On December 9, 2022, the FDA approved atezolizumab (Tecentriq; Genentech), a PD-L1 inhibitor, for patients aged ≥2 years with unresectable or metastatic alveolar soft-part sarcoma (ASPS), a type of soft-tissue sarcoma. The FDA granted atezolizumab breakthrough therapy and orphan drug designations for this indication.
Atezolizumab was previously approved for many indications.
This new approval was based on Study ML39345, an open-label, single-arm trial of adult and pediatric patients with unresectable or metastatic ASPS. Patients were excluded if they had primary central nervous system (CNS) malignancy or symptomatic CNS metastases, liver disease, or a history of idiopathic pulmonary fibrosis, pneumonitis, organizing pneumonia, or active pneumonitis on imaging.
Of the 49 patients in the study, 47 were adults and 2 were pediatric patients (aged ≥12 years). Adult patients received atezolizumab 1200 mg intravenously and pediatric patients received 15 mg/kg (up to a maximum of 1200 mg) intravenously once every 21 days, until disease progression or unacceptable adverse events.
The overall response rate was 24% (95% confidence interval, 13-39). Among the 12 patients who had an objective response, 67% had a response lasting ≥6 months, and 42% had a response lasting ≥12 months.
The most common (≥20%) adverse events were musculoskeletal pain (67%); fatigue (55%); rash (47%); cough (45%); nausea, headache, and hypertension (43% each); vomiting (37%); constipation and dyspnea (33% each); dizziness and hemorrhage (29% each); insomnia and diarrhea (27% each); pyrexia, anxiety, abdominal pain, and hypothyroidism (25% each); and decreased appetite and arrhythmia (22% each).