Rozrolimupab is a recombinant antibody mixture product consisting of 25 Rhesus D specific full length human antibodies. Rozrolimupab is in development for the treatment of immune thrombocytopenic purpura (ITP) and for use as anti-D prophylaxis (ADP) to prevent hemolytic disease of newborns (HDN). ITP is a bleeding disorder caused by abnormally low platelet levels, making it difficult for the blood to clot. Rozrolimupab has received an orphan drug designation from the FDA for treatment of ITP. HDN occurs when Rhesus D negative women become sensitized towards Rhesus D through carrying a Rhesus D positive child. While this does not normally harm the first infant, it may trigger a maternal antibody response in subsequent pregnancies causing fetal red blood cell destruction, known as HDN. Untreated HDN may cause severe abnormalities, or fetal loss.
Clinical phase 2 data were published in the premier hematology journal Blood in November 2012. The results of this dose-finding clinical phase 2 study indicate that Sym001 holds promise to be an effective and well tolerated therapy for ITP. The study was run in 41 centers in the US, Europe and Asia, and thus demonstrates the regulatory authorities willingness to accept clinical trials for a complex product consisting of 25 well-characterized monoclonal antibodies. As rozrolimupab is outside Symphogen's oncology focus, further development will await identification of a global partner.
The clinical use of blood-derived anti-D immunoglobulin interventions has significantly reduced the risk of serious complications from HDN and improved treatment of ITP. However, the current supply of blood-derived anti-D immunoglobulins is dependent on a consistent donor population, and in some regions, anti-D regimens are limited to the prevention of HDN due to supply issues, not allowing its use in treating ITP.
As developed by Symphogen, rozrolimupab is a well characterized, consistent antibody mixture expected to provide significant benefits over blood derived products for the treatment of both HDN and ITP.