Ladies and gentlemen, thank you for standing by. Welcome to the Onconova Therapeutics fourth quarter and full year 2022 financial results and business update conference call. At this time, all participants are in a listen-only mode. Following management's prepared remarks, we will hold a question and answer session. To ask a question at that time, please press star followed by 1 on your touch tone phone. If anyone has any difficulty hearing the conference, please press star 0 for operator assistance. As a reminder, this call is being recorded today, March 16th, 2023. At this time, I would like to turn the call over to Bruce Mackle of LifeSci Advisors.
Thank you, operator, and welcome everyone to Onconova's fourth quarter and full year 2022 financial results and business update conference call. Earlier this afternoon, Onconova issued a press release reporting its financial results and business progress. If you have not seen this press release, it is available in the Investors and Media section of the company's website at onconova.com. Following my introduction, we will hear from Onconova's President and CEO, Dr. Steven Fruchtman, Chief Medical Officer, Dr. Mark Gelder, and Chief Operating Officer and Chief Financial Officer, Mark Guerin. These prepared remarks will then be followed by a question- and- answer session. Before we begin, I would like to remind everyone that made during this conference call will include forward-looking statements under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, which involve risks and uncertainties that can cause actual results to differ materially.
Forward-looking statements speak only as of the date they are made as the underlying facts and circumstances may change. Except as required by law, Onconova disclaims any obligation to update these forward-looking statements to reflect future information, events, or circumstances. For more information on forward-looking statements, please review the disclaimer in today's press release and the risk factors in the company's SEC filings. With that, I will now turn the call over to Onconova's President and CEO, Dr. Steve Fruchtman.
Thank you, Bruce. Thanks to all who have joined the call today. We are entering a very exciting time for Onconova as our recent progress has us moving toward anticipated milestones that we believe will serve as key value inflection points. I'll begin today by providing the highlights of this progress before turning the call over to Dr. Mark Gelder, our Chief Medical Officer, to elaborate further. Let me begin with a discussion of our lead asset, narazaciclib, which, as a reminder, is a multi-kinase inhibitor targeting CDK4/6 and other kinases important for tumor growth and metastasis. We are pursuing narazaciclib's development in multiple cancer indications based on both preclinical and clinical science. We are pleased to say that narazaciclib's phase 1/2a combination trial with estrogen blockade in endometrial cancer is on track to open for enrollment and screening patients later this quarter.
In parallel, our phase 1 trials of single-agent narazaciclib in the U.S. and China have continued to demonstrate the asset's favorable safety profile through their 5th dose escalation cohorts. Based on these studies, we'll be able to place patients on a once daily continuous dosing regimen in endometrial cancer as well as in future studies. Once daily continuous dosing differentiates narazaciclib from each of the 3 health authority-approved CDK4/6 inhibitors. Of these agents, which are multi-billion dollar franchises with approvals only in hormone receptor-positive, HER2- negative breast cancer, 2 of them require a 1-week drug holiday and every 4th week, mainly due to their bone marrow toxicity leading to neutropenia or a low white blood cell count, while the 3rd requires twice-daily dosing due to its shorter half-life.
By dosing narazaciclib once daily continuously, we can provide patients with a more convenient and safer dosing regimen from a marrow suppression perspective that will not include a one-week off drug holiday, during which tumor cells could potentially proliferate in the absence of kinase inhibition of their overexpressed pathways. Turning next to our investigator-sponsored rigosertib programs, our recent progress here was highlighted by phase II data reported last month in advanced squamous cell carcinoma complicating Recessive Dystrophic Epidermolysis Bullosa, or RDEB-associated squamous cell carcinoma for short. I'll let Mark detail these early data, but will note that given the results, the magnitude of the unmet need in RDEB-associated squamous cell, and its ultra-orphan nature, we plan to seek guidance from the FDA on the most expeditious path towards a potential approval for rigosertib in this indication.
In addition to highlighting these clinical accomplishments, Mark will preview upcoming posters on narazaciclib, our lead compound, that will be presented at the AACR meeting in Orlando next month. He will also recap preclinical data on rigosertib that were presented at the recent AACR Targeting RAS Conference last week. Before I hand the call off to Mark, I'd like to highlight the important and recent appointments of Doctors Peter Atadja and Trafford Clarke to our Board of Directors. Together, Peter and Trafford bring more than 50 years of experience in the pharmaceutical industry to our board, having had key positions with increasing responsibilities at both Novartis and Eli Lilly, respectively. In the short time since their appointments, they've already provided invaluable insights informed by their extensive knowledge of drug development leading to commercialization.
Looking forward, I am eager to continue benefiting from their wise counsel as we pursue our mission of discovering, developing, and delivering best-in-class products to patients with cancer. With that, I'll now turn the call over to Dr. Mark Gelder to provide more details and context on our recent clinical and scientific accomplishments. Mark?
Thanks, Steve. I'll start with a quick update on narazaciclib's phase I solid tumor program. I'm going to focus on the program's U.S. study, referred to as Study 1901. This study is evaluating the continuous once-daily dosing regimen that we plan to utilize with narazaciclib moving forward. The trial recently completed the 5th dose cohort. This was a cohort of patients who took 200 mg a day by mouth on a continuous daily basis, days 1 through 28, each cycle being 28 days. We expect it will advance to the 6th dose escalation cohort, which will evaluate the safety, tolerability, PK, and PD of a 240 mg dose of narazaciclib orally once daily. We expect to move to the 6th dose escalation cohort after the safety monitoring committee has reviewed the data from the 5th dose cohort.
Data from the trial continues to be highly encouraging, with anticipated on-target effects of narazaciclib observed, but in the absence of any clinically meaningful cases of neutropenia or diarrhea. This is important since, as Steve pointed out, neutropenia is the dose-limiting toxicity for two out of the three approved CDK4/6 inhibitors, while diarrhea is the primary dose-limiting toxicity for the third one, abemaciclib. These early clinical findings are also notably consistent with narazaciclib's differentiated kinase inhibitory profile as well as its preclinical data that showed reduced neutropenia when directly compared to the most widely prescribed CDK4/6 inhibitor, palbociclib.
On our last earnings call, you heard Steve and I speak about how narazaciclib's differentiated inhibitory profile positions it as a potentially best-in-class therapy when combined with letrozole in patients with recurrent or metastatic Low-Grade Endometrioid Endometrial Cancer, or LGEEC. We also announced that we plan to begin exploring this hypothesis in a phase I, 2a trial, which has received IRB approval at New York University Langone Health. We expect the study to be open for enrollment later this quarter as planned, and are very pleased that it remains on track for a preliminary data readout in the fourth quarter of this year. Several other sites are on track to be open and up and running in the coming weeks.
As a reminder, the scientific rationale for the narazaciclib LGEEC study comes from a randomized, placebo-controlled phase II study as well as a couple of different single arm clinical trials of the currently available CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib in patients with estrogen receptor-positive endometrial cancer. These trials all demonstrated the improved anticancer activity of CDK4/6 inhibitors when combined with letrozole when compared with letrozole plus placebo in the Low-Grade Endometrioid Endometrial Carcinoma patients. It was these trials that support the compendia listing of the three currently available CDK4/6 inhibitors that enable their off-label use and reimbursement in this setting today. I think it's important to realize that none of the currently available CDK4/6 inhibitors are FDA-approved for the treatment of Low-Grade Endometrioid Endometrial Carcinoma, and they are limited by the shortcomings related to safety, tolerability, and treatment resistance, as we've discussed before.
Given narazaciclib's ability to inhibit CDK4/6 with similar potency to palbociclib, ribociclib, and abemaciclib, we believe our phase 1/2 trial has a high likelihood of technical and regulatory success. Moreover, we believe our preclinical and phase 1 findings suggest that narazaciclib may offer significant safety advantages compared to currently available agents. Its ability to target additional proteins related to antitumor immunity, metastases, cancer cell survival, et cetera, may lead to improved efficacy. We therefore believe that narazaciclib has the potential to substantially improve the treatment paradigm for patients with recurrent low-grade endometrioid endometrial cancer and look forward to evaluating this hypothesis in our phase 1/2A trial. Looking beyond low-grade endometrioid endometrial cancer, we are planning to initiate a clinical program of narazaciclib in one or more additional indications by the end of this year.
While we can't provide too much detail on these plans since they are still being finalized, I can say that other refractory tumors of the female reproductive tract, as well as breast cancer, are under consideration. Protocols for these clinical trials are currently being prepared for review, and we have identified key opinion leaders to serve as the principal investigators of the additional studies being planned. To conclude my section on narazaciclib, I want to briefly preview two posters on preclinical data that will be presented at the upcoming American Association for Cancer Research, or AACR meeting next month in Orlando. The first of these posters will feature results that demonstrate narazaciclib's single-agent activity against mantle cell lymphoma in vitro and in a chicken embryo chorioallantoic membrane xenograft model.
Importantly, narazaciclib's activity against mantle cell lymphoma cell lines was found to be superior to that of palbociclib and ribociclib and similar to that of abemaciclib. When narazaciclib was combined with ibrutinib, a BTK inhibitor approved for the treatment of mantle cell lymphoma, synergistic increases in antitumor activity against both BTK inhibitor-resistant and BTK inhibitor-sensitive cell lines were observed. The second poster that we will be presenting at AACR next month will compare the differential cellular targets that are engaged by narazaciclib compared to the FDA-approved CDK4/6 inhibitors. Results from a cell-based mammary cell carcinoma model show that stronger induction of apoptosis with narazaciclib was observed compared to palbociclib.
As will data that will show narazaciclib combining with autophagy inhibitors to sensitize breast cancer cells to cell death. While the conference embargo policy prevents me from saying much more about the data featured in these two posters at this time, we look forward to having further discussions with the scientific and clinical community at the AACR meeting next month. Shifting gears, I'll now discuss our investigator-sponsored rigosertib programs with a focus on the exciting early clinical data in the RDEB-associated squamous cell carcinoma, which was reported back in February. As those familiar with Onconova may recall, RDEB is caused by insufficient type VII collagen protein expression. This deficiency in type VII collagen leads to extreme skin fragility, chronic blistering, and wound formation in these RDEB patients, many of whom go on to develop squamous cell carcinomas, frequently metastatic, that are driven by overexpression of PLK1.
Unfortunately, all of the currently available treatments, including targeted therapy, immunotherapy, conventional chemotherapy, radiation therapy, et cetera, provide only limited benefit for RDEB-associated squamous cell carcinoma patients who have a cumulative risk of death of 70% by age 45. To address the unmet needs of patients with RDEB-associated squamous cell carcinoma, we are working with multiple investigators on a phase II program evaluating the safety and efficacy of rigosertib monotherapy in this patient population. Last month, we announced that the trial's second evaluable participant achieved a complete clinical response of all cancerous skin lesions after only 4 cycles of therapy. This patient remains on study with additional scans scheduled to monitor metastatic disease.
The announcement of this 2nd patient followed data that showed a complete clinical response in the program's 1st evaluable participant, who has remained in complete remission with no signs of metastatic disease for more than 24 months while remaining on rigosertib. The studies remain open and are continuing to enroll patients. We are actively looking for additional sites to participate in the program. While data from an N of 2 must always be taken with caution, the results from rigosertib's RDEB-associated squamous cell carcinoma program have far exceeded our expectations as well as those of the trial's investigators. They have confirmed rigosertib's activity against PLK1 in the clinic, as well as its ability to drive durable clinical responses in patients who have failed prior therapy.
As Steve mentioned, the next step for the program is now to engage with the FDA to align on the optimal regulatory path for the program given our data to date and the lack of effective treatments that are currently available for patients with RDEB-associated squamous cell carcinoma. In addition, RDEB is a catastrophic pediatric illness, and this reality, as well as the potential enrollment of pediatric patients in the clinical program, will be some of the topics to be discussed with the FDA. Taking a broader view, we believe the results from rigosertib's RDEB-associated squamous cell carcinoma program may have positive read-through into other more prevalent cancers characterized by PLK1 overexpression.
This is a hypothesis being explored in preclinical studies, though I should note that any effort to advance rigosertib's clinical development in additional indications would be enabled by investigator-sponsored trials so that we can continue to dedicate our primary focus and resources on narazaciclib. Lastly, I'd like to touch on the status of the two investigator-sponsored trials evaluating rigosertib in combination with a PD-1 checkpoint inhibitor. These trials are supported by preclinical data published by Dr. Ann Richmond's group at Vanderbilt University, as well as results recently presented at the AACR Targeting RAS conference recently held in Philadelphia, Pennsylvania. This data showed how rigosertib can stimulate an anticancer immune response via activation of the NLRP3 inflammasome. Collectively, these preclinical data provide a strong mechanistic rationale for the aforementioned trials, which aim to leverage rigosertib's immunotherapeutic effects to overcome checkpoint inhibitor resistance.
The first of these trials I'll mention is designed to evaluate rigosertib plus pembrolizumab in checkpoint inhibitor refractory metastatic melanoma. I am pleased to say that this trial has recently been posted on ClinicalTrials.gov, now has an NCT05764395, and should be open for patient accrual at Vanderbilt University Medical Center later this quarter. We look forward to providing additional updates as this trial progresses. The second rigosertib checkpoint inhibitor combination study I'll mention is the phase 1/2a trial evaluating rigosertib plus nivolumab in KRAS-mutated non-small cell lung cancer patients who have failed prior therapy with a checkpoint inhibitor. We remain on track to report additional data from this trial in the first half of this year.
This announcement will likely include updated data from the two patients who remained on study as of its readout at ESMO last year, as well as data from additional patients who were not yet enrolled and or evaluable for efficacy as of the ESMO data cutoff date. After seeing these data, we plan to discuss them with the study investigator to determine the optimal next steps for this program. Now with that, I'll pass the call off to Mark Guerin.
Thank you, Mark. Onconova finished 2022 in a strong financial position with cash and cash equivalents of $38.8 million as of the end of the year. This compares with cash and equivalents of $55.1 million at the end of 2021. Based on our current projections, we believe our current cash position will be sufficient to fund our ongoing clinical trials and operations into the first quarter of 2024. This cash runway is expected to take us through key milestones, including a first data readout from our combination trial of narazaciclib and letrozole in advanced endometrial cancer later in 2023. Turning now to our full year financial results, research and development expenses for 2022 were $11.4 million, compared to $7.3 million for 2021.
General and administrative expenses for 2022 were $8.4 million, compared to $9.4 million for 2021. Our net loss for 2022 was $19 million or $0.91 per share on 20.9 million weighted average shares outstanding. This compares with the net loss for 2021 of $16.2 million, or $0.96 per share on 16.8 million weighted shares outstanding. The increase in net loss for 2022 compared with 2021 was primarily a result of higher spending in the narazaciclib development program and drug manufacturing in 2022. That completes my financial review. I'll now pass the call back to Steve.
Thanks to both of you Marks. I'll start my closing remarks by thanking all of those who made the progress we spoke about today possible. At the top of this list are our clinical trial participants and their caregivers, whose bravery is a constant source of inspiration to all of us. I'd like to also thank our employees, investigators, partners and shareholders for their support, which has us advancing towards multiple key milestones that you heard about today that are expected between now and the year-end. In our narazaciclib program, we expect to report preliminary data from our combination trial of narazaciclib and letrozole in advanced endometrial cancer in the fourth quarter of this year.
We also expect the continued progress of our phase I trials to enable the selection of a recommended phase II dose in the first half of the year, and to initiate a clinical program of narazaciclib in one or more additional cancer indications. Regarding rigosertib, we look forward to discussing our recent RDEB associated squamous cell carcinoma data with the FDA in order to help determine the optimal regulatory pathway for these exciting clinical outcomes. We also look forward to opening the combination trial of rigosertib and pembrolizumab in melanoma later this quarter, and expect that the phase 1/ 2a trial of rigosertib plus nivolumab in KRAS-mutated non-small cell lung cancer will have additional important data to report in quarter 2.
In parallel with the progress of our clinical programs, we will continue to evaluate potential opportunities to expand our pipeline. We'll focus any such efforts on assets that have a strong body of evidence demonstrating their best-in-class potential in an indication with a high unmet medical need. We plan to be very highly selective as we make these corporate development assessments, as our current programs are backed by compelling data and provide us with multiple shots on goals and opportunities to generate value for our investors and the patients. With that, we'll begin today's Q&A session. Operator.
Ladies and gentlemen, if you wish to register for a question for today's question- and- answer session, you'll need to press star then the number one on your telephone. If your question has been answered or you wish to withdraw your request, you may do so by pressing star one again. If you're using a speakerphone, please pick up your handset before entering your request. One moment please for the first question. Our first question comes from Charles Zhu from Guggenheim Securities. Please go ahead, your line is open.
Hi guys, this is Edward on for Charles Zhu at Guggenheim. My first question is on narazaciclib, the monotherapy dose escalation. I'm curious if you can give any more color on how the dose escalation is going beyond the prepared remarks. Do you think you're in the potentially therapeutic, a therapeutically efficacious range for the doses and how much higher do you think you could go? As a follow-up, I know you've guided to the letrozole combo data in 4Q, how should we be thinking about the monotherapy dose escalation data update? Could that come before the 4Q update?
Thanks, Ed. I'll ask Dr. Gelder to take that, please.
Sure. More clarity on the phase I dose escalation study. What I can tell you is that we do believe that we're getting close to a quote-unquote dose that we can use as our recommended phase II dose. We are beginning to see some effects that we would anticipate from a CDK4/6. i.e., we're beginning to see a little more grade 1, grade 2 neutropenia. We're not seeing a whole lot other than that. We're seeing some low-grade diarrhea, but nothing significant. The PD work, the pharmacodynamic work with the 200 mg cohort is still pending. It's still out, so I can't say anything for certain about that. Just based on what I'm seeing, do I think that we're getting relatively close? Yeah, I do.
Does that mean 240 mg is gonna be the dose, 280 mg, you know, 320 mg? I don't know. Do I think we're gonna have to push this to 500 or 600 mg? No, I do not. I do think we're getting closer, but I can't give you a firm answer to that. Yeah.
Mark, the second question was the strategy of the monotherapy trial when we also we've already begun the combo trial with letrozole. Make some comments on that?
You know, we're looking at different options right now. You know, whether we do continued work with, in combination with either letrozole or other anti-estrogens, whether we do work, as a monotherapy, whether we do some continued work with narazaciclib in combination with, say, a checkpoint inhibitor or in combination with, you know, a BTK inhibitor or in combination with a MEK inhibitor. We're looking at several different options now. I can't give you any more specific details at this time. What I will tell you is that we believe we do have several good options in terms of additional development programs to start moving forward with other than the low-grade endometrioid endometrial cancer.
Exactly what our second program and third program and fourth program will look like at this time, I just can't say. Steve, you may wanna give a little more away, but I'll hold my comments there.
Sure. No, I think Ed's question, and correct me if I'm wrong, Ed, is How do we start a combination trial with narazaciclib before we know the recommended phase two monotherapy dose? I think the answer-
Oh.
Ed, the answer is that as Dr. Gelder said, we believe we're close to the recommended phase II dose. Anytime you do a phase I new combination, you always decrease the dose of the experimental agent, in this case, narazaciclib. Since we think we're close, we know, we went back 1 step, 1 cohort, picked that dose of narazaciclib in combination with letrozole, and in a 3-by-3 design, we'll again continue to increase the dose of narazaciclib in combination with letrozole based on the safety profile that Dr. Gelder will be observing. I hope that answers your question.
That's great. Thank you.
Thank you.
Our next question comes from Ahu Demir from Ladenburg Thalmann. Please go ahead. Your line is open.
Good evening. Hello, team. Thanks for taking my questions, and congrats on the progress. I have two questions. One of them, we heard you say the entity was not reached, and also you don't observe the neutropenia and diarrhea. I am curious to hear if you could provide more color on the similarities or differences between narazaciclib with other CDK4/6 inhibitors. Do you observe similar safety profile, or is it very differentiating? If you could provide some color on that would be helpful.
Mark?
Yeah. I think, when I look at what really differentiates us, you know, as you're well aware, palbo and ribo are the two, quote-unquote, "purest" CDK4/6 inhibitors, with ribo being the purest, followed closely by palbo. Abemaciclib, like narazaciclib, is truly a multi-targeted kinase inhibitor. It hits several different kinases at low nanomolar concentration. The kinases that abemaciclib hits are very different than the kinases that narazaciclib hits. All of them are very potent, very effective CDK4/6 inhibitors. What differentiates narazaciclib are the other kinases that it hits at low nanomolar concentration, particularly the ARK5 or NUAK1 and the CSF1R. There are others. The FLT3, the C-KIT, et cetera.
There are actually several kinases that we hit that we think have the potential to be very important in terms of the overall efficacy as well as the safety of narazaciclib. This is all preclinical data. We're just getting into the clinic. We've now had in our phase 1 dose escalation study, we've now had 21 patients total who have been exposed to the narazaciclib at escalating doses. As I said, so far, the safety profile looks very, very good, very similar to what we had anticipated based on all of our preclinical data.
We are very excited, as we've said, to be moving into the low-grade endometrioid endometrial cancer study, because now rather than using a typical phase I solid tumor population, we will be using a population where we expect, where we anticipate to start to see some really significant activity. This is sort of where we are. I hope that answers your question, but it all has to do with the other kinases that we inhibit.
Actually, there'll be more data that Mark alluded to. There'll be greater detail at the AACR meeting in Orlando.
That's helpful. Thank you. I have one more question on the letrozole combination trial. Since both drugs are administered daily, I am curious if you have looked at the safety profiles. Are there any overlapping toxicities? Are you expecting anything major in the combination trial?
When I look at letrozole and it's got a very well-established AE profile. When I look at what we've seen so far with narazaciclib and what we expected based on the other CDK4/6 inhibitors that are already approved and based on our preclinical data, there really is very little overlapping toxicities of the two. The biggest one is really fatigue.
If I can add to that and also add to the previous question, because letrozole is an antiestrogen and as Mark just said, a very different safety profile and a very acceptable safety profile, a very different mechanism of action as an antiestrogen. Rather than waiting to wait for the recommended phase 2 dose of mono narazaciclib study to read out, we are comfortable combining narazaciclib with letrozole with a lower dose of narazaciclib to, you know, make sure we're safe. This approach of already opening the combination trial and in endometrial saves us two key factors, which are both very important, time and money. We now will have, as we mentioned, in this quarter, the first patient on this combination trial with endometrial cancer, studying the combination.
Thank you. Thanks for taking my question.
Our next question comes from Joe Pantginis from H.C. Wainwright. Please go ahead. Your line is open.
Hey, guys. Good afternoon. Thanks for taking the question. This might be jumping the gun a bit here. Obviously you need to talk to the FDA first with regard to rigosertib's potential in RDEB. With that said, do you have, I guess, any sort of broad strokes to take right now, both internally and maybe from any external sort of regulatory consultants that, you know, might give you an early wish list that you can share with us regarding a potential design?
The wish list, Joe, won't require a design. The results that Dr. Gelder shared with us, the patients and the experts who see these patients are extraordinary. They have failed everything else, and as we mentioned, we have complete cutaneous responses. This is an ultra-rare disease, and we have already demonstrated complete responses when nothing else works. Our regulatory consultants are the ones saying we should go to the FDA now and ask the question, what will it take to get rigosertib approved in squamous cell complicating RDEB? We don't know if the current two patients are enough. Will they want an additional two patients? We really don't know what the end is going to be. As Mark said, hopefully before we meet with the FDA, maybe we'll have one or two additional patients.
The incidence of this disease in the U.S. is 100 odd, about 100 RDEB patients a year. Maybe 50 live long enough to develop squamous cell carcinoma, but it's very hard to identify these patients, as you know. In addition, the other wish is because this is a pediatric disease, the RDEB expresses itself in the pediatric age population. We are told that periodically, a child is seen with squamous cell, mostly the young adults who develop the squamous cells. The two patients that we treated are in fact young adults. This will be presented in greater detail at the International Societies for Investigative Dermatology (ISID) Meeting in Tokyo, Japan, that's coming up. We are continuing to look for additional patients and if we're very lucky, but it may not be necessary to find a pediatric...
It is hard to say lucky to find a cancer in a child, but if there is a child out there anywhere in the globe that we become aware of, we of course would be very interested in treating that child with rigosertib, and discussing the possibility of a pediatric voucher for squamous cell complicating RDEB. Those are our wish lists, to get rigosertib approved in this indication and to discuss the possibility of a pediatric voucher with the FDA.
Very helpful, Steve. Thanks a lot.
Our next question comes from Robert LeBoyer from Noble Capital Markets. Please go ahead. Your line is open.
Good afternoon. I had a question that I think was partially answered earlier. If you're going into a sixth cohort for narazaciclib, could you give any kinda time frames as to when the sixth might be completed or the seventh or even an eighth, if you go that far, and when you might start the phase II?
Mark?
It's impossible to say when a cohort is going to get completed. You know, you have a 3 plus 3 design, and it depends on if you get a DLT, it depends on how many screen failures you have, et cetera, et cetera. You know, typically it takes, if you don't have any significant problems, don't have a lot of screen failures, et cetera, you can complete a cohort of 3 in, you know, 2- 3 months. If you have a DLT and then have to expand it out to 6, or if you start having several screen failures, et cetera, it can take, you know, 4, 5, 6 months to complete a single cohort. It's really impossible to say.
Our 5th cohort, as you're all well aware, took several months to complete because we had several screen failures, et cetera. That's just the nature of clinical research. The first 4 cohorts, we all completed. We completed each one of them in 2 to 3 months. In terms of how many cohorts we're gonna have to go, I do not have a crystal ball. I can't tell you. Do I, in my gut, do I think we're probably getting close? Yeah, I do. The 6th cohort is at 240 mg. Will that be as high as we need to go, or do we need to go to 280? That decision won't just be driven by the AE profile.
It will also be driven by the PD data, the pharmacodynamic data, because we're gonna look for a dose that maybe isn't the MTD or maximal tolerated dose, but look for a dose where we see, you know, maximal biological effectiveness too. It's just hard to say.
Okay. Thank you very much.
Thank you.
I'm showing no further questions in queue. At this time, I'd like to turn the call back over to the speakers for closing remarks.
Thank you all again for joining today to hear about our recent progress and outlook for the rest of the year. We're obviously excited to be nearing several important clinical milestones and appreciate your continued interest in the important, if not crucial, work we are doing. Thanks again, enjoy your evening and look forward to seeing many of you going forward. Thank you.
Ladies and gentlemen, thank you for your participation on today's conference call. This concludes today's event. You may now disconnect.