Soluble mesothelin-related peptides (SMRP) - high stability of a potential tumor marker for mesothelioma

Our plain-English summary of Soluble mesothelin-related peptides (SMRP) - high stability of a potential tumor marker for mesothelioma, by D.G. Weber, D. Taeger, B. Pesch, et al (Cancer Biomarkers, 2007).

The study

• Authors: D.G. Weber, D. Taeger, B. Pesch, T. Kraus, T. Brüning, G. Johnen
• Journal: Cancer Biomarkers
• Published: 2007;3(6):287-92
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

SMRP (soluble mesothelin-related peptides) is a promising marker for detection of malignant mesotheliomas (MM) in serum that has not yet been validated in appropriate epidemiological studies. Field studies might not always provide optimal conditions for storage and transport of samples, and follow-up studies have to rely on sample integrity. Proper validation of the marker would require sufficient stability of the antigen and robustness of the assay. SMRP concentrations were evaluated in serum samples of 98 healthy donors, using the MESOMARK ELISA kit. The SMRP distribution in the healthy study population was determined and biological and pre-analytical variations were examined regarding their influence on SMRP concentrations. For diagnostic decisions a best statistical and unbiased cut-off between 1.5 and 1.6 nmol/L was determined (95th percentile). No age- or gender-specific differences could be observed. SMRP exhibits excellent stability regarding short-term storage, long-term storage, and repeated freeze/thaw cycles. Scientific studies as well as real life applications that employ SMRP would not be limited by sample stability issues.

In plain English

This German laboratory study measured soluble mesothelin-related peptides (SMRP), a blood protein proposed as a marker for malignant mesothelioma, in serum from 98 apparently healthy volunteers (47 men, 51 women) with no known history of asbestos exposure, using the MESOMARK test kit. No mesothelioma patients were included. Mean SMRP was 0.8 nmol/L (range 0.1 to 2.1) and was the same in donors over and under 60. No differences by sex were observed. From the 95th percentile of these healthy values, the authors set a cut-off between 1.5 and 1.6 nmol/L. In 30 samples, five days at room temperature did not significantly change SMRP compared with frozen storage. Ten freeze-thaw cycles caused a small, statistically significant rise, though 27 of 30 samples stayed within the test's imprecision. Samples from two donors stored up to 10 years varied within assay imprecision. The authors concluded SMRP showed excellent stability. They said its cancer-predictive value still needs validation in prospective studies of healthy cohorts.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study of serum from healthy volunteers, used to set reference values and a cut-off and to test how sample storage and handling affect results
• Who was studied: 98 apparently healthy Caucasians of European descent (47 men, mean age 47, range 21 to 86; 51 women, mean age 46, range 23 to 92), recruited from employees of the authors' institute (Bochum, Germany) and its associated clinic, with no known history of asbestos exposure; dates of collection not stated
• Exposure: No asbestos exposure was studied. The study tested sample handling: serum SMRP was measured with the commercial MESOMARK ELISA kit after storage for 5 days at minus 80 degrees C, 5 days at room temperature, or 10 freeze/thaw cycles, plus archival samples from two donors stored at minus 20 degrees C for up to 10 years
• Main results:
  • In the 98 healthy donors, SMRP ranged from 0.1 to 2.1 nmol/L, with an arithmetic mean of 0.8 nmol/L (SD 0.4)
  • Mean SMRP was 0.8 nmol/L (SD 0.4) in both donors over 60 (N = 25) and under 60 (N = 73); differences by gender were not observed (data not shown)
  • The 95th percentile cut-off was 1.5 nmol/L (empirical) or 1.6 nmol/L (estimated from a lognormal distribution). The 97.5th percentile was 1.9 nmol/L (empirical) and 1.8 nmol/L (estimated). The 99th percentile was 2.1 nmol/L by both methods
  • A cut-off of 1.5 nmol/L calculated as mean plus 2 SD, which assumes a normal distribution, would classify about 6%, instead of 2.5%, of the healthy subjects as positive
  • In 30 samples, SMRP after 5 days at room temperature did not differ significantly from samples kept at minus 80 degrees C (p = 0.841)
  • In 30 samples, 10 freeze/thaw cycles caused a small, statistically significant rise in SMRP (p = 0.003); 27 of 30 (90%) samples stayed within ELISA imprecision
  • In archival and fresh samples from two donors (stored up to 10 years at minus 20 degrees C), the variation in each donor's SMRP values was within the range of assay imprecision (CV 12.4% and 12.3%)
• The authors' conclusion: The authors concluded that SMRP showed excellent stability during short-term storage, long-term storage and repeated freeze/thaw cycles, so that sample stability would not limit its use. They also advised aliquoting serum before freezing because of the freeze/thaw effect.
• Limitations the authors state:
  • Other biological variations, such as differences between populations or cyclical biological fluctuations, cannot be ruled out and need further study
  • More archival samples from individual donors, stored for different long-term intervals, are needed to confirm the long-term storage findings, which rested on two donors
  • Cut-offs close to the maximum of the data, such as the 97.5th and 99th percentiles, may be more affected by sample size and outliers
  • The marker's cancer-predictive value and clinical applicability still need to be validated in prospective studies of healthy cohorts

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Soluble Mesothelin-Related Peptides (SMRP), Tumor Marker, Mesothelioma, Malignant Mesothelioma.

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• Performance of biomarkers SMRP, CA125, and CYFRA 21-1 as potential tumor markers for malignant mesothelioma and lung cancer in a cohort of workers formerly exposed to asbestos — M. Gube, D. Taeger, et al. (2011)
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