Eager to tout pivotal win, Omeros however keeps key parameters shrouded
Omeros has brought some stellar pivotal data to the FDA to build a case for its blood clot drug, narsoplimab. They just can’t say exactly how they got to the conclusion yet.
Reporting preliminary data from its single-arm, open-label trial, the Seattle-based biotech said 56% of the patients — who were experiencing thrombotic microangiopathy following hematopoietic stem cell transplants — receiving at least one dose of narsoplimab achieved complete responder status. Among the subset who received at least four weeks of dosing, 68% met the criteria.
So what separates a responder from a non-responder?
That will have to “remain confidential for competitive business reasons,” the company said in a statement, stressing that FDA regulators agreed to the “highly rigorous” set of response criteria.”
Omeros shares $OMER traded up 7.65% to $15.47.
While Omeros had originally designated “clinical activity as assessed by platelet count” as the primary endpoint, the company changed it at the request of the FDA, a spokesperson told Endpoints News. The secondary endpoints were also modified.
They include: 100-day survival rates of 65% among those receiving at least one dose, 81% among those who received at least four weeks of treatment, and 93% among the complete responder group; “substantial and statistically significant improvements in platelet count, LDH and haptoglobin”; and increased hemoglobin across all groups.
“The response rate in this high-risk population would be expected to be 10 to 15 percent with a 100-day survival rate of less than 20 percent,” said Rafael Duarte, who heads the hematopoietic program at University Hospital Puerta de Hierro Majadahonda in Madrid, in a glowing statement. “The response rate and 100-day survival achieved with narsoplimab in this trial demonstrate an unprecedented effect in this condition.”
Omeros disclosed that 21% of patients died during the trial “due to causes common in stem cell transplant” but no others discontinued for adverse events, which ranged from nausea, vomiting and diarrhea to hypokalemia, neutropenia and fever.
The trial was designed to enroll 89 patients, although the company didn’t specify the final number included for the analysis.
In a previous data cut involving 19 patients, Omeros highlighted that the drug helped extend median overall survival to 347 days, a big improvement compared to the 21 days recorded in literature.
The rolling BLA that they initiated in October is expected to be completed by the first half of next year, according to CEO Gregory Demopulos: “the nonclinical sections have been submitted and the data from this trial form the efficacy basis of the application.”
Previously known as OMS721, narsoplimab is decorated with orphan drug and breakthrough therapy designations from the FDA. If approved, the MASP-2 inhibitor would be Omeros’ second drug on the market.