Aptinyx Inc. (APTX) Q4 2021 Earnings Call Transcript

Aptinyx Inc. (APTX)
Q4 2021 Earnings Call
Mar 23, 2022, 5:00 p.m. ET

Contents:

• Prepared Remarks
• Questions and Answers
• Call Participants

Prepared Remarks:

Operator

Good afternoon, and welcome to the Aptinyx fourth quarter and year-end 2021 financial results conference call. At this time, all participants are on a listen-only mode. Following the formal remarks, we will open up the call for your questions. Please be advised the call is being recorded at the company's request.

At this time, I would like to turn the call over to Pat Flavin, senior manager of corporate development and investor relations at Aptinyx. Pat, please proceed. 

Pat Flavin -- Senior Manager, Corporate Development, and Investor Relations

Good afternoon, everyone, and thank you for joining us on today's conference call to discuss Aptinyx's fourth quarter and year-end 2021 financial and operating results. We invite you to visit the Investors section of the Aptinyx website to view our press release describing financial results and business highlights. On today's call, Andy Kidd, our president and chief executive officer, will discuss our business and clinical development progress; then Ashish Khanna, our chief financial officer and chief business officer, will review our financial results. I would like to remind everyone that statements made during this conference call will include forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties that can cause actual results to differ materially.

Any forward-looking statements are made only as of today, and we disclaim any obligation to update these forward-looking statements. Please see the forward-looking statements disclaimer in our financial results release issued this afternoon and the risk factors in the company's current and subsequent filings with the SEC. It's now my pleasure to turn the call over to Andy. 

Andy Kidd -- President and Chief Operating Officer

Thank you, Pat, and good afternoon, everyone. We appreciate you joining us on today's call. 2021 marked a year of significant progress for Aptinyx. Our mission is to develop transformative therapies for challenging disorders of the brain and nervous system, and over the course of the past year, we've taken major strides toward that goal.

We are on track for a series of catalytic milestones and data readouts across our pipeline of NMDA receptor positive allosteric modulators and expect that 2022 will be a pivotal year for the company. In the next few months, we expect readouts from our two phase 2b studies in chronic pain with NYX-2925 starting with diabetic peripheral neuropathy, or DPN, data very shortly in April. The fibromyalgia data is then expected in the July to August time frame. In addition, we expect the readout from our exploratory study of NYX-458 in cognitive impairment associated with Parkinson's disease and dementia with Lewy bodies within the next 12 months.

Finally, we've been initiating two phase 2b studies with NYX-783 in PTSD and expect data from those studies starting in the second half of next year. We're supported by a balance sheet that fuels these development programs and is expected to provide operational runway well into 2023. Let's discuss our clinical development programs in more detail beginning with NYX-2925 in chronic pain. As I mentioned, each of our chronic pain indications, DPN and fibromyalgia, will read out in the next few months.

Despite a challenging external environment throughout 2020 and 2021, our phase 2b study in DPN completed enrollment well within schedule last October. With a 12-week treatment period and 30-day follow-up, we've completed last patient last visit and are expecting to receive and communicate data during April. The study design integrates several key lessons from our prior phase 2a study in DPN that read out in 2019. Firstly, we're focusing on a patient population with four years or more of DPN disease duration.

We observed a stronger response in patients with longer disease duration in our prior study. We believe this is because the abnormalities in pain processing within the prefrontal cortex of the brain that our mechanism targets take time to become -- manifest. In addition, we are assessing NYX-2925 as a monotherapy without any concomitant analgesics and with a 12-month treatment period. We expect these design choices will increase the chances of separation from placebo and are in line with regulatory requirements for approval.

The DPN study evaluates 12 weeks of daily dosing with 50 milligrams of NYX-2925 or placebo. And the primary endpoint is the change from baseline to week 12 in patient-reported average daily pain, averaged over a week and evaluated using the zero to 10 Numeric Rating Scale, or NRS. The study is powered to detect an effect size that is clinically meaningful. Depending on the degree of variation seen with pain score differences, the lower bound of what is needed to achieve statistical significance would be somewhere between a 0.5 and 0.7 difference between NYX-2925 and placebo on the zero to 10 NRS scale.

Next steps following this study would include an end of phase 2 meeting with FDA to discuss requirements for phase 3 and NDA. Our phase 2b study in fibromyalgia completed enrollment at the end of February, and so it was just a few months behind our time line for DPN. We expect to have data reading out in July or August. This phase 2b study in fibromyalgia is similar in design to our DPN study.

It evaluates NYX-2925 as a monotherapy with no concomitant analgesics and with a 12-week treatment period. The primary endpoint is the change from baseline to week 12 in patient-reported average daily pain averaged over a week and evaluated using the zero to 10 NRS. In this study, as well as the 50-milligram dose, we're also evaluating a 100-milligram dose since we saw promising effects with a higher dose level in a prior neuroimaging study in fibromyalgia. We believe, based on this neuroimaging study and the underlying disease biology, that the abnormalities in pain processing within the prefrontal cortex of the brain that our mechanism targets are present in fibromyalgia at the start of the condition.

We, therefore, do not have a disease duration requirement as we do for DPN. The study is powered in a similar way to the DPN study, and the next steps would include meeting with FDA to determine the requirements for phase 3 and NDA. If both programs advance into phase 3, we expect there will be synergies in clinical safety and nonclinical development work between the two. We would also consider further indication expansion with chronic pain as there are a number of other neuropathic pain conditions and musculoskeletal pain conditions in which we think our mechanism is relevant.

Finally, we expect the positive data in one or both of these studies would unlock very significant value for Aptinyx. The clinical unmet need in chronic pain is substantial. A drug with evidence of efficacy and a strong safety profile will have a potential commercial opportunity well into the billions of dollars of annual sales in the U.S. market alone.

Next, we'll discuss NYX-783, our product candidate in development for the treatment of posttraumatic stress disorder, or PTSD. In December, we commenced phase 2b development of NYX-783 in patients with PTSD with the first of two phase 2b studies. In the first phase 2b study, approximately 300 patients with PTSD will be randomized to placebo or 50 milligrams of NYX-783 and evaluated over a 10-week treatment period. We anticipate reporting data from the first phase 2b study of NYX-783 in the second half of 2023.

The second phase 2b study has the same design as the first, except that it will test a 150-milligram dose level of NYX-783. This dose has not been tested in patients before, but based on recent preclinical data, we think there's potential for this higher dose to be effective. We have been planning to initiate the 150-milligram phase 2b during Q1. We've completed all of the operational steps required, but as we've worked to activate the first group of sites, we now expect to begin screening patients in April.

The two-study approach in PTSD is among a range of measures we're employing to minimize and mitigate the placebo response and variability during phase 2b. Having two studies for two different dose levels limits the number of arms per study, a factor which is correlated with lower placebo effects. In addition, two studies limit the number of sites and clinical investigators per arm, which should help to control the variance in measuring clinician-assessed endpoints. We're also not allowing concomitant PTSD pharmacotherapies in either of these studies.

Finally, let's discuss NYX-458 in cognitive impairment. We're currently evaluating NYX-458 in an exploratory phase 2 study of cognitive impairment associated with Parkinson's disease and dementia with Lewy bodies. This double-blind placebo-controlled study evaluates a 30-milligram dose of NYX-458 versus placebo in approximately 100 patients over 12 weeks of treatment. This is our first study in patients with cognitive impairment and is primarily meant to detect and characterize signals of activity.

As well as safety and tolerability, we are evaluating the effects of NYX-458 across a battery of neurocognitive tests able to measure changes in attention, memory, and executive function. These cognitive domains are impacted in Parkinson's disease and dementia with Lewy bodies and our NMDA receptor-dependent phenomena. As we mentioned during our Portfolio Day in February, we did see a slowdown in clinical trial enrollment in the U.S. after Thanksgiving and continuing into January, at least partially related to the omicron variant of COVID.

We've seen activity return to normal since then, and we still expect to be able to read out data from this study late in the fourth quarter of 2022 or in the first quarter of 2023. In addition to the progress we've made in advancing our pipeline, we recently hosted a Portfolio Day for investors on February 9. This included a review of the chronic pain treatment landscape by Dr. Richard Rauck, a board-certified physician in pain medicine and anesthesiology with the Carolinas Pain Institute and an investigator in our DPN study.

This event is available for review on our website. We also announced the formation of a Scientific Advisory Board comprising leading researchers and physicians in the areas of neuropsychiatry, neurology, and chronic pain, including Chadi Abdallah, MD, from Baylor College of Medicine; Lesley Arnold, MD, from the University of Cincinnati College of Medicine; Peter LeWitt, MD, from Wayne State University School of Medicine; and Jerry Sanacora, MD, Ph.D., from Yale University School of Medicine. The Scientific Advisory Board will work closely with us to establish scientific and clinical input as we advance our pipeline. Before I hand over to Ashish to review our fourth quarter and year-end 2021 financials, I'd like to take a moment to acknowledge and thank our Aptinyx employees and our external partners for their tireless work over the past year.

We have fewer than 40 internal employees who have successfully managed the ever-fluctuating external landscape, working closely with multiple external partners, vendors, clinical trial sites, and investigators in challenging circumstances. This has been a difficult time for clinical trial sites and, of course, for patients, and we're very appreciative to all of those who have contributed to our clinical research efforts. It is only because of the dedicated efforts in the service of our mission to patients that we've been able to advance our pipeline to this critical point and are able to look forward to the data readouts that we expect both in the next few months and over the next two years. Ashish? 

Ashish Khanna -- Chief Financial Officer and Chief Business Officer

Thank you, Andy. Beginning with the balance sheet. We ended the fourth quarter of 2021 with $106 million in cash and cash equivalents compared to $141 million at the end of 2020. That year-end 2021 cash figure does not include $10 million from the second tranche of our capital credit facility, which we drew down earlier this month and reported today in our 10-K filing.

With respect to our income statement, as expected, we had zero revenue in the fourth quarters of both 2021 and 2020. We did have $1 million in revenue over the full year 2021 as compared to $1.6 million in revenue for the full year 2020. In both of those years, the revenues were related to our research collaboration agreement with Allergan, now a subsidiary of AbbVie. That research collaboration came to its contractual conclusion early in 2021, and we have not been reliant on it or any other source of income to fund our operations.

The majority of our spend remains heavily concentrated in research and development. R&D expenses totaled $14.1 million and $55.4 million for the fourth quarter and full year 2021, respectively, as compared to $6.8 million and $32.8 million for the same period in 2021. The rise in R&D expenses in 2021 was primarily driven by increased spending related to clinical development across each of our phase 2 programs during the year. This followed a period in 2020, during which we temporarily paused patient enrollment in three of our four then ongoing phase 2 studies, contributing to less-than-expected R&D spend during that year.

We reported G&A expenses of $5.1 million and $20.1 million for the fourth quarter and full year 2021, respectively, as compared to $4.8 million and $19.5 million for the same periods in 2020. Finally, we reported a net loss of $19.6 million and $74.9 million for the fourth quarter and full year 2021, respectively, as compared to a net loss of $11.5 million and $50.1 million for the same periods in 2020. So I'll now turn the call back over to Andy. 

Andy Kidd -- President and Chief Operating Officer

Thanks, Ashish. As we approach a steady cadence of important data readouts, the first of which is expected in the next few weeks, we look forward to moving into our next stage of growth as a company. We're pleased to be well-positioned both financially and operationally to continue to advance our pipeline toward the patients that desperately need better therapies. We are happy to begin taking your questions now. 

Questions & Answers:

Operator

Thank you. [Operator instructions] The first question comes from Chris Raymond with Piper Sandler. Please proceed.

Chris Raymond -- Piper Sandler -- Analyst

Hey, thanks for taking the question. I just have maybe one and then one follow-up. So I guess just guys, on the 2925 data, you obviously have the DPN data coming first. That's next month.

And then the fibromyalgia data, obviously, I think you said, Andy, it's now July or August. So I think this question has come up before, but I just want to maybe ask it again since we're so close here to these events. These are obviously different disease states, but there are similarities, I guess, in terms of the clinical measure with NRS and what's considered clinically relevant. Maybe just frame for us the differences between these two programs and why maybe or why not investors should see the outcome in DPN as a direct read-through to fibromyalgia.

Andy Kidd -- President and Chief Operating Officer

Yeah. Thanks, Chris. It's a great question. Fortunately, probably one that will have a limited shelf life because, as you pointed out, the gap between the data from the two studies is about three or four months, and so we will know the answer before too long.

But I think it would be helpful to frame out, as you suggested, the key differences and similarities. We, of course, think there will be some read-through, but we do not think it's an absolute read-through. There are some important differences. I think the main difference between the two conditions really is that, obviously, DPN begins as a peripheral neuropathic condition.

In fact, it's classified by FDA -- or classified in their chronic pain guidance as a peripheral neuropathy. It clearly starts with nerve damage in the periphery. And as I mentioned in my remarks, the kinds of centralization of pain processing abnormalities that our mechanism targets take a while to become established in DPN, whereas in fibromyalgia, based on imaging and based on studies that have been done by others in the disease state, we think that those central pain processing abnormalities kind of characterize the condition or an inherent part of the condition. So there's some different underlying biology.

Of course, we've tried to take account of that with the study design, but nonetheless, different underlying biology. There's also different extent to which I think our precedent data inform specific elements such as dose. We think we have good clinical proof of concept in both indications. But obviously, we're looking at two different doses in fibromyalgia versus one in DPN.

So I think those are a couple of reasons why both biology and dosing-wise, there's less than 100% read-through between the two indications, substantially less, I think I would say. But clearly, on the similarity side, as you mentioned, some of the study design elements are very similar. And also, of course, ultimately, our drug is, we think, acting in the prefrontal cortex to establish a better modulation of abnormal pain in the brain. So there's a clear similarity with which part of the brain we're targeting.

So, yeah, I think as we've consistently said, we believe there is read-through, but we do not believe there is complete read-through. There is still a reasonable amount of independence between the risk in these two indications. 

Chris Raymond -- Piper Sandler -- Analyst

Thank you for that. And maybe just a quick follow-up. Andy, I think you highlighted with the timelines section in your prepared comments, I think I heard 458, the cognitive impairment data could now slip into next year. Can you maybe put some color on that? What's the driver for that? I think the last update, it was an end-of-year thing or maybe I'm misreading.

Andy Kidd -- President and Chief Operating Officer

OK. So, Chris, that's partially right. I think in our last quarterly call, we were saying end of year. When we did our Portfolio Day in February and kind of updated across the pipeline, we provided a modification to still potentially possible by end of year but may move into Q1 as well.

So I think it's somewhere between the two right now. The reason for that, that we outlined this at Portfolio Day, and I've already briefly recapped it in my remarks today, but I can explain it more, is we saw, and probably not surprisingly, after Thanksgiving as the omicron wave started to take effect in the U.S., sort of broader environment, we did start to see a slowdown in enrollment. Now you often see a slowdown in enrollment in clinical trials over the holidays anyway. We do think it was exacerbated a little bit by omicron potentially affecting patients' willingness to enroll in studies but potentially also, we know in some cases, affecting clinical trial sites, of course, had issues with staff having to quarantine or isolate and so on.

We're tracking that, of course, through January. And when we did the Portfolio Day in February, we provided the update. I think as I mentioned, since then, it looks as though enrollment has returned back to its prior level. And so I think we're now still comfortable to guide that, that slowdown caused the delay but there's not an ever-increasing delay.

So, therefore, we would expect to have data again potentially by the end of this year or into Q1 of next year.

Chris Raymond -- Piper Sandler -- Analyst

Got it. Thank you.

Operator

Thank you, Chris. The next question comes from Charles Duncan with Cantor Fitzgerald. Please proceed.

Charles Duncan -- Cantor Fitzgerald -- Analyst

Hi. Yeah, good afternoon, Andy and Ashish and team. Congratulations on the progress in the chronic pain programs. Looking forward to seeing that data soon.

I had a couple of questions on 2925 in DPN. And in particular, I just wondered if you could frame for us a little bit of perspective on what a 0.5 to 0.7 NRS difference means in terms of clinical meaningfulness, in terms of your feedback from investigators and clinicians. 

Andy Kidd -- President and Chief Operating Officer

Yeah. Certainly, Charles. So when we talk to clinicians about what is clinically meaningful in pain studies or chronic pain studies in general, I think it is a little bit of a complicated question, and they have a couple of different ways of thinking about it. So on the one hand, a lot of times, some people are asking -- they're trying to get at what you just described, which is what degree of separation between active and placebo is considered meaningful.

I think that generally comes in the range that we just described of 0.5 to 0.7 or higher would be clinically meaningful. I would say that a lot of pain clinicians, and Richard Rauck, who was on our Portfolio Day was one of them, would say, I really want to be convinced that the drug is not the same as placebo. I want to see statistical significance in the separation, some margin, but I'm not too focused on actually exactly what that is because I really -- because I know that the clinical study environment is an artificial environment. We know that placebo effects are a significant issue.

And I think in addition, the field now generally views placebo and drug effects as not always purely additive but actually potentially somewhat overlapping phenomena. And so that sort of tends to be the answer on separation. When you then talk about other indicators of clinical meaningfulness, they will say, what I would look at generally if I'm deciding whether to get this drug to a patient is the reduction from baseline since that's what the patients will experience in the real world. And then potentially also, as you're considering a population or what are my go-to therapies that I will prescribe frequently, what's the expected response rate for a given amount of pain reduction, and 30% is a threshold that's commonly used.

What percentage of my patients would I expect to see getting a 30% or so reduction in pain? And I think those two measures have changed from baseline on average, and then the responder rate are put in the context of the safety and tolerability profile and, of course, the better the safety and tolerability profile, the more probably margin there is or potentially lower the bar would be for clinical meaningfulness on the efficacy side because there are so few options out there that provide a good risk-benefit profile to a lot of these patients. So it gets a little more nuanced. And I think that our sense as we look at the data will be it's important to show separation from placebo, but there is also some focus in the real world on the magnitude of response and the consistency of the response.

Charles Duncan -- Cantor Fitzgerald -- Analyst

OK. And response rates, it sounds like. And then second question regarding -- and this kind of points to next steps, but just regarding the definition of the period for chronification or centralizing the pain being four years. I'm sure it's not a hard point in time.

Maybe three-year patients have that as well. But how did you define that? How do you practically define that in terms of symptom presentation? How do you ensure that the majority of your patients have had sufficient time to see centralization of the pain? Is it through a prescribing pattern? Or how is it done in this trial? And how would you anticipate it going forward? 

Andy Kidd -- President and Chief Operating Officer

It's quite a tricky question, Charles. There have been a lot of people who have tried to use clinical measures to characterize the centralization of pain. And of course, there are some symptoms like hypersensitivity to pain, allodynia and so on that should be characteristic of centralized pain. It tends to be a little difficult though using kind of real pain measurement instruments to come up with good consistent screening approaches.

So we don't have a lot to work with there. I think, in addition, there's a better characterized time frame for some kinds of centralization. The sort of amplification of pain in the spinal cord, for example, it might start to happen around six months. But for the kind of chronic pain that we're -- or chronification of pain that we're looking at involving the corticolimbic parts of the brain, including the prefrontal cortex, it may be that that takes longer than the changes than the spinal cord do.

It's not an area that's been extensively studied. So I think we are trying to advance the two ideas in parallel. So on the one hand, in the study, we're really just using duration of disease. And of course, patients have to have enough pain -- enough magnitude of pain to get into the study.

And then I think in parallel, working with our Scientific Advisory Board, working with others to try to clarify and advance the understanding of exactly what there could be that is a sign of the prefrontal cortex type of function that our mechanism can work against. And it's not just using the passage of time as a way to try to get to those patients. So it's a little bit of a work in process. And it has, I think, for the field in general, have been a relatively difficult area to produce a clear or a measurable biomarker or something of that nature. 

Charles Duncan -- Cantor Fitzgerald -- Analyst

Yeah, but it's a really interesting hypothesis. Last question in terms of next steps. Could you imagine that this particular phase 2b could be one of two potential pivotal studies? Or would you anticipate wanting or needing to conduct two additional pivotal studies should the data readout cleanly and you move forward in DPN? 

Andy Kidd -- President and Chief Operating Officer

It's certainly, I think, possible that this data could serve as pivotal. The study, we did design trying to follow as far as we could the requirements that have been previously laid out by FDA for chronic pain. However, we didn't meet with FDA in advance to clarify or confirm that. So I would say it is a possibility.

We consider it really an upside scenario. And even if it doesn't turn out to be the case that this could serve as a pivotal, it will certainly give us a very good guide as we design our pivotal since we'd expect, again, the design to follow very closely our phase 3. 

Charles Duncan -- Cantor Fitzgerald -- Analyst

Perfect. Thanks for taking my questions. Good luck with the upcoming data.

Andy Kidd -- President and Chief Operating Officer

Thanks, Charles.

Operator

Thank you, Charles. The next question comes from Ritu Baral with Cowen. Please proceed.

Ritu Baral -- Cowen and Company -- Analyst

Hi, guys. Thanks for taking the question. On the fibromyalgia trial, Andy, you mentioned you're looking at the 50 and the 150 and that the statistical analysis plan was otherwise very similar to the DPN study that's going to be reading out next month. Can you talk about, I guess, the primary analysis between the 50 and the 150 in fibromyalgia? Is it going to be sort of a blended analysis versus placebo? Or are you taking two looks and taking an alpha hit between the two doses?

Andy Kidd -- President and Chief Operating Officer

Thanks, Ritu. Yeah. So fibromyalgia, I think it's 50 and 100 are the two doses. The 150 is for PTSD.

So -- that's fine. So yes, so 50 and 100. Look, I don't think at this stage, we really want to get into too much detail in our statistical analysis plan. I think it is certainly all prespecified and clearly laid out.

I guess as a main objective, I would say we are interested to see which of these two doses performs better with a view to then what would our strategy be in phase 3. So I think I'll just restrict my comments there. I wouldn't expect anything out of the ordinary, and everything certainly will be very clearly prespecified in our SAP. We're just not sharing too many details about the SAP right now.

Ritu Baral -- Cowen and Company -- Analyst

OK. And then you made a very intriguing comment about other pain conditions that you're considering with unmet need with rationale. Can you talk about some of those conditions that you're at least considering, especially the ones that have rationale around NMDA modulation?

Andy Kidd -- President and Chief Operating Officer

Yeah, absolutely. So a lot of pain conditions will have a rationale based on simply the experience of prolonged pain, causing some of these chronic abnormalities. So it is a fairly wide-open field. I think that we will be looking at the data from these two indications to try to help us prioritize.

Certainly, there are other types of neuropathy that we're very interested in, and we have conducted preclinical studies and published preclinical data in some of those, in particular, in chemotherapy-induced neuropathic pain where we published the clinical data in the last year or two. And I think on the musculoskeletal side, we are certainly interested in a range of different conditions, including osteoarthritis and so on. I think where we go and how we prioritize those indications will be driven somewhat by the data that we see in these two studies.

Ritu Baral -- Cowen and Company -- Analyst

Got it. And very last quick question. Is there anything significant in the delay in screening start for the 150-milligram PTSD study? Was that COVID-related? Were there any IRB issues, etc.? 

Andy Kidd -- President and Chief Operating Officer

Yeah. Thanks, Ritu. No, there weren't IRB issues. But again, like I said, we actually had everything in place on our side and with the key external partners to operationally be ready.

It really was just driven by taking not very much longer, obviously, just a few weeks longer to get the first wave of sites initiated and up and running. It's hard to tell, to your question, what is the COVID-related delay at this point because, as I mentioned, COVID has impacted clinical study sites from particularly a staffing point of view. And so there is that as a backdrop to everything. I think there is, in the U.S., obviously, a reasonable amount of other studies.

And that's a change from a few years ago and I think a welcome one because it shows a much greater attention on PTSD and many other therapies that are being developed. But there are a few more studies out there. And so it just means that the process of prioritizing the sites is a little bit more complex because there's a few other studies out there. So probably a combination of those things, not really a very significant delay, we don't think, and we look forward to getting up and running and screening in the next few weeks.

Ritu Baral -- Cowen and Company -- Analyst

Great. Thanks for taking all the questions.

Andy Kidd -- President and Chief Operating Officer

Thanks, Ritu.

Operator

Thank you, Ritu. The next question comes from Gary Nachman with BMO. Please proceed.

Gary Nachman -- BMO Capital Markets -- Analyst

OK. Thanks, guys. Also on 2925, will you have two separate end-of-phase 2 meetings for each of the indications in DPN and fibro? Or will it make more sense for them to be considered together when planning the phase 3 program? And if both fibro doses, the 50- and the 100-milligram, show efficacy or the 100-milligram is better, since DPN is just 50, would that complicate going for a single chronic pain indication with 2925?

Andy Kidd -- President and Chief Operating Officer

Yeah. Thanks, Gary. So on the first point around the meeting, we're planning right now to have two separate FDA interactions. We think it probably makes more sense to keep moving with DPN as opposed to waiting for fibro data.

Given the likely timing of FDA meetings and fibro data though, we certainly wouldn't anticipate kicking off a DPN study before we had seen the fibro data and would be able to make sure if there were or if there was anything that would inform the protocol that there would be time to incorporate that. So I certainly wouldn't take away from that, that we'll be rushing too far ahead with DPN. But we do think it makes sense to meet separately and capture a little bit of the timing upside on DPN. With respect to the ultimate question of label and dosing, it's difficult to say.

I think that would be a question to discuss with FDA. I would say the past broader label is something that we would like to clarify with FDA. It was, we believe, one of the reasons why the prior chronic pain drug development guidance was actually pulled back. Not many sponsors had availed themselves of the framework that was in that guidance for achieving broader label language.

And it's possible that there's some different thinking that FDA has on that. And I think it would be difficult to comment on whether different doses being optimally effective in different indications would be any kind of a challenge there. I'm not sure I would foresee that being a challenge, but I think that whole question would be something that we'll discuss with FDA.

Gary Nachman -- BMO Capital Markets -- Analyst

OK. Great. And then for 458 in cognitive impairment, what do you think the rough split will be on the 100 patients between Parkinson's and Lewy body dementia? I know you've been asked that in the past, but maybe what you're thinking at this point. And any issues from COVID with those patients in either patient group? And then just explain a little bit more what you're hoping to show on the efficacy side in terms of what kind of signal we might be able to see. 

Andy Kidd -- President and Chief Operating Officer

Yeah. Thanks, Gary. So I think on the split, we don't have a very specific preformed goal around that split. And in terms of the expectations, it depends a little bit.

You can look at the different prevalence, but you also then have to consider who's likely to step forward and participate in a clinical trial and then pass the inclusion/exclusion criteria. So other than saying I think we would certainly hope that there is a reasonable representation of all of the different groups of patients, and that's Parkinson's and CI, Parkinson's dementia and dementia with Lewy bodies, I wouldn't go any further right now in terms of particular or specific expectations there. With respect to COVID potentially making a difference, yes, I think like I mentioned, there was a little bit of a slowdown, it looked like, in enrollment with omicron wave over December and January. It's a little difficult for us to tell exactly how much of that has really to do with patient behavior though versus the sites that also have issues with site stopping, as I mentioned.

We've generally been a little -- we're cautious in restarting the study, and it didn't restart it until after the vaccine rollout in 2021 to more vulnerable populations, including obviously those over the age of 65. The age range in the study is 55 to 85, but the majority of the subjects we'd expect would be toward the higher end of that range. And so we've, I think, generally been sensitive to that and how we've set up the protocol and tried to make the site/patient interactions as efficient as possible. And we haven't had, I think, any sense that there's an issue that -- patients are willing to take part in the study.

And other than that slight slowdown over the holidays, it seems to be going well. In terms of the efficacy signal, yes, the efficacy endpoints that we'll be paying the most attention to are a series of six different neurocognitive tests, things like the Groton Maze, the two-back test, the International Shopping List and so on. Those are fairly well known, have been used in cognitive studies quite widely, and are targeted of measuring different domains, executive function, working memory, and attention, in particular, that are known to be NMDA-dependent phenomena, also characterized as types of cognitive impairment you see in Parkinson's disease. And I think we're really looking on those different tests for a signature of how does this drug improve cognitive performance in these patients and see what that profile looks like.

And I think that will then help us as we move forward into phase 2b and phase 3 studies as we're trying to select the right endpoints, which we'll need for those studies, which will have to be more straightforward, easy-to-implement cognitive tests, and also probably some measures of function. And we can come to the recommendation on how to do that based on the profile that we see with these more sensitive, more specific neurocognitive tests.

Gary Nachman -- BMO Capital Markets -- Analyst

OK. That's helpful. And just last quick one for Ashish. How much more flexibility do you have to tap into the credit facility with K2? How much is left on it after taking down the last $10 million? Thanks.

Ashish Khanna -- Chief Financial Officer and Chief Business Officer

Yeah. Thanks, Gary. So the entire facility was $50 million. The first tranche we took down shortly after signing, $15 million.

We've taken down in March, as I noted, another $10 million. That leaves $25 million that would be accessible upon positive data milestones and mutual agreement with the lender. 

Gary Nachman -- BMO Capital Markets -- Analyst

OK, great. Thank you.

Operator

Thank you, Gary. The next question comes from Marc Goodman with SVB Leerink. Please proceed.

Unknown speaker

Hey, thanks for taking my questions. It's Rudy on the line for Marc. So I have a question regarding NYX-458. So there are several other NMDA products entering mid-stage studies for cognitive impairment.

Can you remind us about NYX-458 current evidence to support its efficacy in this indication? And how could these products be differentiated versus other NMDA products? And secondly, can you remind us the discontinuation rate so far in ongoing DPN trial? Are there any new safety signal that you observed? 

Andy Kidd -- President and Chief Operating Officer

OK. Great. Thank you. Yeah.

So let's start with 458. So the evidence for efficacy we have here, of course, so far is all preclinical. We're in our first inpatient study right now. The most, I think, interesting piece of preclinical evidence that we have is from a study in nonhuman primates using a neurotoxin called MPTP to create a cognitive deficit that is caused by dopaminergic cell depletion and so very similar to what is seen in Parkinson's disease.

And in that study, we saw a marked and sustained cognitive deficit that was created by this neurotoxin, but it was largely very rapidly reversed by just a single dose of NYX-458 that's across a range of different measures of cognitive performance. And the improvement was sustained actually for a few weeks before returning back to the impairment level. So it was very encouraging, very exciting preclinical data. We also had some data from rodent models of various different kinds, but that was probably the most translatable preclinical data.

So we were very excited to take the drug into the clinic. We did decide, and it was a conscious decision, that our first study in patients would be a robustly designed, double-blind, randomized, placebo-controlled study of 12 weeks duration partly because we couldn't convince ourselves that any kind of shorter or less robust test would really be meaningful. So as a result of that, as you mentioned, there are a few other compounds out there that are targeting NMDA modulation and cognitive impairment. But so far, the only data that we've seen from any of those is from these smaller often open-label studies.

And so it looks promising but it's difficult to say, I think, really want the degree of efficacy is. So in terms of differentiation, of course, we know more about our compounds than we do about those others. We certainly know with our compounds that the safety and tolerability profile has been very good across all of our clinical-stage compounds and all of the studies so far that we've conducted. So we would certainly hope that that would continue.

And in addition, I think the targeted effects that our drug seems to have in areas of NMDA hypofunction may enable a fairly clean focus or ability to improve cognitive symptoms without impacting anything else. So I think that's as much as we can really say because we don't know a lot about those other compounds. But we're, again, mostly focused on 458 and certainly think that the study that's in process will be a really good test of what the drug can do to improve cognition. With respect to 2925, we haven't talked specifically about discontinuation rate for 2925 in DPN.

I think what I would say is we, of course, had projected a planned discontinuation rate at the beginning of the study. And actually, we projected it before the pandemic because technically, the study kicked off right before the pandemic. And we have seen discontinuation broadly in line with that. So I think from an operational perspective, we've been pretty comfortable with how the study has proceeded. 

Unknown speaker

Thanks. That's very helpful.

Operator

Thank you, Mark. The next question comes from Joon Lee with Truist Securities. Please proceed.

Unknown speaker

Good evening. This is Les on for Joon. Thank you for taking my questions. I have two.

First, on the 783. Any notable differences in the PTSD patient screening criteria that you plan to initiate next month for the 150-mg dose that you've learned from initiating the 50-milligram dose? And then second, on the 2925 pending data in DPN and fibromyalgia, would you consider a partnership for the pivotal studies? Or are your development plans strictly internal? And is it possible that you could have DPN data as early as the AAN Meeting next month? Thank you.

Andy Kidd -- President and Chief Operating Officer

OK. Thanks, Les. So 783, I'll take the 783, and then I'll have Ashish actually answer your question on 2925 around partnerships. For 783 screening, we are trying to make sure that the two studies in PTSD are essentially the same.

So there are very minor differences. Really, the dose, obviously, is the principal one. The main design element, particularly in terms of inclusion/exclusion criteria, we want to be the same, so are as close to the same as possible. So I don't think we've learned anything yet in the 50-milligram dose that we weren't expecting to see.

I think that study has been progressing well. And so we -- certainly, we haven't made any changes to the 150-milligram protocol. And I do think for both of those studies, were we to make any tweaks or modifications, we would likely make them to both. But we haven't seen the need to do that yet.

Ashish, I'll let you answer the 2925 partnership question.

Ashish Khanna -- Chief Financial Officer and Chief Business Officer

Yeah. Thanks, Andy. I think we've been pretty clear and consistent before that we believe that if we see the therapeutic profile that we hope to show in the phase 2b, that this is a pain therapy that has a broad application and would probably best be served with the assistance of a commercial partner with larger, more well-established commercial capabilities. And certainly, I think that would be something we would explore at some point prior to commercialization.

We have a team that is well poised and prepared to take the next steps in development after phase 2b. We're already underway with those preparations. And as Andy has noted before, the phase 3, we don't anticipate would be dramatically different from what we've already done in phase 2b. We're always open to partnerships that can add value to the programs, that can advance these programs toward patients more rapidly or more responsibly and those that offer optimal value to shareholders.

So we'll engage in the wake of the data in an evaluation of whether a near-term partnership opportunity represents that high-value juncture or whether that's something down the road on the R&D path, but we're certainly open to it.

Unknown speaker

Great. Thank you for the clarification.

Operator

Thank you. The next question comes from Laura Chico with Wedbush Securities. Please proceed.

Laura Chico -- Wedbush Securities -- Analyst

Hi. Good afternoon. Thanks for taking the question. I might just ask this one a little bit differently than previously asked.

But I guess with respect to 2925, when you're thinking about portfolio allocation, I'm wondering how much of a consideration safety data might come into play when we get the DPN and FM readouts. Obviously, efficacy is going to be essential, but many chronic pain agents have REMS programs. So I'm curious if there's anything in the phase 2 readout that might be informative in terms of differentiating 2925 from a safety tolerability perspective. And then I have one follow-up for you.

Andy Kidd -- President and Chief Operating Officer

Yes. Thanks, Laura. Yes, I think you're right. They're definitely -- it is a concern in general with the current chronic pain treatments about some of the side effects and safety issues.

And there are a range of those, and they range from some things that are more serious to some things that are less serious but very common and can be quite bothersome for patients like dizziness or drowsiness and then also some issues with dependence, obviously, and abuse potential. So I think those are the main things that we'll be looking at in the data. Of course, as usual, we'll be looking to make sure that there aren't any concerns with serious or severe adverse events. We haven't had those, obviously, in our prior studies.

And so that will be an important thing to look at, but also then even in the mild and moderate adverse events, is there anything that is more common, that is a concern, we again expect and hope that, that will not be the case. I think generally, our mild and moderate adverse event profile in prior studies has been very similar to what we've seen in the placebo group. And so we would certainly hope to see a continuation of that. That would be -- or those two findings together, I think, would be a huge potential differentiator, provided, of course, that we see good efficacy as well.

But that would be really important for persistence with therapy, for the willingness of physicians to prescribe broadly and, of course, for patients to perceive that there's a risk/benefit from their point of view. On abuse potential and so forth, we do -- in this data, we do look quite carefully at any of the adverse events that are reported to determine that there's no underlying potential for abuse liability or anything like that. So that's another thing we'd be looking at as well. And again, in the past, we haven't seen anything there.

So we'd be hoping for as clean a bill of health as possible on those three areas. And if we got that, that would -- as you mentioned, it would certainly be a very important factor in this disease area. 

Laura Chico -- Wedbush Securities -- Analyst

OK. That's super helpful, Andy. Maybe the quick follow-up then would just be in a best-case scenario, you get positive readouts from FM, from DPN, while the 783 program is progressing. I guess fast-forward ahead a year or so, how do you prioritize pivotal advancement if you're successful with 2925, 783? Should we presume all the indications are proceeding? Or would there be kind of a more -- a closer assessment and allocation of resources in terms of advancing programs? Thank you.

Andy Kidd -- President and Chief Operating Officer

Thanks, Laura. Yes, I would certainly assume that we will make it happen in terms of finding between, as Ashish mentioned, external partnerships and, of course, further financing by Aptinyx that we will make it happen that the pipeline can advance. So there shouldn't be any concern about having to prioritize or reduce the number of studies that are in process or anything like that. I think quite the contrary.

I think as I mentioned in my remarks, we would view positive data in DPN and/or fibromyalgia as hugely catalytic for the company, and we would absolutely expect to move forward as quickly as we can in both of those indications and continue to keep the rest of the pipeline in PTSD and cognitive impairment moving as well. And in addition, I think we do still want to make sure it's understood by investors in the longer term. And the timing of this is probably more of a question because I think this would probably not be an immediate priority in the way that moving 2925 into phase 3 and making sure that 783 and 458 keep progressing as quickly as possible would be. But in the longer run, we do have over 1,000 other molecules in our pre-IND pipeline.

We still have, I think, a lot of potential with our mechanism that we can apply in other areas. And in the longer run, that's also something we would begin to finance. 

Laura Chico -- Wedbush Securities -- Analyst

Thanks, Andy.

Operator

Thank you, Laura. The next question comes from Myles Minter with William Blair. Please proceed.

Unknown speaker

Hi. This is Sarah on the line for Myles. Thanks for taking the questions. I've got two quick ones.

First, can you comment on if you're monitoring the blinded data in the chronic pain trials? And if so, are you seeing an improvement in pain scores from week four to week 12? And then I've got a second after that.

Andy Kidd -- President and Chief Operating Officer

Thanks, Sarah. So no, we are not scrutinizing the blinded data and trying to draw conclusions from that, so that's a fairly quick answer. I think we'll draw the conclusions when we eventually get to see the nonblinded data sets.

Unknown speaker

OK. Got it. Thanks. And then the second one was, was the powering for the secondary outcome measures in fibromyalgia study factored into the study design? Or was that study powered only for the primary endpoint? 

Andy Kidd -- President and Chief Operating Officer

Yeah. Thanks, Sarah. The powering was primarily for the primary endpoint. 

Unknown speaker

Got it. Thank you.

Operator

Thank you. The next question comes from Ram Selvaraju with H.C. Wainwright. Please proceed.

Unknown speaker

Afternoon, Andy and the team. This is Muz on for Ram. So firstly, with regard to 2925 in painful DPN and fibromyalgia, do you think return to more physical active work for some patients as the pandemic recedes has kind of a meaningful bearing on average daily pain scores, pain in walking? And is this something you're monitoring? Thanks a lot.

Andy Kidd -- President and Chief Operating Officer

Thanks, Muz. Yes, I don't know that we've heard widespread reports of that as a phenomenon that we hit in a specific way and within a specific three months' time period for each patient that is obviously in the study. The course of the pandemic from March 2020 to today has, I think, been quite different for different individuals and different types of jobs, including those that aren't working and in different parts of the country. So I think it's very difficult to kind of generalize on that.

Again, some people have been working as normal, some have not, and the time course has been very different. We haven't heard anything that's been a consistent concern about a widespread or mainstream change in activity patterns that was kind of synchronized enough to cause a concern in the clinical trial. So it's a good question, but it's not something that we have really been concerned about or that's been put on our radar as a concern. 

Unknown speaker

OK. Good to know. And then secondly, was there a reason you staggered the initiation of the two 783 trials, the two doses? Kind of concerned about the patients in the 150-milligram dose, knowing they're on a high dose versus previous patients. Or were they all blinded to this?

Andy Kidd -- President and Chief Operating Officer

So, yeah. So the process will be, at each site, that only one of the studies will be in process. So it won't be something that's a factor, we don't think, in the enrollment of the patients or anything like that. I think in terms of the staggering, it was partly to do with the fact that as you may recall, going back to kind of when we kicked off the study, we already had tested the 50-milligram dose.

We were already anticipating we would move forward with that dose, and we were able to move more quickly. We have to add, among other things, just the fairly mundane matter of actually having existing physical supplies of the drug ready to go and things like that. So we certainly felt as though it would be more efficient and quicker to start one study as quickly as possible and then the other study later. It made sense to sequence them this way because of that factor with the investigational product.

So yes, so it was partly a decision and partly actually more an upside that we were able to move more quickly with the 50-milligram dose. And so far as I mentioned, although they were staggered and although the 50-milligram -- the 150-milligram study, we think, will start screening in April, we really don't have any longer-term concerns. I think it's taken slightly longer than we had thought to get some of the sites activated, but we don't see -- we don't really have a concern at this point on the most important goal, which, of course, is to get the majority of the sites up and running, get the study enrolled and completed. 

Unknown speaker

OK. Great. Thanks for clarifying. And if I can squeeze one more in.

I was interested in Parkinson's patients. And a large percentage of them report pain. So I was wondering if you've experienced pain reporting by your PD patients in that trial and if you think any significant pain improvements are possible in PD patients with 458 given you have kind of a similar hypothesis with hypoactive regions, the prefrontal cortex being targeted with 2925. 

Andy Kidd -- President and Chief Operating Officer

Yeah, it's an interesting question, Muz. We aren't -- obviously, we're not -- I shouldn't say obviously. We're not screening for the presence of pain in the study, of course, and we don't have a specific measure for soliciting changes in pain in that study. But it will be interesting.

It's the kind of thing that there may be reports of in the study. We may get some sense as to whether that sort of overlap exists. So yes, it's an interesting area to look at. 

Unknown speaker

Fantastic. Thanks for taking my questions. Look forward to the year ahead. 

Operator

Thank you. We have no further questions at this time. I would like to turn the call back over to Andy for any closing remarks. 

Andy Kidd -- President and Chief Operating Officer

Thank you, Celia, and thank you to everybody on the line for your thoughtful questions. We appreciate your time and attention, and we wish everyone a very pleasant evening.

Operator

[Operator signoff]

Duration: 61 minutes

Call participants:

Pat Flavin -- Senior Manager, Corporate Development, and Investor Relations

Andy Kidd -- President and Chief Operating Officer

Ashish Khanna -- Chief Financial Officer and Chief Business Officer

Chris Raymond -- Piper Sandler -- Analyst

Charles Duncan -- Cantor Fitzgerald -- Analyst

Ritu Baral -- Cowen and Company -- Analyst

Gary Nachman -- BMO Capital Markets -- Analyst

Unknown speaker

Laura Chico -- Wedbush Securities -- Analyst

More APTX analysis

All earnings call transcripts