Hutchison et al. 
demonstrated that irrespective of the treatment modality, recovery of renal function depended on early reduction of sFLCs. In their analysis, a total of 39 patients with biopsy-proven cast nephropathy were included, the majority of whom had severe renal failure at presentation (median eGFR 9 ml/min/1.73 m2
). All patients received a combination of chemotherapy plus direct FLC removal by either plasma exchange (n=20) or extended HCO dialysis (n=19). Following treatment, two-thirds of the patients had some degree of renal recovery. While there was no significant difference in the overall renal recovery rate between the two treatment modalities, the rate of recovery was higher in those treated with HCO dialysis. Importantly, there was a linear relationship between the reduction in sFLCs and renal recovery. Multivariate analysis identified that a 60% reduction in sFLC by day 21 was associated with recovery of renal function in 80% of the study population (Figure 27.15A
). The authors also concluded that the survival of patients with cast nephropathy was closely linked to renal recovery. The median survival of patients who recovered renal function was 42.7 months, compared with 7.8 months in those who did not (p<0.02; Figure 27.15B
The findings of Hutchison et al. are supported by others who highlight the importance of monitoring light chain removal therapy with sFLC measurements. All agreed that sustained reductions in sFLCs consistently predicted renal recovery and improved survival in MM patients with cast nephropathy .