Last Updated: March 10, 2026, 10 am UTC

In February 2026, the Food and Drug Administration (FDA) outlined a meaningful evolution in the Agency’s evidentiary approach to drug approval: establishing one adequate and well-controlled trial, supported by confirmatory evidence, as the default basis for marketing authorization. This position was articulated in The New England Journal of Medicine in “One Pivotal Trial, the New Default Option for FDA Approval — Ending the Two-Trial Dogma” (February 19, 2026).ⁱ

The authority to approve a product on the basis of a single adequate and well-controlled investigation is not a new concept. The Food and Drug Administration Modernization Act of 1997 (FDAMA) amended the statutory definition of “substantial evidence” to permit approval based on one such study together with confirmatory evidence, where the FDA determines that the totality of the data is sufficient (21 U.S.C. § 355(d), as amended by FDAMA). Those familiar with the 505(b)(2) regulatory pathway are accustomed to the use of data from multiple sources to serve as confirmatory data for approval. Today, sponsors are increasingly exploring additional evidentiary approaches—including real-world data and external control arms—to strengthen confirmatory evidence in single pivotal study submissions.

In addition, the FDA’s 2023 Draft Guidance for Industry, Demonstrating Substantial Evidence of Effectiveness With One Adequate and Well-Controlled Clinical Investigation and Confirmatory Evidence, provides practical considerations for sponsors pursuing this pathway.ⁱⁱ

What has changed is the Agency’s explicit articulation that this approach will serve as the FDA’s new default standard. Sponsors may now structure development programs with a single pivotal trial in mind—provided that the broader scientific record substantiates the approval decision.

Credibility Under a Concentrated Evidentiary Model

The historical reliance on two pivotal trials reduced statistical uncertainty in an era of more limited biologic precision. Modern regulatory review, however, evaluates a broader constellation of factors, including mechanistic plausibility, effect magnitude, control arm integrity, endpoint validity, and statistical methodology.

Under a one-trial framework, evidentiary weight concentrates rather than distributes. The approval decision rests heavily on three pillars:

Design discipline. Endpoint selection, comparator appropriateness, powering assumptions, and statistical architecture must withstand concentrated scrutiny.

Scientific coherence. Mechanistic/biological data, translational findings, and clinical outcomes must align in a consistent, persuasive narrative.

Operational integrity. Data quality, protocol adherence, and documentation standards assume heightened importance when a single study anchors the filing.

The evidentiary threshold has not shifted. The margin for corrective flexibility has narrowed.

Confirmatory Evidence as Integrated Strategy

The standard requires one adequate and well-controlled investigation supported by confirmatory evidence. That evidence may include mechanistic data, related-indication experience, real-world evidence, or other scientifically relevant sources. In certain contexts, particularly in rare disease and oncology development, sponsors may also leverage innovative evidentiary approaches such as external control arms derived from natural history datasets or real-world data to strengthen confirmatory evidence. The FDA’s guidance on the use of externally controlled trials provides additional considerations for sponsors evaluating these approaches.ⁱⁱⁱ The Agency has also referenced the role of Bayesian statistical methods and other modern analytical approaches in evaluating the credibility of integrated data and conclusions that can be drawn from them.

For sponsors, this elevates earlier development work from transitional activity to strategic asset.

Nonclinical and early-phase clinical programs should be intentionally constructed to reinforce:

Biological plausibility
Quantitative consistency across datasets
Endpoint selection rationale
Clinical interpretability

In effect, the approval argument becomes cumulative rather than duplicative. Replication can be replaced by integration, but this increases the weight of – and risk associated with – each datapoint.

Safety Exposure and Risk Characterization

Two pivotal trials historically expanded patient exposure, strengthening safety databases. A one-trial default does not diminish this requirement.

The FDA retains authority to require additional studies where mechanisms are uncertain, surrogate endpoints are unstable, or methodological limitations affect interpretability. Sponsors pursuing a single-study strategy should therefore consider safety architecture early, including:

Adequacy of total patient exposure
Duration of follow-up
Postmarketing surveillance planning

The number of pivotal trials may change. The obligation to characterize risk comprehensively does not.

Regulatory Engagement Becomes Crucial

A one-trial pathway leaves limited room for misalignment. Early and deliberate FDA engagement is therefore foundational.

Alignment on endpoints, estimands, statistical plans, safety expectations, and the role of confirmatory evidence should occur before execution is underway. Mechanisms such as Special Protocol Assessment (SPA) may warrant renewed consideration when a single study is intended to carry the approval decision.

At the same time, sponsors must navigate operational realities. Recent sponsor experience reflects ongoing constraints on FDA capacity, contributing to delayed responses and increased reliance on written exchanges rather than live meetings.

This shift materially alters the engagement strategy.

In face-to-face meetings, sponsors can clarify misunderstandings in real time, adapt the discussion based on Agency reaction, and contextualize data dynamically. In a written-response environment, that flexibility disappears, as the briefing package effectively becomes the meeting.

Accordingly, written submissions should:

Provide full context, not just discrete answers.
Articulate the scientific narrative explicitly.
Humanize the clinical context where appropriate. In the absence of live discussion, a concise patient story or articulation of disease impact and unmet need can frame urgency and relevance.
Anticipate interpretive risk.
Integrate analysis with explanation.
Plan for delay.

When regulatory engagement increasingly occurs through structured written exchanges, clarity and narrative coherence become decisive. In a one-trial framework, that written record may shape the outcome of the entire program.

Therapeutic Context and Strategic Positioning

Regulatory flexibility has historically been exercised more frequently in areas such as oncology and rare disease, where effect size and mechanistic clarity may support approval based on a single investigation.

In broader or more heterogeneous indications, evidentiary expectations may remain rigorous. The new default establishes a regulatory posture—not an entitlement. Sponsors must demonstrate that one adequate and well-controlled trial, supported by confirmatory evidence, satisfies the statutory standard of substantial evidence.

Strategic positioning—articulating unmet need, contextualizing effect magnitude, and aligning mechanism with clinical relevance—will influence that determination.

Economic and Strategic Implications

The February 2026 New England Journal of Medicine article notes that a single pivotal trial may cost between $30 million and $150 million and contribute to development timelines that often exceed seven years.

Avoiding a second large-scale study has the potential to reduce capital requirements and accelerate time to market. However, efficiencies are program-dependent. A one-trial strategy may require:

More intensive upfront statistical planning
Stronger translational integration
Elevated operational discipline
Early investment in confirmatory evidence generation
Earlier alignment between regulatory, clinical, and CMC teams to ensure manufacturing readiness for accelerated clinical development timelines

The primary advantage may be time compression, where scientific foundations justify it. For sponsors, that compression can shift pressure upstream, requiring earlier preparation for registrational manufacturing, scale-up, and commercial readiness.

A Recalibrated Standard

The FDA has made clear that conducting multiple trials does not, in itself, ensure reliable conclusions. Replication alone cannot substitute for rigorous design.

By establishing one adequate and well-controlled investigation plus confirmatory evidence as the default standard, the Agency signals confidence in the maturity of modern drug development—mechanistic insight, advanced analytics, and integrated evidence assessment.

For sponsors, the opportunity is significant, as is the responsibility. Programs built on disciplined design, cohesive science, early regulatory alignment, and realistic operational planning are positioned to benefit. Those reliant on redundancy to offset uncertainty may find the new environment less forgiving.

The shift is not about conducting fewer studies; it is about constructing stronger ones—and ensuring the written record supporting them reflects that strength.

If your development strategy is evolving in light of the FDA’s one-trial framework, our regulatory and clinical teams can help assess whether this pathway is appropriate for your program—and how to design it for success. Contact us to continue the conversation.

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Premier is built with the needs of biotech in mind, turning breakthrough science into life-changing drugs, devices, and diagnostics by addressing trial complexity, overcoming development hurdles, and demonstrating product value.

Leveraging deep therapeutic expertise, innovative technology, and product development operational proficiency—from preclinical planning to clinical trial execution and commercialization—our integrated approach offers personalized, end-to-end solutions to identify the pertinent data and insight necessary to make informed decisions earlier and deliver accelerated development timelines for a smarter, faster path to approval. To learn more, visit premier-research.com.

REFERENCES:

[i] Prasad V, Makary MA. One Pivotal Trial, the New Default Option for FDA Approval — Ending the Two-Trial Dogma. N Engl J Med. 2026;394:815–817.

[ii] U.S. Food and Drug Administration. Demonstrating Substantial Evidence of Effectiveness With One Adequate and Well-Controlled Clinical Investigation and Confirmatory Evidence: Draft Guidance for Industry. September 2023. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/demonstrating-substantial-evidence-effectiveness-one-adequate-and-well-controlled-clinical

[iii] U.S. Food and Drug Administration. Considerations for the Design and Conduct of Externally Controlled Trials for Drug and Biological Products. Draft Guidance for Industry. February 2023.
https://www.fda.gov/regulatory-information/search-fda-guidance-documents/considerations-design-and-conduct-externally-controlled-trials-drug-and-biological-products