Rare diseases, also known as orphan diseases, affect an estimated 300 million people worldwide, yet each individual condition impacts a relatively small patient population, typically fewer than 1 in 2,000 individuals in the European Union or similar thresholds globally. Despite individual rarity, the combined burden is substantial.

Even though there is a growing interest in orphan drug development, many pharmaceutical companies remain cautious about investing in rare diseases due to significant scientific, financial, and operational challenges. The small patient populations inherent to rare diseases make it difficult to conduct robust clinical trials and limit the potential for commercial return. The pathway to regulatory approval is often complex due to limited natural history data, lack of standardised clinical endpoints, and challenges in trial recruitment. The high cost of research and development, combined with increasing scrutiny from payers over cost-effectiveness and long-term value, mean that many companies prioritise broader indications with more predictable pipelines and larger markets, where return on investment is more assured.