New Developments

Immunological Applications for leronlimab (PRO 140)

The target of leronlimab (PRO 140) is the important immunologic receptor CCR5. The CCR5 receptor is more than the door for HIV to enter T-cells; it is also a crucial component in inflammatory responses. This opens the potential for multiple pipeline opportunities for leronlimab (PRO 140).

The CCR5 receptor is a protein located on the surface of white blood cells that serves as a receptor for chemical attractants called chemokines. Chemokines are the key orchestrators of leukocyte trafficking by attracting immune cells to the sites of inflammation.

At the site of an inflammatory reaction, chemokines are released. These chemokines are specific for CCR5 and cause the migration of T-cells to these sites promoting further inflammation. The mechanism of action of leronlimab (PRO 140) has the potential to block the movement of T-cells to inflammatory sites, which could be instrumental in diminishing or eliminating inflammatory responses. Some disease processes that could benefit from CCR5 blockade include new reactions to cancer, transplantation rejection, autoimmunity and chronic inflammation such as rheumatoid arthritis and psoriasis.

Due to its mechanism of action, leronlimab (PRO 140) has significant advantages in terms of safety and reduced side effects over other CCR5 antagonists. Prior studies have demonstrated that leronlimab (PRO 140) does not cause direct activation of T-cells. We have already reported encouraging human safety data for our clinical trials with leronlimab (PRO 140) in HIV-infected patients.

We have initiated our first clinical trial with leronlimab (PRO 140) in an immunological indication - a Phase 2 clinical trial with leronlimab (PRO 140) for Graft versus Host Disease (GvHD) in patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) who are undergoing bone marrow stem cell transplantation. GvHD represents an unmet medical need, with patients who contract GvHD during stem cell transplant having a significantly decreased 1-year survival rate with relapsed GvHD as the leading cause of death. Leronlimab (PRO 140) is also being investigated in animal models of cancer progression and autoimmunity with positive results. Our animal studies in GvHD have been submitted for publication in peer-reviewed journals.

As we progress in evaluating leronlimab (PRO 140) in different pathways of human disease and inflammation, we are encouraged by the opportunity to build a broad pipeline of indications.