Possibility for FDA to adopt indirect methods for governing Laboratory Developed Tests (LDTs)

Possibility for FDA to adopt indirect methods for governing Laboratory Developed Tests (LDTs)

Following the May 2025 decision by the U.S. District Court for the Eastern District of Texas that vacated the FDA's 2024 final rule on LDTs, the agency has returned to its historical approach of enforcement discretion rather than formal regulation.

The court found that the FDA lacked statutory authority to regulate LDTs as medical devices under the Federal Food, Drug, and Cosmetic Act (FDCA). In response, the FDA chose not to appeal the decision, effectively halting comprehensive FDA oversight for now.

Despite this setback, the FDA has not fully retreated but appears to be recalibrating its regulatory efforts. The agency may pursue renewed action through new guidance, revised rules, or targeted enforcement in the future, leaving the industry advised to maintain vigilance regarding potential shifts.

One such avenue for the FDA to assert authority over LDTs is through the use of warning letters and targeted enforcement actions. Although the final rule was vacated, the FDA has continued to use warning letters and other enforcement tools to address specific cases of safety concerns or noncompliance with applicable regulations.

For instance, the FDA issued a warning letter to DRG Instruments in a case where an assay labeled for research use only was intended for clinical diagnostic use instead. Similarly, the FDA issued a warning letter to Agena Bioscience a year earlier for similar violations.

These warning letters serve as a mechanism to remind or compel laboratories to adhere to standards and address issues with test quality or claims without formal premarket review requirements being broadly applied. This indicates that the FDA is exercising a more reactive and individualized enforcement strategy rather than implementing a comprehensive regulatory framework post-court ruling.

The Association for Molecular Pathology (AMP), an industry group that brought the lawsuit against the FDA over the direction of LDT regulation, favors a tiered, risk-based structure that avoids duplication of activities within federal agencies. AMP proposes updating the Clinical Laboratory Improvement Amendments (CLIA) regulations through Congress rather than increasing FDA authority.

In conclusion, the FDA’s strategy for regulating LDTs after the court decision is essentially a return to the agency’s historical approach of enforcement discretion. The agency is maintaining the ability to exercise authority via warning letters and targeted enforcement actions on a case-by-case basis to address safety or compliance concerns. This cautious, enforcement-driven approach reflects a tactical recalibration rather than a full FDA withdrawal from LDT oversight, with the regulatory landscape remaining dynamic and subject to future policy developments.

[1] https://www.fda.gov/medical-devices/regulatory-information-resources/laboratory-developed-tests-ldts [3] https://www.fda.gov/news-events/press-announcements/fda-announces-court-decision-vacating-final-rule-regarding-laboratory-developed-tests [5] https://www.fda.gov/medical-devices/letters-stakeholders-and-industry/warning-letters-laboratory-developed-tests-ldts-and-in-vitro-diagnostic-devices-ivds

1. The FDA's approach towards LDTs, after the court decision, is a return to its historical enforcement discretion, as opposed to formal regulation.
2. LDT manufacturers should be vigilant, as the FDA may pursue renewed action in the future via new guidance, revised rules, or targeted enforcement.
3. The FDA has shown it can assert authority over LDTs through the use of warning letters and targeted enforcement actions, as seen in cases like DRG Instruments and Agena Bioscience.
4. These warning letters serve as a mechanism to remind or compel laboratories to adhere to standards, addressing issues without broadly applying premarket review requirements.
5. The Association for Molecular Pathology (AMP) prefers a tiered, risk-based structure that updates the Clinical Laboratory Improvement Amendments (CLIA) regulations through Congress, rather than increasing FDA authority.
6. To stay updated on FDA guidelines and enforcement activities regarding LDTs, one can refer to the FDA's websites on medical devices, press announcements, and warning letters.
7. The regulatory landscape for LDTs remains dynamic and is subject to future policy developments, reflecting a cautious, enforcement-driven approach from the FDA.

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