I am Anjli Venkateswaran, and it is my pleasure to introduce Valeriia Syrovatska who will be joining me today. Valeriia is a scientist at Biomere in Worcester, Massachusetts, and she focuses on developing flow cytometry panels. Valeriia received her bachelor’s degree from the Massachusetts College of Pharmacy and Health Sciences and her master’s degree from Brown University.

Biomere is a preclinical CRO with locations in Worcester, Massachusetts, Richmond, California, and multiple sites in China. The company’s portfolio includes comprehensive discovery, DMPK, and GLP toxicology services. You can learn more about Biomere’s service offering at www.biomere.com. So let’s get into today’s topic on preclinical flow cytometry services at Biomere. Welcome, Valeriia. How are you?

Hi, Anjli. Thank you so much for introducing me. I’m doing great. How are you?

Doing well. Let’s start with an overview of Biomere’s growing capabilities in the flow cytometry space. It’s definitely an exciting space. So let’s talk more about what you and the flow group are up to.

Sure. So just to preface, flow cytometry is a powerful analytical assay that uses fluorescently conjugated antibodies to track surface and intracellular targets. The most common applications of flow cytometry at Biomere are immune profiling and receptor occupancy.

Maybe we’ll talk a little bit on immune cell profiling—and, you know, because I think that’s an area that’s become really important, especially in immune oncology and autoimmune disease. So tell us a little bit more, what kind of studies do you do? I’m sure they run a range, but are there some studies that are more common than others?

The majority of our studies are immune profiling. Some of the most frequent studies we’ve been doing recently are LNP-delivered therapies and other drug-based treatments. We are looking at tracking inflammation, cellular uptake, and off-target effects. Flow cytometry is great for that because of the versatility it brings.

So essentially, what I understand is you’ve got your control samples and then you have your LNP-treated samples, and then you look at changes in immune cell population mix. So you see an uptick in NK cells or M2 macrophages or something like that. Is that kind of what you guys are doing?

Right. We definitely start with pre-dose samples, and we look at how the animal’s immune system looked before any therapies were administered. And then, usually, we look at a few time points throughout the study to sort of track the progression of the response. The animals have two therapies. So yes, we’re looking at, depending on the study, it could be T-cell or B-cell depletion or activation of certain markers, or even receptor occupancy.

Whether the target made it to the tissue that it had to get to. And that’s super important, right? Because if it’s like an antibody study or something that binds the cell surface receptor, you want to make sure that there is target engagement, so to speak. Okay, got it. So, you know, we talked about the samples, so what are the main sources of the samples? In other words, what are the tissue types and species that you work with primarily?

At Biomere, we work with a variety of small and large animal species. However, for flow cytometry recently, the majority of the studies focused on non-human primates in terms of the samples and tissue types that we get. The main requirement is for it to be a single-cell suspension. The most common sample we get is blood, of course, because that’s something that can be taken at many time points. It’s not an invasive procedure, so it can be used for longitudinal studies or even the fast ones. Blood would be the most frequent one. However, we also see a lot of bone marrow and even tissues like spleen and lymph nodes.

For those tissues—and that was what I was thinking—so seeing like spleen and lymph nodes, you would have to basically do some mechanical disassociation to make the single-cell suspension, right? Right?

Yes.

So, okay. But with peripheral blood, those are probably easy to process and kind of just handle.

Yeah.

And tell me a little bit about the volumes because when I think mouse and I think NHP, the first thing that pops into my head is, gosh, the sample volumes must be really different between a small animal and a large animal. Tell me more about that.

That, honestly, could be one of the reasons why we’re seeing more NHP studies than small animal studies. Although our instrument can accommodate smaller sample sizes, we still require a good number of cells in order to see population spread. I would say for the smaller side of the panel, we’re looking at at least one milliliter of blood, and that would give us anywhere between 1 and 3 million cells. Ideally, we will want a little more if we have a larger panel so we can accommodate all the controls, FMO, and anything that we need, and also allow for a good amount of events to register for the samples themselves. FMO is a fluorescence minus one. We have different types of controlling flow cytometry. One of those is fluorescence minus one. So basically, what it is we add all the stains in the panel except one, and that allows us to clearly gate out and define the population that is missing. Another type of control that we use is a single stain control, which is sort of the opposite of that.

Right, right, right. No, that makes sense. One is kind of like a negative, one’s kind of a positive. That makes sense. Right. Oh, very. That’s really, really, really cool. So speaking of instrumentation, I know Biomere has a really kind of cool flow cytometer, which is a CytoFLEX. Tell me more about that. And is that your workhorse instrument, and is that what you guys primarily use for all your studies?

Yes, that is the instrument that we use for all of our studies. It has five lasers and is very comprehensive. It can accommodate up to 21 colors. However, we like to keep it under 12 to 15 in order to make sure that we can produce good quality data with good spread out on the compensation. So yes, it is very versatile. It is very sensitive, so we can look into those smaller populations that clients are currently looking at.

Got it. Got it. And it’s pretty reliable and, and, um, basically you get data pretty quickly, don’t you?

Yes, we get data very quickly. Clients can expect raw files within 24 hours and analyzed data within two to three days, ideally, depending on the complexity of the panel that needs to be analyzed.

And I think that’s a really important thing to point out. I just want to pause here because, you know, one of the things I think is when clients—biopharma drug developers—are sending their precious drugs, whether it’s LNP vaccines, whatever therapeutic, this is the most important thing to them. So I think the fact that they get the data back so quickly must be really, you know, really encouraging and really positive because I think what I feel is what biopharma clients don’t like is the black box approach where they don’t quite know. They’re sending their drug, the therapeutic or a few candidates or whatever it is, outsourcing that and hoping and praying things look good. And then after a good amount of time passes, they get some data back. But the fact is you’re really depending on key data, and the fact that, you and your team flip the data around so quickly is, is amazing. That’s as close to real-time data sharing as possible. Did you say raw data in 24 hours and analyzed data in two to three days? That’s amazing. I think that’s something really noteworthy because flow data, from what I’ve seen, is often used to make a lot of decisions—go/no-go decisions, dosing decisions—and it’s really, really informative, right? So that’s, I think, really amazing. So I wanted to kind of—you mentioned something earlier about doing, you know, you can handle up to 12 to 15 colors, that’s amazing. But I’m going to be a little, like, I’m going to poke you a little bit and ask in terms of, you know, flow. A lot of the flow cytometry assays depend on the antibodies. Of course, if you don’t have the antibody, you really can’t run flow unless you perhaps use like some kind of stain or something. And, you know, you mentioned that Biomere, and I know that Biomere, has a lot of expertise, experience running primate studies. This is, this is, you guys are really, really good at that. And you mentioned that most of the studies are from NHPs. But tell me something, there’s not many NHP-specific antibodies out there, right? So how do you guys manage to match antibodies that work in NHP samples?

That’s actually a great question. So with the growing popularity of NHP studies, there have been a decent amount of NHP-specific antibodies popping up on the market. However, if a client is interested in a target that is not necessarily validated for NHP use, we would work with them to do a literature review and dig through the internet to find an antibody that has been reported to cross-react with NHPs, which most often would be human antibodies that cross-react. We would select a couple of those and then, prior to every study, we would run a test run where we would test the panel to make sure sensitivity and reactivity is optimal. And that sets us up for success for the downstream study time points.

And so, based on some of the work, you know, the panels that you’ve developed, some of the work you’ve done, I’m guessing you primarily use monoclonal antibodies, or do you use any polyclonals? We use both, but monoclonals are usually cleaner. 

And I think, you know, I was thinking back to some of the larger catalogs that I’ve seen. And I’ve looked for NHP, and often what I find is there are very few antibodies, for example, that are CD8, CD4, or something very basic that you can buy. But if it’s like a new receptor or a new target, I’m guessing that you have to work with the client. So that’s super cool that you do that. And you do some of your own validation, so that’s really, really great. And I think that speaks to the expertise that you have in the flow group, so that’s awesome. So I wanted to ask you, and this is kind of like my last question to you, is what do you see for the future? Like, what are some of the things that, you know, that you and the team are looking forward to? Or what are some new service offerings? Do you have, you know, any plans in the flow group for the future?

We’re definitely keeping up with the industry trends. We are looking into getting a Spectral Flow Cytometer. Spectral flow cytometry has recently gained a lot of popularity because of its high-parametricity and it can accommodate a much larger panel than a conventional cytometer, so we can go up to 40 colors with a spectral. So, we’re looking into that. And another thing that we are also really excited about is bringing a new application of flow cytometry to Biomere, which is looking at cellular uptake with flow cytometry. We have done it for a couple of clients, but we’re looking to bring it out to the larger masses, so to speak.

That’s awesome. I think that’s super exciting. And thank you so much, Valeriia. I think that’s awesome. It’s really encouraging to hear about what you and your team are up to and how Biomere is growing its capabilities, because I think a lot of  preclinical data is so important for the development of new therapeutics, and it really informs the clinical stage. So, thank you so much for your time. And to everyone out there, I hope you enjoyed this conversation with Valeriia Syrovatska. Again, if you’d like to learn more, please visit biomere.com. Thank you again, Valeriia. Thank you so much, Anjli, for having me. I had a great time talking to you. And thank you to everyone who tuned in. I hope you enjoyed it,