TY - JOUR
T1 - Accuracy of four mononucleotide-repeat markers for the identification of DNA mismatch-repair deficiency in solid tumors
AU - Takehara, Yuko
AU - Nagasaka, Takeshi
AU - Nyuya, Akihiro
AU - Haruma, Tomoko
AU - Haraga, Junko
AU - Mori, Yoshiko
AU - Nakamura, Keiichiro
AU - Fujiwara, Toshiyoshi
AU - Boland, C. Richard
AU - Goel, Ajay
N1 - Funding Information:
This work was supported by grants CA72851, CA181572, CA184792, CA187956 and CA202797 from the National Cancer Institute, National Institutes of Health, a grant (RP140784) from the Cancer Prevention Research Institute of Texas (CPRIT), pilot grants from the Baylor Sammons Cancer Center and Foundation, and funds from the Baylor Research Institute. The present work was also partially supported by MEXT/JSPS KAKENHI (20590572, 25860409, 26462016, and 15H03034).
Publisher Copyright:
© 2018 The Author(s).
PY - 2018/1/12
Y1 - 2018/1/12
N2 - Background: To screen tumors with microsatellite instability (MSI) arising due to DNA mismatch repair deficiency (dMMR), a panel of five quasi-monomorphic mononucleotide-repeat markers amplified in a multiplex PCR (Pentaplex) are commonly used. In spite of its several strengths, the pentaplex assay is not robust at detecting the loss of MSH6-deficiency (dMSH6). In order to overcome this challenge, we designed this study to develop and optimize a panel of four quasi-monomorphic mononucleotide-repeat markers (Tetraplex) for identifying solid tumors with dMMR, especially dMSH6. Methods: To improve the sensitivity for tumors with dMMR, we established a quasi-monomorphic variant range (QMVR) of 3-4bp for the four Tetraplex markers. Thereafter, to confirm the accuracy of this assay, we examined 317 colorectal cancer (CRC) specimens, comprising of 105 dMMR [45 MutL homolog (MLH)1-deficient, 45 MutS protein homolog (MSH)2-deficient, and 15 MSH6-deficient tumors] and 212 MMR-proficient (pMMR) tumors as a test set. In addition, we analyzed a cohort of 138 endometrial cancers (EC) by immunohistochemistry to determine MMR protein expression and validation of our new MSI assay. Results: Using the criteria of ≥1 unstable markers as MSI-positive tumor, our assay resulted in a sensitivity of 97.1% [95% confidence interval (CI)=91.9-99.0%] for dMMR, and a specificity of 95.3% (95% CI=91.5-97.4%) for pMMR CRC specimens. Among the 138 EC specimens, 41 were dMMR according to immunohistochemistry. Herein, our Tetraplex assay detected dMMR tumors with a sensitivity of 92.7% (95% CI=80.6-97.5%) and a specificity of 97.9% (95% CI=92.8-99.4%) for pMMR tumors. With respect to tumors with dMSH6, in the CRC-validation set, Tetraplex detected dMSH6 tumors with a sensitivity of 86.7% (13 of 15 dMSH6 CRCs), which was subsequently validated in the EC test set as well (sensitivity, 75.0%; 6 of 8 dMSH6 ECs). Conclusions: Our newly optimized Tetraplex system will help offer a robust and highly sensitive assay for the identification of dMMR in solid tumors.
AB - Background: To screen tumors with microsatellite instability (MSI) arising due to DNA mismatch repair deficiency (dMMR), a panel of five quasi-monomorphic mononucleotide-repeat markers amplified in a multiplex PCR (Pentaplex) are commonly used. In spite of its several strengths, the pentaplex assay is not robust at detecting the loss of MSH6-deficiency (dMSH6). In order to overcome this challenge, we designed this study to develop and optimize a panel of four quasi-monomorphic mononucleotide-repeat markers (Tetraplex) for identifying solid tumors with dMMR, especially dMSH6. Methods: To improve the sensitivity for tumors with dMMR, we established a quasi-monomorphic variant range (QMVR) of 3-4bp for the four Tetraplex markers. Thereafter, to confirm the accuracy of this assay, we examined 317 colorectal cancer (CRC) specimens, comprising of 105 dMMR [45 MutL homolog (MLH)1-deficient, 45 MutS protein homolog (MSH)2-deficient, and 15 MSH6-deficient tumors] and 212 MMR-proficient (pMMR) tumors as a test set. In addition, we analyzed a cohort of 138 endometrial cancers (EC) by immunohistochemistry to determine MMR protein expression and validation of our new MSI assay. Results: Using the criteria of ≥1 unstable markers as MSI-positive tumor, our assay resulted in a sensitivity of 97.1% [95% confidence interval (CI)=91.9-99.0%] for dMMR, and a specificity of 95.3% (95% CI=91.5-97.4%) for pMMR CRC specimens. Among the 138 EC specimens, 41 were dMMR according to immunohistochemistry. Herein, our Tetraplex assay detected dMMR tumors with a sensitivity of 92.7% (95% CI=80.6-97.5%) and a specificity of 97.9% (95% CI=92.8-99.4%) for pMMR tumors. With respect to tumors with dMSH6, in the CRC-validation set, Tetraplex detected dMSH6 tumors with a sensitivity of 86.7% (13 of 15 dMSH6 CRCs), which was subsequently validated in the EC test set as well (sensitivity, 75.0%; 6 of 8 dMSH6 ECs). Conclusions: Our newly optimized Tetraplex system will help offer a robust and highly sensitive assay for the identification of dMMR in solid tumors.
KW - Colorectal cancer
KW - DNA mismatch repair
KW - Endometrial cancer
KW - Hypermutated tumors
KW - Microsatellite instability
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U2 - 10.1186/s12967-017-1376-4
DO - 10.1186/s12967-017-1376-4
M3 - Article
C2 - 29329588
AN - SCOPUS:85040444679
SN - 1479-5876
VL - 16
JO - Journal of Translational Medicine
JF - Journal of Translational Medicine
IS - 1
M1 - 5
ER -
