Admilparant's Fatal Liver Signal Puts LPA1R Class Thesis Under Direct Clinical Test

Bristol Myers Revises Pulmonary Fibrosis Trial Due to Liver Concerns

Bristol Myers Squibb (BMS) has revised its Phase 3 "Aloft" trial for admilparant, an experimental drug for idiopathic pulmonary fibrosis, to enhance monitoring for liver-related side effects. This decision follows a "limited number" of liver damage incidents and one patient death from liver injury, though a direct link to the drug remains unconfirmed. The news sparked investor concern over admilparant and the broader LPA1R inhibitor class, causing initial share declines for BMS and Contineum Therapeutics before a rebound. BMS anticipates reporting full study results by the end of the year, which is expected to provide further clarity on the drug's safety profile.

• Bristol Myers Squibb amended its Phase 3 "Aloft" trial for admilparant, an LPA1R inhibitor for idiopathic pulmonary fibrosis, to implement stricter monitoring for liver-related side effects. This decision was prompted by a "limited number" of liver damage events and one patient fatality attributed to multi-organ failure with liver damage, although a direct causal link to admilparant remains unconfirmed. The amendment specifically classified liver injury as a "newly classified important potential risk" for EU sites.
• The news triggered a sharp decline in shares for both Bristol Myers Squibb and Contineum Therapeutics, which is developing a similar LPA1R inhibitor. This market reaction reflects renewed investor apprehension regarding the safety profile of the entire LPA1R inhibitor class, which has a history of liver toxicity issues, including previous drug cancellations by BMS and Amgen. Analysts, however, suggested the pullback might be "overdone" given the mild nature of most reported events and the uncertainty of drug causation.
• The amendment to the admilparant trial adds to the scrutiny of Bristol Myers Squibb's pipeline, as the company faces patent expirations for key revenue drivers like Eliquis. Despite the safety concerns, outside trial monitors have consistently recommended the study's continuation. Bristol Myers anticipates reporting full study results by the end of the year, which will be crucial in determining the future of admilparant and potentially restoring confidence in the LPA1R inhibitor class for idiopathic pulmonary fibrosis treatment.

Admilparant's Liver Safety Profile in IPF Trial

In the phase 2 randomized, double-blind, placebo-controlled trial (NCT04308681), admilparant (BMS-986278) was evaluated at 30 mg and 60 mg twice daily for 26 weeks in parallel cohorts of patients with IPF (n = 276 treated) and PPF (n = 123 treated). Diarrhea occurred at similar frequencies in admilparant arms versus placebo across both cohorts. Transient Day 1 postdose blood pressure reductions were observed in all arms in both cohorts but were greater with admilparant. These findings characterize the principal tolerability signals identified across the studied indications.

Treatment discontinuations due to adverse events were similar across IPF arms. In the PPF cohort, discontinuation rates were notably lower with admilparant — 2.5% in the 30 mg arm and 0% in the 60 mg arm — compared with 17.1% in the placebo arm. This pattern held in the context of permitted background antifibrotics in both cohorts and immunosuppressants in the PPF cohort, suggesting that admilparant's tolerability profile was not substantially altered by concomitant therapy.

Biomarker analyses from the same trial provide additional mechanistic context for the tolerability profile. In the IPF cohort, 60 mg admilparant was associated with decreased circulating markers of epithelial injury and fibrosis, including CA-125/MUC16, MMP-7, TN-C, and PRO-FIB, alongside increased adiponectin, MMIF, CD163, CEA, and ENRAGE. In the PPF cohort, significant changes included decreased periostin, IL6Rβ, CD163, KIM-1, multiple inflammatory markers, and collagen degradation markers. Overall, 60 mg admilparant was characterized as safe and well tolerated in this phase 2 study, supporting further evaluation in phase 3 trials.

Navigating the Aloft Trial's Revised Design and IPF Endpoints

Several landmark trials have shaped the clinical development landscape for idiopathic pulmonary fibrosis (IPF), evaluating both antifibrotic agents — nintedanib and pirfenidone — across Phase 2 and Phase 3 settings. The trials below span single-centre real-world cohorts to large multinational randomised controlled studies, with FVC decline as the consistent primary efficacy anchor.

Admilparant's Liver Safety: A Pivotal Test for LPA1 Antagonists

Idiopathic pulmonary fibrosis (IPF) and progressive pulmonary fibrosis (PPF) represent a significant challenge in respiratory medicine, characterized by irreversible lung function decline and high mortality. Current treatments offer only modest benefits, slowing but not halting disease progression, and often come with tolerability issues that lead to discontinuation. This unmet need has fueled the search for novel therapies, with lysophosphatidic acid receptor 1 (LPA1) antagonists emerging as a promising class.

Admilparant (BMS-986278), an oral LPA1 antagonist, has shown encouraging results in Phase 2 trials, demonstrating a slowed rate of lung function decline and delayed disease progression in both IPF and PPF patients. These findings supported its advancement into Phase 3, offering hope for a new therapeutic option. However, the recent news of liver damage incidents and a patient death in the ongoing Phase 3 "Aloft" trial introduces a critical safety signal.

This development is particularly sensitive given the history of the LPA1 antagonist class. A previous compound, BMS-986020, was discontinued due to hepatobiliary toxicity. While nonclinical studies had suggested that admilparant's safety profile was distinct and not a class-wide issue, the current events necessitate a re-evaluation. Bristol Myers Squibb's decision to enhance monitoring for liver-related side effects reflects a proactive approach to risk mitigation, aiming to thoroughly characterize the drug's safety profile.

The strategic implications are clear: BMS is signaling confidence in admilparant's overall benefit-risk profile, believing the liver events are manageable or not directly attributable to the drug. However, this situation will undoubtedly lead to heightened regulatory scrutiny, potentially impacting the timeline and conditions of any future approval. Furthermore, the commercial viability of admilparant, even if approved, could be influenced by physician and patient perception of its safety, especially when compared to existing therapies. The upcoming full study results by year-end will be pivotal, not only for admilparant and BMS but also for the future development and market acceptance of the entire LPA1 antagonist class in fibrotic lung diseases.