Rare Blood Disorders R&D

Sanofi R&D teams aim to transform the standard of care for people who are affected by rare blood disorders. The company's unique R&D program builds on a legacy of innovation, stemming from the development of the first extended half-life clotting factors for treating hemophilia A and B, branching out to the first approved treatment for acquired thrombotic thrombocytopenic purpura (aTTP), and cutting-edge research in cold agglutinin disease.

Rare Blood Disorders Pipeline

Sanofi researchers are working closely with patient communities to set priorities and harnessing pioneering technology platforms to develop innovative treatments. Since 2018 Sanofi has welcomed innovative companies Bioverativ, Principia, and Ablynx, and leveraged technology from strategic partner Alnylam, to reinforce its foundations in rare blood disorders R&D. With elegant molecular designs, TAILORED COVALENCY®, NANOBODY® molecules, small interfering RNA (siRNA) technology, and a genomic medicine program, Sanofi's R&D teams are working to change expectations for how these conditions could be managed in the future.

Sanofi's R&D Pipeline


Hemophilia, a rare, genetic blood disorder that affects blood clotting, is the cornerstone of Sanofi's Rare Blood Disorders program. To address common limitations experienced by patients, our scientists are pursuing two approaches to hemophilia management that are now in late-stage clinical trials. One investigational treatment is designed to provide extended protection for people with hemophilia A or B, with and without inhibitors (antibodies against factor therapy), designed as a subcutaneous dose. Sanofi is also working in partnership with biopharmaceutical company Sobi to develop a separate investigational treatment designed to provide high, sustained factor activity levels for people with hemophilia A.

Sanofi believes all patients should have access to therapy. Together with Sobi, the company expanded its support of the World Federation of Hemophilia Humanitarian Aid Program in 2021 by pledging to donate up to 500 million international units (IUs) of clotting factor for five years, fulfilling their 2014 pledge to donate up to 1 billion IUs of factor for humanitarian use. This is an important step toward providing a predictable supply of therapies to people in need.

The Science Behind Sanofi's Hemophilia Pipeline
Helping Change the Lives of People with Hemophilia

Acquired Thrombotic Thrombocytopenic Purpura (aTTP)

In 2018, Sanofi launched the first approved treatment for aTTP, a rare, life-threatening, immune-mediated blood disorder.1 Patients with aTTP go through extensive clot formation in small blood vessels throughout the body, which leads to severe thrombocytopenia (very low platelet count), loss of red blood cells through destruction, restricted blood supply to parts of the body. Sanofi's aTTP therapy is based on Nanobody® technology.

NANOBODY® Technology Platforms

Immune Thrombocytopenic Purpura (ITP)

In people with immune Thrombocytopenic Purpura (ITP), immune cells destroy healthy platelets, which can lead to excessive bruising and bleeding. Clinical researchers at Sanofi are evaluating two investigational medicines to treat ITP. One is an oral, reversible-covalent molecule, designed using TAILORED COVALENCY®, that inhibits Bruton’s tyrosine kinase (BTK), an enzyme involved in immune-mediated diseases.

Cold Agglutinin Disease (CAD)

Cold Agglutinin Disease (CAD) is a rare type of chronic, autoimmune, hemolytic anemia. In people with CAD, the body’s immune system mistakenly attacks and destroys healthy red blood cells (hemolysis) by activating the "classical complement" pathway, which is part of the innate immune system. People with CAD may experience chronic anemia, profound fatigue, acute hemolytic crisis, and other potentially serious complications.

Sanofi researchers are studying the body's complement system, which involves more than 30 proteins2 acting in concert to destroy pathogens. In a cascade of tightly coordinated events, these proteins trigger inflammation and form a membrane attack complex, which then bursts and ingests bacteria. Sanofi R&D teams are investigating how blocking one of three pathways that triggers this cascade could keep the autoimmune response in check while allowing the body to maintain its defenses.

Brad's Story: Living with Cold Agglutinin Disease

Sickle cell disease

People with sickle cell disease, a lifelong blood disorder, have a mutation that results in an abnormal type of hemoglobin, the protein in red blood cells that carries oxygen to cells throughout the body. This mutation can lead to chronic anemia, severe painful crisis, multiple end-organ damage, and complications such as stroke. Currently, people living with this rare blood disorder have few treatment options. In partnership with Sangamo, Sanofi R&D teams are developing a gene-editing therapy based on zinc-finger nuclease technology for patients with sickle cell disease.

Related articles

Your Health: Rare Blood Disorders

The Science Behind Sanofi's Hemophilia Pipeline

New Frontiers in Genomic Medicine at Sanofi

Brad's story: Living with CAD

Inside Sanofi's Hemophilia Research


  1. Approved first in Europe (2018), then the US (2019)
  2. Specifically, phagocytic lysis proteins
  • Berentsen S, Malecka A, Randen U, Tjønnfjord GE (2020) Clin Adv Hem Oncol 18:35-44
  • Berentsen S, et al. (2006) Haematologica 91:460–466
  • Bylsma LC, et al. (2019) Blood Adv 3:2980–2985
  • Broome C, et al. (2020) Res Pract Thromb Haemost. 00:1–8
  • Hill QA, et al. (2019) Blood 134:S4790
  • Machin N, Ragni MV (2018) J Blood Med 9:135-140; doi: 10.2147/JBM.S159297
  • National Heart, Lung, and Blood Institute. Thrombotic Thrombocytopenic Purpura. Accessed at https://www.nhlbi.nih.gov/health-topics/thrombotic-thrombocytopenic-purpura on 17 March 2021
  • Seth Chhabra E, et al. (2020) Blood 135(17):1484–1496; 10.1182/blood.2019001292
  • Williams TN, Thein SL (2018) Ann Rev Genom Hum Gen 19:113-147; doi: 10.1146/annurev-genom-083117-021320