FDA Approves Romiplostim for Earlier Use in Adults With ITP

The FDA has approved a supplemental biologics license application (sBLA) for an updated indication expanding the use of romiplostim (Nplate) in the treatment of adult patients with immune thrombocytopenia (ITP) to include newly diagnosed patients and patients with persistent ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy.¹

The sBLA sought to add additional data to the prescribing information for romiplostim on sustained platelet responses. Additional data came from a phase II trial of adults with ITP who had an insufficient response to their first-line therapy, showing a treatment-free remission lasting ≥6 months in 32% of patients. 

"These new data are the first of their kind to prospectively examine treatment-free remission as an outcome for patients with ITP. Thirty-two percent of patients who received Nplate soon after an insufficient response to the first course of steroids maintained platelet response for at least 6 months without Nplate or any other ITP therapy," David M. Reese, MD, executive vice president of Research and Development at Amgen, the company developing romiplostim, said in a press release. "This approval will provide patients the opportunity to receive Nplate earlier in the course of their disease, potentially reducing their need for prolonged steroid use. We are excited to make Nplate available to more patients with this rare blood disorder."

The open-label, single-arm trial enrolled 75 adult patients who had been diagnosed with ITP within 6 months of enrollment in the study and had received 1 prior treatment regimen for ITP. Eligible patients also had to have a platelet count of ≤30 × 10⁹/l at some time during the 4‐week screening period.²

Patients received romiplostim for 12 months starting at 1 µg/kg. Those who had platelet counts ≥50 × 10⁹/l after 12 months were able to taper the dose over 19 weeks as long as platelet counts of ≥50 × 10⁹/l were maintained.

The primary endpoint of the trial was the cumulative number of months of platelet response (platelet counts ≥50 × 10⁹/l) in the treatment period, and secondary endpoints included ITP remission, incidence of splenectomy, and adverse events (AEs).

The median age of the patients was 39 (range, 29-57) and 59% were women. Patients had been diagnosed a median of 2.2 months (range, 0.9-4.3) months before enrollment in the trial and the median platelet count at screening was 20.0 × 10⁹/l. Most patients (57%) had received only 1 prior ITP treatment and 43% had received ≥2 treatments. 

The median cumulative number of months of a platelet response was 11 (range, 8-12; 95% CI, 10-11) and the median time to a platelet response was 2.1 weeks (range, 1.1-3.0). Ninety-three percent of patients achieved a platelet response during the treatment period.

Twenty-four patients achieved remission for ≥6 months without romiplostim or any other ITP treatment. The median time to the onset of ITP remission was 27 weeks (range, 6-57). 

Frequent AEs observed included headache (16%), arthralgia (15%), nasopharyngitis (12%), and hematoma (11%). Bleeding events were reported in 31% of patients, only 1 case of which was considered treatment-related, and none were considered serious. Thrombocytosis occurred in 2% of adults who had ITP for ≤12 months.

Adverse events of bronchitis, sinusitis, vomiting, arthralgia, myalgia, headache, dizziness, diarrhea, upper respiratory tract infection, cough, nausea and oropharyngeal pain occurred somewhat more often in patients with ITP for ≤12 months who were treated with romiplostim compared with standard of care or placebo.¹

Serious AEs were reported in 19% of patients and were considered treatment-related in 4%; these events were gastritis, increased transaminases, and reversible ischemic neurological deficit in 1 patient each. AEs led to treatment discontinuation in 5% of patients.

In December of last year, theFDA approved another sBLA for romiplostim for the treatment of pediatric patientsaged ≥1 year who have had ITP for at least 6 months and had an insufficient response to corticosteroids, immunoglobulins, or splenectomy.

References:

1. Nplate® (romiplostim) Now Approved For Earlier Use In Adults With Immune Thrombocytopenia [press release]. Thousand Oaks, CA: Amgen; October 18, 2019. https://prn.to/33GWGiv. Accessed October 18, 2019.
2. Newland A, Godeau B, Priego V, et al. Remission and platelet responses with romiplostim in primary immune thrombocytopenia: final results from a phase 2 study.Br J Haematol.2016;172(:262-273. doi: 10.1111/bjh.13827.