Seelos had hoped to report a sweet victory for its amyotrophic lateral sclerosis treatment, but the IV-delivered sugar failed to distinguish itself in a phase 2/3 trial.
The New York biotech said Tuesday that SLS-005 didn't demonstrate a significant improvement in slowing disease severity compared to placebo, flunking the study’s primary endpoint. The treatment was also unable to spur a statistically significant improvement in patients’ physical function or mortality rates.
Searching for a silver lining, the biotech pointed to a pre-specified subgroup of patients who hadn't also received Amylyx’s now-in-flux treatment Relyvrio. In those 130 patients, SLS-005 demonstrated a 22% improvement in slowing the pace of disease progression and 25% slowing in the pace of respiratory decline. It’s enough of a signal that the company is planning to meet with the FDA to discuss next steps.
But for now, it’s another murky readout for a patient population waiting for a much-needed breakthrough. The company has yet to receive the full dataset, at which point it will do a more thorough scan of biomarker signals for neurodegeneration and additional posthoc analyses.
All told, Seelos said 31 patients took Relyvrio during the trial, “thus confounding results from this population,” according to a release. Amylyx’s drug was approved in September 2022 based on phase 2 data but its fate is in question after failing a subsequent phase 3 study. Company executives are mulling whether to pull the drug off the market.
In the last year, Seelos prioritized ALS as the primary use of SLS-005, pausing enrollment in a mid-stage trial for patients with spinocerebellar ataxia type 3 due to financial reasons. SLS-005 is an IV-administered form of trehalose, a nonreducing sugar commonly found in bacteria, fungi, yeast, insects, and plants. Seelos said that the low molecular weight disaccharide can stabilize misfolded proteins and activate autophagy in cells.
The biotech’s lead asset, SLS-002, is an intranasal form of ketamine in development to treat both PTSD and suicidal ideation in patients with major depression.
But the biotech will likely need to raise more money to continue development, having reported less than $3 million in cash to hand as of the end of 2023. In January, Seelos raised a $4 million direct offering and concurrent private placement but that money is set to be aimed in part at paying off interest payments on an outstanding convertible promissory note.