UCB announced that the U.S. Food and Drug Administration (FDA) has accepted the company's filing to review a Biologic License Application (BLA) for its investigational treatment rozanolixizumab, and that the Agency has granted Priority Review. Rozanolixizumab is a subcutaneous (SC) monoclonal antibody targeting the neonatal Fc receptor (FcRn) for the treatment of adults with generalized myasthenia gravis (gMG) who are anti-acetycholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody positive. A FDA Priority Review designation is typically granted by the Agency to a medicine which, if approved, could deliver significant improvements in the safety or effectiveness of the treatment, diagnosis, or prevention of serious conditions when compared to standard applications.

Priority Review designation means the FDA's goal is to take action on an application within 6 months, compared to 10 months under standard review. In 2019, the U.S. FDA granted orphan drug designation to rozanolixizumab for the treatment of MG. The safety and efficacy of rozanolixizumab have not been established and they are not currently approved for use in any indication by any regulatory authority worldwide.

The FDA Priority Review designation follows the recent European Medicines Agency (EMA) validation of the Marketing Authorization Application (MAA) for rozanolixizumab for the treatment of adults with AChR or MuSK antibody positive gMG who require treatment in addition to steroids or non-steroidal immunosuppressants. Validation confirms that the application is complete and the formal review process by the EMA's Committee for Medicinal Products for Human Use (CHMP) can begin. Orphan designation was granted by the European Commission in April 2020 to rozanolixizumab for the treatment of myasthenia gravis.

UCB expects to receive feedback from both the FDA and EMA during the second quarter of 2023. Data from the MycarinG study: The Priority Review BLA and the MAA are based on data from the pivotal Phase 3 MycarinG study (NCT03971422), in which rozanolixizumab demonstrated statistically significant and clinically meaningful improvements in MG-specific outcomes in patients with AChR MuSK antibody positive MG. In the primary endpoint, rozanolixizumab significantly reduced MG-ADL from baseline to Day 43.

Rozanolixizumab showed an LS mean difference vs placebo (95% CI) of -2.59 points at the 7mg/kg dose and -2.62 points at the 10mg/kg dose. Furthermore, a greater percentage of patients in the rozanolixizumab 7mg/kg and 10mg/kg arms than the placebo arm achieved a 2.0-point or greater improvement (p<0.001) in MG-ADL, a 3.0-point or greater improvement in Quantitative Myasthenia Gravis (QMG) scores and a 3.0-point or greater improvement in Myasthenia Gravis Composite (MGC) scores, demonstrating clinically meaningful reductions in these assessments. Rozanolixizumab demonstrated an acceptable safety and tolerability profile with similar occurrences of TEAEs between both doses.

A higher proportion of TEAEs occurred in the active treatment arms versus placebo (81.3% for 7 mg/kg, 82.6% for 10 mg/kg and 67.2% for placebo) and were comparable between the rozanolixizumab groups. The most frequently reported TEAEs were headache, diarrhea, pyrexia, and nausea. A higher incidence of headache was reported in the rozanolixizumab groups versus placebo, with most cases mild to moderate and severe cases generally managed with non-opioid analgesics.

Treatment discontinuation rates due to TEAEs were low. In the MycarinG study, 200 patients were randomised 1:1:1 to receive weekly rozanolixizumab 7 mg/kg (N=66), 10 mg/kg (N=67) or placebo (N=67) for 6 weeks, which was followed by an 8-week observation period. UCB is currently investigating two potential therapies with different modes of action for the treatment of gMG.

Alongside rozanolixizumab, a NDA for zilucoplan – a subcutaneous self-administered peptide inhibitor of complement component 5 (C5 inhibitor) has recently been filed with the U.S. FDA for the treatment of adults with AChR antibody positive gMG. Additionally, zilucoplan received MAA validation from the EMA for the treatment of adults with AChR antibody positive gMG and who require treatment in addition to steroids or non-steroidal immunosuppressants.