Researchers have reported a high rate of sustained response off treatment (SROT) after thrombopoietin receptor agonist (TPO-RA) discontinuation among patients with persistent or chronic immune thrombocytopenia (ITP) who achieved a stable complete response (CR) on TPO-RAs, according to a study published in Blood.
The investigators conducted a prospective, multicenter, interventional study of adults with persistent or chronic primary ITP and CR on TPO-RAs (ClinicalTrials.gov ID: NCT03119974).
Upon inclusion, patients underwent dose reduction and weaning of eltrombopag or romiplostim according to a standardized protocol for each TPO-RA. Eltrombopag was tapered by 25 mg every 2 weeks or stopped at week 0 for patients already at 25 mg per day. Romiplostim was tapered by 1 μg/kg every week until discontinuation. Tapering continued as long as the patient’s platelet count remained >30 × 109/L.
The aim was to stop the TPO-RA by week 10. In cases of relapse (bleeding event and/or platelet count decrease <30 × 109/L), the investigators increased the dosage of TPO-RA, rechallenged the patient with a TPO-RA, or initiated a new treatment line as needed.
The primary endpoint was the proportion of patients who achieved SROT (platelet count >30 × 109/L and no bleeding) at week 24 with no other ITP-specific medications. Key secondary endpoints included the proportion of sustained CR off-treatment (SCROT, platelet count >100 × 109/L and no bleeding), SROT at week 52, bleeding events, and response to a new course of TPO-RAs in the case of relapse.
A total of 48 patients (median age, 58.5 years; interquartile range [IQR], 41-73.5; 60.5% female) were included in the study. At TPO-RA initiation, 63% of patients had chronic ITP. The median maximal platelet count achieved on TPO-RA was 291 × 109/L (range, 215 × 109/L to 408 × 109/L). At inclusion, most patients (83%) were on eltrombopag (17% on romiplostim). The median duration of TPO-RA exposure was 1.6 years (IQR, 1.0-3.8).
In the intention-to-treat analysis, 56.2% of patients (95% CI, 41.2-70.5) achieved SROT and 31.3% of patients (95% CI, 18.9-44.5) achieved SCROT at week 24. Similar results were observed at week 52 (SROT, 52.1%; 95% CI, 37.2-66.7; SCROT, 29.2%; 95% CI, 17.2-42.3).
Among patients who relapsed by week 24 (n=21) and week 52 (n=23), a bleeding event occurred in 57.1% and 60.9% of the patients, respectively. No severe bleeding episodes occurred. Among patients who relapsed before week 24 and were rechallenged with the same TPO-RA, 91.7% achieved CR.
“In conclusion, our study strongly supports a strategy of progressive tapering and weaning of TPO-RAs for adults with persistent or chronic ITP who achieve a stable CR on TPO-Ras,” the authors wrote in their report.
Limitations of the study included potential selection bias, possible instances of spontaneous remission, and use of eltrombopag in most patients.
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of authors’ disclosures.
Guillet S, Crickx E, Azzaoui I, et al. Prolonged response after TPO-RA discontinuation in primary ITP: results of a prospective multicenter study. Blood. 2023;141(23):2867-2877. doi:10.1182/blood.2022018665