How Pediatric Exclusivity and Priority Review Vouchers Accelerate Rare Disease Drug Development

Why Pediatric Incentives Are Critical in Rare Disease Drug Development

Over 50% of rare diseases affect children, yet pediatric drug development often lags due to ethical complexities, limited commercial return, and small patient populations. To address this, the U.S. Food and Drug Administration (FDA) has introduced specific regulatory incentives to promote research in rare pediatric diseases, including Pediatric Exclusivity and the Rare Pediatric Disease Priority Review Voucher (PRV) program.

These mechanisms reward sponsors for conducting pediatric studies, accelerating access to life-saving therapies while offering tangible commercial and regulatory benefits. For sponsors developing orphan-designated or ultra-rare pediatric therapies, these programs can provide both strategic leverage and financial returns.

Pediatric Exclusivity: What It Is and How It Works

Authorized under the Best Pharmaceuticals for Children Act (BPCA), pediatric exclusivity is a 6-month extension of existing regulatory exclusivity (e.g., Orphan Drug Exclusivity, New Chemical Entity, or patent protection). This incentive is granted when a sponsor completes FDA-requested studies under a Written Request (WR) for pediatric use.

Key Points:

• Pediatric studies must address safety and/or efficacy in the relevant age group (neonates to adolescents)
• The studies must follow protocols outlined in the FDA’s Written Request
• Upon acceptance, 6 months is added to all forms of marketing exclusivity for that drug

This extension applies even if the pediatric indication is not ultimately approved, making it a powerful incentive for broader product lifecycle management.

Rare Pediatric Disease Priority Review Voucher (PRV): Overview and Eligibility

The PRV program rewards sponsors that develop treatments for serious or life-threatening rare pediatric diseases. Upon approval of a qualifying application, the sponsor receives a transferable voucher that entitles the holder to priority review (6-month review timeline) of a future drug or biologic application.

Eligibility Criteria:

• The disease must primarily affect individuals under 18 years old
• The condition must be rare (<200,000 patients in the U.S.)
• The drug must represent a new active ingredient (not a label extension)

Priority Review Vouchers are transferable and monetizable, with past transactions exceeding $100 million in value. For smaller biotech companies, selling a PRV can provide non-dilutive capital to fund additional trials.

Examples of Drugs Awarded Pediatric PRVs

Since its inception in 2012, the PRV program has accelerated the development of therapies for numerous pediatric rare diseases. Examples include:

• Vimizim (elosulfase alfa) for Morquio A syndrome – PRV sold for $67 million
• Luxturna (voretigene neparvovec) for inherited retinal dystrophy – PRV retained by sponsor
• Brineura (cerliponase alfa) for CLN2 Batten disease – PRV used for follow-up asset

The financial value of PRVs has supported clinical expansion, commercialization infrastructure, and investor confidence in otherwise high-risk pipelines.

Comparison: Pediatric Exclusivity vs Priority Review Voucher

Savvy sponsors often pursue both, especially when developing novel pediatric therapies with orphan designation and unmet need alignment.

Regulatory Considerations and Best Practices

To maximize benefit and ensure compliance:

• Engage the FDA early through a Pediatric Study Plan (PSP)
• Request Written Request documentation and negotiate feasible study designs
• For PRVs, ensure your target indication meets the statutory definition under Section 529 of the FD&C Act
• Include PRV language in the initial NDA/BLA cover letter

Sponsors should consult CDER’s Rare Diseases Program or CBER’s Office of Tissues and Advanced Therapies for guidance tailored to their product type (small molecule vs biologic vs gene therapy).

Commercial Implications and Funding Opportunities

Pediatric incentives offer not just regulatory advantages, but strategic financial benefits as well:

• 6-month exclusivity can translate to hundreds of millions in additional revenue for blockbuster drugs
• PRV sales provide immediate capital to advance other pipeline assets
• Investors view these incentives as de-risking mechanisms, often improving access to capital

In rare pediatric conditions with short survival timelines, these incentives also create urgency within the company—often speeding internal decision-making and resource allocation.

Case Study: Pediatric Exclusivity in a Spinal Muscular Atrophy (SMA) Drug

The developer of Spinraza (nusinersen) submitted post-marketing pediatric studies as requested by the FDA under BPCA. Upon completion, the FDA granted an additional 6 months of exclusivity, which extended the drug’s monopoly despite the presence of competing gene therapies. The additional time allowed for continued market leadership and justified pricing discussions with global payers.

Conclusion: Incentives That Make a Measurable Difference

Pediatric Exclusivity and Priority Review Vouchers are vital components of the rare pediatric drug development ecosystem. When strategically leveraged, they help sponsors recoup investment, fund innovation, and—most importantly—accelerate the delivery of therapies to the most vulnerable patient populations. As the regulatory landscape continues to evolve, these incentives remain key enablers for turning rare pediatric treatments into commercial and clinical realities.

Accelerating Rare Disease Therapies Through Fast Track and Breakthrough Designations

The Need for Expedited Development in Rare Diseases

Rare diseases—often debilitating, progressive, and life-threatening—affect millions worldwide, yet most lack approved treatments. Traditional drug development timelines spanning 10–15 years are incompatible with the urgent needs of rare disease patients. Recognizing this, regulatory agencies like the U.S. Food and Drug Administration (FDA) have developed expedited pathways to speed up access to safe and effective therapies for serious and life-threatening conditions with unmet medical need.

Two of the most impactful tools in this regulatory toolkit are Fast Track Designation and Breakthrough Therapy Designation. Both offer significant benefits to developers of rare disease therapies—especially when combined with Orphan Drug Designation, Accelerated Approval, or Priority Review.

Fast Track Designation: Overview and Eligibility

Fast Track is a formal FDA program designed to facilitate the development and expedite the review of drugs that treat serious conditions and address unmet medical needs.

Eligibility Criteria:

• The drug must treat a serious or life-threatening condition (e.g., Duchenne muscular dystrophy, cystic fibrosis, Batten disease)
• There must be no existing therapy, or the drug must show advantages over available treatments

Key Benefits:

• More frequent meetings and written communication with the FDA
• Rolling submission of the New Drug Application (NDA) or Biologics License Application (BLA)
• Eligibility for Priority Review and Accelerated Approval if relevant criteria are met

Example: A sponsor developing a gene therapy for Leber congenital amaurosis received Fast Track designation based on early data showing significant vision improvement compared to supportive care.

Breakthrough Therapy Designation: Overview and Criteria

Breakthrough Therapy Designation (BTD) is an even more selective FDA program intended for drugs that may offer substantial improvement over existing therapies on one or more clinically significant endpoints.

Eligibility Criteria:

• Preliminary clinical evidence must demonstrate substantial improvement over available therapy
• Applies to serious or life-threatening conditions

Key Benefits:

• All Fast Track features
• Intensive FDA guidance on efficient drug development
• Organizational commitment from FDA senior managers
• Eligibility for rolling review and other expedited pathways

Example: Exondys 51 (eteplirsen) for Duchenne muscular dystrophy received BTD after early clinical evidence showed dystrophin expression—a surrogate endpoint associated with slowed disease progression.

Key Differences: Fast Track vs Breakthrough Therapy

While both programs offer expedited pathways, they differ primarily in the strength of evidence required and level of FDA engagement:

Both designations can be requested at the IND stage or anytime during clinical development. Sponsors are encouraged to submit robust data packages and justify the designation criteria in their request letters.

Regulatory Submission and Review Process

Once granted, Fast Track and Breakthrough Therapy designations unlock a more flexible, responsive, and efficient regulatory dialogue. Typical milestones include:

• Type B meetings with FDA to align on trial design and endpoints
• Protocol Agreement letters under Special Protocol Assessment (SPA)
• Rolling NDA/BLA submissions, allowing early modules to be reviewed in advance
• Post-marketing study expectations clarified early in development

Proactive engagement with the FDA significantly reduces the risk of costly missteps, such as inadequate trial powering or suboptimal endpoint selection.

Benefits for Rare Disease Developers

Fast Track and Breakthrough Therapy designations are particularly valuable in the rare disease landscape because:

• Clinical trials in rare diseases often rely on small sample sizes or surrogate endpoints
• There are frequently no established therapies to serve as comparators
• Regulatory flexibility and speed are vital for conditions with early mortality or severe morbidity

By receiving these designations, sponsors gain credibility with investors, attract partnerships, and build momentum for rare disease programs that would otherwise struggle to reach commercialization.

Combining with Other Rare Disease Incentives

Expedited designations are most powerful when combined with other incentives such as:

• Orphan Drug Designation: Grants 7 years (US) or 10 years (EU) of market exclusivity
• Rare Pediatric Disease Priority Review Vouchers (PRVs): Transferable and potentially worth over $100 million
• Accelerated Approval: Approval based on surrogate endpoints with post-marketing requirements

Case in point: A treatment for CLN2 disease received orphan, breakthrough, and priority review designations—leading to marketing approval within 4 years of first-in-human dosing.

Global Perspectives: EMA’s PRIME vs FDA’s Programs

The European Medicines Agency (EMA) offers similar expedited pathways through its PRIME (PRIority MEdicines) scheme. While not identical to Fast Track or Breakthrough Therapy, PRIME provides:

• Early scientific advice and dialogue
• Dedicated contact points
• Eligibility for accelerated assessment

Sponsors developing therapies for rare diseases may benefit from parallel applications with both the FDA and EMA to ensure harmonized development strategies across regions.

Best Practices for Sponsors Seeking Expedited Designations

To improve the likelihood of receiving Fast Track or Breakthrough Therapy status:

• Engage FDA early through pre-IND or INTERACT meetings
• Submit robust, data-driven designation request letters
• Clearly articulate how the therapy addresses unmet need or improves clinical outcomes
• Prepare supporting material such as investigator brochures, preliminary datasets, and comparison to current standard of care

Use real-world evidence (RWE), natural history studies, and patient-reported outcomes (PROs) to strengthen your submission—especially in ultra-rare populations.

Conclusion: Empowering Rare Disease Innovation Through Expedited Pathways

Fast Track and Breakthrough Therapy designations are transformative tools for rare disease developers. They not only accelerate timelines and regulatory interactions but also signal therapeutic potential to the broader scientific and investment communities. When used strategically and ethically, these designations reduce the time between discovery and patient access—helping bring hope to those with the greatest need.