Phase 2 Study Finds Rozanolixizumab Effective, Tolerable, and Safe in Patients with Primary ITP


These findings suggest that rozanolixizumab has good potential as a treatment for this patient population.

Final results from a phase 2 study of rozanolixizumab in patients with persistent or chronic primary immune thrombocytopenia (ITP), published in Blood Advances, suggested that the agent was effective at increasing platelet counts with apparent tolerability and safety.1

Given these findings, researchers suggested that rozanolixizumab has good potential as a treatment for this patient population.

"People who have primary ITP may experience low platelet count that puts them at risk for severe bleeding, and there are limited options to reduce this risk," Tadeusz Robak, PhD, professor of Hematology at the Medical University of Lodz, Poland, said in a press release.2 "New treatment options for ITP that have the potential to provide improvement in platelet count are urgently needed, and I am encouraged by the results in this phase 2 study, which is now being tested also in a chronic use program in phase 3."

The multi-center, open-label, multiple-dose, phase 2 study assigned 66 patients with persistent or chronic primary ITP to 1 of 5 groups with different dosing regimens (5 x 4 mg/kg, 3 x 7 mg/kg, 2 x 10 mg/kg, 1 x 15 mg/kg, or 1 x 20 mg/kg; multiple doses were administered at weekly intervals), receiving rozanolixizumab by subcutaneous infusion. Study participants were monitored for an 8-week observation period after completion of treatment.

The dual primary end points for the study were safety and tolerability of subcutaneous rozanolixizumab infusion, and key secondary end points included clinical efficacy, measured by platelet count, and pharmacodynamic effects, measured by immunoglobin G (IgG).

Overall, platelet counts of 50 109/L or greater were achieved at least once at any time after multiple infusions (5 x 4, 3 x 7, or 2 x 10 mg/kg; 35.7%, 35.7%, and 45.5% of patients, respectively) or single infusions (15 or 20 mg/kg; 66.7% and 54.5% patients, respectively). Moreover, minimum mean IgG levels and maximum mean platelet counts both occurred by day 8 in the higher (15 and 20 mg/kg) single-dose cohorts and maximum platelet count occurred by day 11 onward in the multiple-dose cohorts.

Importantly, no clinically meaningful changes were observed in IgA, IgM, IgE, or albumin levels.

In total, 51 (77.3%) of 66 patients reported 1 or more adverse events (AEs), which were all mild-to-moderate and most commonly headaches (26 [39.4%] of 66), of which 15 were treatment related. Further, 4 patients had serious AEs, but none were treatment related. No AEs resulted in discontinuation of rozanolixizumab and no serious infections occurred.

Researchers indicated that these safety, tolerability, efficacy, and pharmacodynamic data support the ongoing phase 3 development of rozanolixizumab as a maintenance treatment in patients with primary ITP (NCT04200456). In addition, investigators suggested the rapid onset of action seen in this study provides potential for further application of rozanolixizumab in ITP in which a platelet increase within 1 week is required.

Rozanolixizumab is a subcutaneously administered, humanized monoclonal antibody that binds specifically to human Fc receptor (FcRn). The agent was designed to block the interaction of FcRn and IgG, inhibiting IgG recycling and inducing the removal of pathogenic IgG autoantibodies.

“These data build on the growing body of evidence that targeting the FcRn pathway has the potential to treat people with rare IgG autoantibody-mediated diseases such as primary ITP,” James Bussel, MD, professor emeritus of Pediatrics at Weill Cornell Medicine, said in the release. “Publication of these findings in Blood Advances encourages us to continue to deepen our understanding of primary ITP and the ways rozanolixizumab may help treat people living with this disease.”

Rozanolixizumab was granted orphan drug designation for the treatment of ITP on April 30, 2018 by the FDA and on January 11, 2019 by the European Commission. However, it is not currently approved by any regulatory authority worldwide.


1. Robak T, Kaźmierczak M, Jarque I, et al. Phase 2 multiple-dose study of an FcRn inhibitor, rozanolixizumab, in patients with primary immune thrombocytopenia. Blood Advances. doi: 10.1182/bloodadvances.2020002003

2. Final Phase II Results for UCB's Rozanolixizumab in Primary Immune Thrombocytopenia (ITP) Published in Blood Advances [news release]. Brussels. Published September 9, 2020. Accessed September 16, 2020.

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