Biologic activity and safety of belimumab, a neutralizing anti-B-lymphocyte stimulator (BLyS) monoclonal antibody: a phase I trial in patients with systemic lupus erythematosus

Table 4 Summary of grade 3 and 4 laboratory and hematologic toxicities

Parameter	Grade	Placebo (n = 13)	Belimumab
			1.0 mg/kg (n = 15)	4.0 mg/kg (n = 14)	10 mg/kg (n = 14)	20 mg/kg (n = 14)	All active (n = 57)
Activated partial thromboplastin time	3	0	0	1 (7)	0	1 (7)	2 (4)
Creatinine	3	0	0	0	0	1 (7)^a	1 (2)
Hemoglobin	3	0	1 (7)	0	0	0	1 (2)
Hyperglycemia	3	0	1 (7)		0	0	1 (2)
Neutropenia	3	0	0	1 (7)^b	2 (14)	0	3 (5)
Thrombocytopenia	4	0	0	1 (7)^b	0	0	1 (2)
Proteinuria	3	0	0	0	1 (7)	1 (7)^a	2 (4)
	4	0	0	0	0	1 (7)	1 (2)
Prothrombin time	3	3 (23)^c	1 (7)^c	0	0	0	1 (2)
	4	2 (15)^c	0	0	0	0	0

Values are expressed as n (%). ^aOne patient had grade 3 serum creatinine and grade 3 proteinuria. ^bOne patient with grade 3 neutropenia and grade 4 thrombocytopenia after the first 10-mg/kg dose was rechallenged at grade 1 neutropenia, without further decline after the second dose. ^cFour of six patients with grade 3 or 4 prothrombin time reported concomitant warfarin use, including the two patients with grade 4 prothrombin time.

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