March 2022

Priothera – FDA and EMA Grant Orphan Drug Designation to mocravimod for the treatment of Acute Myeloid Leukemia (AML) in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT)

Mocravimod is being developed as a potential best-in-class adjunctive and maintenance therapy to enhance the curative potential of HSCT for AML patients.
A global registration-enabling Phase 2b trial assessing mocravimod in AML patients undergoing allogeneic HSCT is planned in H2 2022.

Dublin, Ireland – 3rd March 2022 – Priothera, a late-clinical stage biotechnology company pioneering the development of its S1P receptor modulator drug, mocravimod, today announced that the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have both granted orphan drug designation (ODD) to mocravimod for the treatment of Acute Myeloid Leukemia (AML) in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). EMA’s ODD follows a recommendation from the Committee for Orphan Medicinal Products (COMP).

Florent Gros, Co-Founder and CEO of Priothera, commented: “The orphan drug designations we received for mocravimod from both the FDA and EMA are important milestones towards addressing the urgent, unmet needs of AML patients. Allogenic stem cell transplantation is the only potentially curative approach for AML patients but has unacceptably high mortality rates with current treatments. We are looking forward to initiating the global Phase 2b clinical trial with mocravimod in multiple centers in the US, Europe and Asia in the coming months.”

Mocravimod, a sphingosine 1 phosphate (S1P) receptor modulator which has been previously tested in multiple autoimmune indications, is being developed to enhance the curative potential of HSCT. Moreover, it has shown a clinically relevant benefit in an early clinical study in patients with hematologic malignancies undergoing HSCT.

A multicenter Phase 2b study evaluating the efficacy and safety of mocravimod as an adjunctive and maintenance therapy to HSCT in adult AML patients is planned for the second half of 2022. The study will include approximately 250 patients in several countries in Europe, the US and Asia, upon approvals from respective health authorities.

Orphan drug designation is reserved for medicines treating rare, life-threatening or chronically debilitating diseases.

About mocravimod

Mocravimod (also known as KRP203), is a novel, synthetic, sphingosine 1-phosphate receptor (S1PR) modulator with a long duration in the body. Phase 1 and Phase 2 trials successfully assessed mocravimod for safety and tolerability in several autoimmune indications. Promising data from a Phase 1b/2a clinical study in patients with hematological malignancies led Priothera to further develop mocravimod for the treatment of blood cancers.

Mocravimod will be investigated in a Phase 2b/3 study as a potential treatment for patients with Acute Myeloid Leukemia (AML) receiving allogeneic hematopoietic stem cell transplantation (HSCT). Allogenic HSCT is the only potentially curative approach for AML patients, but current treatments have unacceptably high mortality and morbidity rates.

Priothera leverages S1PR’s unique mode of action to maintain anti-leukemia activity – graft-versus leukemia (GVL) – while reducing tissue damage resulting from graft-versus-host disease (GVHD), a consequence of allogenic HSCT. This novel treatment approach – the only S1PR modulator treating blood cancers – tackles a high unmet medical need and intends to add quality life to patients.


About Priothera

Priothera is leading the way in developing orally applied sphingosine 1 phosphate (S1P) receptor modulators for the treatment of hematological malignancies. S1P receptor modulators are known to largely reduce egress of T cells from lymphatic tissues and not being immunosuppressants, thereby allowing for inhibition of graft-versus-host-disease (GvHD) while maintaining graft-versus-leukemia benefits in patients receiving HSCT.

Priothera which was founded in 2020 by an experienced team of drug development experts is headquartered in Dublin, Ireland. The Company is backed by international founding investors Fountain Healthcare Partners (Dublin, Ireland), funds managed by Tekla Capital Management, LLC (Boston, Massachusetts), HealthCap (Stockholm, Sweden) and EarlyBird Venture Capital (Berlin, Germany).

For more information please visit:


Florent Gros, CEO
E :

MEDiSTRAVA Consulting
Sylvie Berrebi, Sandi Greenwood, Frazer Hall
T: +44 (0)7714 306525