Atezolizumab Approved for Alveolar Soft Part Sarcoma

Alveolar soft part sarcoma micrograph.

The FDA has granted approval to atezolizumab (Tecentriq®, Genentech, Inc.) for treatment of unresectable or metastatic alveolar soft part sarcoma (ASPS) in patients two years of age and older. Atezolizumab is an immune checkpoint inhibitor targeting programmed cell death ligand 1 (PD-L1).

Safety and efficacy were measured in a phase 2, open-label, single-arm study (NCT03141684) which enrolled 49 patients with histologically or cytologically confirmed ASPS incurable by surgery and an Eastern Cooperative Oncology Group (ECOG) performance status of ≤2. Exclusion criteria included primary central nervous system (CNS) disease or symptomatic CNS metastases, clinically significant liver disease, or a history of idiopathic pulmonary fibrosis, pneumonitis, organizing pneumonia, or active pneumonitis on imaging. Adult patients were given 1200 mg intravenously once every 21 days, and pediatric patients were given 15 mg/kg, up to a maximum of 1200 mg, intravenously on the same 21-day cycle, until disease progression or unacceptable toxicity.

The primary end points measured were overall response rate and duration of response, as assessed by independent review committee using RECIST v1.1. Overall response rate was 24%. This included 12 patients achieving an objective response, of which 67% had a six-month or more duration of response, and 42% had a 12-month or more duration of response.

The most common adverse events in ≥15% of patients receiving atezolizumab were musculoskeletal pain, fatigue, rash, cough, nausea, headache, hypertension, vomiting, constipation, dyspnea, dizziness, hemorrhage, insomnia, diarrhea, pyrexia, anxiety, abdominal pain, hypothyroidism, decreased appetite and arrhythmia, influenza-like illness, weight increase/decrease, and allergic rhinitis.

The recommended dosage for adult patients receiving atezolizumab is 840 mg every two weeks, 1200 mg every three weeks, or 1680 mg every four weeks, until disease progression or unacceptable toxicity. The recommended dosage for pediatric patients two years of age and older is 15 mg/kg, with a maximum of up to 1200 mg, every three weeks until disease progression or unacceptable toxicity.

Resources (2022). Testing atezolizumab alone or atezolizumab plus bevacizumab in people with advanced alveolar soft part sarcoma. NLM identifier: NCT03141684

Tecentriq® (atezolizumab) prescribing information (2022). Genentech Inc. Available at:

US Food and Drug Administration (2022). FDA grants approval to atezolizumab for alveolar soft part sarcoma. Available at: 

Image credit: Nephron. Licensed under CC BY-SA 3.0

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