View of the inner bone marrow vasculature and residing cells of a mouse (cyan: endothelial and blood cells; magenta: blood cells, arteries and arterioles; white: smooth muscle cells. Image credit: Konstantinos Kokkaliaris (CC BY-NC-ND 2.0)
Multiple myeloma is a type of bone cancer. It affects the immune cells that make antibodies, known as plasma cells. These immune cells live in the bone marrow. As with many types of cancer, the chance of survival is highest when multiple myeloma is diagnosed early. It has three stages, labelled I, II, and III. People with stage I or II disease have better outcomes than those with stage III, but the exact reasons are unclear.
Bone marrow contains lots of different types of cells, which can affect the growth of a tumour. These include cancer-targeting cells, called killer T-cells, and cancer-supporting cells called myeloid cells. Understanding these cells and how they interact could shed light on the different stages of multiple myeloma. One way to do this is to use single cell sequencing, which looks at the genes in use inside each cell at any one time.
Zhong, Hao, Zhang, Jiang et al. examined the bone marrow of two healthy donors and nine people with different stages of multiple myeloma. This revealed two new groups of plasma cells. One group, highest in stage II patients, was protective, with the potential to kill cancer cells. The other, highest in people with more aggressive disease, was harmful, with the potential to divide rapidly. The sequencing also identified molecules that might be useful drug targets for the future. These included a gene that drove growth in the dangerous plasma cells, and several that might help tumours escape from the immune system.
It is becoming increasingly clear that the environment around a tumour has a huge role to play in its progression. Understanding how this environment changes over time could aid in the development of more targeted treatments. The next step is to find out more about the molecules identified here.
