Roche Holding AG said its Ventana assay received U.S. Food and Drug Administration approval to help identify breast cancer patients who could receive Tecentriq plus Abraxane.

The Swiss drugmaker said Ventana, or SP142 — a programmed death ligand 1, or PD-L1, assay that performs specific staining of tumor cells and immune cells — is now the first companion diagnostic that can be used to identify triple-negative breast cancer patients eligible for treatment with Tecentriq, or atezolizumab, in combination with Celgene Corp.'s chemotherapy drug Abraxane.

PD-L1 is a protein that helps the disease avoid the body's immune system. Tecentriq is part of a class of tumor-targeting drugs called checkpoint inhibitors, which block the PD-L1 protein on cancer cells from linking with a partner arm on healthy cells — an interaction that prevents the spread of the disease.

Ventana was developed to enhance visual contrast of tumor-infiltrating immune cell staining. In triple-negative breast cancer, PD-L1 is primarily expressed on tumor-infiltrating immune cells rather than on tumor cells themselves.

On March 8, Roche said the Tecentriq-Abraxane combo received accelerated approval to treat adults with triple-negative breast cancer, whose disease has worsened or has spread to other parts of the body and expresses the presence of PD-L1.

Triple-negative breast cancer is an aggressive form of breast cancer that does not have any of the receptors commonly found in breast cancer — estrogen, progesterone and excess human epidermal growth factor receptor 2. About 15% of breast cancers are triple-negative based on the results of diagnostic tests.

The Ventana assay was previously approved by the FDA for use as a companion diagnostic in urothelial carcinoma, a cancer of the bladder, and as a predictive assay in second-line non-small cell lung cancer with Tecentriq. The assay was used to enroll and stratify patients in Tecentriq clinical trials.