AMX0035 is a combination of two small molecule compounds: sodium phenylbutyrate and tauroursodeoxycholic acid (TUDCA). Sodium phenylbutyrate is a pan HDAC inhibitor and is approved by the FDA to treat urea cycle disorders. TUDCA is bile acid naturally produced by the liver but is not approved by the FDA for any marketing use. AMX0035 recently completed enrollment of a phase two trial in mid 2019.

The trial, known as the CENTAUR trial, was conducted by Amylyx. It was a randomized, double-blind, placebo-controlled study to evaluate the safety and efficacy of AMX0035. The trial is currently fully enrolled, but there is an ongoing open label extension arm, to assess the long term safety of the drug. Sodium phenylbutyrate has been described as a potential treatment for ALS for more than a decade based on preclinical results from rodent models of ALS. Unfortunately, other labs, including ALS TDI, have not been able to reproduce these results.

Early clinical trials of the components have been done in Italy, South Korea and elsewhere by groups other than Amylyx. When tested separately in those clinical trials, the use of the compounds by themselves was found safe and well tolerated in people with ALS. However, no clinical trials examining these molecules to date have found them to show efficacy in people with ALS. This trial, is the first combination study of the two together in people with ALS. Amylyx decided to pursue AMX0035 following a high throughput screen and found this combination of sodium phenylbutyrate and TUDCA to be the most neuroprotective.