Rare Pediatric Designation Granted by the FDA to Nomacopan for HSCT Thrombotic Microangiopathy


Findings from a phase 3 trial assessing nomacopan in patients with hematopoietic stem cell transplant–related thrombotic microangiopathy helped to support a rare pediatric designation from the FDA for the agent.

The FDA has granted rare pediatric designation to nomacopan for patients with hematopoietic stem cell transplant-related thrombotic microangiopathy (HSCT-TMA), according to a press release from Akari Therapeutics.1

In addition to its rare pediatric designation, nomacopan has also previously received orphan drug and fast track designations. Due to this, the agent may be eligible for a priority review voucher.

“Families with children who have a hematopoietic stem cell transplant-related TMA face grim prospects with high mortality rates and no approved treatment options,” Rachelle Jacques, president and chief executive officer of Akari, said in the press release. “The rare pediatric disease designation was created by the FDA because families need so much more than hope for their children; they need meaningful treatment options. We are pleased the FDA has recognized the significant needs that exist for children with HSCT-TMA, and we will continue to urgently pursue our mission to advance nomacopan to approval on their behalf.”

Nomacopan is a second-generation complement inhibitor that prevents the release of C5a and formation of C5b-9.2 This treatment also inhibits leukotriene B4 or LTB4, which are part of the immune and inflammatory response. The biophysical properties of this treatment allow for it to be used either subcutaneously, intravenously, topically, or through inhalation.

The agent is being evaluated as part of a phase 3 open-label, multicenter study (NCT04784455) that is broken into 2 parts: The goal of part A is to determine the dosing schedule and part B will evaluate efficacy and safety. A total of 50 patients are estimated to enroll and undergo treatment with nomacopan after having received HSCT-TMA within the last 100 days.

The primary end points are red blood cell transfusion independence for 28 days or more prior to a scheduled visit up to week 24, and urine protein creatine ratio of 2 mg/mg or more. Key secondary end points included renal function improvement, platelet transfusion independence, normalization of lab parameters, and safety and tolerability of nomacopan.

Patients who were between 6 months and 18 years old, had undergone allogeneic or autologous HSCT, or had a TMA diagnosis within 100 days of HSCT were eligible for treatment. Additional eligibility criteria included having a clinical or histological diagnosis of TMA, as well as a provision of informed consent or assent.

Patients who weighed less than 5 kg, had a positive direct Coomb’s test, and did not receive nomacopan within 14 days of TMA diagnosis were not eligible for treatment. Those who had an active infection, grade 4 acute graft-versus-host disease, previously received eculizumab (Soliris) or a complement blocker therapy, had known hypersensitivity to an active ingredient, and a positive ADAMTS13 test were also excluded.


  1. Akari Therapeutics granted FDA rare pediatric disease designation of nomacopan for the treatment of pediatric HSCT-TMA. News release. Akari Therapeutics. November 10, 2022. Accessed November 10, 2022. https://bit.ly/3UNfF5p
  2. Akari Therapeutics. Nomacopan. Accessed November 10, 2022. https://bit.ly/3Usnxto
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