After rejection and appeal, Omeros saddles up for 2nd charge at transplant drug approval

A year and a half after its stem-cell-associated blood clot med was rejected by the FDA, Omeros is gearing up to head back to the regulator for another attempt.

The biotech is preparing to resubmit its application for narsoplimab in hematopoietic stem cell transplant-associated thrombotic microangiopathy, the company revealed in its fourth-quarter earnings report. In fact, Omeros has already requested a meeting with the agency, expected to take place in the second quarter, to confirm additional information that will need to be provided.

Omeros’ ambitions for narsoplimab appeared to run out of road back in October 2021, when the FDA rejected the monoclonal antibody. At the time, the agency raised concerns about estimating the treatment effect of the drug based on the data provided and requested extra information.

The biotech didn’t throw in the towel straight away, instead appealing the FDA’s decision. That process wound up in November 2022 with the FDA rewarding Omeros’ perseverance by setting out a potential path to resubmit the application.

This proposed resubmission should include “a comparison of the existing response data from the completed pivotal trial to a threshold derived from an independent literature analysis and evidence of increased survival from patients in the pivotal trial compared to an appropriate historical control group,” Omeros explained at the time.

Now, the company has requested a Type B meeting with the FDA’s Division of Non-Malignant Hematology in April or early May to confirm exactly what information is required.

Narsoplimab is the company’s lead monoclonal antibody, which is designed to target mannan-binding lectin-associated serine protease-2. While the stem cell transplant indication has proved tricky to secure approval, Omeros has been exploring other avenues for the drug.

For example, the biotech remains on schedule to release top-line data from its ARTEMIS-IGAN trial of narsoplimab in IgA nephropathy in the third quarter of the year.

There is also “mutual interest in working with the U.S. government” to explore the antibody’s potential in COVID-19 and acute respiratory distress syndrome, CEO Gregory Demopulos, M.D., said in the release. Narsoplimab was included in the I-SPY trial, where it reduced mortality risk but didn’t shorten recovery time in critically ill COVID-19 patients.