Mersana Therapeutics, Inc. (NASDAQ:MRSN) Q1 2023 Earnings Conference Call May 9, 2023 8:00 AM ET
Company Participants
Jason Fredette – Senior Vice President, Investor Relations and Corporate Communications
Anna Protopapas – President and Chief Executive Officer
Arvin Yang – Chief Medical Officer
Brian DeSchuytner – Chief Financial Officer
Conference Call Participants
Brian Cheng – J.P. Morgan
Jonathan Chang – SVB Securities
Colleen Kusy – Baird
Kaveri Pohlman – BTIG
Ashiq Mubarack – Citi
Boris Peaker – Cowen
Asthika Goonewardene – Truist
David Nierengarten – Wedbush Securities
Operator
Good morning, and welcome to Mersana Therapeutics First Quarter 2023 Conference Call and Webcast. Currently, all participants are in listen-only mode. There will be a question-and-answer session at the end of this call. Please note, this event is being recorded.
I would now like to turn the call over to Jason Fredette, Senior Vice President, Investor Relations and Corporate Communications. Please proceed.
Jason Fredette
Good afternoon, everyone. Before we begin, please note that this call will contain forward-looking statements within the meaning of federal securities laws. These statements include, but are not limited to, those related to the therapeutic potential of our product candidates and the potential of our platforms, business strategy, clinical trial designs, execution and data releases, regulatory plans and objectives, commercial opportunities, collaborations and potential associated payments, operating expenses and cash runway.
Each of these forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from those projected in such statements. These risks and uncertainties are discussed in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 28, 2023 and in subsequent SEC filings.
Our filings are available at sec.gov and on our website, mersana.com. Except as required by law, we assume no obligation to update forward-looking statements publicly even if new information becomes available in the future.
With that, let me turn the call over to Anna Protopapas, our President and Chief Executive Officer.
Anna Protopapas
Thank you, Jason. And hello, everyone. Welcome to our conference call. Joining me today with prepared remarks are Mersana’s Chief Medical Officer, Arvin Yang; and Chief Financial Officer, Brian DeSchuytner. We also have other members of management here who will be available to answer your questions.
2023 is shaping up to be a potentially transformational year for Mersana. We are on the verge of a topline data readout for a first in class ADC UpRi, while we also execute on a comprehensive clinical development plan for this candidate with a potential to address significant unmet medical needs for patients suffering from ovarian cancer.
We are advancing our own pipeline and are also collaborating with several other organizations utilizing our three proprietary ADC platforms and thanks in a large part to the successes we’ve had on the business development front we are doing all of this on the strong financial footing.
We are pursuing our objectives during a historic period for ADC as evidenced by numerous new collaborations, additional approvals, exciting new data presentations, and one of the largest biotech acquisitions to date. In platinum resistant ovarian cancer, specifically, mirvetuximab just recently reaffirm the single arm accelerated approval pathway.
And from a commercial perspective, the early uptake of testing and treatment for this product has demonstrated both the high unmet medical need in platinum resistant ovarian cancer and the willingness of treating physicians to embrace a targeted approach to therapy.
And so we are in the midst of a very exciting period. Thanks to a decade of hard work by the team here at Mersana, the innovative approach that we have taken to ADC platform development and our advanced stage of clinical development with UpRi, we believe we’re well-positioned to add to the momentum in the field.
We are putting a heavy emphasis on our strategy to establish UpRi as a foundational medicine ovarian cancer as we advance three ongoing clinical trials that seek to address areas of high unmet medical need. The first is UPLIFTour single arm registration trial in platinum resistant ovarian cancer as evidence by our rapid enrollment of approximately 270 patients in this trial and recent product uptake in the platinum resistant phase, the unmet medical need for disease late-stage patients is very high.
UP-NEXT is our Phase 3 clinical trial of UpRi as a monotherapy maintenance treatment in recurrent platinum sensitive ovarian cancer. This trial is designed to serve as a post-approval confirmatory trial of UpRi in the U.S. significantly increase our potential market opportunities by supporting expansion into earlier lines of therapy and support potential approvals outside the U.S.
And then there’s UPGRADE-A, our Phase 1 combination trial of UpRi with carboplatin in platinum sensitive ovarian cancer. We hope this data will inform our path to early lines of treatment. With top line data from UPLIFT plan for mid-year after the upcoming oncology conferences in June and a potential BLA submission around the end of the year, we have began to prepare for potential commercialization.
For instance, we have small forms, a small core team of commercial professionals with deep ovarian cancer experience. Those our medical affairs function and we’re working diligently to ensure we can hit the ground running with NaPi2b tested. Beyond UpRi, we continue to make progress in our Phase 1 trial of XMT-1660, our B7-H4 Dolasynthen product candidate and are working to address the clinical holds the FDA recently placed on our Phase 1 clinical trial of XMT-2056.
To further discuss our clinical plans and progress, I’ll turn the call over to Arvin.
Arvin Yang
Thank you, Anna. Let’s begin by discussing UPLIFT. Platinum resistant ovarian cancer remains an area of significant unmet medical need. Patients at this most advanced stage of disease are heavily pretreated and have a very poor prognosis. For most patients, treatment options are limited to single agent chemotherapy, which is consistently demonstrated an objective response rate of approximately 12% in previous trials.
We’re seeking to fill this significant gap in care with UpRi. Following the release of data from MIRASOL and based on mirvetuximab’s label, it is worth noting several key differences in our trial populations. In UPLIFT, we enrolled an all-comers population and retrospectively are determining NaPi2b positive status as compared to MIRASOL, which pre-selected for folate receptor alpha positive patients.
We believe that at least a majority of ovarian cancer patients have NaPi2b positive expression. In fact, the large NaPi2b dataset that has been presented to date assessing roughly 400 unique tissue samples suggest that 59% of ovarian cancer patients are NaPi2b positive. In contrast, available data suggests that only a minority of ovarian cancer patients have folate receptor alpha positive expression.
We also enrolled patients in UPLIFT who have received one to four prior lines of therapy compared to both SORAYA and MIRASOL, which enrolled patients who had received one to three prior lines. We believe the differences observed between SORAYA and MIRASOL serve as a reminder how ORR can be influenced by the type and level of patient pre-treatment.
We also enrolled patients with grade 2 underlying neuropathy and uplift, while these patients were excluded from both SORAYA and MIRASOL. Our broad inclusion criteria were based largely on the encouraging data from our dose expansion cohort. UPLIFT’s primary endpoint is the investigator assessed objective response rate or ORR in the NaPi2b positive population. The primary endpoint will aim to exclude the 12% objective response rate for single agent chemotherapy from the 95% confidence interval.
In addition to ORR, we expect the FDA to evaluate duration of response or DOR along with safety and tolerability in the overall context of the UPLIFT data. In addition to UPLIFT, we are continuing to enroll patients in our Phase 3 UP-NEXT trial. There is a substantial need for new ovarian cancer maintenance treatments, as many patients have already exhausted available maintenance options by the time they have recurrent disease.
And with the recent label restrictions related to PARP inhibitors, this need is only getting larger. UP-NEXT is enrolling 350 patients. These patients must be NaPi2b positive and they must have achieved stable disease or better in response to their prior induction chemotherapy. In recognition of the lack of standard of care in the recurrent maintenance, the trial is randomizing patients 2:1 to receive UpRi or placebo. Our primary endpoint for the trial is progression-free survival or PFS by blinded independent central review.
Our third ongoing UpRi trial UPGRADE-A is evaluating UpRi in combination with carboplatin. Historically, the combination of carboplatin and paclitaxel has served as the standard of care in earlier lines of ovarian cancer treatment. However, distinct tolerability challenges including high rates of severe neutropenia, peripheral neuropathy and alopecia have limited the ability to dose this combination beyond six cycles.
In UPGRADE-A, patients receive UpRi in combination with carboplatin for up to six cycles as an induction treatment and UpRi is then continued as a monthly maintenance monotherapy. We believe the differentiated tolerability profile we observed for UpRi in our monotherapy dose expansion trial without toxicities commonly seen with other ADC platforms may position it well for using combinations. We were pleased to complete dose escalation in UPGRADE-A and move into dose expansion in the first quarter. And we’re looking forward to sharing initial interim data in the second half of this year.
Before delving into our other clinical stage cytotoxic ADC XMT-1660. Let’s touch on XMT-2056, which is our HER2 directed Immunosynthen STING-agonist ADC. In March, we voluntarily suspended our Phase 1 trial of this product candidate following a Grade 5 series adverse event or SAE, that was deemed to be related to XMT-2056. The FDA then placed the trial on clinical hold. The SAE occurred in the second patient enrolled at the initial dose level in the dose escalation portion of the trial, and it was obviously quite unfortunate and unexpected.
In recent weeks, we’ve received plasma PK and cytokine data for the two patientsm, who are dosed in the trial prior to the clinical hold and we’re continuing to analyze these data. We’re evaluating next steps for the program and we’ll prepare a response to the FDA’s clinical hold letter. We will provide an update on our plans once they’ve been solidified.
Now let’s turn to XMT-1660. Our Dolasynthen product candidate targeting B7-H4. We see B7-H4 as a particularly compelling target given its high expression in a variety of tumors and its limited expression in healthy tissue. XMT-1660 is equipped with a precise target optimized drug to antibody ratio of six and our DolaLock payload with controlled bystander effects.
I’m happy to report that we are making good progress in the dose escalation portion of our multicenter Phase 1 trial, which is enrolling patients with breast, endometrial and ovarian cancers and remain firmly on track to complete this portion of the trial later this year.
With that, let’s turn the call over to our Chief Financial Officer, Brian DeSchuytner, for an update on our financials. Brian?
Brian DeSchuytner
Thank you, Arvin. We are approaching our upcoming topline data readout in a strong financial position. Beyond the $170 million in upfront payments we received from collaborations over the past year, we’re beginning to see the downstream benefit of those transactions in the form of initial discovery milestone revenues. We ended the first quarter with approximately $274 million in cash, cash equivalents and marketable securities, and we also have a line of credit available to us. We expect our available funds to support our operating plan commitments into the second half of 2024, well past several potential milestones of significance.
It should also be noted that our cash runway guidance does not assume any potential milestone payments from our current collaborations or proceeds that we may realize from future collaborations.
Now for a brief recap of our P&L for the first quarter. Net cash used in operating activities, which approximately $29 million for the first quarter of 2023. Collaboration revenue for the first quarter of 2023 was $7.8 million compared to $2 million for the same period in 2022. The year-over-year increase was primarily related to our collaboration agreements with Merck KGaA and Asana.
Research and development expenses for the first quarter of 2023 were $47.3 million compared to $35.8 million for the same period in 2022. Non-cash R&D related stock-based compensation expense for the first quarter of 2023 was $3.3 million. The year-over-year increase in R&D expenses was primarily related to higher manufacturing and clinical costs related to UpRi and an increase in headcount.
General and administrative expenses for the first quarter of 2023 were $18.3 million compared to $12.8 million during the same period in 2022. Non-cash G&A related stock-based compensation expense for the first quarter of 2023 was $3.1 million. The year-over-year increase in G&A expenses was primarily related to increases in medical affairs and pre-commercial activities and headcount. Mersana’s net loss for the first quarter of 2023 was $56.2 million compared to a net loss of $47.3 million for the same period in 2022.
Now I’ll turn the call back over to Anna for a few closing remarks.
Anna Protopapas
Thanks, Brian and Arvin. In summary, 2023 is lining up to be a transformative year for Mersana we’re excited by all that lines ahead. We expect to import top line data for UPLIFT midyear following the major oncology conferences in June with a potential BLA submission plan for around the end of the year. We plan to significantly advance enrollment in our confirmatory trial UP-NEXT. We’ll also advance the dose expansion portion of UPGRADE-A and expect to report initial entering data from this trial in the second half of the year.
Our team will continue to work to evaluate next steps related to development of XMT-2056. And finally, we plan to complete the dose escalation portion of our Phase 1 trial of XMT-1660 this year. We look forward to keeping you updated on all our progress.
Now, let’s open the call to your questions. Operator, would you please provide the instructions?
Question-and-Answer Session
Operator
Thank you. We will now begin the question-and-answer session. [Operator Instructions] And today’s first question comes from Brian Cheng with J.P. Morgan. Please go ahead.
Brian Cheng
Hey guys. Thanks for taking my question this morning. Maybe just one on ASCO – heading into ASCO, we saw that you have a presentation there on expression of folate receptor alpha and also NaPi2b. So can you shut some light on what that presentation entail and what should we be looking for there? And then I have a follow-up. Thank you.
Arvin Yang
Thanks, Brian. This is Arvin. I can address that question. So we look forward to sharing information at ASCO and it’s a data set that comes from our expansion cohort of our UpRi study, the Phase 1 study. And really the purpose of it is to evaluate NaPi2b expression and folate receptor alpha expression, recognizing that in other datasets external to the one that we’re presenting. We’ve described how NaPi2b is approximately 59% based on 400 tumor samples relative to what we’ve seen from the FDA review of me mirvetuximab, where 29% was the positivity folate receptor alpha.
Brian Cheng
Great. And maybe just one on UPLIFT topline, heading into UPLIFT topline later this year – later midyear, outside of overall response rate and duration of response, are there any additional efficacy measures that we could get at the top of the topline?
Anna Protopapas
So I think as we’ve said, the topline will be midyear after the June oncology conferences and we will be showing overall response rate in the primary endpoint as well as the secondary endpoint duration of response and of course the key safety overview of the – for the study.
Brian Cheng
Thanks, Anna. Thank you.
Operator
Thank you. And our next question today comes from Jonathan Chang with SVB Securities. Please go ahead.
Jonathan Chang
Good morning. Thanks for taking my questions. First question on the recent MIRASOL results, how does that impact your thinking on the UpRi opportunity and strategy?
Anna Protopapas
We remain very excited about the UpRi opportunity, Jonathan. As you know, and this is evident from what we’ve seen from ImmunoGen, this is an area of high unmet medical need. There’s a desperate need by physicians and patients for new agents and we remain very excited about UpRi. We’ve shown robust efficacy and a differentiated tolerability profile in the expansion cohort. And of course, as Arvin just alluded to, we have an agent that has a very significantly different prevalence and the overlap between folate high and NaPi2b high is quite limited. So there’s a desperate need for new agents for these patients and we hope UpRi will fill that gap.
Jonathan Chang
Got it. Thank you. And second question, when could we see initial data from the B7-H4 program?
Anna Protopapas
What we’ve guided to and I think Arvin mentioned on the call is that we expect to complete dose escalation by the end of this year. Dose escalation is proceeding as planned and at that point I think we’ll have not yet guided to data disclosures, but we are very excited about the program, we think this is a great target for an ADC and for our platform. So we’ll make that decision on data disclosure as we approach completion of the dose escalation.
Jonathan Chang
Got it. Thanks for my questions.
Operator
Thank you. And our next question today comes from Colleen Kusy with Baird. Please go ahead.
Colleen Kusy
Hi, good morning and thanks for taking our questions. On the UPLIFT readout that’s coming up in midyear. Would you expect to also report data in the overall patient population? And do you have any expectations on what you’d need to show in the NaPi2b low patient population to get a broad label?
Arvin Yang
Sure. Thanks, Colleen. So we do expect to share data not only in the NaPi2b positive population, which is our primary endpoint, but the overall population is a key secondary endpoint. So a response rate in the key secondary endpoint could also support a broader indication. This alludes to actually your second question in relationship to what would you need to see in the low population? So keeping in mind that the benchmark for approval for both of these populations in discussion with FDA really is a single agent chemotherapy response rates of 12%. Now that being said, the response rate in the overall population we would imagine could not be completely driven by the NaPi2b positive population in order to generate that overall population response rate.
Colleen Kusy
Got it. That’s helpful. Thank you. And then on the upgrade data later this year, are you able to say roughly how many patients you’d expect and how much follow-up you’d expect to have?
Arvin Yang
So we had announced last year that we had completed our – well, that we had approximately 12 patients within the dose escalation portion. And then in the first quarter of this year, we had indicated that we had completed dose escalation and initiated the expansion phase. So you can approximate in relationship to how many patients we would have within dose escalation. And the determination will be made just in relationship to how many patients would then be available for presentation in the second half of this year. That also gives you some sense of the follow-up that would be available for those patients.
Colleen Kusy
Got it. That’s helpful. Thank you. And then just last follow-up on the UPGRADE study that’s reading out later. So would the focus there be mainly on safety or can you kind of help us at a bar for efficacy in that readout?
Arvin Yang
Sure. So the primary focus absolutely is safety is a Phase 1 study and it is really driven off the premise that UpRi provides a differentiated profile with non-overlapping toxicities, affording it a great opportunity to combine with standard of care platinum for instance. In addition to that, obviously, being able to continue the UpRi portion of it after completion of the six cycles of combination into the monotherapy. So safety will be the primary focus of this presentation, recognizing that the follow-up to get into the maintenance may not be sufficient at that time point. We will plan to present also efficacy for the available information. But it’s in the context obviously of recognizing safety is the primary focus.
Colleen Kusy
Great. Thanks for taking our questions.
Operator
Thank you. [Operator Instructions] Our next question today comes from Kaveri Pohlman with BTIG. Please go ahead.
Kaveri Pohlman
Yes. Good morning. Thanks for the updates and for taking my questions. For the upcoming ASCO data for expression studies, is that specifically for platinum resistant population. Do you expect to see any changes in NaPi2b expression or the overlap when you move to earlier lines?
Arvin Yang
Thanks for the question, Kaveri. So just for context, obviously, we want to share the presentation for ASCO. But as I mentioned earlier, this will be on a data set that comes from our Phase 1 study. And so that included primarily platinum resistant ovarian cancer patients. There was a proportion of patients that were fourth line plus that could have been platinum sensitive, but again, these were a minority with the patients.
But to your second point in relationship to the prevalence of NaPi2b, we shared actually a variety of different presentations in the past from tumor banks, from our own internal studies that support the consistency of NaPi2b expression by line of therapy as well as from a local and metastatic site perspective. There, I’ll remind folks that 59% with the NaPi2b positivity when looking at one of the largest tumor bank analysis of individual tissue samples of approximately 400 samples.
Kaveri Pohlman
That’s very helpful. Thank you. And for the UP-NEXT study, it’s a novel design, but any insight you could provide on addressable patient population. How different it is from the platinum resistant market. And in terms of benchmarks for PFS, what would you expect out of the placebo arm?
Anna Protopapas
So maybe Arvin can talk to the placebo arm and the protection benefit here. As for the size of the market, we have not given specific numbers, but we do believe that we – that this trial will bring us to a large area unmet medical need, potentially larger than platinum resistant with a positive UP-NEXT trial.
Arvin Yang
And maybe just before I jump into the placebo effect, I’ll just comment that given the emerging landscape of the PARP inhibitors with the recent FDA changes, where PARP inhibitors are no longer approved in the – or restricted primarily to the BRCA and the HRD positives. We see that actually as increasing the unmet need in that recurrent platinum maintenance setting – platinum sensitive maintenance setting.
Kaveri, just to your second question, as far as the activity of placebo, one of the best benchmarks may be the NOVA study. So it’s a study of a PARP inhibitor in the recurrent platinum sensitive maintenance setting and there the placebo arm had a performance of PFS of approximately 4.5 months. But I do want to provide context to that figure, because that was a study performed in an earlier time period where patients may not have received or would not have actually received prior PARP or bev in that era where the study was conducted. In addition to that, this patient population was less heavily pretreated and less refractory, because they did not include stable disease patients to the prior platinum therapy in acknowledgement that the PARP inhibitor and platinum mechanism of action has sufficient similarity that they did not want to include stable disease patients for their study as opposed to in UP-NEXT where we do include these patients.
Kaveri Pohlman
Got it. And maybe like the last one on B7-H4 ADC, from the competitive landscape standpoint and from your experience with UpRi and 1529, can you tell us what advantages the single species ADCs provide?
Anna Protopapas
We didn’t hear the second part of your question. You’re asking for the differentiation versus other B7-H4 ADCs, Kaveri, was that the question?
Kaveri Pohlman
Yes. And you have intensive experience with UpRi and 1529, which was also a single species ADCs. So I just wanted to get some sense what advantages leave homogeneous ADCs provides.
Arvin Yang
Sure. I can start and if the team wants add to that. So I mean, first off, we’re very excited about B7-H4. We think it’s a good target. Given the competitive landscape, I would argue that others agree with us and relationship to that. Before diving into that, actually, let me just clarify. We do actually have extensive knowledge with the Dolaflexin molecule and it’s differentiated safety profile, given that it’s the same payload that’s utilized in UpRi, again, without the severe neutropenia as the ocular toxicities or the neuropathies.
We did evaluate it also in the XMT-1592 program. I just wanted to clarify that was a Dolasynthen molecule with the same payload. Just to clarify, it wasn’t 1529. Now with that being said, we are excited about B7-H4, because it does differentiate relative to and I’ll flag two different companies that are also developing B7-H4.
So Seagen is developing a B7-H4 molecule, but we have DAR – a homogeneous DAR 6 alluding to sort of the point you’re raising. And we believe that through our preclinical data that the DAR 6 did have differential benefit from the standpoint of greater efficacy when looking at our preclinical models. In addition to that, we do expect that from a P&L perspective, it’ll have that differentiated safety profile relative to the MMAE that the Seagen molecule is being developed at where they also have a lower DAR of approximately 3.5. So I think that addresses your question just as far as the differentiated profile.
Kaveri Pohlman
Yes, that’s very helpful. And yes, I meant 92 instead of 29. Sorry about that.
Anna Protopapas
No problem.
Operator
Thank you. And our next question today comes from Ashiq Mubarack with Citi. Please go ahead.
Ashiq Mubarack
Hi team, thanks for taking my questions. I know you made some comments related to building out the commercial infrastructure in the past quarter. Can you comment at all on the size and the reach of the sales force for UpRi you are building out. And maybe any general commentary on how much of an educational UPLIFT you think there needs to be with NaPi2b biomarker testing in the sort of real world setting?
Anna Protopapas
So our commercial efforts are very much focused on pre-launch activities. We’re some ways away from really defining the exact size and details of the sales force. So let me focus on what we are doing now. We have a very small, but impactful medical affairs group that is really working with investigators to increase their awareness of the importance of NaPi2b as a biomarker and to educate on UpRi as a potential therapy in ovarian cancer.
We have really a handful of people with deep ovarian cancer commercial expertise that are really preparing the market plans and ensuring that our diagnostic is available on day one. So that is the effort. A very small group of people has, I believe, been very impactful in ensuring all the work is done for us to be ready with positive data with a BLA and then potentially an upcoming approval to be able to build out that effort.
Ashiq Mubarack
Got it. That’s really helpful. I’m going to ask one more also on the commercial plan. I think in the past, you’ve alluded to your plan to partner UpRi in Europe and in other regions globally. And I just wondering if you can remind us why that’s the right move. I think ImmunoGen made some commentary last week related to the idea that the European market is actually pretty concentrated around a limited number of centers, which cover – maybe covers the majority of the market. So I’m wondering why if you think or thinking about the European opportunity in a similar or very different way given you’re applying to partner?
Anna Protopapas
Yes. Our thoughts are really based on extensive experience across the biotech industry, really investing in an infrastructure in Europe although eventually might be – might pay off is a significant investment. And as you are aware, getting reimbursement in Europe always takes time. So by the time that European infrastructure becomes cash flow positive takes a long longer to get there than in the U.S. And I think that’s what’s driving our thinking, which of course will be refined as we get topline data will be further refined. But I think history will say that small biotech companies that expand to both the U.S. and Europe can – would require significant investment before that commercial infrastructure can really begin to be cash flow positive.
Ashiq Mubarack
Got it. Thanks for taking my questions.
Operator
Thank you. And our next question today comes from Boris Peaker with Cowen. Please go ahead.
Boris Peaker
Great. Thanks for taking my questions. First question on the UPLIFT study, can you set expectations for duration of response and if that is something that you’ve discussed with the FDA, what the agency may be looking for in terms of duration of response?
Arvin Yang
Thanks for the question, Boris. So in discussions with FDA, we’ve aligned that response rates is the primary endpoint for evaluation of efficacy and that’s 12% based upon the multiple Phase 3 studies that we’ve described in the past. Duration of response, certainly, will be expected. It’ll be in the context again of the overall efficacy and safety profile that it’ll be taken into context.
Boris Peaker
Great. And maybe in terms of baseline characteristic, you mentioned that you allowed baseline grade 2, I guess lower neuropathy in the UPLIFT trial, while these patients were excluded from SORAYA and MIRASOL. Just curious can you comment what fraction of these platinum refractor patients have this baseline neuropathy?
Arvin Yang
So we know that most of the patients actually, if not all of the patients that become platinum resistant will have received an agent that can induce neuropathy. Given that [indiscernible] is a heavy offender and other chemotherapists certainly can contribute to that. I don’t have the number specifically for the expansion data available in reference to that, but based on what I just described earlier is that, we do expect a fair proportion of patients to have some degree of neuropathy. That could obviously be intacted if they were to receive further therapy that could cause neuropathy whereby with UpRi we have not seen the severe neuropathies.
Boris Peaker
Great. Thank you very much for taking my questions.
Operator
Thank you. And our next question comes from Asthika Goonewardene with Truist. Please go ahead.
Asthika Goonewardene
Hi guys. Good morning. Thanks for taking the questions. So the MIRASOL study, the ORR surprised just positively getting to the 40% plus range. And I guess one could attribute that to being the study recruiting a more for homogenous population than the Phase 1 and potentially a less sicker patient population than SORAYA. You guys have already said a very high bar with ORR in your Phase 1 expansion work. So would it be unreasonable to expect your ORR to look better on UPLIFT as well?
Anna Protopapas
Well, thanks for the question. We saw robust activities expansion cohort, particularly with the 36 milligram per meter squared. But I think the differences in overall response rate between MIRASOL and SORAYA do serve as a reminder that the type and level of patient pre-treatment can influence impact. And again, as Arvin mentioned on the call, we do have a population that is more heavily pretreated than SORAYA, indefinitely, even more heavily pretreated than MIRASOL. So I think we’ll have to wait and see the results midyear, but we’re confident based on the robust activity we saw in the expansion cohort.
Asthika Goonewardene
Great, thanks guys. And then maybe just a quick – two quick questions. Do you plan to report the UPGRADE-A data at a medical meeting or would that be more geared to its investment community? And then on the diagnostic test, our KOL checks suggested that there was some bottlenecks faced with the diagnostic test for mirvetuximab with one of the centers in particular take a little for while to turn the test around. What have you learned from that from the competitor’s experience and what are you doing to kind of make sure that you don’t run answer the same issues? Thanks.
Anna Protopapas
On the diagnostic, we’re working with our diagnostic partner to ensure that the test is available on day one and that we appropriately prepare in terms of supply of reagents to ensure there is no disruption in our availability of the test. And what was the other question? The other – was there a second question?
Arvin Yang
Yes, I can address the first question. Just as far as UPGRADE-A, we’ve indicated that we’ll share the data in the second half of this year. We haven’t expressed sort of what type of form that we’ll be in and we’ll disclose at the appropriate time.
Asthika Goonewardene
Thanks a lot guys.
Operator
Thank you. And our next question today comes from David Nierengarten with Wedbush Securities. Please go ahead.
David Nierengarten
Hey, maybe as a follow-up on the diagnostic or the testing question is, if – just if you had any particularly updated thoughts on how physicians would – when presented with a patient in an earlier lines or in, I guess, in any line of setting react to the patient, should they test with folate first? Are they going to do both tests? Do you think kind of how – and treat appropriately kind of how do you see that evolving with the positive MIRASOL results? Thanks.
Anna Protopapas
We are very encouraged by the testing that is teaching place with folate positive patients. And we believe that what will happen once both agents are in the market is that when a patient is diagnosed with ovarian cancer, they will undergo a set of tests that will include both folate and NaPi2b and that is the desired sort of state of affairs in the future. And I think the uptake we’ve seen on the following test is encouraging that that will be the case.
David Nierengarten
Got it.
Anna Protopapas
And David, we are definitely working to make sure that our test is available on day one after launch for anyone at any stage who wants to take the test at any stage of their disease.
David Nierengarten
Yes. Great. Thank you.
Operator
[Operator Instructions] Our next question is a follow-up from Colleen Kusy with Baird. Please go ahead.
Colleen Kusy
Hi, good morning, again. Thanks for taking the follow-up. Just one more, so on the UPLIFT readout and kind of understanding that the patient pre-treatment is going to impact the ORR, can you remind us how many patients in the dose expansion were fourth line or later. And would expect that proportion of patients to be similar or different in the UPLIFT study?
Arvin Yang
Thanks for the question, Colleen. So approximately 33% of the patients in the expansion portion of the Phase 1 study for UpRi was fourth line or later. Obviously, we’ll disclose the broader demographics at the top line per se. But for context, we enrolled in the U.S. as well as the EU for the UPLIFT study globally in relationship to the UPLIFT study. But we would expect practice patterns to be relatively similar in the platinum resistant space.
Anna Protopapas
Colleen, I would add one other point. The fact that we have enrolled so robustly in UPLIFT. I think might give us an opportunity to look at how pretreatment impacts overall response in subgroup analysis and really help us better understand the profile of the agent.
Colleen Kusy
Great. Thank you.
Operator
And ladies and gentlemen, this concludes our question-and-answer session. I’d like to turn the conference back over to Anna Protopapas for any closing remarks.
Anna Protopapas
Thank you, operator. And thanks to all those who listened in for our – and for your continued support. We’re looking forward to participating in the Bank of America Healthcare Conference tomorrow, sharing several poster presentations at ASCO next month and presenting at the Jeffries Healthcare Conference a few days later. Hope to see many of you at those events. Enjoy the rest of the day.
Operator
Thank you. Ladies and gentlemen, this concludes today’s conference call. We thank you all for attending today’s presentation. You may now disconnect your lines and have a wonderful day.
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