Desmoplastic Small Round Cell Tumors: Clinical Presentation, Molecular Characterization, and Therapeutic Approach of Seven Patients.

Desmoplastic small round blue cell tumor (DSRCT) is a highly aggressive fatal sarcoma without evidence-based therapeutic guidelines. We present here seven patients with DSRCT including immunohistochemistry combined with fluorescence in situ hybridization (FISH), next generation sequencing (NGS, n = 6) as well as OncoScan array (n = 3) analyses and show consecutive therapeutic approaches. All seven DSRCT patients presented with an extended abdominal mass; median age at diagnosis was 24.8 years. NGS analyses revealed five class 4 or 5 sequence variants. Remarkably, OncoScan and targeted analyses by FISH identified genomic gains of CCND1 in two cases. Cyclin D1 expression was present in all seven tumors as shown by immunohistochemical staining. Multimodal therapeutic concepts included systemic therapies, resection, and radiation. Six patients were treated as first-line therapy with conventional chemotherapy. All except one patient had a dismal therapy response. Subsequent therapy lines consisted of chemotherapeutic combinations followed by targeted therapies. Due to Cyclin D1 expression, the CDK4/6 inhibitor palbociclib was applied to four patients. The median therapy duration until disease progression in these patients was 4.5 months (range, 1.5-5 months). So, CCND1 genomic gain and Cyclin D1 expression are common features pointing to cell-cycle deregulation as a possible therapeutic target.