Last month, in a joint effort, FDA’s CDER and CBER released the Rare Disease Evidence Principles (RDEP), adding it to existing programs aimed at accelerating patient access, such as Fast Track, Accelerated Approval, Priority Review, and Breakthrough Therapy. The RDEP is independent of and not mutually exclusive with Orphan Drug Designation.

This initiative reflects the FDA’s continued commitment to addressing unmet medical needs and improving patient access to innovative therapies.

In this article, I break down the key aspects of this new guideline.
If you’d like to explore how RDEP could support your program or help accelerate your product’s path to market, please feel free to contact me.

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​What is the RDEP?

The RDEP provides a new framework for accelerating the approval of drugs intended to treat rare, genetically related diseases, where traditional clinical evidence generation is often challenging.

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What is the benefit of the RDEP?

Standard drug approvals typically rely on efficacy and safety data from multiple, large, and independent trials, each designed to substantiate the findings of the other. However, for diseases affecting a very limited number of patients, meeting these requirements is often not feasible.

The RDEP recognizes the acceptability of data from a single well-designed pivotal trial, supported by confirmatory evidence of efficacy and safety to support regulatory decision-making. Such confirmatory evidence may include, for example, non-clinical data, case reports, or natural history studies.

These principles promote scientifically sound and flexible development pathways while maintaining the FDA’s standards for safety and effectiveness.

In summary, the RDEP embraces a totality-of-evidence approach, recognizing multiple sources of data to support regulatory decisions.

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Who is eligible for the RDEP?

Drugs considered for RDEP review are intended to correct a genetic defect (not limited to gene replacement but also addressing the corresponding protein) and must:

• Target a very small population or subpopulation (e.g. less than 1,000 individuals in the U.S.);

• Treat a known in-born genetic defect responsible for the pathology;

• Address a disease that causes rapid functional decline leading to severe disability or death.

• Have no available treatment that modifies the course of the disease.

 

Even for products outside the scope of RDEP, regulatory approval may still be possible based on a single pivotal trial supplemented by confirmatory evidence, provided there is strong scientific rationale and robust results. In such cases, sponsors can initiate dialogue with the FDA through the standard meeting process appropriate to the stage of product development to discuss the acceptability of this approach.

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How to Apply for Review under the RDEP?

Sponsors interested in the RDEP should submit a request to the FDA before initiating the pivotal trial, accompanied by a formal meeting request appropriate to the stage of development. This is typically done via an existing Investigational New Drug (IND) application. If no IND exists, the FDA can assign a pre-IND number to enable early engagement and schedule the meeting.

The request should include reasonable evidence that the drug meets RDEP eligibility criteria and that safety and efficacy can be demonstrated by a single pivotal trial, supported by confirmatory evidence.

Once the FDA accepts the request, an initial meeting is held between the sponsor and the relevant Agency team to align on the confirmatory data needed to support the drug’s safety and efficacy.

 

CONCLUSION

The RDEP confirms the FDA’s long-standing commitment to regulatory flexibility in rare disease development. It sends a clear message: not just clinical data matters, and a holistic, multidisciplinary evidence package can accelerate access to innovative therapies for patients who need them most.