Enrollment Begins for Zaltenibart in PNH

Zaltenibart (OMS906) is Omeros’ investigational inhibitor of MASP-3, the key and most proximal activator of the alternative pathway of complement. Zaltenibart inhibits the intravascular hemolysis treated by C5 inhibitors as well as the extravascular hemolysis caused by C5 inhibitors in patients suffering from PNH while leaving intact the infection-fighting lytic arm of the classical pathway of complement.

A total of 120 clinical investigative sites across 30 countries have been chosen for clinical trial participation in the zaltenibart Phase III program in PNH, a good number of which have already identified pools of PNH patients ready to participate in the zaltenibart trials, and Omeros continues collaborating with sites to identify additional eligible and already available PNH patients. Data needed for submission of the biologics licensing application (BLA) and global approval dossiers for zaltenibart in PNH remain on track for the fourth quarter of 2026.

The Phase III clinical trials will evaluate intravenous zaltenibart dosed once every eight weeks. Currently marketed upstream complement inhibitors require dosing orally twice daily, orally three times daily in conjunction with C5 inhibitor treatment, or subcutaneous infusions twice weekly. Zaltenibart’s conveniently infrequent dosing together with its ability to inhibit both intravascular and extravascular hemolysis provide a meaningful differentiation from the other PNH therapies. Phase II data have previously been presented at the American Society of Hematology and European Hematology Association Annual Meetings and demonstrate that zaltenibart effectively inhibits both intravascular and extravascular hemolysis while achieving gender-normal hemoglobin levels in both men and women. No safety signal of concern has been observed with zaltenibart.

The zaltenibart Phase III program includes two clinical trials, one in patients who are not receiving complement-inhibitor treatment at the time of study entry and another in patients who have an inadequate response to treatment with either ravulizumab or eculizumab. Both clinical trials compare the efficacy and safety of zaltenibart monotherapy to that of the C5 inhibitors eculizumab and ravulizumab, and both FDA and European regulators have agreed with the trial designs. All zaltenibart drug product required for the Phase III program has been manufactured, and comparator C5 inhibitors have been sourced. These study designs provide head-to-head comparisons and should provide data to demonstrate superiority of zaltenibart over the C5 inhibitors in these patient populations. These comparison data may form the basis for comparative superiority claims for promotion, enhanced market access, and pricing reflective of zaltenibart’s advantages. In further preparation for potential commercialization of zaltenibart, recommendations regarding patient-reported-outcome (PRO) measures were sought and received from the German Federal Joint Committee, the decision-making body in the German healthcare system that specifies which medical treatments are reimbursed by the statutory health insurance funds and specialized in PRO measures. Recommended PRO measures were incorporated into the zaltenibart Phase III design and are expected to be helpful in securing appropriate pricing.

The global market size for PNH is reported at $3.8 billion dollars in 2023 and projected at over $11.7 billion dollars in 2034. Currently, a Phase II clinical trial of zaltenibart to treat C3 glomerulopathy is ongoing, and additional indications related to the alternative pathway are being evaluated for clinical trials.