- BL22
BL22, also called CAT-3888 or GCR-3888, is an
immunotoxin which attaches to and, upon internalization, killsB cell s. It has completed aPhase I clinical (human) trial and is currently in aPhase II clinical trial for the treatment ofhairy cell leukemia at a Phase I clinical trial for pediatricacute lymphoblastic leukemia andnon-Hodgkin's lymphoma [http://clinicaltrials.gov/ct/show/NCT00077493?order=2] at theNIH in the U.S. It may be useful against any B cellleukemia orlymphoma .Technically, BL22 is an anti-CD22 immunotoxin fusion protein between a murine anti-CD22 disulfide-linked Fv (dsFv) antibody fragment and an edited copy of bacterial Pseudomonas exotoxin PE38. The toxin is activated intracellularly, by the low
pH of thelysosome into which the entire protein was internalized via the CD22 receptor. The toxin kills the targeted cell throughribosome inactivation. [http://www.biospace.com/news_print.aspx?NewsEntityId=1132]BL22 is very similar to the newer
HA22 , which changes one amino acid in the antibody fragment to increase the binding affinity for the target molecule. Both of these proteins are designed to bind to theCD22 receptor on the surface of B cells.Business History
BL22 was initially designed and produced at the U.S.
National Cancer Institute , one of the agencies which make up theNIH . Early development of BL22 was funded by California biotechGenencor . [http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/11-01-2005/0004204747&EDATE=] The future drug was acquired byCambridge Antibody Technology at the end of 2005; less than a year later, CAT was purchased by British pharmaceutical companyAstraZeneca . [http://www.astrazeneca.com/pressrelease/5266.aspx]
Wikimedia Foundation. 2010.