Anaphylactoid reactions will be a major problem for a drug that is competing against established products without such problems. Old label, new label...makes no difference if this protein has elicited anaphylactoid reactions due to its immunogenicity.
This is for drug that FDA has approved, and is manufactured by Shire. Look at page 7 at the end, and you'll see that Hypersensitivity reactions was occurring also, in 2 patients. Read farther in the document and you'll see that hypersensitivity is something that can happens in over protein drug.