An Overview of the Hemophilia Treatment Paradigm - Episode 17
Hemophilia: Clinical and Patient Perspectives on Emicizumab
Doris V. Quon, MD, and patient Eric Mamos provide their perspectives on Eric’s experience on the HAVEN 3 clinical trial with prophylactic emicizumab.
Doris V. Quon, MD: Let’s segue into your past treatment, which was using factor as you needed it or, as we call it, on-demand or episodic. We discussed doing prophylaxis, but then there was this opportunity to participate in a clinical trial with this drug called emicizumab. I’ll just give you a little bit of a background on what emicizumab is. It’s actually not factor, it’s what we call a nonfactor therapy. It’s a therapeutic monoclonal antibody called a bispecific monoclonal antibody. That means it binds to activated factor IX and factor X and mediates the activation of factor X. The role of factor VIII is to bind activated factor IX and X and bring them together, which activates factor X, and that goes on to activate the rest of the clotting cascade. Patients with hemophilia are missing factor VIII. This bispecific antibody takes on this role and will bridge the binding of factors IX and X together. Thus, it activates factor X, and it restores hemostasis.
Eric Mamos: Right. It’s like a bunch of dominos.
Doris V. Quon, MD: Exactly.
Eric Mamos: Factor VIII is one of the dominos that’s missing.
Doris V. Quon, MD: Right, and it’s a very important domino.
Eric Mamos: The new drug tricks the next 2 dominos, saying, “Hey, factor VIII already happened, keep doing your job.”
Doris V. Quon, MD: Right. That’s the mechanism of action. We asked you to participate in using this. This drug was used for both patients with inhibitors and without inhibitors in hemophilia A.
Eric Mamos: Correct.
Doris V. Quon, MD: What was your experience with emicizumab when I asked you to use it?
Eric Mamos: Oh, I thought the potential was amazing. The only thing I really say about it is that it has been life-changing. I’ve been on it for a year and a half or something like that now, right? I have not done a single factor VIII infusion in that time. This infusion is super convenient. My protocol is around 1 shot every 2 weeks, and it’s similar to a diabetic shot. It goes right in the fat, not in the vein, so it’s really easy to do. I don’t need to worry about missing veins, and it’s around 2 cubic cm. It’s very, very small. And then, all of a sudden, I’m good for the next few weeks. That’s just been a huge, huge life changer. When I would feel a little bit of pain when I was a kid, I would procrastinate and say, “Oh, it will go away,” but it never did. Now I say, “I have a little pain, it will go away,” and it does go away. I’m thinking, “Oh, this is new.” It has been a complete life changer and game changer, I think.
Doris V. Quon, MD: As the clinical trial draws to an end, what do you think? Would you consider continuing on this medication?
Eric Mamos: I definitely cannot consider going back, so yes.
Doris V. Quon, MD: Moving forward, you’re going to try to continue on this medication.
Eric Mamos: I don’t even know why I would ever go back.
Doris V. Quon, MD: The data on the study were published, and I don’t know if you actually have seen the data.
Eric Mamos: I have not.
Doris V. Quon, MD: I haven’t reviewed it with you. There were 3 arms to this study. One arm was continuing on-demand therapy using factor VIII as you needed; one arm was what you were on, which was giving yourself the emicizumab shot every other week; and the third arm was actually using shots once a week with emicizumab. They actually found that compared to on-demand treatment, there was a 96% decrease in the annualized bleed rates. They measured the number of bleeds you had per year, and they looked at the annualized bleed rate. In the bleed rate, there was a 96% reduction in the once-a-week arm and a 97% reduction in the every-2-week arm.
Eric Mamos: So, 2 weeks is more effective by a little?
Doris V. Quon, MD: That’s not statistically significant.
Eric Mamos: Right, right.
Doris V. Quon, MD: Let’s just say over 95%.
Eric Mamos: But as good. Wow.
Doris V. Quon, MD: It’s just as good. And so, there was another study that they called HAVEN 4—yours was HAVEN 3—and they actually looked at this drug being used once a month. That’s another consideration, and very similarly, the annualized bleed rates compared to on-demand therapy were much improved.