Another fascinating study at the ATC 2010 talked about the role of bortezomib in decreasing HLA
Bortezomib is a proteosomal inhibitor shown in small studies to have a pronounced effect on decreasing HLA-antibodies post transplantation. Previously it has been studied in patients with humoral rejection and coupled with other treatments including plasmapheresis, steroids, and rituximab. The mechanism of antibody reduction is depletion of long lived plasma cells which are very difficult to eradicate by conventional therapy. The abstracts presented in the ATC revealed Bortezomib to have some effect on both anti HLA antibodies and plasma cells pre-transplant; as a method of desensitization. Unfortunately neither abstracts revealed hard endpoints such as percentage of patients transplanted or comparison to a control group. In addition both studies had relatively small numbers and were single center studies. The most common side effect seems to be peripheral neuropathy however most cases were mild and at least partially reversible.
Conclusions/ Comments: Expert opinion seems to be that the optimal use and effect of bortezomib is currently unknown. It does have some effect on HLA antibodies but will not magically decrease PRA to 0%. It may also work better with concurrent plasmapheresis, as stimulated plasma cells are probably more susceptible to proteosomal inhibitor induced apoptosis. Large multicenter studies need to be performed in sensitized patients with bortezomib. Some type of control group needs to be employed and hard endpoints (transplantation) will be needed. The use of proteosomal inhibitors at this time should remain in a properly conducted study.
by Vinay Nair