1. Coronavirus/COVID-19 tests
Early in the pandemic, the U.S. only had one FDA-authorized coronavirus test. This test was only available in a handful of cities, and the labs using the test encountered problems during its initial rollout. This led to a testing shortage in the U.S., one that was exacerbated by the fact that all other coronavirus tests in development at the time had to receive emergency use authorization (EUA) from FDA. This meant that CMS-certified labs, which are typically not subject to FDA oversight, had to get prior approval from FDA before introducing LDTs for the coronavirus.
In response to concerns from AACC and the clinical laboratory community, FDA eventually amended its EUA requirements, thereby enabling qualified labs to develop and perform coronavirus LDTs prior to obtaining an EUA. This decision played a critical role in enabling the U.S. to rapidly scale up coronavirus testing to meet the demands of the pandemic. Without these coronavirus LDTs, many people in the U.S. would not have been able to get tested and properly diagnosed with COVID-19.
2. Tests for drugs of abuse
Some hospitals test mothers and newborns for drugs if they suspect the mother of abuse. It is therefore critical that drug tests be as accurate as possible. False positives can have serious consequences—such as mothers losing custody of their children and getting sent to prison.
Currently, LDTs employing a technology known as mass spectrometry are the most reliable tests in existence for drugs of abuse. LDTs eliminate false drug positives in babies, thereby preventing children from being unnecessarily separated from their families.
LDTs also enable labs to identify deadly designer drugs such as fentanyl and its analogs. Because new analogs of fentanyl are constantly emerging, commercial, FDA-approved tests for these drugs cannot keep up with real world changes. It is in situations like these—where testing must evolve rapidly—that LDTs are critical.
3. Blood lead level tests
Lead poisoning causes irreversible neurological damage in children and is a widespread problem throughout the U.S. A survey of 17 cities in Pennsylvania found that 10%-23% of all children had lead poisoning—and the true percentage is likely much higher, as most children in the state have not been tested for it.
The effects of lead poisoning get worse the longer a child is exposed. Blood lead testing is therefore crucial to catching lead poisoning early, so that the source of lead in a child’s environment can be eliminated promptly. Unfortunately, the only FDA-approved analyzers for blood lead testing have been subject to multiple recalls. Making matters worse, there is no financial incentive for IVD companies to develop new blood lead tests as lead poisoning disproportionately impacts underrepresented communities.
Thankfully, labs have been able to create their own LDTs for blood lead levels that meet CDC’s guidelines for lead testing. This has made it possible for children to access high quality lead testing even in the absence of a reliable, FDA-approved test.
4. BRCA and other genetic tests
About 3% of breast cancers and 10% of ovarian cancers result from inherited mutations in the BRCA1 and BRCA2 genes. Women who carry these mutations can significantly reduce their risk of cancer by undergoing either a prophylactic mastectomy or oophorectomy. However, the FDA-approved tests for BRCA1 and BRCA2 are direct-to-consumer tests that only detect a handful of mutations in these genes, even though there are many more cancer-causing BRCA mutations than that. This means that a woman might test negative on an FDA-approved BRCA test and think that she doesn’t have an elevated risk for cancer, when in reality she has a BRCA mutation that the test simply missed.
LDTs, on the other hand, detect the full range of known BRCA mutations, and can identify high risk patients for breast or ovarian cancer whom the commercial tests let slip through the cracks.
In general, genetic testing is similar to testing for drugs of abuse in that our knowledge of clinically significant mutations is evolving so rapidly that FDA’s regulatory process can’t keep up with it—but LDTs can.