Tocilizumab Shows Promising Benefits in Glucocorticoid-Resistant Thyroid Eye Disease

Overview

Thyroid eye disease (TED), also called Graves’ orbitopathy, is an autoimmune condition that affects the tissues around the eyes. It can cause redness, swelling, pain, bulging eyes, double vision, and, in severe cases, vision-threatening complications. The disease is most often linked to Graves’ disease, but it may persist or worsen even when thyroid hormone levels are treated.

Active, moderate-to-severe TED is usually treated first with intravenous glucocorticoids, which can reduce inflammation. However, a substantial number of patients do not respond adequately, and some relapse after treatment. For this glucocorticoid-resistant group, clinicians often need another option.

Tocilizumab is a monoclonal antibody that blocks the interleukin-6 receptor, reducing inflammatory signaling. Because inflammation plays a central role in TED, researchers have explored whether tocilizumab could help patients whose disease remains active despite steroid therapy. This prospective study evaluated that question in two independent real-world cohorts.

Why this study matters

TED is not only a cosmetic problem. When inflammation in the orbit becomes severe, the eyes can protrude, eyelids may not close properly, eye movements may become restricted, and double vision can interfere with daily life. The condition can also have a major emotional and social impact.

Current treatment options are improving, but there is still a clear need for effective second-line therapies, especially for patients who do not improve enough with glucocorticoids. A therapy that can reduce inflammation, improve eye symptoms, and remain reasonably safe would fill an important gap in care.

This study is important because it did not test tocilizumab in a small, isolated group. Instead, it followed patients prospectively at two tertiary referral centers in Poland and Serbia, giving a more practical view of how the drug performs in routine specialist practice.

How the study was done

The investigators conducted an open-label, prospective study from May 2022 to May 2025 at two thyroid eye disease referral centers: Warsaw, Poland, and Belgrade, Serbia. Adults with active, moderate-to-severe TED that had not responded adequately to intravenous glucocorticoids were enrolled.

All patients received tocilizumab at a dose of 8 mg/kg by intravenous infusion every 4 weeks for four cycles. They were followed for 24 weeks.

The study focused on two primary outcomes:
1. Improvement in a composite ophthalmic score, which reflects multiple aspects of eye disease activity and severity.
2. Improvement in disease-specific quality of life, measured with the Graves’ ophthalmopathy quality of life questionnaire (GO-QoL).

Secondary outcomes included changes in:
– Clinical activity score (CAS), a standard measure of inflammation in TED
– Proptosis, or forward bulging of the eye
– Eyelid aperture, the opening between the eyelids
– Diplopia, or double vision
– Thyrotropin receptor antibody (TRAb) levels, an autoimmune marker related to Graves’ disease
– Safety and adverse events

The study was registered at ClinicalTrials.gov as NCT06367517.

What the researchers found

A total of 44 patients were treated with tocilizumab: 32 in Warsaw and 12 in Belgrade.

Both primary endpoints were achieved in a large proportion of patients. In Warsaw, 20 of 32 patients (62.5%) improved in both the composite ophthalmic score and quality-of-life measures. In Belgrade, all 12 of 12 patients (100%) met both primary endpoints.

Several important clinical improvements were also observed:
– A reduction in CAS by at least 2 points occurred in 24 of 32 patients (75%) in Warsaw and 12 of 12 patients (100%) in Belgrade.
– Proptosis improved by at least 2 mm in 19 of 32 patients (59.4%) in Warsaw and 7 of 12 patients (58.3%) in Belgrade.
– Diplopia improved by at least 1 grade on the Gorman scale in 7 of 32 patients (21.9%) in Warsaw and 6 of 12 patients (50%) in Belgrade.
– Eyelid aperture decreased by at least 2 mm in 11 of 32 patients (34.4%) in Warsaw and 8 of 12 patients (66.7%) in Belgrade.

The autoimmune activity marker TRAb also declined substantially. Median TRAb levels fell from 7.0 to 2.1 IU/L in Warsaw and from 4.7 to 2.0 IU/L in Belgrade.

Importantly, no patient experienced worsening of TED during treatment.

What these results mean clinically

The findings suggest that tocilizumab may be a useful second-line therapy for patients with active, moderate-to-severe TED who have not responded well to intravenous glucocorticoids. The improvements were not limited to laboratory values or a single symptom. They were seen across several clinically meaningful domains: inflammation, eye bulging, eyelid changes, double vision, and quality of life.

That combination matters. In TED, treatment success is not just about lowering an inflammatory score. Patients care about whether the eyes feel less irritated, whether the swelling improves, whether they can read or drive without double vision, and whether they can function more comfortably in everyday life. The study suggests tocilizumab may help in all of these areas for at least a subset of patients.

The drop in TRAb levels is also notable. Although TRAb is not the only driver of TED, it reflects underlying autoimmune activity in Graves’ disease. A reduction in this marker supports the idea that IL-6 blockade may influence the disease process, not just the visible symptoms.

Safety profile

Safety is a major concern when adding immunomodulatory therapy. In this study, adverse events occurred in 18 of 44 patients, representing 40.9% of the cohort, with 47 events reported in total. Only one event was classified as severe.

The abstract does not provide a full breakdown of each adverse event, but the overall safety profile was described as generally acceptable. That is encouraging, especially in a population that often already has significant disease burden and may have previously received glucocorticoids.

As with all biologic therapies, tocilizumab requires careful monitoring. Clinicians typically watch for infection, liver enzyme abnormalities, blood count changes, and lipid changes. Patients should also be evaluated for any signs of treatment-related complications during follow-up.

Strengths and limitations

This study has several strengths. It was prospective, included two independent tertiary-center cohorts, and focused on patients who are often difficult to manage in routine practice. The outcomes were clinically relevant and included both disease activity and patient-reported quality of life.

However, there are also important limitations:
– The study was open-label, meaning both physicians and patients knew the treatment being given.
– There was no placebo or comparator group.
– The sample size was relatively small, especially in the Belgrade cohort.
– Follow-up was limited to 24 weeks, so longer-term durability of response remains uncertain.

Because of these limitations, the study cannot prove that tocilizumab is superior to all other strategies, but it does provide meaningful real-world evidence that the drug can be effective in a difficult-to-treat population.

How this fits into current TED care

The standard management of TED depends on disease activity and severity. Mild disease may be managed with local measures, thyroid control, selenium in selected cases, and observation. Active, moderate-to-severe disease often requires systemic therapy, historically with intravenous glucocorticoids.

For patients who do not respond well enough to steroids, newer targeted therapies have expanded the treatment landscape. Tocilizumab works by blocking interleukin-6 signaling, which may help reduce orbital inflammation. In practice, this could make it a useful option for patients whose disease remains active despite standard therapy or in whom repeated glucocorticoid exposure is undesirable.

The results of this study support the idea that IL-6 inhibition is a plausible and potentially effective approach. Still, treatment decisions should be individualized, taking into account disease activity, smoking status, thyroid control, comorbidities, prior therapies, and the patient’s risk tolerance.

Bottom line

In this prospective real-world study of 44 patients with active, moderate-to-severe, glucocorticoid-resistant thyroid eye disease, tocilizumab was associated with meaningful improvements in inflammation, proptosis, diplopia, eyelid aperture, quality of life, and TRAb levels. No patient worsened during treatment, and the overall safety profile was acceptable.

These findings support tocilizumab as a promising second-line option for selected patients with difficult-to-treat TED. Larger controlled studies will be important to confirm how well it works, which patients benefit most, and how it compares with other modern therapies.