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Test Code AFOLR Folate Receptor Alpha (FOLR1), Semi-Quantitative Immunohistochemistry, Manual


Ordering Guidance


This test may be utilized for all types of ovarian cancers.



Shipping Instructions


Attach the green "Attention Pathology" address label (T498) to the outside of the transport container before putting into the courier mailer.



Necessary Information


A pathology/diagnostic report and a brief history are required.



Specimen Required


Specimen Type: Tissue

Source: Ovarian tumor

Supplies: Pathology Packaging Kit (T554)

Collection Instructions: Formalin-fixed, paraffin-embedded tissue block; or 3 unstained glass, "positively charged" slides with 4-microns formalin-fixed, paraffin-embedded tissue

Additional Information: One slide will be stained with hematoxylin and eosin and returned.


Secondary ID

620731

Useful For

Diagnosis of epithelial ovarian cancer that may be eligible for treatment with an anti-folate receptor 1 protein antibody

Method Name

Immunohistochemistry (IHC)

Reporting Name

FOLR1, SemiQuant IHC, Manual

Specimen Type

Special

Specimen Stability Information

Specimen Type Temperature Time Special Container
Special Ambient (preferred)
  Refrigerated 

Reject Due To

Wet/frozen tissue
Decalcified paraffin embedded tissue
Cytology smears
Non-formalin fixed tissue including alcohol-formalin-acetic acid (AFA), 95% ethanol, PREFER fixatives or Zinc formalin
Nonparaffin embedded tissue
Noncharged slides
ProbeOn slides		 Reject

Clinical Information

Folate receptor 1 protein (FOLR1), also known as folate receptor alpha (FRa), is expressed in approximately 90% of ovarian carcinomas and serves as a predictive biomarker for FOLR1-targeted therapy for epithelial ovarian cancer. FOLR1 is a member of the folate receptor family that is reported to be highly expressed in various tumors of epithelial origin but has restricted expression in normal epithelial cells. Positivity for FOLR1 is expressed on greater or equal to 75% of viable tumor cells with moderate and/or strong membrane staining, while less than 75% of viable tumor cells with moderate and/or strong membrane staining is considered negative for FOLR1.

Reference Values

An interpretive report will be provided.

Interpretation

Folate receptor 1 protein (FOLR1) is a biomarker that, when positive (at least moderate membranous staining) in greater than or equal to 75% of tumor cells, predicts response to treatment with Elahere (mirvetuximab soravtansine) and has been approved for epithelial ovarian, fallopian tube, or primary peritoneal cancer.(1)

 

This result should be interpreted in the appropriate clinical context.

Cautions

This test has been validated for nondecalcified paraffin-embedded tissue specimens fixed in 10% neutral-buffered formalin. Recommended fixation time is between 6 hours and 48 hours. This assay has not been validated on tissues subjected to the decalcification process or use of alternative fixatives for bone and bone marrow specimens or cell blocks.

 

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.

Clinical Reference

1. VENTANA FOLR1 (FOR-2.1) RxDx Assay. US Package Insert. Roche Diagnostics; 2022

2. Scaranti M, Cojocaru E, Banerjee S, et al. Exploiting the folate receptor alpha in oncology. Nat Rev Clin Oncol. 2020;17(6):349-359

3. Necela B, Crozier J, Andorfer C, et al. Folate receptor-alpha (FOLR1) expression and function in triple negative tumors. PLoS One. 2015;10(3):e0122209

4. Kobel M, Madore J, Ramus S, et al. Evidence for a time-dependent association between FOLR1 expression and survival from ovarian carcinoma: implications for clinical testing. An Ovarian Tumour Tissue Analysis consortium study. Br J Cancer. 2014;111:2297-2307

Method Description

Immunohistochemistry on sections of paraffin-embedded tissue.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Report Available

5 to 7 days

Specimen Retention Time

Until reported

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

88360

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AFOLR FOLR1, SemiQuant IHC, Manual 105010-3

 

Result ID Test Result Name Result LOINC Value
620732 Interpretation 50595-8
621015 Participated in the Interpretation No LOINC Needed
621016 Report electronically signed by 19139-5
621017 Material Received 81178-6
621018 Disclaimer 62364-5
621019 Case Number 80398-1

Forms

If not ordering electronically, complete, print, and send an Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request (T763) with the specimen.