrity of the ongoing study. Obviously, this is an interim analysis, but Pascal, if you want to lend color to the disclosures along the way.
Yeah. I think there are two aspects in terms of disclosure. In terms of the data themselves, we will seek guidance from the FDA during that pre-BLA meeting on the appropriate time to share such information to ensure the integrity of the ongoing trial. That's once we align with them, we can then clarify where we're going to communicate in terms of the appropriate congress, for example. Disclosure will be also led by the importance of material events there, and we believe that the initiation of the BLA is clearly a material event at which we plan to communicate. Hopefully, with this alignment with the FDA, we could not only communicate that we've initiated the BLA, but hopefully some top-line data.
Again, that will be based on having an alignment with the FDA because we want to make sure that we preserve the integrity of the ongoing trial.
Okay. Maybe to follow up on earlier discussion of the multi-cohort trial. You gave the guidance that you think kind of across these Cohorts, it's maybe a few thousand patients that you could potentially ultimately add to the label. Can you give us at least a qualitative level, kind of the rough breakdown between the Cohorts? Is one or two of those really the primary driver of that couple thousand patients and the ones that we should be most focused on in terms of the market opportunity?
I think that's a great question. Clearly the two Cohorts with PID and AID are the Cohorts with the most patients there. We have a slide 27 on the new deck that we just posted that gives you an idea of the funnel of patients there. There are about 170,000 patients with autoimmune disease and HIV, 35,000 with primary immune deficiency in the U.S. It's about 205,000 patient population at risk in the U.S. The disease incidence is low single-digit for AID-LPD and high single-digit with PID-LPD, and the EBV positive rate is about 30%-50% in AID-LPD and 30%-75% in PID-LPD. Altogether it leads to a few thousand first-line and second-line patients only in these two Cohorts.
The other Cohort of interest is of course, the first-line Cohort in PTLD. The first-line EBV positive PTLD that are patients where the current therapies are inappropriate and then the CNS both first line and second line. It will be much rarer disease like EBV positive sarcoma, including LMS and CAEBV. That's the kind of order of importance of the potential number of patients. The first two are really the one that have the most patients, and that's why this is also priority in terms of enrollment and speed of enrollment once we start to initiate that study.
Okay, great. Thank you very much.
By the way, not only are we going to present data on these two particular Cohorts in September at ESMO, but the reason we are focusing on these is really that the disease itself is very similar to what we see in PTLD. It's a very nice possible label expansion from our point of view to address a real important medical need in a population of a few thousand patients in a disease that is very similar to the one for which we have a large set of data already in PTLD. That's also very positive for us to really focus our allocation of resources into this particular phase II medical study, specifically in this Cohort with high number of patients and important medical need.
Thank you. Our next question comes from the line of John Newman from Canaccord. Your line is now open. John Newman from Canaccord, please check your mute button. Your line is now open. Pardon me, John Newman from Canaccord, your line is now open.
Operator, seems like John's having some technical difficulties.
Oh, hey guys.
We'll pick this up with him after. Oh, there's John. Great.
This is John. I'm sorry, guys. Sorry about that. Thanks for taking the question. The question I had is just if you could talk a little bit about the longer-term view for tab-cel. I know that we're all very focused on the interim analysis, and that makes sense. That's a material event for the company. You are starting to run a study where you're looking at other EBV-positive malignancies, and I just wondered if you could talk about the longer-term opportunity here, because it's one thing to talk about EBV-positive PTLD, but it's interesting to start to think about all these other areas. I just wondered if you could talk a little bit about that opportunity. Thanks.
Yeah. Maybe I start and then AJ, you can add anything specific on the way we see that medical study. From an opportunity point of view, we think it's a great opportunity due to the commonality of this EBV-driven mechanism of disease in immunocompromised patients due to high unmet medical need. This body of positive clinical data today that we have already from EAP and SPUs, we know from this early data that the therapy seems to be working in these patients, and it's certainly safe there. We have that as a very clear opportunity to develop the potential of tab-cel. This should not take too long because as we said, we believe that by 2023 we should have data available in at least the first Cohorts, the one that are the most important one there.
Now from a regulatory point of view, maybe AJ want to comment of the possibility that we have either to have specific Cohort, sBLA type of indication or tumor-agnostic label. AJ, do you want to comment on that?
Yeah, sure. As Pascal mentioned, we would expect the larger Cohorts, the AID and PID to enroll more rapidly than some of the others. As we start looking at that common mechanism and you look at the six different Cohorts that we have, several of them have immunodeficiency associated, and they're driven by EBV. When you look at it from that perspective, it's certainly possible that the data that we generate off of AID, PID as well as whatever data we have off of the additional Cohorts would enable a tumor-agnostic label. When you think about adding that information from the multi-cohort to the information we'll already have on PTLD. There's certainly good possibility for that as well, and we'll of course assess that when we get close to that 2023 timeframe that Pascal mentioned.
Okay, great. One additional question. Not sure if you've mentioned this earlier on the call, can you talk about plans going forward in terms of when you might put the EBV CAR T against CD19 into the clinic that uses your 1XX costim domain? I'm not sure if you've given timing on that as of yet. Thanks.
Yeah. This is Jakob. I can mention that. As we've noted, we are in the midst of the IND-enabling studies currently at Atara, and we have disclosed that we are heading towards an IND filing in 2021. Work is progressing well in that regard.
Okay, great. Thank you.
Thank you. Our next question comes from the line of Yigal Nochomovitz from Citi. Your line is now open.
Hi, this is Samantha for Yigal. Thanks very much for taking our questions. Two for me. I wanted to start with, can you expand more on your decision to focus on the additional EBV-positive cancers now versus back in 2018 when you first generated the data for ASH and ESMO presentations? What's different now versus then that makes it more attractive to pursue?
Maybe I can start, and, AJ, you might want to comment on that. I think clearly at the time, we had only presented a few data, one from the legacy data at ASH 2018 on the CNS PTLD. At ASH 2019, we presented efficacy data on PTLD, but safety data on 61 patients, as you remember, that included not only PTLD, but other disease. We have now this efficacy data on EAP, and this efficacy data extremely encouraging, and that's one of the reason we have accelerated our plan. We have moved ahead, and we are going to initiate that study very soon. It's really based on data, because it's very rare to be able to go directly into a phase II in the way we are planning to do so.
Again, there is a slide explaining the protocol on our new investor deck based on already existing clinical data that clearly is showing that there is some efficacy in a few patients and an acceptable safety as presented at ASH 2019. It's based on data that we want to accelerate. At the same time, we know that there is a significant population out there in need of an innovative therapy like tab-cel. There is a medical need. We have early data, encouraging data. That's why we accelerating there to make sure that we can hope for hopefully a solution for this patient. AJ, anything to add?
Yeah. Maybe just one additional point. If you take a look at the data that we presented earlier, that was pretty much on the LMS population and CNS PTLD population. Notice that we haven't presented data on AID/PID. That's coming in September. As we developed more and more data on AID/PID, as you've already heard, that is the largest opportunity for us. That's also part of the factor in accelerating this program because those data have supported moving the program forward much more rapidly.
Got it. That's helpful. Just follow up, I guess you maybe sort of answered this, but what is more attractive about these EBV, the IA-LPD versus what you saw in the nasopharyngeal cancer trial? I guess what factors would need to fall into place where you would consider pursuing nasopharyngeal cancer again?
Jakob, do you want to take that one?
Yes, certainly. Thank you for the question. With the AID and PID LPDs, I think AJ explained well the value proposition there and the opportunity with the new data that we've generated. Now with the NPC study, we did achieve our goals of understanding the safety and seeing some stable disease at that point. We really want to generate more translational data here from that particular trial because this is a co-administration of cell therapy with a checkpoint inhibitor. It is actually a very active area of scientific research in the field right now to understand, is it better to give a checkpoint inhibitor concomitantly with a cell therapy, or do you give the checkpoint inhibitor before the cell therapy or after? There is actually a lot of these interesting scientific questions that need to be answered.
From that perspective, we think the prudent thing to do here is actually to work with our partners at Merck, who are very engaged as well, to answer some of these translational questions so that we can build the proper study going forward. As mentioned here, the multi-cohort study is quite a straightforward experiment from the perspective these are all EBV-driven tumors we're treating with tab. We have excellent clinical data to this point. We think that's the right opportunity and the priority opportunity to focus on while we are working with our partners at Merck to really understand some of these aspects of co-administration and the best way to go about that.
We think it's important also as we were to answer these types of questions for the field in general, because we are just at the beginning of these clinical experiments combining a checkpoint inhibitor with a cell therapy as well.
Clearly we think that we can go faster to address an important medical need with a relatively large population of a few thousand patients in the U.S. with a multi-cohort, particularly the AID/PID Cohort there. We want to go fast. That's why we're focusing on that.
Got it. Understood. Thanks very much for taking the question.
Thank you.
Thank you. Thank you. Our next question comes from the line of Matt Phipps from William Blair. Your line is now open.
Hi there, Rob Andrew on for Matt Phipps here. Thanks very much for taking the question. Apologies if I'm repeating a prior question here as I switch between calls here this evening. Just maybe on the multi-Cohort study, looking forward to some additional data at ESMO. Perhaps, given the rarity of some of these diseases, can you talk about the ease or the strategy for kind of identifying the patients? Are they being treated by the same docs that are treating the PTLD population? Does that mean that the enrollment centers for the upcoming study are likely to be the same? How common is testing for EBV positivity in these populations? Is that standard, or is that something that's not standardized there?
Yeah. Thank you, Rob, for your question. AJ, you want to answer this one?
Sure. Maybe just as a couple of points, we talked about the testing. The testing is actually fairly routine. It's not done as aggressively as it is in the transplant population because you literally track that from the moment that transplant is done. You want to make sure that their EBV viral load isn't going up. In these populations, when they develop tumors, it's fairly standard to check for EBV, so there's really not much of a concern in terms of a diagnostic there. The second piece you were asking about is where do these patients show up? Certainly when you're taking a look at the larger transplant centers, they almost all will have a dedicated group that's looking at these LPDs for AID/PID. Not that there's 100% overlap, but there's significant overlap at the large centers with PTLD as well as AID/PID.
There will be some separate centers, but there's a larger group that do overlap. You also get the other populations, the LMS population, and we have the CA-EBV population, a few others, that show up at those centers. I would say there's significant overlap. We'll have some kind of unique centers that we'll also add in. From an operational perspective, there are advantages to that commonality of occurrence.
Okay, great. That's helpful. Thank you. Maybe if I can just squeeze in a quick follow-up on the pre-BLA meeting prior to the BLA filing. Just assume you're not really envisaging any difficulties in getting this kind of thing organized with the FDA, just given the focus on COVID and kind of likelihood of a slew of vaccine data in the fall there.
Jakob?
Thank you, [William] for the question. Obviously, COVID-19 is a major concern at this point in the world as Pascal has alluded to as well. I think the very fortunate position that we're in at Atara with tabelecleucel is that we have a few designations, so that'll really have frequent and excellent engagements with the FDA. And similarly, in Europe, we have PRIME designation, which really allows us to have an excellent dialogue. And I do think that the agencies have really prioritized discussions for programs that have breakthrough therapy and PRIME designations. We've actually had very good engagement from the agency even during this period of COVID.
Great. Thanks very much.
Thank you. Our next question comes from the line of Michael DiFiore from Evercore ISI. Your line is now open.
Hi guys. Thanks so much for taking my question. There's a few from me. One question on ATA188 regarding the durability and non-responders to therapy. I was wondering if there's any developments or updated thinking about using an HLA restriction switch to rescue non-responders, and also perhaps patients who may lose response. Along those lines, is there a mechanism in the current randomized phase I, part two trial for this rescue? What's the FDA's views on allowing that to be employed in the context of a pivotal trial or any trial for that matter?
Yeah, AJ?
Sure. Part of the question there is what is a non-responder? For us, as we talked about this notion of transformational therapy, if you can halt progression or reverse progression, that's transformational. The vast majority of the patients so far really have maintained their disability status. It's really hard to identify who a non-responder is at this point. I wouldn't expect immediately to be able to provide information on that just because we don't have someone who I would officially say is a pure non-responder based on that definition.
That said, there's already built-in mechanisms that are part of the trial, both in the open label extension, that allow switch for any of those for anyone who is felt to be a non-responder. In terms of your question around how FDA feels about that concept of restriction switch is already built into our phase III tab-cel program, so they're very familiar with it and very comfortable with the concept. We're just simply applying that similarly to the 188 program. It's really more, we need more longer observation before we can get some of that experience on switch because we still haven't, in my mind, seen really much to be able to say we definitely need to switch somebody.
Great. No, that's helpful. Just a quick follow-up. Just wondering how we should think about the placebo response rate in the current phase I, Part 2 MS trial. We've seen from the MedDay experience how this could blow up in phase III. If you could just give us a refresher on what the typical placebo response rates are in the primary progressive population, that'd be helpful.
Sure. If you were to base it off the best study is, of course, the MedDay study because we're using a similar endpoint to what they did. Slightly different time points, quite similar. For them, one of their studies had a 0% sustained disability improvement rate for placebo, and the other study had about a 9.2%. We all think that's a pretty good benchmark for what we would expect in our study, somewhere between a 0% and 9% placebo rate. What's a little bit different from their study versus ours, which might argue for even a placebo rate on the lower end for our study, is that in their study, they did allow whatever medications that the patients were on, they were allowed to stay on, and the MedDay treatment was an add-on on top of that.
Versus our study, we're looking at pure placebo. The likelihood is that we'd be on the lower end of that placebo range that they saw between the 0% and 9%.
Great. Very helpful. Thank you.
Of course, that compares favorably to what we've seen so far in our phase I experience.
Got it. Thank you so much.
Thank you. Our next question comes from the line of Anupam Rama from J.P. Morgan. Your line is now open.
Hey, guys. This is Tessa on the call this evening for Anupam. Thanks for taking our question. Just two quick ones from me. We talked a bit about the ESMO update in the prepared remarks and in some of the earlier questions. Can you just give us a bit more granular on how you would define a win at the conference? My second question, a prior question alluded to this, but around the decision to discontinue development in NPC, what were the levers that went into making that decision? Was this efficacy driven at all, and can you discuss a bit further the translational work that you plan to do? Thanks so much.
Thank you. Thank you for your question. I mean, I'll start with the second one, ask Jakob before we talk about ESMO, I guess it's your question. On the NPC, just want to correct, we're not discontinuing the development. We're just not moving into the phase II as it was initially planned because we want to do this additional work to clarify what is the best path to develop and create some value there for the patient and for tab-cel there. We are still working on that with our collaborators at Merck. Jakob, do you want to comment further on what led to that decision?
Absolutely. As Pascal noted, we did actually achieve the goals of the phase I portion of the study. We saw very good safety results. We also saw stable disease, and we were able to combine the drugs successfully. As mentioned, we really wanted at this point, in terms of prioritization, to focus on the resources of Atara on indications where we felt that we could create a lot of rapid value. There's another aspect here with the evolving treatment landscape in nasopharyngeal cancer as well. With the uncertainties of the shift in the landscape and also wanting to understand this key scientific question of checkpoint inhibitor with cell therapy combination, we really wanted to do more translational work. That is an effort that we've undertaken at Atara, obviously working with colleagues at Merck as well.
We have a number of patient samples from the clinical trial where we're looking at the phenotypes of the cells before and after treatment with a cellular therapy, with a combination of the checkpoint inhibitor as well. We'll be able to do a very nice series of experiments both at Atara and then also with our collaborators at Merck as well. It really was not, as Pascal noted, a decision to discontinue the program. It was just to do more work and figure out how to do the right type of experiment in the future if we choose to do so.
In terms of resource allocation, we really need to invest where we can create value as rapidly as possible. As hopefully we explained in the call and in answering questions, we believe that that opportunity in the multi-cohort study with various Cohort, particularly those in immunocompromised patients with lymphoproliferative disorders that are very similar to PTLD, and for which we have a very clear path to potential regulatory submission in a very rapid way. This is where we believe we should invest right now while we continue to work with Merck on clarifying a path for NPC. Your question, ESMO, I guess, is around what type of data we're going to present there. AJ, do you want to answer that one?
Yeah. You're asking what we would consider good for that population. I think maybe a way to look at this is when you think about the non-PTLD data that we've publicly presented to date, we've generally looked at any routine, I mean, one population was 17% response rate, and another population was 20% response rate. These were all settings that were relapsed refractory. These are fairly sick populations with really no other treatment alternative. The AID/PID population we'll be presenting on is similar to that group, where you're going to have that same relapsed refractory setting. Data like that or better would be a real win here because of the aggressiveness of the disease in these patients once you fail existing therapy.
Note that is a little bit different than what we're going to study in the multi-cohort, because we will study both the relapsed refractory setting as well as the first-line setting.
Great. Thank you for the clarification and the color, guys. Appreciate it.
Thank you.
Thank you.
Thank you. Our next question comes from the line of Maury Raycroft from Jefferies. Your line is now open.
Hi, this is Kevin for Maury tonight. I just wanted to circle back briefly to the tab-cel EBV positive PTLD readout. A quick question just about, given the sample size is smaller than what you had initially planned, do you think that affects your ability at all to hit the desired response rate? A quick follow-up on the pre-BLA meeting with the FDA. I know you talked about what's going into that data package. Can you talk about briefly what the FDA's expectations might be in terms of that data?
Jakob?
Yeah, absolutely. Thanks, Kevin, for the question. In terms of sample size, I think we're actually operating here according to plan because the study does actually have a pre-specified interim analysis, which is actually what we're doing now. That's part of the study design, actually. We are generating that data, as I mentioned, here in Q3, and we're also providing data from other historical sources. We've spoken about the Memorial Sloan Kettering phase II studies in the past in PTLD, also the EAP and the single patient use or the SPU as well. I think there's a lot of informative data there that certainly the FDA wants to see, because it does provide insights into the overall safety and efficacy of the clinical benefit equation for Tabcel in this high unmet need.
Again, I think we have a lot of rich information to provide, and we are bringing that together actively now at Atara. I don't think we'll comment on the specifics of the data package here that we will supply. In terms of likelihood of success, I just wanted to speak to that directly. Again, I think that the likelihood of success here is really very much according to plan, because again, the interim analysis was built into the study design as planned.
In terms of the FDA expectations, obviously, we have breakthrough therapy designation for the program, which was established a little while ago, which was based on the data that we had generated in the past, which includes those response rates in PTLD in the range of 50% to 80%, depending on which patients you're looking at across the diversity of our clinical experiment thus far. We have also publicly disclosed the 37% response rate as a target here, obviously with some durability information as well. I think that response rate is certainly one that we've discussed with the agency as well. I think things are tracking very well from our perspective.
As I mentioned, the interim analysis is coming up quite shortly and we're also making good progress bringing in the historical data and making sure that's in a good format for discussion with the agency as well.
Great. That's helpful. Thank you.
Sure.
Thank you. This concludes our question and answer session for today. Thank you for joining the Atara Biotherapeutics second quarter 2020 financial results conference call. You may now disconnect.