Molecular and therapeutic landscape of non-clear cell renal carcinoma

Non-clear cell renal cell carcinomas (nccRCC) include diverse subtypes such as papillary, oncocytic and chromophobe, collecting duct, molecularly defined and other rare histological subtypes, each associated with unique clinical, pathological, genetic and molecular features as well as therapeutic challenges. Surgical resection remains the primary approach for the treatment of localized nccRCC but optimal outcomes depend on tumour stage and the patient’s overall health. Clinically established treatment guidelines tailored for patients diagnosed with nccRCC are limited owing to the molecular and histological heterogeneity of nccRCC. Progress has been made in systemic therapy for metastatic disease but nccRCC treatment still poses challenges as patients experience variable treatment responses to immunotherapy, targeted therapies, chemotherapy and some combination strategies. Molecular biomarkers as well as established techniques, such as immunohistochemical and genetic analysis, have a crucial role in early detection, prognosis prediction and personalization of targeted therapies for nccRCC. The increasing identification of potential signatures and actionable molecular targets will aid in the clinical decision-making for patients diagnosed with these rare tumours towards optimization of the therapeutic response and treatment outcomes. This Review discusses the different subtypes of non-clear cell renal cell carcinoma in terms of molecular, genetic and clinicopathological characteristics as well as response to therapy. The authors highlight challenges associated with the rarity and heterogeneity of this subset of tumours and how investing in future research to find reliable biomarkers will be essential to improve patient outcomes.