US-based biopharmaceutical firm resTORbio has commenced a Phase Ib/IIa clinical trial of its RTB101 candidate as a monotherapy or combination for the treatment of Parkinson’s disease.
Parkinson’s disease is a progressive neurodegenerative disorder known to impact nearly 7.5 million people globally.
RTB101 is an oral small molecule inhibitor of rapamycin complex 1 (TORC1). The candidate binds to the active site of mTOR on the TORC1 complex.
The randomised, double-blind, placebo-controlled Phase Ib/IIa trial is designed to assess the safety and tolerability of RTB101 alone or in combination with sirolimus in approximately 45 participants.
It will enrol mild Parkinson’s disease patients who are on standard-of-care therapy, irrespective of their glucocerebrosidase (GBA) mutation status.
Subjects will be randomised into five cohorts and administered with a 300mg dose of RTB101 alone or in combination with 2mg, 4mg or 6mg sirolimus.
The primary endpoint of the trial is safety and tolerability, while secondary endpoints include exposure in blood, plasma and cerebrospinal fluid (CSF).
The trial’s planned exploratory endpoints include biomarkers in plasma and cerebrospinal fluid (CSF) and different clinical assessments. Results from the trial are expected to be available next year.
resTORbio co-founder, president and CEO Chen Schor said: “We believe that TORC1 may be an important therapeutic target for several neurodegenerative diseases associated with aging, in which misfolded proteins aggregate and cause neuronal toxicity.
“Multiple preclinical models of PD have demonstrated the potential benefits of TORC1 inhibition, and intermittent TORC1 inhibition with a synergistic combination of RTB101 and sirolimus may serve as a promising approach for the treatment of PD.”
The combination of RTB101 and sirolimus is expected to trigger autophagy to eliminate protein aggregates in neurons, increasing lysosomal biogenesis and decreasing glucosylceramide (GL1) synthesis.