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LAG3 IHC Melanoma

CPT 88360

Test Details

Cancer Type

Melanoma

Use

The LAG3 assay is intended for use in the detection of LAG3 in formalin-fixed, paraffin-embedded (FFPE) tissue sections in melanoma.

Special Instructions

Please include a copy of the pathology report. Failure to do so may result in testing delays.

Limitations

Use of fixatives other than 10% formalin may not yield equivalent or satisfactory results.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Methodology

The LAG3 Immunohistochemistry Assay uses a mouse monoclonal anti-LAG3 antibody (clone 17B4) with the Leica Bond Polymer Refine Detection kit on Leica Bond III automated staining platform. LAG3 expression is assessed as the percentage of immune cells with positive staining that had a morphologic resemblance to lymphocytes within the tumor region (consisting of the tumor, intervening stroma, and invasive margin) relative to all nucleated cells in the tumor region in samples containing at least 100 viable tumor cells. A > or = to 1% cutoff is used to determine LAG-3 positivity.

Related Documents

References

Anderson AC, Joller N, Kuchroo VK. Lag-3, Tim-3, and TIGIT: Co-inhibitory Receptors with Specialized Functions in Immune Regulation. Immunity. 2016 May 17;44(5):989-1004.27192565
Dillon LM, Wojcik J, Desai K, et al. Abstract 1625: Distribution and prevalence of LAG-3 expression in samples of melanoma and gastric/gastroesophageal junction cancer. Cancer Res. 2021;81:Suppl 13:1625. doi.org/10.1158/1538-7445.AM2021-1625
Ruffo E, Wu RC, Bruno TC, Workman CJ, Vignali DAA. Lymphocyte-activation gene 3 (LAG3): The next immune checkpoint receptor. Semin Immunol. 2019 Apr;42:101305.31604537
Shen R, Postow MA, Adamow M, et al. LAG-3 expression on peripheral blood cells identifies patients with poorer outcomes after immune checkpoint blockade. Sci Transl Med. 2021 Aug 25;13(608):eabf5107.34433638
Tawbi HA, Schadendorf D, Lipson EJ, et al. Relatlimab and Nivolumab versus Nivolumab in Untreated Advanced Melanoma. N Engl J Med. 2022 Jan 6;386(1):24-34.34986285

Additional Information

Lymphocyte-activation gene 3 (LAG3) is an immune checkpoint receptor protein expressed on the cell surface of multiple immune cell types including effector T cells, regulatory T cells (Tregs), NK cells, B cells, and plasmacytoid dendritic cells. When engaged, LAG3 functions by delivering inhibitory signals that regulate immune cell homeostasis, T cell activation, proliferation, cytokine production, and cytolytic activity. Preclinical studies suggest that inhibiting LAG3 allows T cells to regain their cytotoxic function and potentially affect tumor growth. LAG3 expression is also being evaluated as a biomarker to predict response to treatment. Early research suggests that targeting the LAG3 pathway in combination with other potentially complementary immune pathways may be a key strategy to more effectively activate the antitumor immune response. In advanced melanoma, inhibition of LAG3 and PD-L1 provided improved progression-free survival than inhibition of PD-1 alone. While a >1% cutoff for LAG3 positivity is used for this test, there was also a benefit of the combination therapy in patients with <1% LAG3.

Specimen Requirements

Information on collection, storage, and volume

Specimen

Formalin fixed paraffin-embedded (FFPE) tissue

Volume

Paraffin block or 5 unstained slides

Minimum Volume

Paraffin block or 5 unstained slides

Container

Paraffin block or slide

Storage Instructions

Room temperature

Causes for Rejection

Insufficient tissue; tumor other than melanoma

Collection

Tissue should be fixed in 10% neutral buffered formalin for no more than 72 hours. Embed in paraffin.