Rare disease clinical trials factsheet

Rare disease clinical trials factsheet

It is estimated that 475 million people worldwide are affected by a rare disease.

Drug development for rare diseases involves significant challenges above and beyond those encountered in large trials for more common diseases. Partnering with Cromos Pharma means working with an international CRO with a strong track record in innovative trial design, exceptional multi-country patient recruitment and proven regulatory expertise.


The definition of rare diseases varies according to country.

In the US, a disease is considered rare and eligible to qualify for Orphan Designation if it affects less than 200,000 people in the United States. The National Human Genome Research Institute states that over 6,800 rare diseases affect a total of 25-30 million Americans.


In the EU, a rare disease is defined as a condition that affects no more than 1 person in 2,000. In the EU it is estimated that 5,000-8,000 distinct rare diseases affect 6-8% of the EU population i.e., between 27 and 36 million people.


Clinical trials involving rare diseases involve a unique set of scientific and operational challenges:

  • Limited pool of eligible patients
  • Wide geographical spread of study subjects and Investigators
  • Large heterogeneity in patient populations with different phenotypes and various disease pathophysiology
  • Lack of preceding clinical trials to establish a baseline standard for study execution
  • Large heterogeneity in treatment effects
  • Uncertainty in regulatory practice and various regulatory requirements in each country of operations


At Cromos Pharma we have extensive experience in managing all aspects of clinical trials for rare diseases. We take an innovative and flexible approach to ensure the success of our sponsors’ rare disease clinical projects. We do this by:

  • Understanding patient pathways to allow us to effectively identify and recruit patients
  • Leveraging our extensive site and investigator network to identify the optimal sites and staff
  • Providing ongoing monitoring and support to sites
  • Employing effective strategies to retain patients throughout studies

In the last 16 years, Cromos Pharma has contributed to the analysis, design, management and/or conduct of 20+ studies in rare diseases, covering Phases II to IV, including but not limited to:

  • Autism spectrum disorders
  • Bulimia nervosa
  • Congenital afibrinogenemia
  • Glioblastoma
  • Growth hormone deficiency (GHD)
  • Haemophilia A
  • Haemophilia B
  • Hereditary angioedema
  • Ménière’s disease
  • Niemann-Pick disease Type C
  • February 2022
  • Retinitis pigmentosa
  • Sjögren-Larsson syndrome
  • Von Willebrand’s Disease
  • X-linked adrenomyeloneuropathy


Cromos Pharma is a US-based, international contract research organization delivering fully integrated clinical research solutions, in all trial phases, across a wide range  of therapeutic indications. Our expert team, comprised of 95% MDs, has extensive expertise in study design, medical writing, regulatory affairs, site management, patient recruitment and data management.

Cromos Pharma has experience in delivering success in a wide range of trial types, from biosimilars and generics, to successfully managing trials of novel therapeutics in a wide range of clinical indications. Our team provides full-service solutions to international pharma and biotech companies in high-recruiting regions, assuring exceptional data quality. Cromos Pharma combines global expertise with in-depth experience and knowledge in the US, Central and Eastern Europe, Central Asia, Republic of Georgia, and Türkiye to offer exceptional patient recruitment. Our team has met or reduced enrollment timelines in 95% of conducted trials. 


  • 300+ clinical trials conducted in 70+ indications
  • 40,000+ patients enrolled from nearly 2,500 trial sites
  • Full professional liability coverage from Lloyd’s of London
  • Extremely short startup timelines
  • Regulatory inspections and audits that attest to the highest quality of data: FDA in 2017, EMA in 2019
  • Expertise in innovative, generics and biosimilar global studies (NDAs, ANDAs, BLAs, 505b2)
  • Unparalleled patient recruitment – our team met or shortened project timelines in 95% of conducted trials
  • Thorough proposals & accurate planning (avg. <1 change order/project)
  • Personal involvement of Executive Team
  • Team continuity (low turnover <5%)
  • Local PMs with specialist regional knowledge



Our unique risk sharing program: client reimburses Cromos Pharma only for enrolled patients and not for dormant, non-recruiting sites. If we don’t recruit – you don’t pay.


Selection of the optimal path forward, including country/venue strategy- and site-selection within the recommended venues.


Our team of experts has years of experience successfully working with the FDA, EMA and with the ex-US regulators.


By adding sites and utilizing our referral networks in CEE we recruit at 2-3X the industry average.


We provide comprehensive and collaborative rescue plans to ensure original investments yield a return and that studies are efficiently concluded.


The welfare of our patients is our first priority. We make sure that they have a direct line of communication to both the investigators and to our research team.


Our Quality Management System is built upon Quality by Design (QbD) principles that include integrated planning, quality agreements tailored to the project, real-time project risk-based analysis and data analytics-driven targeted monitoring.

Learn more about Cromos Pharma’s Orphan Drug and Rare Disease Expertise here

Read our PDF here

If you would like to find out more about how Cromos Pharma can support your next projects email bd@cromospharma.com.




To arrange an introductory meeting and find out how our experience can benefit your next clinical project.