Idylla MSI test combined with immunohistochemistry is a valuable and cost effective strategy to search for microsatellite instable tumors of noncolorectal origin

Samaison, Laura; Uguen, Arnaud

doi:10.1111/pin.13208

Cited by 7 publications

(6 citation statements)

References 25 publications

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“…Furthermore, it has also been reported a near-total agreement between Idylla results and immunohistochemical assessment of MMR proteins in GC [20,22,23]. Samainson and Uguen reported the Idylla assay as a valuable tool for in-house MSI testing, capable of reducing the diagnosis turnaround time [30]. In line with our results, a small percentage of cases displayed discordant results, suggesting that the Idylla assay should be used sparingly as a single test.…”

Section: Discussionsupporting

confidence: 89%

Performance of Immunohistochemical and Molecular Methods in Detecting Microsatellite Instability in Gastric Cancer: A Multicenter Study

Marques¹,

Gullo²,

Mascarenhas-Lemos³

et al. 2023

Pathobiology

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Introduction: Microsatellite instability (MSI) is an important prognostic molecular biomarker for gastric cancer (GC). MSI status may be detected by immunohistochemistry (IHC) for mismatch repair (MMR) proteins and polymerase chain reaction (PCR). Idylla™ MSI assay has not been validated for GC but may prove to be a valid alternative. Methods: In a series of 140 GC cases, MSI status was evaluated by IHC for MLH1, PMS2, MSH2, and MSH6; gold-standard pentaplex PCR panel (PPP) (BAT-25, BAT-26, NR-21, NR-24, and NR-27); and Idylla. Statistical analysis was performed using SPSS 27.0. Results: PPP identified 102 microsatellite stable (MSS) cases and 38 MSI-high cases. Only 3 cases showed discordant results. Compared with PPP, the sensitivity was 100% for IHC and 94.7% for Idylla. Specificity was 99% for IHC and 100% for Idylla. MLH1 IHC alone showed sensitivity and specificity of 97.4% and 98.0%, respectively. IHC identified three indeterminate cases; all were MSS according to PPP and Idylla. Conclusion: IHC for MMR proteins represents an optimal screening tool for MSI status in GC. If resources are limited, isolated MLH1 evaluation may constitute a valuable option for preliminary screening. Idylla may help detect rare MSS cases with MMR-loss and define MSI status in indeterminate cases.

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Section: Discussionsupporting

confidence: 89%

Performance of Immunohistochemical and Molecular Methods in Detecting Microsatellite Instability in Gastric Cancer: A Multicenter Study

Marques¹,

Gullo²,

Mascarenhas-Lemos³

et al. 2023

Pathobiology

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“…When the manufacturer’s instructions were strictly applied, Idylla MSI Test showed 100% specificity in predicting MSI status, but a slight lower sensitivity when compared with IHC (91.3% vs. 97.3%). Overall, our findings suggest that the use of molecular testing should be used in combination of IHC to provide the maximum yield of concordance 26 and predict with confidence MSI status in EB from GC patients.…”

Section: Discussionmentioning

confidence: 76%

“…24 The fully automated Idylla MSI test (Biocartis) performs the detection of mutations in 7 novel MSI loci and has shown very good performance in colorectal cancer. [25][26][27] However, information regarding the diagnostic performance of Idylla MSI test in GC and, particularly, the accuracy of the assay in biopsy samples is scarce in the literature. [28][29][30] In GC patients with advanced, unresectable, or metastatic disease, the only material available for biomarker assessment are limited biopsy samples in most cases, which might not be representative of the whole tumor.…”

mentioning

confidence: 99%

“…The gold standard for evaluating MSI status in GC is mPCR for 5 mononucleotide markers (pentaplex PCR), according to the Bethesda Guidelines 24 . The fully automated Idylla MSI test (Biocartis) performs the detection of mutations in 7 novel MSI loci and has shown very good performance in colorectal cancer 25–27 . However, information regarding the diagnostic performance of Idylla MSI test in GC and, particularly, the accuracy of the assay in biopsy samples is scarce in the literature 28–30 …”

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confidence: 99%

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Role of Endoscopic Biopsies and Morphologic Features in Predicting Microsatellite Instability Status in Gastric Cancer

Silva

Mascarenhas-Lemos

Nascimento

et al. 2023

American Journal of Surgical Pathology

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Evaluation of mismatch repair (MMR) protein and microsatellite instability (MSI) status plays a pivotal role in the management of gastric cancer (GC) patients. In this study, we aimed to evaluate the accuracy of gastric endoscopic biopsies (EBs) in predicting MMR/MSI status and to uncover histopathologic features associated with MSI. A multicentric series of 140 GCs was collected retrospectively, in which EB and matched surgical specimens (SSs) were available. Laurén and WHO classifications were applied and detailed morphologic characterization was performed. EB/SS were analyzed by immunohistochemistry (IHC) for MMR status and by multiplex polymerase chain reaction (mPCR) for MSI status. IHC allowed accurate evaluation of MMR status in EB (sensitivity: 97.3%; specificity: 98.0%) and high concordance rates between EB and SS (Cohen κ=94.5%). By contrast, mPCR (Idylla MSI Test) showed lower sensitivity in evaluating MSI status (91.3% vs. 97.3%), while maintaining maximal specificity (100.0%). These results suggest a role of IHC as a screening method for MMR status in EB and the use of mPCR as a confirmatory test. Although Laurén/WHO classifications were not able to discriminate GC cases with MSI, we identified specific histopathologic features that are significantly associated with MMR/MSI status in GC, despite the morphologic heterogeneity of GC cases harboring this molecular phenotype. In SS, these features included the presence of mucinous and/or solid components (P=0.034 and <0.001) and the presence of neutrophil-rich stroma, distant from tumor ulceration/perforation (P<0.001). In EB, both solid areas and extracellular mucin lakes were also discriminating features for the identification of MSI-high cases (P=0.002 and 0.045).

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“…Immunohistochemical testing for dMMR has recently become part of the standard repertoire of any pathology laboratory, not least because of the availability of the method. This has also become increasingly true for MSI testing by polymerase chain reaction (PCR) due to simplified technology platforms [ 24 , 30 ]. Several recent guidelines recommend both MMR-immunohistochemistry (IHC) and MSI-PCR as the preferred test with the European Society for Medical Oncology guidelines suggesting to use IHC first [ 16 , 34 ].…”

mentioning

confidence: 99%

Testing for deficient mismatch repair and microsatellite instability

Rüschoff,

Schildhaus,

Rüschoff

et al. 2023

Pathologie

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Testing to detect mismatch repair deficiency (dMMR) and high-grade microsatellite instability (MSI-H) has become an integral part of the routine diagnostic workup for colorectal cancer (CRC). While MSI was initially considered to be a possible indicator of a hereditary disposition to cancer (Lynch syndrome, LS), today the prediction of the therapy response to immune checkpoint inhibitors (ICI) is in the foreground. Corresponding recommendations and testing algorithms are available for use in primary diagnosis (reviewed in: Rüschoff et al. 2021).Given the increasing importance for routine use and the expanding indication spectrum of ICI therapies for non-CRCs, such as endometrial, small intestinal, gastric, and biliary tract cancers, an updated review of dMMR/MSI testing is presented. The focus is on the challenges in the assessment of immunohistochemical stains and the value of PCR-based procedures, considering the expanded ICI indication spectrum. A practice-oriented flowchart for everyday diagnostic decision-making is provided that considers new data on the frequency and type of discordances between MMR-IHC and MSI-PCR findings, and the possible role of Next Generation Sequencing in clarifying them. Reference is made to the significance of systematic quality assurance measures (e.g., QuIP MSI portal and multicenter proficiency testing), including regular continued training and education.

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Idylla MSI test combined with immunohistochemistry is a valuable and cost effective strategy to search for microsatellite instable tumors of noncolorectal origin

Cited by 7 publications

References 25 publications

Performance of Immunohistochemical and Molecular Methods in Detecting Microsatellite Instability in Gastric Cancer: A Multicenter Study

Performance of Immunohistochemical and Molecular Methods in Detecting Microsatellite Instability in Gastric Cancer: A Multicenter Study

Role of Endoscopic Biopsies and Morphologic Features in Predicting Microsatellite Instability Status in Gastric Cancer

Testing for deficient mismatch repair and microsatellite instability

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