Background/Purpose:

Adalimumab (ADA) is currently approved in the EU for the treatment of severe non-radiographic axial spondyloarthritis (nr-axSpA), in patients (pts) with an elevated CRP and/or positive MRI who have had an inadequate response to, or are intolerant to NSAIDs. Reduction of sacroiliac joint (SIJ) and spine inflammation on MRI has been previously reported after 12 wks of ADA compared to placebo in the ABILITY-1 study. The objective of this analysis was to determine the efficacy of ADA in improving inflammation on MRI in pts with nr-axSpA and the relationship between MRI and clinical remission.

Methods:

ABILITY-1 is an ongoing phase 3, randomized, controlled trial in pts with nr-axSpA who had an inadequate response, intolerance, or contraindication to NSAIDs. A 12-wk double-blind period of ADA 40 mg every other week (eow) or placebo (PBO) was followed by an open-label period in which pts could receive ADA 40 mg eow for up to an additional 144 wks. MRI of the SIJ and spine were done at baseline (BL), wks 12, 52 and 104, and were read using the SPARCC scoring system (6 discovertebral unit method for the spine) by 2 independent readers who were blinded to time sequence. Mean reader scores were used. This post hoc analysis evaluated the efficacy of ADA in improving MRI inflammation at wks 52 and 104 in the overall population and in the MRI+/CRP+ subpopulation (pts who had positive BL MRI [SPARCC score ≥2 for either the SIJ or spine] or elevated BL CRP). Clinical remission was defined by ASDAS inactive disease (ASDAS ID, ASDAS <1.3) and MRI remission by SPARCC score <2.

 Results:

142 (69 ADA, 73 PBO) of the total efficacy population (N=185) were in the MRI+/CRP+ subpopulation. MRI obtained at wks 52 and 104 showed sustained mean improvements with long-term ADA therapy in SPARCC SIJ and spine scores for the overall population (wk 52 n=149, –3.7 and n=148, –1.2; wk 104 n=131, –3.8 and n=130, –1.4) and for the MRI+/CRP+ subpopulation (wk 52 n=116, –4.6 and n=115, –1.7; wk 104 n=102, –4.8 and n=101, –2.0). The table presents MRI and clinical remission rates among pts who had a positive MRI at BL (SPARCC score ≥2 for either the SIJ or spine).  Of the 46 pts who were in ASDAS ID at wk 104, 33 (72%), 35 (76%) and 26 (57%) had MRI remission of the SIJ, spine or both SIJ and spine respectively.

Table 2. Patients with baseline MRI Scores ≥2 for SI joint or Spine Achieving MRI and Clinical Remission at Weeks 52 and 104

ASDAS Inactive Disease Status	SPARCC SI Joint Score		SPARCC Spine Score		SPARCC SI Joint and Spine Scores
	<2 n	≥2 n	<2 n	≥2 n	SI Joint and Spine <2 n	SI Joint or Spine ≥2 n
Week 52	N=101
In ASDAS inactive disease	37	10	32	15	26	21
Not in ASDAS inactive disease	39	15	28	26	21	33
Week 104	N=88
In ASDAS inactive disease	33	13	35	11	26	20
Not in ASDAS inactive disease	33	9	19	23	18	24

N = patients who are MRI+ at baseline (MRI SPARCC score ≥2 for SI joint or spine) and with available ASDAS and MRI data. ASDAS, Ankylosing Spondylitis Disease Activity Score.

Conclusion:

In ABILITY-1, ADA therapy of up to 2 yrs in nr-axSpA pts resulted in reduction of inflammation on MRI. The majority of pts in clinical remission were noted to also have MRI remission. However, resolution or absence of inflammation on MRI did not always correspond to clinical remission.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/relationship-between-mri-and-clinical-remission-in-patients-with-non-radiographic-axial-spondyloarthritis-after-two-years-of-adalimumab-therapy/