Plasma exchange in myeloma-associated acute kidney injury: A multicenter propensity-matched cohort study.

Abstract

7575 Background: Acute kidney injury (AKI) in newly diagnosed multiple myeloma (MM) is frequently driven by light chain cast nephropathy and associated with dialysis dependence and early mortality. Plasmapheresis or plasma exchange (either one referred to here as PLEX) have been used to accelerate free light chain (FLC) removal, despite inconsistent evidence of clinical benefit. Whether PLEX improves renal or survival outcomes in the modern treatment era remains uncertain. Methods: A retrospective multicenter cohort study using the TriNetX Research Network identified newly diagnosed MM pts from 2014-2024 presenting with AKI (an ICD-10 code for acute renal failure or Cr > / = 3.0 mg/dL and a 6 mo prior Cr < 1.5) and laboratory evidence of light chain cast nephropathy (defined as a free light chain concentration > 1,500 mg/L). Pts were included if they received PLEX within 7d of diagnosis, and were compared to those who did not receive PLEX. Pts were excluded if they had pre-existing end stage renal disease. Propensity score matching included demographics, comorbidities, myeloma therapies and laboratory values (Cr, calcium, albumin, hgb). Results: Among 5,454 eligible pts, 251 (4.6%) received PLEX (81% were plasma exchange and 19% were plasmapheresis). After propensity score matching, 248 pts were included in each group with well-balanced baseline characteristics (ex: ave Cr 4.1 and 4.2 in the PLEX vs no PLEX groups, respectively; 38% received PIs in each group). PLEX was not associated with reduced dialysis dependence at 90 days (16.1% vs 18.1%; odds ratio [OR] 0.87, 95% confidence interval [CI] 0.54–1.39) or 180 days (18.5% vs 20.2%; OR 0.90, 95% CI 0.58–1.41). Mortality at 90 (17.7% vs 15%) and 180 days (23.4% vs 23.9%) and ICU admission rates (20% vs 21%) were similar between groups. Dialysis-free survival over 180 days did not differ. Findings were consistent across all prespecified sensitivity analyses, including pts receiving early PI-based therapy and those with extreme free light chain burden (FLC > 5000mg/L, 28% of total cases), with no differences in dialysis dependence or survival. Patients treated with PLEX were numerically more likely to achieve creatinine < 2.0 mg/dL at both 90 days (83.9% vs 77.4%; OR 1.81, 95% CI 0.97–2.38; p = 0.07) and 180 days (86.3% vs 79.8%; OR 1.59, 95% CI 0.98–2.56; p = 0.06), but these differences did not reach statistical significance, except for those with FLC > 5000 (at 90d: 77% vs 63%, p = 0.02; and at 180d: 83% vs 66%, p = 0.006). Conclusions: In this large, contemporary, real-world retrospective cohort, PLEX was not associated with significantly improved renal recovery, dialysis-free survival, or mortality among patients with newly diagnosed myeloma-associated AKI due to light chain nephropathy. These results support current guidelines emphasizing rapid initiation of effective anti-myeloma therapy rather than routine extracorporeal light chain removal.