Hairy Cell Leukemia - Research Directions

Research Directions

The Hairy Cell Leukemia Consortium was founded in 2008 to address researchers' concerns about the long-term future of research on the disease. Partly because existing treatments are so successful, the field has attracted very few new researchers.

Three immunotoxin drugs are in Phase II trials at the NIH's National Cancer Institute in the U.S.: BL22, HA22 and LMB-2. All of these protein-based drugs combine part of an anti-B cell antibody with a bacterial toxin to kill the cells on internalization. BL22 and HA22 attack a common protein called CD22, which is present on hairy cells and healthy B cells. LMB-2 attacks a protein called CD25, which is not present in HCL-variant, so LMB-2 is only useful for patients with HCL-classic or the Japanese variant. All three of these therapies are available only at the National Cancer Institute in Bethesda, Maryland, USA. While initial results are generally favorable, it is likely to be a number of years before these drugs are available on the market.

Other clinical trials are studying the effectiveness of cladribine followed by rituximab in eliminating residual hairy cells that remain after treatment by cladribine or pentostatin. It is not currently known if the elimination of such residual cells will result in more durable remissions.

The major remaining research questions are identifying the cause of HCL and determining what prevents hairy cells from maturing normally.