For patients with chemo-resistant leukemia, a new drug is showing promising results.For the past decade, researchers have been experimenting with bacteria-based recombinant immunotoxins. An immunotoxin is bioengineered and consists of only the most essential and functional part of the antibodies that are commonly used to fight leukemia. One of those immunotoxins, BL-22, is showing encouraging results in a phase II study.
Researchers say in a phase I study, 19 of 31 patients with hairy cell leukemia had a complete remission of the disease after treatment. Another six people had partial responses. Researchers say, even if patients did not have remissions, they usually had improvements in their blood count to a level that was nearly normal. This is significant because most hairy cell leukemia patients die from low blood counts.
Researchers say the goal of the phase II study is to determine the best dosage levels and they hope that that response rate [in phase II] will be higher since they are treating with a good dose in all the patients. In the first cycle, trial participants were given 40 micrograms/kilograms every other day for three doses. If patients needed repeated cycles, they were given 30 micrograms/kilograms every other day for three doses.
Researchers say the study showed positive results and many of the patients had complete remissions for a long time.