Collecting duct carcinoma of the kidney is a rare and aggressive neoplasm of the distal collecting tubules for which there is no established treatment. Since the histology of collecting duct carcinoma is similar to that of urothelial carcinoma, the standard chemotherapy regimen defined by a gemcitabine and platinum salts combination was prospectively investigated in patients with metastatic collecting duct carcinoma. A total of 23 patients with metastatic collecting duct carcinoma with no prior systemic chemotherapy were treated with 1,250 mg/m(2) gemcitabine on days 1 and 8 plus 70 mg/m(2) cisplatin or carboplatin (AUC 5) in patients with renal insufficiency on day 1. The drugs were repeated every 21 days for 6 cycles according to toxicity and efficacy. The objective response rate was the primary end point. There were 1 complete and 5 partial responses for an objective response rate of 26% (95% CI 8 to 44). Median progression-free and overall survival was 7.1 (95% CI 3 to 11.3) and 10.5 months (95% CI 3.8 to 17.1), respectively. Toxicity was mainly hematological with grade 3-4 neutropenia and thrombocytopenia in 52% and 43% of patients, respectively. The severity of granulocytopenia and the number of metastatic sites were associated with overall survival on univariate and multivariate analyses. To our knowledge this is the first prospective, multicenter, phase II study showing that the platinum salts combination is an active and safe regimen as first line treatment in patients with metastatic collecting duct carcinoma. This platinum based chemotherapy should be considered the standard regimen in these patients.

Immune checkpoint inhibitors (ICI) represent the cornerstone for the treatment of patients with metastatic clear cell renal cell carcinoma (ccRCC). Despite a favorable response for a subset of patients, others experience primary progressive disease, highlighting the need to precisely understand the plasticity of cancer cells and their cross-talk with the microenvironment to better predict therapeutic response and personalize treatment. Single-cell RNA sequencing of ccRCC at different disease stages and normal adjacent tissue (NAT) from patients identified 46 cell populations, including 5 tumor subpopulations, characterized by distinct transcriptional signatures representing an epithelial-to-mesenchymal transition gradient and a novel inflamed state. Deconvolution of the tumor and microenvironment signatures in public data sets and data from the BIONIKK clinical trial (NCT02960906) revealed a strong correlation between mesenchymal-like ccRCC cells and myofibroblastic cancer-associated fibroblasts (myCAF), which are both enriched in metastases and correlate with poor patient survival. Spatial transcriptomics and multiplex immune staining uncovered the spatial proximity of mesenchymal-like ccRCC cells and myCAFs at the tumor–NAT interface. Moreover, enrichment in myCAFs was associated with primary resistance to ICI therapy in the BIONIKK clinical trial. These data highlight the epithelial–mesenchymal plasticity of ccRCC cancer cells and their relationship with myCAFs, a critical component of the microenvironment associated with poor outcome and ICI resistance. Significance: Single-cell and spatial transcriptomics reveal the proximity of mesenchymal tumor cells to myofibroblastic cancer-associated fibroblasts and their association with disease outcome and immune checkpoint inhibitor response in clear cell renal cell carcinoma.

The complement system is a powerful and druggable innate immune component of the tumor microenvironment. Nevertheless, it is challenging to elucidate the exact mechanisms by which complement affects tumor growth. In this study, we examined the processes by which the master complement regulator factor H (FH) affects clear cell renal cell carcinoma (ccRCC) and lung cancer, two cancers in which complement overactivation predicts poor prognosis. FH was present in two distinct cellular compartments: the membranous (mb-FH) and intracellular (int-FH) compartments. Int-FH resided in lysosomes and colocalized with C3. In ccRCC and lung adenocarcinoma, FH exerted protumoral action through an intracellular, noncanonical mechanism. FH silencing in ccRCC cell lines resulted in decreased proliferation, due to cell-cycle arrest and increased mortality, and this was associated with increased p53 phosphorylation and NFκB translocation to the nucleus. Moreover, the migration of the FH-silenced cells was reduced, likely due to altered morphology. These effects were cell type–specific because no modifications occurred upon CFH silencing in other FH-expressing cells tested: tubular cells (from which ccRCC originates), endothelial cells (human umbilical vein endothelial cells), and squamous cell lung cancer cells. Consistent with this, in ccRCC and lung adenocarcinoma, but not in lung squamous cell carcinoma, int-FH conferred poor prognosis in patient cohorts. Mb-FH performed its canonical function of complement regulation but had no impact on tumor cell phenotype or patient survival. The discovery of intracellular functions for FH redefines the role of the protein in tumor progression and its use as a prognostic biomarker or potential therapeutic target.See article by Daugan et al., p. 891 (36).

For patients with metastatic castration-resistant prostate cancer (mCRPC), the current standard of care is chemotherapy involving the tubulin-binding taxane docetaxel. However, as the tumor cells become resistant to docetaxel-based therapy, disease progression is inevitable, and until recently there was no further available treatment beyond palliative care. In June 2010, cabazitaxel, a next-generation taxane, was approved by the US FDA for the treatment of mCRPC that has progressed after docetaxel therapy. This article describes the background and rationale of cabazitaxel's development and the clinical study program that led to its FDA approval, focusing on the Phase III TROPIC trial that demonstrated the efficacy of cabazitaxel plus prednisone in the treatment of mCRPC. Future development of this therapy and others under investigation is discussed.