Abstract: SA-PO196
Monoclonal Gammopathy of Renal Significance (MGRS) Without Detectable Clones: Clinical Treatment Dilemma
Session Information
- Onconephrology: Immunological Cross-Talk
November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1700 Onconephrology
Authors
- Terashita, Maho, Brigham and Women's Hospital, Boston, Massachusetts, United States
- Selamet, Umut, Dana-Farber Cancer Institute, Boston, Massachusetts, United States
- Midha, Shonali, Dana-Farber Cancer Institute, Boston, Massachusetts, United States
- Nadeem, Omar, Dana-Farber Cancer Institute, Boston, Massachusetts, United States
- Laubach, Jacob, Dana-Farber Cancer Institute, Boston, Massachusetts, United States
- Rennke, Helmut G., Brigham and Women's Hospital, Boston, Massachusetts, United States
- Murakami, Naoka, Brigham and Women's Hospital, Boston, Massachusetts, United States
Background
Monoclonal gammopathy of renal significance (MGRS) is characterized by monoclonal immunoglobulin deposition in kidneys. However, monoclonal immunoglobulin is not always detectable in blood, urine, or bone marrow (BM). Treatment response and kidney outcome of MGRS without a detectable clone remains unclear.
Methods
In this single-center, retrospective cohort study, we identified 192 cases of monoclonal immunoglobulin deposition disease (MIDD) from our biopsy repository between 2010 to 2022, of which 86 had follow-up at our center. Inclusion criteria were: (1) negative serum protein electrophoresis and immunofixation, (2) normal serum free light chain ratio adjusted for kidney function, (3) no clone identified in BM, and (4) no specific hematologic diagnosis. We analyzed the best kidney response by therapies (no therapy, plasma cell (PC)-targeted vs. non PC-targeted targeted therapy). Those with at least one PC-targeted treatment were classified as the PC-targeted group.
Results
We included 26 native kidney and 2 transplanted kidney biopsies in this analysis. The median age was 58 (IQR 47-66) and 54% were male. The most frequent subtype of monoclonal immunoglobulin deposited in the kidneys was IgG3 kappa. 67% of patients who had proteinuria >1.0 g/gCr at diagnosis achieved complete response (CR)/ partial response (PR) regardless of the treatment regimen (Figure). Lower proportion of patients achieved CR if they had >50% interstitial fibrosis tubular atrophy (IFTA) at diagnosis. Two cases of MGRS in transplanted kidneys did not respond to treatment. Six out of 7 re-biopsies showed IFTA progression.
Conclusion
Treatments and outcomes of MGRS without a detectable clone were extremely variable. Re-biopsy provided limited information to assess disease activity or the need for additional treatment. More sensitive tools are needed to detect clones and to assess treatment response.