FDA’s LDT (Laboratory Developed Tests) Final Rule – Update

More information from the FDA Website.

Along with the final rule, FDA released several related resources, including: 


If you have any questions or need support concerning the FDA’s LDT Final Rule, please contact Angelo Scangas.

Summary of the FDA’s LDT Final Rule

On Monday, April 29, 2024, FDA announced the publication of its Final Rule to regulate laboratory developed testing services (LDTs) as medical devices under the Food, Drug & Cosmetic Act (FDCA), less than five months after the close of the public comment period on the proposed rule. Like the proposed rule, the Final Rule amends the definition of “in vitro diagnostic product” at 21 CFR 809.3 to include “when the manufacturer of these products is a laboratory,” and announces a staged phaseout of enforcement discretion. 

The Final Rule comes in response to over 6,500 comments from stakeholders during the public consultation phase, reflecting widespread interest and concern. Most of the final rule’s preamble addresses these comments, providing the FDA’s justifications for this broad assertion of regulatory power.

The Final Rule includes a phased, five-stage “phase-out” of enforcement discretion over four years, demanding escalating compliance from labs, with certain exemptions for tests addressing “unmet needs” and those approved by specific programs.

The FDA’s move reflects a shift from voluntary compliance to mandatory regulation, highlighting a pivotal change in the landscape for medical diagnostics amidst ongoing debate over the FDA’s authority and the scope of its regulatory powers.

Firms should review their current LDT practices and identify gaps in compliance with the new FDA requirements. This includes understanding the new definitions and preparing for the phased requirements. They should then develop a strategic plan to address the upcoming regulatory changes. This should include preparing for the submission of documentation and aligning LDT operations with FDA standards.

Early implementation of quality systems in compliance with FDA regulations will be crucial, especially given the complexity and time required to develop and validate these systems.

The 5-Stage "Phase-Out" of Enforcement Discretion

Four-year phase-in of medical device regulatory requirements: In the LDT Final Rule, FDA established a slightly modified version of its proposed phase-in schedule for industry to comply with medical device requirements:

Stage 1 (1 year after the effective date of the LDT Final Rule, July 5, 2024): 

Compliance with respect to medical device reports (“MDR”) and correction and removal reporting requirements, and complaint file requirements under the Quality System Regulation (“QSR”). Notably, FDA expects manufacturers to comply with these requirements for the LDTs subject to this phaseout policy before it expects compliance with clearance or approval requirements.

Stage 2 
(2 years after the effective date): Compliance with medical device requirements other than MDR, correction and removal reporting, complaint files, and registration and listing.

Stage 3 
(3 years after effective date): Compliance with respect to QSR requirements other than complaint files.

Stage 4 
(3.5 years after effective date of the final rule): Compliance with respect to premarket review for high-risk LDTs. FDA indicates that it will use the existing device classification rubric for LDTs, with “low,” “medium,” and “high” risk corresponding to Class I, II, and III, respectively. FDA notes that it does not intend to take enforcement against high-risk devices with timely-submitted premarket submissions until the agency completes review of its application. The phase-in period for premarket review notably aligns with the timeframe for renewal of the Medical Device User Fee Amendments (“MDUFA”) in 2027.

Stage 5 
(4 years after effective date of the final rule): Compliance with respect to premarket review for moderate- and low-risk LDTs.

Targeted Enforcement Discretion Policies

FDA has also adopted various enforcement discretion policies based on its assessments of the risks and benefits of certain classes of LDTs. These include a number of new policies in the LDT Final Rule in response to comments.

FDA plans to continue to exempt from all medical device requirements certain categories of tests that it believes are unlikely to pose significant risks, or are conducted in circumstances that will mitigate those risks, such as being subject to other regulatory oversight. These include LDTs of the type on the market at the time of the 1976 Medical Device Amendments to the FDCA; human leukocyte antigen (“HLA”) tests designed, manufactured, and used within a single laboratory appropriately certified under the Clinical Laboratory Improvement Amendments (“CLIA”); and, tests solely for forensic or law enforcement purposes. In the LDT Final Rule, FDA added to this list LDTs manufactured and performed within the U.S. Department of Defense (“DoD”) or the Veterans Health Administration (“VHA”).[6]

In the final rule, FDA also adopted an enforcement discretion policy with respect to premarket review requirements for LDTs approved by the New York State Department of Health’s Clinical Laboratory Evaluation Program (“NYS CLEP”). The agency acknowledged that NYS CLEP’s review of high and moderate risk LDTs for analytical and clinical validity mitigated risks of inaccurate or unreliable LDTs.[7]

Lastly, the FDA stated that it would not enforce premarket requirements and most QSR requirements for certain classes of LDTs, based on the lower risk associated with those tests, a specific unmet need for those devices, or both factors.

These classes include validated LDTs manufactured and performed by a laboratory integrated within a healthcare system to meet an unmet need of patients receiving care within the same healthcare system—a nod to concerns from academic medical centers.

Other classes of LDT subject to this enforcement discretion policy include currently marketed IVDs offered as LDTs prior to the issuance of the LDT Final Rule, provided they are not modified in ways that could affect their basic safety and effectiveness profile, and non-molecular antisera LDTs for rare red blood cell (RBC) antigens manufactured and performed by blood establishments, for which there is no alternative IVD available to meet a patient’s need for a compatible blood transfusion.

Several Open Questions Remain Regarding FDA’s Implementation of the Final Rule.

  1. What is the scope of “IVDs offered as LDTs”? FDA acknowledges that this is broader than its traditional definition of an LDT, and includes tests that are offered as LDTs by CLIA-certified, high-complexity laboratories, even if they are not designed, manufactured, and used within a single laboratory. However, the boundaries of this definition—versus what FDA considers to be a traditional LDT, and therefore subject to certain targeted enforcement discretion policies—are unclear.
  2. FDA intends to leverage its authority under 21 CFR § 807.26(e) to require labeling submissions from laboratories that will offer tests subject to targeted enforcement discretion from premarket review, but is this a proper exercise of FDA’s authority under this provision? It is not clear that this regulation anticipates FDA’s sweeping request for labeling submissions for categories of tests or developers.
  3. How will laboratories comply with labeling requirements for LDTs? The IVD labeling requirements under 21 CFR § 809.10 are incredibly detailed and nuanced, and do not translate well to tests that are not packaged and distributed. The Final Rule states only that FDA intends to provide more targeted guidance and/or additional resources regarding applicable labeling requirements prior to stage 2 of the phaseout period.

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