INGREZZA's Late-Life Breakthrough: Neurocrine Biosciences Poised to Capture a Growing Neurology Market

The neurology market is bracing for a seismic shift as Neurocrine Biosciences (NASDAQ: NBIX) continues to validate INGREZZA's transformative potential in older adults with tardive dyskinesia (TD). With mid-2025 clinical data reinforcing its efficacy in this vulnerable population, INGREZZA is emerging as a cornerstone therapy in a rapidly expanding market. For investors, this represents a rare opportunity to capitalize on a drug that's not only medically critical but also strategically positioned to dominate an underpenetrated segment of the TD landscape.

The Tardive Dyskinesia Crisis in Aging Populations

Tardive dyskinesia—a disabling condition marked by involuntary movements—impacts over 800,000 U.S. adults, with older patients disproportionately affected due to prolonged antipsychotic drug use. As the global population ages, this figure is projected to rise, particularly among individuals managing schizophrenia, bipolar disorder, or depression, where antipsychotics are often prescribed long-term. Yet TD remains underdiagnosed and undertreated, leaving millions without access to effective therapies. Neurocrine's clinical data now positions INGREZZA to fill this gap.

Phase 4 Trials: A Clinical Home Run for Older Adults

Recent trials have cemented INGREZZA's profile as a first-line therapy for elderly TD patients:

1. Randomized Withdrawal Study (NCT03891862): Patients who stayed on INGREZZA maintained significant improvements in quality-of-life metrics (EQ-5D-5L) and functional status (Sheehan Disability Scale) compared to those switched to placebo. These results are particularly compelling for older adults, who often face mobility and social isolation challenges exacerbated by TD.
2. KINECT-PRO™ Real-World Data: Demonstrated clinically meaningful reductions in TD severity using the Tardive Dyskinesia Impact Scale (TDIS™), a validated tool. The study also highlighted long-term safety, with no new risks identified in elderly patients.

These outcomes were showcased at major 2025 conferences, including the American Association of Nurse Practitioners (AANP), underscoring INGREZZA's growing acceptance in clinical practice.

Market Expansion: A Triple-Play Opportunity

1. Untapped Elderly Population: With 65+ adults accounting for ~30% of all TD cases, INGREZZA's safety and efficacy in this group opens a multi-billion-dollar market. Neurocrine's sprinkle formulation (INGREZZA SPRINKLE) further enhances accessibility for elderly patients with swallowing difficulties.
2. Global Penetration: While the U.S. FDA has already approved INGREZZA for TD and Huntington's chorea, international markets remain largely untapped. Neurocrine is well-positioned to replicate its U.S. success in Europe and Asia, where TD prevalence is similarly high.
3. Pharmacoeconomic Appeal: Data from the ISPOR conference highlighted disparities in TD diagnosis among Medicare patients. By improving quality-of-life metrics and reducing caregiver burden, INGREZZA could become a cost-effective solution for aging populations under Medicare/Medicaid, driving reimbursement and adoption.

Risks and Regulatory Tailwinds

While Neurocrine faces competition from generics and rivals like deutetrabenazine (Austedo), INGREZZA's differentiated profile—a selective VMAT2 inhibitor with no required dose titration—offers a compelling advantage. The FDA's recent support, including no new safety signals in elderly trials, further reduces regulatory uncertainty.

Investment Thesis: A Hidden Neurology Gem

At current valuations, NBIX remains underappreciated by the market. With a trailing P/E of 15.2x and a 5-year revenue CAGR of 22%, Neurocrine is pricing in modest growth expectations. However, the late-stage data for elderly patients could unlock a surge in prescriptions, especially as clinicians increasingly recognize TD's impact on functional outcomes.

Analysts estimate INGREZZA's peak sales could exceed $2 billion annually, driven by its dual indications and elderly population expansion. For investors, the stock's current price—down ~18% year-to-date amid sector-wide volatility—presents a buying opportunity ahead of potential catalysts:
- 2025 Q3: Updated Medicare claims data on TD diagnosis rates.
- 2025 Q4: Submission of KINECT-PRO's long-term safety data to the FDA.

Final Take: Buy the Dip, Harvest the Upside

Neurocrine Biosciences is at a pivotal juncture. Its late-stage clinical success in elderly TD patients, combined with a drug profile that's both safe and differentiated, positions INGREZZA to dominate a growing market. With a robust pipeline and underappreciated valuation, NBIX deserves a place in any portfolio targeting neurology's next wave of growth.

Investors who act now may secure a multi-bagger opportunity as INGREZZA solidifies its role as a standard of care for an aging population's unmet needs.