Last Updated: October 20, 2026, 11 am UTC
FDA’s Accelerated Approval Program creates an opportunity to bring promising treatments for serious conditions to patients sooner. Yet the pathway introduces a consequential planning challenge: the evidence that supports initial approval and the evidence required to verify clinical benefit must be developed on overlapping timelines.
For rare disease sponsors, those timelines can be particularly unforgiving. Small, geographically dispersed populations, specialized sites, long-term follow-up, and the prospect of commercial availability can each influence whether a confirmatory trial delivers an interpretable answer. The strength of an accelerated approval strategy therefore depends as much on the feasibility of the entire evidence program as on the promise of its early clinical results.
How FDORA Changed Accelerated Approval Planning
The Food and Drug Omnibus Reform Act of 2022 (FDORA) sharpened FDA oversight of confirmatory trials. The Agency can require studies to be underway before accelerated approval or within a specified period afterward, establish progress conditions and milestones, and use expedited withdrawal procedures when requirements are not met. Sponsors must also report progress approximately every 180 days.¹
These changes have material implications for development planning. Confirmatory study startup, funding, contracts, and site activation may need to advance while pivotal data are still being collected and an application is in preparation. The resulting program must accommodate concurrent clinical studies, regulatory review, manufacturing preparation, and potentially commercial launch.
This requires governance across the full development continuum. A program-level leadership team should own a shared timeline, review dependencies among workstreams, and make deliberate trade-offs when scientific or operational assumptions change. A decision about an endpoint, for example, can affect site training, assessment vendors, data systems, patient burden, and the study completion forecast.
Design for Approval and Verification Together
Pivotal and confirmatory protocols should be developed as parts of one evidence strategy. The pivotal study must establish a defensible relationship between the proposed surrogate or intermediate clinical endpoint and anticipated clinical benefit. At the same time, sponsors should consider what functional outcomes, durability measures, and long-term follow-up will ultimately be needed to verify that benefit.
In appropriate programs, a single trial may support accelerated approval through a prespecified earlier analysis and continue collecting longer-term evidence for confirmation. This approach can preserve an established participant population and study infrastructure, but it requires suitable design, statistical power, and protection of trial integrity. In other programs, separate pivotal and confirmatory studies will be necessary. Early FDA discussion of the endpoint, population, dose, trial model, and target completion date is essential in either case.¹
The goal is to anticipate the questions the confirmatory study must answer before protocol decisions become difficult to reverse.
Make “Underway” a Demonstrable State
FDA’s January 2025 draft guidance describes a proposed approach to determining whether a confirmatory trial is underway. In general, it anticipates that enrollment will have begun before accelerated approval, with a justified completion date and credible progress toward meeting it. A finalized protocol, site selection, or executed contracts alone do not establish that enrollment has started.²
Sponsors should be prepared to demonstrate active sites, accrual to date, projected enrollment, available resources, and measurable benchmarks discussed with FDA ahead of submission. The draft guidance recognizes limited circumstances in which a different approach may be justified, including particular challenges in ultra-rare diseases. Expectations remain case-specific, making early regulatory alignment critical.
Feasibility Must Begin With Reachable Patients
In rare disease, prevalence is an inadequate enrollment forecast. A credible feasibility assessment follows the population from diagnosis through eligibility, proximity to capable sites, competing trial participation, and willingness to accept the proposed study design. It should draw on direct conversations with investigators, sites, and patient advocacy organizations rather than relying solely on historical site performance or database estimates.
The model must also account for contracting timelines, referral pathways, specialized equipment, laboratory and vendor setup, screen failures, retention, and the time needed to observe clinical outcomes. Each major assumption should have supporting evidence and a mitigation plan if conditions change.
Crucially, the pivotal and confirmatory studies should not be forecast in isolation. In a small population, they may compete for the same eligible participants. One-time therapies, including some gene therapies, can further narrow the pool available for later studies. Shared population modeling helps determine whether a confirmatory strategy is achievable before sponsors commit to it.
Anticipate What Approval Changes for Patients and Sites
Commercial access can alter the conditions under which a confirmatory trial was designed. Before approval, participation may be a primary route to an investigational treatment. After approval, patients and investigators may weigh randomization, control treatment, additional visits, or follow-up against commercially available care.
Enrollment forecasts should therefore distinguish pre-approval and post-approval conditions by country and site. Retention planning is equally important: a trial needs sufficient participants and endpoint observations to verify benefit, even when patients have new treatment options.
For pediatric and rare disease studies, this means examining the full family journey. Travel, school and work disruption, caregiver responsibilities, procedural burden, and long-term follow-up can influence participation over many years. Sponsors should establish support services, communicate clearly about what approval means for current participants, and anticipate requests to switch treatment or leave the study. Prespecified retention triggers and escalation plans can help preserve both patient experience and data interpretability.
Keep Quality, Manufacturing, and Launch on the Same Clock
The accelerated pathway can compress the interval between data maturity, submission, and potential inspection. Trial master files, audit trails, vendor oversight, and site documentation should remain inspection-ready throughout execution, supported by timely issue resolution and mock inspections before submission.
Chemistry, manufacturing, and controls (CMC) present a parallel constraint. Process comparability, assay validation, stability, facility readiness, and release testing may require lead times that clinical acceleration cannot shorten. Supply planning must account for both continuing trials and commercial demand, particularly for complex biologics and cell and gene therapies.
Commercial planning also needs to protect the confirmatory study. Launch sequencing, treatment center capacity, patient-support models, and product allocation can all affect enrollment and continuity. Decisions made to expand patient access should be evaluated alongside their implications for completing the evidence obligation.
A Plan Built to Reach the Real Finish Line
Accelerated Approval can move a treatment toward patients earlier, but the pathway remains dependent on timely verification of clinical benefit. For sponsors, the practical advantage comes from integrating clinical strategy, regulatory alignment, patient feasibility, operations, quality, CMC, and launch decisions before timing becomes a constraint.
The most durable programs are designed to sustain evidence generation after approval, with a credible path from an early promising signal to verified patient benefit.
Explore Premier Research’s rare disease and regulatory expertise, or speak with our team about building an integrated accelerated approval strategy.
REFERENCES
- U.S. Food and Drug Administration. Expedited Program for Serious Conditions—Accelerated Approval of Drugs and Biologics. Draft Guidance for Industry. December 2024. https://www.fda.gov/media/184120/download
- U.S. Food and Drug Administration. Accelerated Approval and Considerations for Determining Whether a Confirmatory Trial Is Underway. Draft Guidance for Industry. January 2025. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/accelerated-approval-and-considerations-determining-whether-confirmatory-trial-underway
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