On December 9, 2022, the Food and Drug Administration (FDA) approved atezolizumab for adult and paediatric patients 2 years of age and older with unresectable or metastatic alveolar soft part sarcoma (ASPS).

Efficacy was evaluated in study ML39345 (NCT03141684), an open-label, single-arm study in 49 adult and paediatric patients with unresectable or metastatic ASPS.

Eligible patients were required to have histologically or cytologically confirmed ASPS incurable by surgery and an ECOG performance status of ≤2.

Patients were excluded for primary central nervous system (CNS) malignancy or symptomatic CNS metastases, clinically significant liver disease, or a history of idiopathic pulmonary fibrosis, pneumonitis, organising pneumonia, or active pneumonitis on imaging.

Adult patients received 1200 mg intravenously and paediatric patients received 15 mg/kg (up to a maximum of 1200 mg) intravenously once every 21 days until disease progression or unacceptable toxicity.

The main efficacy outcome measures were overall response rate (ORR) and duration of response (DOR) determined by an independent review committee using RECIST v1.1. ORR was 24% (95% CI: 13, 39).

Of the 12 patients who experienced an objective response, 67% had a DOR of 6 months or more, and 42% had a DOR of 12 months or more.

The median patient age was 31 years (range: 12-70); 47 adult patients (2% were ≥65 years of age) and 2 paediatric patients ≥12 years of age were enrolled; 51% were female, 55% White, 29% Black or African American, 10% Asian.

The most common adverse reactions (≥15%) were musculoskeletal pain (67%); fatigue (55%); rash (47%); cough (45%); nausea, headache, and hypertension (43% each), vomiting (37%), constipation and dyspnoea (33% each), dizziness and haemorrhage (29% each), insomnia and diarrhoea (27% each), pyrexia, anxiety, abdominal pain and hypothyroidism (25% each), decreased appetite and arrhythmia (22% each), influenza-like illness and weight decreased (18% each), and allergic rhinitis and weight increased (16% each).

The recommended atezolizumab dosage for adult patients is 840 mg every 2 weeks, 1200 mg every 3 weeks, or 1680 mg every 4 weeks until disease progression or unacceptable toxicity.

The recommended dosage for paediatric patients 2 years of age and older is 15 mg/kg (up to a maximum of 1200 mg) every 3 weeks until disease progression or unacceptable toxicity.

View full prescribing information for atezolizumab here.

Source: US Food and Drug Administration