PD-L1 testing based on SP142 antibody in metastatic triple-negative breast cancer: summary of an expert round-table discussion

PD-L1 testing

A recent Special Report published in Future Oncology presents the opinion of a group of experts on how to assess PD-L1 status using SP142 in patients with metastatic triple-negative breast cancer (mTNBC) in clinical practice. There are several PD-L1 assays used to select patients for immunotherapy, which have been developed independently for specific drugs and define the cut-off points for PD-L1-positive or -negative expression on tumor cells or on immune cells. An expert meeting was held at the end of 2019 to discuss the various methods for assessing expression of PD-L1 in patients with mTNBC. There was a focus on the VENTANA platform and the SP142 antibody clone as it is the only option with proven clinical utility for the selection of patients with mTNBC, who were candidates for treatment with atezolizumab. The article provides the questions and answers discussed at the meeting.


Triple-negative breast cancer (TNBC) is more aggressive than other breast cancer subtypes. TNBC is characterized by increased expression of PD-L1, a signal used by many tumors to escape the immune response. Expression of PD-L1 is a positive predictor of response to immunotherapy; therefore, it should be investigated in TNBC in order to select patients who may benefit from anti-PD-L1 therapies. While many PD-L1 assays are available, only the VENTANA platform with the anti-PD-L1 (SP142) antibody is licensed as a companion diagnostic device for selecting patients with metastatic/advanced TNBC who are candidates for treatment with atezolizumab. In this article, we provide a summary of an expert roundtable discussion about PD-L1 testing, using the SP142 antibody in metastatic TNBC.

Lay abstract

TNBC is the most aggressive breast cancer subtype. Recent discoveries in TNBC have shown that the higher the expression of the surface molecule PD-L1 in the cancer cells, the better the response of patients to immunotherapy. While several tests or diagnostics assays for detecting PD-L1 exist, only the antibody anti-PD-L1 SP142 possesses proven diagnostic value for selecting metastatic TNBC patients eligible for atezolizumab immunotherapy. Throughout the present article, a group of experts discusses how to best carry out the assessment of PD-L1 status with this assay.

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