Effect of Sirolimus on Disease Progression in Patients with Autosomal Dominant Polycystic Kidney Disease and CKD Stages 3b-4

Abstract

Background and objectives: The effect of mammalian target of rapamycin (mTOR) inhibitors has never been tested in patients with autosomal dominant polycystic kidney disease (ADPKD) and severe renal insufficiency.

Design, setting, participants, & measurements: In this academic, prospective, randomized, open label, blinded end point, parallel group trial (ClinicalTrials.gov no. NCT01223755), 41 adults with ADPKD, CKD stage 3b or 4, and proteinuria ≤0.5 g/24 h were randomized between September of 2010 and March of 2012 to sirolimus (3 mg/d; serum target levels of 5-10 ng/ml) added on to conventional therapy (n=21) or conventional treatment alone (n=20). Primary outcome was GFR (iohexol plasma clearance) change at 1 and 3 years versus baseline.

Results: At the 1-year preplanned interim analysis, GFR fell from 26.7±5.8 to 21.3±6.3 ml/min per 1.73 m(2) (P<0.001) and from 29.6±5.6 to 24.9±6.2 ml/min per 1.73 m(2) (P<0.001) in the sirolimus and conventional treatment groups, respectively. Albuminuria (73.8±81.8 versus 154.9±152.9 μg/min; P=0.02) and proteinuria (0.3±0.2 versus 06±0.4 g/24 h; P<0.01) increased with sirolimus. Seven patients on sirolimus versus one control had de novo proteinuria (P=0.04), ten versus three patients doubled proteinuria (P=0.02), 18 versus 11 patients had peripheral edema (P=0.04), and 14 versus six patients had upper respiratory tract infections (P=0.03). Three patients on sirolimus had angioedema, 14 patients had aphthous stomatitis, and seven patients had acne (P<0.01 for both versus controls). Two patients progressed to ESRD, and two patients withdrew because of worsening of proteinuria. These events were not observed in controls. Thus, the independent data and safety monitoring board recommend early trial termination for safety reasons. At 1 year, total kidney volume (assessed by contrast-enhanced computed tomography imaging) increased by 9.0% from 2857.7±1447.3 to 3094.6±1519.5 ml on sirolimus and 4.3% from 3123.4±1695.3 to 3222.6±1651.4 ml on conventional therapy (P=0.12). On follow-up, 37% and 7% of serum sirolimus levels fell below or exceeded the therapeutic range, respectively.

Conclusions: Finding that sirolimus was unsafe and ineffective in patients with ADPKD and renal insufficiency suggests that mTOR inhibitor therapy may be contraindicated in this context.

Keywords: Adult; Humans; Polycystic Kidney, Autosomal Dominant; Prospective Studies; Renal Insufficiency; adverse effects; kidney failure, chronic; proteinuria; randomized controlled trials; sirolimus.

Figure 1.

Study flow diagram.

Figure 2.

GFR changes during the study according to treatment groups. Mean±SD. GFR at baseline and 6 and 12 months of follow-up (left panel) and percentage GFR changes at 6 and 12 months of follow-up versus baseline (right panel). GFR values at different time points and GFR changes versus baseline did not differ significantly between treatment groups.

Figure 3.

Changes in twenty-four–hour albuminuria and proteinuria during the study according to treatment groups. Median (interquartile range) 24-hour albuminuria (left panel) and proteinuria (right panel) at baseline and 6 and 12 months of follow-up. Albuminuria and proteinuria both increased in the sirolimus group. At 12 months, changes in both parameters were significantly different between the two treatment groups. *P<0.05 versus conventional therapy (analysis of covariance); **P<0.01 versus conventional therapy (analysis of covariance); °P<0.05 versus baseline; °°P<0.01 versus baseline.

Figure 4.

Individual patient total kidney values at baseline and 12 months of follow-up according to treatment groups. No significant change was observed in the sirolimus (left panel) and conventional therapy (right panel) groups. Circles identify single-patient data, and horizontal thick lines denote mean values.