Title: 503O_PR CIC-rearranged sarcoma and BCOR-CCNB3 sarcoma: Clinical characteristics and treatment results of the newly-established “Ewing sarcoma-like” small round cell sarcomas
Abstract: Background Recent molecular genetic analyses have disclosed that a subset of "Ewing sarcoma-like" small round cell sarcomas harbor CIC-DUX4, CIC-FOXO4 or BCOR- CCNB3 fusion gene in their tumor cells. The objective of this study is to clarify the clinical characteristics and treatment outcome of CIC-rearranged sarcoma (CIC sarcoma) and BCOR-CCNB3 sarcoma (BCOR sarcoma) because little is known about these newly-established sarcomas. Methods We retrieved 17 patients with CIC sarcoma and 7 patients with BCOR sarcoma diagnosed at our hospital. The clinical information was collected from the medical charts. Results The patients with CIC sarcoma were 12 males and 5 females, whereas all of the 7 patients with BCOR sarcoma were males. Ages at the initial visit ranged from 15 to 73 years (median 22 years) for CIC sarcoma; 4 to 16 years (median 12 years) for BCOR sarcoma. All of the 17 CIC sarcomas occurred in the soft tissue; 5 of the 7 BCOR sarcomas occurred in the bone. On images, all 17 CIC sarcomas presented lobular pattern, which was not evident in BCOR sarcomas. At the initial visit, 12 patients with CIC sarcoma had distant metastases to lung (n = 10), lymph node (n = 4), bone (n = 3), pleura (n = 3), and brain (n = 3), which were overlapped in some patients. In contrast, no patients with BCOR sarcoma had metastases atthe time of diagnosis. Surgerywas performed at 4 of the 5 patients with localized CIC sarcoma, resulting in no local recurrence. Chemotherapy was performed at all of the 12 patients with metastasized CIC sarcoma, using VDC/I(E) (n = 5), VAC (n = 3), AI (n = 2), or doxorubicin alone (n=2) asthefirst-lineregimen. Bestoverall responsewas CR(n= 1), PR(n=2), SD (n = 3), and PD (n = 6). Median overall survival of patients with CIC sarcoma was 10 months, and the clinical outcome was CDF (n = 3), NED (n = 1), AWD (n = 1), and DOD (n=12). TheoutcomeofBCORsarcomawas CDF (n=6) andAWD(n=1);no patients had died with a median follow-up of 64 months. Conclusions CIC and BCOR sarcomas show the distinctive clinical features and the different prognosis: BCOR sarcoma shows substantially better prognosis. The precise diagnosis of CIC or BCOR sarcoma leads to the suitable management based on the precise prognostic prediction. Legal entity responsible for the study N/A Funding Japanese Society for Promotion of Science Disclosure All authors have declared no conflicts of interest.