The MDS Beacon™

Nplate (romiplostim) may be effective in the treatment of thrombocytopenia in myelodysplastic syndromes (MDS) patients according to a recent study, and may prove to be an alternative treatment to platelet transfusions for MDS patients with thrombocytopenia.

Thrombocytopenia (low platelet levels) can be an unfavorable prognostic factor for MDS survival. Increased thrombocytopenia is often linked to a shorter time to AML progression. Platelet transfusions are currently the only available treatment option for thrombocytopenia. Transfusions carry a set of risks including alloimmunization, allergic reaction, infection, and lung injury. Alloimmunization is a type of immunity that often makes platelet transfusions ineffective.

Nplate is a protein consisting of a peptide and an antibody (peptibody) that increases platelet production. The drug has shown to be effective in clinical trials in increasing platelet production in healthy individuals and patients with chronic immune thrombocytopenia.

Researchers studied the efficacy and safety of Nplate for treating thrombocytopenia in low- and intermediate-1 risk MDS patients.

The study included 44 patients, all of whom completed at least four weeks of treatment. Patients were divided into four groups that received 300, 700, 1,000, and 1,500 µg Nplate respectively, administered subcutaneously once a week for three weeks, with follow-up assessment during the fourth week. Patients who completed the four-week treatment could continue taking Nplate during an extension phase lasting up to one year.

All 44 patients completed the four-week treatment phase. Researchers found that patients in all four groups experienced an increase in platelet counts during the treatment phase. Twenty patients (45 percent) achieved a complete or major platelet response. The share of patients who achieved a complete or major platelet response was similar across the different treatment groups.

Patients who entered the extension phase were also evaluated for response duration. Of the 44 patients treated, 41 entered the extension phase. A durable platelet response was achieved by 46 percent of the patients. The median treatment duration for the patients who achieved a durable response was 37 weeks.

Nearly all patients (98 percent) experienced side effects, with the most common being fatigue, diarrhea, and headache. Severe side effects were experienced by 39 percent of patients, and one patient withdrew from the study as a result of adverse side effects.

Side effects in 39 percent of patients were attributed to Nplate, and 11 percent experienced severe Nplate-related side effects. All patients who experienced severe side effects received the highest Nplate dose of 1,500 µg.

Researchers found that achievement of platelet response was independent of the dosage. Based on the study results, 700 µg was selected as the dosage to use in future studies.

Researchers also noted that the study design lacked a control group, and suggested future studies to further analyze the safety of Nplate in MDS patients.

For more information on the study, please see the study in the Journal of Clinical Oncology (abstract). For information in the interim results, please see the related MDS Beacon article.