Earnings Call Transcript - ATRA Q2 2021

Operator, Operator

Good afternoon, everyone, thank you for standing by. And welcome to the Atara Biotherapeutics Second Quarter 2021 Financial Results Conference Call. At this time, all participants are in a listen-only mode. A question-and-answer session will follow the formal presentation. Please be advised that today's call is being recorded. I now would like to hand the call over to Eric Hyllengren, Vice President of Investor Relations and Finance at Atara Biotherapeutics. Please go ahead, sir.

Eric Hyllengren, VP of Investor Relations and Finance

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 and 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. Jose 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?

Pascal Touchon, CEO

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 three of our strategic priorities, tab-cel, ATA188 in multiple sclerosis, and our next-generation allogeneic CAR T programs. Supported by a breakthrough therapy designation, we have been having regular dialogues since January with the FDA. We recently conducted positive meetings with the regulatory 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 methodologies for evaluating comparability between tab-cel clinical and commercial products. In addition, the FDA asked for and we will provide 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. Clinical data from the historical non-pivotal study will not be pooled with the pivotal ALLELE study data; rather, we intend to present these data in parallel as part of the BLA submission. Importantly, at this time, the FDA has made no new request of 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 the finalization of CMC Module 3 post the FDA submission. Turning to the pivotal ALLELE study, we have recently successfully completed the analysis of the Q2 data that occurred previously requested by the FDA. Top line data shows a 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. These data from a pivotal study are impressive for such an ultra-rare and high-unmet need condition like relapsed refractory PTLD where patients have no treatment options. The latest data will still 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 this Phase 3 ALLELE data at an appropriate congress in Q4 2021. Looking ahead, we know our clarity on the required next steps for resolution and submission of the BLA for tab-cel. Although these have taken some time, as Atara is a trailblazer for allogeneic cell therapy as a whole and is paving the way for the first-ever allogeneic off-the-shelf T cell therapy to which figures we're finding, we now expect to complete the BLA submission for tab-cel in Q1 2022. Our investment in US commercial readiness activities has been shifted to this new timing, gating of spending versus what was previously anticipated, as we now plan for tab-cel approval and US 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 US 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 the EMA, and cleared all compliance checks, so we can now move forward to submit the EU market authorization application for patients with EBV positive PTLD in November of 2021. In parallel, there is a strong level of interest from ex-US partners, and our partnering discussions are progressing very well, in line with our expectation to secure a partner for Europe by Q4 2020. Meanwhile, we are also actively enrolling patients in our tab-cel Phase 2 multi-cohort study in other EBV-driven cancers. The six study populations of which the largest falls through our EBV positive AID LPD, and EBV positive PID LPD may support meaningful labor 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. This will include new magnetization transfer ratio imaging data and imaging biomarker linked with myelination, in addition to the two-year clinical data update from the Phase 1a 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 2 randomized double-blind placebo-controlled study or EMBOLD study. We are on track to conduct an interim analysis of the 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 discussions with the FDA regarding potential study adjustments 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 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 among top US 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 end point. Moving to our CAR T portfolio and first, our mesothelin franchised program ATA2271 and ATA3271. These mesothelin-targeted CAR T products are benefiting from a global strategic collaboration with Bayer, which is off to a strong start. For ATA2271 or autologous mesothelin CAR T program, we expect to present the first update on Phase 1 data for patients with advanced mesothelioma in Q4 2021. The off-the-shelf allogeneic version of this mesothelin CAR T program, ATA3271, using a PD1 dominant-negative receptor and 1XX CAR cosignatory 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've got to 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 plan expand 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 the 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 continue to access cell therapies. With the hard work of the Atara team, we are on a clear path to file top cell regulatory submissions and bring this life-saving medicine to patients in need. I will now turn the call over to Jakob. Jakob?

Jakob Dupont, EVP and Global Head of Research and Development

Thank you, Pascal. I am pleased to provide further details on the progress we made during the second quarter in advancing our three 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 two 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 the 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 the 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 3 ALLELE pivotal study. Top line data evaluated through independent oncologic and radiographic assessment shows a 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 the 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. Request to the 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 positive 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 a 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, the long-term, two-year clinical data from the Phase 1 open-label extension, and new translational data from the Phase 1 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 2 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 franchised 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 we believe that this therapy could be a best-in-class treatment in B-cell malignancies as there is still a significant unmet need despite increased therapeutic options. Finally, I would like to extend a warm welcome to our newest leadership team member, Chief Scientific Officer, Dr. Cokey Nguyen. Cokey comes to us 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

At this time, we'll be conducting a question-and-answer session. Our first question comes from the line of John Newman with Canaccord Genuity. You may proceed with your question.

John Newman, Analyst

Hi, there. Thanks for taking my question and congrats on the good progress here. Jakob, you mentioned the submission has been made, a request for a Type B meeting with the comparability data for tab-cel. Just 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 a longer follow-up? Thanks.

Pascal Touchon, CEO

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

Jakob Dupont, EVP and Global Head of Research and Development

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

Pascal Touchon, CEO

And the second question on clinical data beyond ALLELE.

Jakob Dupont, EVP and Global Head of Research and Development

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 days 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 EIP 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 non-comparability between historical and pivotal material.

Pascal Touchon, CEO

Does it answer your question, John?

John Newman, Analyst

Yes, it does. Thank you.

Pascal Touchon, CEO

Thank you.

Operator, Operator

Our next question comes from the line of Jonathan Miller with Evercore ISI. You may proceed with your questions.

Jonathan Miller, Analyst

Hey, guys, thanks for taking my questions, and congrats on the progress. It does seem like the FDA is being pretty cautious on the tab-cel 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 back towards the back end of the prior guidance. I just wondered, what's the gating factor on those INDs going forward from here?

Pascal Touchon, CEO

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

Jakob Dupont, EVP and Global Head of Research and Development

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 six months of follow up on those patients since the time of response is detected. 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 and provided it to our independent review facility for independent oncologic and radiographic response. It really fits those criteria of six months duration of response after that initial response is detected. And that's a pretty standard request from the agency.

Pascal Touchon, CEO

Yes. Another thing is the fact that we align with the agency on the durability of response they want to see, and we have this data now makes us very confident in the strength of this data package that we will present in forthcoming Type B clinical meeting. So on your second question, is just that we have refined our thinking on the different manufacturing timelines for this program and development that is needed to file the IND, the work we are doing on this platform as we progress on the 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 will be of course Atara filing the IND, versus for ATA3271 will be Bayer filing the IND there. Now, we are also trying in developing this IND package, to make sure that we can optimize our chance of adding to best-in-class platforms for allogeneic CAR T, and this is where ATA3219, in particular, could have a significant potential advantage in optimizing characteristic of the cells to make sure that we can leverage the innate properties of EBV T-cells together with 1XX as a costimulatory domain to really make something that could go to the clinic with the potential and the goal to be best-in-class in B-cell malignancies. Does it answer your question, Jon?

Jonathan Miller, Analyst

Yes, absolutely. Thank you.

Operator, Operator

Our next question comes from the line of Salim Syed with Mizuho Securities. You may proceed with your question.

Salim Syed, Analyst

Great. Good afternoon, guys, and 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 actually refers to myelination patterns, are you seeing or you think you're seeing remyelination with ATA188? And 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 accelerated approval around Alzheimer's. Thank you.

Pascal Touchon, CEO

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 your plan with the FDA in terms of how this could be used as a biomarker?

AJ Joshi, Chief Medical Officer

Yes, thanks, Pascal. Hey, Salim. With the MTR data, you've likely heard that when examining MRI biomarkers, myelination is the most frequently utilized one across various studies. This has shown a correlation with a decline in EDSS, indicating a reduction in disability. Lower MTR levels indicate demyelination, which corresponds to a decline in disability. However, no one has demonstrated improvement in disability in progressive conditions, as no product has achieved that yet. What's noteworthy is that in relapsing diseases, where there's active lesion treatment with therapies effective in inflammatory conditions, MTR can increase due to remyelination after inflammation subsides. Thus, MTR increases with remyelination and should not be observed in progressive settings. We aim to establish that MTR is a recognized measure of both demyelination and remyelination and apply it to our current study data. We look forward to presenting this data in October. Currently, MTR has not served as a surrogate marker, likely due to limited reasons to examine disability improvement alongside MTR changes. We plan to monitor MTR closely throughout the EMBOLD study and engage with the FDA, including discussions about MTR. However, it's too early to declare it an established biomarker, though it is recognized within the scientific community.

Pascal Touchon, CEO

Yes, as AJ mentioned, one of the endpoints will be tracked in the current randomized control trial. We expect to receive data in October from the Phase 1 study, and later we will have additional data from the Phase 2 study when it becomes available. This is part of our strategy to utilize a specific biomarker that has been featured in several studies, although it has not yet been linked to improvements in disability, which could be very promising.

Operator, Operator

Our next question comes from the line of Phil Nadeau with Cowen. You may proceed with your question.

Phil Nadeau, Analyst

Good afternoon, and congrats on the progress, and thanks for taking our question. 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, you talk a bit more about your confidence that the FDA will find the pivotal and commercial material comparable. Thanks.

Pascal Touchon, CEO

Certainly, Jose, 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 data that will be seen to decide positively on comparability. Jose?

Jose Vidal, Head of GMP Quality and Process Sciences

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 producer virus into a full GMP commercial-grade producer cell line, and we also switched the manufacturing place of the virus to our own facility from the previous CMO as the CMO has no capacity to supply commercial volumes. We have done full characterization of 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.

Pascal Touchon, CEO

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

Jakob Dupont, EVP and Global Head of Research and Development

Absolutely. So I think one of the really important things so that we learned from the FDA is their thinking evolved around tab-cel which is the first allogeneic T-cell product which is going across for FDA approval. We learn that they have this requirement now to see the data from all the lots that have been created in order for 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 analysis. So having the agency provide us the lay of the land and what the requirements were in terms of sharing the totality of that data, that is something that's 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 Jose 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.

Pascal Touchon, CEO

Yes. And we're pretty much sure that the 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 Jose just explained. Does it answer your question?

Phil Nadeau, Analyst

Great. For my last question, I would like to know what the rate-limiting factor is for the Q1 filing. Is it the completion of the comparability analysis, or is there something else causing a delay?

Pascal Touchon, CEO

Jakob?

Jakob Dupont, EVP and Global Head of Research and Development

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 we'll 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 two 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 two 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 two type B meetings then the pre-BLA meeting and then we complete the submission of the BLA.

Phil Nadeau, Analyst

Perfect.

Pascal Touchon, CEO

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 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 and all the lots made by Atara. So in terms of delivering what the FDA is asking for, we feel very clear.

Operator, Operator

Our next question comes from Matt Phipps with William Blair. Please go ahead with your question.

Matt Phipps, Analyst

Good afternoon, and thank you for taking my question. I have a couple of inquiries. First, was it always planned to have a Type B clinical meeting following the Q2 data cut? It seems that this would have made it impossible to meet your guidance for Q3 submission, especially considering the CMC issues. I’m just curious if this is a new development, as it does not appear to align with your earlier guidance on timelines, aside from the CMC complications.

Pascal Touchon, CEO

Sure, let me address the first question about the guidance, and then I'll take your other questions. The guidance we provided for Q3 was primarily based on the Type B CMC meeting we held in Q2. Following that meeting, we anticipated moving towards a pre-BLA meeting around August, contingent on the data cut, and then submitting the BLA by the end of Q3. That was the foundation of our guidance. Currently, we have two factors to consider. We now have new data from the ALLELE data set, and we also received a request from the FDA to review virtually all manufactured lots by Atara. In our recent discussions with the FDA, a couple of weeks ago, we concluded that the best path forward would be to request a Type B meeting to address the CMC aspects in parallel with a meeting focusing on clinical data. This means that the pre-BLA meeting will serve more as a necessary administrative step. This is why we are now scheduling two Type B meetings followed by the pre-BLA, whereas previously, we intended to transition directly from the Type B CMC to the pre-BLA. Jakob, do you have anything to add?

Jakob Dupont, EVP and Global Head of Research and Development

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

Pascal Touchon, CEO

Does it answer your question, Matt?

Matt Phipps, Analyst

Yes, I guess. It seems like maybe there is something's that have 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 manufacturers from 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 is any additional lots that will be used in the comparability?

Pascal Touchon, CEO

Yes. Maybe Jakob, do you want to start, and Jose can chime in if needed.

Jakob Dupont, EVP and Global Head of Research and Development

Yes, certainly. Matt, this highlights how the FDA's perspective has shifted, leading to clearer guidance. What we submitted to the agency included 15 lots from each process version, which provides strong statistical power for comparison. Typically, for a small molecule inhibitor or an antibody, about three lots are sufficient for statistical comparisons. We're supplying 15 lots from each process version, but then the agency indicated that they want to evaluate all lots for pivotal and commercial use. This aligns with their request for ALLELE CAR T, where each cell product was treated as a separate drug for each patient, necessitating a review of every product. The concept behind allogeneic T cell therapy is that many patients can be treated from a single inventory, eliminating the need to create a unique product for each individual. We proposed a comprehensive statistical strategy featuring 15 lots from each process version, and the agency agreed to this approach, indicating they want to see all lots. We confirmed that we could provide that data with our pivotal to commercial material. This is exactly what we're presenting at this Type B CMC meeting, and we are confident we will address the comparability issue.

Pascal Touchon, CEO

Jose, anything do you want to add?

Jose Vidal, Head of GMP Quality and Process Sciences

Yes. To the question of beyond the 15 lots for process variation, in total, we're representing now 74 lots to the agency.

Pascal Touchon, CEO

Okay. All right. Yes. And that represents more than 95% of the total lots produced, so that's exactly what the agency wants to see. And we believe that the main rationale is that they want to confirm the robustness of the manufacturing process for cell therapy and are they used to with autologous, you know, they have habits now.

Matt Phipps, Analyst

Okay. One last question on the magnetic transmission, is the MTR data we will see based on every patient you have collected data from? How many patients should we expect, as I don't remember this being mentioned as part of the data collection? And could you provide details on how many times this data is collected before treatment and during the 12 or 18-month follow-up? What can we expect in this regard?

Pascal Touchon, CEO

AJ?

AJ Joshi, Chief Medical Officer

Sure. So the way the MTR works is it's really 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 interim analysis at whatever time points. So for as you know for our Phase 1 study, we did six months and 12 months' time points for EDSS, so that's the kind of thing we'll be looking to talk about 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.

Pascal Touchon, CEO

And on the number of patients, that's all the patients in a Phase 1.

AJ Joshi, Chief Medical Officer

All the patients that have a good MRI will have results there, yes.

Pascal Touchon, CEO

Yes.

Operator, Operator

Our last question comes from the line of Ben Burnett with Stifel. You may proceed with your question.

Unidentified Analyst, Analyst

Hi, this is Kylie Brisa on for Ben Burnett. Thanks for taking our questions. We just have two quick ones. I was wondering if you could provide any additional information on what we might expect at the ATA2271 read-out, specifically regarding the duration of response or the number of patients. Additionally, I have a question about ATA3219—are you planning to release any preclinical data for that? Thank you.

Pascal Touchon, CEO

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

Jakob Dupont, EVP and Global Head of Research and Development

Thank you for the question. Regarding ATA2271, our autologous mesothelin CAR T program in collaboration with Memorial Sloan Kettering, we plan to present the first clinical data at a relevant medical meeting before the end of this year. We intend to share safety, efficacy, and biomarker data from this study, and we have enrolled the first cohort of patients and are currently enrolling the second cohort. The timing of various elements will depend on data maturity. We believe this program is innovative due to its autologous nature and the 1XX costimulatory domain licensed from Michel Sadelain's team, which we see as potentially best-in-class for CAR T. Additionally, it includes the PD1 dominant-negative receptor, which helps overcome tumor PD-L1 induced immunosuppression. We are also progressing on the allogeneic program ATA3271, moving towards an IND filing, utilizing our EBV T-cell platform. As for ATA3219, we are very enthusiastic about this first allogeneic CAR T-cell program targeting CD19, which we believe has the potential to be best-in-class. We presented preclinical data from ATA3219 at ASH last year, and that data is available. This program also utilizes the 1XX costimulatory domain from Dr. Sadelain and his team, and we are looking forward to the upcoming IND submission. Pascal, do you have anything to add?

Unidentified Analyst, Analyst

Great.

Pascal Touchon, CEO

No. 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 was shared at the Congress in 2020 that similar type of construct based on EBV T-cell from healthy donors to which they have added CD19 CAR T, in that case, with the traditional costimulatory domain, then they treated patients with advanced B-cell malignancies and they achieved an 83% CR rate. 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 two years. So I think that's really a very impressive data set albeit on the 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 now 1XX as a costimulatory domain. Any further questions?

Unidentified Analyst, Analyst

That's it from me. Thank you.

Pascal Touchon, CEO

You're most welcome.

Operator, Operator

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.