C RATNAYAKE 1, S GIBBS 2,3, D LEE 1,2
1Department of Renal Medicine, Eastern Health, Box Hill, Australia , 2Eastern Health Clinical School, Monash University, Box Hill, Australia , 3Department of Haematology, Eastern Health, Box Hill, Australia
Aim: To evaluate the renal outcomes and identify favourable factors after myeloma cast nephropathy (MCN) diagnosis in the contemporary era of plasma cell directed anti-myeloma therapy.
Background: MCN has historically been associated with poor renal outcomes.
Methods: Patients who received anti-myeloma therapy for MCN (January 2012 to June 2020) from a single centre were retrospectively identified from electronic medical records, either biopsy confirmed (BC) or clinically diagnosed (CD) without a kidney biopsy (defined as acute kidney injury with CKD-EPI eGFR <30 mL/min/1.73m2 and involved serum free light chains (iSFLC) >500 mg/L at diagnosis). Factors associated with best post-treatment eGFR achieved were evaluated.
Results:Twenty-six patients with MCN were identified (BC n=13, CD n=13). 50% died during a median follow-up of 27 (IQR 20-54) months, and they were older (81 (77-85) versus 65 (61-72) years; P=0.01). eGFR at diagnosis was 12 (6-21) mL/min/1.73m2, improving to 47 (29-57) mL/min/1.73m2 at 12 months. The best eGFR achieved was 47 (32-67) mL/min/1.73m2 after 120 (63-167) days post-treatment. All 6 dialysis-requiring patients achieved dialysis independence (median 71 days). Compared with CD-MCN patients, BC-MCN patients were younger (65 (61-81) versus 78 (77-85) years; P<0.05) and more likely dialysis-requiring (46% versus 0%; P<0.001). Patients with best post-treatment eGFR above versus below the median were more likely to have achieved an iSFLC of <20 mg/L (62% versus 0%; P<0.001), lower best post-treatment iSFLC (20 (12-90) versus 67 (29-146) mg/L; P<0.05), but no difference in iSFLC level at diagnosis.
Conclusion: Best iSFLC achieved was a predictor for superior eGFR post-MCN treatment. Despite low eGFR at diagnosis, contemporary anti-myeloma therapy can achieve satisfactory renal outcomes. However, mortality remains high in the older population.
Chathri Ratnayake is a first year renal advanced trainee from Victoria.