Evaluation of PXL065 - deuterium-stabilized (R)-pioglitazone in patients with NASH: A phase II randomized placebo-controlled trial (DESTINY-1)

Background & aims: Pioglitazone (Pio) is efficacious in NASH, but its utility is limited by PPARγ-driven side effects. Pio is a mixture of two enantiomers (R, S). PXL065, deuterium-stabilized R-Pio, lacks PPARγ activity but retains non-genomic activity. We tested the hypothesis that PXL065 would have similar efficacy but a better safety profile than Pio in patients with NASH.

Methods: Patients (≥8% liver fat, NAFLD activity score [NAS] ≥4, F1-F3) received daily doses of PXL065 (7.5, 15, 22.5 mg) or placebo 1:1:1:1 for 36 weeks. The primary endpoint was relative % change in liver fat content (LFC) on MRI-proton density fat fraction; liver histology, non-invasive tests, safety-tolerability, and pharmacokinetics were also assessed.

Results: One hundred and seventeen patients were evaluated. All PXL065 groups met the primary endpoint (-21 to -25% LFC, p = 0.008-0.02 vs. placebo); 40% (22.5 mg) achieved a ≥30% LFC reduction. Favorable trends in non-invasive tests including reductions in PIIINP (p = 0.02, 22.5 mg) and NAFLD fibrosis score (p = 0.04, 22.5 mg) were observed. On histology (n = 92), a ≥1 stage fibrosis improvement occurred in 40% (7.5 mg), 50% (15 mg, p = 0.06), and 35% (22.5 mg) vs. 17% for placebo; up to 50% of PXL065-treated patients achieved a ≥2 point NAS improvement without fibrosis worsening vs. 30% with placebo. Metabolic improvements included: HbA1c (-0.41% p = 0.003) and insulin sensitivity (HOMA-IR, p = 0.04; Adipo-IR, p = 0.002). Adiponectin increased (+114%, 22.5 mg, p <0.0001) vs. placebo. There was no dose-dependent effect on body weight or PXL065-related peripheral oedema signal. Overall, PXL065 was safe and well tolerated. Pharmacokinetics confirmed dose-proportional and higher steady state R- vs. S-Pio exposure.

Impact and implications: Pioglitazone (Pio) is an approved diabetes medicine with proven efficacy in non-alcoholic steatohepatitis (NASH); PXL065 is a novel related oral agent which has been shown to retain Pio's efficacy in preclinical NASH models, with reduced potential for PPARγ-driven side effects. Results of this phase II study are important as PXL065 improved several key NASH disease features with a favorable safety profile - these findings can be applied by researchers seeking to understand pathophysiology and to develop new therapies. These results also indicate that PXL065 warrants further clinical testing in a pivotal NASH trial. Other implications include the potential future availability of a distinct oral therapy for NASH that may be relevant for patients, providers and caregivers seeking to prevent the progression and complications of this disease.

Conclusions: PXL065 is a novel molecule which retains an efficacy profile in NASH similar to Pio with reduced potential for PPARγ-driven side effects. A pivotal clinical trial is warranted to confirm the histological benefits reported herein.

Impact and implications: Pioglitazone (Pio) is an approved diabetes medicine with proven efficacy in non-alcoholic steatohepatitis (NASH); PXL065 is a novel related oral agent which has been shown to retain Pio's efficacy in preclinical NASH models, with reduced potential for PPARγ-driven side effects. Results of this phase II study are important as PXL065 improved several key NASH disease features with a favorable safety profile - these findings can be applied by researchers seeking to understand pathophysiology and to develop new therapies. These results also indicate that PXL065 warrants further clinical testing in a pivotal NASH trial. Other implications include the potential future availability of a distinct oral therapy for NASH that may be relevant for patients, providers and caregivers seeking to prevent the progression and complications of this disease.