Real world outcomes in alveolar soft part sarcomas: experience with an ultra-rare sarcoma from a tertiary care centre in North India.

Background: Alveolar soft part sarcoma (ASPS) is a rare, indolent soft tissue sarcoma, with a high predilection for systemic dissemination. This study aims to elucidate the patterns of clinical presentation of ASPS and their treatment outcomes, with emphasis on the use of newer therapeutic agents and their efficacy in advanced ASPS. Methods: This was a retrospective cohort that included patients with ASPS treated at our institute between 2016 and 2023. Clinicopathological data were obtained from case records and analysed to assess outcomes. Results: The study included 34 patients (19 males, 15 females) with a median age of 28 (3-72) years. 7 patients presented with localised disease, and 27 with metastatic disease. The most common site of primary was the extremities (73%), and the most common sites of metastasis included the lungs (82%) and bones (21%). Brain metastasis was seen in 7 patients at baseline (25.9%). 90% of patients with metastatic disease received a tyrosine kinase inhibitor in the first-line setting with a median progression-free survival of 12 months. The median overall survival in this subset was 36 months. 7 patients with the advanced disease received immune-checkpoint inhibitors (ICIs) (3-atezolizumab, 4-nivolumab); 2 patients on atezolizumab and 1 on nivolumab continue to be progression free at 20,15 and 52 months, respectively. Patients with brain metastasis were seen to have markedly poor outcomes. Conclusion: The use of anti-angiogenic agents and ICIs has significantly improved survival in patients with advanced ASPS. Brain metastasis confers poor survival in these patients despite the use of newer agents. This study represents the largest cohort of patients with advanced ASPS from this region.