Challenges and solutions in the development of drugs for rare diseases
With around 7,000 identified conditions and more than 3 million people affected in France, rare diseases represent a medical field in their own right, characterized by specific needs in terms of diagnosis, monitoring, and treatment. Their low prevalence, clinical complexity, and lack of available data make the development of treatments particularly challenging.
This article explores the regulatory framework, the main challenges encountered, and the solutions being implemented to advance research and facilitate access to appropriate therapies.
Definition and key data
A rare disease is a condition that affects a small number of people and requires specialized care. In France, there are approximately 7,000 rare diseases, affecting more than 3 million patients, or nearly 4.5% of the population. Half of these diseases appear before the age of 5 and are responsible for around 10% of deaths between the ages of 1 and 5.
Nearly 80% of rare diseases are genetic in origin. In half of all cases, they cause motor, sensory, or intellectual impairment, and in 9% of cases, total loss of independence.
The term “orphan disease” applies to rare diseases for which there is no effective treatment.
Challenges in developing drugs for rare diseases
Small population size and methodological difficulties
The small number of patients affected by a rare disease is a major obstacle to research. It limits scientific visibility, access to funding, and the ability to conduct robust clinical trials. Prevalence of sometimes fewer than a few hundred cases complicates identification and inclusion. Clinical heterogeneity and the lack of data on natural history hinder the definition of relevant endpoints and weaken protocols.
The methodology of clinical trials is often based on small sample sizes, which limits the scope of the results and increases uncertainty about efficacy in real-world conditions.
Patient-specific issues and limitations of clinical trials
Many rare diseases affect children, which impose specific constraints in terms of ethics, protocols, and appropriate formulations. Clinical trials conducted on small populations do not always allow for the prediction of long-term effects or real-world efficacy at the time of Marketing Authorization. These methodological limitations complicate development and slow down access to treatments. They also undermine the economic attractiveness of the field, as companies have to bear high costs for an uncertain return on investment. This situation justifies the use of specific regulatory and financial support.
Role of stakeholders and need for collaboration
Approximately 61% of clinical trials are sponsored by the pharmaceutical industry, compared to 39% by non-commercial stakeholders, mainly academic institutions. Basic research provides scientific foundations, while companies are responsible for clinical and regulatory development. However, for many rare diseases, the knowledge base remains insufficient, which limits investment. Furthermore, information remains fragmented across different institutions, reducing its usefulness to stakeholders.
These constraints make structured collaboration between researchers, clinicians, patients, funders, and authorities essential. The combination of multidisciplinary skills is a prerequisite for advancing the development of orphan drugs.
The European regulatory framework
An incentive framework to encourage innovation
In order to support the development of drugs for rare diseases, the European Union introduced Orphan Drug Designation (ODD) in 2000. This applies when the prevalence is less than 5 per 10,000 inhabitants and the disease is serious or debilitating.
This designation provides access to several benefits: ten years of market exclusivity, tax reductions, subsidies, and free scientific advice. The EMA also offers the PRIME procedure, which facilitates early exchanges with the authorities. Finally, Marketing Authorization Applications (MAAs) may benefit from accelerated assessment or result in conditional Marketing Authorization or Marketing Authorization under exceptional circumstances, when not all clinical data can be provided.
Persistent constraints and the need for monitoring
While these measures speed up access to treatment, they do not remove regulatory requirements in terms of benefit/risk. Orphan drugs must demonstrate sufficient efficacy and safety despite sometimes limited clinical data. The authorities therefore impose enhanced risk management plans, post-authorization monitoring and, in some cases, additional real-world studies.
These constraints are intended to compensate for the uncertainties associated with small sample sizes and the difficulty of predicting efficacy in real-world conditions. Furthermore, the regulatory framework remains complex for project leaders, who must adapt their development strategy to the specific characteristics of each disease. This complexity justifies the need for specialized regulatory support, capable of anticipating the expectations of agencies, optimizing the choice of procedures, and securing interactions with health authorities.
Collaborative initiatives and the role of patients
Beyond the regulatory framework, the European Union has set up several collaborative programs designed to strengthen research and pool resources.
Among them, the European Joint Program on Rare Diseases (EJP RD) promotes the transition from basic research to clinical application, while the European Reference Networks (ERN) bring together more than 900 specialized units in 26 member states.
The ERICA consortium coordinates the clinical research activities of the ERNs, and infrastructures such as EATRIS and ECRIN support preclinical development and multinational trials.
Platforms such as Orphanet centralize knowledge and facilitate access to information, while the IRDiRC and EURORDIS strengthen international cooperation and the voice of patients.
These initiatives demonstrate the importance of a collective approach to overcoming data fragmentation and optimizing the development of orphan drugs.
Available solutions and levers
Natural History Studies (NHS)
Natural History Studies (NHS) describe the progression of a disease throughout the patient’s life in the absence of treatment. They trace the different phases of the disease, from the pre-symptomatic period to the advanced stages, and incorporate genetic, clinical, and environmental variables.
They play an essential role in rare diseases, enabling the characterization of phenotypes, the identification of patient subgroups, and the definition of appropriate endpoints for clinical trials. However, conducting these studies remains complex due to the small number of patients available and the dispersion of data.
Patient registries
Patient registries complement these studies by collecting clinical and epidemiological information in a structured manner. There are currently more than 700 rare disease registries in Europe (Orphanet). These tools facilitate recruitment for clinical trials, enable post-treatment follow-up, and document phenotypic variability and genotype-phenotype correlations.
They are therefore an essential tool for meeting regulatory requirements and strengthening research by providing a consistent and usable database at the European level.
The importance of strategic and regulatory support
The development of treatments for rare diseases relies on appropriate organization. Collaboration with patient associations provides essential data on disease progression, unmet needs, and therapeutic priorities, which can be incorporated into the design of clinical trials.
Early identification of reliable biomarkers is also crucial to understanding the disease, refining patient stratification, and guiding therapeutic strategies.
Finally, setting up a multidisciplinary team combining researchers, regulatory experts, market access specialists, and patient representatives helps to enhance the quality of development and optimize interactions with health authorities.
Conclusion
Rare diseases collectively affect millions of patients but lack therapeutic solutions. The constraints associated with low prevalence and lack of data are mitigated by a specific regulatory framework, including Orphan Drug Designation and accelerated procedures.
The use of registries, Natural History Studies, and international collaborations is now the preferred route for advancing research and accelerating the availability of treatments.
