Background/Purpose:

Quality of life and functionality are important outcome metrics in understanding the value of therapeutic interventions in RA. Biological products have become an established therapeutic modality in rheumatic conditions and the development of biosimilar products that offer therapeutic equivalence are in development. One such biologic treatment in clinical development currently approved in Korea is a biosimilar monoclonal antibody to infliximab which has been in clinical use for the treatment of RA.

Methods:

As part of the development program for a biosimilar infliximab, in a phase 3, randomized, double-blind, active-controlled trial, 606 patients with RA were treated for up to 1 year with either biosimilar infliximab (CT-P13) or Originator infliximab (INX).  Treatment was initiated with 3mg/kg doses infused IV over 2 hours at Week 0, Week 2, Week 6 and then every 8 weeks up to Week 54. The primary endpoint (ACR20) previously reported, achieved therapeutic equivalence. Key secondary endpoints were captured; one such endpoint evaluated quality of life based on the standard HAQ-disability index and SF-36. The HAQ assessment of physical function measures 20 items in eight categories on a scale from 0 (without any difficulty) to 3 (unable to do). SF-36 assesses eight subscales, a low score representing poor health status. Baseline measurement was determined at the initiation of treatment and on treatment at Week 14, Week 30 and Week 54.

Results:

Adjusted HAQ and SF-36 outcomes in study patients with RA (mean ± standard deviation; per protocol population) are shown below in Table 1 and Table 2 respectively.

Table 1: Adjusted HAQ Outcomes

Index	Baseline			Week 14		Week 30		Week 54
	CT-P13 (n=246)		INX (n=250)	CT-P13 (n=246)	INX (n=250)	CT-P13 (n=246)	INX (n=250)	CT-P13 (n=226)	INX (n=220)
Overall HAQ	1.60+ 0.56		1.53+ 0.58	1.02+ 0.61	1.04+ 0.64	1.00+ 0.65	1.03+ 0.66	0.99+ 0.61	1.02+ 0.64
P-value	0.183			0.674		0.679		0.657
Components of the adjusted HAQ
Dressing and Grooming		1.52+ 0.72	1.42+ 0.76	0.87+ 0.84	0.87+ 0.82	0.85+ 0.83	0.88+ 0.82	0.88+ 0.83	0.93+ 0.82
Arising		1.37+ 0.77	1.29+ 0.78	0.76+ 0.74	0.82+ 0.77	0.82+ 0.75	0.89+ 0.79	0.79+ 0.74	0.83+ 0.74
Eating		1.58+ 0.80	1.52+ 0.83	0.95+ 0.75	0.90+ 0.80	0.90+ 0.77	0.92+ 0.81	0.84+ 0.76	0.90+ 0.82
Walking		1.28+ 0.75	1.28+ 0.75	0.82+ 0.80	0.82+ 0.79	0.84+ 0.81	0.78+ 0.82	0.77+ 0.79	0.79+ 0.78
Hygiene		1.69+ 0.83	1.59+ 0.85	1.11+ 0.97	1.21+ 0.93	1.14+ 0.96	1.19+ 0.92	1.14+ 0.94	1.20+ 0.90
Reach		1.89+ 0.69	1.77+ 0.78	1.24+ 0.81	1.31+ 0.84	1.15+ 0.86	1.20+ 0.87	1.17+ 0.81	1.15+ 0.83
Grip		1.79+ 0.71	1.73+ 0.74	1.16+ 0.85	1.21+ 0.87	1.18+ 0.88	1.16+ 0.91	1.13+ 0.88	1.13+ 0.90
Activities		1.71+ 0.76	1.66+ 0.78	1.20+ 0.81	1.17+ 0.83	1.16+ 0.83	1.20+ 0.82	1.21+ 0.76	1.20+ 0.82

Table 2: SF36 Outcomes

Index		Baseline		Week 14		Week 30		Week 54
		CT-P13 (n=246)	INX (n=250)	CT-P13 (n=246)	INX (n=250)	CT-P13 (n=246)	INX (n=250)	CT-P13 (n=226)	INX (n=220)
Physical Component Summary		31.44+ 6.08	31.84+ 7.21	38.94+ 7.61	37.64+ 7.94	38.66+ 7.88	38.34+ 8.00	39.22+ 7.52	38.57+ 8.71
P-value		0.5085		0.0641		0.6572		0.4036
Mental Component Summary		36.80+ 10.44	38.41+ 11.29	43.44+ 10.76	44.88+ 9.66	43.89+ 10.12	45.01+ 10.32	43.93+ 9.90	45.09+ 10.02
P-value		0.1005		0.1172		0.2218		0.2200
Scales of the SF-36
Physical Function	29.48+ 8.76		30.39+ 9.23	36.91+ 10.03	36.30+ 9.64	37.11+ 10.20	37.26+ 10.21	37.55+ 9.92	37.07+ 10.93
Role-Physical	31.69+ 7.87		32.29+ 8.18	38.45+ 8.67	38.12+ 8.69	38.56+ 8.87	39.19+ 8.88	39.19+ 8.47	39.42+ 9.17
Bodily Pain	31.39+ 5.78		32.81+ 7.03	41.55+ 8.14	40.96+ 8.11	40.85+ 8.59	41.08+ 8.52	41.06+ 8.14	40.95+ 8.89
General Health	33.44+ 7.53		33.00+ 7.89	38.95+ 8.94	37.99+ 8.29	38.94+ 8.75	38.26+ 8.33	39.52+ 8.49	38.76+ 8.68
Vitality	39.76+ 8.70		41.08+ 9.24	47.46+ 9.51	47.62+ 8.71	47.12+ 8.78	47.68+ 9.02	47.37+ 8.64	48.12+ 8.74
Social Functioning	32.86+ 9.57		34.18+ 10.18	40.82+ 9.81	40.99+ 10.07	41.35+ 10.02	41.21+ 9.78	41.50+ 9.36	42.17+ 10.18
Role-Emotional	30.32+ 11.51		31.73+ 11.99	37.52+ 11.79	38.29+ 11.12	38.14+ 11.57	38.79+ 11.23	38.20+ 10.90	38.55+ 11.39
Mental Health	36.36+ 10.23		37.76+ 10.91	42.78+ 10.74	44.37+ 10.00	43.01+ 10.56	44.78+ 10.03	43.26+ 10.00	44.38+ 10.05

Baselines were similar between treatment groups. Scores between 1 and 2 generally represent moderate to severe disability reflected in this population. Early overall improvement as measured by a reduction in the HAQ scores was evident and similar in magnitude between biosimilar infliximab and originator infliximab by Week 14. Changes over time were similar between the two treatments.  Effectiveness of CT-P13 and INX was sustained over the 1 year interval. The agents were generally well tolerated in RA patients in this study. In addition, there were clear correlations between HAQ and physical or mental component summary of SF-36 from Pearson’s test.

Conclusion:

Treatment with infliximab improved physical function as assessed by HAQ in patients with moderate to severe physical disability which was sustained over a one year interval. These data support the comparability with respect to improvement in physical function of CT-P13 and INX in patients with active RA.

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