The reason isn't lack of investment. It's structural. Small, scattered patient populations make site identification, patient access, and operational planning fundamentally different from mainstream trial design.
Many sponsors apply conventional feasibility playbooks to rare disease programs and watch enrollment stall. This guide breaks down what actually works: how to identify the right sites, remove access barriers for patients, and plan operations that survive contact with reality.
Key Takeaways
- Build site networks around disease expertise and referral pathways, not raw patient volume
- Plan for travel burden, diagnostic delay, and caregiver load in the protocol—not after activation
- Add decentralized visit options and lock regulatory strategy early to protect timelines
- Choose a rare-disease-experienced global CRO to compress start-up and raise enrollment odds
Understanding the Unique Landscape of Rare Disease Trials
There are more than 7,000 identified rare and neglected diseases with a known molecular cause, but only about 500 have an approved treatment, according to the NIH. That leaves the vast majority of patients without an approved option.
Before patients even reach a trial, they face the diagnostic odyssey. The EveryLife Foundation found that diagnosis takes more than six years on average, involving nearly 17 doctor visits and hospitalizations. By the time a patient is correctly diagnosed, they've often lost years of eligibility for early-intervention studies.
Common Structural Challenges
Rare disease programs run into problems that standard trial models weren't built for:
- Thin natural history data — few standardized endpoints exist to measure disease progression
- Divergent regulatory expectations — FDA and EMA guidance diverges enough that protocols often need dual-compliant design from the outset
- High termination rates — 30.2% of 659 rare disease trials were discontinued; insufficient accrual drove 31.2% of those stops
That last statistic should reframe how sponsors think about feasibility. Recruitment isn't a downstream risk to manage. It's the primary threat to the entire program.
Site Identification Strategies for Rare Disease Trials
Standard feasibility metrics (historical enrollment volume, general site experience, geographic convenience) do not translate to rare disease work. A site with strong enrollment numbers on common indications may have zero molecularly confirmed patients for an ultra-rare protocol.
What matters instead:
- Proximity to disease-specific centers of excellence
- Established relationships with key opinion leaders (KOLs) in that condition
- Referral pathways from genetic counselors and specialty diagnostic labs
- Willingness to support hybrid visit schedules
NORD's Rare Disease Centers of Excellence network is a useful model here: it concentrates specialist expertise and patient access in designated centers rather than spreading thin across generalist sites.
Building a Global, Multi-Regional Site Network
A single-country site list rarely provides enough eligible patients for adequate statistical power. Expanding across regions changes that math substantially.
This is where local regulatory and cultural expertise becomes non-negotiable, especially in emerging or underserved markets.
DRK Research Solutions operates across Europe, the Middle East, Asia, Africa, and the Americas, with local teams in markets such as Pakistan, Malaysia, Nepal, and the UAE. Those regions are often overlooked in rare disease feasibility planning, yet they include treatment-naive patient populations that single-country networks rarely reach.
Supporting Clinically-Naive Sites
Expanding into new regions often means working with sites that have never run a rare disease protocol. These sites typically need:
- Extended GCP training tailored to complex, resource-intensive protocols
- Systems support for eCRF, edit checks, and data capture unfamiliar to the site
- Protocol education covering rare disease-specific procedures, biomarker handling, and eligibility nuance
A hybrid on-site/remote monitoring model helps under-resourced sites stay compliant without requiring a full-time CRA presence for every visit.
Improving Patient Access and Recruitment
Distance is one of the biggest hidden disqualifiers in rare disease trials. A 2019 EveryLife survey found that 39% of respondents needed to travel 60 or more miles for expert care related to their condition. For families already managing a complex diagnosis, that burden can eliminate participation entirely.
Ways to reduce this barrier:
- Partner with disease-specific registries and advocacy groups such as the Cystic Fibrosis Foundation Patient Registry and the Duchenne Registry
- Offer travel and logistics support so distance isn't a disqualifying factor
- Add decentralized elements (telehealth, eCOA, home health visits) to cut required in-person trips
- Design pediatric protocols around caregivers, since nearly 75% of rare diseases present in childhood
Decentralized approaches aren't a cure-all. A 2023 DIA working group review notes that virtual participation can improve recruitment and retention, yet hybrid models still need strong centralized monitoring when sites see patients less often. Plan oversight and data flows for that reduced direct access from day one.
Operational Planning for Rare Disease Trial Success
Getting patients into the trial is only half the job. Keeping the study running for years without losing participants is the harder half.
Start with the protocol itself. Overly restrictive inclusion/exclusion criteria are a common, and avoidable, cause of enrollment failure. Early, collaborative review between sponsors and sites helps catch criteria that look rigorous on paper but eliminate half the eligible population in practice.
Then plan for the resource intensity. Rare disease protocols often demand:
- Specialized staff training and equipment not typically stocked at general sites
- Contingency plans for supply chain delays affecting single-source investigational products
- Backup diagnostic capacity when local labs can't run required assays
Retention matters as much as recruitment. Multi-year studies hinge on relationship-building:
- Flexible scheduling around school, work, and caregiver constraints
- Consistent, empathetic communication from the same study staff
- Proactive check-ins rather than reactive contact only at visit windows
Long-running rare disease programs also need evidence strategies that reduce operational risk. FDA's 2019 draft guidance notes that natural history data, often missing entirely for rare conditions, can support both trial design and regulatory submissions.
Expanded access programs (EAPs) complement this by generating real-world safety data alongside the formal study. Sponsors gain an additional evidence stream without competing for trial slots.
Choosing the Right Global CRO Partner for Rare Disease Studies
Not every CRO is built for this work. When evaluating a partner for a rare disease program, look for:
- Therapeutic-area experience specific to the disease category, not just general rare disease exposure
- Regulatory fluency across FDA, EMA, and other relevant agencies
- Established site and KOL relationships, not a cold-start feasibility process
- Operational flexibility to accommodate hybrid visits, caregiver scheduling, and protocol amendments
DRK Research Solutions was built with a different starting point than most CROs. The company began as a patient advocacy organization before evolving into a full-service CRO, and that heritage still shapes how it approaches trial design and site selection.
DRK's network spans Europe, the Middle East, Asia, Africa, and the Americas, with particular strength in underserved and low- and middle-income country (LMIC) markets. These are regions where rare disease patient populations are often available but historically left untapped by conventional CROs.
Paired with end-to-end CRO support—from protocol design and site identification through study conduct and closeout—DRK gives sponsors one accountable partner across the development lifecycle instead of a patchwork of vendors.
Frequently Asked Questions
What is the NORD List of rare diseases?
NORD’s A-Z Rare Disease Database covers more than 1,400 conditions, including symptoms, diagnosis, treatment, and research resources. Patients, clinicians, and researchers use it for reference and study prioritization.
What disease has the most clinical trials?
Oncology indications collectively have the most registered clinical trials overall. Within rare disease research, higher-prevalence conditions like cystic fibrosis tend to have far more studies than ultra-rare conditions.
How long does it typically take to diagnose a rare disease?
Patients often wait more than six years and undergo nearly 17 medical visits before receiving an accurate diagnosis. This delay compounds recruitment challenges since eligible patients simply aren't identified in time.
Why do many rare disease trials fail to complete enrollment?
Small eligible populations, overly strict inclusion criteria, and geographic or travel burden are the leading causes. A 2019 analysis found insufficient patient accrual was the top reason for trial discontinuation.
What role do patient advocacy groups play in rare disease trials?
They support recruitment through registries and community networks and raise trial awareness among patients who might otherwise never hear about studies. Their involvement also lends credibility that improves patient trust and participation.
Are decentralized trial models effective for rare disease research?
Hybrid and decentralized approaches reduce patient burden and are increasingly adopted for rare disease studies. However, severe conditions often still require in-clinic oversight that full decentralization can't replace.
