Table 2.

Results for the analysis of each IC, expressed as a range for number of lots evaluated^a.

		Brand name (no. of batches tested)
Method (parameter)	Enbrel® specification	Yisaipu (n = 5)	Etanar® (n = 5)	Etacept (n = 6)	Infinitam (n = 3)	Altebrel™ (n = 1)	Qiangke (n = 2)	Intacept (n = 3)
Peptide map (identity)	Profile	Comparable	Comparable	Comparable	Comparable	Not comparableb	Not comparableb	Not comparableb
Hydrophobic interaction	Peak 1: ≤5%c	0	0	0–2	3–4	3	0	1–2
chromatography (purity)	Peak 2: ≥70%c	99–100	99–100	88–100	82–95	81	100	80–87
	Peak 3: ≤28%c	0	0	0–10	2–13	16	0	12–19
	Profile	Not comparabled	Not comparabled	Not comparabled	Comparable	Comparable	Not comparabled	Not comparable
Size exclusion HPLC (purity)	Peak A+A’: ≥94.0%c	91.8–95.7	91.0–97.7	92.3–95.5	97.6–98.8	95.9	95.3–96.3	98.3–98.5
	Peak B: ≤6.0%c	4.3–8.2e	2.3–9.0e	4.5–7.6e	1.2–2.4	4.1	3.7–4.7	1.5–1.7
	Profile	Comparable	Comparable	Comparable	Comparable	Comparable	Comparable	Comparable
N-linked oligosaccharide map	Neutral %c	50–59	52–58	47–56	69–74	87	79–86	69–72
(quality)	Sialylated %c	41–50	42–48	44–53	26–31	13	13–21	28–31
	Profile	Comparable	Comparable	Comparable	Not comparablef	Not comparablef	Not comparablef	Not comparablef
HCP ELISA (purity)	≤60 ppm	23–61g	40–105g	17–66g	ND	32	ND	1
Protein A ELISA (purity)	≤40 ppm	2–5	2–52h	1–3	ND–1	28	5–13	<1
Charge distribution IEF & AEX (characterization)	N/A	Less negatively chargedi	Less negatively chargedi	Less negatively chargedi	Similar charge distribution	Less negatively chargedj	Less negatively chargedi	Less negatively chargedj
SDS-PAGE Coomassie scanning	Monomer ≥88%	92–94	91–94	92–95	90–97	93	92–95	95–96
densitometry	HMW component ≤6%	3–5	3–5	3–5	2–4	3	3–6	2
	LMW component ≤8%	2–3	2–5	1–3	1–6	5	2	2–3
Sialic acid content	70–130% of RS	78–92	76–89	63–91	91–105	84	70–79	75–76
Receptor binding (TNF by ELISA)	70–150 BU	112–128	81–91	92–121	98–138	100	124–135	109–144
U937 cell-based potency (inhibition of TNF-induced apoptosis)	1.0–2.9 × 106 U/mg (IU)	1.7–2.1	1.5–1.9	1.7–2.2	1.7–1.9	1.4	1.9–2.1	1.5–1.8

^aResults outside the specified range are indicated in bold;

^bpresence of additional peaks, and absence of expected peaks compared with Enbrel® RS (Fig. 1);

^crelative % peak area;

^datypical profile (Peak 1 [clips] and Peak 3 [aggregate] not detected) but species known to be present by orthogonal testing;

^ebatches (Yisaipu [n = 3]; Etanar® [n = 3]; Etacept [n = 3]) failed release specification (levels of aggregate exceeded);

^fatypical profile (presence of new glycan species identified (Fig. 2C) and reduced content of sialylated N-linked oligosaccharides);

^gabove specification for HCP (Yisaipu [1/5], Etanar® [4/5], Etacept [1/6];

^habove specification for residual protein A (Etanar® [2/5]);

ⁱdue to greater abundance of more neutrally charged species;

^jdue to fewer negatively charged species. BU, binding units; ELISA, enzyme-linked immunosorbent assay; HCP, host-cell protein; HMW, high molecular weight; HPLC, high-performance liquid chromatography; IC, intended copy; LMW, low molecular weight; N/A, not applicable; ND, not detected; RS, reference standard; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TNF, tumor necrosis factor.