Table 3.

siRNA plasma protein binding reported in regulatory filings up until 2020

	Patisirana	Givosirana	Lumasirana	Inclisirana
Species tested	unknown	mouse, rat, monkey, human	mouse, rat, monkey, human	mouse, rat, monkey, human
Cmax (human therapeutic dose)	7050 ng/ml (0.3 mg for patients < 100 kg, 30 mg for patients > 100 kg by i.v. infusion)	321 ng/ml (2.5 mg/kg by s.c. injection)	701 ng/ml (3–6 mg/kg (based on body weight) with loading doses by s.c. injection)	507 ng/ml (284 mg initially, at 3 months, then every 6 months thereafter)
Delivery vehicle	LNP	GalNAc conjugate	GalNAc conjugate	GalNAc conjugate
Concentration tested	unknown	0.5–50 μg/ml (EMA) 1–50 μg /ml (FDA)	0.5–50 μg/ml (EMA) 5–100 μg/ml (FDA)	0.5 μg/ml (human Cmax)
PPB (across concentrations tested)	∼97%b	10–91% (mouse) 28–93% (rat) 26–90% (monkey) 21–92% (human)	35–96% (rat) 37–86% (monkey) 20–85% (human) (EMA) FDAd	87% (human) < (mouse, monkey) < 93% (rat)
Human PPB at clinically relevant concentrations		92% at 1 μg/ml	77–85% at 0.5–1 μg/ml	87% at 0.5 μg/ml
Specific siRNA-plasma protein interactions	Rat serum albumin – 0.89%c Human serum albumin – 0.46%c Human a1-acid-glycoprotein – 2.1%c
Method	PPB – not reported Specific plasma protein interactions – FPLC followed by SDS-PAGE	EMSA	EMSA	Not reported

Abbreviations: C_max, maximum concentration in plasma; EMA, European Medicine Agency; EMSA, electrophoretic mobility shift assay; FDA, Food and Drug Administration; GalNAc, N-acetylgalactosamine; LNP, lipid nanoparticle; PPB, plasma protein binding.

^aPatisiran, givosiran and lumasiran data are from combined FDA and EMA approval documents. Inclisiran data is from EMA approval document. All PPB values reported here have been rounded to two significant figures.

^bReflects binding of the lipid excipient only (no siRNA) to human plasma.

^cReflects binding of intact LNP to rat serum albumin, human serum albumin and human alpha-1-acid glycoprotein separately.

^dEMA results should be used for this assay after discussion with Alnylam.