Use of Romiplostim in Chronic Immune Thrombocytopenia


Considerations for the uptake and use of romiplostim, an injectable thrombopoietin receptor agonist, in immune thrombocytopenia.


Morey Blinder, MD:Howard, do you want to just comment a little bit about romiplostim? You have broad clinical experience such as clinical trials.

Howard Liebman, MD: The funny thing is that when we did the clinical trial, the patients self-injected themselves at home. But for reasons that were not known, and probably for the same reason that they set up a REMS [Risk Evaluation and Mitigation Strategies] program, if you remember, for that drug, they were just insecure. The FDA has been less insecure about ITP drugs nowadays after requiring all of us to fill out REMS for 5 years. It can be a very potent agent, there's no doubt about it, and the trouble now is that it has still not been approved for home injection, so patients have to come in. There are ups and downs on it, and if you look at measuring platelet counts when patients come in, you see such variation in the platelet responses. Some patients just do very well on it and don't mind coming in. Basically, a lot of it is truly defined, as it is, even with the 2 oral agents, by what insurance coverage is and Medicare coverage is, so that they're able to actually come in and get the drug regularly. And particularly, many patients who live in the nearby region.

Howard Liebman, MD: Patients do well with long-term experience. I think if we were allowed to do home injection, and patients were taught home injection as they were with the clinical trial, I think it would come back into favor more than it is now. I think that's the fall of the FDA. But Dave Kuter, MD, [at the Cancer Center, Mass General Research Institute, Boston, MA] found that some insurance companies will allow home injection via nurses, and if that can be set up, I think that's a worthwhile approach. Patients are very happy just getting a once-a-week injection and feeling safe with their platelet counts.

Morey Blinder, MD:Yeah, I'm perplexed about that too, that it never was approved for home use. Do you think it has to do with the idea that these vials are fixed-dose, and you have to draw up, very carefully, the exact milligram or microgram per kilogram dose and then inject it, and if you're off, you could really screw things up? That's my best answer to that reasoning.

Howard Liebman, MD: Yes, but insulin, historically, has been that way for years, and it didn't stop people from doing home injections with insulin for decades.

Morey Blinder, MD:Fair point.

Howard Liebman, MD: So, I think that's a problem. I agree that I think the FDA is looking for everything that can go wrong, but in reality, in most of the patients, particularly the younger patients, can have a platelet count go to 1,000,000 and they're not getting strokes. So, obviously, I worry more about it in older patients. Most patients, if the platelet count drops down to 20,000 because they've underdosed, are not going to start bleeding again.

Cindy Neunert, MD: I don't know how I've been so fortunate, but we've had a huge amount of success, and I probably should give the credit to the nurse practitioner that works with my patients for getting pediatric patients home use.I can tell you just from that clinical experience that there's very little error that has occurred, and the majority of our patients are now on home use. I thought most families would prefer not to go with something that was injectable. But when you start to talk with families not having to get their child to take a pill every day, or if it's an adolescent not having to worry about taking a pill every day, I've actually had a lot of people favor romiplostim—although only once we know that we can get it for home use and the inconvenience of coming to the clinic every week is gone. So that definitely influences preference, and it is a shame for the patients that we can't make them all equal in delivery. But for those of my pediatric patients that have been able to get home use, it's been quite effective. For the patients, it's quite nice for them to not have to think about something daily. It's a once-a-week, and then they really don't have to think about it, and they still know what to call us for.

We teach them how to do it in the clinic. We show them how to draw it up and reconstitute it, and it really goes quite well. But we do that for a lot of our therapies. We have to teach families how to do Lovenox [enoxaparin] and things like that, so it's not that much different. To your point, I don't really know where the heightened alarm came from. I will also say in pediatrics, a lot of us have sort of foregone the starting at 1 mcg [microgram] and inching our way up by 1 MCG and recognizing that overshooting rarely happens. It's a lot easier to either start at a slightly higher dose or take slightly higher increments. I also think that dosing is very conservative dosing, again based on what was needed for that FDA approval in the clinical trials, and probably doesn't mirror what's happening in clinical practice or the best way to actually titrate up the drug or get to full effect as quickly as we could.

Howard Liebman, MD: I think the point is that in the adults, it's somewhat different. In the original trial data, it shows that in the group that had their spleens in, the average dosing was 3 mcgs per kilogram to maintain the platelet counts above 50,000. A little higher for the post-splenectomy were more effective, was 4 mcgs. And Dave Kuter, in the second publication about sparing splenectomy, used the 3 mcgs. So, we start at the 3 mcgs on patients who are going to be on the drug long-term, and most of them don't really require much more. I think it's pretty effective in terms of an agent.

Morey Blinder, MD:I think those are good points. I think all this speaks to the nuances of using these therapies where they may seem straightforward; then you get some experience, and you realize there are a lot of variabilities—a lot of ways to skin a cat.

Transcript edited for clarity.

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