DNL-151

Portugal-based Bial reported that pariceract (BIA 28-6156; formerly LTI-291, LTI-00291), its oral small-molecule allosteric activator of beta-glucocerebrosidase (GCase), failed to slow disease progression in patients with GBA1 gene-associated Parkinson’s disease, ending development of what had been one of the few mechanism-specific candidates in this genetically defined population. The result closes a program that had enrolled 273 patients across 85 sites in Europe and North America, and deals a further setback to the GCase activation hypothesis in GBA-associated Parkinson’s disease — a subtype affecting an estimated 5%-15% of all Parkinson’s patients and typically characterized by faster motor progression and earlier cognitive decline than idiopathic disease. The ACTIVATE trial was a Phase IIb, multicenter, randomized, double-blind, placebo-controlled study evaluating pariceract in genetically confirmed GBA-PD patients across two fixed oral doses (10 mg/day and 60 mg/day). Enrollment of 273 patients took approximately 18 months, with sites spanning 11 countries. The study assessed efficacy, safety, tolerability, pharmacodynamics, and pharmacokinetics. Bial announced the first patient to complete the full dose regimen in January 2025, with topline data expected mid-2026. Neither the primary endpoint nor the key secondary efficacy endpoints were met. Bial did not disclose the specific primary endpoint measure or numerical efficacy data in the topline release, stating only that pariceract “failed to slow the progression of GBA-PD versus placebo”. The drug was reported as generally well tolerated, with no unexpected safety concerns identified — a finding that does not rescue the program but may inform future mechanistic work in the field. Based on the absence of demonstrated efficacy, Bial has discontinued further development of pariceract for this indication. Competitive context The GCase activation space has now accumulated two high-profile clinical failures in rapid succession. In May 2026, Biogen (Nasdaq: BIIB) and Denali Therapeutics (Nasdaq: DNLI) reported that BIIB122 (DNL151), a small-molecule LRRK2 inhibitor, failed its Phase IIb LUMA study in early-stage idiopathic Parkinson’s disease — a different target but another genetically informed disease-modification strategy that did not translate into clinical benefit. While the LUMA failure involved a distinct mechanism and broader patient population, it reinforces the difficulty of demonstrating disease modification in Parkinson’s with current trial designs and endpoints. Within the GCase space specifically, competitors remain active at earlier stages. Maryland-based Gain Therapeutics (Nasdaq: GANX) is advancing GT-02287, a GCase allosteric modulator, in a Phase Ib extension study in patients with Parkinson’s disease with or without a GBA1 mutation. Interim data presented in May 2026 showed stable MDS-UPDRS scores over 150 days and a differential response pattern in patients with elevated baseline cerebrospinal fluid glucosylsphingosine, a GCase substrate biomarker — though the study was not designed to assess clinical efficacy. Chicago-based Vanqua Bio reported Phase Ib data in March 2026 showing that VQ-101, another oral GCase activator, achieved greater than 50% activation of lysosomal GCase in GBA-Parkinson’s patients, meeting a pre-specified target engagement goal. Both programs remain substantially earlier in development than pariceract was at the time of its failure. Cross-trial comparisons are limited by differences in patient populations, dose levels, trial duration, and endpoint selection, and the mechanistic success of earlier-stage programs does not predict Phase II outcomes. The pariceract result will prompt scrutiny of whether GCase target engagement alone — without demonstrated downstream effects on alpha-synuclein aggregation or neurodegeneration — is sufficient to support efficacy hypotheses in GBA-PD clinical trials. The failure also raises questions about trial design in this space. GBA-PD patients progress faster than idiopathic PD patients on average, which theoretically improves statistical power to detect disease modification over a given timeframe. Whether the ACTIVATE study was adequately powered, whether the doses selected achieved sufficient central nervous system GCase activation, and whether the primary endpoint was sensitive enough to detect clinically meaningful slowing will be central questions when Bial presents full data at scientific meetings. The company said it intends to disseminate the ACTIVATE data through peer-reviewed publications and conferences. For Bial, which invests over 20% of annual revenue in R\&D and has focused its neuroscience pipeline on Parkinson’s disease, the discontinuation removes what had been a lead disease-modification asset. The company’s approved portfolio includes opicapone (Ongentys), a COMT inhibitor used as adjunct therapy to levodopa in Parkinson’s patients with motor fluctuations — a symptomatic treatment that competes in a different segment of the disease management landscape. Pariceract had represented Bial’s attempt to move upstream toward disease modification in a genetically defined subpopulation, a strategy that now requires reassessment. This article was generated with AI assistance and reviewed and edited by the AllSci editorial team Explore more at AllSci News: https://allsci.com/news/ Your email address will not be published. Required fields are marked * Comment * Name * Email * Website Privacy Terms About Us Copyright © 2026. AllSci Corp. All rights reserved.