{"entity":{"id":"folr1-expression","kind":"biomarker","name":"Folate receptor alpha expression (FRα-positive, PS2+ >= 75%)","aka":["FRα","FRa","folate receptor alpha positive","FOLR1 expression","FRα-positive","PS2+ >= 75%","FOLR1 IHC"],"tldr":"Folate receptor alpha is a surface protein on most high-grade serous ovarian cancers. Mirvetuximab soravtansine requires FRα-positive disease, scored as at least 75 percent of cells with moderate or strong staining on the Ventana FOLR1 assay.","summary":"Mirvetuximab soravtansine (Elahere) is labelled for FRα-positive platinum-resistant epithelial ovarian, fallopian tube or primary peritoneal cancer after one to three prior regimens, selected with an FDA-approved test; the VENTANA FOLR1 (FOLR-2.1) RxDx Assay scores positive at 75 percent or more of viable tumour cells with moderate (2+) or strong (3+) membrane staining (PS2+ >= 75 percent), the SORAYA and MIRASOL definition. About 35 to 40 percent of high-grade serous cancers are FRα-high by this rule.","asOf":"2026-09-23","links":[{"label":"ELAHERE prescribing information (DailyMed)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=00c424b5-6ccd-48ab-9e88-1986451120e2"}],"tags":["biomarker","surface-antigen"],"related":["brca-somatic","hrd-positive"],"cancers":["ovarian","platinum-resistant-ovarian-cancer","high-grade-serous-ovarian-cancer","endometrial"],"sections":[],"technologies":[],"targets":[],"drugs":["mirvetuximab-soravtansine"],"companies":[],"institutions":[],"pathways":[],"terms":["ihc","platinum-sensitivity"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"target":"folr1","measurement":"ihc-score","scoringRule":{"text":"75 percent or more of viable tumour cells with moderate (2+) or strong (3+) membrane staining intensity (PS2+ >= 75 percent) on the VENTANA FOLR1 (FOLR-2.1) RxDx Assay.","quote":"Select patients for the treatment of platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer with ELAHERE based on the presence of FRα tumor expression","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=00c424b5-6ccd-48ab-9e88-1986451120e2","sourceLabel":"ELAHERE prescribing information"},"thresholds":[{"value":"FRα-positive (PS2+ >= 75% on the Ventana FOLR1 assay)","drugId":"mirvetuximab-soravtansine","cancerId":"platinum-resistant-ovarian-cancer","regulator":"FDA","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=00c424b5-6ccd-48ab-9e88-1986451120e2","quote":"ELAHERE ® is indicated for the treatment of adult patients with folate receptor-alpha (FRα) positive, platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer, who have received one to three prior systemic treatment regimens.","status":"current"}],"tests":[],"assays":["folr1-ventana"],"companionDiagnostics":[{"device":"Ventana FOLR1 (FOLR-2.1) RxDx Assay","maker":"Ventana Medical Systems (Roche)","drugs":["mirvetuximab-soravtansine"],"indication":"Epithelial Ovarian Cancer, Fallopian Tube Cancer, or Primary Peritoneal Cancer - Tissue","pma":"P220006 (11/14/2022)","source":"https://www.fda.gov/medical-devices/in-vitro-diagnostics/list-cleared-or-approved-companion-diagnostic-devices-in-vitro-and-imaging-tools"}],"forPatient":"If your ovarian cancer is platinum-resistant and at least three quarters of the cells stain moderately or strongly for folate receptor alpha, mirvetuximab soravtansine is on label. Eye examinations before and during treatment are required because the drug can blur vision. Lower expression does not qualify under the current label."},"route":"/biomarkers/folr1-expression/","neighbours":{"biomarker":[{"id":"hrd-positive","kind":"biomarker","name":"HRD-positive (genomic instability score)","route":"/biomarkers/hrd-positive/"},{"id":"tissue-factor-expression","kind":"biomarker","name":"Tissue factor expression","route":"/biomarkers/tissue-factor-expression/"},{"id":"brca-somatic","kind":"biomarker","name":"Tumour (somatic or germline) BRCA1/2 mutation and HRR gene alterations","route":"/biomarkers/brca-somatic/"}],"cancer":[{"id":"endometrial","kind":"cancer","name":"Endometrial cancer","route":"/cancers/endometrial/"},{"id":"high-grade-serous-ovarian-cancer","kind":"cancer","name":"High-grade serous ovarian cancer","route":"/cancers/high-grade-serous-ovarian-cancer/"},{"id":"ovarian","kind":"cancer","name":"Ovarian cancer","route":"/cancers/ovarian/"},{"id":"platinum-resistant-ovarian-cancer","kind":"cancer","name":"Platinum-resistant ovarian cancer","route":"/cancers/platinum-resistant-ovarian-cancer/"}],"drug":[{"id":"mirvetuximab-soravtansine","kind":"drug","name":"Mirvetuximab soravtansine","route":"/drugs/mirvetuximab-soravtansine/"}],"term":[{"id":"ihc","kind":"term","name":"Immunohistochemistry (IHC)","route":"/terms/ihc/"},{"id":"platinum-sensitivity","kind":"term","name":"Platinum-sensitive / platinum-resistant","route":"/terms/platinum-sensitivity/"}],"target":[{"id":"folr1","kind":"target","name":"Folate receptor alpha","route":"/targets/folr1/"}]}}