Rechallenge of carboplatin-gemcitabine based chemotherapy for rapidly progressing metastatic collecting duct carcinoma of the kidney leading to a delayed and durable complete response: A case report.

Renal collecting duct carcinoma (CDC) is a rare and highly aggressive subtype of kidney cancer with poor prognosis. We report a case of one patient, who was successfully treated with gemcitabine-platin based chemotherapy for polymetastatic renal CDC, and experienced a late and prolonged complete remission. In June 2014, a 69-year-old male patient was diagnosed with non-metastatic renal CDC. Nephrouretectomy was firstly performed. In December 2014, he developed a loco-regional recurrence with bilateral lung metastases. The patient started a course of gemcitabine-carboplatin (GC)-based first-line chemotherapy and received 6 cycles, which ended in May 2015. Computed tomography (CT) scan evaluation displayed an objective response according to RECIST 1.1 criteria and a follow-up of the patient was conducted. In August 2015, he had a second local relapse with new lung metastases. Despite a short disease-free interval, 6 cycles of the same GC regimen were required, which ended in February 2016. The patient firstly exhibited a partial objective response after the first 3 cycles and a stable disease at the end of chemotherapy. During the follow-up, a CT scan of his chest, abdomen and pelvis was performed every 3 months. From September 2016 to May 2017, despite no new specific treatments for his metastatic disease, the patient again experienced an objective and confirmed response on each CT-scan evaluation until complete remission in May 2017. This case report highlights the efficacy of GC-based chemotherapy, which is able to provide a durable and sometimes complete response in metastatic renal CDC, and suggests the potential of rechallenging with the same chemotherapy regimen, despite a short disease-free interval. The originality of this case was demonstrated by the delayed complete response more than one year after the end of GC-based second line chemotherapy. The patient remained disease-free at his last CT-scan evaluation in April 2018.