Parameters Associated With Renal Recovery and Survival in Myeloma Patients With Acute Renal Failure to Cast Nephropathy

Acute renal failure due to cast nephropathy (CAN) is a severe complication of multiple myeloma (MM). Here, we aimed to identify parameters associated with renal outcomes and survival in newly diagnosed MM patients with CAN-related acute renal failure and to validate the IMWG criteria for renal response. CAN diagnosis was based on biopsy or clinical assessment. Of 787 registered patients, 354 met the inclusion criteria, requiring at least two therapy cycles with documented chemotherapy response, renal response, and eGFR. Baseline free light chain (FLC) levels (median 6825.65 mg/L) decreased below 500 mg/L in 67.8% of patients. According to IMWG classification, renal complete response, partial response, and minimal response were achieved in 33.9%, 19.5%, and 28.0% of patients, respectively. The best eGFR values > 60 mL/min/1.73 m² were observed in 33.9% of patients, while 33.3%, 22.3%, and 10.5% had best eGFR values of 30-59, 15-29, and < 15 mL/min/1.73 m², respectively. Renal response correlated with baseline FLC levels, IgG kappa, eGFR, and ECOG status in multivariate analysis, as well as with myeloma response and FLC reduction in univariate analysis. Median overall survival was 77.6 months. Survival correlated with age, myeloma response, ECOG status, FLC kappa type, baseline eGFR, standard-risk cytogenetics, and calcium levels, among other factors. A comparison of IMWG renal response criteria with classification based solely on best eGFR showed similar utility. Of 136 patients requiring dialysis, 80 (58.8%) were able to discontinue dialysis during therapy. Bortezomib containing myeloma therapy, along with significant FLC reduction, was associated with favorable outcome.