Researchers at Mass General Brigham Cancer Institute announced on April 11 that the investigational drug mezagitamab increased platelet counts in patients with immune thrombocytopenia (ITP), according to results from a phase 2 clinical trial. The findings were published in the New England Journal of Medicine.
The study is significant because about one in five people with ITP do not respond to existing treatments, leaving them at higher risk for bleeding and a lower quality of life. ITP is an autoimmune disorder marked by both increased destruction and decreased production of platelets.
"This is a novel therapy that works fast and attacks the underlying mechanism of the disease," said lead author David J. Kuter, MD, DPhil, a hematologist with Mass General Brigham Cancer Institute. "We saw that it can have a rapid effect, normalizing platelet counts in 48 hours and improving quality of life."
Mezagitamab was originally developed as a possible cancer treatment but targets CD38 proteins found on several types of immune cells involved in autoimmune responses. In this phase 2 trial sponsored by Takeda Development Center Americas, adults from Bulgaria, China, Croatia, Greece, Italy, Japan, Slovenia, Spain, and Ukraine who had persistent ITP were enrolled. Participants received different doses or placebo injections under their skin; after early safety data appeared positive mid-study, more participants received the highest dose tested.
Results showed that treatment with mezagitamab led to higher platelet counts than placebo and had similar safety outcomes. Specifically through week 16 of the study period, 91% (10 out of 11) participants receiving the highest dose reached target platelet levels compared to only 23% (3 out of 13) among those given placebo.
"This study was designed as a dose-ranging proof-of-concept trial. We are now conducting a phase 3 clinical trial of 600-mg dose of mezagitamab with Mass General Brigham Cancer Institute serving as the leading site in North America," said Kuter.
