Advances and Challenges in Pediatric Alveolar Soft Part Sarcoma


Jeffrey Dome, MD, PhD, discusses how the use of atezolizumab has impacted the treatment of pediatric patients with alveolar soft part sarcoma.

Jeffrey Dome, MD, PhD, senior vice president of the Center of Cancer and Blood Disorders and the division chief of oncology at the Children’s National Medical Center, highlights the rarity of treating pediatric patients with alveolar soft part sarcoma and the remaining challenges even with new therapies available.

In 2022, the FDA approved atezolizumab (Tecentriq) for the treatment of adult and pediatric patients aged 2 years or older with unresectable or metastatic alveolar soft part sarcoma. The approval was based on data from the open-label, single-arm, ML39345 (NCT03141684) study which met its primary end point of overall response rate (ORR) and duration of response (DOR). ORR among the 49 patients on the trial was 24% (95% CI, 13%-39%) and of the 12 patients who had an objective response 67% had a DOR of 6 months or more. Moreover, 42% of these patients had a DOR of 12 months or more.

However, patients who get this disease and are metastatic have a poor survival rate, according to Dome. The prognosis of patients with metastatic alveolar soft part sarcoma makes treatment more difficult. Dome discusses these challenges and how the PD-1 inhibitor works within these patients to combat the disease.


0:08 | We don't see a lot of alveolar soft part sarcoma; it is very uncommon in the pediatric population. Occasionally, we see [these] patients and when these patients have metastatic disease the prognosis is very poor, again with survival rates less than 20%. So, this is a tumor that isn't very sensitive to chemotherapy. So, it's 1 of the typical sarcomas where we have to come up with better treatments [for].

0:42 | So, it's very promising that atezolizumab was approved by the FDA to treat a relatively rare tumor. The way that drug works is that it's in the class of immune checkpoint inhibitors that target the PD-1 pathway. And what they do, essentially, is they activate the immune system to fight the cancer by blocking one of the blockers of the immune system. So, it's a double negative, and thereby that activates the immune system. So, the results with alveolar soft parts sarcoma were promising.

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