Bosutinib versus Placebo for Autosomal Dominant Polycystic Kidney Disease

Abstract

Overactivation of Src has been linked to the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD). This phase 2, multisite study assessed the efficacy and safety of bosutinib, an oral dual Src/Bcr-Abl tyrosine kinase inhibitor, in patients with ADPKD. Patients with ADPKD, eGFR≥60 ml/min per 1.73 m², and total kidney volume ≥750 ml were randomized 1:1:1 to bosutinib 200 mg/d, bosutinib 400 mg/d, or placebo for ≤24 months. The primary endpoint was annualized rate of kidney enlargement in patients treated for ≥2 weeks who had at least one postbaseline magnetic resonance imaging scan that was preceded by a 30-day washout (modified intent-to-treat population). Of 172 enrolled patients, 169 received at least one study dose. Per protocol amendment, doses for 24 patients who initially received bosutinib at 400 mg/d were later reduced to 200 mg/d. The annual rate of kidney enlargement was reduced by 66% for bosutinib 200 mg/d versus placebo (1.63% versus 4.74%, respectively; P=0.01) and by 82% for pooled bosutinib versus placebo (0.84% versus 4.74%, respectively; P<0.001). Over the treatment period, patients receiving placebo or bosutinib had similar annualized eGFR decline. Gastrointestinal and liver-related adverse events were the most frequent toxicities. In conclusion, compared with placebo, bosutinib at 200 mg/d reduced kidney growth in patients with ADPKD. The overall gastrointestinal and liver toxicity profile was consistent with the profile in prior studies of bosutinib; no new toxicities were identified. (ClinicalTrials.gov: NCT01233869).

Keywords: ADPKD; Src; bosutinib; clinical trial; total kidney volume.

Figure 1.

Subject disposition. *Three patients were not administered study treatment: two were randomized but discontinued before treatment, and one did not receive any study treatment and was reassigned a new randomization number because of accidental unblinding. ^†Includes one patient with a status of “ongoing” but who discontinued before the end of the initial treatment period because the summary page from this patient’s case report form was not recorded. BOS, bosutinib; mITT, modified intent-to-treat population.

Figure 2.

No significant change in serum creatinine over time. Boxes represent the 25th, 50th, and 75th percentiles; whiskers represent an extension of 1.5× the interquartile range; stars represent mean value; circles represent individual values out of interquartile range. D, day; EE, end of extended treatment; EI, end of initial treatment; ET, early termination; M, month.