High-Grade Salivary-Gland Involvement, Assessed by Histology or Ultrasonography, Is Associated with a Poor Response to a Single Rituximab Course in Primary Sjögren's Syndrome: Data from the TEARS Randomized Trial.

Purpose: To determine whether the severity of salivary-gland involvement, assessed using salivary gland ultrasonography [SGUS], histological focus score, or the unstimulated whole salivary flow [UWSF], was associated with the response to rituximab in patients with primary Sjögren's syndrome [pSS].
Materials and Methods: Among the 120 patients with pSS enrolled in the randomised TEARS trial of rituximab versus placebo, 35 underwent either centralised minor salivary-gland biopsy or SGUS at inclusion. The echostructure of each parotid and submandibular gland was graded on a scale of 0 to 4. Histologic minor salivary gland involvement was assessed by the focus score. Among rituximab-treated patients with available data (n = 14), half met the Sjögren's Syndrome Responder Index [SSRI]-30 definition of a response at week 24.
Results: The SGUS score correlated positively to the focus score [r = 0.61] and negatively to the UWSF [r = -0.68]. The focus score was not correlated to the UWSF. The median total SGUS grade at inclusion was 9 [6-11] in responders versus 16 [11-16] in non-responders [p = 0.04]. The proportion of SSRI-30 responders was 0% among patients with SGUS grade 4 and 88% among those with SGUS grade ≤3. Low baseline SGUS scores were associated with sicca-related outcomes improvement, but not with fatigue or biological improvement. Median baseline focus score was 0.3 [0.0-1.3] in the responders versus 4.0 [2.7-5.3] in the non-responders [p = 0.02]. Baseline UWSF was not associated with the response rate.
Conclusion: In patients with pSS, the highest SGUS grade or a high histological focus score is associated with absence of a response to a single rituximab course after 6 months. Further studies, including more patients and different treatment strategies, are required to confirm the clinical utility of these potential biomarkers in pSS.
Competing Interests: EH, VG, VDP, and AS have received consulting fees from Roche, less than 10 000 US$ each. This does not alter our adherence to PLOS ONE policies on sharing data and materials.