Ladies and gentlemen, thank you for standing by, and welcome to the Mersana First Quarter 2020 Earnings Conference Call. At this time, all participants’ lines are in a listen-only mode. After the speakers’ presentation, there will be a question-and-answer session. [Operator Instructions] Please be advised that today's conference is being recorded.

[Operator Instructions] I would now like to hand the conference over to your speaker today, Sarah Carmody, Executive Director, Investor Relations and Corporate Communications. Thank you. Please go ahead, ma’am..

Good morning. Welcome to Mersana's first quarter 2020 conference call. We issued a press release earlier this morning reviewing our first quarter 2020 results and business updates, which will be covered on this call. A replay of today's call will be available on the Investors and Media section of our website.

After our prepared remarks, we will open the call for Q&A. Before we begin, I'd like to mention that our call will contain forward-looking statements within the meaning of federal securities laws. These are not statements of historical facts and are based on management's beliefs and assumptions and on information currently available.

They are subject to risks and uncertainties that could cause the actual results and the implementation of the company's plans to vary materially, including the risk that our early encouraging preclinical results for XMT-1536 and XMT-1592 are not necessarily predictive of the results of our ongoing or future discovery programs or clinical studies; that the development and identification of our company's product candidates and new platforms will take longer and/or cost more than planned; and that our clinical trials will not be completed on schedule, if at all.

These risks are discussed in the company's SEC filings, including, without limitation, the company's annual report on Form 10-K filed on February 28, 2020 and subsequent filings.

In addition, while we expect that the COVID-19 pandemic might adversely affects the company's preclinical and clinical development efforts, business operations, and financial results.

The extent of the impact on the company's operations and the value of and market for the company's common stock will depend on the future developments that are highly uncertain and cannot be predicted with competence at this time.

Such as the ultimate duration of the pandemic, travel restrictions, quarantines, physical distancing and business closure requirements in the U.S. and in other countries and the effectiveness of actions taken globally to contain and treat the disease.

Except as required by law, the company assumes no obligation to update these forward-looking statements publicly, even if new information becomes available in the future. With that, I'll turn the call over to Anna Protopapas, Mersana's President and Chief Executive Officer..

Thank you, Sarah. Good morning, everyone, and welcome to our financial and corporate update call for the first quarter of 2020.

Joining me today with prepared remarks are Dirk Huebner, our Chief Medical Officer; Tim Lowinger, our Chief Science and Technology Officer; and Brian DeSchuytner, Senior VP of Finance and Product Strategy; Eva Jack, our Chief Business Officer; and Michael Kaufman, our Senior Vice President of Manufacturing are also available for your questions.

Since the beginning of 2020, we make great strides towards advancing our programs and executing against our key milestones.

Although the COVID-19 pandemic has impacted us and the world in unprecedented ways, we quickly adopted the way we do our work to ensure the safety of our employees and our patients while continuing to advance our key programs with a focus on delivering on our corporate goals and milestones.

I will provide a high level overview of what we have achieved this quarter and then Dirk, Tim and Brian will provide more details.

Before I begin, today is World Ovarian Cancer Day and I'd like to take a moment to recognize the women living with ovarian cancer, their families, and the many patient advocacy groups around the world promoting our awareness for this devastating disease. There remains a significant unmet medical need and limited treatment options for these women.

Today, we at Mersana reiterate a supported commitment to developing life-changing ADC therapeutics for those affected by ovarian cancer. With that, I would like to turn to the exciting data we recently presented from the Phase 1 dose escalation study of XMT-1536 in heavily pretreated patients with ovarian cancer and lung adenocarcinoma.

These data demonstrate that XMT-1536 has a favorable safety and tolerability profile without the severe neutropenia, neuropathy, or ocular toxicity seen with other ADCs. We saw confirmed responses and curable stable disease in heavily pretreated patients who have exhausted all other options and showed an emerging biomarker response relationship.

We also announced that we had reached the maximum tolerated dose at 43 milligrams per meter squared and are no longer enrolling patients to the dose escalation portion of the study.

Second, we remain on track to disclose early data from the ongoing expansion study of XMT-1536 and are very pleased to report that our abstract has been accepted for a poster session at the ASCO 2020 Virtual Annual Meeting to be held between May 29 and May 31.

In advance of the virtual ASCO poster session, we plan to hold a conference call and webcast to discuss this data on May 27 at 8:00 AM Eastern Standard Time. We will be joined on the call by Dr.

Debra Richardson, Associate Professor of Gynecologic Oncology at the Stephenson Cancer Center at the University of Oklahoma Health Care Center and the Sarah Cannon Research Institute. As we have indicated in the past, this interim disclosure of the expansion cohorts will be heavily skewed towards ovarian cancer.

Dirk will provide more details on the scope of our disclosure, but we believe we have accumulated meaningful patient experience to continue to support favorable safety and tolerability, a promising activity profile and to further establish a biomarker response relationship.

A third important milestone for us is initiating dosing of patients in the XMT-1592 Phase 1 dose escalation study in the first half of this year. We believe we're on track to achieve this goal and important first step in better understanding the potential clinical differentiation of XMT-1592.

A fourth set of goals is associated with our earliest stage pipeline. We remain on track to reach our ADC development candidate milestones this year. We have initiated IND-enabling studies with B7-H4 and are on track to disclose data on this candidate in the second half of the year.

In addition, we're continuing to advance our Immunosynthen platform and remain on track to select our first Immunosynthen candidate in the second half of the year. Finally, we added $65 million in gross proceeds through our ATM with participation based on interest received from Avoro, Bain Capital, Consonance Capital, and our Chairman, David Mott.

This strengthens our balance sheet and will be used to support our operations as we continue to advance our pipeline of innovative ADC candidates. With that overview, I would like to pass it on to the team who can give you more details on the progress we have made across all aspects of our business.

Let me turn the call over to Dirk first to discuss XMT-1536..

Thanks, Anna, and good morning, everyone. As Anna mentioned, we were very pleased to present positive data from the Phase 1 dose escalation study of XMT-1536 in heavily pretreated patients with ovarian cancer and NSCLC adenocarcinoma, two areas of significant unmet medical needs.

The cutoff date for this evaluation was February 3 and included 59 patients; 37 were ovarian cancer patients, 11 had NSCLC and the remainder were patients with more rare to most potentially expressing NaPi2b. I would now highlight the key findings of this study presented by our share of the safety review committee, Dr. Debra Richardson.

These data showed that XMT-1536 as well tolerated with all this severe toxicities of other ADC platforms such as neutropenia, peripheral neuropathy, or ocular toxicity. The most common treatment related adverse events were grade one and two, nausea, fatigue, headache, and the most frequent grade three treatment-related AE was transient AST elevation.

There were no dose limiting toxicities observed in the 43 milligram per square meter cohort. As a reminder, these were patients with a median of five prior lines of therapy and in most cases had run out of other treatment options.

Longitudinal studies have shown that as ovarian cancer patients progress the potential for response decreases rapidly with lines of therapy and that the expected response rate is close to zero for these ovarian cancer patients.

We saw further confirmed partial responses in ovarian cancer and our first confirmed partial response in an NSCLC adenocarcinoma patient. The fact that we saw confirm partial responses and durable stable disease in this patient population is very encouraging and supports further development of XMP-1536 in the ongoing dose expansion study.

In addition, a favorable biomarker response trend was observed.

For the subset of evaluable patients treated at 30 milligram per square meter and above who had high NaPi2b expression, five of 15 or 33% of patients received partial responses and six out of 15 or 40% of patients received stable diseases for a disease control rate of 11 out of 15 or 73%.

In contrast, there were no respondents in the low NaPi2b expressing group. This is important because it indicates the potential for patient selection strategy which can identify patients most likely to benefit from XMT-1536.

Before I move onto XMT-1536 dose expansion study, I’d like to remind that the first two patients in the 52 milligram per square meter dose escalation cohort experienced dose reductions which allows us now to declare the 43 milligram per square meter dose as the MTD for XMT-1536.

The dose escalation portion of the study is no close for new enrollments. As Anna mentioned, our XMT-1536 expansion extract was accepted by ASCO and will be presented on a conference call and in a poster session at the ASCO 2020 virtual meeting being held May 29 through 31.

The data will include safety, tolerability and efficacy for patients treated with 36 milligram per square meter and 43 milligram per square meter.

As a reminder, the expansion study, which was initiated at 36 milligram per square meter in August 2019 was later amended through enrolled patients at 43 milligram per square meter and continue to enroll patients at this dose level.

With a cutoff date of May 1, 2020, the presentation will include 20 RECIST-evaluable ovarian cancer patients and four RECIST-evaluable NSCLC patients. Biomarker expression data will be available for the majority of evaluable patients. Additional patients are enrolled in the study but have not yet reached the RECIST evaluation timepoint.

Given the limited duration of followup today, we do not expect to have mature data on duration of response. We expect to provide more information on durability of response when we report more mature data.

Remember that the ovarian cancer and lung adenocarcinoma patients being treated in the dose expansion study are still heavily pretreated and platinum resistant, but more homogeneous with one to three prior lines of therapy in ovarian cancer and some patients having four prior lines of therapy regardless of platinum status.

In NSCLC adenocarcinoma, patients have failed chemotherapy, PD-1 either alone or in combination [indiscernible] in oncogenic driver mutation HER-targeted therapy. Our goal is to enroll 40 patients to 45 patients in both ovarian cancer and NSCLC adenocarcinoma cohorts.

As we have said in he past, we believe the expansion cohorts would provide proof-of-concept for XMT-1536 and will allow us to chart a path to approval particularly in ovarian cancer where there is precedent [ph] for a single arm registration trial. I will now turn the call over to Tim Lowinger to discuss our research and development work..

Thanks, Dirk, and good morning, everyone. I will start with our first-in-class B7-H4 ADC development candidate. We're excited about the ADC target and believe it is well suited for the unique characteristics of our DolaLock payload and platforms.

We have compelling preclinical efficacy and nonhuman primate tolerability data with both Dolaflexin and Dolasynthen ADCs targeting B7-H4. Initiation of IND-enabling studies is ongoing and we recently initiated cell line development. We remain on track to disclose our development candidate and the supporting data in the second half of this year.

We've also continued to make important progress in our Immunosynthen platform design and the selection of our first STING-agonist ADC clinical candidate.

As a reminder, the goal of the Immunosynthen platform is to take ADCs beyond the traditional cytotoxic payloads to immunomodulatory payloads and preclinical studies show the potential to be safely and efficiently delivered to the tumor and stimulate an antitumor innate immune response.

We have a robust set of efficacy and tolerability, preclinical data across multiple targets and remain on track to finalize the Immunosynthen platform design and select our first STING-agonist ADC development candidate in the second half of 2020.

We're excited for the potential of this platform and believe that activating the innate immune system to fight cancer in a targeted manner is a potential game changer.

Before I turn the call over to Brian, I would like to note the last quarter we announced that we plan to present preclinical data on ADCs created with Dolasynthen and Immunosynthen platforms at the American Association for Cancer Research Annual Meeting.

Since that time, AACR has changed the meeting to virtual format and we will now be presenting this data as part of a virtual poster session scheduled for June 22, 2020. These data will include preclinical data from our work on XMT-1592, a Dolasynthen ADC targeting NaPi2b and our novel Immunosynthen STING-agonist ADC platform.

The abstracts outlining these data will be made available by AACR on May 15. We look forward to being able to share this exciting work. And with that, I will turn the call over to Brian DeSchuytner for an overview of our financial results..

Thank you, Tim. Good morning everyone, and thank you for joining us today. Today, I'll review some of the key financial highlights from our first quarter 2020 results and I'll start with our cash position.

We ended the first quarter of 2020 with approximately $78.4 million in cash, cash equivalents and marketable securities compared to approximately $100 million at the end of 2019. Net cash used in operating activities in the first quarter was $21.2 million compared to $24.7 million in the same period in 2019.

Net cash used in operating activities increased by approximately $9 million when compared to the fourth quarter of 2019 mainly due to the timing of compensation payments as well as the reduction on the accounts payable balance. As a reminder, in 2018, we set up At-the-Market or ATM financing facility in the amount of $75 million.

On April 7, we announced that we had raised gross proceeds of approximately $65 million through this facility with participation based on interest received from Avoro Capital Advisors, Bain Capital Life Sciences, Consonance Capital Investors and David Mott, Mersana’s Chairman of the Board.

Through this transaction, we sold approximately 8.9 million shares of the company's common stock at a purchase price of $5.59 and approximately 2 million shares at the closing price of $7.74, in each case the market price at the time of sale.

In addition, we had the option to draw additional funds of up to $15 million through the existing debt financing agreement with Silicon Valley Bank. Today, we are providing updated cash runway guidance following the ATM transaction.

We expect that our current cash, cash equivalents and marketable securities, including the proceeds from the ATM facility will enable us to fund our operating plan into early 2022. And now some of the key highlights from our first quarter 2020 financial results.

Collaboration revenue, in the first quarter of 2020 was immaterial when compared to the $41 million for the same period in 2019. This decrease in collaboration revenue was primarily as a result of the recognition of $40 million in deferred revenue in the first quarter of 2019 associated with the discontinuation of the partnership with Takeda.

Research and development expenses for the first quarter of 2020 were approximately $12.2 million, compared to $15.1 million for the same period in 2019.

The variance was primarily due to an upfront payment for a technology license fee in 2019 and the timing research efforts, the decrease in expenditures and supportive partner programs and a decrease in manufacturing costs for XMT-1536 and XMT-1522, all offset by an increase in XMT-536 clinical expenses as well as the advancement of the companion diagnostics development efforts for the NaPi2b biomarker.

General and administrative expenses for the first quarter of 2020 were approximately $4.9 million, compared to $4.4 million in the same period in 2019. A net loss for the first quarter of 2020 was $16.9 million, or $0.35 per share, compared to a net income of $21.9 million, or $0.72 per share, for the same period in 2019.

The difference was attributable of year-over-year was attributable to that $40 million in deferred revenue recognized in the first quarter of 2019. Weighted average common shares outstanding for the quarters ended 31st of March, 2020 and the 31st of March, 2019, were approximately 48 million and 30 million respectively.

Common shares outstanding as of May 5, 2020 were approximately 59 million. This count includes the shares issued in connection with the April ATM transaction as well as the exercise of approximately 2.6 million pre-funded warrants by BVF pursuant to the common stock exchange agreement signed in November, 2019. I will now turn the call back to Anna..

Thank you, Brian. The COVID-19 pandemic has brought challenges for all of us. I'm proud of Mersana team's commitment to science and patients and the team's ability to continue to execute on our goals in the midst of such a disruption.

I'd like to take a moment to discuss the impact of the pandemic and mitigation strategies we have put in place to reduce risk and ensure business continuity as best we can. First, and in line with guidance from the U.S.

Centers for Disease Control and Prevention and the state of Massachusetts, we have implemented work-from-home measures for all non-lab employees and have suspended all business travel. We have also implemented processes to ensure we continue to advance our ADC development candidates, while working to ensure the safety of our team.

While most of our lab employees also continue to work-from-home, we have prioritized lab activities that have implemented staggered schedules in the interest of safety and efficiency. We will continue to monitor the situation and continue to follow federal, state and local guidelines and directives.

From a clinical study perspective, the COVID-19 pandemic is a burden of all sites and hospitals in the U.S. and other countries, but cancer patients will always need treatment.

We have taken steps where possible for remote monitoring and remote testing consistent with FDA guidance and remain focused on ensuring the patients were benefiting, can continue their treatment. We have over 20 sites up and running with geographic diversity across the U.S.

These sites now have experienced with XMT-1536 and are excited about its potential benefit to patients and are continuing to enroll patients in the trial. Those screening of new patients has slowed down to some extent.

Additionally, we have plans to bring new sites up and some of those activities are ongoing, but certain sites have put initiation of new trials on temporary hold.

Lastly, on the manufacturing front, we have sufficient inventory of XMT-1536 and XMT-1592 to support ongoing and planned clinical studies as well as sufficient inventory of advanced intermediates stockpiled in the U.S. to support more than two years of manufacturing of drug substance and drug product.

Overall, we feel good about where we are on this front. Finally, before I turn the call over for questions, I would like to provide an update on our expected milestones for the rest of the year. I’ll start with XMT-1536.

As I mentioned, we remain on track to provide an interim look at the expansion study data on a conference call and webcast and in a virtual post session at ASCO in late May. We had previously guided to being able to provide a more mature look at this data in the second half of the year. Our objective is to continue to execute towards that goal.

If the COVID-19 disruption impacts our ability to deliver on that goal, we will provide guidance as appropriate. To reiterate non-small cell lung cancer, adenocarcinoma, enrollment continues to lag behind ovarian and this is likely to continue to be true in the context of the COVID-19 pandemic.

For XMT-1592 we remain on track and look forward to dosing patients in the second quarter of 2020. As for a pipeline development candidates, and as Tim said, we believe we're still on track to disclose our B7-H4 and STING ADC development candidates and the supporting data in the second half of this year.

Overall, we are in a good place from a business continuity standpoint. And I thank our employees for this and admire their continued dedication and drive as we all work together to get through these uncertain times.

We remain committed to achieving the milestones we laid out at the beginning of the year and reaching our overarching goal of significantly improving outcomes for people living with cancer. With that, I will turn the call over to the operator for Q&A..

[Operator Instructions] Our first question comes from the line of Jonathan Chang from SVB Leerink. Your line is now open..

Good morning and congrats on the progress. And thanks for taking the questions. First question, based on other data we’ve seen in the platinum-resistant ovarian cancer space, one could make the argument that an earlier line patient population activity should improve.

Would it be fair to have that expectation of your dose expansion data set compared to your dose escalation dataset? Why or why not?.

So thank you for the question, Jonathan. As we said before, the patients we are treating in the expansion cohort are still heavily pretreated patients, platinum-resistant patients with three, potentially four lines of therapy.

And as you know the standard of care there is single-agent chemotherapy, pegylated doxorubicin topotecan and the response rate there is pretty well established. The response rate for single agent chemotherapy is really no better than a 12% response rate [indiscernible] PFS.

As you recall from our dose escalations data, we've seen confirmed responses and prolonged stable disease in this very heavily pretreated patients, significantly later stage patients than what the expansion cohort population represents. So we've already achieved a significantly superior response rate in later stage patients.

And I think that establishes a level of activity that supports moving forward into registration, custom market registrations path. So could it get better with the early? Of course it could. But I don't necessarily think it has to have a meaningful drug that can really benefit patients and to have a path forward a faster market registration strategy..

Got it. Thank you. And just a second question, you indicate that the majority of the valuable patients from the expansion will have biomarker data.

I'm curious has your thinking around the prevalence of NaPi2b expression and potential, addressable population change with your experience in both the dose escalation and expansion?.

I'm sorry – Jonathan, can you repeat the question?.

Sure. You indicated that the majority of the valuable patients from the expansion will have biomarker data.

I'm curious if your thinking around prevalence of Napi2b expression and the potential, addressable population has changed with the experience you guys have had in a dose escalation and expansion portions?.

Yes, so as we've said we do not – we haven't really established a cutoff, although we are encouraged with the biomarker response data we are seeing. What we would like to do is get the totality of the data from all the patients in the expansion cohort and really use that to establish the cutoff.

That being said, we continue to be encouraged that we are seeing a good correlation and we continue to be encouraged that our understanding of the range of expression of NaPi2b in ovarian cancer patients remains consistent from the clinical experiences we did in all the work leading up to entering to the clinic, all the work we did with tissue samples.

And we feel we understand the broad expression..

Got it. Thank you..

Thank you. Our question comes from the line of Debjit Chattopadhyay from H.C. Wainwright. Your line is now open..

Hi, good morning everybody. Happy Friday. Congrats on all the progress. This is Earl DeSouza in for Debjit. Just a few questions from us.

Of the majority of the 20 patients that you will be presenting, would that be from the 36 milligram cohort? And I know you talked about it earlier during your remarks, but what is the length of follow-up of these patients? And a follow-up question would be – I guess my second question would be what kind of durability of disease control would convince you to head towards a single arm registration path? Thank you..

So thank you for the questions that Debjit [ph]. The durability really is – it really would depend on – and you can appreciate we have patients that have been on study for just a few weeks and we have patients that have been on study for six months or more.

So as we have said in the past the data the mature data will be disclosed in the second half of the year. It's a little premature to really determine the duration of treatment given that we have such a variation in time of all patients being on the trial.

As per your question about the mixture of 36 milligram and 43 milligram, I'd like to defer to my colleagues. Maybe Dirk has that answer..

Yes, this is Dirk. I welcome that question. As we said on the call the 36 mg/m2 dose cohort was started in August last year. And from that perspective, we’ve – certainly patients in that cohort we moved, started moving over to the 43 milligram in December.

So we have patients in both the 36 milligram and the 43 milligram that are available for assessment at the presentation. It's splits somewhat in half if you like. But of course because the 36 milligram patients are on study longer, you're going to have a little more duration on those patients compared to the 43 milligram..

Thank you..

Thank you. Our next question comes from the line of Boris Peaker from Cowen. Your line is now open..

Good morning. And I'd like to add my congratulations to the progress.

My first question is just curious as you enroll more patients and obviously in those dose expansion arms, at which point do you anticipate to be in a position with kind of adequate data in hand to discuss the regulatory path forward in ovarian cancer with the FDA?.

Great question Boris and one we are discussing internally. We had originally said and planned that we would recruit 40 to 45 patients. We thought that was a reasonable patient experience to make well informed decisions and have a really meaningful discussion with the FDA. Obviously as the data evolves, we're continuing to look at that.

But that was the plan and we remained on that plan at this point..

Great. And just my follow-up question, just logistically on the XMT-1536 study I'm curious, are these patients, are the majority of these patients being treated in the hospital or the outpatient setting? And how frequently do they need to show up to the facility? And how long do they stay at every treatment.

Dirk, I think, you might be able to better give an answer to that question..

Sure. Yes, no, it's an outpatient setting. So patients come in for dose administration and then what's usually happens after some collection of blood samples for different things for lab values, pharmacokinetic collection, et cetera. So that happens on the first day.

They come back on the second and third but they don't stay in the hospital and then we follow-up on a weekly schedule with those patients..

And just how long do they typically stay for each visit? Like with the infusion and all the assessment? I'm just curious..

Yes, the first day is a little longer that could be up to eight hours. The follow-up days would be would be shorter..

Great, thank you for taking my question..

You're welcome. Bye..

Thanks..

Thank you. Our next question comes from the line of Tom Shrader from BTIG. Your line is now open..

Good morning. Congratulations. Thanks for taking the call. I apologize if this is obvious to everyone else, but May 20, is that 20 are those all new patients? Remember there had been some dose – or some of the doses – some of the doses had been expanded the last time we saw data.

So is this all new patients?.

The 20 patients that are valuable on this study. A plenty of ovarian patients are part of the expansion cohort and they are all different patients than the ones we disclosed in the doses escalation..

Great, thank you. And then if I could, a good nerdy question for Tim on the Immunosynthen program, so much of the STING work has been dictated by direct tumor injection.

Do you expect to go after the same tumors that have been done before? Are there hints in the literature where STING might be exciting but you couldn't get to with non-systemic roots? Just your thoughts on whether you think there's low-hanging fruit in terms of tumor types for that kind of approach..

Sure. Tom I love the nerdy questions. I think we're very pleased with the progress we're seeing in our Immunosynthen STING agonist, ADC platform. And we look forward to disclosing the first candidate in the second half of this year. I think what I can say is that we have data now across multiple targets. So it's not just a single target.

And we think we have a very good understanding of what targets are appropriate and also which ones may not be. And so I think that's all I can really say today. But stay tuned in the second half we'll disclose the data..

That's helpful. Thank you..

Thank you. [Operator Instructions] Our next question comes from the line of Jessica Fye from J.P. Morgan. Your line is now open..

Hey guys, good morning. Thanks so much for taking my questions. Can you please set the stage for the ASCO abstract and help us think about the difference in the amount of information we'll get in the abstract relative to the full presentation, how many evaluable patients will be in the abstract and will we get safety there? Thank you..

Great question Jess, thanks for asking it. As you can appreciate the abstract was submitted in late January, early February. So I would guide you to look at it more as a place holder rather than anything else. The data really to look at is our disclosure on May 27, where we'll have the chance to really walk everyone through the full data set..

Okay, great. May be second question is sort of building on an earlier one, in the press release, you talk about the ASCO data reporting on the relationship between response and biomarker expression.

So when investors look at the response rate for 20 ovarian patients at ASCO, should we look at ORR across the overall group or should we be oriented to a subset of higher expressors?.

We will present both. And as we've said, we are – we haven't yet definitively defined the cutoff, but we are, as we get more data looking at that relationship and as we did in the dose escalation, we'll be able to share both the total population overall response rate as well as the response rate – the response biomarker relationship..

Great, thank you..

Thank you. Our next question comes from the line of Mike Ulz with Baird. Your line is now open..

Hi guys, thanks for taking the question. Congratulations on all the progress as well. Just had a question on XMT-1536. You mentioned enrollment and non-small cell lung is sort of lagging behind ovarian.

Can you just remind us that due to the timing of enrollment, were there other factors that might be driving that?.

Look, I think we've always said that enrollment in lung cancer was not moving as fast as ovarian. We started off with a lot more ovarian cancer patients in the dose escalation primarily because we focused on sites that had – that were primarily ovarian cancer recruiting sites.

Also with success we get more successes, so more responses in ovarian is accelerated, we could win in ovarian. We have seen increasing our experience with lung, but it's lagging behind. Other factors beyond just – relative body of data we have between ovarian and lung is that we are – lung is a more – there are more competitive trials in lung.

And we have a number of new sites that were planned to be up and running that we're focused on lung today, but have been partially delayed. We are still working towards bringing that recruitment up and believe we are on track to recruit the 40 patients we want in the extension cohorts this year. But we're continuing to monitor this situation.

And if that changes, we will let you know..

Got it. That's helpful. And then maybe just another question on XMT-1592. So, you're still on track to start your Phase 1 study this quarter. So could you just talk about the study design there and maybe your dosing strategy as well? Thanks.

Yes, we will be recruiting – our objective in the dose escalation is move through dose escalation as quickly as possible. We will be recruiting both lung and ovarian cancer patients because that's the way we can move through dose escalation as quickly as possible. And the first few doses are single patient dose cohorts.

And as we initiate the trial and start dosing patients we’ll be able to share more information with you about that trial..

Got it. Thank you..

Thank you. Our next question comes from the line of David Nierengarten from Wedbush Securities. Your line is now open..

Thanks. I just have a quick question. Will, there be – I understand it's difficult to pay any opportunity to see longitudinal bio marker data over time if you have archival samples and comparing them to fresh samples for the ovarian cancer – or any of the patients? Just a question on that ASCO presentation. Thanks..

Yes, it will not be part of the ASCO presentation..

Okay..

And at this point it's not part of the protocol to get paired biopsies from patients we’re treating. That's something we might embark on in the future, but it's not part of the current protocols..

Okay, understood. Thank you..

Thank you. At this time, I am showing no further questions. I would like to turn the call back over to Anna Protopapas, President and CEO for closing remarks..

I want to thank everyone for participating on the call. We are very excited to have the opportunity to share with you the expansion cohort data in a few weeks and look forward to talking to you again at that time..

Ladies and gentlemen, this concludes today's conference call. Thank you for participating. You may now disconnect..