Atara Biotherapeutics Inc (ATRA) 2021 Q2 法說會逐字稿

Good afternoon, everyone. Thank you for standing by, and welcome to the Atara Biotherapeutics' Second Quarter 2021 Financial Results Conference Call. (Operator Instructions) 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. Please go ahead, sir.

Thank you, operator. Good afternoon, everyone, and welcome to Atara's Second Quarter 2021 Results Conference Call. Earlier today, we issued a press release announcing our second quarter financial results and operational progress. This press release and an updated investor presentation are available in the Investors & Media section at atarabio.com.

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. 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. José Vidal, Head of GMP Quality and Process Sciences; Dr. AJ Joshi, Chief Medical Officer; and Dr. Kristin Yarema, Chief Commercial Officer. We will begin with prepared comments from Pascal and Jakob, then open up the call 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. We have completed a strong first half of 2021 and are making good progress on all 3 of our strategic priorities: tab-cel, ATA188 in multiple sclerosis and our next-generation allogeneic CAR T programs.

Supported by our breakthrough therapy designation, we have been having regular dialogue since January with the FDA. We recently conducted productive meetings with the review team at the FDA and gained alignment, clarity and actionable next steps in order to submit the tab-cel BLA.

First, we gained alignment with the FDA on the key methodology for evaluating comparability between tab-cel clinical and commercial products. In addition, the FDA asked for, and we will provide to them, data on substantially all tab-cel lots made to date by Atara. We believe this should clear the way for the FDA to make a determination at an upcoming Type B CMC meeting regarding our expanded data package supporting comparability between the product used in the pivotal clinical study and the intended commercial product.

Next, the FDA decided it cannot make a determination of comparability between the non-pivotal product and the pivotal clinical study product, and clinical data from the historical non-pivotal study will not be pooled with the pivotal ALLELE study data. Rather, we intend to present this data in parallel as part of the BLA submission.

Importantly, at this time, the FDA has made no new request for Atara to conduct additional clinical studies, develop new assays or conduct new manufacturing of lots. We are confident that we will have a robust data package to demonstrate comparability to the FDA between pivotal and commercial process versions of tab-cel, and we are encouraged by the ongoing interactions as we work towards finalizing our CMC module 3 for the BLA submission.

Turning to the pivotal ALLELE study. We have recently successfully completed the analysis of the Q2 data cut previously requested by the FDA. Top line data shows strong objective response rate in line with prior results and a consistent safety profile with no new safety signals.

In addition, we now have new robust durability data as well. This data from our pivotal study are impressive for such an ultra-rare and unmet need condition like relapsed/refractory PTLD, where patients have no treatment options. The latest data cut will be discussed with the FDA for the Type B clinical meeting and is what we plan to use as the basis of both the BLA and the MAA submissions. As a reminder, we continue to plan to present these Phase III ALLELE data at an appropriate congress in Q4 2021.

Looking ahead, we now have clarity around the required next steps for resolution and submission of the BLA for tab-cel. Although this has taken some time, as Atara is a trailblazer for allogeneic cell therapy in the world, and is paving the way for this first ever allogeneic off-the-shelf T cell therapy to reach regulatory filings, we now expect to complete the BLA submission for tab-cel in Q1 2022.

Our investments in U.S. commercial readiness activities have been shifted to this new timing, gating our spending versus what was previously anticipated, as we now plan for tab-cel approval and U.S. launch in the second half of 2022.

As we continue to prepare for commercial launch, I'm very pleased to announce that cell therapy and oncology commercialization veteran, Ameet Mallik was appointed to the Board of Directors. Ameet brings to Atara's Board a wealth of experience with U.S. payers, access and reimbursement strategies and launches of innovative oncology therapy, including CAR Ts.

Now turning to Europe, where we're also making excellent progress. We recently had successful pre-submission as well as co-rapporteur and rapporteur meeting with EMA and cleared all compliance checks. So we can now move forward to submit the EU market authorization application for patients with EBV+ PTLD in November of 2021.

In parallel, there is a strong level of interest from ex-U. S. partners, and our partnering discussions are progressing very well, in line with our expectation to secure a partner for Europe by Q4 2021. Meanwhile, we are also actively enrolling patients in our tab-cel Phase II multi-cohort study in other EBV-driven cancers. The 6 study populations, of which the largest to our EBV+ AID-LPD and EBV+ PID-LPD, may support meaningful label expansion beyond second-line PTLD.

Turning now to ATA188, our transformative product candidate for patients with multiple sclerosis. I'm very excited to announce that important new data will be presented in October at ECTRIMS. These will include new magnetization transfer ratio imaging data, an imaging biomarker linked with myelination in addition to the 2-year clinical data update from the Phase I open-label extension study. We are excited to present this new data, and Jakob will have more to say in a moment.

Meanwhile, we continue to make progress in enrolling the Phase II randomized double-blind, placebo-controlled study, or EMBOLD study. We are on track to conduct an interim analysis for this study in the first half of 2022, including efficacy and safety in patients with progressive forms of MS. Following this interim analysis, we expect to have further discussion with the FDA regarding potential study adjustment for pivotal intent. These are important discussions from both a regulatory and strategic perspective for the program and could provide optionality on how we advance development.

Momentum, meanwhile, continues to build in the community, reinforcing the association between EBV, Epstein-Barr virus, and MS and the transformative potential of ATA188 for MS patients. This was confirmed by a recent survey amongst top U.S. neurologists.

We also continue to see significant interest from a number of large companies regarding a potential collaboration involving ATA188, as we truly have a unique asset, the only investigational therapy in a randomized controlled trial in progressive MS with disability improvement as the primary endpoint.

Moving to our CAR T portfolio and, first, our mesothelin franchise program, ATA2271 and ATA3271. This mesothelin-targeted CAR T product are benefiting from our global strategic collaboration with Bayer, which is off to a strong start. For ATA2271, our autologous mesothelin CAR T program, we expect to present the first update on Phase I data for patients with advanced mesothelioma in Q4 2021.

The off-the-shelf allogeneic version of this mesothelin CAR T program, ATA3271, using a PD-1-dominant negative receptor and 1XX CAR co-stimulatory signaling domain, built on our EBV T cell platform, is currently in IND-enabling studies and is progressing well. We expect Bayer to submit an IND in the second half of 2022 and subsequently lead clinical development and commercialization activities.

Turning to ATA3219, or allogeneic CD19-targeted CAR T for patients with B-cell malignancies, we can submit an IND in Q1 2022, in line with our strategic goal to develop this asset as a best-in-class for B-cell malignancies.

Moving to our financials. With regard to our cash positions and runway, our cash burn in Q2 was $61.8 million, and we ended the second quarter of 2021 with $373.4 million in cash. With this cash balance and our updated and well-controlled planned expense profile, we believe we are sufficiently funded into 2023.

As we turn ahead into the third quarter of 2021, I am delighted to see how far Atara has come from this time a year ago. Each and every one of our staff has delivered on our goal of saving and improving lives of patients with serious disease. On a daily basis, we partner closely with clinical study sites with our manufacturing and logistic partners and our collaborators in order to ensure patients could continue to access our therapies.

With the hard work of the Atara team, we are on a clear path to file our tab-cel regulatory submissions and bring this life-saving medicine to patients in need. I will now turn the call over to Jakob. Jakob?

Thank you, Pascal. I am pleased to provide further details on the progress we made during the second quarter in advancing our 3 strategic priorities. Starting with tab-cel, we have aligned with the FDA on several key aspects required for BLA submission.

Regarding comparability of tab-cel clinical and commercial product, we reached alignment on methodologies for evaluating these 2 sets of products. As requested by FDA, we are providing data on nearly all pivotal and commercial tab-cel lots manufactured to date. We believe FDA should agree on our comparability data package when we discuss these new data at an upcoming Type B CMC meeting.

This belief is directly related to the consistent and tightened process performance data that was generated from the pivotal and commercial production campaigns as well as the fact that process changes between pivotal and commercial were minimal and mainly related to the commercial GMP compliance of the EBV viral reagent used in manufacturing.

With regard to comparability of historical non-pivotal tab-cel product versus pivotal clinical study product, the agency recently clarified that they would like to see comprehensive analytical data on most historical lots. Therefore, we have agreed with the FDA that comparability cannot be established because we do not have product available for some of the lots manufactured by MSK in the past. This important resolution of comparability means that clinical data generated using historical non-pivotal product will not be pooled with pivotal clinical data.

Importantly, this decision is consistent with the prior FDA decision to evaluate in parallel the data of a CAR T product from an academic center's non-pivotal product versus the industry partner's pivotal clinical study product, for which ultimately the FDA granted marketing approval.

Turning to the pivotal ALLELE study. We have recently successfully completed the analysis of the Q2 data cut requested by the FDA for the Phase III ALLELE pivotal study. Top line data evaluated through independent oncologic and radiographic assessment shows strong ORR in line with prior results with half the patients responding and a safety profile consistent with previously published data with no new safety signals.

Importantly, this new data cut demonstrates new robust durability of response. This latest data cut is what we plan to use as the basis for both the BLA and the MAA submissions, while also providing additional supportive data from our historical non-pivotal studies, expanded access and compassionate use study patients.

To summarize next steps, we anticipate speaking with the FDA in a Type B CMC meeting to discuss our expanded data package on comparability between pivotal clinical study product and commercial product as well as a Type B clinical meeting to discuss the latest data cut from the ALLELE study now with robust durability of response data requested by the agency that will form the basis of the BLA filing. Requests to FDA for these meetings have already been made, and pending alignment, we could then file the BLA in the first quarter of 2022.

As Pascal mentioned, we've also made excellent progress in Europe. Tab-cel's prime and orphan drug designation with EMA has enabled regular engagements with the agency and our PIP compliance checks have been successfully cleared. Our recent successful pre-submission as well as co-rapporteur and rapporteur meetings means that we have cleared the path for the MAA submission in the EU. Therefore, we can submit the market authorization application for patients with EBV+ PTLD in November of 2021.

Taking a step back and thinking about PTLD patients in dire need of treatment options, we recently joined the Rare Disease Company Coalition alongside other rare disease leaders and constituents to engage in conversation with policymakers on the need for speed and access for life-changing therapies. Atara is committed to leading the path forward for transformational therapies for rare disease patients.

Moving now to ATA188, our product candidate for progressive multiple sclerosis. We are excited and look forward to presenting at ECTRIMS in October long-term 2-year clinical data from the Phase I open-label extension and new translational data from the Phase I study of ATA188 in progressive MS. Included will be new imaging biomarker data considered to reflect the state of myelination in the CNS known as magnetization transfer ratio, or MTR.

With respect to MTR, decreased MTR in MS lesions may correlate with demyelination and axonal loss in MS patients, while increased MTR may correlate with remyelination. These data may provide key information on the mechanism of EDSS improvement in our ATA188 clinical data. We are excited to present these new data in October. We also plan to use MTR as a relevant imaging biomarker correlated with disability improvement in our ongoing Phase II EMBOLD study.

Turning now to our CAR T programs. In addition to Pascal's comments, I would also add that we are making excellent progress on our mesothelin franchise programs with our partner, Bayer. This partnership is helping to demonstrate the progress of the technical and manufacturing elements of our EBV T cell platform. We are delighted to leverage the capabilities of such an experienced company as Bayer and look forward to providing further updates later this year.

ATA3219, our allogeneic CAR T for patients with B-cell malignancies, is also advancing well and with -- we believe that this therapy could be a best-in-class treatment in B-cell malignancies as there is still significant unmet need despite increased therapeutic options.

Finally, I'd like to extend a warm welcome to our newest leadership team member, Chief Scientific Officer, Dr. Cokey Nguyen. Cokey comes to us most frequently, or most recently, from Fate and brings his deep experience in CAR T paired together with a strong conviction around the unique benefits of our EBV platform to drive our exciting CAR T cell franchise forward into the future.

I'll now turn the call back to the operator to begin the Q&A portion of the call. Operator?

(Operator Instructions) Our first question comes from the line of John Newman with Canaccord Genuity.

Congrats on the good progress here. So Jakob, you mentioned a submission has been made to request for a Type B meeting for the comparability data for tab-cel. I was curious if you know about when that might take place? And then on the clinical side, beyond the most recent data look for ALLELE that you've conducted, just curious if you think the agency will require any additional data looks in the future, maybe either with some additional patients for longer follow-up.

Thank you, John, for your question. Jakob, do you want to take the first one?

Yes. Thanks, Pascal, and thank you, John. So yes, we have submitted meeting requests for the Type B meetings both for CMC comparability and for the clinical discussion as well. Now per PDUFA time lines, we should hear back from the agency within 60 days of that request. So we believe that this meeting will occur within the next 2 months.

And the second question on clinical data beyond ALLELE?

Yes, absolutely. So we believe that this new analysis for ALLELE is strong enough to support a BLA filing. But of course, if the FDA wants updates specifically, such as safety with a subsequent 90-day safety cut, we can certainly do that. But we do believe that the current Q2 data cut for ALLELE is sufficient to support the BLA submission as well as the MAA application.

And as you know, we're also going to be providing historical non-pivotal data and EAP and SPU clinical data in the BLA and MAA filings in parallel, but not in a pooled fashion due to the outcome which we thought was quite favorable in terms of noncomparability between historical and pivotal material.

Does it answer your question, John?

Yes, it does.

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

Congrats on the progress. It does seem like the FDA is being pretty cautious on the types of BLA. I guess given that you can't pool and that you think the Q2 update on ALLELE is as far as you're going to need to go, what is the duration of response that you'll be able to claim on the pivotal data relative to what you could have claimed on the pooled data?

Separately, it seems like IND timelines for the allogeneic CAR T programs are going to be a little bit towards the back end of the prior guidance. I just wondered, what's the gating factor on those INDs going forward from here?

Thank you for your question. Do you want to take the first question, Jakob, please?

Yes, absolutely. So I would say that we've made great progress with the FDA in terms of understanding the comparability issues and then obviously also providing this Q2 data cut that the FDA requested from us in October of last year, specifically to provide durability data on the patients that had already enrolled.

Now the guidance that the FDA has provided to us, which they provide to other sponsors, is that they want to see durability of that response, which basically means that from the time that a response is detected, you want an additional 6 months of follow-up on those patients since the time of response.

So if you think about -- we got that guidance in October of last year. We let the data mature further, collected the data based on a Q2 data cut then provided it to our independent review facility for independent oncologic and radiographic response. It really fits those criteria of 6 months duration of response after that initial response is detected. And that's pretty standard request from the agency.

Yes. Another thing, the fact that we align with the agency on the durability of response we want to see, and we have this data now, makes us very confident in the strength of this data package that we'll present in the forthcoming Type B clinical meeting.

Now on your second question, it's just that we have refined our thinking on the different manufacturing timelines for this program and the development that is needed to file the IND. The thought we are doing on this platform as we progress on these specific programs, we, by the way, help the rest of the early pipeline. And we are leveraging our platform there. So there is no particular aspect there that is a particular challenge, apart from the fact that we have now fine-tuned the exact timing for the IND filing.

And for ATA3219, we'll be, of course, after our filing the IND well for 3271, will be Bayer filing the IND there. Now we're also trying in developing this IND package to make sure that we can optimize our chance of having 2 best-in-class platform for allogeneic CAR T.

And this is, we believe, where ATA3219, in particular, could have a significant potential advantage in optimizing characteristics of the cells to make sure that we can leverage the innate properties of EBV T cells together with 1XX as the co-stimulatory domain to really make something that could go to the clinic with the potential and the goal to be a best-in-class in B-cell malignancies. Does it answer your question, Jon?

Yes, absolutely.

Our next question comes from the line of Salim Syed with Mizuho Securities.

Great. Congrats on the progress. A couple from me, if I can, on ATA188. So Pascal, you sound pretty excited, and I know the press release even uses that word, exciting new imaging data.

So as much as you can say here about the MTR and whether that's actually -- refers to myelination patterns, are you seeing or do you think you're seeing remyelination with ATA188? I'm curious to get your thoughts on the FDA being able to use this as a biomarker for accelerated approval, just given everything we've seen with the accelerated approval around Alzheimer's?

Thank you, Salim. We are definitely excited, but we are not going to give you the data. That, you will have to wait for October. But AJ, do you want to comment on MTR and what we believe this particular set of data is very important? And what's our plan with the FDA in terms of how this could be used as a biomarker?

Yes. Thanks, Pascal. Hey, Salim. Yes, I think with the MTR data, you've heard that. It's pretty much the -- when you look at MRI, biomarkers looking at myelination, that's really the most used one in all the studies that you're looking at. And as you might imagine, it's been correlated with decline in EDSS, so a decline in disability. So if you have lower MTR, you actually have -- lower MTR means you have demyelination, and that means you have a decline in disability. So that correlation has been made.

What's interesting is no one's actually shown improvement because, as you know, no product has shown an improvement in disability in a progressive situation. But what is interesting is if you take a look at MTR in relapsing disease, so this is where you've got an active lesion and you use a therapy that works in inflammatory disease, you'll actively see MTR increase because you get remyelination once the inflammation comes down.

So you do see MTR increasing when you have remyelination. It's just never been shown in the progressive setting. So from that standpoint, what we're trying to do is we're trying to say, look, MTR is relatively established as a measure of myelination, both demyelination and re. And we're now trying to apply that to the study data that we have now. So obviously, we're looking forward to presenting the data coming in October.

And in terms of how you could leverage this going forward, it's really not been used as anything like a surrogate marker or anything like that to date. But again, a lot of that, we think, is just because there hasn't been a lot of good reason to take a look at disability improvement and MTR changes.

So certainly, we're going to very closely monitor MTR throughout the course of the EMBOLD study, and we're going to be talking to FDA, and we'll be including all of the MTR discussions in those conversations. But today, it's a little bit too early to say, yes, this is going to be an established biomarker. But from a scientific perspective and a clinical perspective, it is established within the scientific community right now.

Yes. And as AJ has said, it will be -- one of the endpoint will be following in the current randomized controlled trial. So not only we have data coming in October on the Phase I, but we'll have also data coming forward later on, on the Phase II study when we get access to this data.

So that's something of a plan in terms of leveraging this particular biomarker that has been used in a number of studies, but not yet correlated with improvement in disability, and that could be something very exciting.

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

Congrats on the progress. A couple on the comparability issue. You mentioned briefly in the prepared remarks what the differences are between the pivotal and commercial material. Could you go into a bit more detail at the significance of those differences?

And then secondarily, now that the methodologies have been clearly defined, can you talk a bit more about your confidence that the FDA will find the pivotal and commercial material comparable?

Now certainly, José, do you want to address the first question on the difference between pivotal and commercial material? And then Jakob, you can address the second question on the FDA, how we perceive the confidence that we have, that we have that data that we'll be giving them to decide positively on comparability? Jose?

Certainly, Pascal. Yes. The difference is the actual source and grade of the Epstein-Barr virus that we use in the manufacturing process. We switched from a clinical research grade producer cell line to produce the virus into a full GMP commercial-grade producer cell line, and we switched also the manufacturing place of the virus to our own facility from the previous CMO as the CMO had no capacity to supply commercial volumes.

We have done full characterization on that, and we are pretty confident that it's a minimal change, but that's the summary of the change between the pivotal and clinical material.

Thank you. And Jakob, on how do we see the data package for the FDA?

Absolutely. So I think one of the really important things, Phil, that we learned from the FDA as they're thinking evolved around tab-cel, which is the, as you know, the first allogeneic T cell product, which is going across for FDA approval. We've learned that they have this requirement now to see the data from all the lots that have been created in order for a determination of comparability to be made between pivotal material and commercial material.

That was the reason why we could not deem comparability between historical and pivotal because we simply didn't have some of the lots from Memorial Sloan Kettering. But what we do have are virtually all of the lots from pivotal and commercial so that we can do full comparability analyses.

So having the agency give us the lay of the land and what the requirements were in terms of sharing the totality of that data, that is something that is really accomplishable from our perspective, and having that clarity from the agency is really valuable. So that's why we put the Type B meeting request in, which again will occur within the next 60 days or so.

And we will put to them exactly that question of have we now secured this comparability with the full data package with the help of José and his full team in CMC manufacturing. And we believe that we're going to achieve this because we know what the rules of engagement are.

Yes. And we think also that the whole data set we have is really very robust due to the robustness of our manufacturing process performance and the minimal changes that we've made between pivotal and commercial process as José just explained. Does it answer your question?

Great. And one last question -- yes. Maybe just one last one. What's the rate limiting factor to the Q1 filing? Is that comparing -- is that completing the comparability analyses? Or is there something else that's gating?

Jakob?

Yes. So to provide these details -- so as mentioned, we want to have the Type B CMC meeting within 60 days to solidify the issue of comparability of pivotal to historical, so that will get taken care of. Then we have the Type B meeting for clinical, where we share the most recent data cut from ALLELE and we get the agency agreement on that. Now that hopefully is going to solve most of the issues.

Now there may be some more administrative issues that could get taken care of in a pre-BLA meeting. So our base case is have these 2 Type B meetings with the FDA and then, after that, have a pre-BLA meeting that leads to a Q1 completion of the BLA filing. Now there is an outside chance that if we secure all the issues in these 2 Type B meetings that we may be able to have a faster submission of the BLA. But frankly, our base case is to say we need to have these 2 Type B meetings then the pre-BLA meeting and then we complete the submission of the BLA.

And what makes us confident there is, again, the strength of the data. We know the data in terms of clinical data there from the ALLELE data cut in Q2, and they're very strong. We know the robustness of our process, and we have all the data needed to provide the FDA with substantially all the lots of the data on all the lots made by Atara. So in terms of delivering what the FDA is asking for, we feel very clear.

(Operator Instructions) Our next question comes from the line of Matt Phipps with William Blair.

I have a few. First, was it always a plan to have a Type B clinical meeting after the Q2 data cut? It just seems like that would kind of made it impossible to previously have hit your guidance for Q3 submission -- completing that submission regardless of, obviously, the CMC issues. So just wondering if that is something new because, again, it doesn't seem like that lines up with your previous guidance on time lines outside of, obviously, the CMC issues.

Okay. So maybe I answer the first question on the guidance and then you say that you asked another question. No, I think when we put the guidance on Q3, it was really based on the Type B CMC meeting that we had in Q2 and on the basis that, following that Type B CMC meeting, we could then move from a pre-BLA meeting and in the August time frame, based on the data cut and then go with that with the submission of the BLA by the end of the Q3. That was basically the guidance basis there.

Now what's happening is we have the 2 aspects now. We have the new data on the ALLELE data set, and then we have, at the same time, the data coming from this request of the FDA that will have the need to see all the manufactured -- nearly all the manufactured lots by Atara there. So we aligned with the FDA during our recent interactions, and that was just a couple of weeks ago, where that's -- the best way forward will be to have, in parallel, a Type B meeting on the CMC aspect, the Type B meeting on a clinical, so you can look at the clinical data there. And then we can have a pre-BLA that will just be the more check-the-box, administrative part of the pre-BLA meeting.

So that's why it's put together with these 2 Type B meeting and then a pre-BLA. And in the past, it was supposed to be to move directly from the Type B CMC to a pre-BLA. Jakob, anything to add to that?

No. I think that you've summed it up very well, Pascal.

Does it answer your question, Matt?

Yes. I guess it seems like maybe there's something that's come up that's required another Type B meeting since that, obviously, wasn't planned originally, but okay.

Just wondering, you've previously said that you had about 15 lots manufactured for comparability. I wonder if that's still kind of the number you plan to go into this Type B meeting with on the CMC side or if there's any additional lots that will be used in the comparability?

Maybe, Jakob, you want to start and José can chime in, if needed.

Yes, absolutely. So Matt, I think this really speaks to how the thinking of the FDA has evolved and where we now have this clarity of guidance because, you're right. What we presented to the agency was 15 lots from each process version, which really gives us robust statistical power for that comparison. Now for example, if you talk about a small molecule inhibitor or you talk about an antibody, generally speaking, they want about 3 lots to compare statistics on that. We're providing 15 of each process version.

But then the agency came out and said, "Listen, we really want to assess all your lots for pivotal and commercial," which is really more consistent with the requests that they made for allo CAR T because...

Autologous.

I'm sorry, auto CAR T -- I'm sorry, auto is what I'm referring to, where each one of those products -- each one of those sub products was an individual drug for that individual patient. So the agency wanted to see every single one of those.

Now the whole idea with allogeneic T cell therapy is that you're able to treat many patients from your inventory. So you don't need to make one product from each patient. So we have proposed this robust statistical approach where we gave them 15 lots from each of the process versions, and -- but the agency did fall back to this approach with us and said we want to see all lots.

And we said, "Okay, fine." We can deliver that with our pivotal to commercial material, and that's exactly what we're providing to them in this Type B CMC meeting, which is where we have confidence that we're going to be able to resolve this comparability issue.

José, anything to add to that?

Yes. To the question of beyond the 15 lots per process version, in total, we're presenting now 74 lots to the agency.

That represents more than 95% of the total lots produced. So that's not exactly what the agency wants to see. And we believe that the main rationale is that they want to confirm the robustness of manufacturing process for cell therapy and are they used to with autologous. They have habits now.

Okay. One last question. On the magnetic transmission, MTR, data that we're going to see, is this something you've collected on every patient? Or how many patients should we expect? Because I can't recall this being something that was listed as a data being collected. And just will it be -- how many time points? Is it a pretreatment and then now a 12- or 18-month follow-up? What kind of -- can you give us anything else on what to expect here?

AJ?

Sure. So the way the MTR works is it's really an analysis you can do when you've got a good quality MRI done. So when you have a good quality MRI result, you can actually go ahead and do the MTR analysis at whatever time points.

So for -- as you know, for our Phase I study, we did 6 months and 12-month time points for EDSS. So that's the kind of thing we'll be looking to talk about in the -- with MTR. And then going forward in the RCT, literally, every single time point that an MRI is done, we'll be able to assess the MTR as well.

And on the number of patients, that's all the patients in the Phase I?

All the patients that have a good MRI will have a result there, yes. For Phase I, yes.

Our last question comes from the line of Ben Burnett with Stifel.

This is Kailie Briza on for Ben Burnett. We just have 2 kind of quick ones. I was wondering if you guys could give any additional color on what we might see at the ATA2271 readout, the first one, in terms of maybe duration of response or the number of patients we might see? And then, additionally, I'm wondering, I had a question for ATA3219, if you guys are planning on releasing any preclinical data for that?

Thank you for your question. Jakob, do you want to take these questions?

Yes, absolutely. So thank you for the question. In terms of ATA2271, which is our autologous mesothelin CAR T program, which we're doing with Memorial Sloan Kettering. Obviously, it's in the Bayer partnership as well, as we've announced, we do plan on presenting the first clinical data at a relevant meeting -- medical meeting before the end of this year. So we're certainly intending on presenting that clinical data.

Now we do plan on presenting safety, efficacy biomarker data from the study. And we have enrolled the first cohort of patients on the study with our partners at MSK, and we're currently enrolling the second cohort as well. So again, depending on data maturity and so forth, you'll see these various elements.

And I do want to highlight, this program, we think, is really quite innovative and interesting because, yes, it's autologous. And it has this 1XX co-stimulatory domain that we've been licensed from Michel Sadelain and his team, which we think is a potentially best-in-class co-stimulatory domain for CAR T. And it also has the PD-1-dominant negative receptor, which provides intrinsic overcoming of the immunosuppression of tumor PD-L1. So the auto program has both of these components.

Now obviously, we're working also on the allogeneic program, 3271, and that's moving towards an IND filing, where, at this point, we're leveraging our EBV T cell platform additionally there. Now in terms of ATA3219, and we're very excited about that program, it's our first allogeneic CAR T cell program out of the gate. It's directed against CD19. We do believe this is a best-in-class, potentially, program.

And we did present at ASH last year in 2020, preclinical data from that 3219 program. So we can certainly -- that data is certainly available from ASH. And that also leverages this 1XX co-stimulatory domain from Dr. Sadelain and his team at MSK, and we're excited about that forthcoming IND submission. Pascal anything?

The only thing is to remind everyone that this program is also, we believe, supported by this clinical proof of principle that was established by the team at Memorial that show at the Congress in 2020 that similar type of construct based on EBV T cells from healthy donors to which they have added a CD19 CAR T in that case with a traditional co-stimulatory domain, then they treated patients with advanced B-cell malignancies. And they achieved an 83% CR rate.

And that study was quite amazing and unique in a sense that they followed patients for a very long time, and that CR rate was maintained over a median follow-up of nearly 2 years. So I think that's really a very impressive data set, albeit on a small number of patients, but with long durability of response and excellent safety. So that's a nice proof of principle for what we want to achieve there as a potential best-in-class, in particular, adding 1XX as a co-stimulatory domain. Any further questions?

That concludes our question-and-answer session for today. Thank you for joining the Atara Biotherapeutics' Second Quarter 2021 Financial Results Conference Call. You may disconnect your lines at this time.

Thank you.