Trending Clinical Topic: New Blood Tests

Ryan Syrek

Disclosures

January 21, 2022

Each week, we identify one top search term, speculate about what caused its popularity, and provide an infographic on a related condition. If you have thoughts about what's trending and why, share them with us on Twitter or Facebook.

Earlier this month, a federal jury convicted Elizabeth Holmes, founder of the blood testing startup Theranos, on four of 11 charges of fraud. Her claims about revolutionizing such tests resulted in the company's valuation at $9 billion. When those claims were revealed to be misleading, many questioned whether the public would grow suspicious of legitimate advances in blood tests. Recent studies have confirmed progress in the use of blood to test for various key conditions (see Infographic below), leading to this week's top trending clinical topic.

Research from the UK suggests that pregnant women at risk for preeclampsia can now be identified early, before symptoms develop. The study analyzed genetic material from over 2500 blood samples of pregnant women from eight independent cohorts with multiple demographics, including socioeconomic background, geographic location, ethnicity, and nationality, collected 14.5 weeks before delivery. Researchers used plasma cell–free RNA transcripts to examine the molecular mechanisms in fetal, maternal, and placental tissues. A signal from a single blood sample had a 32.3% positive predictive value and 75% sensitivity. In addition, 73% of participants with a positive predictive value were identified "as destined to have a medically indicated preterm birth over 3 months in advance of the preeclampsia symptoms," said the authors. With as many as 1 in 12 pregnancies affected by preeclampsia and given that the diagnosis is most often only made in the third trimester, these results provide a promising outlook for pregnant women.

Elsewhere, recent data show that a blood-based cancer test can accurately identify cancer in undiagnosed patients with vague symptoms, even differentiating between localized and metastatic disease. A study investigated the use of nuclear magnetic resonance (NMR) metabolomics to analyze blood samples from 300 patients with nonspecific but concerning symptoms of cancer. Unlike conventional blood-based tests for cancer, which look for genetic material from tumors, the NMR-based technique uses magnetic field and radio waves to analyze levels of metabolites in the blood. NMR-based metabolomic analysis correctly detected the presence of solid tumors in 19 out of 20 patients with cancer in the study. It also identified metastatic disease in these patients with an accuracy of 94%. The authors emphasize that the techniques will need testing in a larger cohort of patients to confirm the results and evaluate the utility of the test in a wider clinical context.

In other cancer detection news, a new blood-based biomarker panel combined with a model assessing risk factors for lung cancer better predicts who could benefit most from screening, according to new findings. Hanash and colleagues found that a four-marker protein panel (4MP) — consisting of the precursor form of surfactant protein B (pro-SFTPB), cancer antigen 125, carcinoembryonic antigen, and cytokeratin-19 fragment — can potentially identify individuals at risk for lung cancer. The study found that combining the blood-based 4MP with a lung cancer risk prediction model (PLCOm2012) better identified individuals who would benefit from lung cancer screening compared with the US Preventive Services Task Force (USPSTF) criteria.

Among individuals who had at least a 10–pack-year smoking history, the combination model demonstrated a sensitivity of 88.4%, compared with 78.5% for the USPSTF criteria. Specificity was also better (56.2% vs 49.3%). The 4MP alone yielded an area under the receiver operating characteristic curve (AUC) of 0.79 for specimens drawn from lung cancer cases obtained within 1 year before diagnosis and 0.74 for the entire specimen set. The combined 4MP and PLCOm2012 model yielded an AUC of 0.85 for lung cancer specimens that had been collected within 1 year before diagnosis. The authors note that although the blood test could be implemented as a lab test in the near future, approval from the US Food and Drug Administration would most likely require evaluation through a prospective clinical trial.

In terms of other conditions, a new blood test that identifies a variant of the protein P53 appears to predict Alzheimer's disease (AD) progression up to 6 years in advance of a clinical diagnosis. Analysis of two studies showed that AlzoSure Predict, which uses less than 1 mL of blood, had numerous benefits compared with other blood tests that track AD pathology. Results showed the test predicted decline from mild cognitive impairment to AD at the end of 6 years, with an AUC greater than 90%. The findings were presented at the 14th Clinical Trials on Alzheimer's Disease (CTAD) conference.

Although Holmes's claims were not supported by rigorous science, legitimate advances in blood testing are promising. Detecting preeclampsia and cancer and assessing AD progression all may soon be more accurate and easier, which is why "new blood tests" became this week's top trending clinical topic.

Learn more about lung cancer.

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