Morey Blinder, MD: Let's just briefly talk about the definitions here of chronic and persistent disease. Danny, do you have any comments on defining this and how it might influence your therapy?

Daniel Landau, MD: I think the definition that a lot of us use is ITP that's persistent for 3 or more months and have either a refractory nature to corticosteroids or a very transient response to corticosteroids. That's probably the definition most of us are using nowadays.

Morey Blinder, MD: I think that's fair. Cindy, do you want to say anything more about that from the guidelines about chronic and persistent disease or can we move off that topic?

Cindy Neunert, MD: I think we can move off that. I think we can all agree it's rather arbitrary, but they're just so that we can kind of talk similar language when we're talking about patients and for clinical trials.

Howard Liebman, MD: If I can make a comment about that. That was initially developed by the International Working Group. It was a meeting that Francesco Rodeghiero [Scientific Director, Fondazione Progetto Ematologia, Italy] put together in Vicenza, Italy. I was invited, but I was at another meeting for thrombosis in another part of Italy at the time. The interesting aspect of it is that it was based upon the impression from literature that there were still individuals who were in that early phase who could go into remission. They were what I would call the pediatric adults. They're the 18- to 25-year-olds, particularly women, who come in with thrombocytopenia whom you treat who actually at 1 year are still in remission. That was about 20% to 30%, the estimates were, so they saw most of those transitions to coming off treatment and having a normal platelet count within that first 3 months. Yet persistent was that 3 months to a year, and they still saw individuals who'd obtained remission in that time. So that's what I learned when I learned about ITP—that it was 6 months and it was chronic. They moved it out to a year and that's why they wanted to move out the splenectomy data. The fact that they were doing splenectomies on individuals at 6 months probably contaminated the outcome splenectomy data because a number of those individuals would've had a spontaneous remission anyway. I think that's part of the reason why we use it. I think it's a valid separation based on the literature. It gives you some options about how you're going to treat them after the initial treatment with steroids and IVIG that might be less aggressive for a period of time.

Cindy Neunert, MD: I think to your point, that is why the guidelines have really recommended delaying splenectomy. For the other therapies, in my mind, what's often less important, I think it all factors in and we're going to start talking about second-line therapies and sort of who and when, but I think that what's more important is actually the refractory nature of the ITP, and the other therapies a patient has already had, and sometimes there's a hesitancy to move towards second-line therapies until somebody is persistent or is chronic. If you need to advance to second-line therapy, it doesn't mean that somebody has to hit a definitive time point in their ITP. A lot of these are getting moved up earlier in the course of the disease for refractory patients. It's more the refractory than the duration that we all worry about.

Howard Liebman, MD: I would agree. I think a lot of that comes into play and why the changes were against Adrian Newland [professor of hematology, Barts Health National Health Service Trust, London, England], in his classic paper in British hematology. Now I call it a classic because it really leads us—when we talk about second-line treatment, to an approach that I think is reasonable and promising.

Transcript edited for clarity.