Neurocrine Biosciences has presented the first head-to-head data comparing VMAT2 target occupancy between INGREZZA® (valbenazine) and AUSTEDO XR® (deutetrabenazine) at therapeutic doses. The results show a clear difference in target engagement.
INGREZZA achieved nearly double the VMAT2 occupancy, a marker linked to drug response in involuntary movement disorders.
Why VMAT2 Occupancy Matters?
VMAT2 inhibition is a validated mechanism in:
- Tardive dyskinesia (TD)
- Huntington’s disease (HD) chorea
Higher VMAT2 occupancy indicates stronger target engagement. This reduces excessive dopamine signaling that drives involuntary movements.
Head-to-Head Study Highlights
The study used PET imaging to measure VMAT2 occupancy after a single dose.
Key details:
- 8 participants
- Four PET scans per participant
- Therapeutic doses only
Primary Findings
- INGREZZA: ~76.5% VMAT2 occupancy
- AUSTEDO XR: ~38.3% VMAT2 occupancy
That is an approximate two-fold difference.
Estimated Steady-State VMAT2 Occupancy
|
Drug |
Dose |
Estimated VMAT2 Occupancy |
|
INGREZZA |
40mg |
83% |
|
INGREZZA |
80 mg |
92% |
|
AUSTEDO XR |
24 mg |
54% |
|
AUSTEDO XR |
48 mg |
70% |
Modeling based on pharmacokinetic exposure and EC50 values supported superior and sustained VMAT2 engagement with INGREZZA.
What Drives the Difference?
Neurocrine attributes the higher occupancy to pharmacology.
- INGREZZA produces a single high-affinity active metabolite
- AUSTEDO XR generates multiple metabolites, including some with lower VMAT2 affinity
This may explain differences in potency and clinical performance.
Clinical Relevance
According to Neurocrine Biosciences:
- Higher VMAT2 occupancy may support earlier and sustained efficacy
- Findings align with outcomes from multiple TD and HD chorea trials
- Both treatments were generally well tolerated, with safety profiles consistent with prior data
INGREZZA at a Glance
- FDA-approved for tardive dyskinesia and HD chorea
- Once-daily dosing, no titration required
- Available in capsule and sprinkle formulations
- Designed to selectively inhibit VMAT2, with minimal off-target activity
Bigger Picture
This head-to-head PET study adds mechanistic clarity to differences among VMAT2 inhibitors.
For clinicians and researchers, the data reinforce how target engagement, not just dose, shapes clinical outcomes in movement disorders.
