Tumor necrosis factor inhibitors reduce both spinal and sacroiliac radiographic progression in early axial spondyloarthritis (axSpA), but the effects take time.
Dr. Denis Poddubnyy
According to data from the German Spondyloarthritis Inception Cohort (GESPIC), it could take 2-4 years after the initiation of TNF inhibitor treatment before x-rays will show any sign of a benefit in either the spine or sacroiliac joints (SIJ).
“The association between anti-TNF treatment and the retardation of radiographic spinal progression in spondyloarthritis appears to be time-shifted,” GESPIC study investigator Denis Poddubnyy, MD, said at the annual European Congress of Rheumatology.
Reporting the spinal findings, Dr. Poddubnyy, who is head of the rheumatology department at Campus Benjamin Franklin of the Charité University Hospital in Berlin noted that “at least 4 years of observation is required” to see an effect of TNF inhibitors on new bone formation. “This might be related to the intermediate and long-lasting process of bone repair that follows the resolution of inflammation and precedes the development of new bone,” he suggested.
The effect on the SIJ may precede the spinal damage, so it’s important to look at how anti-inflammatory treatment might affect the SIJ, Dr. Poddubnyy said in an interview. Results from the SIJ analysis, which were presented by Murat Torgutalp, MD, suggested that there might be a 2-year time lag between TNFi treatment and being able to see something on x-rays.
Dr. Murat Torgutalp
“Everybody in the past focused on the spine, considering that spinal changes are functionally more relevant than changes in the SIJ,” Dr. Poddubnyy observed.
Structural damage in the spine and SIJ in radiographic axSpA probably occur by different processes, he explained. While it’s more to do with new bone formation in the spine, it’s more to do with erosive damage followed by repair in the SIJ. “It is very likely that in the majority of patients we see that those two processes are somehow disconnected in time,” he suggested.
The GESPIC cohort provides a good base from which to examine the effects of TNF inhibitors on radiographic progression in patients with axSpA for several reasons, observed Dr. Poddubnyy. For one it was established in 2000, so “well before the introduction of TNF-alpha inhibitors.” That means that almost all patients would have been put on TNF inhibitors while enrolled in the cohort, he said, “so we could really follow up them prospectively for a few years.” In fact, just nine patients had been treated with TNF inhibitors at baseline.
Spinal findings
Although TNF inhibitors are widely accepted to be effective anti-inflammatory drugs that can relieve patients’ spinal symptoms, there were inconclusive data on whether they can also have an impact on radiographic progression.
To look at the possible immediate or later effect of TNF inhibitors on spinal radiographic progression, the GESPIC investigators looked at sets of radiographs, taken at least 2 years apart over a 10-year period, from 266 patients, 77 of whom who had been treated with a TNF inhibitor for at least 12 months or more. Overall, there were 103 2-year intervals covered by TNF inhibitor treatment of any duration, and 78 intervals in which treatment had lasted for at least 12 months.
“This cohort included patients with quite early disease, including both nonradiographic and radiographic forms,” Dr. Poddubnyy said, adding that some patients had been treated with a TNF inhibitor for up to 10 years.
While there were no significant changes in radiographic progression as measured using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) between patients who had and who had not received at least 12 months’ TNF inhibitor therapy in the first 2 years, there was a substantial difference after 4 years.
The mSASSS change in scores over 2 years in patients who were and were not treated with a TNF inhibitor for 12 months or more were a respective 0.35 and 0.81 (P = .047) considering treatment in the previous 2-year treatment period, and 0.33 and 0.77 (also P = .047) considering treatment in the prior 2-year treatment period and the current 2-year period.
“Our interpretation is that within the first 2 years we see a resolution of inflammation, a process of repair, maybe even a process of bone formation, but then if you continue this inflammation control for longer than 2 years, then we see the effect on structural damage,” Dr. Poddubnyy said.