Renal function decline with small interfering RNA silencing ALAS1

Abstract Introduction Givosiran is an RNA interference therapeutic designed to block the synthesis of the ALAS1 enzyme in patients with acute intermittent porphyria. Givosiran may have adverse effects on the kidney. Methods We performed a descriptive case series of renal function parameters of all the patients who received givosiran in France. Twenty patients receiving givosiran between March 2018 and July 2020 in France were analyzed: 7 patients in the ENVISION trial, and 13 patients treated in relationship with the Centre de Reference Maladies Rares Prophyries. Results A transient decrease in renal function was observed in all but 2 patients (90%) within the 3 months following givosiran initiation. None of the patients developed Acute Kidney Injury/Disease. Patients of the ENVISION cohort were followed for at least 30 months: 2 patients did not experience eGFR loss, 3 patients experienced a modest decline in renal function (-3.4 ml/minute/1.73 m2/year in average), and 2 patients had a clearly abnormal eGFR loss (-5.8 ml/minute/1.73 m2/year in average). None of the patients had biochemical signs of active tubular or glomerular injury. One patient’s kidney was biopsied without finding sign of an active kidney disease and with normal ALAS1 tubular expression. Conclusions Givosiran is associated with a transient moderate increase in sCr without sign of kidney injury. A long-term deleterious impact of ALAS1 inhibition on renal function is not excluded. Since AIP promotes chronic kidney disease, it is difficult to separate the long-term effects of givosiran from the natural progression of the renal disease.