Thrombopoietin level predicts response to treatment with eltrombopag and romiplostim in immune thrombocytopenia.

Thrombopoietin receptor agonists (TPO-RAs) are used to treat immune thrombocytopenia (ITP), but predicting clinical response to TPO-RAs before initiation is not possible. To determine whether endogenous TPO levels predict treatment response to TPO-RAs we performed a retrospective analysis of ITP patients with known baseline TPO levels who received TPO-RAs. Data was collected for ITP patients with a baseline TPO level treated with eltrombopag or romiplostim. Multiple logistic regression was used to model the probability of 3 classes of treatment response (overall, moderate, and superior) based on TPO level; receiver operating characteristic (ROC) analysis was performed to identify optimal TPO thresholds for response; correlations between TPO level and various response characteristics were analyzed. A total of 67 patients (37 receiving eltrombopag and 46 receiving romiplostim) were included. Logistic regression models demonstrated a significant predictive relation between TPO level and probability of all classes of response; per 10 pg/mL TPO increase, 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 inversely correlated with all classes of response; for overall response, r = -0.719 (P < .001) for eltrombopag and r = -0.584 (P < .001) for romiplostim. ROC analysis identified TPO thresholds of ≤136 pg/mL (eltrombopag) and ≤209 pg/mL (romiplostim) as optimally discriminating between responders and nonresponders. Most non-responders had high TPO levels but did respond after addition of low-dose prednisone. In conclusion, TPO levels predict response to eltrombopag and romiplostim in ITP patients, with lower levels predicting improved probability and magnitude of response.

Al-Samkari H ，Kuter DJ 《-》

The use of thrombopoietin-receptor agonists (TPO-RAs) in immune thrombocytopenia (ITP): a "real life" retrospective multicenter experience of the Rete Ematologica Pugliese (REP).

Mazza P ，Minoia C ，Melpignano A ，Polimeno G ，Cascavilla N ，Di Renzo N ，Specchia G ... -  《-》

Thrombopoietin Receptor Agonists: Eltrombopag and Romiplostim for the Treatment of Chronic Immune Thrombocytopenia Purpura.

Atkinson K 《-》

Thrombopoietin receptor agonists in refractory immune thrombocytopenia: differential responses to eltrombopag and romiplostim: a case report and possible explanations.

Although new thrombopoietin (TPO) receptor agonist drugs, such as romiplostim and eltrombopag, are highly effective and well tolerated for patients with immune thrombocytopenia (ITP) refractory to first-line treatments such as prednisolone, the cross-resistance of these two TPO receptor agonists is still unknown. An 84-year-old Japanese female patient with steroid-refractory ITP received eltrombopag with a gradually increasing dose schedule from 12.5 to 25 mg/day, 37.5 mg/day and finally 50 mg/day. As no increase in platelet count was observed even at the maximum dose of 50 mg/day, and eltrombopag-related grade 3 elevation of aspartate aminotransferase was observed, another TPO receptor agonist, romiplostim, was administered at 1 μg/kg/week subcutaneously. A rapid increase in platelet count was observed 1 week after the first injection. The dose of romiplostim was escalated to 4 μg/kg according to the platelet count and a complete response was achieved 7 weeks after the first injection without any adverse events. The successful treatment of ITP refractory to eltrombopag with romiplostim strongly suggests that the absence of cross-resistance between these two approved TPO receptor agonists and possible differences in mechanism of action. Further study of the mechanisms of action of TPO receptor agonists is called for along with further exploration of the potential of romiplostim in refractory ITP.

Aoki T ，Harada Y ，Matsubara E ，Suzuki T ，Oyama T ，Kasai M ，Uchida T ，Ogura M ... -  《-》

Treatment patterns and clinical outcomes in patients with chronic immune thrombocytopenia (ITP) switched to eltrombopag or romiplostim.

Kuter DJ ，Macahilig C ，Grotzinger KM ，Poston SA ，Wang PF ，Dawson KL ，Ward M ... -  《-》