Therapeutic Challenges in the Management of Collecting Duct Carcinoma of the Kidney: A Case Report with Review of Literature

Abstract Collecting duct carcinoma (CDC) of the kidney is a rare type of renal cell carcinoma. It is an aggressive tumor with a poor prognosis and limited treatment options. A 67-year-old man, during evaluation for hematuria, loss of appetite and weight loss, and flank pain, was found to have a left renal mass with lung and bone metastasis. He underwent a left radical nephrectomy, and histopathological examination confirmed CDC. He received palliative chemotherapy with carboplatin and gemcitabine. Computed tomography (CT) scan after three cycles showed partial response. Chemotherapy was stopped due to worsening renal function after five cycles. Immunohistochemical studies done for programmed cell death ligand 1(PDL1) SP263 and Her2 neu were negative. Next-generation sequencing for 75 therapeutically actionable gene panels showed loss of function mutation in the neurofibromatosis type 1 (NF1) gene. Missense mutations involving Platelet derived growth factor receptor alpha gene (PDGFRA), FAT atypical cadherin 1 (FAT1), and Androgen receptor (AR) genes were reported as variants of unknown significance. No clinically relevant alterations were detected in liquid biopsy. Consequently, he was started on sunitinib. After 2 months, he developed brain metastasis and was treated with whole brain radiation therapy. Systemic therapy was changed to single-agent Nab-paclitaxel. After three cycles, he developed a cutaneous metastasis in the forearm and chemotherapy was changed to single-agent doxorubicin. After three cycles of doxorubicin, he succumbed to the disease. He survived for 16 months after diagnosis. The first-line treatment for metastatic CDC is chemotherapy with gemcitabine and cisplatin. There is no established second-line treatment. In this era, next-generation sequencing for targetable genetic alterations can help us select the treatment for subsequent lines of therapy.