On 7 December, Neurocrine Biosciences announced positive topline results from KINECT-HD (NCT04102579), a Phase III clinical trial of Ingrezza (valbenazine), a selective vesicular monoamine transporter 2 (VMAT2) inhibitor, in the treatment of adults with chorea (involuntary muscle movements) associated with Huntington’s disease (HD). Ingrezza was first approved by the US Food and Drug Administration (FDA) for tardive dyskinesia in 2017 and Neurocrine is now planning to submit a supplemental new drug application in HD chorea. GlobalData expects that this newly published data will propel Ingrezza into a dominant position in the HD market due to its convenient once-daily dosing regimen and improved safety profile. Compared with available competitors from the same therapeutic class, Ingrezza requires less frequent dosing and does not pose the risk of increased depression and suicidal ideation. Given Ingrezza’s competitive advantage and the sparseness of the US HD therapeutics market, Ingrezza is forecast to generate strong sales of $326m for HD in the US until 2030. The drug is likely to seize significant market share from its main competitor and current market leader, Teva’s Austedo (deutetrabenazine).

KINECT-HD was a randomised, double-blind, placebo-controlled study conducted in the US that assessed Ingrezza’s efficacy, safety and tolerability among 120 patients with HD chorea. The study met its primary endpoint of reducing the symptoms of chorea, assessed by the baseline change in the Unified Huntington’s Disease Rating Scale (UHDRS) and the total maximal chorea (TMC) score. Patients who were on Ingrezza achieved a placebo-adjusted mean reduction in the TMC score by 3.2 units (p < 0.0001) at weeks ten and 12, in addition to improvements across multiple secondary endpoints. The study showed that Ingrezza does not worsen suicidality in patients, which is a key benefit as the development of psychiatric and cognitive symptoms is a common comorbidity in HD patients.

Key opinion leaders (KOLs) interviewed by GlobalData highlighted that one of the most pressing unmet needs in HD is for improved symptomatic treatments that can demonstrate superior clinical efficacy and/or safety to the current standard of care. Chorea occurs in more than 80% of patients with adult-onset HD and is not effectively managed by current treatment options. Because of this, KOLs believe that Ingrezza will be a welcome addition to the HD armamentarium and will fulfil a key unmet need.

At present, there are only two drugs approved in the US for the treatment of chorea associated with HD, namely Bausch’s Xenazine (tetrabenazine) and Teva’s Austedo. Both drugs belong to the same therapeutic class of VMAT2 inhibitors as Ingrezza. In addition, several generic versions exist for tetrabenazine in the US, offering comparable efficacy at lower costs. Despite this, tetrabenazine generics may not be preferred by many patients as they require dosing three times a day and have a boxed warning on the label regarding the increased risk of suicidality. These issues directly affect patient compliance and subsequently limit the utility of those treatments. As a result, Ingrezza is more likely to compete for new patients against Teva’s Austedo, which has been adopted by physicians since its launch in 2017 owing to the convenience of twice-daily dosing. Similar to tetrabenazine, however, Austedo also has a boxed warning regarding the risks of depression and suicidality. GlobalData believes the clinical advantages that Ingrezza has shown so far in trials will allow it to move to the front lines of treatment for HD chorea and gain significant market share upon its 2023 US launch.