Immune Checkpoint Inhibitor Approved for a Rare Sarcoma 

The FDA approved the PD-L1 inhibitor atezolizumab to treat alveolar soft part sarcoma 

The U.S. Food and Drug Administration has approved atezolizumab (Tecentriq) for the treatment of patients 2 years of age or older with alveolar soft part sarcoma (ASPS) that is metastatic or cannot be removed by surgery. 

Atezolizumab is in a class of therapies called immune checkpoint inhibitors, which help the immune system fight cancer. Atezolizumab is a monoclonal antibody that suppresses the function of PD-L1, a protein that masks the tumor from immune cells. When PD-L1 is blocked, tumor-fighting T cells can kill the tumor more efficiently. 

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The approval was based on results from ML39345, an open-label, single-arm clinical trial in which 49 patients (47 adults and two children aged 12 or older) with ASPS were treated with atezolizumab once every 21 days until disease progression or unacceptable side effects.  

The objective response rate was 24 percent. Among patients who experienced a response, 67 percent had a response lasting at least 6 months, and 42 percent had a response lasting at least 12 months. 

ASPS is one of the rarest sarcomas, with around 80 patients diagnosed in the U.S. each year. It is a slow-growing but fast-spreading cancer that can form in soft tissues such as muscle, fat, or nerves. 

The FDA rendered its decision on December 9, 2022.