Conclusions Of Clinical Testing Of Bl22 In

BL22 is the first agent since purine analogs that can induce a CR in the majority of patients with HCL, and appears at least as active as rituximab for this disease. All patients treated with HCL had prior cladribine and had responded unsatisfactorily to at least the last course, and this includes patients with HCLv. Its success in chemoresistant patients is related to its different mechanism of action compared to purine analogs, and the fact that CD22 is highly conserved at high density on HCL cells despite purine analog resistance. Lack of CR was usually related to easily identifiable factors, including low doses due to the phase I design, and secondary immune response after cycle 1, which prevented effective retreatment. Patient 14 had signif icant splenomegaly which required several cycles to resolve, but disease in the marrow was still evident after cycle 12. In further follow-up, this patient was actually found to enter CR finally after cycle 14. The cause of HUS in patients receiving BL22 is not known, and since HUS has not been observed in over 100 patients receiving PE38 fused to ligands other than RFB4(dsFv), the mechanism must in part be mediated by CD22.

0 0

Post a comment