The New Era of Rare Disease Drug Development: Trends to Watch

The FDA approved 46 new drugs in 2025 from its Center for Drug Evaluation and Research. 50% of these were orphan drugs, those made for rare diseases. Over 70% passed through one or more of the expedited pathways. It's not a symbolic figure, it's a warning that rare disease has come to the fore and is now the strategic focus of pharma R&D.

The need to know where this space is going is not a necessity for pharmaceutical companies, biotechnology firms, and CROs – it is a requirement. It is essential to compete.

Why Rare Disease Is No Longer a Side Bet in Pharma R&D

Economics have changed in an insurmountable manner. The proportion of orphan drugs, or those developed for rare diseases, is expected to make up more than 21% of global sales of prescription pharmaceuticals by 2032, compared to 15% in 2022. In absolute numbers, it's worth over $400 billion of revenue from a segment that wasn't deemed worthy of a scale strategy.

It is especially insightful to look at their deal activity. Evaluate Pharma's 2026 Orphan Drug Report shows that all ten of the forecasted orphan products for 2032 are either acquired or in-licensed. The rare disease pipeline intelligence is not only an R&D function, it's a business development function. It is companies who identify the brightest talent who win the licensing and M&A deals.

The Rare Disease Clinical Trials market is expanding rapidly, and by 2025, market value will be $13.3 billion and it is projected to reach $21.34 billion by 2030 with a CAGR of 10.1%. The growth is being fueled by the incentive for orphan drugs, the strengthening of trial networks across the globe, the use of artificial intelligence for study optimization and a general trend of regulatory reform that is making the development process much more navigable than it was just five years ago.

The message is loud and clear: Rare disease is no longer a charitable enterprise at the fringe of a company's portfolio. It's becoming the place where the richest science — and most critical resources — are being developed.

How the Clinical Drug Development Phases Work Differently for Rare Diseases

Each of the clinical phases of drug development is different for rare diseases, as detailed below.The following is a description of how each of the clinical phases of drug development is different for rare diseases.

It's helpful to know what the typical clinical drug development process is, and how it differs for rare diseases.

There are five steps in the drug development process:

Phase 0 — Exploratory, sub-therapeutic doses are administered to a very small number of subjects to gain a basic understanding of the pharmacokinetics of the drug

Phase I — Initial human safety testing with typically 20-80 healthy volunteers or patients

Phase II — Efficacy signals and dose-finding (typically 100-300 patients).

Phase III — Confirmatory trials (large scale studies of thousands of patients at multiple locations)

Phase IV — Post-marketing surveillance after approval

If there are, say, 3,000 people around the world who have this rare disease, it is simply impractical to conduct a Phase III trial on this number of people. There's no such patient population. If you did the same even if you recruited all the eligible patients in the world, you may only have 200 patients in the study.

This is a reason for the unique way that rare diseases are being approached in the phases of new drug development.

Many times, Phase I and Phase II trials are grouped together as a Phase I/II study. To get the best statistical efficiency out of a small number of subjects, the trial design is adaptable, meaning it can be changed as the study goes on, depending on the data received. Traditional clinical outcomes (which would take years to observe) are replaced by surrogate endpoints (biological markers that are reasonably likely to predict clinical benefit). And single-arm studies, comparing against historical natural history data instead of a placebo control group, have become common where it just isn't possible or ethical to conduct a randomized controlled trial.

This framework is official thanks to FDA's Rare Disease Evidence Principles (RDEP) announced in September 2025. With diseases that impact less than 1,000 patients in the United States, sponsors now have the chance to engage with the FDA prior to the start of a pivotal trial to clarify which evidence will be necessary for approval. It's a collaborative process that helps eliminate much of the uncertainty that has plagued rare disease development in the past.

It is a huge deal when a pharma or biotech team is following pipelines. A rare disease program can achieve NDA filing in a much shorter period of time than a cardiovascular or metabolic disease. Blink and you've missed the window.

New FDA Pathways Are Reshaping the Orphan Drug Playbook

One of the biggest growth drivers has been regulatory reform and the speed of such reform picked up a lot in 2025 and early 2026.

Here are some of the fundamental pathways to consider right now:

Orphan Drug Designation (ODD) is the basic encouragement for the development of rare diseases. In the USA it is used for diseases that affect less than 200,000 people. It includes 7 years market exclusivity, tax incentives for clinical trial costs, and FDA user fees waived. The threshold in Europe is less than 5 per 10,000 population.

Breakthrough Therapy Designation (BTA) is for drugs that have some preliminary evidence of substantial improvement over existing drugs in development. Accelerated FDA guidance during its development process (a fast track for drugs that have good early data).

Fast Track Designation (FTA)  provides increased opportunities for FDA meetings and rolling review, where sponsors can submit completed portions of their NDA before the final product is completed.

Accelerated Approval is a mechanism that enables drugs to be approved using surrogate endpoints, which are not clinical endpoints, such as survival, but rather other endpoints that are clinically meaningful. This is especially useful for ultra-rare diseases where measuring hard endpoints (such as survival) would take a long time. Post-marketing confirmatory trials are necessary to demonstrate clinical benefit.

The next big additions were made in 2025 and 2026. In November 2025, the FDA published the Plausible Mechanism Pathway, a guidance document that will enable gene editing and RNA-based therapeutics to be approved for ultra-rare diseases without the need for large randomized clinical trials where one is not feasible due to a plausible mechanism of action. This was followed in February 2026 by formal draft guidance by FDA regarding individualized therapies such as genome editing and RNA therapeutics such as antisense oligonucleotides that create a clear regulatory framework for therapies for a few patients, or even one patient.

This is a worthwhile note on the last point. The FDA is now establishing a regulatory framework for treatments for ‘one person.’ This represents the significant change of the rare disease picture at its core.

Business Development and Pipeline teams use these designations as indicators. While a company has now demonstrated business interest and confidence in the regulations, by declaring a BTA or ODD at Phase I. The first step in intelligence work in this domain is to follow those signals through a selected collection of trials, which includes indication, phase, sponsor and regulatory status.

The Technologies Driving the Next Wave

Science is meeting the need. The future of rare disease drug development lies in three technology trends.

The promise has become reality for gene and cell therapy. The first personalized in-vivo CRISPR base-editing therapy was given to a child — known as “Baby KJ” — suffering from a rare metabolic disease in 2025. The therapy was designed and delivered in six months, under a single-patient expanded access IND. Abeona Therapeutics was also awarded FDA approval of its cell-based gene therapy Zevaskyn for the rare skin disorder dystrophic epidermolysis bullosa in the same year. These days, gene therapy doesn't sound like a pipeline story anymore. It's an approvals story.

AI and real-world evidence are addressing the issue of data scarcity. For diseases that have 200 cases worldwide, conventional statistical methods are not effective. New evidence packages are being built and regulators are now accepting them, and they are being designed using the tools of AI-driven pharmacometrics, virtual patient modelling, and natural history datasets, amongst other. Both the FDA's RDEP and the guidance from February 2026 recognize that the natural history evidence and evidence generated using artificial intelligence can provide significant evidence of effectiveness.

Decentralized and adaptive trial designs are tackling the recruitment challenge. The reality is your population is located across continents and it's not feasible to move them to one location for a traditional trial. Virtual visits, remote monitoring, home-based sample collection and adaptive protocols are helping to enable global rare disease trials that were unfeasible 10 years ago.

What This Means for Your Strategy

For the innovative pharma & biotech companies: Rare disease is the next frontier for the most valuable pipeline assets. Early indication selection, real-time monitoring of competitor designations and proactive FDA engagement prior to pivotal trials are now the norm — not best practice.

For the generic drug companies: Rare disease isn't only an innovator's game. Market exclusivity for orphan drugs comes to an end. Biosimilar opportunities in biological rare disease therapies are growing. Keeping track of ODD expiry dates and pinpointing molecules that hit patent cliff in rare indications is becoming an important commercial consideration.

For CROs: Sponsors are looking for partners who have site networks with rare disease experience, relevant PI contacts, and the ability to design adaptive trials. The data from active trials by indication, trial site density or the relationships with sponsors is not just operational data, it is a business development asset.

In each instance, it is the organisations that have access to complete, up-to-date, organised clinical trial information that are gaining an edge — not press releases, or conference abstracts.

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