Complex sentence: They act by binding the active site of the mutant "IDH1" enzyme and prevent binding of the substrate alpha-ketoglutarate, this prevents the enzyme from forming D2-HG and leads to a reduction in D2-HG levels.
Split into simpler sentences: They act by binding the active site of the mutant "IDH1" enzyme and prevent binding of the substrate alpha-ketoglutarate. This prevents the enzyme from forming D2-HG and leads to a reduction in D2-HG levels.