Laboratory diagnosis and management of hemophilia: Extended half-life concentrates, emicizumab and hemostatic rebalance agents

Welcome to today's session of the Hemostasis Learning Institute. I'm Doctor John Mitzios, Medical Sciences Partner at Siemens Health and Ears, and I'm your host today. Today's speaker is Doctor Steven Pipe. Doctor Pipe is a professor in the Department of Pediatrics and Pathology at the University of Michigan in Ann Arbor. His research has primarily focused on the field of hemostasis and hemophilia, particularly in Pediatrics. He has held numerous positions in both national and international scientific societies and has published almost 150 peer reviewed papers in renowned scientific journals. Extended Half Life, Factor 8 and Factor 9 concentrates, as well as Factor 8 mimetics such as a Mr. ZAP or Mimmate have revolutionized the treatment of haemophilia A&B, but these new therapies may significantly affect the performance of assays in the hemostasis laboratory, potentially causing misleading or false results. This lecture summarizes current advances in treatment and management of hemophilia patients and their implications for the Hemostasis Laboratory. Dr. Pipe, the floor is yours. Well, thank you for that introduction and I'm pleased to give this presentation on laboratory diagnosis and the management of hemophilia with a focus on extended half life concentrates, emacizumab and newer hemostatic rebalancing agents. These are my disclosures. The objectives today is to recap the hallmark of hemophilic bleeding as well as the diagnostic assays and then I'll review the efficacy of currently approved therapeutic agents and their limitations. And then finally, I'm going to introduce you to the emerging non factor therapies that attempt to rebalance hemostasis by targeting natural anticoagulant pathways. So joint bleeding is the hallmark of hemophilia. Joint bleeding or hemarthrosis as it is called, this is responsible for more than 70 to 80% of the bleeding episodes in patients who have severe hemophilia, those that have a factor 8 or factor 9 level that's less than 1%. And the trouble with recurrent bleeding into the same joint is this most likely will eventually cause a hypertrophic synovitis, progressive cartilage degradation and ultimately hemophilic arthropathy with significant impairment of joint function. So the modern goals of hemophilia therapy are not simply to manage the symptoms of acute joint bleeding, but to prevent joint bleeding as a mechanism to halt even the progression of joint disease. So we're going to be talking a little bit about why do we measure factor levels in hemophilia. So of course, this is important for the clinical diagnosis of hemophilia, but further, it allows us to assign disease severity. And we also use these assays to determine when patients have inhibitors. These are antibodies directed against the protein replacement therapy. We also use factor activity assays for the clinical management of hemophilia even when they're on regular therapeutics. We use these assays in order to guide dose adjustment of factor replacement for monitoring factor levels during treatment and with prophylaxis and then also to optimize factor dosing using pharmacokinetic guided prophylaxis. Now the assays that are available in almost all healthcare settings include the activated partial thromboplaston time where this can also be combined with a mixing study to exclude the presence of factor inhibitor. And then the factor 8 and factor 9 activity assays are one stage APTT based assays. And in clinical use these allow accurate diagnosis of hemophilia and accurate disease severity assignment, particularly a distinguishing between severe versus non severe hemophilia. But for a full diagnostic precision and evaluation of a patient with hemophilia, we do need some additional assays. We also utilize the chromogenic or otherwise known as two stage factor 8 activity assay. We also utilize factor 8 and factor 9 genotyping, Factor 8 von Willebrand factor binding assays, as well as molecular analysis of exons 18 through 25 of the of gene. Why are these important? Because this allows accurate phenotyping of patients with hemophilia A particularly and clarifying patients who have activity discrepancies when their factor rate is measured in a one stage versus the chromogenic assay. In addition, these other genotyping and functional assays allow us to distinguish mild hemophilia A from the Type 2 Normandy von Willebrand factor defect. Now let's shift our focus to what the overarching hemophilia treatment goals are. Modern therapy is designed to effectively treat bleeds, but maybe more importantly, to avoid a bleeds and avoid the complications of bleeding and ultimately to avoid progression of joint disease and from a HealthEquity perspective, to allow patients to achieve the life that they choose to live. Advancements in hemophilia therapies have enabled more effective management for many people with hemophilia, but they do not suit everyone. For several decades, we've been relying on protein replacement therapy with factor 8 and factor 9 clotting factor concentrates. From a legacy perspective, these initially were plasma derived clotting factors, but in the last three decades we have been using recombinant technology to produce recombinant factor 8 and recombinant factor 9. Now with additional bioengineering on the recombinant platform, we've been able to alter the pharmacokinetic characteristics of these recombinant molecules and we now have extended half life versions of recombinant factor 8 and factor 9. And these agents have been indicated for prophylaxis on demand treatment and surgical protection for people with hemophilia A or B without inhibitors. But a major consequence of protein replacement is an immune response to these proteins. And particularly in hemophilia A, up to 30% of patients will develop inhibitory antibodies directed against factor 8. And these preclude being able to continue to use factor 8 to treat bleed or for prophylaxis. So we have been relying on what are called bypassing agents. These includes a plasma derived activated prothrombin complex concentrate, which primarily contains the vitamin K clotting factors as well as a recombinant factor 7A. And these agents are available to people with hemophilate A or B with inhibitors. We have had in recent years the first non factor replacement therapy, a factor 8 memetic called emesizumab. This is a bispecific antibody which I'll tell you more about. And this agent is only indicated for prophylaxis in people with haemophilia A, with or without inhibitors. The World Federation of Hemophilia has set a goal for prophylaxis on a global scale to prevent bleeding in people with hemophilia while allowing them to lead active lives and achieve a quality of life that's comparable to non hemophilic individuals. They recommend that prophylaxis be preferred over on demand treatment for all people with hemophilia with severe bleeding phenotypes and in children, early primary prophylaxis with a goal of 0 bleeds is recommended in order to reduce the risk of the long term complications of having hemophilia. Now, the current prophylaxis regimens do not provide complete protection for people with hemophilia. Prophylaxis is recommended also prior to engaging in activities where there's a higher risk of injury and the current prophylaxis regimens can convert a severe bleeding phenotype to a milder phenotype. But these people may still experience trauma related bleeds, particularly in those with high levels of physical activity. So look to the right first. And this is showing the typical pharmacokinetic curve of protein replacement therapy. Using factor 8 as an example. And in the lighter blue line, we see that immediately after a factor 8 infusion, you achieve a peak, but within the subsequent minutes and hours that follows, you have a pretty steep decline of the plasma factor 8 level that's a consequence of its clearance from plasma. And with the standard Half Life Factor 8 concentrates, the Factor 8 level falls back to almost back to a baseline level within about 48 hours, in which case the patient needs an additional factory infusion. The extended Half Life factory products really don't change the paradigm here, although we get the benefit of the extended Half Life, but it's been a fairly modest extension of the Half Life. And here patients are dosing about every three days. And if you look at some of the targets here, we're trying to keep patients at least out of the severe range, so above a level of 1 to 3%. But optimally, we'd like to keep patients well above 3 to 5%. The factory mimetic that we're going to talk about provides a steady state level, but this is still down in a range of around 10 to 15%. And if we look at some of the recommended target factor 8 levels for various physical activities, for a patient who is just performing mild activities regular day-to-day, perhaps a target factor Level 3 to 5% is sufficient. But if they're going to be performing higher risk activities, factor levels well above 5% are probably required to prevent bleeding. If they're going to be in performing intensive physical activity, then those levels may need to be higher, 15 to 30%. And of course, if a patient is recovering from major surgery, we're maintaining levels that are pretty close to the normal range in the 30 to 50%. Although around half of people with mild or moderate haemophilia experienced joint bleeds, many of them are still do not receive prophylaxis. Now, what strategies have been employed to extend the half life of recombinant colliding factors? Pegulation or additional addition of polyethylene glycol conjugates reduces the interaction of the protein with clearance receptors. We can also take advantage of rescue of the protein that gets endocytosed from intracellular degradation pathways through interaction with the neonatal FC receptor, and we do this by conjugating the FC component of immunoglobulin or recombinant albumin onto the proteins. We can also enhance interactions with Vomala brand factor, single chain factor 8 variants and factor 8 variants that have optimized tyrosine sulfation. All of these optimize that interaction interaction with Vomala brand factor and can modestly improve the overall pharmacokinetic profile. In addition, expressing particularly factor 8 in a human cell line eliminates the presence of non human glycans that are decorated onto the factor 8 as part of post translational modifications and these also can have a modest impact on half life extension. With regards to a significant impact that makes a difference clinically, it's primarily the apegulation and FC fusion albumin fusions that that have had the most success in the clinics. Now this is going to give us an idea about where the relative risks are related to fracture levels. So this is a Natural History study of patients with haemophilia A looking at their risk of joint bleeds on an annual basis based on what their baseline factor 8 levels are. So for patients with severe disease who have less than 1% on the far left of the graph, they have the highest risk of joint bleeding. But patients who have levels between 1 to 3%, you can see the steep reduction in risk for joint bleeding. And this was the observation that really led to the initial drive towards prophylactic therapies and maintaining effector 8 through levels so that they're not lower than 1 to 3%. But with the availability of newer innovations including extended half life, we can now target levels that are through levels that are closer to 3 to 5% to have further impact on bleed prevention. But you can see when you get out into the mild range over 5% joint bleeding becomes quite unusual. And if we can maintain factory levels or at least factory equivalency that's above 10 to 15%, it may be possible to completely abrogate a joint bleeding at least outside of significant trauma. So traditional prophylaxis has been in the 1 to 3% range, but in recent years the call has been to optimize that prophylaxis to get into the three to 5% range. The new standard of care however is to push patients into a much higher levels. Now to do that with replacement therapy using proteins, factor 8 and factor 9 replacement, this really puts a lot of burden on the patient because these patients have to be have to receive these products intravenously and it just becomes increasingly challenging with their pharmacokinetics to rely on protein replacement therapy to push them into these higher ranges. If we look at the non factor therapies, these actually have a ceiling and giving higher and higher doses of these non factors does not increase the factor 8 equivalency. So this is also a limitation of the non factor therapies. Aspirationally, if we could get patients well above 15%, we think that this would prevent almost all joint bleeding and we have to look to newer innovations to get us to that level. So here is showing the comparison between the pharmacokinetics across the bottom of various platforms of therapy versus the pharmacodynamics or the hemostatic effect of the agent. So you can see with traditional protein replacement on the far left you see the sawtooth pattern of the peaks and troughs of protein replacement therapy and there is a corresponding hemostatic effect for those levels. The extended half life factors don't really change the paradigm. What it does allow is to reduce the burden for the patient. But with the non factor therapies, we're not replacing factor 8 with a drug like emicizumab and there's no factor level to measure for these agents. However, we do get a course, we do get a hemostatic a response from these agents that has affected prophylaxis and it's a steady state, a level as opposed to the peaks and troughs with protein replacement therapy. We're not going to talk about gene therapy today, but aspirationally this kind of gives us the best of both worlds because it's going to give us steady state expression of a factor, factor 8 or factor 9 that can be measured in the plasma and there will be a corresponding steady state hemostatic effect as well. So let's talk about mesizumab. So if we look at the top portion of this figure, this is showing the function of the activated factor 8 molecule. Components on factor 8 allow it to bind to the phosphor lipid surface. That activated phosphorus surface is coming primarily from activated platelets and factor 8A here acts as a scaffold to allow a factor 9A and factor 10 to come together, catalyzing the activation of factor 10 to factor 10A. The challenge that we've talked about so far is that using protein replacement to provide this function of factor 8 is limited due to the pharmacokinetic half life of factor 8, which is about 6 to 10 hours and thus we get the frequent peaks and troughs of protein replacement therapy. Emesizumab is mimicking this scaffold function of factor 8A. It's a bispecific antibody. One arm of the antibody binds factor 9A. The other arm of the antibody binds factor 10. This does bring factor 9A and factor 10 together and allows for conversion of factor 10 to 10A. But what we gain with emesizumab is a significant alteration in the pharmacokinetics. Because it's a a antibody, it has a very long half life of roughly 28 days. And after a loading period of weekly dosing with this antibody, it takes patients up to a steady state level. And as long as they can continue a dosing across three different regimens, they maintain steady state levels. And so we eliminate the peaks and troughs associated with protein replacement therapy. The studies have shown that emicizumab can be given weekly, every two weeks or every four weeks on a prophylactic basis. And really there's no difference between these regimens. They achieve a steady state levels of emicizumab in the plasma and across the ranges that are depicted on the left side of this graph. All of these levels are effective at providing prophylaxis for bleeding. In addition, there's really no difference between adult and pediatric plasma. Steady state levels and this is now also been confirmed in infants under 12 months of age. So as of again opposed to the factory placement therapies where we do see significantly shorter half life in pediatric and infants, we don't see that with Emacism M. The $1,000,000 question for this strategy is, is the efficacy for bleed prevention with emicizumab superior to what we have come to expect from clotting factor concentrate prophylaxis? And the Haven Three study actually confirmed the efficacy of weekly and every two week dosing across 10 bleeding endpoints in 152 persons with hemophiliae without inhibitors and showed a 68% reduction in annualized bleed rate for treated bleeds and a 62% reduction annualized bleeding rate for treated joint bleeds. As well as a higher proportion of patients with 0 bleeding over the follow up. Compared to how those patients did on their prior factory protein replacement prophylaxis. In addition, some patients came into the trial with active target joints. These are joints that were repeated bleeding despite prophylaxis with factory and they exhibited more than 99% of these resolved on emesizumab prophylaxis. The Haven Four study subsequently confirmed the efficacy of every four week dosing in 48 persons with haemophilia A with and without inhibitors, showing that all of these regimens can be effective. Now what about meeting some of the remaining unmet needs? Future treatments should aim to address these unmet needs and people with hemophilia, and we have a vision for the future of what prophylactic therapy could look like. So with respect to unmet needs, we still see breakthrough bleeds and joint deterioration even in patients who are on existing therapies, protein placement therapy as well as emesizumab. The expectations is we should be able to hopefully achieve 0 bleeds in the majority of patients and hopefully prevent joint bleeding. We're aiming to reduce the treatment burden with easier and less frequent administrations. The development of inhibitors is primarily associated with the protein replacement era, but we would like to have therapies that are available for personal haemophilia both with and without inhibitors obviously. And mesizumab is is the first that's been able to achieve that for factory with inhibitors. From a quality of life perspective perspective, we want to enable personal haemophilia to live active lives really similar to their non haemophilic individuals. And as far as access to treatment, we want therapies to be accessible to all persons with haemophilia. Now the current factory replacement treatments are subject to AV dub F imposed half life ceiling. So I mentioned these technologies for factory extension, FC fusion as well as a various polyethylene glycol conjugation strategies. These all have a modest impact on the half life compared to the standard half life comparator. All of these agents, regardless of the strategy extend the half life about 1.3 to about 1.5 fold compared to the comparator. And that's because all of these still are reliant on binding to Von Miliband factor for stabilization. And the portion of the factor 8 molecule that interacts with VW are the the primarily the C domains. And they interact with this portion of the von Millibrand factor molecule called the D prime D3 subunit. And so by binding to von Millibrand factor, this makes factor 8 subject to basically the clearance rate of von Willebrand factor. So if we want to increase the half life of recombinant factor rate beyond what the half life is of von Willebrand factor, we have to decouple a factor rate from binding to endogenous von Willebrand factor. So the first molecule that's been able to achieve this is a Phanisoctocog used to be called Bivol one in the clinical development program. And let me describe some of the feature of this of this molecule. The primary strategy here is to use the base FC fusion factor 8 molecule and then combine that with AFC conjugate of recombinant version of the D prime D3 unit from von Willebrand factor. So by combining these together, this locks factor 8 into a stabilized version, Plasma buffers it from the clearance and it doesn't allow factory to bind to endogenous fomalobrand factor. In addition, they have added these repeating polypeptide segments called extens and these are inserted into the molecule to further a buffer the molecule away from clearance receptors. They have engineered throm and cleavage sites so that when factory gets activated as part of hemostasis, it does a couple of things. It cleaves the extend units off of the molecule and then it also cleaves off the D prime D3 subunit so that the FC activated form of factor 8 is liberated from D prime D3 and then can participate in hemostasis. So how does this molecule perform from a pharmacokinetic perspective? A single dose of Afanosoctacogalpha actually results in a three to four fold longer half life than other available at factory products. So on the left you see a comparison in pink, 50 units of a standard half life factory 8 with a half life about 11 hours, same dose of an extended half life product. In blue you see the half life about 15 hours. But with a phanisocticog because of the dissociation decoupling from binding to endogenous von Willebrand factor, now we're able to achieve a significantly prolonged half life, about 43 hours. And most notably here I want you to pay attention that within the first four days after infusion, the patient's plasma factor 8 level can be maintained in the non haemophilic range. So we've never really had a therapy before at least factor protein placement that could keep patients in the normalized range for the majority of the week after a single infusion. Another, the next innovations that we're going to finish with relate to the concept of a thromancentric view of hemostasis. So on the left you have the typical procoagulants that Dr. throman generation that ultimately converts fibrinogen to fibrin. So factor factor 10, factor 9, factor 8, prothrombin etcetera. These are balanced on the other side by the natural anticoagulants in plasma and they include antithromic tissue factor pathway inhibitor and protein C and protein S So normally these are in a balance in their levels in plasma. And when coagulation is activated, we can generate sufficient thrombin to convert fibrinogen to fibrin, but not so much excess thrombin generation that it produces risk of thrombosis. When you have a deficiency of factor 8 or factor 9 in hemophilia, you have reduced the pro coagulants on one side of the balance, but the natural anticoagulants are all, all, they're still in full force. And this is what we've been striving to overcome with hemophilia by either replacing factor 8 or factor 9 with factor protein replacement with clotting factor concentrates or in the case of hemophilia A using emacizumab to substitute for factor 8. But we can also rebalance this without replacing factor 8 or factor 9 if we could reduce the levels or the function of any of the natural anticoagulants. So let me show you some of the strategies that have been used thus far. This is showing three of the main natural anticoagulants that are are controlling and regulating thrombin generation. Tissue factor pathway inhibitor acts early in the pathway and primarily targets factors 7A and factor 10A. Antithrombin targets factor 10A and thrombin and activated protein C regulates activated factor 8A and activated factor 5A and each of these now have clinical development programs targeting these to reduce their function or their levels in plasma. We have anti TFPI strategies which primarily use monoclonal antibodies to inhibit TFPI. There are anti thrombin lowering strategies using small interfering RNAs and a couple of different strategies to target activated protein C, So let's briefly go through each of these. So first anti TFPI approach. So TFPI is a Kunitz type serine protease inhibitor. It down regulates the generation of factor 10A as well as a 7A tissue factor and then in turn thrombogeneration and primarily using monoclon antibodies to target TFPI. These have advantages of having high bioavailability because they can be administered subcutaneously, they have stable pharmacokinetics. And because we're working on the the anticoagulant side of the equation, it really doesn't matter whether you have hemophilia A or B with or without inhibitors, they're going to be effective. The challenges are there's there's no assay to measure TFPI that's accessible for clinicians. The physiologic levels of this is is quite low. There are some concerns about risk of venous thromboembolism because low TFPI levels have been associated with this and other contexts. But keep in mind we're treating patients who already have a severely impaired thrombin burst because of hemophilia. Anti Tfpis also exhibit target mediated drug disposition and this means that more frequent infusions are required than expected from a typical monoclonal antibody and anti drug antibody development has been reported in the clinical trials. This is an example of a monoclonal by the targets TFPI marstacimab. In patients before they came on to prophylaxis with this agent, they were, these are the relative annualized bleed rates that they had. These patients were not on prophylaxis in this particular study, but what you can see on the right is during the treatment. With marstacimab, this is a highly effective prophylactic agent with many patients achieving an annualized bleed rate that's close to 0. The next one is antithrom and lowering antithromen. It's a natural anticoagulant and a major physiologic inhibitor of thromen as well as factor 10A and factor 9A. And using a small interfering RNA that you can target antithromen specifically in the liver and reduce antithromen levels and this restores thromen generation of people with hemophilia. It has a sustained effect. We can do reliable antithromic monitoring, so you can monitor the pharmacoid dynamic effect of this agent. This can be delivered subcutaneously. It has a low immunogenicity and again, the aim here is to be used in people with hemophilic A or B, with or without inhibitors. Challenges with this strategy, people with anti trauma deficiency are at increased risk of thrombosis. But again we're targeting this in patients who have a severely impaired trauma burst because of their haemophilia. There has been observations of transaminase elevations without clinical symptoms and this has been seen with other siRNA therapeutics as well. And so this may be because of these agents targeting the liver. Now we have seen some results from phase three studies from the use of this srna called Fituzuran. What you can observe here on the left are the change in the anti trauma levels with dosing. So across the top are patients who did not receive srna knock down or Fituzuran. But within two weeks after a single dose of Fituzuran antithrauma levels fall to about a 20 percent or so of the normal range. And accompanying this on the right panel, you can see that there is a substantial increase in peaks ramen generation. So this is showing this a rebalancing effect. Now this has proven to be again a very effective prophylaxis agent with a roughly 90% reduction in annualized bleed rate compared to patients who were treated on demand with clotting factor concentrates a factor factor 9 or a bypassing agents in the in the context of inhibitors. But the big question is how does it perform head to head compared to traditional prophylactic strategies with those agents? So in the prophylaxis study, what you see is on the left row are the annualized bleed rates for patients on both clotting factor concentrated placement prophylaxis or bypassing agent prophylaxis. Roughly a median observed annualized bleed rate of 4.4 in a minority of patients. About 16.9% of patients who experienced 0 bleeds on that prophylactic strategy. But when switched to a fituzer and prophylaxis, the antithromic knockdown help them achieve A median observed to ABR of 0. And now we see the majority or 63% of the patients experiencing 0 treated bleeds. So finally strategies to a target activated protein C, these anti APC therapies are targeting APC again to restore thromengeneration in people with haemophilia. APC is a serine protease that down regulates factor 10A generation and then in turn trauma generation through degradation of factors 5A and factor A day. So if you can target APC then we can restore thromengeneration. These agents include a bioengineered serine protease inhibitor that targets APC, as well as a new monoclonal antibody that targets protein C. These can be given subcutaneously because of their high bioavailability. They have a long half life and a low immunogenicity and again can be used in people team affiliate with A or B, with or without inhibitors. As with the other agents we've talked about activated protein C or protein C deficiency in humans is associated with an increased risk of venous thrombosis. But we're using this in patients who already have severely compromised trauma degeneration. APC has some additional functions in the inflammatory side as well as set of protective functions and so some have raised concern whether these strategies could impact some of those actions by impairing APC. Serpent PC, the control program is ongoing. It's shown so far that it's a well tolerated and it shows that it can prevent bleeding in persons with haemophilia. In this early study, the all bleed median annualized bleed rate was roughly a 2.2. So it's a, it's a highly effective agent. Patients experienced more than 80% reduction in their baseline bleeding rate after switching to this prophylactic therapy and there were no observed treatment related adverse events or treatment related elevations of D dimer in this early study. So if we could summarize these emerging non factor therapies, they all share key similarities that I think may improve the management of people with hemophilia. They're only intended for prophylactic therapy. So patients will still require concomitant use of other hemostatic agents for breakthrough bleeds or for surgery. And there we have to be careful because you're already rebalancing coagulation by targeting these natural anticoagulants. So if you're adding new pro coagulants like Factor 8 or Factor 9 or bypassing agent, we have to be careful about the risk of too much thrombin burst. These agents are effective in hemophilia A&B and can be used in people with and without inhibitors. So this increases the the treatment options across the board for the patients we managed in the clinic. Essentially, these products all have steady state pharmacodynamic properties, so they avoid the peaks and troughs between doses that we're used to. With the clotting factor concentrates, for the most part, they're all affected by subcutaneous dosing. So this reduces the burden over an IV therapy with the cladding factory concentrates. And they all for the most part have reduced frequency of administration compared to factor replacement therapy and bypassing agents. So all towards reducing the burden of prophylactic therapy. So what can we conclude from this? Well, despite advances in treatment, there are still unmet needs remaining for people with hemophilia Air B, with and without inhibitors. Novel hemophilia therapies utilize a variety of mechanisms for treatment, but they all have the same goal, to form a stable clot in preventing controlled bleeding. And emerging therapies have some novel mechanisms of action that might address some of the ongoing. Met needs for people with haemophilia and I'm looking forward to continuing to use these new therapies in clinical trials and hopefully ultimately in commercial use as well. Thank you very much.

60 40 20 15% 40% 10 15 >1% 17 90 80 70 50 30 25 33 41 49 57 65 73 00 100 120 18 19 100% 90% 10% 3.9 6.0 1% 3.6 2.8 24.0 18.00 19.00 17.00 17.0 15- 5- 4.15 0.00 18.0 15.0 24.00 Hemostasis Learning Institute presents Laboratory diagnosis and management of hemophilia: Extended half-life concentrates, emicizumab and hemostatic rebalance agents Dr. Steven Pipe Powered by hemostasis experts John V. Mitsios PhD, Medical Sciences Partner Siemens Healthineers Laboratory Diagnosis and Management of Hemophilia: Extended half-life concentrates, emicizumab and hemostatic rebalancing agents Steven Pipe, MD Professor of Pediatrics and Pathology University of Michigan, Ann Arbor, MI, USA SIEMENS Healthineers DISCLOSURE Consultant to Apcintex, ASC Therapeutics, Bayer, Biomarin, CSL Behring, GenVentiv, HEMA Biologics, Freeline, LFB, Novo Nordisk, Pfizer, Regeneron/Intellia, Roche/Genentech, Sanofi, Takeda, Spark Therapeutics, uniQure Objectives 1: Recap the hallmar 3: Introduce emerging non-factor therapies that rebalance haemostasis by targeting natural anticoagulant pathways 1: Recap the hallmark of hemophilic bleeding and diagnostic assays 2: Review the efficacy of currently approved therapeutic agents and their limitations M. Joint Bleeding: the Hallmark of Hemophilia · >70-80% of bleeding episodes in patients with severe hemophilia (FVIII/FIX <1%) occur in the joints . Recurrent bleeding into the same joint may eventually cause · Hypertrophic synovitis · Progressive cartilage degradation Hemophilic Arthropathy · Significant impairment of joint function Hemarthroses Synovitis Photos courtesy of Leonard Valentino, MD; Rush University Medical Center. Why do we measure factor levels? Clinical diagnosis1,2 · Diagnosis of haemophilia · Disease severity assessment Inhibitor determination Clinical management of haemophilia1-3 · Dose adjustment of factor replacement · Monitoring factor levels during treatment and prophylaxis · Optimising factor dosing for PK-guided prophylaxis Assays for Clinical Diagnosis of hemophilia Assays available in almost all healthcare settings1,2 Clinical use oid · Activated partial thromboplastin time (aPTT) Accurate diagnosis of hemophilia1,2 - Mixing study to exclude the presence of Accurate disease severity assignment an inhibitor - Severe vs non-severe1-3 Factor VIII/IX activity - One-stage (aPTT-based) assay Additional assays required for full diagnostic precision Chromogenic (two-stage) factor VIII activity assay2 Accurate phenotyping of patients with F8/F9 genotyping4.5 hemophilia A and clarifying Factor VIII/von Willebrand factor binding assays5 discrepancies between one-stage and chromogenic assay results3,5 Molecular analysis of exons 18-25 of the VWF gene6 Distinguishing mild haemophilia A from Type 2N VWD5,6 Hemophilia Treatment Goals To treat To avoid To avoid bleeding To achieve Speaker's personal opinion. bleeds complications joint the life they disease choose Advancements in haemophilia therapies have enabled more effective management for many people with haemophilia but they do not suit everyone Currently available haemophilia treatment options include: FVIII and FIX CFCs1 Bypassing agents2,3 Non-factor therapies4 Plasma-derived and Extended half-life recombinant CFCs (SHL) (EHL) CFCs aPCC rFVIIa* FVIII mimetic Plasma- derived CFC SHL rFVIII SHL rFIX EHL FVIII EHL FIX Indicated for prophylaxis, on-demand treatment and surgery* Indicated for prophylaxis People with haemophilia A or B without inhibitors B with inhibitors People with haemophilia A, with or without inhibitors "rFVIIa is Indicated for on-demand treatment and peri-operative management aPCC, activated prothrombin complex concentrate; CFC, clotting factor concentrates; EHL, extended half-life; F, factor; rFVIIa, recombinant activated factor VII; SHL, standard half-life. 1. Srivastava A, et al. Haemophilia 2020;26:1-158; 2. FEIBA Summary of Product Characteristics, EMC, 2021; 3. NovoSeven, Summary of Product Characteristics, EMA, 2021; 4. HEMLIBRA, Summary of Product Characteristics, EMA, 2022. EHL FVIII EHL FIX WFH goal for prophylaxis Recommendations Preventing bleeding in people Prophylaxis is recommended over on-demand treatmentHL FVIII with haemophilia while allowing for all people with haemophilia with severe bleeding them to lead active lives and Prophylaxis achieve quality of life phenotypes1 comparable to non-haemophilic individuals1 In children, early primary prophylaxis with the goal of zero bleeds is recommended to reduce the risk of long-term complications2 1. Srivastava A, et al. Haemophilia 2020;26(6):1-158; 2. Bertamino M, et al. J1 Clin Med 2017;6(5):54 Current prophylaxis regimens do not provide complete protection for people with haemophilia ·Prophylaxis is recommended prior to engaging in activities with a higher risk of injury1,2 Current prophylaxis regimens can convert a severe bleeding phenotype to a milder phenotype but these people may still experience trauma-related bleeds, particularly in those with high levels of physical activity3 on-factor therapies Recommended target FVIII levels for SHL and EHL FVIII levels4 SHL FVIII Target factor level 5%-15% Performing mild activity Time (days) Although around half of people with mild/moderate haemophilia experience joint bleeds, they may not receive prophylaxis5 EHL, extended half-life; F, factor; SHL, standard half-life. 2021;50:100852; 5. Kloosterman FR, et al. Blood Adv 2022;bloodadvances.2022007620. various physical activities4 Recovering from major surgery Target factor level 15%-30% Performing intensive physical activity (depending on the intensity of activity and previous bleeding history) FVIII levels Performing higher risk activity (versus mild activity) 40% - ing from major surgery Strategies to Extend the Half Life of Recombinant Clotting Factors Reduce interaction with clearance receptors PEGylation Rescue endocytosed proteins from intracellular degradation pathways through interaction with the neonatal Fc receptor (FcRn) Enhanced interaction with Von Willebrand Factor Elimination of non-human glycans Human cell line expression Pipe, Hematology (2016) Joint Bleeding and Hemophilia Severity Annual Number of Joint Bleeds 0 1 FVIII Activity (IU dL-1) CC-12 Traditional Optimization of 6 - New Standard of Care Aspirational Increasing burden Traditional Optimization of Ceiling for NFT efficacy Treatment of hemophilia: Standard of care vs future goals with gene therapy Factor EHL factor Non-factor therapy Gene therapy Haemostasis Ideal Factor level Time Peaks and troughs of factor levels (red) and provided haemostasis (blue) differ substantially between the classes of therapies EHL: Extended half-life; Modified from Arruda VR et al. Blood 2017:130:2251-6 FX A2 t1/2 = 6-10 hrs C1 C2 Phospholipid membrane FXa Kitazawa T et al. Nat Med. 2012:18:1570-1574; Sampei Z et al. PLoS One. 2013;8:e57479; Muto A et al. J Thromb Haemost. 2014;12:206-213; Emicizumab - Mechanism A1 A3 C2 1 C2 TA1 t1/2 = 28 days Mean steady-state trough concentrations Mean Emicizumab Trough Plasma Concentrations3 Adult (n =213) Pediatric (n = 60) Concentration(ug/mL) HEMLIBRA concentration (ug/mL) Mean (SD) Emicizumab Time (weeks) Time after starting HEMLIBRA (weeks) -O- Adult (n =213) -O- Adult (n = 213) 33 4 Adult (n = 213) Is the efficacy for bleed prevention with emicizumab superior to CFC prophylaxis? . HAVEN 3 confirmed the efficacy of QW and Q2W dosing on 10 bleeding-endpoints in 152 PwHA without inhibitors1 · 68% reduction in ABR (treated bleeds), 62% reduction in ABR (treated joint bleeds) and higher proportion of patients with 0 bleeds vs prior FVIII prophylaxis · Resolution of >99% of target joints . HAVEN 4 confirmed the efficacy of Q4W dosing in 48 PwHA with and without inhibitors2 1. Mahlangu et al. N Engl J Med. 2018; 379:881-22 2. Pipe et al. Lancet Haematol. 2019; 6:e295-305. Future treatments should aim to address unmet needs for people with hemophilia Unmet needs Expectations for future treatments PwH, people with hemophilia. 1. O'Hara S, et al. Haemophilia 2020;27:113-19; 2. Wilkins RA, et al. BMJ Open 2022;12:e052358; 3. Berntorp E, et al. Haemophilla 2017;23:105-14; 4. Warren B, et al. Blood Adv Breakthrough bleeds and joint deterioration1-4 Zero bleeds, particularly joint bleeds5 Treatment burden6 Easier and less frequent administration Development of inhibitors7 Available for PwH both with and without inhibitors Quality of life1 Enable PwH to live active lives (similar to non-hemophilic individuals)5 Access to treatment6 Accessible to all PwH Current FVIII Treatments Are Subject to a VWF-Imposed t1/2 Ceiling1 VWF binding to FVIII Technology for FVIII Conventional FVIII comparator t1/2 Fc fusion (rFVIIIFc) 19.0 h2 12.4 h VWF monomer Glyco-PEGylation (N8-GP) 19.0 h3 11.7 h Cys variant-PEGylation (BAY 94-9027) 18.7 h4 13.0 h D'D VWF multimer Amino group-PEGylation (BAX 855) 14.3 h5 10.4 h Increasing the half-life of rFVIII is ultimately dependent upon decoupling FVIII and endogenous VWF Courtesy Barbara Konkle, MD ISTH 2019 Congress 1. Pipe SW. Am J Hematol. 2012;87(Suppl 1):S33-S39. 2. Mahlangu J, et al. Blood. 2014;123(3):317-325.3. Tiede A, et al. J Thromb Haemost. 2013;11(4):670-678. D'D3 BIVV001: The First FVIII Therapy Designed to Break the VWF-Imposed t1/2 Ceiling BIVV001 Effects of Activated Thrombin Activated BIVV001 Equals rFVIIIFc-VWF-XTEN FC C1 VWF D'D3 domain to XTEN insertions to increase t1/2 VWF BIVV001 is an investigational product that has not been proven to be safe or effective; XTEN technology in-licensed from Amunix Operating, Inc. Single-Dose Efanesoctocog Alfa Resulted in a 3-4-Fold WFH 2022 Longer Half-Life than the Other FVIII Products WORLD 50 IU/kg rurioctocog alfa pegol (n=13) Baseline-corrected FVIII activity was determined by the 1-stage aPTT-based clotting assay PK Efanesoctocog alfa Fold versus: increase t1/2 = 43.3 h Octocog alfa (SHL) 3.5 to 4.5 hours Rurioctocog alfa pegol (EHL) 2.5 to 3.2 5.3 to 6.8 3.2 to 4.1 2 3 4 5 6 7 8 9 9 10 11 12 13 14 Mean (+SD) plasma FVIII activity (IU/dL) BIVV001 is an investigational product "PK sampling was performed over a period of 3, 5, and 14 days after the administration of octocog Lissitchkov et al ., WFH 2022 Congress CONGRESS 50 IU/kg octocog alfa (n=13) t1/2 = 15.4 h Days after injection 10 - Haemostasis depends on a balanced coagulation process that generates sufficient thrombin to prevent bleeding Fibrinogen Protein C FIX Protein S FVIII Prothrombin Thrombin Antithrombin TFPI PROCOAGULANT ANTICOAGULANT F, factor; TFPI, tissue-factor protein inhibitor. Negrier C, et al. Blood Rev 2019;38:100582. Haemophilia leads to insufficient thrombin generation that disrupts haemostasis FVIIIa agen nor -fa disrupts haemostasisicoagulant pathways1-3 AT APC Throm Blood clot 2. Butterfield J, et al. Mol Ther 2020;28:997-1015; 3. Weyand A and Pipe S. Blood 2019;133:389-98; 4. Mammen EF. Semin Thromb Hemost 1998;24:19-25. Rebalancing haemostasis agents are emerging non-factor therapeutics that aim to restore sufficient thrombin generation by targeting natural anticoagulant pathways1-3 Haemophilia A FVa + FV Fibrin a, activated; APC, activated protein C; AT, antithrombin; F factor; TFPI, tissue-factor protein inhibitor. 1. Maciean P and Tait R. Drugs 2007;67:1429-40; FVII Anti-TFPI AT-lowering Anti-APC FIXa Anti-TFPI therapies target TFPI to restore thrombin generation in people with haemophilia II a, activated; F, factor; TFPI, tissue-factor protein inhibitor. 1. Maclean P and Tait R. Drugs 2007;67:1429-40; 2. Butterfield J, et al. Mol Ther 2020;28:997-1015; 3. Weyand A and Pipe S. Blood 2019;133:389-98. TFPI - Mode of action TFPI is a Kunitz-type serine protease inhibitor which downregulates generation of FXa and FVIIa-TF, and in turn, thrombin generation1,2 Targeting TFPI . No assay to measure TFPI as the physiological evels are low3,4 . High bioavailability when administered SC3 Advantages Challenges . Low TFPI levels have been associated with an increased risk of VTE5 · Stable pharmacokinetics3 Can be used in people with Anti-TFPIs exhibit target-mediated drug haemophilia A or B, with or disposition - more frequent infusions are without inhibitors3 required than expected from a mAb2 · Anti-drug antibody development has been reported in clinical trials6 F factor; mAb, monoclonal antibody; TFPI, tissue-factor protein inhibitor; SC, subcutaneously; VTE, venous thromboembolism. 1. Chowdary P, et al. J Thromb Haemost 2015;13:743-54; 2. Butterfield J, et al. Mol Ther 2020;28:997-1015; 3. Mahlangu JN. Front Med (Lausanne). 2021;8:670526; 4. Lenting PJ. Blood Adv 2020;4(9): 111-2118; 5. Sidonio R & Zimowski K. Blood 2019;134:1885-7; 6. Shapiro AD, et al. Blood 2019;134(22):1973-1982. Marstacimab Prophylaxis: Reported Annualized Bleed Rate (Median, Pre-study vs. During Treatment) look-back treatment period Median Annualized Bleeding Rate Pre-Treatment On-Study Treatment PF-06741086 300 mg SC QW Non-Inhibitor PF-06741086 300 mg SC Loading + 150 mg SC QW Non-Inhibitor PF-06741086 300 mg SC QW Inhibitor Overall - PF-06741086 300 mg SC Total Courtesy Johnny Mahlangu, MBBCh, ISTH 2019 Congress AT-lowering therapeutic (siRNA) targets AT to restore thrombin generation in people with haemophilia a, activated; AT, antithrombin; F factor. 1. Maclean P and Tait R. Drugs 2007;67:1429-40; 2. Butterfield J, et al. Mol Ther 2020;28:997-1015; 3. Weyand A and Pipe S. Blood 2019;133:389-98; 4. Mammen EF. Semin Thromb Hemost 1998;24:19-25. AT - Mode of action AT is a AT is a natural anticoagulant and a major physiological inhibitor of thrombin, and factors Xa and IXa1,2,3 Targeting AT Sustained effect4-7 Reliable AT monitoring8 . People with AT deficiency are at Low immunogenicity9 increased risk of thrombosis2 Aims to be used in people with haemophilia A or B, with or without clinical symptoms have been reported inhibitors4 with siRNA therapeutics10-12