Complete response after rechallenge with trabectedin in a patient with previously responding high-grade undifferentiated sarcoma.

Evidence supporting rechallenge in patients responding to first exposure to trabectedin is limited. We report on a 39-year-old woman with advanced high-grade undifferentiated sarcoma (US) retreated twice with trabectedin after first response. The patient presented in June 2006 with an abdominal mass originating from the rear fascia of the rectus abdominis. Staging examinations did not indicate metastases and she underwent surgery; pathology showed a high-grade (FNCLCC G3) US. Subsequently, the patient received five cycles of adjuvant chemotherapy with epirubicin and ifosfamide. In February 2009 a computed tomography (CT) scan showed an abdominal mass involving the transverse mesocolon. R0 surgery was performed. In September 2009, peritoneal lesions appeared. Trabectedin was initiated at a dose of 1.5 mg/m by a 24 h intravenous infusion every 3 weeks, without relevant toxicity. After six cycles (March 2010), CT and PET-CT scans showed complete disappearance of metastases. In February 2012, new secondary lesions in the subdiaphragmatic region and a peritoneal lesion appeared. We rechallenged the patient with the same schedule of trabectedin; a complete response was achieved after two cycles. In October 2013, new secondary lesions in the subdiaphragmatic region and a retroperitoneal lesion were found. We rechallenged with the same schedule of trabectedin; PET-CT scans after two cycles showed complete response on the subdiaphragmatic lesion. Radiotherapy on the retroperitoneal lesion was performed. The patient underwent a total of 18 cycles and remains free from radiologically detectable disease. We report complete radiological remission after two rechallenges with trabectedin in a patient with previously responding high-grade US.