Despite the wide therapeutic potential of RNA interference (RNAi), clinical progress has been slow with only a few examples of successful translation. Efficient knockdown of hepatic transthyretin (87\%) in patients with transthyretin amyloidosis lasted for several weeks after a single dose. Furthermore, in a phase I clinical trial, a single dose of inclisiran (small interfering RNA (siRNA) against the PCSK9 mRNA) efficiently suppressed serum cholesterol for 6 months. However, these studies suggested that siRNA delivery beyond the liver is not yet feasible in the clinic and thus limits the potential benefit of RNAi.