Rituximab May Ease Arthritis in Longtime SSc, Small Study Finds

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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The immunosuppressant Rituximab may ease arthritis — an inflammation of the joints — in patients with long-standing systemic sclerosis (SSc), a small Turkish study found.

Moreover, in some patients, skin and lung symptoms either remained stable or eased, the researchers also observed.

“The factors and markers affecting the treatment response in rituximab responders may be the subject of new studies,” the investigators wrote, noting both that the therapy “appears to be effective in SSc-associated arthritis” and that “the success rate of [Rituximab] seems to be higher in the mild severity/extent of lung involvement and early stage of skin involvement.”

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The study, “Rituximab on lung, skin, and joint involvement in patients with systemic sclerosis: A case series study and review of the literature,” was published in the International Journal of Rheumatic Diseases.

Rituximab is a medication that decreases the number of B-cells, a type of immune cell, by causing their death. The medication is marketed as Rituxan in the U.S., and as MabThera in Europe, and also is available as a range of biosimilars.

Its use is approved for certain blood cancers and autoimmune diseases in which the immune system turns against the body’s own cells, attacking them and causing inflammation. One such disease is rheumatoid arthritis, an inflammation that causes swelling, pain, and damage to the joints, most commonly including those of the hands and feet.

In some cases, rituximab has been used off-label to treat patients with lung damage from scleroderma. While some studies have looked at the effects of rituximab on skin and lung symptoms, less is known about its effects on arthritis in patients with SSc.

To learn more, researchers now drew on data from the medical records of eight patients — five women and three men — with SSc who were treated with rituximab.

Five patients had diffuse scleroderma, a subtype of the chronic disease that’s marked by extensive skin scarring over large areas of the body and damage to the internal organs. The remaining three patients had limited scleroderma, another subtype of scleroderma that is generally milder than the diffuse form.

The mean age of the patients was 62.4, and the mean disease duration was 16.7 years. All but one of the patients (seven, or 87.5%) were started on rituximab because they had treatment-resistant arthritis. The other patient (12.5%) had progressive skin symptoms.

Each received three cycles of rituximab, spaced every six months. The cycles each included an intravenous (into-the-vein) infusion of 1 gram of rituximab, followed by a second infusion 15 days later.

Methylprednisolone, a corticosteroid, was used prior to each infusion to prevent infusion-induced reactions, which are commonly reported among patients on such therapy. All of the individuals were allowed to continue with their usual medication regimens, including other immunosuppressants and corticosteroids.

Two patients with pulmonary arterial hypertension, which is caused by a narrowing of the blood vessels that supply the lungs, died after the first rituximab cycle. Both had sudden cardiac death, or loss of heart function.

Of the six patients who survived, five had arthritis. When the researchers watched for changes in disease activity between before and one year after rituximab treatment, they found it had significantly improved.

The median DAS28-CRP score — used to monitor disease activity and how well patients with arthritis are responding to treatment — decreased from 4.97 to 3.95 points. The median Clinical Disease Activity Index (CDAI), another measure of disease activity, decreased from 39 to 16 points.

Next, the researchers looked at skin thickening using the modified Rodnan Skin Score (mRSS). While the median mRSS did not improve significantly after rituximab treatment, among the five patients with diffuse scleroderma, mRSS did not worsen by more than five points. That’s minimal clinically significant difference reported for people with dcSSc. Moreover, in one patient, that score decreased by 10 points.

Five patients had interstitial lung disease, or lung disorders in which the tissue in and around the lung air sacs becomes inflamed and scarred. When the researchers watched for changes in forced vital capacity (FVC), a measure of lung function, they found that it had improved in two, worsened in one, and remained stable in two patients at one year after rituximab treatment.

“The effect of [rituximab] on lung and skin involvement was in favor of stabilization or improvement,” the researchers wrote. However, the median FVC did not improve significantly with rituximab treatment, nor did the diffusing capacity for carbon monoxide (DLCO). The DLCO is a measure of the ability of gas to transfer from the tiny airways to the red blood cells.

While the patients were few and used other immunosuppressants, the findings suggest that rituximab may be effective to treat arthritis in patients with SSc, the researchers concluded.