Rituximab in Idiopathic Retroperitoneal Fibrosis

Veronika Boyeva¹, Hatim Alabsi², Michael Seidman³, Ryan Paterson⁴, Jason Kur⁵, Silvia Chang⁶, Luke Chen⁷ and Mollie Carruthers⁵, ¹Department of Medicine, University of British Columbia, Vancouver, BC, Canada, ²Department of Radiology, King Abdulaziz University, Jeddah, Saudi Arabia, ³Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada, ⁴Department of Urology, University of British Columbia, Vancouver, BC, Canada, ⁵Rheumatology, University of British Columbia, Vancouver, BC, Canada, ⁶Department of Radiology, University of British Columbia, Vancouver, BC, Canada, ⁷Department of Hematology, University of British Columbia, Vancouver, BC, Canada

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: IgG4 Related Disease, Retroperitoneal Fibrosing and rituximab

Session Information

Date: Sunday, October 21, 2018

Title: Miscellaneous Rheumatic and Inflammatory Diseases Poster I: Checkpoint Inhibitors, Retroperitoneal Fibrosis

Session Type: ACR Poster Session A

Session Time: 9:00AM-11:00AM

Background/Purpose:

Retroperitoneal fibrosis (RPF) is a rare disease characterized by the proliferation of fibrous tissue in the retroperitoneum, most commonly surrounding the aorta from the renal vessels to the branching of the iliac arteries. RPF has a number of etiologies, which include idiopathic, IgG4-related, infectious, malignant, and drug-induced. However, the majority of cases are of either idiopathic or IgG4-related disease. Recent studies on IgG4-related disease have shown rituximab to possibly be an effective treatment. However, the current first-line treatment for idiopathic RPF (iRPF) is glucocorticoid therapy. Relapse rates vary widely in the literature after discontinuation of treatment, and DMARDs remain poorly studied. We sought to evaluate the efficacy of rituximab in idiopathic RPF by quantifying changes in iRPF diameter on imaging pre- and post-rituximab therapy in ten iRPF patients as well as response by lab parameters.

Methods:

This study was approved by the ethics review board at the University of British Columbia. All except one patient had histopathologic proof of their idiopathic RPF diagnosis. All patients had clinical and imaging features consistent with the diagnosis. All patients were previously treated with rituximab (1000mg) in two doses approximately 2 weeks apart. Pre- and post-therapy contrast enhanced cross-sectional abdomen and pelvis imaging were compared, of which 17 were CTs and one was an MRI. In all patients, the thickest portion of the peri-aortic disease was measured in the axial plane. The presence of acute and/or long standing unilateral or bilateral back pressure related renal findings were also documented (e.g. hydronephrosis, presence of stents, and renal atrophy). Details of clinical visits including patient demographics, symptoms, biopsies and laboratory evaluations were also collected pre- and post-therapy. Statistical analysis was performed using a Student’s t-test. A probability of p<0.05 was considered statistically significant.

Results:

A comparison of pre and post-rituximab imaging studies were available in nine patients and revealed a statistically significant decrease in iRPF diameter following treatment with rituximab. The RPF diameter around the aorta before and after therapy decreased from a mean of 16.4 +/- 4.9 cm to 10.8 +/- 6.5 cm, respectively (p=0.016). The craniocaudal iRPF mean length decreased from 110.1 cm +/- 42.6 to 94.0 +/- 47.3 (p=0.027). The GFR increased from 62.1 +/- 13.1 to 64.8 +/- 15.6, the creatinine decreased from 108.9 umol/L +/- 17.1 to 105.4 +/- 20.2, and the CRP decreased from 15.7 mg/dl +/- 16.4 to 4.3 +/- 5.2 when comparing mean values before to after therapy, respectively, but non-significantly.

Conclusion:

There were statistically significant improvements in iRPF diameter following treatment with rituximab. Rituximab requires further study to establish its role in treating idiopathic RPF.

Disclosure: V. Boyeva, None; H. Alabsi, None; M. Seidman, None; R. Paterson, None; J. Kur, None; S. Chang, None; L. Chen, None; M. Carruthers, None.

To cite this abstract in AMA style:

Boyeva V, Alabsi H, Seidman M, Paterson R, Kur J, Chang S, Chen L, Carruthers M. Rituximab in Idiopathic Retroperitoneal Fibrosis [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 9). https://acrabstracts.org/abstract/rituximab-in-idiopathic-retroperitoneal-fibrosis/. Accessed .

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