TFCP2 Fusion-Positive Rhabdomyosarcomas: A Report of 10 Cases and a Review of the Literature

Background/Objectives: The fusion of the TFCP2 gene with either EWSR1 or FUS typically results in a spindle cell and/or epithelioid variant of rhabdomyosarcoma. This is an ultra-rare type of sarcoma, with most of our knowledge about these coming from case reports and small case series. Herein, we describe the clinical characteristics and treatment course of 10 patients with TFCP2 fusion sarcomas. Methods: We identified 10 patients in our hospital system with TFCP2 fusion sarcomas and 43 previously reported cases in the literature. We assessed primary tumor characteristics, treatment regimens, and survival rates among all cases. Results: We find that TFCP2 fusion sarcomas most commonly occur in young adults (median age: 33 years) and arise in craniofacial bones (7/10, 70%). Concomitant ALK alterations and ALK overexpression is nearly universal, and two of our patients were treated with ALK inhibitors; one patient had a near complete response before eventual progression, while the other patient had progressive disease after 2 months. For most, the prognosis was poor. The median overall survival in this cohort was 24.7 months (range: 5.9-29.7 months). Four patients were treated with upfront surgery, and all four developed recurrent disease. The median time to recurrence following upfront surgery was 2.1 months (range: 0.73-6.9 months). Five patients received systemic therapy, and the median progression-free survival from the start of treatment to progression was 1.6 months (range: 0.97-2.7). We also review the 53 total cases of TFCP2 fusion sarcomas in the literature, again highlighting the dismal outcomes in this disease. Conclusions:TFCP2 fusion sarcomas are proven to be aggressive and have poor prognosis. Additional work is needed to define the optimal treatment course for TFCP2 fusion sarcomas.