PTC reports positive Phase II Huntington’s data, FDA lifts partial clinical hold

Published: Jun 20, 2024

By Tyler Patchen

BioSpace

PTC Therapeutics announced Thursday that its Huntington’s disease candidate PTC518 is no longer subject to an FDA partial clinical hold after it showed positive interim results from a Phase II study.

Interim results from the PIVOT-HD trial of PTC518 in Huntington’s disease (HD) patients demonstrated the oral small molecule lowered mutant huntingtin (mHTT) protein levels in the blood and cerebrospinal fluid (CSF). PTC also touted “favorable trends” shown on several HD clinical assessments, including Total Motor Score and Composite Unified Huntington’s Disease Rating Scale. The candidate was also found to be safe and well-tolerated after 12 months of treatment.

PTC518 lowered mHTT levels in the blood by 22% and 43% at the 5mg and 10mg doses, respectively. For the CSF metric, dose-dependent mHTT was reduced by 21% at the 5mg dose and 43% at the 10mg dosage. In slowing the progression of motor symptoms, a worsening by 2.0 points at the 5mg dosage amount was recorded, while a 1.3 point worsening was found at the 10mg level. By comparison, patients taking the placebo had a worsening of 4.9 points.

“The evidence of both CNS biomarker and early clinical effects at month 12 along with the continued favorable tolerability profile supports the promise of PTC518 to address the need for an effective and safe disease-modifying therapy for patients living with Huntington’s disease,” PTC CEO Matthew Klein said in a statement.

PTC reported that the FDA lifted its partial clinical hold on the candidate based on a data review. In October 2022, the FDA put the program on pause after the agency requested more data to support PTC518’s dosing and duration proposed in the 12-month study, the company told BioSpace at the time. However, PTC continued to enroll patients in other locations worldwide.

Thursday’s positive results for PTC come as other players in the Huntington’s space continue to struggle. Earlier this month, Sage Therapeutics announced that its oral NMDA receptor dalzanemdor had a slight numerical improvement in a Phase II Huntington’s trial. However, no data were provided and in a note to investors William Blair analysts said that the results were “underwhelming” and they remain cautious about Sage’s candidate as the small changes are not seen as “definitive.”

Tyler Patchen is a staff writer at BioSpace. You can reach him at [email protected]. Follow him on LinkedIn. 

Source: BioSpace