Targeting GM-CSF Signaling with KB003: A Therapeutic Approach for Chronic Myelomonocytic Leukemia

Chronic Myelomonocytic Leukemia (CMML) is a type of blood cancer with various genetic causes. It can lead to low blood cell counts, bone marrow issues, an enlarged spleen, and can change into a more severe form called Acute Myeloid Leukemia (AML). CMML is aggressive and has a poor survival rate, with only about 20% of patients living for three years. Current treatments are not very effective and are mostly based on studies of a related condition, Myelodysplastic Syndromes (MDS).

Researchers have found that CMML cells are very sensitive to a substance called GM-CSF, which can cause them to grow. They have tested a drug called KB003, made by KaloBios Pharmaceuticals, to see if it can stop GM-CSF from helping these cells grow. They used two different tests to see how well KB003 could block GM-CSF. In one test, they used a type of cell called U937 and measured how much IL-8 was produced when GM-CSF was added. In the other test, they used a cell line called MO7e and looked at how KB003 affected the cells' survival.

They also used bone marrow samples from 10 CMML patients to test how KB003 affected the cells' ability to grow and survive. They found that KB003 could reduce the number of certain types of cells and their ability to form colonies, which is a sign of growth. The drug was most effective against cells that had a protein called CD38 on their surface.

The study shows that blocking GM-CSF with KB003 can help reduce the survival of CMML cells in the lab. This suggests that KB003 and similar drugs that target GM-CSF might be worth looking into for treating CMML. Cells that are more sensitive to GM-CSF and have CD38 might be the ones that start the disease, and could be important for treating CMML with drugs like KB003.