#1716 Polymethylmethacrylate membranes: a cost-effective and viable strategy for renal recovery in multiple myeloma

Abstract Background and Aims Acute kidney injury (AKI) due to cast nephropathy is a complication in multiple myeloma (MM), 20–50% at diagnosis. Current therapeutic, such as high-cut-off (HCO) hemodialysis, its reduces serum free light chains (FLCs) but associated with high costs and albumin loss. Polymethylmethacrylate (PMMA) membranes have emerged as a cost-effective alternative, with comparable efficacy in FLC reduction and renal recovery. We evaluate the outcomes of intensive hemodialysis with PMMA membranes in MM patients with severe AKI-3. Method A single-center, prospective observational study included 13 patients with MM and AKI-3 between June 2019-December 2023, followed at least one year. All patients underwent intensive high-flow hemodialysis with PMMA and standard chemotherapy. Serum FLC levels (kappa and lambda), glomerular filtration rate [GFR], and patient survival were monitored. Renal response was categorized to the International Myeloma Working Group (IMWG). Statistical analyses: Wilcoxon tests for pre- and post-treatment comparisons and mixed-effects models for renal function trends. Results PMMA membranes reduced in FLC levels, median values falling below 500 mg/L after a mean of 11.5 sessions (standard deviation [SD] = 4.6). The reductions were both clinically and statistically significant (P = 0.003 for kappa chains; P = 0.0024 for lambda chains). At the end of follow-up, 23% of patients achieved complete renal response (eGFR <50 mL/min and best clearance ≥60 mL/min), 7% achieved partial response ( eGFR <15 mL/min and best creatinine clearance 30–59 mL/min), and 30% achieved minor response ( eGFR <15 mL/min with best creatinine clearance 15–29 mL/min), while 38% no response. (Criteria by IMWG). Significant association between renal response at one year and survival (P = 0.017). Patients without renal response had the highest mortality (80%). Among survivors, 53.8% achieved GFR > 20 mL/min/1.73 m², increasing at 12 months (P < 0.001 to baseline). PMMA membranes demonstrated comparable effectiveness to other extracorporeal therapies with a significantly lower costs. Conclusion Intensive hemodialysis with PMMA are a cost-effective and viable strategy for FLC reduction and renal recovery in MM with AKI-3, comparable in efficacy to expensive therapies. Early and effective FLC removal is crucial for improving renal outcomes and reducing mortality. While these findings align with previous studies, further multicenter research is essential to establish PMMA as a standard therapy.