Photo by Chad McNeeley
Transplant preparation
MARSEILLE—An investigational drug has successfully treated a severe case of transplant-associated thrombotic microangiopathy (TA-TMA), according to a presentation at the 43rd Annual Meeting of the European Society for Blood and Marrow Transplantation.
The drug is OMS721, a monoclonal antibody targeting mannan-binding lectin-associated serine protease-2 (MASP-2), the effector enzyme of the lectin pathway of the complement system.
The patient received OMS721, which is being developed by Omeros Corporation, under a compassionate-use protocol.
Marco Zecca, MD, of the Fondazione IRCCS Policlinico San Matteo in Italy, and his colleagues provided details on this patient in a poster presented at the meeting (Physician Poster Abstracts-Day 1, abstract A437).
The female patient had undergone a hematopoietic stem cell transplant to treat Diamond‐Blackfan anemia. At age 14, she received a transplant from an HLA-compatible, unrelated donor.
Seven months later, she was diagnosed with TA-TMA. The patient was initially treated with eculizumab but had to stop taking the drug after she developed acute pulmonary edema.
She was then treated with plasma exchange but experienced a TA-TMA relapse at 11 months. The patient was again treated with eculizumab and again had to discontinue the drug after developing acute pulmonary edema.
The patient’s condition continued to worsen, and she soon required hemodialysis 3 times a week as well as daily platelet transfusions.
Dr Zecca requested OMS721 as compassionate-use treatment for the patient, and Omeros complied.
Two months after starting OMS721, the patient was able to discontinue hemodialysis and decrease her platelet transfusion requirements. She did not experience any adverse events related to OMS721.
Recently, the patient’s dose was tapered, but she developed a viral infection that reactivated her TA-TMA.
A return to the original dose of OMS721 was successful. Now, the patient no longer requires dialysis or transfusions.
“This patient had severe TMA that I believe would have caused her death,” Dr Zecca said. “Her positive response to OMS721 treatment, both initially and following her virus-induced relapse during tapering, was impressive.”
“The results of OMS721 treatment in this challenge-rechallenge scenario underscore the important effects of the drug. Since the poster was produced, her TMA has remained in remission, and we have been able to discontinue her platelet transfusions. Her rapid response has been heartening, and we all are grateful for this remarkable outcome.”
