Romiplostim in splenectomized patients

There is an increased risk of thrombosis in splenectomized patients as well as in patients treated with romiplostim (Nplate).
This study shows that there is not an increase in risk of romiplostim in splenectomized patients.

Note that there seems to be a new trend away from the term "ITP" toward "primary immune thrombocytopenia".
A search on "ITP" would miss this article entirely.

www.haematologica.org/content/early/2017/04/14/haematol.2016.161968
Safety And Efficacy Of Romiplostim In Splenectomized And Nonsplenectomized Patients With Primary Immune Thrombocytopenia
Douglas B. Cines, Jeffrey Wasser, Francesco Rodeghiero, Beng H. Chong, Michael Steurer, Drew Provan, Roger Lyons, Jaime Garcia-Chavez, Nancy Carpenter, Xuena Wang, Melissa Eisen
Haematologica April 2017 : haematol.2016.161968; Doi:10.3324/haematol.2016.161968
Abstract
Primary immune thrombocytopenia is an autoimmune disorder characterized by increased platelet destruction and insufficient platelet production without another identified underlying disorder. Splenectomy may alter responsiveness to treatment and/or increase the risk of thrombosis, infection, and pulmonary hypertension. This analysis evaluated the safety and efficacy of the thrombopoietin receptor agonist romiplostim in splenectomized and nonsplenectomized adults with primary immune thrombocytopenia. Data were pooled across 13 completed clinical studies in adults with immune thrombocytopenia from 2002-2014. Adverse event rates were adjusted for time of exposure. Results were considered different when 95% confidence intervals were nonoverlapping. Safety was analyzed for 1111 patients (395 splenectomized; 716 nonsplenectomized) who received romiplostim or control (placebo or standard of care). At baseline, splenectomized patients had a longer median duration of immune thrombocytopenia and a lower median platelet count, as well as a higher proportion with >3 prior immune thrombocytopenia treatments versus nonsplenectomized patients. In each treatment group, splenectomized patients used rescue medications more often than nonsplenectomized patients. Platelet response rates (≥50x109/L) for romiplostim were 82% (310/376) for splenectomized and 91% (592/648) for nonsplenectomized patients (P<0.001 by Cochran-Mantel-Haenszel test). Platelet responses were stable over time in both subgroups. Exposure-adjusted adverse event rates were higher for control versus romiplostim for both splenectomized (1857 versus 1226 per 100 patient-years) and nonsplenectomized patients (1052 versus 852 per 100 patient-years). In conclusion, responses to romiplostim were seen in both splenectomized and nonsplenectomized patients, and romiplostim was not associated with an increase in the risk of adverse events in splenectomized patients.

PIT? Nah, I don't like that.
I'm having a hard time believing those study results. I'd like to see more data backing that up.

"Exposure-adjusted adverse event rates were higher for control versus romiplostim for both splenectomized (1857 versus 1226 per 100 patient-years) and nonsplenectomized patients (1052 versus 852 per 100 patient-years)"

Sandi, you have good instincts! What they are actually saying is that it is safer to take Nplate than to take placebo, regardless of whether the patient is splenectomized. They are not saying that splenectomized patients are at no greater risk than non-splenectomized patients.

The same data also show that splenectomy patients are at a higher risk than non-splenectomized patients.
My version:
Exposure-adjusted adverse event rates were higher for splenectomized patients versus non-splenectomized patients for both Nplate patients (1226 versus 852 per 100 patient-years) and non-Nplate patients (1857 versus 1052 per 100 patient-years).

Same data, different message.

PIT?
ITP is the pits, that's for sure!

That's a long study. Hot off the press.
"
In each treatment group, splenectomized patients used rescue medications more often than nonsplenectomized patients
"
I wonder if that (rescue treatments) is the sole reason why control adverse events were greater than the NPlate adverse events. Would have to think rescue would be a very rare event when taking NPlate. Not so much in the control groups.

I like 'Thrombocytopenia Roller Coaster' or 'TRC' better

Just when I was finally learning to not call it Idiopathic Thrombocytopenia Purpura, which is what I learned to call it as a kid. Now I get to call it PIT, ha! It is definitely the pits. Good to see you keeping us up to date with the new articles Rob, thanks! I hope all is going well with your wife.

Mom, when was the last time you had a 'rescue treatment' ? From interpreting the data in this study it appears the real clotting danger is from rescue treatments/events. And that taking a TPO-A causes fewer rescue treatments and thus fewer clotting events.