According to investigators, laboratory-developed tests (LDTs) as well as U.S. Food and Drug Administration-approved companion diagnostics (FDA-CDs) show a high degree of accuracy and comparable performance for three oncology analytes. The study was published in the journal JAMA Oncology.

The recent debate on LDTs and FDA-CDs has centred upon both the regulatory and performance aspects of LDTs and the team had the data through the proficiency testing (PT) programs to address the latter point, performance, which they want to share with the community.

A total of 6,897 PT responses from laboratories participating in the College of American Pathologists' PT program were included in the analysis: 2,524 BRAF analytes in 14 PT samples; 2,216 EGFR analytes in 11 PT samples; and 2,157 analytes in 10 PT samples.

LDTs and FDA-CDs were compared for both accuracy and laboratories’ preanalytical practices. The researchers found that both LDTs and FDA-CDs demonstrated excellent performance, with both test types exceeding 97% accuracy overall. More than 60% of participants using an FDA-CD modified their assays from the approved procedure.

The modifications reduce the tests LDTs. They appear to be driven by the needs of the real day-to-day clinical practice, which require adapting the assays to meet the needs of a variety of clinical situations that may not be accommodated by the FDA-approved protocol.

It is important to recognize that the study only addresses the accuracy of results from laboratories but not the other aspects of laboratory practice. However, where possible, these other aspects should be published as solid and vetted data through peer-reviewed venues to better inform the community.

At present, there are no convincing arguments that LDTs are inferior to any other type of developed tests including companion diagnostics. That is because as these tests are developed in CLIA-compliant labs, the stakeholders have gone through extensive training with expertise in the design, development, and clinical validation for optimal use.

In addition, there are other oversight bodies such as CAP, licensure or board certification of practitioners, to make sure these tests are effective and patient-centered, backed by the highest level of quality control and assurance on the methods and procedures.

Separately, a research letter in the same issue of the journal reports on a comparison of two platforms for targeted next-generation sequencing of cell-free (cf)DNA: Guardant360 (GuardantHealth, Inc) and PlasmaSELECT (Personal Genome Diagnostics, Inc).

Investigators found very low similarity for paired samples from 40 volunteers with metastatic prostate cancer, raising the possibility that patients could receive different treatments depending on the cfDNA platform.

The FDA has a good track record of determining if a new drug or new indication is safe and effective. However, analysis for tumour biomarker tests is much less consistent. A more consistent regulatory environment for tumour biomarker tests needed so that clinicians and patients could be confident that a test used to direct care is as good as the drug, the researchers conclude.