Abstract 741P
Background
Determination of the molecular subtype of endometrial cancer has been shown to be prognostic and predictive and is therefore essential for treatment decisions and prognosis prediction in endometrial cancer. Therefore, assessment of mismatch repair protein (MMR) deficiency by immunohistochemistry (IHC) and sequential microsatellite instability (MSI) in cases with indeterminate protein expression status is part of routine diagnostics in the diagnosis of endometrial cancer. Several methods are available for MSI analysis.
Methods
We compared the Idylla™ MSI Assay (Biocartis) with our institutional MSI gold standard test (Bethesda panel) and with MMR IHC in a cohort of n=332 hysterectomy specimen of endometrioid adenocarcinomas of the corpus uteri (2008-2016). MSI tests were performed according to the manufacturer's recommendations (Idylla™) and a validated internal protocol (Bethesda panel). MMR IHC was analyzed using tissue microarrays, but repeated on whole slides in case of a negative internal control or a discrepancy with the MSI test. The Idylla™ MSI results were compared with the Bethesda MSI results and the MMR-IHC.
Results
In our cohort of n=332 endometrioid endometrial cancer cases, MMR IHC, Idylla™ MSI and gold standard (Bethesda) MSI test results were evaluable in all cases, n=325, and n=324, respectively. N=87/332 (26.2%) had MMR deficiency (MMRd) with n=78/332 (23.5%) showing MLH1/PMS2 loss. The Idylla™ MSI assay revealed MSI in n=68/325 (20.9%) cases. Idylla™ results agreed with MMR IHC results in n=303/325 cases (overall percentage agreement (OPA)=93.2%; Kappa= 0.814). Bethesda results were consistent with MMR IHC results in n=310/324 cases (OPA=95.7%; Kappa= 0.884). Both Idylla™ and Bethesda MSI results were available for n=322/332 cases (97.0%) with n=308/322 concordant cases. OPA between the two MSI test methods was therefore 95.65% (Kappa= 0.874).
Conclusions
Idylla™ MSI showed a very high OPA with the gold standard MSI test and with MMR IHC. In view of its short turnaround time and ease of use, this test could therefore be an excellent alternative for MSI testing in endometrial cancer, even with old tissue samples.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Biocartis provided the cartridges free of charge.
Disclosure
R. Erber: Financial Interests, Institutional, Research Funding: Biocartis; Financial Interests, Personal, Invited Speaker: AstraZeneca. I. Unser, A. Hartmann, R. Stöhr: Financial Interests, Institutional, Research Funding: Biocartis. All other authors have declared no conflicts of interest.
Resources from the same session
651P - Phase I study of XNW27011, a novel claudin 18.2 ADC, in patients with locally advanced and/or metastatic solid tumors
Presenter: Jinming Yu
Session: Poster session 01
652P - BT8009 monotherapy in enfortumab vedotin (EV)-naïve patients (pts) with metastatic urothelial carcinoma (mUC): Updated results of Duravelo-1
Presenter: Oscar Reig Torras
Session: Poster session 01
653P - A phase I dose escalation study of EBC-129, a first-in class, anti N-glycosylated CEACAM5 & CEACAM6 antibody-drug conjugate (ADC) in patients with solid tumors
Presenter: Matthew Chau Hsien Ng
Session: Poster session 01
654P - Peripheral neuropathy (PN) following treatment (tx) with bicycle toxin conjugates (BTCs) BT8009 or BT5528 monotherapy in patients (pts) with advanced solid tumors
Presenter: Bernard Doger de Spéville
Session: Poster session 01
655P - Toxicity and efficacy of antibody drug conjugates (ADC) in advanced solid tumors: A pooled analysis of Sarah Cannon UK
Presenter: Rachel Woodford
Session: Poster session 01
656P - Phase I/Ib open-label study of an HER2-targeted T cell engager (TCE)‒SAR443216 in patients (pts) with advanced solid tumors: Intravenous (IV) dose-escalation results
Presenter: Victor Moreno Garcia
Session: Poster session 01
657P - Prospective validation of the T cell engager (TCE) score in patients treated with bispecific CD3 TCE antibodies in phase I clinical trials
Presenter: Noé Herbel
Session: Poster session 01
658P - First-in-human phase I trial of oncolytic herpes simplex virus ONCR-177 alone or in combination with pembrolizumab in advanced solid tumors
Presenter: Cátia Fava Gaspar
Session: Poster session 01
659P - Combination treatment with TTX-030, a first-in-class anti-CD39 antibody, in patients with advanced pancreatic cancer
Presenter: Zev Wainberg
Session: Poster session 01
660P - Atezolizumab plus UCPvax telomerase CD4 TH1-inducer cancer vaccine for the treatment of chemorefractory HPV+ cancers: Safety and efficacy results of the VolATIL phase II study
Presenter: Laura Mansi
Session: Poster session 01