P105
EARLY REDUCTIONS IN SERUM IMMUNOGLOBULIN FREE LIGHT CHAINS
(FLC) PREDICT RENAL RECOVERY IN MYELOMA KIDNEY AND DIALYSISDEPENDENT AKI
Hutchison, C¹, Leung, N², Stringer, S¹, Cockwell, P¹
¹Renal Institute of Birmingham, University Hospitals Birmingham, ²The Mayo Clinic,
Rochester, USA
PROBLEMS: Dialysis-dependent acute kidney injury (AKI) occurs in up to 10% of patients
with multiple myeloma (MM) and in 90% of cases is caused by myeloma kidney (cast
nephropathy) secondary to high levels of immunoglobulin free light chains (FLC). The majority
of patients fail to recover renal function with a subsequent median survival of around 6 months.
PURPOSE: To assess the relationship between early disease response as measured by serum
FLCs we: (i) have performed a detailed analysis of the kinetics of FLC levels and renal recovery
in myeloma in severe AKI; (ii) report FLC levels and renal recovery rates in an international
multicentre cohort of patients treated with chemotherapy and high cut-off haemodialysis (HCOHD)
DESIGN: (i) 39 patients with AKI secondary to biopsy proven myeloma kidney who
underwent multiple sampling for serum FLC measurements at two centres were studied. Renal
recovery was defined as independence of dialysis (24 patients were dialysis dependent) or an
incremental increase in eGFR for non-dialysis dependence. (ii) The outcomes of 67 patients
(reported by centres from 9 countries) with multiple myeloma and dialysis dependent AKI
treated with chemotherapy and HCO-HD were analysed to assess renal recovery and serum FLC
reductions.
FINDINGS: (i) Multi-variant analysis showed that FLC reduction was the only independent
determinant of renal recovery. The relationship between renal recovery and FLC reduction was
linear; modelling the clinical and serological responses showed that for an 80% chance of renal
recovery a 60% reduction in FLCs is required by day 21 from diagnosis. (ii) In the HCO cohort
63% had a sustained reduction in serum FLCs; 71% of these patients subsequently became
independent of dialysis. Factors which independently predicted renal recovery in this group
were the degree of FLC reduction from starting therapy (p=0.005) and the time to initiating
HCO-HD (P=0.006).
CONCLUSION: An early reduction of serum FLC concentrations optimises recovery kidney
failure in the setting of multiple myeloma.
RELEVANCE: We have defined serum FLC levels that provide clinicians and their patients
with an early prognostic determinant. These data will encourage the early tailoring of therapy to
facilitate improved rates of renal recovery and patient survival in this setting.