Characteristics of Light Chain Deposition Disease (LCDD) and Factors Affecting Outcome after Treatment

Introduction. LCDD is a plasma cell dyscrasia in which monoclonal immunoglobulin light chains are deposited in organs, principally kidneys. Frequently kidney biopsy confirms the diagnosis, but other organs may be involved. We hypothesize that pure LCDD has better prognosis than LCDD as part of multiple myeloma (MM). Methods. We conducted a retrospective study in which our goal was to describe the outcomes, hematologic and clinical, of LCDD patients treated at our center. We assessed level of hematologic response like in MM, and clinical response was measured by improvement in the end organ function. We also compared PFS and OS in pure LCDD cases versus LCDD as part of MM (LCDD/MM). Results. Ten patients with biopsy proven LCDD, including one with mixed LCDD and cast nephropathy, were evaluated (Table 1). The median age at presentation was 59 yrs. Four patients had LCDD and active multiple myeloma (MM) while 6 patients had pure LCDD. Two patients had chronic kidney disease (CKD) stage 3, 6 had CKD stage 4 and 2 had CKD stage 5 at diagnosis. Five patients needed renal replacement therapy (RRT) (2 peritoneal dialysis and 3 Hemodialysis). Five patients had heavy chains (all IgG kappa) and 5 had only kappa light chain disease. Urine immunofixation showed Kappa light chain in 5 patients, rest were negative. All patients were treated with standard therapy consisting of proteasome inhibitors (PI), either cyclophosphamide or Immunomodulators (IMiDs) and Steroids with 9 going on to receive an autologous stem cell transplant (ASCT). Median time to ASCT was 7 months after diagnosis (range 4-24). Nine patients reached VGPR or CR while one had PR. Two patients died, one with pure LCDD died due to dialysis related complications and one with LCDD/MM due to disease progression, 4 and 2 years after ASCT, respectively. Therapy led to a fall in creatinine from a mean of 4.984 to 3.29 mg/dL (p=0.383) and significant improvement in GFR from mean of 22.5 to 38.1 mg/ml (p=0.049). In subgroup analysis, improvement in creatinine, GFR, creatinine clearance and was not statistically significant in the patients with pure LCDD. In contrast, the group with LCDD and MM showed significant improvement in creatinine from 4.41 to 1.95 (p=0.0061), GFR from 17.25 to 37.25 (p=0.0001) and creatinine clearance from 18.75 to 3.65 (p=0.0022). In the pure LCDD group, 2 patients were on RRT before ASCT, and both continued to need RRT post-Transplant. In the LCDD/MM , 2 patients needed RRT before ASCT and one could get off Dialysis after ASCT. None of the patients who had hematologic VGPR/CR and clinical renal improvement have shown progression of LCDD. The median overall survival for both groups hasn't been reached after a median follow up of 5 years (range, 0.5 to 10 years). Conclusions. Our series, though small, provides hints into prognostic variables affecting outcomes in LCDD. Our study shows that patients with LCDD/MM had a greater improvement in kidney function in comparison to pure LCDD. On the other hand, LCDD/MM patients were more likely to have hematologic progression.

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