Cancer Discovery

Decoding the Genomic and Functional Landscape of Emerging Subtypes in Ovarian Cancer

Abstract Ovarian high-grade serous carcinoma (HGSC) is characterized by pervasive genomic instability and high inter- and intra-tumor heterogeneity. Approximately half of HGSC tumors harbor homologous recombination deficiency (HRD), rendering them vulnerable to PARP inhibitors and platinum-based chemotherapy. In contrast, patients lacking HRD (HR-proficient, HRP) generally respond poorly to current therapies. To overcome heterogeneity and identify relevant HGSC subtypes, we characterized the genomic landscape of 640 tumors from 243 patients using whole-genome sequencing. Our chromosomal instability signature–based analysis characterized the structural variation landscape and revealed five HGSC subtypes, validated in an independent dataset. Two HRD subtypes, associated with BRCA1- or BRCA2-driven alterations, demonstrated favorable treatment responses. Strikingly, three HRP subtypes emerged, marked by unique structural alterations and gene expression patterns, tumor microenvironment interactions, and different chemotherapy responses. Notably, organoid experiments showed subtype-specific sensitivity to CHK1 inhibition, suggesting prexasertib as a potential targeted treatment for most currently untreatable HRP patients. Significance: These findings demonstrate that HGSC tumors can be divided into functionally and clinically distinct subtypes, offering new insights into the underlying biology of HGSC and providing a foundation to develop tailored therapeutic strategies for HRP tumors, which currently lack effective options.

Molecular Characterization of Endometrial Carcinomas in Black and White Patients Reveals Disparate Drivers with Therapeutic Implications

Abstract Although the incidence of endometrial carcinoma (EC) is similar in Black and White women, racial disparities are stark, with the highest mortality rates observed among Black patients. Here, analysis of 1,882 prospectively sequenced ECs using a clinical FDA-authorized tumor–normal panel revealed a significantly higher prevalence of high-risk histologic and molecular EC subtypes in self-identified Black (n = 259) compared with White (n = 1,623) patients. Clinically actionable alterations, including high tumor mutational burden/microsatellite instability, which confer benefit from immunotherapy, were less frequent in ECs from Black than from White patients. Ultramutated POLE molecular subtype ECs associated with favorable outcomes were rare in Black patients. Results were confirmed by genetic ancestry analysis. CCNE1 gene amplification, which is associated with aggressive clinical behavior, was more prevalent in carcinosarcomas occurring in Black than in White patients. ECs from Black and White patients display important differences in their histologic types, molecular subtypes, driver genetic alterations, and therapeutic targets. Significance: Our comprehensive analysis of prospectively clinically sequenced ECs revealed significant differences in their histologic and molecular composition and in the presence of therapeutic targets in Black versus White patients. These findings emphasize the importance of incorporating diverse populations into molecular studies and clinical trials to address EC disparities. This article is featured in Selected Articles from This Issue, p. 2293

Bicyclic Peptide Makes Targeting EphA2 Possible

Abstract A tumor-penetrating bicyclic peptide that delivers a toxic payload may have finally unlocked the therapeutic potential of targeting EphA2. According to phase I trial data, BT5528 yielded clinical responses in three patients with ovarian and urothelial cancers—without any of the toxicity issues that have plagued other EphA2-directed therapeutic candidates.

AZD5305 More Tolerable than Earlier PARP Agents

Abstract Findings from the phase I/IIa trial of AZD5305, a next-generation, highly selective PARP1 inhibitor, indicate that the drug is better tolerated in patients with ovarian, HER2-negative breast, pancreatic, and prostate cancers with BRCA1/2, PALB2, and RAD51C mutations compared with first-generation PARP inhibitors. In addition, 25% of 40 evaluable patients had a partial response.

Tumor-Derived Lysophosphatidic Acid Blunts Protective Type I Interferon Responses in Ovarian Cancer

Abstract Lysophosphatidic acid (LPA) is a bioactive lipid enriched in the tumor microenvironment of immunosuppressive malignancies such as ovarian cancer. Although LPA enhances the tumorigenic attributes of cancer cells, the immunomodulatory activity of this phospholipid messenger remains largely unexplored. Here, we report that LPA operates as a negative regulator of type I interferon (IFN) responses in ovarian cancer. Ablation of the LPA-generating enzyme autotaxin (ATX) in ovarian cancer cells reprogrammed the tumor immune microenvironment, extended host survival, and improved the effects of therapies that elicit protective responses driven by type I IFN. Mechanistically, LPA sensing by dendritic cells triggered PGE2 biosynthesis that suppressed type I IFN signaling via autocrine EP4 engagement. Moreover, we identified an LPA-controlled, immune-derived gene signature associated with poor responses to combined PARP inhibition and PD-1 blockade in patients with ovarian cancer. Controlling LPA production or sensing in tumors may therefore be useful to improve cancer immunotherapies that rely on robust induction of type I IFN. Significance: This study uncovers that ATX–LPA is a central immunosuppressive pathway in the ovarian tumor microenvironment. Ablating this axis sensitizes ovarian cancer hosts to various immunotherapies by unleashing protective type I IFN responses. Understanding the immunoregulatory programs induced by LPA could lead to new biomarkers predicting resistance to immunotherapy in patients with cancer. See related commentary by Conejo-Garcia and Curiel, p. 1841. This article is highlighted in the In This Issue feature, p. 1825

Navicixizumab plus Paclitaxel Shows Clinical Benefit in Platinum-Resistant Ovarian Cancer

Abstract Combined navicixizumab and paclitaxel showed durable activity in patients with platinum-resistant ovarian cancer.

Tissue-Resident Memory-like Lymphocytes Demonstrate Effector Activity in Ovarian Cancer

Abstract Tumor antigen recognition is limited to a small percentage of CD8+ T cells in ovarian cancer.

Rare Ovarian Cancer's First Positive Trial

Abstract The MEK1/2 inhibitor trametinib increases progression-free survival from 7.2 months to 13 months in women with recurrent low-grade serous ovarian cancer. The drug also boosts the overall response rate from 6% to 26%.

Strong HPV Vaccine Response Predicts Better Survival with Chemotherapy

Abstract Patients with HPV16+ cervical cancer and high T-cell responses to an HPV16 vaccine survived longer.

Tumor Immunity and Immunotherapy for HPV-Related Cancers

Abstract Human papillomavirus (HPV) infection drives tumorigenesis in the majority of cervical, oropharyngeal, anal, and vulvar cancers. Genetic and epidemiologic evidence has highlighted the role of immunosuppression in the oncogenesis of HPV-related malignancies. Here we review how HPV modulates the immune microenvironment and subsequent therapeutic implications. We describe the landscape of immunotherapies for these cancers with a focus on findings from early-phase studies exploring antigen-specific treatments, and discuss future directions. Although responses across these studies have been modest to date, a deeper understanding of HPV-related tumor biology and immunology may prove instrumental for the development of more efficacious immunotherapeutic approaches. Significance: HPV modulates the microenvironment to create a protumorigenic state of immune suppression and evasion. Our understanding of these mechanisms has led to the development of immunomodulatory treatments that have shown early clinical promise in patients with HPV-related malignancies. This review summarizes our current understanding of the interactions of HPV and its microenvironment and provides insight into the progress and challenges of developing immunotherapies for HPV-related malignancies.

Before They Were Malignant

Summary: A lack of understanding of how ovarian cancer originates in fallopian tube cells has hindered early detection and prevention, often resulting in diagnosis at advanced stages when treatment options are limited. In this issue of Cancer Discovery, two studies uncover critical microenvironmental changes that drive tumor initiation and progression, offering potential targets for earlier intervention. See related article by Kader et al., p. 1180 See related article by Garcia et al., p. 1203

Ironing Out the Kinks: Arming Natural Killer Cells against Ovarian Cancer

Summary:Ameliorating the tumor immune microenvironment is a key strategy to improve the therapeutic outcomes of patients with cancer. Sandoval and colleagues demonstrate that iron chelation enhances type I IFN production, promotes NK cell tumor trafficking and activation, and synergizes with chemotherapy drug cisplatin to reduce metastatic ovarian cancer progression in murine models.See related article by Sandoval et al., p. 1901

Thirty Years of BRCA1: Mechanistic Insights and Their Impact on Mutation Carriers

Abstract Thirty years ago, the cloning of the first breast cancer susceptibility gene, BRCA1, marked a milestone in our understanding of hereditary breast and ovarian cancers. This discovery initiated extensive research into DNA repair mechanisms, BRCA1-associated tumorigenesis, and therapeutic interventions. Despite these advances, critical questions remain unanswered, such as the evolution of BRCA1-associated tumors and their tissue specificity. These issues hinder the development of effective treatment and prevention strategies, which ultimately aim to improve the quality of life for BRCA1 mutation carriers. In this review, we discuss current knowledge, identify existing gaps, and suggest possible avenues to tackle these challenges. Significance: Here, we explore the impact of three decades of BRCA1 research on the lives of mutation carriers and propose strategies to improve the prevention and treatment of BRCA1-associated cancer.

Early Detection of Ovarian Cancer Using Cell-Free DNA Fragmentomes and Protein Biomarkers

Abstract Ovarian cancer is a leading cause of death for women worldwide, in part due to ineffective screening methods. In this study, we used whole-genome cell-free DNA (cfDNA) fragmentome and protein biomarker [cancer antigen 125 (CA-125) and human epididymis protein 4 (HE4)] analyses to evaluate 591 women with ovarian cancer, with benign adnexal masses, or without ovarian lesions. Using a machine learning model with the combined features, we detected ovarian cancer with specificity >99% and sensitivities of 72%, 69%, 87%, and 100% for stages I to IV, respectively. At the same specificity, CA-125 alone detected 34%, 62%, 63%, and 100%, and HE4 alone detected 28%, 27%, 67%, and 100% of ovarian cancers for stages I to IV, respectively. Our approach differentiated benign masses from ovarian cancers with high accuracy (AUC = 0.88, 95% confidence interval, 0.83–0.92). These results were validated in an independent population. These findings show that integrated cfDNA fragmentome and protein analyses detect ovarian cancers with high performance, enabling a new accessible approach for noninvasive ovarian cancer screening and diagnostic evaluation. Significance: There is an unmet need for effective ovarian cancer screening and diagnostic approaches that enable earlier-stage cancer detection and increased overall survival. We have developed a high-performing accessible approach that evaluates cfDNA fragmentomes and protein biomarkers to detect ovarian cancer.

AMG 193 Effective in Multiple Tumor Types

Abstract In a phase I trial of the MTA-cooperative PRMT5 inhibitor AMG 193, five of 39 patients with advanced MTAP-deleted solid tumors who had scans following initial treatment experienced partial responses. The responses occurred in five tumor types—esophageal, pancreatic, renal cell, gallbladder, and ovarian Sertoli-Leydig cell cancer.

Blocking Netrin-1 Slows Cancer Progression

Abstract Preclinical and early clinical data demonstrate that treating endometrial cancer with the netrin-1 inhibitor NP137 helps arrest the epithelial-to-mesenchymal transition and disease progression. Additional research is needed to understand the mechanism of action between the monoclonal antibody and chemotherapy, as well as determine whether this treatment could help patients with other cancers.

Selinexor Delays Wild-type TP53 Endometrial Cancer Progression

Abstract In a phase III trial, taking the XPO1 inhibitor selinexor as maintenance therapy was associated with a significant and durable progression-free survival benefit for women with advanced or recurrent TP53 wild-type endometrial cancer—regardless of microsatellite stability.

ICI–Chemo New Standard for Endometrial Cancer

Abstract The phase III RUBY and NRG-GY018 trials indicate that women with advanced endometrial cancer whose disease is newly diagnosed or has recurred for the first time benefit from the combination of a PD-1 inhibitor with standard chemotherapy. Adding either dostarlimab or pembrolizumab significantly prolonged progression-free survival, with overall survival also trending in the right direction.

Distinct Mechanisms of Mismatch-Repair Deficiency Delineate Two Modes of Response to Anti–PD-1 Immunotherapy in Endometrial Carcinoma

Abstract Mismatch repair–deficient (MMRd) cancers have varied responses to immune-checkpoint blockade (ICB). We conducted a phase II clinical trial of the PD-1 inhibitor pembrolizumab in 24 patients with MMRd endometrial cancer (NCT02899793). Patients with mutational MMRd tumors (6 patients) had higher response rates and longer survival than those with epigenetic MMRd tumors (18 patients). Mutation burden was higher in tumors with mutational MMRd compared with epigenetic MMRd; however, within each category of MMRd, mutation burden was not correlated with ICB response. Pretreatment JAK1 mutations were not associated with primary resistance to pembrolizumab. Longitudinal single-cell RNA-seq of circulating immune cells revealed contrasting modes of antitumor immunity for mutational versus epigenetic MMRd cancers. Whereas effector CD8+ T cells correlated with regression of mutational MMRd tumors, activated CD16+ NK cells were associated with ICB-responsive epigenetic MMRd tumors. These data highlight the interplay between tumor-intrinsic and tumor-extrinsic factors that influence ICB response. Significance: The molecular mechanism of MMRd is associated with response to anti–PD-1 immunotherapy in endometrial carcinoma. Tumors with epigenetic MMRd or mutational MMRd are correlated with NK cell or CD8+ T cell–driven immunity, respectively. Classifying tumors by the mechanism of MMRd may inform clinical decision-making regarding cancer immunotherapy. This article is highlighted in the In This Issue feature, p. 247

Combination Vistusertib and Anastrozole Shows Benefit in Endometrial Cancer

Abstract The primary endpoint of 8-week progression-free rate was met with this combination.

Genetically Defined, Syngeneic Organoid Platform for Developing Combination Therapies for Ovarian Cancer

Abstract The paucity of genetically informed, immunocompetent tumor models impedes evaluation of conventional, targeted, and immune therapies. By engineering mouse fallopian tube epithelial organoids using lentiviral gene transduction and/or CRISPR/Cas9 mutagenesis, we generated multiple high-grade serous tubo-ovarian cancer (HGSC) models exhibiting mutational combinations seen in patients with HGSC. Detailed analysis of homologous recombination (HR)–proficient (Trp53−/−;Ccne1OE;Akt2OE;KrasOE), HR-deficient (Trp53−/−;Brca1−/−;MycOE), and unclassified (Trp53−/−;Pten−/−;Nf1−/−) organoids revealed differences in in vitro properties (proliferation, differentiation, and “secretome”), copy-number aberrations, and tumorigenicity. Tumorigenic organoids had variable sensitivity to HGSC chemotherapeutics, and evoked distinct immune microenvironments that could be modulated by neutralizing organoid-produced chemokines/cytokines. These findings enabled development of a chemotherapy/immunotherapy regimen that yielded durable, T cell–dependent responses in Trp53−/−;Ccne1OE;Akt2OE;Kras HGSC; in contrast, Trp53−/−;Pten−/−;Nf1−/− tumors failed to respond. Mouse and human HGSC models showed genotype-dependent similarities in chemosensitivity, secretome, and immune microenvironment. Genotype-informed, syngeneic organoid models could provide a platform for the rapid evaluation of tumor biology and therapeutics. Significance: The lack of genetically informed, diverse, immunocompetent models poses a major barrier to therapeutic development for many malignancies. Using engineered fallopian tube organoids to study the cell-autonomous and cell-nonautonomous effects of specific combinations of mutations found in HGSC, we suggest an effective combination treatment for the currently intractable CCNE1-amplified subgroup. This article is highlighted in the In This Issue feature, p. 211

Molecular and Immune Correlates of Response to First-Line De-escalated Chemotherapy plus Penpulimab and Anlotinib in Advanced Cervical Cancer

Abstract The standard of care for advanced cervical cancer includes chemotherapy, antiangiogenic, and/or immune checkpoint blockade regimens. Although effective, it leads to pleiotropic side effects. Deescalation chemotherapy together with immunotargeted therapies has been proven effective and less toxic in other cancers. In this study, we conducted a multicenter, single-arm, phase II study of first-line deescalated platinum-based chemotherapy plus anlotinib and penpulimab, followed by maintenance therapy solely with anlotinib and penpulimab in patients with PD-L1–positive, persistent, recurrent, or metastatic cervical cancer. Of 32 efficacy-evaluable patients, 30 (93.8%, 95% confidence interval, 79.2%–99.2%) had an investigator-confirmed objective response. Single-nucleus RNA sequencing implied enhanced chemotaxis and proliferative activity of tumor-infiltrating T cells, and activated germinal center B cells portended optimal treatment response. Patients with a high tertiary lymphoid structure-to-tumor area ratio exhibited better survival. Our findings lay the groundwork for the feasibility of first-line de-escalated chemotherapy plus anlotinib and penpulimab in patients with metastatic, persistent, or recurrent cervical cancer. Significance: We recruited 34 patients with advanced cervical cancer receiving two cycles of platinum-based chemotherapy plus anlotinib and penpulimab, followed by maintenance therapy solely with anlotinib and penpulimab, and showed safety and efficacy of this deescalation regimen. This work highlights the potential for personalized treatment strategies and feasibility of reduced-toxicity regimens.

Iron Chelation Therapy Elicits Innate Immune Control of Metastatic Ovarian Cancer

Abstract Iron accumulation in tumors contributes to disease progression and chemoresistance. Although targeting this process can influence various hallmarks of cancer, the immunomodulatory effects of iron chelation in the tumor microenvironment are unknown. Here, we report that treatment with deferiprone, an FDA-approved iron chelator, unleashes innate immune responses that restrain ovarian cancer. Deferiprone reprogrammed ovarian cancer cells toward an immunostimulatory state characterized by the production of type-I IFN and overexpression of molecules that activate NK cells. Mechanistically, these effects were driven by innate sensing of mitochondrial DNA in the cytosol and concomitant activation of nuclear DNA damage responses triggered upon iron chelation. Deferiprone synergized with chemotherapy and prolonged the survival of mice with ovarian cancer by bolstering type-I IFN responses that drove NK cell-dependent control of metastatic disease. Hence, iron chelation may represent an alternative immunotherapeutic strategy for malignancies that are refractory to current T-cell–centric modalities. Significance: This study uncovers that targeting dysregulated iron accumulation in ovarian tumors represents a major therapeutic opportunity. Iron chelation therapy using an FDA-approved agent causes immunogenic stress responses in ovarian cancer cells that delay metastatic disease progression and enhance the effects of first-line chemotherapy. See related commentary by Bell and Zou, p. 1771

A New Paradigm of the Origins of Circulating DNA in Patients with Cancer

Summary: By shedding light on the cellular origins of circulating DNA (cirDNA), this research provides important insights into the mechanisms of cirDNA production in cancer. Contrary to expectations, the increased cirDNA in patients with cancer was not derived predominantly from neoplastic cells or surrounding nonneoplastic epithelial cells; rather, the excess cirDNA originated primarily from leukocytes, implying a systemic impact of cancer on cell turnover or DNA clearance. See related article by Mattox et al., p. 2166 (1).

The Origin of Highly Elevated Cell-Free DNA in Healthy Individuals and Patients with Pancreatic, Colorectal, Lung, or Ovarian Cancer

Abstract Cell-free DNA (cfDNA) concentrations from patients with cancer are often elevated compared with those of healthy controls, but the sources of this extra cfDNA have never been determined. To address this issue, we assessed cfDNA methylation patterns in 178 patients with cancers of the colon, pancreas, lung, or ovary and 64 patients without cancer. Eighty-three of these individuals had cfDNA concentrations much greater than those generally observed in healthy subjects. The major contributor of cfDNA in all samples was leukocytes, accounting for ∼76% of cfDNA, with neutrophils predominating. This was true regardless of whether the samples were derived from patients with cancer or the total plasma cfDNA concentration. High levels of cfDNA observed in patients with cancer did not come from either neoplastic cells or surrounding normal epithelial cells from the tumor's tissue of origin. These data suggest that cancers may have a systemic effect on cell turnover or DNA clearance. Significance: The origin of excess cfDNA in patients with cancer is unknown. Using cfDNA methylation patterns, we determined that neither the tumor nor the surrounding normal tissue contributes this excess cfDNA—rather it comes from leukocytes. This finding suggests that cancers have a systemic impact on cell turnover or DNA clearance. See related commentary by Thierry and Pisareva, p. 2122. This article is featured in Selected Articles from This Issue, p. 2109

Ultrasensitive Detection of Circulating LINE-1 ORF1p as a Specific Multicancer Biomarker

Abstract Improved biomarkers are needed for early cancer detection, risk stratification, treatment selection, and monitoring treatment response. Although proteins can be useful blood-based biomarkers, many have limited sensitivity or specificity for these applications. Long INterspersed Element-1 (LINE-1) open reading frame 1 protein (ORF1p) is a transposable element protein overexpressed in carcinomas and high-risk precursors during carcinogenesis with negligible expression in normal tissues, suggesting ORF1p could be a highly specific cancer biomarker. To explore ORF1p as a blood-based biomarker, we engineered ultrasensitive digital immunoassays that detect mid-attomolar (10−17 mol/L) ORF1p concentrations in plasma across multiple cancers with high specificity. Plasma ORF1p shows promise for early detection of ovarian cancer, improves diagnostic performance in a multianalyte panel, provides early therapeutic response monitoring in gastroesophageal cancers, and is prognostic for overall survival in gastroesophageal and colorectal cancers. Together, these observations nominate ORF1p as a multicancer biomarker with potential utility for disease detection and monitoring. Significance: The LINE-1 ORF1p transposon protein is pervasively expressed in many cancers and is a highly specific biomarker of multiple common, lethal carcinomas and their high-risk precursors in tissue and blood. Ultrasensitive ORF1p assays from as little as 25 μL plasma are novel, rapid, cost-effective tools in cancer detection and monitoring. See related commentary by Doucet and Cristofari, p. 2502. This article is featured in Selected Articles from This Issue, p. 2489

Cancer Mutations Converge on a Collection of Protein Assemblies to Predict Resistance to Replication Stress

Abstract Rapid proliferation is a hallmark of cancer associated with sensitivity to therapeutics that cause DNA replication stress (RS). Many tumors exhibit drug resistance, however, via molecular pathways that are incompletely understood. Here, we develop an ensemble of predictive models that elucidate how cancer mutations impact the response to common RS-inducing (RSi) agents. The models implement recent advances in deep learning to facilitate multidrug prediction and mechanistic interpretation. Initial studies in tumor cells identify 41 molecular assemblies that integrate alterations in hundreds of genes for accurate drug response prediction. These cover roles in transcription, repair, cell-cycle checkpoints, and growth signaling, of which 30 are shown by loss-of-function genetic screens to regulate drug sensitivity or replication restart. The model translates to cisplatin-treated cervical cancer patients, highlighting an RTK–JAK–STAT assembly governing resistance. This study defines a compendium of mechanisms by which mutations affect therapeutic responses, with implications for precision medicine. Significance: Zhao and colleagues use recent advances in machine learning to study the effects of tumor mutations on the response to common therapeutics that cause RS. The resulting predictive models integrate numerous genetic alterations distributed across a constellation of molecular assemblies, facilitating a quantitative and interpretable assessment of drug response. This article is featured in Selected Articles from This Issue, p. 384

HPV16-Expressing Tumors Release Multiple IL1 Ligands to Orchestrate Systemic Immunosuppression Whose Disruption Enables Efficacy of a Therapeutic Vaccine

Abstract It is well-established that symptomatic cancers evade immune destruction by coalescing tumor microenvironments to suppress adaptive immunity. Additionally, mouse models of cervical and other cancers have revealed a capability of tumors to systemically induce the expansion of neutrophils that cripple T-cell development in spleen and lymph nodes, further impairing immune responses. Now we show that human papillomavirus type 16 (HPV16)–driven squamous cell tumors in the cervix and skin release into the circulatory system four immunoregulatory ligands – IL-1α, IL-1β, IL-33, and IL-36β – that bias the bone marrow toward granulocytic myelopoiesis, producing immunosuppressive neutrophils populating spleens and tumors. An IL-1 family coreceptor antagonist, anti-IL1RAP, abrogates this neutrophil expansion and complements an otherwise inefficacious HPV16 E7 peptide vaccine to elicit an effective antitumor immune response that is further sustained by anti–CTLA-4. Evidence for similarly IL-1–driven systemic immunosuppression in human cervical tumors encourages evaluation of this combinatorial therapeutic strategy for treating a largely immunoevasive cancer type. Significance: Cervical cancer is the fourth leading cause of cancer deaths in women worldwide. Although the disease is driven by two antigenic viral oncoproteins, therapeutic vaccines have proved ineffective, inferentially due to systemic immunosuppression. This study elucidated an actionable mechanism, whose disruption renders an oncoprotein vaccine efficacious, with translational potential.

Aged and BRCA -Mutated Stromal Cells Drive Epithelial Cell Transformation

Abstract The fundamental steps in high-grade serous ovarian cancer (HGSOC) initiation are unclear, presenting critical barriers to the prevention and early detection of this deadly disease. Current models propose that fallopian tube epithelial (FTE) cells transform into serous tubal intraepithelial carcinoma (STIC) precursor lesions and subsequently into HGSOC. In this study, we report that an epigenetically altered mesenchymal stem cell niche, termed high-risk mesenchymal stromal/stem cell (hrMSC), exists prior to STIC lesion formation. hrMSCs are enriched in STIC stroma and contribute to a stromal “field effect” extending beyond the borders of the STIC lesion. hrMSCs promote DNA damage in FTE cells while also fostering FTE cell survival. hrMSCs induce malignant transformation of the FTE, resulting in metastatic cancer in vivo, indicating that hrMSCs promote cancer initiation. hrMSCs are significantly enriched in BRCA1/2 mutation carriers and increase with age. Combined, these findings indicate that hrMSCs can incite ovarian cancer initiation and have important implications for ovarian cancer detection and prevention. Significance: This work demonstrates a critical role of fallopian tube stromal cells in HGSOC initiation with implications for the pathophysiology of HGSOC formation and the development of prevention and early detection strategies critically needed in this disease. Additionally, the identification of stromal-mediated epithelial transformation has broad implications for understanding pan-cancer initiation. See related commentary by Recouvreux and Orsulic, p. 1093

Multimodal Spatial Profiling Reveals Immune Suppression and Microenvironment Remodeling in Fallopian Tube Precursors to High-Grade Serous Ovarian Carcinoma

Abstract High-grade serous ovarian cancer (HGSOC) originates from fallopian tube (FT) precursors. However, the molecular changes that occur as precancerous lesions progress to HGSOC are not well understood. To address this, we integrated high-plex imaging and spatial transcriptomics to analyze human tissue samples at different stages of HGSOC development, including p53 signatures, serous tubal intraepithelial carcinomas (STIC), and invasive HGSOC. Our findings reveal immune modulating mechanisms within precursor epithelium, characterized by chromosomal instability, persistent IFN signaling, and dysregulated innate and adaptive immunity. FT precursors display elevated expression of MHC class I, including HLA-E, and IFN-stimulated genes, typically linked to later-stage tumorigenesis. These molecular alterations coincide with progressive shifts in the tumor microenvironment, transitioning from immune surveillance in early STICs to immune suppression in advanced STICs and cancer. These insights identify potential biomarkers and therapeutic targets for HGSOC interception and clarify the molecular transitions from precancer to cancer. Significance: This study maps the immune response in FT precursors of HGSOC, highlighting localized IFN signaling, chromosomal instability, and competing immune surveillance and suppression along the progression axis. It provides an explorable public spatial profiling atlas for investigating precancer mechanisms, biomarkers, and early detection and interception strategies. See related commentary by Recouvreux and Orsulic, p. 1093

Simple Hysterectomy Safe for Some Cervical Cancers

Abstract Findings from the SHAPE trial confirm that carefully selected women with early-stage cervical cancer can undergo a simple hysterectomy instead of a radical procedure without increasing their risk of disease recurrence. The findings are likely to set a new global standard of care for patients with low-risk disease and help to improve outcomes in developing countries, where deaths from cervical cancer are highest.

Low-Dose Radiotherapy Reverses Tumor Immune Desertification and Resistance to Immunotherapy

Abstract Developing strategies to inflame tumors is critical for increasing response to immunotherapy. Here, we report that low-dose radiotherapy (LDRT) of murine tumors promotes T-cell infiltration and enables responsiveness to combinatorial immunotherapy in an IFN-dependent manner. Treatment efficacy relied upon mobilizing both adaptive and innate immunity and depended on both cytotoxic CD4+ and CD8+ T cells. LDRT elicited predominantly CD4+ cells with features of exhausted effector cytotoxic cells, with a subset expressing NKG2D and exhibiting proliferative capacity, as well as a unique subset of activated dendritic cells expressing the NKG2D ligand RAE1. We translated these findings to a phase I clinical trial administering LDRT, low-dose cyclophosphamide, and immune checkpoint blockade to patients with immune-desert tumors. In responsive patients, the combinatorial treatment triggered T-cell infiltration, predominantly of CD4+ cells with Th1 signatures. Our data support the rational combination of LDRT with immunotherapy for effectively treating low T cell–infiltrated tumors. Significance: Low-dose radiation reprogrammed the tumor microenvironment of tumors with scarce immune infiltration and together with immunotherapy induced simultaneous mobilization of innate and adaptive immunity, predominantly CD4+ effector T cells, to achieve tumor control dependent on NKG2D. The combination induced important responses in patients with metastatic immune-cold tumors. This article is highlighted in the In This Issue feature, p. 1

Belly Fat Weakens Immune Fitness

Summary: Much work has been done to reduce cancer immunosuppression through inhibiting soluble proteins, surface molecules, and suppressive cells. This article shows an important role for the lipid lysophosphatidic acid, whose suppression shows promise as a novel cancer immunotherapeutic, demonstrated in ovarian cancer. See related article by Chae et al., 1904 (5).