Photo by Bill Branson
The thrombopoietin receptor agonist romiplostim can produce durable platelet responses in children with symptomatic chronic immune thrombocytopenia (ITP), according to a phase 3 study.
Fifty-two percent of patients who received romiplostim achieved a durable platelet response, compared to 10% of placebo-treated patients.
Investigators said these results suggest romiplostim may be a treatment option for this patient population.
“The results of this study suggest that romiplostim could reduce the frequency and severity of bleeding events for children suffering from symptomatic ITP, thus providing them with another potential treatment option,” said Michael D. Tarantino, MD, of the University of Illinois College of Medicine-Peoria.
Dr Tarantino and his colleagues reported the results in The Lancet. The study was supported by Amgen, which markets romiplostim (Nplate) as a treatment for adults with chronic ITP.
This double-blind study included 62 children (ages 6 to 14) who had ITP for more than 6 months and were randomized to weekly romiplostim (n=42) or placebo (n=20) for 24 weeks. Baseline characteristics were well-balanced between the treatment arms.
The median time since ITP diagnosis was about 2 years for both arms, and the median age at diagnosis was about 7. The median baseline platelet counts were 17.8 x 109/L in the romiplostim arm and 17.7 x 109/L in the placebo arm.
Durable platelet response, the primary endpoint of the study, was defined as achieving weekly platelet responses without rescue medication in at least 6 of the final 8 weeks of the study.
The rates of durable platelet response were 52% (22/42) in the romiplostim arm and 10% (2/20) in the placebo arm (P=0.002, odds ratio 9.1, 95% CI: 1.9, 43.2).
The rates of overall platelet response were 71% (30/42) in the romiplostim arm and 20% in the placebo arm (P=0.0002, odds ratio 9.0, 95% CI: 2.5, 32.3), and the rates of any platelet response were 81% (34/42) and 55% (11/20), respectively (P=0.0313).
The most frequently reported adverse events (AEs) observed in patients receiving romiplostim were contusion (50%), epistaxis (48%), headache (43%), and upper respiratory tract infection (38%).
Oropharyngeal pain occurred more frequently with romiplostim than placebo—26.2% (11/42) and 5.3% (1/19), respectively.
In the 11 romiplostim-treated patients with oropharyngeal pain, streptococcal pharyngitis (n=2), allergic rhinitis (n=2), gastroesophageal reflux (n=1), and serum sickness from IVIg (n=1) were also reported. No oropharyngeal pain AEs were serious or considered treatment-related.
Serious AEs occurred in 23.8% of romiplostim-treated patients and 5.3% of placebo-treated patients.
Serious AEs in the romiplostim arm included epistaxis (n=2), contusion (n=2), headache (n=2), bronchiolitis (n=1), nausea (n=1), petechiae (n=1), epilepsy (n=1), fever (n=1), thrombocytosis (n=1), urinary tract infection (n=1), and vomiting (n=1).
One subject with treatment-related serious AEs experienced headache and thrombocytosis, which did not recur when romiplostim was restarted.
There were no thrombotic events, none of the patients withdrew due to AEs, and none died.
“These data are important in understanding how Nplate may play a role in helping children manage this disease,” said Sean E. Harper, MD, executive vice president of research and development at Amgen.
“We will work with regulatory authorities towards an approval for Nplate for pediatric patients.”
