On 5 May 2025, PTC Therapeutics shared a press release reporting results from the PIVOT-HD study of PTC518 (votoplam), a small molecule splicing modifier. This Phase 2, 12-month trial assessed the pharmacodynamic effect and safety of PTC518 at 5 mg and 10 mg compared to placebo in participants defined as HD-ISS Stage 2 or Stage 3. The primary endpoint of reduction in blood Huntingtin (HTT) protein levels at Week 12 was met, while PTC518 was also safe and well-tolerated. The 12-month data from HD-ISS Stage 2 participants were consistent with the previously reported dose-dependent lowering of HTT protein and dose-dependent trends across clinical scales. However, this was not apparent for Stage 3 participants, suggesting that treatment response to PTC518 may differ according to disease stage.

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