Activation of mammalian target of rapamycin (mTOR) pathways may contribute to uncontrolled cell proliferation and secondary cyst growth in patients with autosomal dominant polycystic kidney disease (ADPKD). To assess the effects of mTOR inhibition on disease progression, we performed a randomized, crossover study (The SIRENA Study) comparing a 6-month treatment with sirolimus or conventional therapy alone on the growth of kidney volume and its compartments in 21 patients with ADPKD and GFR Ն40 ml/min per 1.73 m 2 . In 10 of the 15 patients who completed the study, aphthous stomatitis complicated sirolimus treatment but was effectively controlled by topical therapy. Compared with pretreatment, posttreatment mean total kidney volume increased less on sirolimus (46 Ϯ 81 ml; P ϭ 0.047) than on conventional therapy (70 Ϯ 72 ml; P ϭ 0.002), but we did not detect a difference between the two treatments (P ϭ 0.45). Cyst volume was stable on sirolimus and increased by 55 Ϯ 75 ml (P ϭ 0.013) on conventional therapy, whereas parenchymal volume increased by 26 Ϯ 30 ml (P ϭ 0.005) on sirolimus and was stable on conventional therapy. Percentage changes in cyst and parenchyma volumes were significantly different between the two treatment periods. Sirolimus had no appreciable effects on intermediate volume and GFR. Albuminuria and proteinuria marginally but significantly increased during sirolimus treatment. In summary, sirolimus halted cyst growth and increased parenchymal volume in patients with ADPKD. Whether these effects translate into improved long-term outcomes requires further investigation.

Background and objectives: No medical treatment is available for polycystic liver disease, a frequent manifestation of autosomal-dominant polycystic kidney disease (ADPKD). In a prospective, randomized, double-blind, crossover study, 6 months of octreotide (40 mg every 28 days) therapy limited kidney volume growth more effectively than placebo in 12 patients with ADPKD.Design, setting, participants, & measurements: In this secondary, post hoc analysis of the above study, octreotide-induced changes in liver volumes compared with placebo and the relationship between concomitant changes in liver and kidney volumes were evaluated. Those analyzing liver and kidney volumes were blinded to treatment.Results: Liver volumes significantly decreased from 1595 ؎ 478 ml to 1524 ؎ 453 ml with octreotide whereas they did not appreciably change with placebo. Changes in liver volumes were significantly different between the two treatment periods (؊71 ؎ 57 ml versus ؉14 ؎ 85 ml). Octreotide-induced liver volume reduction was fully explained by a reduction in parenchyma volume from 1506 ؎ 431 ml to 1432 ؎ 403 ml. Changes in liver volumes were significantly correlated with concomitant changes in kidney volumes (r ‫؍‬ 0.67) during octreotide but not during placebo treatment. Liver and kidney volume changes significantly differed with both treatments (octreotide: ؊71 ؎ 57 ml versus ؉71 ؎ 107; placebo: ؉14 ؎ 85 ml versus ؉162 ؎ 114), but net reductions in liver (؊85 ؎ 103 ml) and kidney (؊91 ؎ 125 ml) volume growth on octreotide versus placebo were similar.Conclusions: Octreotide therapy reduces liver volumes in patients with ADPKD and is safe.