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Amgen Presents Data From First Nplate(R) Study in Children With Chronic ITPUpdated Five-Year Long-Term Data in Adults with Chronic ITP Also Presented at ASH Annual Meeting
Results from Phase 1/2 Study in Children (Abstract #680)
ITP in children most commonly presents as an acute illness; however, 20-30 percent of these cases will persist as chronic ITP (duration over six months). Results of the study showed that treatment with Nplate appeared to be generally well-tolerated compared to placebo in children (aged 12 months to less than 18 years old) with chronic ITP (treatment related adverse events = 18 percent vs. 20 percent, respectively).
"Currently, most drug treatment options for children with chronic ITP involve immunosuppression," said Dr.
Safety results of the study showed that adverse event rates were similar between those patients treated with Nplate or placebo with most adverse events being mild to moderate in severity. Most frequent adverse events in patients taking Nplate or placebo were headache (35 percent vs. 40 percent, respectively), epistaxis (35 percent vs. 20 percent, respectively), cough (12 percent vs. 40 percent, respectively) and vomiting (12 percent vs. 40 percent, respectively).
Efficacy results showed that Nplate was effective in treating thrombocytopenia compared to placebo, with 88 percent of the 17 patients receiving Nplate achieving both efficacy endpoints during treatment (number of patients achieving a platelet count of over 50,000 platelets per microliter for two consecutive weeks during the treatment period and/or achieving an increase in the platelet count of 20,000 platelets per microliter above baseline for two consecutive weeks). Other observations included a decrease in rescue medication use, and numerically lower duration-adjusted bleeding adverse event rates with Nplate treatment as compared with placebo. None of the placebo-treated patients (n=5) achieved either efficacy endpoints.
This Phase 1/2, 12-week treatment period evaluated the safety and efficacy of Nplate in the treatment of thrombocytopenia in children with chronic ITP (n=22). The study involved children with ITP aged 12 months to less than 18 years old with persistent severe thrombocytopenia for at least six months. The median age of study participants was 9.5 years. Nplate was administered subcutaneously at 1 mcg/kg once-weekly and doses were adjusted to a maximum dose of 10 mcg/kg weekly.
Results from Ongoing, Long-Term Extension Efficacy and Safety Study (Abstract #681)
Results from an ongoing, long-term extension study in adults that were also presented at the meeting showed that Nplate maintained platelet counts within a range of 50,000 to 200,000 platelets per microliter in the majority of adult patients with chronic ITP with minimal dose adjustments for up to nearly five years. Over the course of the study, a platelet count of greater than or equal to 50,000 platelets per microliter was achieved by 94 percent of 291 patients receiving Nplate, and the median platelet count remained greater than or equal to 50,000 platelets per microliter for the duration of the study after Week 1.
Patients were treated for a median of 48 weeks with a maximum duration of 244 weeks (n=4) and 33 percent of patients had previously undergone splenectomy.
"This updated five-year data represents the longest adult chronic ITP study ever conducted and the findings add to the data available on the long-term efficacy and safety of Nplate," said
In addition, results showed that treatment with Nplate was generally well-tolerated and adverse event rates did not increase with longer duration of treatment. Of the 37 patients receiving concurrent ITP treatment (i.e., corticosteroids, IVIG, Win-Rho, Anti-D therapy), 78 percent were able to discontinue or reduce their dose of Nplate by more than 25 percent. Home administration of Nplate was achieved by 75 percent of patients.
This is an ongoing, open-label, long-term efficacy and safety study of Nplate for the treatment of patients with chronic ITP. Nplate was administered once weekly by subcutaneous injection, with dose adjustments to maintain platelet counts in the target range (50,000 to 200,000 platelet count per microliter). The primary study objective was to determine long-term safety of Nplate. Secondary study objectives were to evaluate long-term platelet responses and the use of concurrent ITP therapies.
About Adult ITP
In patients with ITP, platelets - blood elements needed to prevent bleeding - are destroyed by the patient's own immune system. Low platelet counts leave adult ITP patients open to sudden serious bleeding events. The risk for serious bleeding events increases when platelet counts drop to less than 30,000 platelets per microliter; normal counts range from 150,000 to 400,000 platelets per microliter. ITP has historically been considered a disease of platelet destruction although recent data suggest that the body's natural platelet production processes in ITP are unable to compensate for low levels of platelets in the blood. Increasing the rate of platelet production may address low platelet levels associated with ITP.
Other available treatments (i.e., corticosteroids, immunoglobulins) have limited application due to poor tolerability or transient effects. Surgical therapy (removal of the spleen) is also available to adult patients with chronic ITP, but does not work in all cases. Currently, there are approximately 90,000 adult chronic ITP patients in
Nplate is only indicated to treat adult chronic ITP. Nplate is currently under investigation for children ages 12 months to 18 years old with persistent severe thrombocytopenia.
Nplate is the first platelet producer approved in the
Nplate is the first treatment specifically developed for chronic ITP. It is also being investigated for potential use in pediatric ITP, myelodysplastic syndromes (MDS) and chemotherapy-induced thrombocytopenia (CIT).
In the U.S., Nplate is indicated for the treatment of thrombocytopenia in patients with chronic immune ITP who have had an insufficient response to corticosteroids, immunoglobulins or splenectomy. Nplate should be used only in patients with ITP whose degree of thrombocytopenia and clinical condition increases the risk for bleeding. Nplate should not be used in an attempt to normalize platelet counts.
In the EU, Nplate is indicated for the treatment of splenectomized adult chronic ITP patients who are refractory to other treatments (e.g. corticosteroids, immunoglobulins). Nplate may be considered as a second-line treatment for adult non-splenectomized ITP patients for whom surgery is contra-indicated.
Nplate was named as a recipient of the U.S. Prix Galien( )2009 "Best Biotechnology Product" award and also received the 2009 Scrip Awards for "Best New Drug."
Important U.S. Nplate Safety Information
Serious adverse reactions associated with Nplate in clinical studies were bone marrow reticulin deposition and worsening thrombocytopenia after Nplate discontinuation. Additional risks include bone marrow fibrosis, thrombotic/thromboembolic complications, lack or loss of response to Nplate, and hematological malignancies and progression of malignancy in patients with a pre-existing hematological malignancy or MDS. Nplate is not indicated for the treatment of thrombocytopenia due to MDS or any cause of thrombocytopenia other than chronic ITP.
Nplate is available only through a restricted distribution program called Nplate® NEXUS (Network of Experts Understanding and Supporting Nplate and Patients) Program.
In the placebo-controlled studies, headache was the most commonly reported adverse drug reaction.
Important EU Nplate Safety Information
The most common side effects are headache, fatigue, arthralgia, myalgia, injection site bruising, injection site pain, peripheral edema, dizziness, muscle spasms, nausea, contusion, diarrhea, bone marrow disorder, influenza like illness, insomnia and pruritus.
Reoccurrence of thrombocytopenia and bleeding after cessation of treatment and increased bone marrow reticulin have been associated with Nplate treatment in the clinical trials. Thrombotic/thromboembolic complications, progression of existing hematopoietic malignancies or MDS, and effects on red and white blood cells are all potential risks associated with Nplate treatment. As with all therapeutic proteins, patients may develop antibodies to the therapeutic protein.
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