Endocrine Abstracts

Background: Graves orbitopathy (GO) is the most frequent and feared complication of Graves’ disease. In moderate-severe cases, intravenous (iv) glucocorticoids (GC) is the first-line treatment while Rituximab (RTX) is recommended as second-line treatment in patients non-responsive to GC. But data is scarce and contradictory.

Objective: To investigate if patients with GO and poor response to iv GC benefit from a switch to RTX early in the treatment course.

Method: This was a non-randomized controlled interventional study of GO patients treated with iv GC for 4 weeks. Patients with < 2 points improvement in clinical activity score (CAS) after 4 weeks were selected for RTX treatment (the non-responders (NR-RTX) group). They were compared to patients who had improved at least 2 in CAS at 4 weeks and who continued with a full treatment period of iv GC for 12 weeks (the responders (R-GC) group). A retrospective group of patients who were non-responders at 4 weeks and who were provided regular care with 12 weeks (w) of iv GC was used as control (the NR-GC group). Baseline data and CAS at baseline, 4w, 12w, 18w and 68w were collected in all groups. Quality of life (QoL) and safety data were collected from NR-RTX and R-GC groups at the same time points.

Results: Baseline characteristics of NR-RTX (n =10) were similar to the other two groups, except for 1 point lower median CAS than NR-GC (n =12) (P = 0.03). The NR-RTX group had twice as many men compared to the R-GC group(n =13) (P = 0.03). No group differences were observed in CAS, in QoL or in safety data at any timepoint with the exception of a higher CAS in NR-RTX group at 4w and 12w compared to R-GC (P=0.005 and P=0.017 respectively), as expected given that CAS at 4w was the factor that determined the group selection. Longitudinal analyses revealed no differences in CAS, except for an increase between 4w and 18w in the R-GC group and a decrease between 4w and 68w in the NR-RTX group.

Conclusions: We could not confirm the hypothesis that a switch to RTX in GO patients with a poor response to 4w of iv GC is more effective or safer than conventional GO treatment. This is of clinical importance, as RTX is recommended by international thyroid associations as second line treatment for GO and previous research has presented contradictory results.