# FDA laboratory-developed test (LDT) rule

Source: https://onco.cc/terms/fda-ldt-rule/  
OnCo record `fda-ldt-rule` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Most cancer tests in the US, including Galleri, Signatera and Oncotype DX, are 'lab-developed tests' overseen through lab standards rather than FDA approval; the FDA's 2024 attempt to change that was struck down in court in 2025.

## Summary

On 6 May 2024 the FDA issued a final rule declaring that in vitro diagnostics are devices even when made by a laboratory, with a four-year phase-in of medical-device requirements for LDTs. On 31 March 2025 the US District Court for the Eastern District of Texas (ACLA and AMP v. FDA) vacated the rule, holding that the agency lacked authority over laboratory services under the device definition, and the FDA did not appeal; on 19 September 2025 it issued a rule restoring the pre-2024 regulatory text. LDTs therefore remain regulated under CLIA (laboratory quality) and, for coverage, by Medicare's MolDX programme and New York State, with FDA review only where a company chooses PMA or De Novo (as GRAIL has with Galleri, and Exact did with Cologuard). For patients, the practical meaning is that an LDT's clinical claims have not been independently reviewed by the FDA, and that a Medicare coverage decision often matters more than approval.

## Fields

- Kind: Term
- Last checked: 2026-09-10

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Laboratory-developed_test
- FDA: Laboratory Developed Tests: https://www.fda.gov/medical-devices/in-vitro-diagnostics/laboratory-developed-tests

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- terms: [Association for Molecular Pathology v. Myriad Genetics (2013)](https://onco.cc/terms/myriad-ruling/), [IVDR (EU In Vitro Diagnostic Regulation 2017/746)](https://onco.cc/terms/ivdr/), [Regulators beyond the FDA (EMA/CHMP, MHRA, PMDA, NMPA, TGA)](https://onco.cc/terms/regulatory-agencies/), [State biomarker testing coverage laws](https://onco.cc/terms/state-biomarker-testing-laws/)
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