All right. Well, thanks very much everyone for joining us this evening or this afternoon if you're here in Colorado. Really excited to to be able to deliver this particular webinar to you because there really is quite a bit that's new and different and kind of exciting and fun about lymphoma treatment.

And, in general, I'm, I'm gonna try and sort of divide this into two large bits and, and the first bit is going to be what are some things that I might be able to change or do differently. Today, right this second. So what are some sort of new little bits of information that might help me tweak my existing lymphoma protocols or a few little tips and tricks that have come out recently that might improve either how I treat my patients or the quality of life for my patients or things like that.

And then the second bit will be a bit about sort of stuff on the horizon, stuff in the pipeline, which may be available in the states and in some cases in, in the UK. Or stuff that's somewhere sort of in the development path, that I want you to keep your eyes out for sort of moving forward in the next couple of years. So a little bit of both, some real practical stuff and then some stuff that's a bit more pie in the sky that I want you to look out for in the future.

So, my conflict of interest statements, so just, the things that you see in bold there, I will be discussing. So, I both work for and, and have stock options in a company called VETDC which makes a compound called Tanovia, which we'll discuss. And I also have received a research funding and I'm a stockholder in a company called Corvis Pharmaceuticals, that has a treatment for T cell lymphoma that we're investigating currently at, at CSU that I'll mention very briefly.

Oh, real quick, real quick recap of canine lymphoma. One of the things that we really like to sort of impress upon owners is it's really not an all or nothing kind of treatment. So this isn't one of those diseases where you can talk to the owner and say, well, you either treat it or you don't.

There's actually quite a variety of different kinds of treatments that can be, that can be undertaken. Depending on owner wishes, owner finances, owner travel constraints, etc. Etc.

Etc. And it is one of those situations where, to a degree, the more you do, the better the potential outcome. And I'm not gonna go through all of these possibilities, but I will hit a couple that are the ones that I most commonly will talk to owners about, to give them a nice spectrum of treatment options to choose from.

So one of them, of course, is corticosteroids by itself. And we do know that the majority of dogs who come in sick with lymphoma do feel better with corticosteroids on board. At least half of them, if not more, will have some amount of, of, of shrinkage in the size of their lymph nodes.

But we are generally talking about relatively short-term benefit. And as I say, up here, I really do consider this to be somewhat of a one-way street. So there's a, a nice little study that came out, it was presented at the, at the American College of Veterinary Internal Medicine last year that actually tried to look scientifically at, at what is the outcome of dogs who get prednisone alone.

And in a group of about 80 dogs that they studied, the average survival time was 53 days from the time they start the prednisone. And the reason that I, that I mentioned the one-way street part of this is that it does seem, and this has been shown in multiple studies, that dogs that are pre-treated with prednisone for a long time may not respond as well to subsequent treatments. So a few days of prednisone, while an owner is making up its mind or while you're arranging a referral or to order drugs in is probably fine.

But more than a few weeks of prednisone, and we do start to get worried about how well whatever we reach for next might work. It's not a lost cause, but it is something that I, that does inject a note of concern, and I'm usually very forthwith, with the owners about that. The fact that, hey, this may not be as, as effective if we do a bunch of prednisone first and then go in and try and do some other kind of treatment later.

One of the simplest, what I call middle of the road protocols for an owner who wants to do more than, than corticosteroids alone, but may not want to do something that's incredibly complex that requires a very, very large number of treatments and is, is quite expensive, is single agent doxorubicin. So doxorubicin is only given once every 3 weeks. It's given as a relatively quick intravenous injection, so it's not something that drips in slowly all day or requires any hospital stays.

Again, I have no idea what the cost would be in the UK, but here, each treatment's about $250 or so, and that's not just the drug itself, that's the entire visit. That includes the office visit and the blood test and the pharmacy fee, and the nursing fee, and the disposal fee and all that stuff put together. So again, given once every 3 weeks, if things go well, we plan to do 5 of those treatments.

And the literature suggests that the likelihood of seeing meaningful improvement is about 3 out of 4, about 75%. If you take all the dogs and put them together, the average duration of that improvement with the first treatment is generally in the neighbourhood of sort of 4 to 5 months. And when you factor in whatever the owners decide to do at the time of relapse, we're generally looking at average survival times in the neighbourhood of 7 to 8 months, with about a third of dogs making it to a year.

So quick, inexpensive, well tolerated, and again, a grand total of only 5 treatments. One study that we, that we did a bit, a bit ago actually was a randomised study that looked at whether the addition of oral cyclophosphamide to the, to the doxorubicin actually resulted in any kind of improvement in outcome. And the thought here was that a couple of extra cyclophosphamide pills really adds nominally to the cost, and it does not increase the number of treatments that are required because the, the cyclophosphamide and the doxorubicin are given concurrently.

And again, what you can see from these two Kaplan-Mer curves here is that there was certainly a trend toward the dogs receiving the concurrent treatment with cyclophosphamide having slightly better outcomes, but this was not statistically significant. So, could be a consideration, but we really can't use the results of this study to, to, to, to support unequivocally the fact that, that this addition is beneficial. So something to consider for the right owner though.

So, really for the past 20 years, the, the standard of care for the treatment of most forms of canine lymphoma has not changed. And these are generically what are called CO protocols, hence the acts that you see in the picture. And again, these are combinations of protocols that, that utilise the drugs doxorubicin, which we mentioned already, prednisone which you mentioned already.

And vincristine and cyclophosphamide. And you'll probably find 5 or 6 different iterations of this protocol published in the literature and published in different textbooks. They're all relatively the same as far as the outcomes that are achieved, they just simply mix up the drugs in different orders.

And what we generally will tell owners is to expect about a 90% likelihood of significant improvement. Take all the dogs and put them together. The average duration of that improvement is in the 7 to 9 months range, and by the time you factor in rescue therapy at the time of relapse, the overall median survival time is around 1 year, with about 20 to 25% of dogs living to 2 years.

What happens when you get to 3 years, 4 years, 5 years, Sooner or later, unfortunately, all but about 5% of dogs will eventually succumb to their lymphoma. So this is just an example of probably one of the more familiar of these COP protocols. This is called the UW Madison protocol.

Again, there's nothing magical about this particular protocol, but it's just a nice example of one that you can find in the literature. And again, we'll talk about a few little tweaks or differences between what's written here, which dates from about 15 years ago, to sort of what's, what's more contemporary at this point. So one of the recent changes is that there are some people who instead of, I'm gonna go back a slide here, instead of doing weekly treatments for the first two months and then doing every other week treatments after that.

Just simply continue weekly treatments for the entire 19 or sorry, the entire 16 treatments. And really, the, the literature suggests that there's no difference in outcome when patients are treated this way. So some owners like the fact that they can get the entire treatment regimen completed in a shorter period of time, which means that their dog has more time when they don't have to come in frequently for treatments or anything.

Some owners like the fact that it can be spaced out a bit more, if travel back and forth is a problem. So really, this is 100%, really, up to the individual owner and up to the individual vet as to which of the two sort of iterations of this protocol is most appropriate. And it's really purely based on convenience.

There's no difference in outcome. One of the things that we know, is a common, all too common actually, adverse effects associated with the administration of cyclophosphamide is what's called sterile hemorrhagic cystitis, which is an irritation of the bladder that really looks a lot like infectious cystitis, but as the name implies, it's sterile and non-antibiotic responsive. And this is actually caused by a metabolite of cyclophosphamide called acroline that appears in the urine.

And there's some very nice work that's been done to suggest that if you co-administer just a single dose of furosemide, that's standard 1 to 2 milligramme per kilo dose at the time the cyclophosphamide is administered, you can significantly decrease the risk of sterile hemorrhagic cystitis. So this is something that we will always do when we're getting bolus cyclophosphamide in a protocol like this is co-administer just a single dose of furosemide. So, one of the other sort of debates out there is whether there is any benefit to the administration of a single dose of asparaggenase at the very beginning of a protocol like the UW Madison protocol.

So many, if not most, of the original versions of this protocol did just that. So they always have this single dose of, of asparaginase that's administered in the very first week. And actually, a while ago, there were some brief periods of time where asparaginase was not available, at least in the US.

And again, this could be a few weeks here, a few weeks there. And during this period of time, there were actually two studies that were published that actually looked at either a COP protocol or UW Madison type protocol, and actually evaluated whether that single dose of asparaggenase at the very beginning had any impact on outcome. And the answer is it didn't.

So there was no difference in the outcome in either of these two studies between the dogs that got that single dose of asparaggenase and the dogs that did not. So based on these, on these data, really, at least at our institution, we tend to not administer that first dose of asparaggenase along with our CHP protocol and rather sort of save it in our back pockets for potential use at the time of relapse versus spending it up front. Another thing that's become a problem, at least here in the US over the past few years is that intravenous or, or injectable cyclophosphamide has actually become really prohibitively expensive.

So it went from about $60 a vial to about $500 a vial for no good reason. So, a lot of people made a switch to, giving the cyclophosphamide orally at the same dose. But up until recently, we really couldn't look at an owner and, and tell them that those two routes of administration were equivalent.

So thanks to some work that's been done actually here at Colorado State by our, our pharmacologist Dan Gustafson, we now know the answer to that both in dogs and in cats, and I'll share the dog data with you here. So actually what you can see is there's a fairly large difference in exposure to cyclophosphamide itself between the two routes of administration. So you actually see much higher levels of exposure to cyclophosphamide after IV administration than you do after oral administration.

But here's a little dirty secret, cyclophosphamide is actually a pro-drug. And the active drug is actually a drug called 4 hydroxycyclophosphamide. And when you look at levels of 4 hydroxycyclophosphamide in the serum of these drugs, there's actually no difference between the two routes of administration.

So you really probably can with Substitute an equivalent dose of oral cyclophosphamide for your injectable dose of cyclophosphamide and do that feeling comfortable that the, that the animals are gonna actually receive an equivalent exposure to the active drug. The same, the same thing has actually been shown in cats recently as well, so same thing holds true for cats. How about this situation?

So we certainly do encounter sometimes situations where we may not want a dog to have high doses of, of prednisone or prednisolone for a variety of reasons. So maybe they're already severely cushionoid. Maybe they have diabetes mellitus and you're afraid that the co-administration of prednisone is really gonna mess up their glycemic control.

I mean, these are things that happen all too frequently in our, in our older patients who often will have these kinds of comorbidities. So again, there are actually two studies that have been published recently. This is actually one.

Out of Utrecht, randomised studies that actually looked at whether inclusion of prednisone in this multi-agent injectable protocol made any difference. And in both of these studies, the answer was no. So it does appear that if necessary, you can omit prednisone from your sort of chop-based protocol or I guess it would be HO based protocol.

And it really doesn't tend to change the outcome in these patients, which is really nice to know. So then that begs the question, is it worth it to include prednisone for for your, your run of the mill lymphoma patient? And I tend to still include prednisone during the initial weeks of this kind of protocol.

And the main reason is I do think it tends to kind of keep them feeling a little better, especially during that period of time where we may see very, very rapid tumour cell kill. And as a result, some actually side effects, not as a result of the chemotherapy drugs themselves, but as a result of all the junk that's inside those cells spilling out into the bloodstream and potentially making them ill. So, I do tend to be a fan of continuing to use a, a brief tapering dose of prednisone for about the 1st 4 weeks of the protocol, despite the results of this study.

But again, I do feel very comfortable if I need to omit it for medical reasons that that can be done in a safe way and it's not going to jeopardise the oncologic outcome. So one of the major, major, sort of bones of contention among oncologists these days, really sort of hangs on this question, at least in dogs, about whether dogs with B cell lymphoma and dogs with T-cell lymphoma should be treated differently. So, it's been well established in multiple, multiple studies that as a group, with some exceptions, dogs with T-cell lymphoma tend to not do as well as dogs with B cell lymphoma.

And one of the first studies that actually sort of tried to look at, at this, a bit scientifically prospectively, actually looked at the response following a single dose of doxorubicin in dogs with either B cell or T-cell lymphoma. And actually in the dogs with B cell lymphoma, the likelihood of seeing improvement was 100% and 86% of dogs had a complete response just after that first dose of doxorubicin. However, in the T cell dogs, the overall response rate was only 50% and only about 1 out of 1 out of 7 of those dogs had a complete response.

So a very big difference, suggesting, wow, maybe we could be finding some way to do better for those dogs with with T-cell lymphoma. And again, for years and years, retrospectively, we've known that when we look at chop-based protocols, the T-cell dogs tend to be on the short side of the average mark. So, a few years later, There's actually a study that looked at a different kind of treatment protocol, so using what's called MOP, which again, as you can see here, stands for meclorethammine, vincristine, procarbazine, and prednisone.

And again, this is a protocol that's used for some kinds of human lymphomas and it's thought to potentially be more useful in, in certain kinds of T cell lymphomas. So one important thing to, to keep in mind here is that mecloretamine is actually a very dangerous drug to use. So this is essentially nitrogen mustard.

This is mustard gas from World War One, literally the same drug. So, again, unless you have the, the exact right and, and very sophisticated handling equipment for this, this is not a drug I would generally recommend administering in a general practise situation. However, when this kind of protocol was utilised, again, you can see the overall response rate was about 98%.

Medn progression free survival time was about 6 months, and the overall survival time is around 9 months. So not so bad, looking OK there. So that was kind of encouraging, but then the interesting thing was right around the same time, there was a group from California.

Who actually looked at a bunch of dogs with T cell lymphoma treated with chop. And this was just a very standard CHOP protocol, like I, like I showed you in that earlier slide. And again, the overall response rate was 96%.

Medium progression free survival time was about 5 months, not that different from 6 months. And the median survival time was around 8 months, not that different from 9 months. So probably statistically, exactly the same.

So very, very little difference there. Since then, There have actually been 3 additional protocols that have looked at these kind of alternative kinds of chemotherapy drugs specifically for the treatment of, of T cell lymphoma in dogs. And some of them have suggested a better outcome than what we are used to seeing with COP.

Some of them have not. Really, I think what the take home message is the jury is really still out on this. By no means would I say that it's wrong to try sort of some sort of alternative chemotherapy for a dog with a multicentric T cell lymphoma beyond CHP.

But by the same token, I don't think we have enough data to say, oh, you know, if you're not doing that, then you're sort of violating some standard of care, etc. So, here at, at Colorado State, we do tend to still stick with sort of a generic chop type protocol for both our typical B cell and T cell lymphomas. What we reach for, what we prioritise at the time of rescue treatment might be slightly different from our between our B cell lymphomas and our T cell lymphomas, but in general, what we reach for upfront remains exactly the same.

So very quickly, just a little bit of a recap about kitty cats. So one of the things that we know that's, that's really sort of changed about treating feline lymphoma in the last 15 years or so is we do know that there are now two very sort of distinct anatomic or sorry not anatomic but pathologic forms of feline lymphoma that we can encounter. Especially in the intestinal tract.

One of them is this sort of intermediate to high grade large cell form of lymphoma, and the other is this sort of small cell low grade form of lymphoma. And this distinction is actually incredibly important because the treatments and the clinical outcomes are actually diametrically opposed. So when we see these sort of intermediate to high grade forms of lymphoma, we generally think that these need to be treated with an injectable multi-agent protocol like what we would use for a dog, sort of a chop-based protocol.

And again, what we see is instead of that 90%ish kind of response rate that's observed in dogs, we see about a 60-70% response rate. About half of the responses are complete responses. About a quarter of the responses are partial responses.

Response to therapy is by far and away the most important prognostic factor in kitty cats. And again, if your cat with, with high grade lymphoma falls into the half of cats that has a complete response, it has the potential to do well for a fairly long period of time. Again, your median response duration is about 13 months.

But again, unfortunately, this is something that we only know about after we've started treatment. Contrast that with our low-grade GI lymphoma, where we can actually use a very conservative all oral chemotherapy protocol that generally consists only of oral prednisone and, and chlorambucil. And there are 3 different sort of schemas for the admission or the administration of the, of the chlorambusil that have been described.

One of them is, is 15 milligrammes per metre square daily for 4 days in a row, repeated every 3 weeks. So there is a single dose of 20 milligrammes per metre squared given every other week. And the third is a dose of 2 milligrammes per cat for the average sized cat unless they're very huge or very tiny, given every 2 to 3 days.

So all of these are associated with relatively equivalent efficacy. So about 85 to 90% of cats will approve symptomatically. And the median duration of that improvement is generally in the 18 to 24 month range.

So this is actually a very gratifying disease to treat. And again, very different from, from the way we would treat a high grade lymphoma, and similarly, again, a much simpler form of treatment as well. And, and very well tolerated and very efficacious.

This is why really in, in cats, it's, it's quite important to actually obtain a histologic diagnosis. Of our GI lymphomas rather than purely going based on cytology because generally cytology is not adequate to make that distinction between high grade and low grade lymphoma. So, what about that owner with a, with a cat that has intermediate or high grade lymphoma that again, wants to do more, but then just prednisone alone but maybe doesn't want to go the whole hog sort of chop-based every week sort of chemotherapy approach.

Is there sort of a middle ground or middle of the road kind of treatment for this in cats? Well, one of the things that appears to be less effective in cats and in dogs is single agent doxorubicin. So there are actually 2 or 3 studies.

That sort of have looked at this in the hopes of finding this sort of effective middle of the road protocol. And really, it does not appear to be very effective in cats, unfortunately. So that's probably not a good middle of the road protocol.

One other comment about doxorubicin and cats that you can see at the bottom there is unlike in dogs, we worry about nephrotoxicity, with doxorubicin administration in cats. So if we have a cat that, that already has some degree of renal insufficiency, we will avoid doxorubicin. And generally think about substituting my Zantrone in its place.

And during treatment with doxorubicin, even if it's in, as part of a multi-agent protocol, whenever doxorubicin comes up, we will generally check those renal values view and creatinine and urine specific gravity and make sure they're not creeping up, in which case we might need, might need to make a substitution to protect those kidneys. So Very, very recently, just last year actually, there was a paper out of Tufts University that looked at using single agent lousine, with or without a dose of asparaggenase at the very beginning for the treatment of these cats with intermediate to high grade lymphoma. And it really does appear to be a fairly reasonable quote unquote, middle of the road protocol.

So we're looking at a response rate of about 50%, about a quarter of which are complete responses. And again, if you take all of the responses and put them together, the median response duration is in the neighbourhood of about 10 months or so. So, is it as good as the CAA protocol?

No. But again, what we're generally talking about is a single pill, one pill given something on the order of every 3 to 5 weeks depending on how the blood work looks and a little bit of, of delayed neutropenia is the thing that we worry about the most, although it's rarely severe. So, this could be a very reasonable sort of middle of the road protocol to consider in a cat with intermediate to high grade lymphoma.

One more thing about kitty cats, and, and this has been shown in several studies, is that for, for some reason, cats don't appear to always tolerate vincristine as well as dogs do. So we very rarely see side effects from Vincristine administration in, in dogs, but in cats, actually, there's a fair number of cats who can run into some some gastrointestinal side effects from cristine. And this can be a little bit of vomiting.

More commonly, we can see, loss of appetite and, constipation or dyskesia as the side effects that we can see from vincristine. So actually, a group from University of, of Pennsylvania actually performed a prospective randomised trial looking at what happens if you take a cop type protocol, so the cyclophosphamide, vincristine prednisone and substituted viblastine for the vincristine. So interestingly, there was no difference in, in, in non-gastrointestinal toxicity.

There was no difference in outcome. The cats did equally well or poorly, depending on how you define that. But the cats who got the vimblastine actually had significantly less gastrointestinal adverse events.

They were actually reduced by about an order of fourfold. So I think this is a substitution that would probably be pretty reasonable to consider not only within the, the framework of a COP protocol, which again isn't done all that frequently anymore, or within the, the, the framework of a CO protocol. So when do when, sorry, then Christine comes up in that protocol, substitution for viblastine.

Maybe a very reasonable thing to consider. Again, here at Colorado State, we generally will still start, start with Vincristine because in our hands, the incidence of, of gastrointestinal adverse effects is not as high as what was reported in this paper. But again, if we do run into a cat that has issues, we won't hesitate to make this substitution for them blasting.

So, as I mentioned, in, in 95% of cats and dogs with lymphoma, sooner or later, we are going to be dealing with relapse. There are 5% of dogs that are probably truly cured. They'll live 5 years and die of something else.

But unfortunately, we really don't have any way to identify those dogs. So we really sort of coach owners to assume that their dog's eventually going to relapse and sort of what do we do when that happens? One of the things that I think is very important to impress upon owners is it's not necessarily the end of the road.

So this isn't sort of a one and done sort of treatment where there are definitely quite a few other things that we can offer. And one of the first things that we'll contemplate is, could this be an animal who could benefit from going back and doing the exact same thing again, going back and doing another course of chop therapy. And the answer to that is, yeah, under, under certain circumstances.

So our general sort of rule of thumb. Is that if, if they experienced a remission that lasted longer than about 3 months from the time that treatment was discontinued, not from the time we start, but from the time the treatment wrapped up. Generally, we think it's, it's pretty worthwhile to go back and consider doing chop again.

About 90% of dogs will have a second response. And again, a decent rule of thumb is that that second response is likely to be about half as long as the first response. One of the things that we worry about in the dogs is that If we got through 2 full courses of CHP, that would be a grand total of 8 doses of doxorubicin.

By the way, most people do these sorts of treatments and we do worry about cumulative cardiotoxicity from doxorubicin. Most of us feel a bit more comfortable if we don't go any higher than about 6 doses of doxorubicin. So normally when it comes to the 7th and 8th treatments when we would give doxorubicin, we'll make a substitution there and consider either midazantrone or sometimes Lomustine actually.

So just something to consider if you are doing this doxorubicin reinduction. Here's a study that actually looks sort of scientifically. At how well, sorry, Cho reinduction worked.

And again, the number one thing that dictated how well it worked the second time was how well it worked the first time. And again, so here are some numbers that you can see up there, but again, I think that rule, almost everybody's gonna respond, but it's gonna be about half as durable. Probably holds true for the majority of the situations.

So, in those situations where either we've been through this a second time or sometimes even the 3rd time and it's no longer working, or we got less than that sort of 3 months amount of time after we finished chop the first time, that's really the situation where we want to look for something different to try. And the list of different drugs and protocols that have been looked at for treating relapse lymphoma in dogs at least, is, is really quite extensive. But in general, if you sort of put all of the different drugs and protocols together, we'll say the likelihood of seeing another response is about 45% and the likelihood of a complete response is about 25% and the average duration of that response is about 60 days.

And I'll show you some numbers about that in graphical form just in a second. So this is a very, very long and complicated chart that really tries to summarise pretty much every single protocol that's ever been looked at for the treatment of relapse lymphoma in dogs. And again, the, the long and short of it is there are a whole bunch of things that have been looked at.

There isn't one thing that rises automatically to the very top of the list as being Obviously superior to everything else. Some of these are more complicated than others, some of them are more expensive than others. Some of them have a higher risk of side effects than others.

So really, there is not one magical treatment that everyone will agree is the thing that they reach for a second. If we actually do a little summary, And this is something I just did myself. It's not really all that scientific, but here we go.

One of the things that seems to make a difference if you have to choose a protocol is it does appear that multi-agent rescue protocols may be associated with a higher response rate. And actually a higher complete response rate as well than single agent rescue protocols are. So again, if we have a choice between one of this long laundry list of single agent protocols and potentially picking a multi-agent protocol, and you can see the multi-agent protocols are kind of on the bottom half of this graph or chart.

It does seem like you may get a little bit higher response rate from those multi-agent protocols. But interestingly, statistically, the duration of response when it's been reported does not seem to be significantly different between the multi-agent and the single agent protocols. So something to keep in mind there.

So a question I get all the time is OK, I, you know, I understand, Doug, that there is no one single magical protocol that everyone uses in this sort of rescue situation, but what do you do? So, one of the protocols that I tend to reach for in this situation is this combination of asparaggenase, CCNU or Lomustine and prednisone. You'll sometimes see this, see this referred to as a lap LAP protocol in the literature.

And this is sort of how that's done. So again, Lomustine is simply given once every 3 weeks. It's oral.

Asparaggenase is given along with the Lomustine for the 1st 2 treatments, and then it's discontinued, although the Lomustine is continued. Again, we do another prednisone taper and if we're really lucky and we see another complete response, we'll generally do 5 of these treatments and then quit. The one thing that is not on this slide, that is something I would do slightly different is that I do generally tend to co-treat these animals with, again, there's a nutraceutical that's available here in the states.

I don't know if there's an equivalent in the UK called Denimarin. It's a combination of aiddennocele, methionine, and silimarin. And there's a very nice again randomised prospective trial that actually shows that administration of Denimarin along with Lomustine tends to keep the liver a bit happier.

So you're less likely to have to make dosage adjustments, to give them breaks to keep the liver happy, things like that if you co-administer this Daimarin or again, potentially an equivalent supplement that contains the same two ingredients. So it's something to consider there. So looking at this LSPAR CCN new prednisone protocol, the likelihood of seeing another response is about 85%.

So better than average, and about half of those responses are complete responses. But again, median response duration, if you put everybody together about 60 days, about the same as everything else. So, again, this is generally very, very well tolerated.

It is not tremendously expensive and it only requires a visit once every 3 weeks. So from my perspective, I do think it's a pretty reasonable, pretty reasonable thing to consider, as a treatment for these guys, in that second line setting. So, now we're gonna switch gears and actually spend the next 15 or 20 minutes talking about some new treatments that are sort of somewhere in the pipeline, and sort of how they work and why they work and what's the data that we have so far that suggests that they may be useful.

And again, how long is it gonna be before before we can get our hands on them. So let's just sort of go through this list and I'll let you know sort of where, where all of these treatments are at, and how we may see them use in the future. So the first one that we'll talk about is a really, really interesting drug.

This is a drug called KPT 335 and this is an inhibitor of a protein called exportin. And Exportin. As a protein whose job, as, as you can see from the little cartoon there, is to actually pump different proteins out of the nucleus and into the cytoplasm.

And there's a whole bunch of proteins and some of the ones that you see down here, P53, RB, P21, stat 3. So a lot of these proteins are what are called tumour suppressor proteins. And when they're in the nucleus, they can actually help to keep cancer under control.

One of the ways that certain kinds of cancer appear to sort of subvert this process is instead of by genetically inactivating these or you know, turning them off by some other way, yup, they're produced, but then they're just pumped out of the nucleus so they can't do any good. So there are multiple tumour types in both dogs and humans where this, this protein exporting appears to be much higher in cancer cells than in normal cells. And in quite a few human tumours, the higher exporting one levels are, the worse the outcome is with that kind of cancer.

So really interesting potential target for treatment. And KPT 335 is actually a molecule that inhibits exporting. So when exporting is inhibited, all those proteins that are helping to control cancer growth instead of being pumped out of the nucleus, stay in the nucleus where they can actually do their job.

And again, as, as we can see with lots of chemical. If you dump enough into a petri dish, you can actually inhibit the growth of canine lymphoma cells. You can actually also inhibit the growth of a variety of other kinds of cancer cells as well.

In this case, we've got two osteosarcomas and a, and a mass cell tumour cell line as well. So this has been looked at in two different studies in dogs with cancer. One was all comers type study and the other was a lymphoma trial specifically.

And gastrointestinal toxicity is the most common toxicity that's observed. And in this initial study, There were actually 4 dogs that had partial responses and they were all dogs with lymphoma. And then 12 dogs that had disease stabilisation that ranged from about 4 weeks to about 12 weeks in duration.

So in, in vitro, again, there's activity against other kinds of cancer cells as well. And here's just a really neat image that actually shows you, one of these target proteins, P53, and, in the, in the control situation, P53 is kinda all over the place within the cell. So this blue dye is actually your nucleus here, so you can see, there's an awful lot of it that's actually outside the nucleus.

But after you treat with KPT 355, you can actually see that most of P53 is now localised to the nucleus, and this is where it can actually do good, causing growth arrests and even cell death. So really exciting proof of concept that this drug is working the way it's supposed to. And there has been a second study done with the same, drug, specifically in dogs with lymphoma, that actually suggested a significantly higher response rate, response rate more in sort of the 50 to 60% range.

Unfortunately, these responses were quite brief in duration, however, the average response lasted only about a month. The second drug that we'll mention is a drug that has gone by a bunch of different names over time. And, the brand name for this medication in the United States is Tanovia, which is the bottom one that you see here.

And Tanovia, rather than being sort of a targeted agent or something like that, is actually a cytotoxic drug. So this is a guanine nucleotide analogue. So it looks like the DNA base pair of guanine, and when rapidly dividing cells, sort of take up this funny looking guanine, it messes up the replication machinery in a way that causes DNA strand breaks and results in the death of the cell.

This particular drug, actually is a pro-drug that requires two different steps of activation. And the reason that this has been done is because the actual active compound PMEG is quite toxic. But if you administer this non-toxic pro-drug, it's actually converted into PMEG specifically inside lymphocytes.

And rapidly dividing lymphocytes like you see in cancer are the most sensitive because they're the ones that are, will incorporate the most of this PMEG into their DNA as they're dividing. And this is a drug that has conditional approval by the US Food and Drug Administration for the treatment of lymphoma in dogs. So, one of the sort of nice things about this drug is that there's actually quite a large body of information, that again now, is looking at over 650 dogs with lymphoma, to actually look at the efficacy and safety of this drug in dogs.

And again, you can see, many of these have actually been published in the peer-reviewed literature, several others have been presented at national meetings, and we'll just talk a tiny bit about some of the studies that have been done. There's some ongoing studies as well. So there's a dose finding study in cats currently, enrolling right now.

So, it would be a violation of the label and a violation of US federal law to give this drug to a cat, as things currently say, but again, this is being done in the context of a clinical trial that's sponsored by the company. There is a study that's looking at multiple myeloma and various leukemias, and actually there's a study that's been reported looking at co-administration of asparaggenase. Along with, tannovia as well.

So, one of the studies that's been published recently looked at two different doses of tinovia, specifically for dogs with B cell lymphoma that had failed chop-based therapy. And again, what we can see is if you take the two different dose levels and put them together, overall response rates about 75%. The median response duration is about 6 months, so considerably longer than what we observed with most of the other rescue protocols, which is kind of interesting.

However, keep in mind that these are only dogs with B cell lymphoma. And, we do know that dogs with B cell lymphoma do tend to do significantly better with this drug than dogs with T-cell lymphoma, much like what we see with most other forms of lymphoma. So it's a little bit of apples and oranges, but still something that looks quite intriguing and quite powerful.

A second study, which is also very interesting, looked at alternating doses of tannovia and doxorubicin for the treatment of previously untreated lymphoma in dogs of both B and T cell phenotype. So the overall response rate was about 80%. And the overall progression for intervals, so if you took all the dogs and put them together, was about 200 days or so.

So between 6 and 7 months. And actually, this compares quite favourably with contemporary reports of Chop-based protocols for the treatment of naive lymphomas. So, But again, the potential advantage here is that this is a total of 3 doses of each.

So a grand total of 6 treatments versus again, depending on how it's done 12 to 16 treatments with the Chop-based protocol. So an interesting observation and actually there is a second confirmatory study ongoing that's gonna actually repeat this to look and see if if the same data can be generated a second time, in which case, really quite interesting and something that could be a consideration, especially for those owners who may have to travel a great distance for the treatment of their lymphoma, where weekly visits are quite impractical or challenging for them. So, moving on, let me just go back for one second.

So, again, Tanovia is a drug that is available in the United States. I do know that there are some folks in the UK who have been able to successfully import this drug. I do not know the details about how that, how that takes place or what type of rigmarole needs to take place in order for that to happen.

But again, if you talked with one of your local oncology specialty clinics. They can probably give you some information about a, whether they've done that and B, what the process was. I know it's feasible, but that's all I can tell you.

I don't know the details. So, monoclonal antibodies are really interesting, new field of investigation in in dogs with a variety of different kinds of diseases. So, at least here in the states, there's a monoclonal antibody that's now approved for the treatment of adiine in dogs.

It's an anti CD31, I'm sorry, anti-IL 31 antibody. There's an antibody for pain that's approved as well that targets nerve growth factor. And about 20 years ago or so, there was an antibody approved for the treatment of human B cell lymphoma.

That targets a molecule called CD20 that's on the surface of all different kinds of B cells. And this was really the one of the largest improvements in treatment outcome that's been seen in the treatment of human lymphoma in quite a while. And one of the really interesting things is despite the fact that this drug, which on the human side is called rituximab, has been looked at for almost 20 years, they really still don't have an precise idea about how it works.

So 3 different possibilities are listed here. So some people think that the binding of this antibody to the cell surface actually flags that cancer cell for destruction. By the immune system, either through either through the recruitment of cells like monocytes and macrophages or through fixing of complement.

And there's some studies that suggest that the the coligation of multiple CD20 molecules on the surface of these B cell lymphoma cells can actually cause the cells to die without any other, without any other influence from outside. So all these are possible, but again, even after 20 years, they don't know exactly how it works. How well does it work?

So here's what you can see, So this is just one of a bunch of different studies that were done in humans with diffuse large B cell lymphoma, which is one of the most common kinds of lymphoma that we see in dogs. So you can see the average progression free survival time almost doubled. With the addition of rituximab to standard chop-based treatment.

So, pretty exciting finding and again, this is really the standard of care for most people with B cell lymphoma these days. So, A couple of years ago, I think it was 2014, there were two monoclonal antibodies that were actually conditionally approved by the US Department of Agriculture for the treatment of B cell lymphoma in dogs. One of them was a rituximab-like, supposedly CD20 antibody, and another was an antibody that targeted a different protein called CDN 52, which might be present on, on T-cell lymphomas.

So this was approved based on primarily safety, to say, hey, we could make this stuff in a way that's repeatable and we gave it to some dogs and nobody got hurt. But despite the fact that these were approved and actually available for sale in the United States, the company that made them actually published some data after the fact, suggesting that neither of these two antibodies actually improved the outcome. In dogs with lymphoma, and that neither of them actually probably bound to the kinds of cells in the blood or in the body that they were supposed to bind to.

So despite the fact that there was a lot of hype and everybody got very excited about the, the possibility that this could be useful, at least these two particular antibodies do not appear to be very useful or specific for their intended targets, unfortunately. That being said, Elanco, which is again the, the division of Eli Lilly and Company that, that sells animal health products, has another B cell, specific monoclonal antibody that actually looks very good in normal dogs and has been shown to have some very nice effects in mouse models of, of canine lymphoma. So stay tuned for that.

That may be something that's coming up in the near future. Another way to target TCD20 which is quite interesting is, what if instead of administering an antibody to the patient, you make the patient create their own anti-lymphoma antibodies. So this is an approach that's been used successfully for the melanoma vaccine, what's called the OnSE melanoma vaccine that you may know about that's approved for the treatment of canine melanoma.

But a very similar approach targeting again, CD20, the same B cell anti antigen, is being looked at, to treat canine lymphoma. So everybody gets treated with a chop-based protocol with or without this, this, vaccine, to encourage the, the body to make its own CD20 antibody. And again, there's a trial underway right now looking at the efficacy of this protocol.

The data has not been made publicly available, but this may be something that's quite interesting and worth considering in the very near future. So, another drug that we'll mention very quickly is a drug called RV 1001. And this is a drug that that targets a cell signalling molecule called PI3 kinase.

And PI3 kinase is an intracellular signalling molecule that's very, very important for sending signals into the cells, telling them to do things like proliferate, survive, grow blood vessels, a bunch of things that are very, very important for cancer growth. And interference with this pathway has the potential to result in inhibition of, of cancer cell growth or even cell death. And again, this particular form of the enzyme, PI3 kinase delta appears to be especially important in lymphoma cells.

And again, this has been looked at in dogs with lymphoma. This is what's called a waterfall plot. I'm gonna, I'm gonna kinda skip this part of this cause I'll show you a different one in the next slide.

But just show that when you administer this drug, you can actually interfere with this intracellular signalling. So you see this black or grey band goes away and that's really suggesting that you're turning off signalling downstream of PI 3 kinase, and these are in tumour cell samples after treatment. So in actual patients, so pretty exciting there.

And again, this is what's called a waterfall plot. So this actually looks at how much the tumour size has changed over time following treatment. And you can see a fair number of dogs, about 70% of patients actually had significant tumour shrinkage after treatment with this drug.

And it's actually a very nice mix of dogs with both B cell and T-cell lymphoma, which is actually really neat to see and quite encouraging. But however, Again, the, the little downside to this is that the average amount of time that these treatments or that these responses persisted for was really on the order of about a month. So fairly short duration.

So, this is something that again is continuing to be developed, but what we think is that it's much more likely to be useful when it's combined with other stuff rather than when it's being used by itself. One very quick last one that I'll mention that's even a little earlier in the pathway, is a drug, that, that we're studying, that's called CP 596 or CP 808. And this is a drug that actually interferes with signalling through the T cell receptor.

And we know that at least some T-cell lymphomas still require signalling through that T cell receptor in order to stay happy and proliferate. So a few years ago, we actually studied a a molecule called iruinib, which inhibits signalling through a protein called BTK which is very important in B cell lymphoma. And we actually saw, there were a fair number of dogs who received this treatment that actually had meaningful improvement with their B cell lymphomas, and that drug is now approved for the treatment of human B cell lymphoma, as are a whole bunch of other drugs.

These are all in humans. But these are all drugs that actually work by interfering with B cell receptor signalling. So up till recently, there really wasn't an equivalent drug that could inhibit inhibit T-cell receptor signalling.

I'm just gonna skip this. This is just the data with this B cell receptor drug that we published. But there's a similar molecule called ITK.

That actually signals in T cell lymphomas and tells them to grow and survive and divide and things like that. And we're actually evaluating an ITK inhibitor for the treatment of T cell lymphoma in dogs. And at the time we made these slides, 3 dogs had been treated, so this was given twice a day at home.

We've seen no adverse effects from the treatment and we've seen clinical benefit in 3 out of 3 dogs that we've used it in so far. So this is a little dog named Chloe, a boxer with a multicentric T cell lymphoma who had almost a complete response following treatment with this with CP 596. Here's a second dog.

This dog had mucocutaneous T-cell lymphoma, who had a quite dramatic improvement of again, you can see their nasop plenum and their oral mucosa lesions just in 14 days. Unfortunately, this dog went on and, and died about 7 days later from metastatic hemangiosarcoma that we didn't know it had. The third dog actually, was a dog with cutaneous T-cell lymphoma that had a response for about 5 months.

And that dog actually had a complete response. So very exciting new drug that is just starting to enter human clinical trials right now and we're lucky enough to be able to actually expand our current study out of just Colorado State University, but to another 4 sites around the United States. And again, if things go incredibly well, it's possible that there could be a drug like this that is broken off and developed for the treatment of of canine.

T cell lymphoma as well, which could be very, very exciting. This, this type of drug may also be very useful as an immunosuppressive, so it could have use in autoimmune and inflammatory disorders as well. And with that, we're at about 25 past the hour.

And I, I'm gonna sort of quit at this point and I would be happy to take any questions that anyone has, and thanks very much for your attention. Thank you very much, Doug. Absolutely brilliant talk, really, really good.

So we do have two questions so far. So one is from Greg. Is it important to differentiate between B cell and T cell lymphoma when it comes to determining which protocol to use?

In the UK, the staining for this from the biopsies is quite expensive for the owner, so is it worth doing? Yeah, great question. So, I think it really depends on your owner's goals.

As I, as I mentioned during the talk, at least here at Colorado State University, our choice of first line treatment for, our routine dog with, with multicentric lymphoma is not different between a dog with B cell lymphoma and a dog with T-cell lymphoma. Again, there are other, other practises who do treat them differently. So from that perspective, it depends a bit about where the dog is going to be treated.

Again, at, at our institution, it doesn't tend to make a difference. However, one of the pieces, one of the things that it does do is give the owner more information about what to expect with treatment. So we do know that again, statistically, most dogs with T-cell lymphoma.

Will have an inferior prognosis to most dogs with B cell lymphoma. So those T cell lymphoma dogs do tend to be on the short side of those, those median values that I mentioned. And for some owners, that kind of prognostic information is information that they may find very valuable.

And for some owners, it could influence how they choose to treat, not because the options that we're providing are different, but because the owner may say, well, if my dog has a pretty good prognosis, I'll, I'll be more inclined to treat aggressively versus if my dog has a very poor prognosis. So again, really depends on how the owner is going to utilise that information as to whether it's a value for that individual patient or not. And that's generally how I frame that discussion with owners.

Excellent, thank you very much. And another question just asking, what is PTEN in your slide? Ah, let me go back to that slide.

And so in this slide, P10 is a, is a, is a tumour suppressor gene. It's a protein that's a negative regulator of this pathway. So in other words, high levels of P10 shut down signalling through this PI3 kinase pathway.

And interestingly, P10 is one of the most commonly mutated genes in the entire human cancer genome. So it's very, very common for this gene to be inactivated in human cancers. And to the extent that it's been looked at in canine cancers, mutations in P10, also seem to be actually quite common.

And what that suggests is in many forms of canine cancer, activation of this pathway may be very important. And again, treatments that are directed against signalling through here could be quite useful for a variety of different kinds of cancer, not just lymphoma. Lovely, thank you very much.

That seems to be all of the, another one. Can you stimulate P10? Ah, can you stimulate P10?

So, to my knowledge, to my knowledge, no one has, sort of looked at, approaches that would actually make P10 work better. There is actually another molecule that does a similar job to P10. That again is another suppressor of this pathway that is actually stimulated by the anti-diabetic drug metformin.

So metformin, which is again a human drug that's used to treat type 2 diabetes, can actually shut down this pathway through regulation of another protein. And there certainly are some folks who have been looking at whether metformin could be a useful cancer treatment. And I've actually looked at whether people who are on metformin for diabetes control might have differences in outcome with their cancer.

And there are some studies that suggest that the answer might be yes, that if you are administered metformin for diabetes, you could actually do a bit better with your cancer than if you're not. So an interesting target, distinct from P10, but again, a target that actually does the exact same job that you can stimulate. Lovely, thank you very much.

And does Metformin ever get used in lymphoma? Yeah, so as far as I know, no one has looked at the use of metformin for the treatment of lymphoma. The only study in dogs that I'm aware, or sorry, the only study in animals that I'm aware of was a study that looked at metformin, in cats actually, with cancer.

That was done at the University of Illinois, and they certainly were able to establish how much metformin was safe to give to kitties, but never really got to the point of being able to say whether it did any good or not. Mm, OK, lovely. Thank you very much.

And other than just a couple of comments, just to say what an excellent talk this was, which I have to agree it was really, really great to listen to. It looks like that's the end of the questions. So I'd like to thank all of our attendees for logging on and listening tonight, and a massive thank you to you, Doug, for your time and thank you again for such an excellent webinar.

Well, thanks to everybody for your, for your time and your attention this evening and I hope everyone has a good night.