Remission and platelet responses with romiplostim in primary immune thrombocytopenia: final results from a phase 2 study

Abstract

In anecdotal reports, some patients with immune thrombocytopenia (ITP) maintained platelet counts after discontinuing romiplostim. Here, we examined rates of platelet response (≥50 × 10(9) /l), remission, splenectomy and adverse events in patients with primary ITP duration ≤6 months who were treated with romiplostim for ≤12 months. The starting dose of romiplostim was 1 μg/kg; concomitant and rescue treatments were permitted to maintain platelet counts. Patients with platelet counts ≥50 × 10(9) /l at the end of 12 months entered a dose taper in which the romiplostim dose was decreased as long as platelet counts were maintained. Remission (platelet count ≥50 × 10(9) /l for 24 consecutive weeks with no ITP treatments) was evaluated in patients once romiplostim was discontinued. Over the 12 months, a high response rate (>90%) was observed. Platelet response occurred quickly (median, ~2 weeks) and was observed for a cumulative median of 11 months. Remission was observed in 24 patients (32%); there were no significantly predictors of remission. Most (20/24) patients had remission start before the forced taper. No new safety signals were identified. Thus, in patients with early-stage ITP, romiplostim was well tolerated and induced rapid responses, with remission occurring in approximately one-third of patients (NCT01143038, Amgen 20080435).

Remissions after long-term use of romiplostim for immune thrombocytopenia

“…Our data are similar to findings from a recent study of 75 patients with newly diagnosed ITP treated with romiplostim, where 32% of patients achieved a remission (defined as a platelet count >50x10 9 /L for 24 consecutive weeks with no ITP treatments). 15 In these studies, some patients experienced remission after very brief exposure to TPO receptor agonist, in some cases less than one month. Spontaneous remissions occur commonly in ITP patients, and their association with brief exposure to TPO receptor agonists is unclear, and may simply be a coincidence.…”

Clinical updates in adult immune thrombocytopenia

“…The first study was a 12-month study of romiplostim in 75 patients with ITP for ,6 months where the romiplostim was tapered if the platelet count was $50 3 10 9 /L after the 12 months. 62 In this study, 32% of patients met the primary endpoint: platelet count $50 3 10 9 /L off therapy for 24 consecutive weeks after CMV, cytomegalovirus; HCV, hepatitis C virus; PCR, polymerase chain reaction; Rh, rhesus. *Quantitative immunoglobulin level measurement should be considered in children with ITP and is recommended in those children with persistent or chronic ITP as part of reassessment evaluation.…”

“…BLOOD 62 A second study looked at the combination of HDD 3 4 days followed by eltrombopag 50 mg/d for days 5 to 32. There were 12 adults in this study, and 9/12 patients (75%) had a platelet count $30 3 10 9 /L at 6 months and 8/12 (67%) at 12 months.…”

Splenectomy for immune thrombocytopenia: down but not out

“…on May 9, 2018. by guest www.bloodjournal.org From able to discontinue these agents and maintain stable platelet counts. 88,89 Similar to rituximab, some of these remissions may reflect the natural history of ITP.…”