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Atezolizumab Shrinks Lung Tumors in Pivotal Trial

Monoclonal antibody activates T cells

A pivotal phase II study of atezolizumab (Genentech), an investigational cancer immunotherapy, met its primary endpoint (the objective response rate [ORR]) and shrank tumors in subjects with locally advanced or metastatic non–small-cell lung cancer (NSCLC) whose disease expressed programmed death ligand-1 (PDL-1). The study also showed that the amount of PDL-1 expressed by a subject’s cancer correlated with his or her response to treatment.

Atezolizumab is an investigational monoclonal antibody designed to interfere with the PDL-1 protein. The drug is designed to target PDL-1 expressed on tumor cells and on tumor-infiltrating immune cells, preventing the protein from binding to PDL-1 and B7.1 on the surface of T cells. By inhibiting PDL-1, atezolizumab may enable the activation of T cells.

The open-label, single-arm BIRCH trial evaluated the safety and efficacy of atezolizumab in 667 people with locally advanced or metastatic NSCLC whose disease expressed PDL-1. PDL-1 expression was assessed on both tumor cells and tumor-infiltrating immune cells with an investigational immunohistochemistry (IHC) test being developed by Roche Diagnostics. The test uses the antibody SP142 to measure PDL-1 expression.

Eligibility criteria included people whose tumors were determined to express PDL-1 with an IHC score of TC2/3 or IC2/3. The subjects received a 1,200-mg intravenous dose of atezolizumab every 3 weeks. The study’s primary endpoint was the ORR. Secondary endpoints included the duration of response, overall survival, progression-free survival, and safety.

Earlier this year, the FDA granted atezolizumab a “breakthrough therapy” designation for the treatment of patients whose NSCLC expressed PDL-1 and who progressed during or after standard treatments (e.g., platinum-based chemotherapy and appropriate targeted therapy for epidermal growth factor receptor [EGFR] mutation-positive or anaplastic lymphoma kinase [ALK]-positive disease). A “breakthrough therapy” designation is meant to expedite the development and review of medications intended to treat serious diseases.

Seven phase III studies are currently evaluating atezolizumab alone or in combination with other drugs as a potential treatment for patients with early or advanced stages of lung cancer.

According to the American Cancer Society, more than 221,000 Americans will be diagnosed with lung cancer in 2015. NSCLC accounts for 85% of all lung cancers.

Source: Genentech; August 16, 2015.

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