ASPG and homocystinuria: Additional novel PEGylated enzymes in clinical trials and their investigated indications include hyaluronidase (cancer), human cystathionine β‐synthase (homocystinuria), urate oxidase (hyperuricemia), cobalt‐substituted arginase (Hyperargininemia), Erwinia asparaginase (leukemia) and cystathionine γ‐lyase (homocystinuria).