A patient’s baseline level of thrombopoietin (TPO) may help to predict whether he or she will respond to treatment with eltrombopag or romiplostim for immune thrombocytopenia (ITP), according to a retrospective study.1
The analysis found that a TPO threshold of 136 pg/mL or 209 pg/mL or less predicted response to eltrombopag and romiplostim, respectively.
There are currently no accurate biomarkers that can predict clinical response to thrombopoietin receptor agonists for patients with ITP. Responses to these medications vary greatly, and patients who do not respond may be exposed to prolonged periods of thrombocytopenia and “considerable financial investment” for little to no benefit.
Researchers hypothesized that baseline TPO levels might predict response to ITP receptor agonists. They conducted a retrospective study including 67 patients with ITP; 37 on eltrombopag and 46 on romiplostim (16 patients had discrete treatment episodes with each drug).
The analysis revealed that with each 10 pg/mL increase in TPO, the odds ratio for overall response to eltrombopag was 0.524 (95% CI, 0.327-0.837) and romiplostim was 0.905 (95% CI, 0.844-0.970). TPO level was significantly inversely related to overall response, moderate response, and superior response (P < .01).
There were 11 patients who did not achieve overall response when treated with the maximum doses of eltrombopag or romiplostim who had low-dose prednisone added to their regimens. With the addition of prednisone, 9 of these patients achieved an overall response.
The researchers noted several limitations to the study, including its retrospective nature, and that confirmation of these findings with a prospective study “would be helpful.”
- Al-Samkari H, Kuter DJ. Thrombopoietin level predicts response to treatment with eltrombopag and romiplostim in immune thrombocytopenia [published online September 6, 2018]. Am J Hematol. doi:10.1002/ajh.25275.