Atossa Therapeutics at Jefferies Conference: Strategic Moves in Breast Cancer

On Thursday, 05 June 2025, Atossa Therapeutics (NASDAQ:ATOS) presented its strategic initiatives at the Jefferies Global Healthcare Conference 2025. The company is targeting a significant opportunity in estrogen receptor-positive breast cancer with its lead molecule, Z endoxifen. While Atossa is progressing towards FDA approval, it also faces challenges in patient adherence due to treatment side effects.

Key Takeaways

• Atossa aims to capitalize on the multi-billion dollar market for estrogen receptor-positive breast cancer with Z endoxifen.
• The company is financially robust, with a cash runway of over two years and no debt.
• Atossa is pursuing FDA approval by focusing on the metastatic setting as the quickest path.
• Generative AI is being used to find effective drug combinations, showing promise with CDK4/6 inhibitors.
• The company plans to enroll the first patient in its FDA-approved trial by the end of the year.

Financial Results

• Cash Position: $65 million as of March 31
• Market Cap: Approximately $112 million
• Debt: No debt on the balance sheet
• Cash Runway: Over two years with current operations

Operational Updates

• Submitted a briefing package to the FDA for Z endoxifen.
• Collaborating with Lilly in the I Spy trial to explore Z endoxifen with CDK4/6 inhibitors.
• Conducting generative AI work with In Silicone Medicine to identify synergistic drug combinations.
• Planning to begin patient recruitment for an international trial by the end of the year.

Future Outlook

• Focus on obtaining FDA approval in the metastatic setting first.
• Exploring additional applications in neoadjuvant, adjuvant, and prevention settings.
• Continuing to use AI to identify new drug combinations.
• Reporting on clinical trial progress throughout the year.

Q&A Highlights

• Dr. Quay emphasized Z endoxifen’s superior safety and efficacy compared to Tamoxifen and other treatments.
• The company is optimistic about Z endoxifen’s ability to induce apoptosis in cancer cells, potentially improving patient outcomes.
• Atossa aims to have the first patient in the FDA-approved registration trial by year-end.

For a complete understanding of Atossa’s presentation and strategic plans, please refer to the full transcript below.

Full transcript - Jefferies Global Healthcare Conference 2025:

Mayor Leitman, Jefferies Healthcare Investment Banking, Jefferies: Good morning, everyone. My name is Mayor Leitman from the Jefferies Healthcare Investment Banking team. And it is my, true honor and pleasure I met a little bit of the Atosa team a couple minutes ago, but my true honor and pleasure to, to introduce Doctor. Quay here, Chairman and CEO of Atosa. Atosa’s focus specifically on the breast cancer and the oncology sector, and we’ll learn a little bit about it during the presentation.

Doctor Quay, Chairman and CEO, Atosa Therapeutics: Thank you and good morning everyone. Welcome to the Atosa Therapeutics corporate presentation. Whoops, let me back up. We are a public company on NASDAQ under the symbol ATOS and so you should review all of our SEC filings before making any investment decisions. I will be making forward looking statements today.

Atulsa is addressing a multi billion dollar opportunity in estrogen receptor positive breast cancer. This is with our lead molecule Z endoxifen which has many unique properties which I’ll go through today. It’s demonstrated broad utility from the earliest stage which we consider the prevention of breast cancer through the early diagnostic phase called neoadjuvant to then the stable adjuvant treatment and now with our focus with FDA approval in the metastatic space. You can see that it covers the metzen bounds of the entire space. We have a robust and growing IP portfolio.

I’ve invented seven drugs that are FDA approved. I have 92 patents. So I’m very proud of the patent estate we’ve built at Atosa because it’ll add great value for shareholders in the future. We also have a very experienced leadership team. Some of them are here today with us.

And finally, have a strong financial position. We are one of probably only 20% of biotech companies in the space that have over two years of cash and are trading well above our cash position. So this is the leadership team here. In the room with me today is our CFO, Heather Reese, as well as Michael Parks, our VP of investor and public relations. We also have two experienced executives.

One who’s just returning from the ASCO meeting in Chicago, Doctor Claudia Lopez and Dele Behan, our VP of operations. As I indicated, we are guided by a world class leadership advisory group that includes Doctor. Per Hall on the left from the Karolinsky Institute where he has been deeply involved in breast cancer prevention and we’ve been supporting and working with him for many years. In addition, Laura Esserman who is a professor at the University of California San Francisco, literally the architect of the iSPY adaptive clinical trial process is doing some very exciting work for us with zeandoxifen which I’ll get into. Doctor Matthew Getz, an MD from the Mayo Clinic who’s probably has the most clinical experience with zeandoxifen and is our principal investigator for the Evangeline trial.

And finally Doctor. David Leiden here in New York City who is deep in the research in our triple negative breast cancer programs. So the problem is that there is unmet needs in estrogen receptor positive breast cancer. About forty to fifty percent of patients stop taking the treatment at some point during its timeframe. And this is principally driven by the adverse events.

Many of the drugs have minor but significant frequency adverse events that lead women to simply stop taking the drug. And of course, there’s no benefit when a woman is not taking her drug. And that’s one of the things we focus on is crafting a profile for zeandoxifen that is tolerated and very well attractive in that perspective. There’s another population of patients, almost half of the patients who don’t respond to first line aromatase inhibitors plus CDK four six inhibitors. This is a class of drugs that is commonly used but again almost half of the patients don’t have a proper response to it.

And finally, the gold standard if you could call it before zeandoxifen came along, the fulvestrant monotherapy also has a high level of failure in the settings here. So despite all of the endocrine therapy that’s been around for a very long time and which is addressing the most common kind of breast cancer, there are significant unmet needs that we believe zeandoxin will address. These include improved efficacy, reduced resistance, induced apoptosis. This is an important kind of scientific y thing but nonetheless, most endocrine therapies are static. That is they stop the cell from growing, they put the brakes on it, but when you stop taking it the brake comes off and the cancer continues.

Z endoxifen is quite unique in having a pathway that again I’ll go into the science a little bit more a little bit later. But a pathway which actually triggers what’s called apoptosis. Our cells are programmed to commit suicide effectively to kill themselves and at certain levels in certain kinds of cancers, zeandoxin triggers that. And that is quite unique. Finally, improved adherence.

Again, this gets down to those frequent, not necessarily medically important but for the patient very important side effects that if you can get around, if you don’t have them with your drug, the adherence, which is the definition of people taking the medicine long term according to prescription their doctor has given them improves greatly. And again, you don’t get any benefit if someone’s not taking your drug. So a little bit of chemistry. I will not have a test after this although I love chemistry. Tamoxifen, which is the mainstay of breast cancer treatment, probably the most commonly administered drug in the history of cancer treatment if you go back to the fifties even, is not a cancer drug itself.

It’s what’s called a pro drug. Which means there’s two kinds of chemistries that have to happen in the liver before it becomes active. The first chemistry is to put hydroxyl group on the phenyl ring. So can I point with this or I guess I can? Yeah, maybe I can here.

I’ll skip that. In any case, the top middle called four hydroxytomoxane is the product of putting hydroxyl group on the phenyl group. And then the drop down from that where you see Z and dioxin is in fact the active ingredient of tamoxifen and it involves taking a methyl group off of that amine. So it becomes a primary amine as opposed to a secondary amine. So all of this metabolism of tamoxifen is required for it to have any effect at all on breast cancer.

And it also makes other things. It makes about 21 different chemicals. Many of which have pharmacological activity that we don’t necessarily want. So tamoxifen is, you talk about it as being a dirty bomb as opposed to a laser guided missile. It’s kind of the way to think about it.

You can give a drug that gives 21 different chemicals or you can give the only one that has activity. And there it is. Just to be sure you can find it in the chart there. Zeandoxifen is the drug that we have. The one that we have our patent portfolio on that we’re very excited about.

So let’s talk about its differentiation in the space of ER positive breast cancer. First and foremost, it has superior estrogen receptor antagonism. So breast cancer, seventy five percent of breast cancers are driven by the estrogen receptor which is a protein in the cytoplasm. Estrogen will bind to it under normal circumstances. It goes to the nucleus and within about fifteen minutes it changes 5,000 different protein manufacturing processes in a process that drives normal estrogen activity in women but also when it’s hijacked drives breast cancer.

So in order to stop that, you need to get between the estrogen that the woman has in her cell and the receptor itself. Zeandoxin does that better than any other drug. It’s that simple. So that’s his first step of differentiation which is really, really important. The second step is what I talked about earlier which is programmed cell death or apoptosis.

Doctor. Getz was really the primary finder of the fact that Zeandoxin unlike any other estrogen therapy that we are aware of is a PKC beta one inhibitor. So we don’t have to say that again, it’s complicated. But nonetheless, what it means is that zeandoxin alone in a ER positive breast cancer has the potential to cause the cells to commit suicide effectively killing the cells. One of the challenges with estrogen receptor positive breast cancer is like the challenges we had with COVID if you think about it.

Where you have a vaccine and then the virus escaped the vaccine. Breast cancers can do the same thing. And when you put pressure on them with estrogen receptor inhibitors, forty to fifty percent over six months to two to three years will develop a mutation in the estrogen receptor which make those drugs no longer effective. They just simply can’t bind anymore. Zeandoxifen in that setting continues to have activity.

And so we’re very excited about this potential because as I’ve indicated, almost all metastatic patients will have one form of estrogen receptor mutation or another. And we have activity in that. At this point in time, after testing hundreds and hundreds of women, we have an improved safety and tolerability profile compared to, for example, tamoxifen which has about eighty percent adverse events of the type of vasomotor or night sweats and flushing and that sort of thing. Or aromatase inhibitors where about forty percent have an arthritis that’s limiting and causes them to go off the drug. So in both of those particular comparisons, Zeandoxifen is very very clean with respect to its adverse events and that’s very attractive.

In the last year and a half, we’ve done a great deal of generative artificial intelligence work with a company up in Boston called In Silicone Medicine. The purpose of this was to basically computational avatars of breast cancer of female physiology and then to look at what drugs have activity in breast cancer in addition to zeandoxin and where are they synergistic? Where is one plus one, three or four? And so this work has been very gratifying and it’s wonderful to report that for example, Zeandoxin appears to be the best coupling with a CDK foursix inhibitor. And right now in the I Spy trial in San Francisco, Lilly has contributed their drug to our trial, we’ve contributed ours and we’re very excited to look at the potential of these two drugs working together.

And there other combination opportunities for zeandoxifen that we are exploring. So I indicated indoximin covers the met’s and bounds of breast cancer and what I meant by that was if you think of the breast cancer process, zeandoxin has a role at every one of the points. So let’s talk about prevention. There is a group of women who are at very high risk of breast cancer. They can be identified in a number of ways.

One of the simplest ways is the high density that they have on their mammogram and some additional parameters that are found in the mammogram that are identified by software programs and the like. But for example, twenty percent of women who have a particular pattern of high density and other features will have a very high incidence of what’s called an interval cancer. A cancer before the next interval, the next two year mammogram. And so one of the interesting ideas that we have would be to address that population. Screening women for mammograms for cancer, identifying those that are high risk of a cancer in the next two years and then studying that to show that we had superior activity, we actually could prevent those interval breast cancers.

So that would be an approach to prevention if we were to go into it. As you know, we have focused on metastatic. But I think one of the things you should understand is that we believe the metastatic landscape is a foundation for atosa to then move into the other perhaps larger markets, more impactful markets. Let’s go from prevention to women who have been newly diagnosed and they have a four to six month period of time when you can begin to treat the tumor before you do the definitive surgery. Maybe they need radiation.

That’s called the neoadjuvant phase. And the way to measure those, they’re very attractive trials for identifying the efficacy of a drug because within thirty days you can look at something like KI 67 to see that the cells have stopped growing. Within three to four months, you can begin to look at MRIs to see that the tumors are shrinking and between four and six months you can do the surgery where the pathologist takes it out and looks at it and says, you know, there’s a lot of dead cancer here. I can’t find any living cancer cells. So we have studies that are looking at each of those three time points with our drugs.

We begin to report them last year in December. We will continue to report ongoing trials in that space, that neoadjuvant space and they’re very informative and very predictive of what will happen in longer term trials. You know, that’s frankly why you do these kinds of science y studies. The adjuvant setting is what happens after the woman’s definitive treatment has been done and you have two goals. Preventing local cancer in the breast if they conserve the breast.

You wanna prevent a recurrence in that breast which is at a higher instance once you’ve had cancer. And unfortunately, women have a higher incidence in the contralateral breast. And so those are the two targets for the adjuvant treatment. And again, one of the key features for Zeandoxin in this space will be its side effect profile. Because it’s up against drugs that have eighty percent side effects with respect to tamoxifen, forty percent arthritis side effects with respect to AI inhibitors which are the mainstay of this particular space.

So we believe that at an appropriate time, we can come into the adjuvant market with a very attractive safety profile and that 50% adherence should go much higher with our drugs. Finally, we spent the first quarter taking the data we generated during 2025, looking at it, packaging it for KOLs, key opinion leaders around the world, international group to say with this scientific protocol and then bringing regulatory authorities, people from ex FDA people who are now in industry and giving the two of them the charter to say, with this package of drug, with this profile, and with your knowledge of FDA approval process and the like, where do you see the fastest opportunity for Atosa Therapeutics to get a drug on the market? And the end of that process was something we announced in March, which was the metastatic route. The next step from that is to then, okay, it’s great your KOLs like it, it’s great that your regulatory folks say this is gonna fly well. But the truth is of course what happens when you go to the FDA.

We took their work and our work and put together what’s called a briefing package. You go to the FDA, you send it to the FDA, they make comments about it, you have a meeting, they generate minutes and so that’s the process we’re in over the next three to four months and we’re very excited to see what they have to say about it. We think we have a very strong position there. And so metastatic will be the target for a ptosis first approval. But I want to also set the stage that if you back up to adjuvant, a neoadjuvant in prevention, this drug has very broad and deep legs in this entire space.

So as I’ve indicated, we are now focused on metastatic setting. The pharmacodynamic effects there are very, very powerful and there have been studies already in this setting that have been done by other people, National Cancer Institute, the Mayo Clinic, which again will de risk this path for Atosa Therapeutics and de risk it for our shareholders as well. So this is some preclinical data that we have. These are on our website. But you can see in the left hand panel where you look at an ER positive breast cancer model in the laboratory.

The black circles are the growth of the tumor over time. It grows very quickly obviously in this mouse model. And then the red and blue are what the impact of zeandoxin on that where you actually see not only does the tumor stop growing, it actually gets smaller. Much like we’ve seen with our patients. Another different tumor, different ER positive breast cancer tumor in the right panel shows the same effect.

And you can see that against fulvestrant, there’s not a statistically significant difference. This does translate into the clinic. So if you look at those two MRI images, one before treatment and one after treatment, you can see a significant reduction in tumor size. And again, in a trial up against tamoxifen for progression free survival, which is the clinician’s observation of the patient. You can see a very statistically significant and clinically significant increase in survival for women with Indoxifen versus Tamoxifen.

In our own trials that we financed, you can look on the left hand panel which is looking at that thirty day KI sixty seven measurement where you see a drop from the initial numbers to the post thirty day numbers. Typically ten percent is a threshold that clinicians find especially attractive in predicting two and three year long term effects. And so you can see that we have substantially our patients going below ten percent. The right hand panel shows these same patients at three to four months where their MRIs are showing significant decreases in tumor size. So as I’ve indicated, we also have this potential of interacting with partnering with other drugs.

And the CDK foursix inhibitors are the mainstay. So if you think about ER positive breast cancer, you have the ordinary proliferation rate breast cancer which is the majority of the population. But maybe twenty to twenty five percent are above that in terms of their reproductive pattern. These women will not, we know now that they need something more than just endocrine therapy. And the whole space of CDK foursix inhibitors was developed for that population.

We now can see that we can partner very effectively with the CDK foursix inhibitors through some of the in vitro work that we’ve done. And this is an incredible opportunity for us because we know now, we have enough experience that when an estrogen receptor therapy is coupled with a CD four six inhibitor, CDK four six inhibitor, the outcome is that you will cause resistance to the estrogen receptor. And at that point in time, the estrogen component is no longer working. We believe we’ll continue to be active at that point in time. So from both the preclinical and clinical perspective, zeandoxifen is both safe and well tolerated.

So in the preclinical studies, the two major parameters that we like to see is that it does not reduce bone loss which is again very typical of some of the other estrogen receptor modifiers. And it doesn’t change uterine weight. Now why would that be important? Well it’s important because uterine weight change is a precursor to endometrial proliferation which is a precursor to cancers in tamoxifen. So they’re very rare, roughly one in ten thousand, one in fifteen thousand.

They only occur in postmenopausal women. They only occur in women with more than two years of treatment. But nonetheless, endoxifen seems to have a unique profile compared to tamoxifen which again makes 21 different molecules to show that at the very first start of that whole process that leads to cancer, uterine weight increase doesn’t happen. So that’s very gratifying for us. And of course, now in the clinic, zeandoxin has been tested at a lot of doses and just dosing is very important.

And this drug, again I’ve invented seven drugs. This drug has the broadest spectrum of dose that I’ve ever seen. So in prevention, we used one to two milligrams per day. In the clinic where you’re trying to prevent breast cancers, forty to eighty milligrams per day. But in the metastatic setting, it’s actually been used up to 300.

Cancer drugs typically have a maximum tolerated dose which is a dose where you go above that, you’re really hurting the patient more than you’re helping the cancer treatment. And Doxin doesn’t have one of those. And again, we may be very unique. The only drug or a small handful of drugs that do not have a maximum tolerated dose in the cancer space. So the metastatic setting we’ve seen, there’s again, other people have done activity to de risk our clinical programs coming up.

So the current programs that we have in prevention and neoadjuvant were summarized with abstracts at the San Antonio meeting last December. But just to remind you, in the prevention space, we were looking at women who had a high density and then took a sugar pill, had one milligram or two milligrams in a blinded fashion for only six months. And then we looked at the density reduction and we looked at the side effects. The density reduction between one and two milligrams was different but not statistically different. And the side effect profile between placebo and one milligram was not different.

The two milligram had a few more side effects than placebo. So if at a time, at a point in time when we will go forward with prevention, probably one milligram per day will be the dose that we will be using in that space. The Evangeline trial which looked at four week Ki67 with less than 10% showed that over eighty five percent of patients across the board had the reduction that, again, that ten percent threshold is something clinicians will look at and say, okay, I can predict two to three years that this woman is in a good place with respect to potential recurrences and the like. The I SPY trial which, backing up just for a detail. The Evangeline trial is in premenopausal women only.

So the I SPY trial in the same patient population with respect to disease is both pre and post menopausal women. So you can see we very strategically tried to again expand where this drug could have effect by having trials in different spaces to give us unique information. The I SPY trial reached its primary endpoint in ninety five percent of the participants who completed at least seventy five percent of the planned dosing. So again, remember that number of fifty percent of women who stopped taking drug is an indication here that that did not happen in this particular setting. And the mean KI sixty seven reduction was from ten point five to five percent, about a sixty five percent reduction over there.

And with respect to imaging, almost a seventy eight percent reduction in tumor size. This is important not only for knowing that you’re killing the tumor but it can change the surgeon’s treatment. He can go from having to do a mastectomy if it’s really large to maybe a lumpectomy to have the same clinical outcome but a different outcome for the woman in terms of quality of life. So this table summarizes the features and the various treatments. Again, I’m starting to repeat myself and you’re starting to hopefully understand the uniqueness of endoxifen.

It’s superior to tamoxifen which is its parent drug but which has 20 other materials that don’t have activity on cancers but can have activity in other spaces. And not all women can make endoxifen because they don’t have the liver enzymes to do that, those two step chemistry I spoke about. The aromatase inhibitors who, which are more effective than tamoxifen in classic trials but have a forty percent arthritis rate that many times can lead a woman to stop taking the drug because of its severity. And final fulvestrant, which is a monthly injection. It’s supposed to be very reasonably painful but is the gold standard with efficacy and which are, again, one of our KOL said, this drug may be, know, Andoxin may be as good as fulvestrant.

One of its challenges is that the week before your next injection, so you get an injection every month, you’re going to have trough levels where the drug decays. You’re going to have trough levels where the tumors will escape. And so having a tumor that’s suppressed for three weeks out of the month but for one week it’s growing again is not a profile that is attractive when you can give a single pill on a daily basis. So we have a number of upcoming events. I’ve indicated what we’ve done in this first half of the year was to very deliberately focus on what’s the fastest path to approval.

What is the group that can help advise us on that? We came to the conclusion that the metastatic setting is the best approach. There’s inside of that small statement, there’s 12 or 13 different inclusion exclusion criteria’s that can help define the trial. Those are now embedded in a document where we’ve sent to the FDA to say, this is our perception of the best trial to get this approved in metastatic. What do you think?

We will take their feedback, we will reincorporate it. In the background, this will be an international trial. It’ll be a trial that will be run by some of the standard CROs. So we are currently, without even having the results from the briefing meeting, we are currently vetting CROs for that process because it’s very important. They will be the lifeblood of getting us across the finish line with respect to patient recruitment.

And so, we’ll be reporting on these events in the third quarter and then into the fourth quarter. And remember, all of these trials, all the foundational trials in prevent, excuse me misspoken, in the neoadjuvant setting, we’ll be having reports out as they progress through the rest of this year. We have said publicly that it is our goal to have our first patient in our FDA approved registration trial by the end of this year. So that’s New Year’s Eve. Key statistics which you can find our cash position, 65,000,000 as of March 31.

It gives us two years of runway with our current operations. These trials will take more money than that particular conversation But nonetheless, we will be able to define very clearly, here’s the trial, here’s the CRO, here’s the FDA’s opinion, here’s the cost to help get that drug FDA approved. Market cap of about a hundred and 12. We have some outstanding warrants which are expiring in June, July and September. We have no debt on our balance sheet.

So again, let me summarize here. We have a multi billion dollar opportunity in ER positive breast cancer. We believe that we have the best drug in that case from both a scientific point of view with respect to killing cancers, from a safety and profile and quality of life point of view with respect to patients experiences with it. It demonstrates broad utility from preventing breast cancer to the metastatic setting and everything in between. We have a robust and expanding IP portfolio.

Take great pride in the IP of the companies that I’ve been involved with. I have 92 patents so hopefully that speaks to that. Very experienced leadership team inside the company and with respect to advisors and a strong financial position. Again, two years of runway on the balance sheet, no debt. And with that, I would thank you very much for your attention and appreciate you, your participation with Atosa Healthcare, excuse me, Atosa Therapeutics in preventing and treating breast cancer.

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