Enzyme enhancers for the treatment of Fabry and Pompe disease

Lysosomal storage disorders (LSD) are a group of heterogeneous diseases caused by compromised enzyme function leading to multiple organ failure. Therapeutic approaches involve enzyme replacement (ERT), which is effective for a substantial fraction of patients. However, there are still concerns about a number of issues including tissue penetrance, generation of host antibodies against the therapeutic enzyme, and financial aspects, which render this therapy suboptimal for many cases. Treatment with pharmacological chaperones (PC) was recognized as a possible alternative to ERT, because a great number of mutations do not completely abolish enzyme function, but rather trigger degradation in the endoplasmic reticulum. The theory behind PC is that they can stabilize enzymes with remaining function, avoid degradation and thereby ameliorate disease symptoms. We tested several compounds in order to identify novel small molecules that prevent premature degradation of the mutant lysosomal enzymes α-galactosidase A (for Fabry disease (FD)) and acid α-glucosidase (GAA) (for Pompe disease (PD)). We discovered that the expectorant Ambroxol when used in conjunction with known PC resulted in a significant enhancement of mutant α-galactosidase A and GAA activities. Rosiglitazone was effective on α-galactosidase A either as a monotherapy or when administered in combination with the PC 1-deoxygalactonojirimycin. We therefore propose both drugs as potential enhancers of pharmacological chaperones in FD and PD to improve current treatment strategies.