Michigan Center for Translational Pathology

BACKGROUND: Patients with diffuse large B-cell lymphoma that is refractory to primary and second-line therapies or that has relapsed after stem-cell transplantation have a poor prognosis. The chimeric antigen receptor (CAR) T-cell therapy tisagenlecleucel targets and eliminates CD19-expressing B cells and showed efficacy against B-cell lymphomas in a single-center, phase 2a study. METHODS: We conducted an international, phase 2, pivotal study of centrally manufactured tisagenlecleucel involving adult patients with relapsed or refractory diffuse large B-cell lymphoma who were ineligible for or had disease progression after autologous hematopoietic stem-cell transplantation. The primary end point was the best overall response rate (i.e., the percentage of patients who had a complete or partial response), as judged by an independent review committee. RESULTS: A total of 93 patients received an infusion and were included in the evaluation of efficacy. The median time from infusion to data cutoff was 14 months (range, 0.1 to 26). The best overall response rate was 52% (95% confidence interval, 41 to 62); 40% of the patients had complete responses, and 12% had partial responses. Response rates were consistent across prognostic subgroups. At 12 months after the initial response, the rate of relapse-free survival was estimated to be 65% (79% among patients with a complete response). The most common grade 3 or 4 adverse events of special interest included cytokine release syndrome (22%), neurologic events (12%), cytopenias lasting more than 28 days (32%), infections (20%), and febrile neutropenia (14%). Three patients died from disease progression within 30 days after infusion. No deaths were attributed to tisagenlecleucel, cytokine release syndrome, or cerebral edema. No differences between response groups in tumor expression of CD19 or immune checkpoint-related proteins were found. CONCLUSIONS: In this international study of CAR T-cell therapy in relapsed or refractory diffuse large B-cell lymphoma in adults, high rates of durable responses were produced with the use of tisagenlecleucel. (Funded by Novartis; JULIET ClinicalTrials.gov number, NCT02445248 .).

Abstract Somatic mutations in cancer genomes are caused by multiple mutational processes, each of which generates a characteristic mutational signature 1 . Here, as part of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium 2 of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA), we characterized mutational signatures using 84,729,690 somatic mutations from 4,645 whole-genome and 19,184 exome sequences that encompass most types of cancer. We identified 49 single-base-substitution, 11 doublet-base-substitution, 4 clustered-base-substitution and 17 small insertion-and-deletion signatures. The substantial size of our dataset, compared with previous analyses 3–15 , enabled the discovery of new signatures, the separation of overlapping signatures and the decomposition of signatures into components that may represent associated—but distinct—DNA damage, repair and/or replication mechanisms. By estimating the contribution of each signature to the mutational catalogues of individual cancer genomes, we revealed associations of signatures to exogenous or endogenous exposures, as well as to defective DNA-maintenance processes. However, many signatures are of unknown cause. This analysis provides a systematic perspective on the repertoire of mutational processes that contribute to the development of human cancer.

BACKGROUND: Mitoxantrone-based chemotherapy palliates pain without extending survival in men with progressive androgen-independent prostate cancer. We compared docetaxel plus estramustine with mitoxantrone plus prednisone in men with metastatic, hormone-independent prostate cancer. METHODS: We randomly assigned 770 men to one of two treatments, each given in 21-day cycles: 280 mg of estramustine three times daily on days 1 through 5, 60 mg of docetaxel per square meter of body-surface area on day 2, and 60 mg of dexamethasone in three divided doses before docetaxel, or 12 mg of mitoxantrone per square meter on day 1 plus 5 mg of prednisone twice daily. The primary end point was overall survival; secondary end points were progression-free survival, objective response rates, and post-treatment declines of at least 50 percent in serum prostate-specific antigen (PSA) levels. RESULTS: Of 674 eligible patients, 338 were assigned to receive docetaxel and estramustine and 336 to receive mitoxantrone and prednisone. In an intention-to-treat analysis, the median overall survival was longer in the group given docetaxel and estramustine than in the group given mitoxantrone and prednisone (17.5 months vs. 15.6 months, P=0.02 by the log-rank test), and the corresponding hazard ratio for death was 0.80 (95 percent confidence interval, 0.67 to 0.97). The median time to progression was 6.3 months in the group given docetaxel and estramustine and 3.2 months in the group given mitoxantrone and prednisone (P<0.001 by the log-rank test). PSA declines of at least 50 percent occurred in 50 percent and 27 percent of patients, respectively (P<0.001), and objective tumor responses were observed in 17 percent and 11 percent of patients with bidimensionally measurable disease, respectively (P=0.30). Grade 3 or 4 neutropenic fevers (P=0.01), nausea and vomiting (P<0.001), and cardiovascular events (P=0.001) were more common among patients receiving docetaxel and estramustine than among those receiving mitoxantrone and prednisone. Pain relief was similar in both groups. CONCLUSIONS: The improvement in median survival of nearly two months with docetaxel and estramustine, as compared with mitoxantrone and prednisone, provides support for this approach in men with metastatic, androgen-independent prostate cancer.

Abstract Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale 1–3 . Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4–5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter 4 ; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation 5,6 ; analyses timings and patterns of tumour evolution 7 ; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity 8,9 ; and evaluates a range of more-specialized features of cancer genomes 8,10–18 .

BACKGROUND: Androgen-deprivation therapy (ADT) has been the backbone of treatment for metastatic prostate cancer since the 1940s. We assessed whether concomitant treatment with ADT plus docetaxel would result in longer overall survival than that with ADT alone. METHODS: We assigned men with metastatic, hormone-sensitive prostate cancer to receive either ADT plus docetaxel (at a dose of 75 mg per square meter of body-surface area every 3 weeks for six cycles) or ADT alone. The primary objective was to test the hypothesis that the median overall survival would be 33.3% longer among patients receiving docetaxel added to ADT early during therapy than among patients receiving ADT alone. RESULTS: A total of 790 patients (median age, 63 years) underwent randomization. After a median follow-up of 28.9 months, the median overall survival was 13.6 months longer with ADT plus docetaxel (combination therapy) than with ADT alone (57.6 months vs. 44.0 months; hazard ratio for death in the combination group, 0.61; 95% confidence interval [CI], 0.47 to 0.80; P<0.001). The median time to biochemical, symptomatic, or radiographic progression was 20.2 months in the combination group, as compared with 11.7 months in the ADT-alone group (hazard ratio, 0.61; 95% CI, 0.51 to 0.72; P<0.001). The rate of a prostate-specific antigen level of less than 0.2 ng per milliliter at 12 months was 27.7% in the combination group versus 16.8% in the ADT-alone group (P<0.001). In the combination group, the rate of grade 3 or 4 febrile neutropenia was 6.2%, the rate of grade 3 or 4 infection with neutropenia was 2.3%, and the rate of grade 3 sensory neuropathy and of grade 3 motor neuropathy was 0.5%. CONCLUSIONS: Six cycles of docetaxel at the beginning of ADT for metastatic prostate cancer resulted in significantly longer overall survival than that with ADT alone. (Funded by the National Cancer Institute and others; ClinicalTrials.gov number, NCT00309985.).

Cancer genomic, transcriptomic, and proteomic profiling has generated extensive data that necessitate the development of tools for its analysis and dissemination. We developed UALCAN to provide a portal for easy exploring, analyzing, and visualizing these data, allowing users to integrate the data to better understand the gene, proteins, and pathways perturbed in cancer and make discoveries. UALCAN web portal enables analyzing and delivering cancer transcriptome, proteomics, and patient survival data to the cancer research community. With data obtained from The Cancer Genome Atlas (TCGA) project, UALCAN has enabled users to evaluate protein-coding gene expression and its impact on patient survival across 33 types of cancers. The web portal has been used extensively since its release and received immense popularity, underlined by its usage from cancer researchers in more than 100 countries. The present manuscript highlights the task we have undertaken and updates that we have made to UALCAN since its release in 2017. Extensive user feedback motivated us to expand the resource by including data on a) microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and promoter DNA methylation from TCGA and b) mass spectrometry-based proteomics from the Clinical Proteomic Tumor Analysis Consortium (CPTAC). UALCAN provides easy access to pre-computed, tumor subgroup-based gene/protein expression, promoter DNA methylation status, and Kaplan-Meier survival analyses. It also provides new visualization features to comprehend and integrate observations and aids in generating hypotheses for testing. UALCAN is accessible at http://ualcan.path.uab.edu.

BAD is a distant member of the Bcl-2 family that promotes cell death. Phosphorylation of BAD prevents this. BAD phosphorylation induced by interleukin-3 (IL-3) was inhibited by specific inhibitors of phosphoinositide 3-kinase (PI 3-kinase). Akt, a survival-promoting serine-threonine protein kinase, was activated by IL-3 in a PI 3-kinase-dependent manner. Active, but not inactive, forms of Akt were found to phosphorylate BAD in vivo and in vitro at the same residues that are phosphorylated in response to IL-3. Thus, the proapoptotic function of BAD is regulated by the PI 3-kinase-Akt pathway.

Oesophageal cancers are prominent worldwide; however, there are few targeted therapies and survival rates for these cancers remain dismal. Here we performed a comprehensive molecular analysis of 164 carcinomas of the oesophagus derived from Western and Eastern populations. Beyond known histopathological and epidemiologic distinctions, molecular features differentiated oesophageal squamous cell carcinomas from oesophageal adenocarcinomas. Oesophageal squamous cell carcinomas resembled squamous carcinomas of other organs more than they did oesophageal adenocarcinomas. Our analyses identified three molecular subclasses of oesophageal squamous cell carcinomas, but none showed evidence for an aetiological role of human papillomavirus. Squamous cell carcinomas showed frequent genomic amplifications of CCND1 and SOX2 and/or TP63, whereas ERBB2, VEGFA and GATA4 and GATA6 were more commonly amplified in adenocarcinomas. Oesophageal adenocarcinomas strongly resembled the chromosomally unstable variant of gastric adenocarcinoma, suggesting that these cancers could be considered a single disease entity. However, some molecular features, including DNA hypermethylation, occurred disproportionally in oesophageal adenocarcinomas. These data provide a framework to facilitate more rational categorization of these tumours and a foundation for new therapies. The Cancer Genome Atlas Research Network report integrated genomic and molecular analyses of 164 squamous cell carcinomas and adenocarcinomas of the oesophagus; they find genomic and molecular features that differentiate squamous and adenocarcinomas of the oesophagus, and strong similarities between oesophageal adenocarcinomas and the chromosomally unstable variant of gastric adenocarcinoma, suggesting that gastroesophageal adenocarcinoma is a single disease entity. The Cancer Genome Atlas Research Network reports integrated genomic and molecular analyses of 164 squamous cell carcinomas and adenocarcinomas of the oesophagus. They identify genomic and molecular features that differentiate oesophageal squamous cell carcinomas from oesophageal adenocarcinomas. They find that the genomic profiles of oesophageal adenocarcinomas are more similar to those for gastric adenocarcinoma, suggesting that these might be classified together. Separate consideration of adenocarcinoma and squamous cell carcinoma—and further molecular characterization of these cancers—may be helpful in clinical trials and for developing targeted drug therapies.

Abstract The discovery of numerous noncoding RNA (ncRNA) transcripts in species from yeast to mammals has dramatically altered our understanding of cell biology, especially the biology of diseases such as cancer. In humans, the identification of abundant long ncRNA (lncRNA) &amp;gt;200 bp has catalyzed their characterization as critical components of cancer biology. Recently, roles for lncRNAs as drivers of tumor suppressive and oncogenic functions have appeared in prevalent cancer types, such as breast and prostate cancer. In this review, we highlight the emerging impact of ncRNAs in cancer research, with a particular focus on the mechanisms and functions of lncRNAs. Significance: lncRNAs represent the leading edge of cancer research. Their identity, function, and dysregulation in cancer are only beginning to be understood, and recent data suggest that they may serve as master drivers of carcinogenesis. Increased research on these RNAs will lead to a greater understanding of cancer cell function and may lead to novel clinical applications in oncology. Cancer Discovery; 1(5): 391–407. ©2011 AACR.

BACKGROUND: The administration of endocrine therapy for 5 years substantially reduces recurrence rates during and after treatment in women with early-stage, estrogen-receptor (ER)-positive breast cancer. Extending such therapy beyond 5 years offers further protection but has additional side effects. Obtaining data on the absolute risk of subsequent distant recurrence if therapy stops at 5 years could help determine whether to extend treatment. METHODS: In this meta-analysis of the results of 88 trials involving 62,923 women with ER-positive breast cancer who were disease-free after 5 years of scheduled endocrine therapy, we used Kaplan-Meier and Cox regression analyses, stratified according to trial and treatment, to assess the associations of tumor diameter and nodal status (TN), tumor grade, and other factors with patients' outcomes during the period from 5 to 20 years. RESULTS: Breast-cancer recurrences occurred at a steady rate throughout the study period from 5 to 20 years. The risk of distant recurrence was strongly correlated with the original TN status. Among the patients with stage T1 disease, the risk of distant recurrence was 13% with no nodal involvement (T1N0), 20% with one to three nodes involved (T1N1-3), and 34% with four to nine nodes involved (T1N4-9); among those with stage T2 disease, the risks were 19% with T2N0, 26% with T2N1-3, and 41% with T2N4-9. The risk of death from breast cancer was similarly dependent on TN status, but the risk of contralateral breast cancer was not. Given the TN status, the factors of tumor grade (available in 43,590 patients) and Ki-67 status (available in 7692 patients), which are strongly correlated with each other, were of only moderate independent predictive value for distant recurrence, but the status regarding the progesterone receptor (in 54,115 patients) and human epidermal growth factor receptor type 2 (HER2) (in 15,418 patients in trials with no use of trastuzumab) was not predictive. During the study period from 5 to 20 years, the absolute risk of distant recurrence among patients with T1N0 breast cancer was 10% for low-grade disease, 13% for moderate-grade disease, and 17% for high-grade disease; the corresponding risks of any recurrence or a contralateral breast cancer were 17%, 22%, and 26%, respectively. CONCLUSIONS: After 5 years of adjuvant endocrine therapy, breast-cancer recurrences continued to occur steadily throughout the study period from 5 to 20 years. The risk of distant recurrence was strongly correlated with the original TN status, with risks ranging from 10 to 41%, depending on TN status and tumor grade. (Funded by Cancer Research UK and others.).

The gene encoding the Nod2 protein is frequently mutated in Crohn's disease (CD) patients, although the physiological function of Nod2 in the intestine remains elusive. Here we show that protective immunity mediated by Nod2 recognition of bacterial muramyl dipeptide is abolished in Nod2-deficient mice. These animals are susceptible to bacterial infection via the oral route but not through intravenous or peritoneal delivery. Nod2 is required for the expression of a subgroup of intestinal anti-microbial peptides, known as cryptdins. The Nod2 protein is thus a critical regulator of bacterial immunity within the intestine, providing a possible mechanism for Nod2 mutations in CD.

The intestinal tract of mammals is colonized by a large number of microorganisms including trillions of bacteria that are referred to collectively as the gut microbiota. These indigenous microorganisms have co-evolved with the host in a symbiotic relationship. In addition to metabolic benefits, symbiotic bacteria provide the host with several functions that promote immune homeostasis, immune responses, and protection against pathogen colonization. The ability of symbiotic bacteria to inhibit pathogen colonization is mediated via several mechanisms including direct killing, competition for limited nutrients, and enhancement of immune responses. Pathogens have evolved strategies to promote their replication in the presence of the gut microbiota. Perturbation of the gut microbiota structure by environmental and genetic factors increases the risk of pathogen infection, promotes the overgrowth of harmful pathobionts, and the development of inflammatory disease. Understanding the interaction of the microbiota with pathogens and the immune system will provide critical insight into the pathogenesis of disease and the development of strategies to prevent and treat inflammatory disease.

Multiple myeloma is an incurable malignancy of plasma cells, and its pathogenesis is poorly understood. Here we report the massively parallel sequencing of 38 tumour genomes and their comparison to matched normal DNAs. Several new and unexpected oncogenic mechanisms were suggested by the pattern of somatic mutation across the data set. These include the mutation of genes involved in protein translation (seen in nearly half of the patients), genes involved in histone methylation, and genes involved in blood coagulation. In addition, a broader than anticipated role of NF-κB signalling was indicated by mutations in 11 members of the NF-κB pathway. Of potential immediate clinical relevance, activating mutations of the kinase BRAF were observed in 4% of patients, suggesting the evaluation of BRAF inhibitors in multiple myeloma clinical trials. These results indicate that cancer genome sequencing of large collections of samples will yield new insights into cancer not anticipated by existing knowledge. Multiple myeloma, a malignancy of plasma cells, remains incurable and is poorly understood. Chapman et al. have used next-generation sequencing to compare 38 multiple myeloma genomes with those of normal cells from the same patients. The disease involves mutations of genes with roles in protein translation, histone methylation and blood coagulation. In terms of clinically relevant findings, unexpected activating mutations were found in the kinase BRAF, inhibitors of which have recently shown dramatic clinical activity. This suggests that BRAF inhibitors should be evaluated in patients with BRAF-mutated multiple myeloma. Multiple myeloma, a malignancy of plasma cells, remains incurable and is poorly understood. Using next-generation sequencing of several multiple myeloma genomes reveals that this disease involves mutations of genes involved in protein translation, histone methylation and blood coagulation. The study suggests that BRAF inhibitors should be evaluated in multiple myeloma clinical trials.

Although the concept that cancers arise from "stem cells" or "germ cells" was first proposed about 150 years ago, it is only recently that advances in stem cell biology have given new impetus to the "cancer stem cell hypothesis." Two important related concepts of this hypothesis are that (a) tumors originate in either tissue stem cells or their immediate progeny through dysregulation of the normally tightly regulated process of self-renewal. As a result of this, (b) tumors contain a cellular subcomponent that retains key stem cell properties. These properties include self-renewal, which drives tumorigenesis, and differentiation albeit aberrant that contributes to cellular heterogeneity. Recent experimental evidence in a variety of tumors has lent strong support to the cancer stem cell hypothesis that represents a paradigm shift in our understanding of carcinogenesis and tumor cell biology. This hypothesis has fundamental implications for cancer risk assessment, early detection, prognostication, and prevention. Furthermore, the current development of cancer therapeutics based on tumor regression may have produced agents that kill differentiated tumor cells while sparing the rare cancer stem cell population. The development of more effective cancer therapies may thus require targeting this important cell population.

BACKGROUND: Most women with breast cancer who undergo breast-conserving surgery receive whole-breast irradiation. We examined whether the addition of regional nodal irradiation to whole-breast irradiation improved outcomes. METHODS: We randomly assigned women with node-positive or high-risk node-negative breast cancer who were treated with breast-conserving surgery and adjuvant systemic therapy to undergo either whole-breast irradiation plus regional nodal irradiation (including internal mammary, supraclavicular, and axillary lymph nodes) (nodal-irradiation group) or whole-breast irradiation alone (control group). The primary outcome was overall survival. Secondary outcomes were disease-free survival, isolated locoregional disease-free survival, and distant disease-free survival. RESULTS: Between March 2000 and February 2007, a total of 1832 women were assigned to the nodal-irradiation group or the control group (916 women in each group). The median follow-up was 9.5 years. At the 10-year follow-up, there was no significant between-group difference in survival, with a rate of 82.8% in the nodal-irradiation group and 81.8% in the control group (hazard ratio, 0.91; 95% confidence interval [CI], 0.72 to 1.13; P=0.38). The rates of disease-free survival were 82.0% in the nodal-irradiation group and 77.0% in the control group (hazard ratio, 0.76; 95% CI, 0.61 to 0.94; P=0.01). Patients in the nodal-irradiation group had higher rates of grade 2 or greater acute pneumonitis (1.2% vs. 0.2%, P=0.01) and lymphedema (8.4% vs. 4.5%, P=0.001). CONCLUSIONS: Among women with node-positive or high-risk node-negative breast cancer, the addition of regional nodal irradiation to whole-breast irradiation did not improve overall survival but reduced the rate of breast-cancer recurrence. (Funded by the Canadian Cancer Society Research Institute and others; MA.20 ClinicalTrials.gov number, NCT00005957.).

PURPOSE: Metastatic breast cancer (MBC) is incurable; its treatment is palliative. We investigated whether the presence of circulating tumor cells (CTCs) predicts treatment efficacy, progression-free survival (PFS), and overall survival (OS) in patients with newly diagnosed MBC who were about to start first-line therapy. PATIENTS AND METHODS: One hundred seventy-seven patients with measurable MBC were enrolled onto a prospective study. Eighty-three of the 177 patients were entering first-line treatment, and these patients are the focus of this analysis. CTCs from 7.5 mL of whole blood drawn before treatment initiation (baseline) and monthly thereafter for up to 6 months were isolated and enumerated using immunomagnetics. RESULTS: The mean (+/- standard deviation) follow-up time was 11.1 +/- 4.4 months (median, 12.2 months). Forty-three patients (52%) had > or = five CTCs at baseline. The median PFS was 7.2 months (95% CI, 4.9 to 9.4 months), and the median OS was more than 18 months. Patients with > or = five CTCs at baseline and at first follow-up (4 weeks) had a worse prognosis than patients with less than five CTCs (baseline: median PFS, 4.9 v 9.5 months, respectively; log-rank, P = .0014; median OS, 14.2 v > 18 months, respectively; log-rank, P = .0048; first follow-up: median PFS, 2.1 v 8.9 months, respectively; log-rank, P = .0070; median OS, 11.1 v > 18 months, respectively; log-rank, P = .0029). CTCs before and after the initiation of therapy were strong, independent prognostic factors. CONCLUSION: Detection of CTCs before initiation of first-line therapy in patients with MBC is highly predictive of PFS and OS. This technology can aid in appropriate patient stratification and design of tailored treatments.

Abstract Cancer develops through a process of somatic evolution 1,2 . Sequencing data from a single biopsy represent a snapshot of this process that can reveal the timing of specific genomic aberrations and the changing influence of mutational processes 3 . Here, by whole-genome sequencing analysis of 2,658 cancers as part of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA) 4 , we reconstruct the life history and evolution of mutational processes and driver mutation sequences of 38 types of cancer. Early oncogenesis is characterized by mutations in a constrained set of driver genes, and specific copy number gains, such as trisomy 7 in glioblastoma and isochromosome 17q in medulloblastoma. The mutational spectrum changes significantly throughout tumour evolution in 40% of samples. A nearly fourfold diversification of driver genes and increased genomic instability are features of later stages. Copy number alterations often occur in mitotic crises, and lead to simultaneous gains of chromosomal segments. Timing analyses suggest that driver mutations often precede diagnosis by many years, if not decades. Together, these results determine the evolutionary trajectories of cancer, and highlight opportunities for early cancer detection.

Enhancer of zeste homolog 2 (EZH2) is a mammalian histone methyltransferase that contributes to the epigenetic silencing of target genes and regulates the survival and metastasis of cancer cells. EZH2 is overexpressed in aggressive solid tumors by mechanisms that remain unclear. Here we show that the expression and function of EZH2 in cancer cell lines are inhibited by microRNA-101 (miR-101). Analysis of human prostate tumors revealed that miR-101 expression decreases during cancer progression, paralleling an increase in EZH2 expression. One or both of the two genomic loci encoding miR-101 were somatically lost in 37.5% of clinically localized prostate cancer cells (6 of 16) and 66.7% of metastatic disease cells (22 of 33). We propose that the genomic loss of miR-101 in cancer leads to overexpression of EZH2 and concomitant dysregulation of epigenetic pathways, resulting in cancer progression.

Abstract A challenge in oncology is to rationally and effectively integrate immunotherapy with traditional modalities, including radiotherapy. Here, we demonstrate that radiotherapy induces tumor-cell ferroptosis. Ferroptosis agonists augment and ferroptosis antagonists limit radiotherapy efficacy in tumor models. Immunotherapy sensitizes tumors to radiotherapy by promoting tumor-cell ferroptosis. Mechanistically, IFNγ derived from immunotherapy-activated CD8+ T cells and radiotherapy-activated ATM independently, yet synergistically, suppresses SLC7A11, a unit of the glutamate–cystine antiporter xc−, resulting in reduced cystine uptake, enhanced tumor lipid oxidation and ferroptosis, and improved tumor control. Thus, ferroptosis is an unappreciated mechanism and focus for the development of effective combinatorial cancer therapy. Significance: This article describes ferroptosis as a previously unappreciated mechanism of action for radiotherapy. Further, it shows that ferroptosis is a novel point of synergy between immunotherapy and radiotherapy. Finally, it nominates SLC7A11, a critical regulator of ferroptosis, as a mechanistic determinant of synergy between radiotherapy and immunotherapy. This article is highlighted in the In This Issue feature, p. 1631

Although the concept that cancers originate from stem cells (SC) is becoming scientifically accepted, mechanisms by which SC contribute to tumor initiation and progression are largely unknown. For colorectal cancer (CRC), investigation of this problem has been hindered by a paucity of specific markers for identification and isolation of SC from normal and malignant colon. Accordingly, aldehyde dehydrogenase 1 (ALDH1) was investigated as a possible marker for identifying colonic SC and for tracking them during cancer progression. Immunostaining showed that ALDH1(+) cells are sparse and limited to the normal crypt bottom, where SCs reside. During progression from normal epithelium to mutant (APC) epithelium to adenoma, ALDH1(+) cells increased in number and became distributed farther up the crypt. CD133(+) and CD44(+) cells, which are more numerous and broadly distributed in normal crypts, showed similar changes during tumorigenesis. Flow cytometric isolation of cancer cells based on enzymatic activity of ALDH (Aldefluor assay) and implantation of these cells in nonobese diabetic-severe combined immunodeficient mice (a) generated xenograft tumors (Aldefluor(-) cells did not), (b) generated them after implanting as few as 25 cells, and (c) generated them dose dependently. Further isolation of cancer cells using a second marker (CD44(+) or CD133(+) serially) only modestly increased enrichment based on tumor-initiating ability. Thus, ALDH1 seems to be a specific marker for identifying, isolating, and tracking human colonic SC during CRC development. These findings also support our original hypothesis, derived previously from mathematical modeling of crypt dynamics, that progressive colonic SC overpopulation occurs during colon tumorigenesis and drives CRC development.