RE: Is it us...? It can't be, can it?29 May 2023 18:40
The key (haha!) part of the invention is the -D-Ala-L-Pro- link in the substrate that can be cleaved (hydrolysed, split with the addition of -OH and -H) by FAP. The leaving group is the bit that fits inside the FAP pocket and has to have certain characteristics that will fix the substrate in position, typically the forming of hydrogen bonds and electrostatic attraction. For example, a long hydrocarbon chain, -(CH2)n-CH3, would not do the job (wouldn't fit), nor would just a methyl group, -CH3 (loss of specificity).
It is the fit of the leaving group that makes the substrate specific for FAP which is why I do not understand why two versions are in play except that maybe both are equally good or each is better for the prodrug it is attached to. If there are other leaving groups, which other companies might try, the invention is protected because the key part is the -D-Ala-L-Pro- link.