Verve Therapeutics - The best I've heard is that this company (a few years ago and still ongoing) began trying to create a permanent, one-off treatment for FH using gene technology:
"Verve is developing a single-dose base-editing treatment for heterozygous familial hypercholesterolemia (HeFH)... the only in vivo base-editing candidate... specifically designed to permanently switch off the PCSK9 gene in the liver, to durably lower disease-driving low-density LDL-C. "