PrimeC Shows Promise in Slowing ALS Progression in Phase 2b Trial

A latest oral therapy, PrimeC, is showing promise for individuals living with amyotrophic lateral sclerosis (ALS), offering a potential slowing of disease progression and a reduced risk of complications, according to findings published in JAMA Neurology on March 26, 2026. The treatment, a combination of celecoxib and ciprofloxacin, was well-tolerated in a phase 2b randomized controlled trial, prompting researchers to advocate for a larger phase 3 study to further evaluate its effectiveness and safety.

PrimeC’s Impact on ALS Progression

The trial involved 68 participants diagnosed with definite or probable ALS, randomly assigned to receive either PrimeC or a placebo for six months, followed by a 12-month open-label extension where all participants received PrimeC. Researchers observed that those treated with PrimeC demonstrated improved functionality compared to the placebo group, with a signify score increase of 2.23 points on the ALS Functional Rating Scale-Revised (ALSFRS-R) at the six-month mark. This difference grew to 7.92 points at 18 months, particularly noticeable in bulbar function – the muscles responsible for speech and swallowing – where a significant difference of 3.18 points was recorded.

Beyond functional improvements, the study indicated a substantial reduction in the risk of ALS-related complications for those on PrimeC. Specifically, the therapy lowered the risk of hospitalization, respiratory failure, or death by 64% (HR = 0.36; 95% CI, 0.15–0.85). This suggests a potential for PrimeC to not only slow disease progression but also to improve the overall clinical course for individuals with ALS.

Understanding the Mechanism of Action

ALS is a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord, leading to muscle weakness, paralysis and eventually death. The precise causes of ALS are not fully understood, but research suggests a complex interplay of genetic and environmental factors. PrimeC is designed to address several key pathological processes implicated in ALS: neuroinflammation, excessive iron accumulation, and abnormal microRNA activity. The combination of celecoxib, a nonsteroidal anti-inflammatory drug (NSAID), and ciprofloxacin, an antibiotic, aims to modulate these processes and protect nerve cells from further damage.

Trial Details and Safety Profile

The phase 2b trial, led by Merit Cudkowicz, MD, MSc, of Mass General Brigham Neuroscience Institute, included a relatively balanced group of participants, with 60% men in the PrimeC group and 60.9% men in the placebo group. The average age was approximately 59 years in the PrimeC group and 55 years in the placebo group. The study’s design involved a double-blind, randomized controlled approach, considered a robust method for evaluating treatment efficacy.

Adverse event rates were comparable between the two groups – 66.7% for PrimeC and 65.2% for placebo – indicating that the therapy was generally well-tolerated. While drug-related adverse events were more frequent in the PrimeC group (20% vs. 4.3%), these were largely mild to moderate and temporary in nature. This favorable safety profile is a crucial aspect of PrimeC’s potential as a viable treatment option for ALS.

Biomarker Signals and Future Research

Beyond clinical outcomes, the study also examined changes in key biomarkers associated with ALS. Participants treated with PrimeC exhibited lower levels of transferrin, a protein involved in iron transport, and reduced levels of ALS-related microRNAs, small molecules that regulate gene expression. These biomarker changes align with the therapy’s intended mechanism of action and provide further support for its potential efficacy.

Jeremy M. Shefner, MD, PhD, a study co-author from Barrow Neurological Institute, emphasized the consistency of the findings. “What stands out about the PARADIGM study is that multiple clinical endpoints suggest the same level of clinical benefit and that multiple biomarkers are consistent with clinical endpoints,” he stated in a press release. This convergence of clinical and biomarker data strengthens the rationale for advancing PrimeC into a phase 3 trial.

Contextualizing the Findings: ALS Treatment Landscape

ALS remains a challenging disease to treat, with limited therapeutic options available. Current treatments primarily focus on managing symptoms and improving quality of life, but few therapies have demonstrated a significant ability to slow disease progression. Healio previously reported on earlier data from the PARADIGM study, which showed a 43% better survival rate for patients prescribed PrimeC after one year. The latest findings build upon this earlier evidence, further bolstering the case for PrimeC as a potential disease-modifying therapy.

The development of PrimeC is particularly noteworthy given the complex pathophysiology of ALS. The therapy’s multi-targeted approach, addressing neuroinflammation, iron accumulation, and microRNA dysregulation, reflects a growing understanding of the disease’s intricate mechanisms. This approach contrasts with some earlier ALS therapies that focused on single targets, often with limited success.

What Comes Next: Phase 3 Trial and Beyond

The researchers are now preparing for a phase 3 clinical trial to confirm the efficacy and safety of PrimeC in a larger and more diverse population. This trial will be crucial for determining whether the promising results observed in the phase 2b study can be replicated and whether PrimeC can ultimately become an approved treatment for ALS. The design of the phase 3 trial will likely incorporate lessons learned from the earlier study, including refinements to patient selection criteria and outcome measures.

The timeline for the phase 3 trial and potential regulatory approval remains uncertain. However, the positive data from the phase 2b study have generated significant excitement within the ALS research community and offer renewed hope for individuals and families affected by this devastating disease. Ongoing research will also focus on identifying biomarkers that can predict treatment response and personalize therapy for individual patients.

Source: Cudkowicz M, et al. JAMA Neurol. 2026;doi:10.1001/jamaneurol.2026.0230.