While alveolar soft part sarcoma (ASPS) is considered to be relatively slow-growing, it is necessary to carefully manage this rare soft tissue sarcoma to avoid metastasizing. Surgery is one of the top standards-of-care for those with this condition. Recently, the FDA approved a new therapeutic option for adults and children aged 2+ with unresectable (not surgically removable) or metastatic ASPS (where the cancer has spread). This option is Tecentriq (atezolizumab), a monoclonal antibody medication. 

According to OncLive, Tecentriq was shown to benefit both pediatric and adult patients within a Phase 2 clinical trial called Study ML39345. Participants (47 adults and 2 children) received 1200mg or 15mg/kg intravenous Tecentriq daily. The participants stayed on this treatment regimen until their condition progressed or they reached a point of toxicity. Prior to the study, 100% of participants had undergone surgery and 55% had undergone at least one other line of therapy. 

Findings showed that:

• 67% of patients experienced a response to treatment that lasted for at least six months. 42% had a response lasting for 12+ months.
• There were a number of common side effects associated with Tecentriq, including weight gain and weight loss, fatigue, rash, musculoskeletal pain, cough, nausea and vomiting, diarrhea or constipation, headache, dizziness, abdominal pain, and arrhythmias (among others). 41% of the participants in the trial experienced severe adverse reactions.

With the approval, the new recommended therapeutic dose is 840mg every two weeks, 1200mg every three weeks, or 1680mg monthly for adults, and 15mg/kg every three weeks for children. 

What is Alveolar Soft Part Sarcoma? 

Alveolar soft part sarcoma is a rare soft tissue tumor that often arises in the leg or buttock, but may also be found in the arm, neck, or head. In children, it is more often found in the tongue and eye socket. By the time ASPS is diagnosed, it has often spread to areas like the lungs or bones. The National Organization for Rare Disorders (NORD) shares that

‘This disorder is very rare because it involves a specific breaking and joining event between two chromosomes, called an ‘unbalanced translocation.’

This finding is observed in essentially all people with ASPS examined so far.

Alveolar soft part sarcoma tends to occur in younger individuals. Females are also more likely to develop ASPS than males. 

Symptoms and characteristics related to ASPS can include:

• A painless mass on the thigh or buttock
• Limping or other movement difficulties
• Pleural effusion
• Headache
• Bone fractures
• Cough
• Sharp chest pain

Treatment options include chemotherapy, surgery, radiation therapy, and targeted therapy.