Epithelioid Sarcoma (EPIS)

Overview

Epithelioid sarcoma is a rare soft-tissue sarcoma characterized by loss of SMARCB1 (INI1) expression due to deletion/inactivation. It occurs in two forms: distal (classic, arising in the distal extremities of young adults) and proximal (more aggressive, associated with larger tumors in the axial region). It is classified under Soft Tissue Sarcoma in OncoTree (parent: SOFT_TISSUE).

Cohorts in the corpus

• sarcoma_ucla_2024: represented in the 24-subtype UCLA sarcoma PDTO biobank. SARC0075 was an epithelioid sarcoma with undifferentiated pleomorphic features that contributed multiple same-surgery metastatic samples demonstrating prominent intra-patient heterogeneity (194 specimens from 126 patients, Feb 2018–May 2022). PMID:39305899

Recurrent alterations

• ARID2, CRTC1, MAP3K1: shared SNVs across SARC0075’s four metastatic lesions, with extensive divergent copy-number variants including whole-genome duplications. PMID:39305899

Subtypes

• Distal (classic) epithelioid sarcoma
• Proximal epithelioid sarcoma (more aggressive)

Therapeutic landscape

• Intra-patient drug-response heterogeneity was prominent in EPIS: SARC0075 three same-surgery metastases showed Pearson correlations of 0.64–0.84 in drug-sensitivity profiles; SARC0075_2 responded to only 7.7% of regimens vs 23% for SARC0075_1/4. PMID:39305899
• tazemetostat (EZH2 inhibitor) is FDA-approved for SMARCB1-deficient EPIS in the broader literature (not directly tested in this study).

Sources

• PMID:39305899 — Al Shihabi et al. Cell Stem Cell 2024. UCLA sarcoma PDTO drug-sensitivity landscape.

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