Pan-cancer analysis of genomic scar signatures associated with homologous recombination deficiency suggests novel indications for existing cancer drugs

Homologous recombination deficiency among patients with germline or somatic non-BRCA1/2 homologous recombination repair gene variations

This study examined the relationship between homologous recombination deficiency (HRD) and variations in non-BRCA1/2 homologous recombination repair (HRR) genes. 27.3% (132/483) of the patients with ovarian, breast, endometrial, prostate, and pancreatic cancers carrying non-BRCA1/2 HRR variations were HRD + . Germline mutations were associated with significantly higher HRD+ rates than somatic mutations, while biallelic alterations did not show stronger associations with HRD compared to monoallelic alterations. High HRD+ rates (66.7-100.0%) were associated with variations in PALB2, RAD51C/D, and RAD54L, while low HRD+ rates (0-37.5%) corresponded with variations in PTEN, ATM, BRIP1, CDK12, and NBN, which may be influenced by variation grade and tissue origin. HRD positivity was mutually exclusive with HER2+ status in breast cancer and with TMB-H/MSI-H in endometrial cancer. Overall, these findings highlight the different strengths of the correlation between non-BRCA1/2 HRR gene variations and HRD and guide HRD testing in cases of "BRCA1/2-wildtype" results.

Synergistic suppression of cholangiocarcinoma cells via DNA damage response and cell cycle arrest by dual targeting PARP and ATM in DNA damage repair pathway

This study investigated alterations in DNA damage repair (DDR) genes in cholangiocarcinoma (CCA) influencing cellular vulnerability to DDR inhibitors, notably poly (ADP-ribose) polymerase inhibitors (PARPi) and ataxia-telangiectasia mutated inhibitors (ATMi). Genomic DDR alterations in CCA tumors were identified via cBioPortal. The cytotoxic effect of the inhibitors was determined in 8 CCA cell lines. Cell cycle arrest and apoptosis were determined using flow cytometry. The levels of γ-H2A histone family member X (γ-H2AX) were evaluated using an immunofluorescence assay. Proteins associated with the cell cycle and DDR were evaluated using Western blotting. Among these CCA cells, BRCA-mutated KKU-023 cells exhibited the highest PARPi sensitivity. Co-treatment with ATMi induced a synthetic homologous recombination deficiency (HRD) state in BRCA-proficient CCA cells, thereby sensitizing them to PARPi. This drug combination suppressed CCA cell growth via G2/M phase arrest, downregulated cyclin A and B1 expression, and enhanced apoptosis. Mechanistically, this synergistic cytotoxicity was attributed to increased DNA double-strand breaks, evidenced by elevated γ-H2AX and reduced RAD51 expression, signifying compromised DNA repair. These preclinical findings support the therapeutic potential of DDR inhibitors, individually or in combination, for CCA subsets characterized by DDR gene alterations.

HR eye & MMR eye: one-day assessment of DNA repair-defective tumors eligible for targeted therapy

Homologous recombination (HR) and mismatch repair (MMR) act as guardians of the human genome, and defects in HR or MMR are causative in at least a quarter of all malignant tumors. Although these DNA repair-deficient tumors are eligible for effective targeted therapies, fully reliable diagnostic strategies based on functional assay have yet to be established, potentially limiting safe and proper application of the molecular targeted drugs. Here we show that transient transfection of artificial DNA substrates enables ultrarapid detection of HR and MMR. This finding led us to develop a diagnostic strategy that can determine the cellular HR/MMR status within one day without the need for control cells or tissues. Notably, the accuracy of this method allowed the discovery of a pathogenic RAD51D mutation, which was missed by existing companion diagnostic tests. Our methods, termed HR eye and MMR eye, are applicable to frozen tumor tissues and roughly predict the response to therapy. Overall, the findings presented here could pave the way for accurately assessing malignant tumors with functional defects in HR or MMR, a step forward in accelerating precision medicine.

Clinical Characteristics and Survival of Ovarian Cancer Patients According to Homologous Recombination Deficiency Status

BACKGROUND

HRD is a key biomarker in ovarian cancer, predicting response to PARP inhibitors. However, it remains unclear whether HRD-positive patients differ from HRD-negative patients in terms of clinical characteristics in PARP inhibitor-naïve populations. This study aims to evaluate platinum-sensitive PARP-inhibitor naïve ovarian cancer patients' clinical characteristics and survival outcomes based on HRD status. Secondly, to investigate whether platinum-resistant patients with homologous recombination repair (HRR) gene mutations are HRD-positive.

METHODS

Two distinct HRD algorithms-an in-house genomic instability score (GIS) and the normalized large-scale state transitions score (nLST)-were used to stratify patients as HRD-positive or HRD-negative. Clinical data and survival in PARP inhibitor-naïve, platinum-sensitive HGSC patients were analyzed.

RESULTS

A total of 71 platinum-sensitive PARP-inhibitor naïve patients were analyzed. By in-house GIS, 37 patients (52%) were classified as HRD-positive and 34 (48%) as HRD-negative. Using nLST, 43 (61%) were HRD-positive and 28 (39%) were HRD-negative. Our analysis revealed no significant differences in clinical parameters or survival between HRD-positive and HRD-negative platinum-sensitive patients. The only observed difference was that somatic BRCA1/2-mutated patients were younger. In the subgroup of six platinum-resistant patients harboring HRR gene mutations, four patients (67%) were classified as HRD positive.

CONCLUSIONS

Our findings suggest that HRD status does not significantly influence clinical characteristics or survival outcomes in platinum-sensitive, PARP inhibitor-naïve HGSC patients. As some platinum-resistant patients with HRR gene mutations were HRD positive; this subgroup may benefit from further investigation into the potential effect of PARP inhibitors.

PARP Inhibitors in the Neoadjuvant Setting; A Comprehensive Overview of the Rationale for their Use, Past and Ongoing Clinical Trials

PURPOSEOF REVIEW

Poly (ADP-ribose) polymerases (PARPs) are enzymes essential for detecting and repairing DNA damage through poly-ADP-ribosylation. In cancer, cells with deficiencies in homologous recombination repair mechanisms often become more dependent on PARP-mediated repair mechanisms to effectively repair dsDNA breaks. As such, PARP inhibitors (PARPis) were introduced into clinical practice, serving as a key targeted therapy option through synthetic lethality in the treatment of cancers with homologous recombination repair deficiency (HRD). Though PARPis are currently approved in the adjuvant setting for several cancer types such as ovarian, breast, prostate and pancreatic cancer, their potential role in the neoadjuvant setting remains under investigation. This review outlines the rationale for using PARPi in the neoadjuvant setting and evaluates findings from early and ongoing clinical trials.

RECENT FINDINGS

Our analysis indicates that numerous studies have explored PARPi as a neoadjuvant treatment for HRD-related cancers. The majority of neoadjuvant PARPi trials have been performed in breast and ovarian cancer, while phase II/III evidence supporting efficacy in prostate and pancreatic cancers remains limited. Studies are investigating PARPi in the neoadjuvant setting of HRD-related cancers. Future research should prioritize combination strategies with immune checkpoint inhibitors and expand outcome measures to include patient satisfaction and quality-of-life metrics.

Identifying Rare Germline Variants Associated with Metastatic Prostate Cancer Through an Extreme Phenotype Study

Background

Studies of germline variants in prostate cancer (PCa) have largely focused on their connections to cancer predisposition. However, an understanding of how heritable factors contribute to cancer progression and metastasis remain limited.

Objective

To identify low frequency to rare germline nonsynonymous variants associated with increased risk for metastatic PCa (mPCa), while providing functional validation.

Design

We assembled an extreme phenotype cohort (EPC) of 52 patients diagnosed with predominantly high-grade (Gleason Score (GS) ≥ 8) PCa and > 7 years of follow-up for which localized treatment naïve tumor tissues were available. In half of the cases, the tumor had metastasized to bone, providing an even distribution of bone mPCa and non mPCa cases. Tumor and matched distant benign DNA samples were exome sequenced and analyzed for germline variants with population-wide minor allelic frequencies ≤ 2%. Findings were validated using two independent PCa germline cohorts, including a closely matched Australian study biased to aggressive disease (n = 53) and Pan Prostate Cancer Group (PPCG, n = 976). Two mPCa-promoting candidate variants in KDM6B and BRCA2 were engineered into cell lines and functionalized.

Results

Germline nonsynonymous rare variants (gnsRVs) identified in 25 DNA Damage Repair (DDR) genes were significantly enriched in the mPCa patients (p=4.57e-06). Conversely, the prevalence of synonymous variants at minor allele frequencies of ≤ 2% were similar between the mPCa and non mPCa patients. The predictive power of variants in 53 non-DDR genes was validated in the Australian cohort (p=0.028) and correlated with high-risk PCa in PPCG (p=0.03). KDM6B K973Q showed functional significance despite being annotated as benign in ClinVar, while BRCA2 I1962T showed sensitivity to Olaparib. In total, six EPC variants related to DNA repair or epigenetics were found to alter enzymatic activity.

Conclusions

EPCs coupled with low frequency/rare variant analyses may advance understanding of interactions between the germline and tumor in PCa. We identified a series of germline variants that were enriched among mPCa patients. Moreover, we showed that one of these variants confers a metastatic phenotype. Our findings suggest that germline testing at diagnosis may improve treatment stratification in PCa.

Patient summary

The presence of specific genetic variants among men with PCa may elevate the risk of mPCa once PCa develops. Knowledge of the variant burden at time of diagnosis may enable accurate stratification of some patients for aggressive therapeutic interventions.

Mono-ubiquitination of TopBP1 by PHRF1 enhances ATR activation and genomic stability

The TopBP1-ATR axis is critical for maintaining genomic stability during DNA replication stress, yet the precise regulation of TopBP1 in replication stress responses remains poorly understood. In this study, we identified PHD and Ring Finger Domains 1 (PHRF1) as an important ATR activator through its interaction with TopBP1. Our analysis revealed a correlation between PHRF1 and genomic stability in cancer patients. Mechanistically, PHRF1 is recruited to DNA lesions in a manner dependent on its PHD domain and histone methylation. Subsequently, PHRF1 mono-ubiquitinates TopBP1 at lysine 73, which enhances the TopBP1-ATR interaction and activates ATR. Depletion of PHRF1 disrupts ATR activation and sensitizes cells to replication stress-inducing agents. Furthermore, conditional knockout of Phrf1 in mice leads to early lethality and impaired ATR-Chk1 axis signaling. Collectively, our findings establish PHRF1 as a novel E3 ligase for TopBP1, coordinating the replication stress response by enhancing TopBP1-ATR signaling.

An MGRN1-Based Biomarker Combination Accurately Predicts Melanoma Patient Survival

With ever-increasing incidence and high metastatic potential, cutaneous melanoma is the deadliest skin cancer. Risk prediction based on the Tumor-Node-Metastasis (TNM) staging system has medium accuracy with intermediate IIB-IIIB stages, as roughly 25% of patients with low-medium-grade TNM, and hence a favorable prognostic, undergo an aggressive disease with short survival and around 15% of deaths arise from metastases of thin, low-risk lesions. Therefore, reliable prognostic biomarkers are required. We used genomic and clinical information of melanoma patients from the TCGA-SKCM cohort and two GEO studies for discovery and validation of potential biomarkers, respectively. Neither mutation nor overexpression of major melanoma driver genes provided significant prognostic information. Conversely, expression of MGRN1 and the melanocyte-specific genes MLANA, PMEL, and TYRP1 provided a simple 4-gene signature identifying with high-sensitivity (>80%), low-medium TNM patients with adverse outcomes. Transcriptomic analysis of tumors with this signature, or from low-medium-grade TNM patients with poor outcomes, revealed comparable dysregulation of an inflammatory response, cell cycle progression, and DNA damage/repair programs. A functional analysis of MGRN1-knockout cells confirmed these molecular features. Therefore, the simple MGRN1-MLANA-PMEL-TYRP1 combination of biomarkers complemented TNM staging prognostic accuracy and pointed to the dysregulation of immunological responses and genomic stability as determinants of a melanoma outcome.

Homologous recombination repair status in metastatic prostate cancer by next-generation sequencing and functional immunofluorescence

Metastatic prostate cancer (mPC) is enriched for homologous recombination repair (HRR) gene alterations, which have prognostic and predictive value. Routine clinical implementation of next-generation sequencing (NGS) is still limited. We investigated the association between genomic and functional loss of HRR, using NGS and RAD51 immunofluorescence (RAD51-IF) in 219 primary or metastatic biopsies from 187 patients with stage IV prostate cancer. NGS showed frequent genomic alterations in TP53 (40%), AR (15%), PTEN (14%), FOXA1 (12%), MYC (10%), BRCA2 (9%), ATM (8%), and BRCA1 (2%). We pursued RAD51-IF in 206 samples; of those, 139/206 (67%) were evaluable. 21% of samples had RAD51-low score compatible with HRR deficiency (HRD). RAD51-IF showed high sensitivity (71%) and specificity (86%) for BRCA1/2 alterations. Patients with RAD51-low scores experienced longer progression-free survival (PFS) on poly(ADP-ribose) polymerase inhibitors (PARPi) or platinum chemotherapy. RAD51-IF is feasible in routine clinical samples from patients with mPC and is associated with clinically relevant HRR gene alterations.

DDX39A resolves replication fork-associated RNA-DNA hybrids to balance fork protection and cleavage for genomic stability maintenance

Safeguarding replication fork stability in transcriptionally active regions is crucial for precise DNA replication and mutation prevention. Here, we discover the pervasive existence of replication fork-associated RNA-DNA hybrids (RF-RDs) in transcriptionally active regions of human cells. These hybrids function as protective barriers, preventing DNA2-mediated nascent DNA degradation and replication fork collapse under replication stress. We also identify DDX39A as a RAD51-associated protein that binds to stalled forks and resolves RF-RDs, facilitating proper DNA2-mediated DNA resection and replication fork restart. Excessive dissolution of RF-RDs causes replication fork collapse and genomic instability, while insufficient dissolution of RF-RDs under replication stress increases fork stability, resulting in chemoresistance that can be reversed by eliminating RF-RDs. In summary, we elucidated the prevalence of RF-RDs at replication forks within transcriptionally active regions, revealed their pivotal role in safeguarding replication fork stability, and proposed that targeting RF-RDs holds promise for augmenting chemotherapeutic efficacy.

Actionable alterations in glioblastoma: Insights from the implementation of genomic profiling as the standard of care from 2016 to 2023

Background

In 2016, genomic profiling was implemented for patients with grade 4 primary brain tumors at Rigshospitalet, Denmark. The aim of this study was to discover actionable alterations and to match these with targeted therapies.

Methods

Between January 2016 and December 2023, 483 brain tumor patients were profiled. We retrieved clinical data and molecular data. Whole exome, whole genome, or panel sequencing, along with SNP array analyses, and RNA-seq were performed on resected primary tumor tissue. Alterations were classified according to the European Society for Medical Oncology (ESMO) Scale for Clinical Actionability of Molecular Targets (ESCAT) following the European Association of Neuro-Oncology (EANO) guideline on rational molecular testing.

Results

A total of 200 (41.4%) patients' tumors harbored an alteration of interest according to the EANO guideline. Twenty (4.1%) patients had an ESCAT high-tier alteration (tier I or II), while 155 patients (32.1%) had an alteration corresponding to ESCAT IIIA. Thirty-five patients (7.2%) had an actionable alteration, and 15 (3.1%) received targeted therapy. The treated targets were BRAFV600E mutations, FGFR alterations, NTRK fusions, PDGFRA fusions, PTPRZ1-MET fusions, and TMB-high. The overall response rate was 20%, with a median duration of response of 12 months, and 47% achieved stable disease as the best response.

Conclusions

Genomic profiling uncovers alterations of interest in a substantial number of patients, but only a minority are considered by the Danish National Molecular Tumor Board to have actionable alterations, and even fewer receive targeted therapy. Nevertheless, factors, such as promising targets and the increasing availability of trials, may contribute to a future increase in the number of patients benefiting from targeted therapies based on genomic profiling.

Assessment of candidate high-grade serous ovarian carcinoma predisposition genes through integrated germline and tumour sequencing

High-grade serous ovarian carcinoma (HGSOC) has a significant hereditary component, only half of which is explained. Previously, we performed germline exome sequencing on BRCA1 and BRCA2-negative HGSOC patients, revealing three proposed and 43 novel candidate genes enriched with rare loss-of-function variants. For validation, we undertook case-control analyses using genomic data from disease-free controls. This confirms enrichment for nearly all previously identified genes. Additionally, one-hundred-and-eleven HGSOC tumours from variant carriers were sequenced alongside other complementary studies, seeking evidence of biallelic inactivation as supportive evidence. PALB2 and ATM validate as HGSOC predisposition genes, with 6/8 germline carrier tumours exhibiting biallelic inactivation accompanied by characteristic mutational signatures. Among candidate genes, only LLGL2 consistently shows biallelic inactivation and protein expression loss, supporting it as a novel HGSOC susceptibility gene. The remaining candidate genes fail to validate. Integrating case-control analyses with tumour sequencing is thus crucial for accurate gene discovery in familial cancer studies.

Evaluation of the Oncomine Comprehensive Assay Plus NGS Panel and the OncoScan CNV Assay for Homologous Recombination Deficiency Detection

INTRODUCTION

Testing for homologous recombination deficiency (HRD) as a biomarker in relation to poly (ADP-ribose) polymerase inhibitor (PARPi) treatment in ovarian cancer is done by sequencing of the BRCA1/2 genes and/or by assessing a genomic instability signature. Here we present data obtained with two different methods for genomic instability testing: the Oncomine™ Comprehensive Assay Plus (OCA Plus) NGS panel and the OncoScan CNV assay.

METHODS

The retrospective analytical study included 80 ovarian cancer samples of patients previously referred to clinical Myriad testing (reference cohort), and 50 ovarian cancer samples from patients collected as part of the Pelvic Mass study. OCA Plus NGS libraries were sequenced with the Ion S5™XL Sequencer and analyzed with the Ion Reporter™ Software v5.20 for calculation of the genomic instability metric (GIM). In addition, all samples were tested with the OncoScan CNV FFPE Assay and analyzed with a previously published R-algorithm for generation of an in-house genomic instability score (in-house GIS).

RESULTS

The OCA Plus assay had a concordance to the reference of 89% on samples with a tumor fraction ≥ 30% (auto-calculated or via molecular estimation). A total of 15 samples in the reference cohort had a calculated tumor fraction < 30% in the OCA Plus assay. In these, the concordance to reference was only 60%. For the OncoScan CNV in-house GIS a local cutoff point of ≥ 50 was calculated. This gave a concordance to the reference of 85%, with 91% of the samples in the reference cohort passing quality control (QC) on tumor fraction. Both assays had a high sensitivity for the detection of genomic instability in samples with pathogenic or likely pathogenic BRCA1/2 mutations, with 12/13 being GIM positive (OCA Plus assay) and 13/13 being in-house GIS positive (OncoScan CNV assay).

CONCLUSIONS

The OCA Plus assay and the OncoScan CNV assay show a high but not complete concordance to reference standard homologous recombination deficiency (HRD) detection. The main reason for QC failure or non-concordance in our study was a low tumor fraction estimated in the assay, despite the selection of material by a pathologist with an inclusion criterion of > 30% tumor. QC steps should include careful tumor content evaluation, and results on samples with < 30% tumor should not be reported.

Genomic scarring score predicts the response to PARP inhibitors in non-small cell lung cancer

PARP inhibitors (PARPi) have shown efficacy in tumours harbouring mutations in homologous recombination repair (HRR) genes. Somatic HRR mutations have been described in patients with Non-Small Cell Lung Cancer (NSCLC), but PARP inhibitors (PARPi) are not yet a therapeutic option. Here we assessed the homologous recombination status of early-stage NSCLC and explored the therapeutic benefit of PARPi in preclinical models. The Genomic Scarring Score GSS (GSS) and HRR mutation profile of 136 patients were assessed. High GSS (h-GSS) was observed in 39 (28.7%) patients half of which carried pathogenic/likely pathogenic somatic HRR mutations. TP53 mutations were significantly enriched in h-GSS tumours (p < 0.001). Olaparib significantly delayed tumour growth in h-GSS but not l-GSS Patient-derived Xenografts (PDXs), while patients with h-GSS/TP53mut tumours respond favourably to adjuvant platinum-based chemotherapy. Our functional data clearly support the idea that the use of GSS rather than the mutational status of HRR genes could select patients for administration of PARPi.

Dynamic changes in serum adenosine and the adenosine metabolism-based signature for prognosis in HER2-positive metastatic breast cancer patients

Aims

Adenosine metabolism in the breast cancer microenvironment is critical for tumor immunity. However, the prognostic significance of adenosine in breast cancer remains unclear. We aimed to dynamically monitor serum adenosine levels in patients with HER2-positive metastatic breast cancer (MBC) patients and to explore its predictive significance in trastuzumab therapy.

Methods

The sequencing and clinical data were downloaded from TCGA and GSE176078. Adenosine-related differentially expressed genes was analyzed by "DESeq2" package. Multivariate Cox and lasso-penalized Cox regressions were used to construct prognostic risk signatures. The risk scores were calculated from the identified expression of the hub genes. Bioinformatic analyses were performed using R with related packages. We also enrolled the metastatic breast cancer patients with HER2-positive from in our center and classified them into different groups according to the clinical outcomes assessed by enhanced CT. The adenosine levels were dynamically detected, and the difference in immune microenvironment between the subgroups was assessed by the immune cells that were recorded in our center.

Results

A total of 109 breast cancer patients with HER2-positive MBC were enrolled, and the expressions of 22 adenosine-related genes were filtered and matched from the TCGA database. The survival model based on the 15 differentially expressed genes was established, and the risk scores of each patient were the prognostic risk factors. Single-cell transcriptome sequencing data identified transcriptomic differences in patients with HER2-positive breast cancer. We also confirmed the predictive value of serum adenosine in the clinical progression of HER2-positive MBC patients. The different immune microenvironment between the subgroups supported the reliability of the predictive ability of adenosine in HER2-positive MBC patients.

Conclusions

The dynamic change of adenosine is a predictive biomarker for monitoring disease progression. The adenosine metabolism-based signature has the potential application in the prognosis of HER2-positive MBC patients.

Pan-Cancer Analysis of Homologous Recombination Deficiency in Cell Lines

SIGNIFICANCE

HRD is common in cancer and can be exploited therapeutically, as it sensitizes cells to DNA-damaging agents. Here, we scored more than 1,300 cancer cell lines for HRD using two different bioinformatic approaches, thereby enabling large-scale analyses that provide insights into the etiology and features of HRD.

Epigenetic editing of BRCA1 promoter increases cisplatin and olaparib sensitivity of ovarian cancer cells

Drug resistance is the primary contributor to the high mortality rate of ovarian cancer (OC). The loss of BRCA1/2 function is linked to drug sensitivity in OC cells. The aim of this study is to enhance the drug sensitivity of OC cells by inducing BRCA1 dysfunction through promoter epigenetic editing. Epigenetic regulatory regions within the BRCA1 promoter, affecting gene expression, were initially discerned through analysis of clinical samples. Subsequently, we designed and rigorously validated epigenetic editing tools. Ultimately, we evaluated the cisplatin and olaparib sensitivity of the OC cells after editing. The BRCA1 promoter contains two CpG-rich regions, with methylation of the region covering the transcription start site (TSS) strongly correlating with transcription and influencing OC development, prognosis, and homologous recombination (HR) defects. Targeting this region in OC cells using our designed epigenetic editing tools led to substantial and persistent DNA methylation changes, accompanied by significant reductions in H3K27ac histone modifications. This resulted in a notable suppression of BRCA1 expression and a decrease in HR repair capacity. Consequently, edited OC cells exhibited heightened sensitivity to cisplatin and olaparib, leading to increased apoptosis rates. Epigenetic inactivation of the BRCA1 promoter can enhance cisplatin and olaparib sensitivity of OC cells through a reduction in HR repair capacity, indicating the potential utility of epigenetic editing technology in sensitization therapy for OC.

Leveraging homologous recombination deficiency for sarcoma : Unravelling homologous recombination repair deficiency and therapeutic opportunities in soft tissue and bone sarcoma

BACKGROUND

Homologous recombination deficiency (HRD) in tumors correlates with poor prognosis and metastases development. Determining HRD is of major clinical relevance as it can be treated with PARP inhibitors (PARPi). HRD remains poorly investigated in sarcoma, a rare and heterogeneous cancer of mesenchymal origin.

OBJECTIVE

We aimed (i) to investigate predictive biomarkers of HRD in several independent sarcoma cohorts using a cross-functional strategy by combining genomic, transcriptomic and phenotypic approaches and (ii) to evaluate the therapeutic potential of PARPi and DNA damage response (DDR)-based therapies ex vivo.

MATERIALS AND METHODS

We performed a comprehensive genomic and transcriptomic characterization of sarcoma using datasets from The Cancer Genome Atlas (TCGA) and Therapeutically Applicable Research to Generate Effective Treatments (TARGET), and our own bone and soft tissue sarcoma cohorts. We evaluated PARP1/2 and WEE1 inhibition ex vivo in patient-derived sarcoma cell models as monotherapy and in combination with chemotherapeutic agents to identify synergistic effects.

RESULTS

Firstly, we identified genomic traits of HRD in a subset of sarcomas associated with molecular alterations in homologous recombination repair (HRR) pathway genes and high chromosomal instability. Secondly, we identified and validated distinct SARC-HRD transcriptional signatures that predicted sensitivity to PARPi. Finally, we showed functional defects in HRR in sarcoma cells that were associated with functional dependency towards PARPi and WEE1i and support the clinical use of RAD51 as a predictive biomarker for PARPi sensitivity.

CONCLUSION

We provide a personalized oncological approach to potentially improve the treatment of sarcoma patients. We encourage the evaluation of gene expression signatures to enhance the identification of patients who might benefit from DDR-based therapies.

Landscape of homologous recombination deficiency in gastric cancer and clinical implications for first-line chemotherapy

BACKGROUND

Homologous recombination deficiency (HRD) is one of the crucial hallmarks of cancer. It is associated with a favorable response to platinum-based chemotherapy. We explored the distinctive clinicopathological features of gastric cancer (GC) with HRD and the clinical significance of HRD in platinum-based first-line chemotherapy for unresectable metastatic GC.

METHODS

We enrolled 160 patients with GC in this study. Their tumor samples were subjected to genomic profiling utilizing targeted tumor sequencing. HRD was defined as the presence of alterations in any of 16 HR genes (BARD1, BLM, BRCA1, BRCA2, BRIP1, MRE11A, NBN, PALB2, PARP1, POLD1, RAD50, RAD51, RAD51C, RAD51D, WRN, and XRCC2). The clinicopathological features and treatment outcomes of first-line chemotherapy for unresectable metastatic GC were compared between HRD and non-HRD groups.

RESULTS

Forty-seven patients (29.4%) were classified into the HRD group. This group had a significantly lower proportion of macroscopic type 3 or 4 tumors and higher TMB than the non-HRD group. Among patients who underwent platinum-based first-line chemotherapy, the HRD group had a greater response rate and longer progression-free survival after treatment (median 8.0 months vs. 3.0 months, P = 0.010), with an adjusted hazard ratio of 0.337 (95% confidence interval 0.151-0.753). HRD status was not associated with treatment outcomes in patients who did not undergo platinum-based chemotherapy.

CONCLUSIONS

Low proportion of macroscopic type 3 or 4 tumors and a high TMB are distinctive features of GC with HRD. HRD status is a potential predictive marker in platinum-based first-line chemotherapy for unresectable metastatic GC.

Whole-exome profiles of inflammatory breast cancer and pathological response to neoadjuvant chemotherapy

BACKGROUND

Neoadjuvant chemotherapy (NACT) became a standard treatment strategy for patients with inflammatory breast cancer (IBC) because of high disease aggressiveness. However, given the heterogeneity of IBC, no molecular feature reliably predicts the response to chemotherapy. Whole-exome sequencing (WES) of clinical tumor samples provides an opportunity to identify genomic alterations associated with chemosensitivity.

METHODS

We retrospectively applied WES to 44 untreated IBC primary tumor samples and matched normal DNA. The pathological response to NACT, assessed on operative specimen, distinguished the patients with versus without pathological complete response (pCR versus no-pCR respectively). We compared the mutational profiles, spectra and signatures, pathway mutations, copy number alterations (CNAs), HRD, and heterogeneity scores between pCR versus no-pCR patients.

RESULTS

The TMB, HRD, and mutational spectra were not different between the complete (N = 13) versus non-complete (N = 31) responders. The two most frequently mutated genes were TP53 and PIK3CA. They were more frequently mutated in the complete responders, but the difference was not significant. Only two genes, NLRP3 and SLC9B1, were significantly more frequently mutated in the complete responders (23% vs. 0%). By contrast, several biological pathways involved in protein translation, PI3K pathway, and signal transduction showed significantly higher mutation frequency in the patients with pCR. We observed a higher abundance of COSMIC signature 7 (due to ultraviolet light exposure) in tumors from complete responders. The comparison of CNAs of the 3808 genes included in the GISTIC regions between both patients' groups identified 234 genes as differentially altered. The CIN signatures were not differentially represented between the complete versus non-complete responders. Based on the H-index, the patients with heterogeneous tumors displayed a lower pCR rate (11%) than those with less heterogeneous tumors (35%).

CONCLUSIONS

This is the first study aiming at identifying correlations between the WES data of IBC samples and the achievement of pCR to NACT. Our results, obtained in this 44-sample series, suggest a few subtle genomic alterations associated with pathological response. Additional investigations are required in larger series.

Impact of PARP inhibitors on progression-free survival in platinum-sensitive recurrent epithelial ovarian cancer: a retrospective analysis

OBJECTIVE

Poly (ADP-ribose) polymerase (PARP) inhibitors such as olaparib and niraparib have shown promise in extending progression-free survival (PFS) in patients with platinum-sensitive recurrent (PSR) epithelial ovarian cancer. In this retrospective study, we aimed to present our own data on the effect of PARP inhibitors on PFS in recurrent epithelial ovarian cancer.

METHODS

82 patients diagnosed with PSR epithelial ovarian, tubal, or primary peritoneal cancer between May 2017 and September 2023 were initially enrolled from our hospital. However, 16 patients had prior exposure to PARP inhibitors during primary treatment, and 11 were lost to follow-up. Consequently, the study focused on 55 eligible patients. PFS was compared between patients receiving PARP inhibitor maintenance therapy and those who did not.

RESULTS

Among the 55 patients with PSR epithelial ovarian cancer, 18 received olaparib as maintenance therapy, 19 received niraparib, and 18 opted for observation. PARP inhibitor therapy significantly extended PFS (mean 24.0 months) compared to observation (mean 9.0 months, p = 0.0005), regardless of BRCA mutation status (HR = 0.20, 95% CI: 0.08-0.50). Subgroup analysis showed no statistical difference between olaparib and niraparib. Additionally, there was no PFS difference based on BRCA mutation status within both PARP inhibitor groups.

CONCLUSION

Our retrospective study demonstrates that PARP inhibitor maintenance therapy, including olaparib and niraparib, significantly prolongs PFS in patients with PSR epithelial ovarian, tubal, or primary peritoneal cancer, These findings support the broad utilization of PARP inhibitors as a standard maintenance therapy for PSR epithelial ovarian cancer irrespective of BRCA mutation status.

Deep Learning Artificial Intelligence Predicts Homologous Recombination Deficiency and Platinum Response From Histologic Slides

PURPOSE

Cancers with homologous recombination deficiency (HRD) can benefit from platinum salts and poly(ADP-ribose) polymerase inhibitors. Standard diagnostic tests for detecting HRD require molecular profiling, which is not universally available.

METHODS

We trained DeepHRD, a deep learning platform for predicting HRD from hematoxylin and eosin (H&E)-stained histopathological slides, using primary breast (n = 1,008) and ovarian (n = 459) cancers from The Cancer Genome Atlas (TCGA). DeepHRD was compared with four standard HRD molecular tests using breast (n = 349) and ovarian (n = 141) cancers from multiple independent data sets, including platinum-treated clinical cohorts with RECIST progression-free survival (PFS), complete response (CR), and overall survival (OS) endpoints.

RESULTS

DeepHRD predicted HRD from held-out H&E-stained breast cancer slides in TCGA with an AUC of 0.81 (95% CI, 0.77 to 0.85). This performance was confirmed in two independent primary breast cancer cohorts (AUC, 0.76 [95% CI, 0.71 to 0.82]). In an external platinum-treated metastatic breast cancer cohort, samples predicted as HRD had higher complete CR (AUC, 0.76 [95% CI, 0.54 to 0.93]) with 3.7-fold increase in median PFS (14.4 v 3.9 months; P = .0019) and hazard ratio (HR) of 0.45 (P = .0047). There were no significant differences in nonplatinum treatment outcome by predicted HRD status in three breast cancer cohorts, including CR (AUC, 0.39) and PFS (HR, 0.98, P = .95) in taxane-treated metastatic breast cancer. Through transfer learning to high-grade serous ovarian cancer, DeepHRD-predicted HRD samples had better OS after first-line (HR, 0.46; P = .030) and neoadjuvant (HR, 0.49; P = .015) platinum therapy in two cohorts.

CONCLUSION

DeepHRD can predict HRD in breast and ovarian cancers directly from routine H&E slides across multiple external cohorts, slide scanners, and tissue fixation variables. When compared with molecular testing, DeepHRD classified 1.8- to 3.1-fold more patients with HRD, which exhibited better OS in high-grade serous ovarian cancer and platinum-specific PFS in metastatic breast cancer.

Deleterious alterations in homologous recombination repair genes and efficacy of platinum-based chemotherapy in biliary tract cancers

BACKGROUND

Platinum-based chemotherapy represents the standard first-line treatment for biliary tract cancers (BTC). Deficits in genes involved in the homologous recombination (HR) and DNA damage response (DDR) may confer higher sensitivity to platinum agents.

METHODS

We retrospectively included patients affected by BTC from 2 Italian institutions. Inclusion criteria consist of the receipt of platinum-based chemotherapy in the metastatic setting and the availability of comprehensive genomic profiling using next-generation sequencing (NGS). Patients were included in the HRD-like group if demonstrated oncogenic or likely oncogenic alterations in HR-/DDR-genes. Clinical endpoints were compared between the HRD-like group and the non-HRD-like group.

RESULTS

Seventy-four patients were included, of whom 25 (33%) in the HRD-like group and 49 (66%) in the non-HRD group. With a median follow-up of 26.04 months (interquartile-range [IQR] 9.41-29.27) in the HRD-like group and of 22.48 months (IQR 16.86-40.53) in the non-HRD group, no PFS difference emerged, with a mPFS of 5.18 months in the HRD-like group compared to 6.04 months in the non-HRD group (hazard ratio [HR], 1.017, 95% CI 0.58-1.78; P = .95). No differences were observed in DCR (64% [95 CI 45%-83%] vs 73% [95 CI 61%-86%]; P = .4), and CBR (45% [95% CI 28%-73%] vs 50% [95% CI, 37%-68%]; P = .9) between the HRD-like group and non-HRD groups, respectively. Median OS did not statistically differ between the HRD-like group and non-HRD group (26.7 vs 18.0 months, respectively; HR, 0.670, 0.33 to 1.37, P = .27).

CONCLUSION

HR-/DDR-genes, when assessed with regular tumor-only NGS panels, provide limited clinical validity to identify patients with BTC more likely to benefit from platinum-based chemotherapy.

Research on molecular characteristics of ADME-related genes in kidney renal clear cell carcinoma

Genes involved in drug absorption, distribution, metabolism, and excretion (ADME) are named ADME genes. However, the comprehensive role of ADME genes in kidney renal clear cell carcinoma (KIRC) remains unclear. Using the clinical and gene expression data of KIRC patients downloaded from The Cancer Genome Atlas (TCGA), ArrayExpress, and the Gene Expression Omnibus (GEO) databases, we cluster patients into two patterns, and the population with a relatively poor prognosis demonstrated higher level of immunosuppressive cell infiltration and higher proportion of glycolytic subtypes. Then, 17 ADME genes combination identified through the least absolute shrinkage and selection operator algorithm (LASSO, 1000 times) was utilized to calculate the ADME score. The ADME score was found to be an independent predictor of prognosis in KIRC and to be tightly associated with the infiltration level of immune cells, metabolic properties, tumor-related signaling pathways, genetic variation, and responses to chemotherapeutics. Our work revealed the characteristics of ADME in KIRC. Assessing the ADME profiles of individual patients can deepen our comprehension of tumor microenvironment (TME) features in KIRC and can aid in developing more personalized and effective therapeutic strategies.

AcornHRD: an HRD algorithm highly associated with anthracycline-based neoadjuvant chemotherapy in breast cancer in China

PURPOSE

Our study aimed to develop and validate a homologous recombination deficiency (HRD) scoring algorithm in the Chinese breast cancer population.

METHODS AND MATERIALS

Ninety-six in-house breast cancer (BC) samples and 6 HRD-positive standard cells were analyzed by whole-genome sequencing (WGS). Besides, 122 BCs from the TCGA database were down-sampled to ~ 1X WGS. We constructed an algorithm named AcornHRD for HRD score calculated based on WGS at low coverage as input data to estimate large-scale copy number alteration (LCNA) events on the genome. A clinical cohort of 50 BCs (15 cases carrying BRCA mutation) was used to assess the association between HRD status and anthracyclines-based neoadjuvant treatment outcomes.

RESULTS

A 100-kb window was defined as the optimal size using 41 in-house cases and the TCGA dataset. HRD score high threshold was determined as HRD score ≥ 10 using 55 in-house BCs with BRCA mutation to achieve a 95% BRCA-positive agreement rate. Furthermore, the HRD status agreement rate of AcornHRD is 100%, while the ShallowHRD is 60% in standard cells. BRCA mutation was significantly associated with a high HRD score evaluated by AcornHRD and ShallowHRD (p = 0.008 and p = 0.003, respectively) in the TCGA dataset. However, AcornHRD showed a higher positive agreement rate than did the ShallowHRD algorithm (70% vs 60%). In addition, the BRCA-positive agreement rate of AcornHRD was superior to that of ShallowHRD (87% vs 13%) in the clinical cohort. Importantly, the high HRD score assessed by AcornHRD was significantly correlated with a residual cancer burden score of 0 or 1 (RCB0/1). Besides, the HRD-positive group was more likely to respond to anthracycline-based chemotherapy than the HRD-negative group (pCR [OR = 9.5, 95% CI 1.11-81.5, p = 0.040] and RCB0/1 [OR = 10.29, 95% CI 2.02-52.36, p = 0.005]).

CONCLUSION

Using the AcornHRD algorithm evaluation, our analysis demonstrated the high performance of the LCNA genomic signature for HRD detection in breast cancers.

Prevalence of homologous recombination biomarkers in multiple tumor types: an observational study

Aim: To determine the prevalence of deleterious mutations in BRCA1 and BRCA2 and in 13 genes involved in homologous recombination repair (HRR), the prevalence of genomic loss of heterozygosity and the allelic and hereditary status of BRCA1, BRCA2 and other HRR gene mutations in multiple solid tumor types.Patients & methods: This was a retrospective observational study of patients with an advanced/metastatic diagnosis in one of 15 solid tumor types, who were identified in a real-world clinico-genomic database.Results: Tumor tissue samples from 9457 patients were analyzed, among which 4.7% had known or suspected deleterious BRCA1/2 mutations. The prevalence (range) of mutations in HRR genes was 13.6% (2.4%-26.0%) and genomic loss of heterozygosity ≥16% was 20.6% (2.6-34.4%) across all tumor types.Conclusion: The prevalence of mutations varied significantly depending on the type of tumor.

Detecting HRD in whole-genome and whole-exome sequenced breast and ovarian cancers

Breast and ovarian cancers harboring homologous recombination deficiency (HRD) are sensitive to PARP inhibitors and platinum chemotherapy. Conventionally, detecting HRD involves screening for defects in BRCA1, BRCA2, and other relevant genes. Recent analyses have shown that HRD cancers exhibit characteristic mutational patterns due to the activities of HRD-associated mutational signatures. At least three machine learning tools exist for detecting HRD based on mutational patterns. Here, using sequencing data from 1,043 breast and 182 ovarian cancers, we trained Homologous Recombination Proficiency Profiler (HRProfiler), a machine learning method for detecting HRD using six mutational features. HRProfiler's performance is assessed against prior approaches using additional independent datasets of 417 breast and 115 ovarian cancers, including retrospective data from a clinical trial involving patients treated with PARP inhibitors. Our results demonstrate that HRProfiler is the only tool that robustly and consistently predicts clinical response from whole-exome sequenced breast and ovarian cancers.

Association of tumor immune infiltration and prognosis with homologous recombination repair genes mutations in early triple-negative breast cancer

The aim of this study was to evaluate the mutation spectrum of homologous recombination repair (HRR) genes and its association with tumor immune infiltration and prognosis in triple-negative breast cancer (TNBC). TNBC patients (434 patients from Ruijin cohort) were evaluated with targeted next-generating sequencing for mutations in HRR genes. The frequencies of mutations were compared with public reference cohorts (320 TNBC patients from METABRIC, 105 from TCGA, and 225 from MSKCC 2018). Associations between mutation status and tumor immune infiltration and prognosis were analyzed. HRR genes mutations were seen in 21.89% patients, with BRCA1/2 mutations significantly enriched in tumors with breast/ovarian cancer family history (P = 0.025) and high Ki-67 levels (P = 0.018). HRR genes mutations were not related with recurrence-free survival (RFS) (adjusted P = 0.070) and overall survival (OS) (adjusted P = 0.318) for TNBC patients, regardless of carboplatin treatment (P > 0.05). Moreover, tumor immune infiltration and PD-L1 expression was positively associated with HRR or BRCA1/2 mutation (all P < 0.001). Patients with both HRR mutation and high CD8+ T cell counts had the best RFS and OS, whereas patients with no HRR mutation and low CD8+ T cell counts had the worst outcomes (RFS P < 0.001, OS P = 0.019). High frequency of HRR gene mutations was found in early TNBC, with no prognostic significance. Immune infiltration and PD-L1 expression was positively associated with HRR mutation, and both HRR mutation and high CD8+ T cell infiltration levels were associated with superior disease outcome.

AI powered quantification of nuclear morphology in cancers enables prediction of genome instability and prognosis

While alterations in nucleus size, shape, and color are ubiquitous in cancer, comprehensive quantification of nuclear morphology across a whole-slide histologic image remains a challenge. Here, we describe the development of a pan-tissue, deep learning-based digital pathology pipeline for exhaustive nucleus detection, segmentation, and classification and the utility of this pipeline for nuclear morphologic biomarker discovery. Manually-collected nucleus annotations were used to train an object detection and segmentation model for identifying nuclei, which was deployed to segment nuclei in H&E-stained slides from the BRCA, LUAD, and PRAD TCGA cohorts. Interpretable features describing the shape, size, color, and texture of each nucleus were extracted from segmented nuclei and compared to measurements of genomic instability, gene expression, and prognosis. The nuclear segmentation and classification model trained herein performed comparably to previously reported models. Features extracted from the model revealed differences sufficient to distinguish between BRCA, LUAD, and PRAD. Furthermore, cancer cell nuclear area was associated with increased aneuploidy score and homologous recombination deficiency. In BRCA, increased fibroblast nuclear area was indicative of poor progression-free and overall survival and was associated with gene expression signatures related to extracellular matrix remodeling and anti-tumor immunity. Thus, we developed a powerful pan-tissue approach for nucleus segmentation and featurization, enabling the construction of predictive models and the identification of features linking nuclear morphology with clinically-relevant prognostic biomarkers across multiple cancer types.

Homologous recombination proficient subtypes of high-grade serous ovarian cancer: treatment options for a poor prognosis group

Approximately 50% of tubo-ovarian high-grade serous carcinomas (HGSCs) have functional homologous recombination-mediated (HR) DNA repair, so-called HR-proficient tumors, which are often associated with primary platinum resistance (relapse within six months after completion of first-line therapy), minimal benefit from poly(ADP-ribose) polymerase (PARP) inhibitors, and shorter survival. HR-proficient tumors comprise multiple molecular subtypes including cases with CCNE1 amplification, AKT2 amplification or CDK12 alteration, and are often characterized as "cold" tumors with fewer infiltrating lymphocytes and decreased expression of PD-1/PD-L1. Several new treatment approaches aim to manipulate these negative prognostic features and render HR-proficient tumors more susceptible to treatment. Alterations in multiple different molecules and pathways in the DNA damage response are driving new drug development to target HR-proficient cancer cells, such as inhibitors of the CDK or P13K/AKT pathways, as well as ATR inhibitors. Treatment combinations with chemotherapy or PARP inhibitors and agents targeting DNA replication stress have shown promising preclinical and clinical results. New approaches in immunotherapy are also being explored, including vaccines or antibody drug conjugates. Many approaches are still in the early stages of development and further clinical trials will determine their clinical relevance. There is a need to include HR-proficient tumors in ovarian cancer trials and to analyze them in a more targeted manner to provide further evidence for their specific therapy, as this will be crucial in improving the overall prognosis of HGSC and ovarian cancer in general.

Leveraging Off-Target Reads in Panel Sequencing for Homologous Recombination Repair Deficiency Screening in Tumor

Targeted tumor only sequencing has become a standard practice in cancer diagnostics. This study aims to develop an approach for robust copy number variant calling in tumor samples using only off-target region (OTR) reads. We also established a clinical use case for homologous recombination deficiency (HRD) score estimation (HRDest) using the sum of telomeric-allelic imbalance and large-scale state transition scores without the need for loss of heterozygosity information. A strong correlation was found between HRD score and the sum of telomeric-allelic imbalance + large-scale state transition in The Cancer Genome Atlas cohort (ρ = 0.99, P < 2.2 × 10-16) and in a clinical in-house cohort of 34 tumors (ρ = 0.9, P = 5.1 × 10-13) comparing whole-exome sequencing and targeted sequencing data. HRDest scores from 1086 clinical cases were compared with The Cancer Genome Atlas data set. There were no significant differences in HRD score distribution within the analyzed tumor types. As a control, commercially available HRD standards were also sequenced, and the HRDest scores obtained from the OTR reads were well within the HRD reference range provided by the manufacturer. In conclusion, OTR reads of tumor-only panel sequencing can be used to determine genome-wide copy number variant profiles and to approximate HRD scores.

The DNA Damage Response (DDR) landscape of endometrial cancer defines discrete disease subtypes and reveals therapeutic opportunities

Genome maintenance is an enabling characteristic that allows neoplastic cells to tolerate the inherent stresses of tumorigenesis and evade therapy-induced genotoxicity. Neoplastic cells also deploy many mis-expressed germ cell proteins termed Cancer Testes Antigens (CTAs) to promote genome maintenance and survival. Here, we present the first comprehensive characterization of the DNA Damage Response (DDR) and CTA transcriptional landscapes of endometrial cancer in relation to conventional histological and molecular subtypes. We show endometrial serous carcinoma (ESC), an aggressive endometrial cancer subtype, is defined by gene expression signatures comprising members of the Replication Fork Protection Complex (RFPC) and Fanconi Anemia (FA) pathway and CTAs with mitotic functions. DDR and CTA-based profiling also defines a subset of highly aggressive endometrioid endometrial carcinomas (EEC) with poor clinical outcomes that share similar profiles to ESC yet have distinct characteristics based on conventional histological and genomic features. Using an unbiased CRISPR-based genetic screen and a candidate gene approach, we confirm that DDR and CTA genes that constitute the ESC and related EEC gene signatures are required for proliferation and therapy-resistance of cultured endometrial cancer cells. Our study validates the use of DDR and CTA-based tumor classifiers and reveals new vulnerabilities of aggressive endometrial cancer where none currently exist.

Biomimetic "nano-spears" for CAFs-targeting: splintered three "shields" with enhanced cisplatin anti-TNBC efficiency

The treatment dilemma of triple-negative breast cancer (TNBC) revolves around drug resistance and metastasis. Cancer-associated fibroblasts (CAFs) contribute to cisplatin (Cis) resistance and further metastasis in TNBC, making TNBC a difficult-to-treat disease. The dense stromal barrier which restricts drug delivery, invasive phenotype of tumor cells, and immunosuppressive tumor microenvironment (TME) induced by CAFs serve as three "shields" for TNBC against Cis therapy. Here, we designed a silybin-loaded biomimetic nanoparticle coated with anisamide-modified red blood cell membrane (ARm@SNP) as a "nanospear" for CAFs-targeting, which could shatter the "shields" and significantly exhibit inhibitory effect on 4T1 cells in combination with Cis both in vitro and in vivo. The ARm@SNP/Cis elicited 4T1 tumor growth arrest and destroyed three "shields" as follows: disintegrating the stromal barrier by inhibiting blood vessels growth and the expression of fibronectin; decreasing 4T1 cell invasion and metastasis by affecting the TGF-β/Twist/EMT pathway which impeded EMT activation; reversing the immunosuppressive microenvironment by increasing the activity and infiltration of immunocompetent cells. Based on CAFs-targeting, ARm@SNP reversed the resistance of Cis, remodeled the TME and inhibited invasion and metastasis while significantly improving the therapeutic effect of Cis on 4T1 tumor-bearing mice, providing a promising approach for treating intractable TNBC.

Luminal androgen receptor subtype and tumor-infiltrating lymphocytes groups based on triple-negative breast cancer molecular subclassification

In our previous study, we developed a triple-negative breast cancer (TNBC) subtype classification that correlated with the TNBC molecular subclassification. In this study, we aimed to evaluate the predictor variables of this subtype classification on the whole slide and to validate the model's performance by using an external test set. We explored the characteristics of this subtype classification and investigated genomic alterations, including genomic scar signature scores. First, TNBC was classified into the luminal androgen receptor (LAR) and non-luminal androgen receptor (non-LAR) subtypes based on the AR Allred score (≥ 6 and < 6, respectively). Then, the non-LAR subtype was further classified into the lymphocyte-predominant (LP), lymphocyte-intermediate (LI), and lymphocyte-depleted (LD) groups based on stromal tumor-infiltrating lymphocytes (TILs) (< 20%, > 20% but < 60%, and ≥ 60%, respectively). This classification showed fair agreement with the molecular classification in the test set. The LAR subtype was characterized by a high rate of PIK3CA mutation, CD274 (encodes PD-L1) and PDCD1LG2 (encodes PD-L2) deletion, and a low homologous recombination deficiency (HRD) score. The non-LAR LD TIL group was characterized by a high frequency of NOTCH2 and MYC amplification and a high HRD score.

Molecular characterization as new driver in prognostic signatures and therapeutic strategies for endometrial cancer

Endometrial cancer (EC) incidence and mortality rates have been increasing, particularly among young females. Although more than 90% of ECs are sporadic, 5-10% are hereditary, a majority of which occurs within Hereditary Non-Polyposis Colorectal Cancer syndrome (HNPCC) or Lynch syndrome. The traditional histopathological classification differentiates EC between two main groups: type I (or endometrioid) and type II (including all other histopathological subtypes). However, this classification lacks reproducibility and does not account for the emerging molecular heterogeneity. In 2013, The Cancer Genome Atlas (TCGA) project proposed EC molecular classification defining four groups with different prognostic and predictive values and the current international guidelines are progressively establishing EC risk stratification and treatment based on both histopathological and molecular criteria. Our manuscript aims to summarize the current state of EC molecular characterizations, including germline alterations at the basis of hereditary EC predisposition, to discuss their clinical utility as prognostic and predictive markers.

Mutational landscape of inflammatory breast cancer

BACKGROUND

Inflammatory breast cancer (IBC) is the most pro-metastatic form of BC. Better understanding of its enigmatic pathophysiology is crucial. We report here the largest whole-exome sequencing (WES) study of clinical IBC samples.

METHODS

We retrospectively applied WES to 54 untreated IBC primary tumor samples and matched normal DNA. The comparator samples were 102 stage-matched non-IBC samples from TCGA. We compared the somatic mutational profiles, spectra and signatures, copy number alterations (CNAs), HRD and heterogeneity scores, and frequencies of actionable genomic alterations (AGAs) between IBCs and non-IBCs. The comparisons were adjusted for the molecular subtypes.

RESULTS

The number of somatic mutations, TMB, and mutational spectra were not different between IBCs and non-IBCs, and no gene was differentially mutated or showed differential frequency of CNAs. Among the COSMIC signatures, only the age-related signature was more frequent in non-IBCs than in IBCs. We also identified in IBCs two new mutational signatures not associated with any environmental exposure, one of them having been previously related to HIF pathway activation. Overall, the HRD score was not different between both groups, but was higher in TN IBCs than TN non-IBCs. IBCs were less frequently classified as heterogeneous according to heterogeneity H-index than non-IBCs (21% vs 33%), and clonal mutations were more frequent and subclonal mutations less frequent in IBCs. More than 50% of patients with IBC harbored at least one high-level of evidence (LOE) AGA (OncoKB LOE 1-2, ESCAT LOE I-II), similarly to patients with non-IBC.

CONCLUSIONS

We provide the largest mutational landscape of IBC. Only a few subtle differences were identified with non-IBCs. The most clinically relevant one was the higher HRD score in TN IBCs than in TN non-IBCs, whereas the most intriguing one was the smaller intratumor heterogeneity of IBCs.

Transcriptional analysis of landmark molecular pathways in lung adenocarcinoma results in a clinically relevant classification with potential therapeutic implications

Lung adenocarcinoma (LUAD) is a molecularly heterogeneous disease. In addition to genomic alterations, cancer transcriptional profiling can be helpful to tailor cancer treatment and to estimate each patient's outcome. Transcriptional activity levels of 50 molecular pathways were inferred in 4573 LUAD patients using Gene Set Variation Analysis (GSVA) method. Seven LUAD subtypes were defined and independently validated based on the combined behavior of the studied pathways: AD (adenocarcinoma subtype) 1-7. AD1, AD4, and AD5 subtypes were associated with better overall survival. AD1 and AD4 subtypes were enriched in epidermal growth factor receptor (EGFR) mutations, whereas AD2 and AD6 showed higher tumor protein p53 (TP53) alteration frequencies. AD2 and AD6 subtypes correlated with higher genome instability, proliferation-related pathway expression, and specific sensitivity to chemotherapy, based on data from LUAD cell lines. LUAD subtypes were able to predict immunotherapy response in addition to CD274 (PD-L1) gene expression and tumor mutational burden (TMB). AD2 and AD4 subtypes were associated with potential resistance and response to immunotherapy, respectively. Thus, analysis of transcriptomic data could improve patient stratification beyond genomics and single biomarkers (i.e., PD-L1 and TMB) and may lay the foundation for more personalized treatment avenues, especially in driver-negative LUAD.

Molecular subtypes of endometrial cancer: Implications for adjuvant treatment strategies

BACKGROUND

When determining adjuvant treatment for endometrial cancer, the decision typically relies on factors such as cancer stage, histologic grade, subtype, and a few histopathologic markers. The Cancer Genome Atlas revealed molecular subtyping of endometrial cancer, which can provide more accurate prognostic information and guide personalized treatment plans.

OBJECTIVE

To summarize the expression and molecular basis of the main biomarkers of endometrial cancer.

SEARCH STRATEGY

PubMed was searched from January 2000 to March 2023.

SELECTION CRITERIA

Studies evaluating molecular subtypes of endometrial cancer and implications for adjuvant treatment strategies.

DATA COLLECTION AND ANALYSIS

Three authors independently performed a comprehensive literature search, collected and extracted data, and assessed the methodological quality of the included studies.

MAIN RESULTS

We summarized the molecular subtyping of endometrial cancer, including mismatch repair deficient, high microsatellite instability, polymerase epsilon (POLE) exonuclease domain mutated, TP53 gene mutation, and non-specific molecular spectrum. We also summarized planned and ongoing clinical trials and common therapy methods in endometrial cancer. POLE mutated endometrial cancer consistently exhibits favorable patient outcomes, regardless of adjuvant therapy. Genomic similarities between p53 abnormality endometrial cancer and high-grade serous ovarian cancer suggested possible overlapping treatment strategies. High levels of immune checkpoint molecules, such as programmed cell death 1 and programmed cell death 1 ligand 1 can counterbalance mismatch repair deficient endometrial cancer immune phenotype. Hormonal treatment is an appealing option for high-risk non-specific molecular spectrum endometrial cancers, which are typically endometrioid and hormone receptor positive. Combining clinical and pathologic characteristics to guide treatment decisions for patients, including concurrent radiochemotherapy, chemotherapy, inhibitor therapy, endocrine therapy, and immunotherapy, might improve the management of endometrial cancer and provide more effective treatment options for patients.

CONCLUSIONS

We have characterized the molecular subtypes of endometrial cancer and discuss their value in terms of a patient-tailored therapy in order to prevent significant under- or overtreatment.

New therapeutic targets for endometrial cancer: a glimpse into the preclinical sphere

INTRODUCTION

Endometrial cancer (EC) is the only gynecologic malignancy showing increasing trends in incidence and mortality. While standard treatment has been effective primarily for early-stage EC, precision medicine with tailored therapy has revolutionized the management of this disease. Genome sequencing analyses have identified four sub-types of EC. Treatments for primary and metastatic disease can now be tailored more accurately to achieve better oncologic results.

AREAS COVERED

This review provides an overview of the most relevant and updated evidence in the literature regarding EC molecular analysis and its role in risk classification, prognostication, and guidance for tailored and target therapies in early and advanced/metastatic stages. In addition, it provides updated information on optimal surgical management based on molecular classification and highlights key advances and future strategies.

EXPERT OPINION

EC molecular analysis yields the potential of tailoring adjuvant treatment by escalating or deescalating therapy, as shown for POLE-mutated and p53-mutated tumors. Moreover, the expression of specific molecular signatures offers the possibility to employ novel target therapies, such as immune-checkpoint inhibitors that have demonstrated a significant benefit on prognosis. New treatment guidelines are still being established, and ongoing studies are exploring the potential prognostic role of further sub-stratifications of the four molecular classes and treatment options.

Performance of a RAD51-based functional HRD test on paraffin-embedded breast cancer tissue

PURPOSE

BRCA-deficient breast cancers (BC) are highly sensitive to platinum-based chemotherapy and PARP inhibitors due to their deficiency in the homologous recombination (HR) pathway. However, HR deficiency (HRD) extends beyond BRCA-associated BC, highlighting the need for a sensitive method to enrich for HRD tumors in an alternative way. A promising approach is the use of functional HRD tests which evaluate the HR capability of tumor cells by measuring RAD51 protein accumulation at DNA damage sites. This study aims to evaluate the performance of a functional RAD51-based HRD test for the identification of HRD BC.

METHODS

The functional HR status of 63 diagnostic formalin-fixed paraffin-embedded (FFPE) BC samples was determined by applying the RAD51-FFPE test. Samples were screened for the presence of (epi)genetic defects in HR and matching tumor samples were analyzed with the RECAP test, which requires ex vivo irradiated fresh tumor tissue on the premise that the HRD status as determined by the RECAP test faithfully represented the functional HR status.

RESULTS

The RAD51-FFPE test identified 23 (37%) of the tumors as HRD, including three tumors with pathogenic variants in BRCA1/2. The RAD51-FFPE test showed a sensitivity of 88% and a specificity of 76% in determining the HR-class as defined by the RECAP test.

CONCLUSION

Given its high sensitivity and compatibility with FFPE samples, the RAD51-FFPE test holds great potential to enrich for HRD tumors, including those associated with BRCA-deficiency. This potential extends to situations where DNA-based testing may be challenging or not easily accessible in routine clinical practice. This is particularly important considering the potential implications for treatment decisions and patient stratification.

Nucleotide excision repair deficiency is a targetable therapeutic vulnerability in clear cell renal cell carcinoma

Due to a demonstrated lack of DNA repair deficiencies, clear cell renal cell carcinoma (ccRCC) has not benefitted from targeted synthetic lethality-based therapies. We investigated whether nucleotide excision repair (NER) deficiency is present in an identifiable subset of ccRCC cases that would render those tumors sensitive to therapy targeting this specific DNA repair pathway aberration. We used functional assays that detect UV-induced 6-4 pyrimidine-pyrimidone photoproducts to quantify NER deficiency in ccRCC cell lines. We also measured sensitivity to irofulven, an experimental cancer therapeutic agent that specifically targets cells with inactivated transcription-coupled nucleotide excision repair (TC-NER). In order to detect NER deficiency in clinical biopsies, we assessed whole exome sequencing data for the presence of an NER deficiency associated mutational signature previously identified in ERCC2 mutant bladder cancer. Functional assays showed NER deficiency in ccRCC cells. Some cell lines showed irofulven sensitivity at a concentration that is well tolerated by patients. Prostaglandin reductase 1 (PTGR1), which activates irofulven, was also associated with this sensitivity. Next generation sequencing data of the cell lines showed NER deficiency-associated mutational signatures. A significant subset of ccRCC patients had the same signature and high PTGR1 expression. ccRCC cell line-based analysis showed that NER deficiency is likely present in this cancer type. Approximately 10% of ccRCC patients in the TCGA cohort showed mutational signatures consistent with ERCC2 inactivation associated NER deficiency and also substantial levels of PTGR1 expression. These patients may be responsive to irofulven, a previously abandoned anticancer agent that has minimal activity in NER-proficient cells.

Widespread BRCA1/2-independent homologous recombination defects are caused by alterations in RNA-binding proteins

Defects in homologous recombination DNA repair (HRD) both predispose to cancer development and produce therapeutic vulnerabilities, making it critical to define the spectrum of genetic events that cause HRD. However, we found that mutations in BRCA1/2 and other canonical HR genes only identified 10%-20% of tumors that display genomic evidence of HRD. Using a networks-based approach, we discovered that over half of putative genes causing HRD originated outside of canonical DNA damage response genes, with a particular enrichment for RNA-binding protein (RBP)-encoding genes. These putative drivers of HRD were experimentally validated, cross-validated in an independent cohort, and enriched in cancer-associated genome-wide association study loci. Mechanistic studies indicate that some RBPs are recruited to sites of DNA damage to facilitate repair, whereas others control the expression of canonical HR genes. Overall, this study greatly expands the repertoire of known drivers of HRD, with implications for basic biology, genetic screening, and therapy stratification.

The DNA Damage Response (DDR) landscape of endometrial cancer defines discrete disease subtypes and reveals therapeutic opportunities

Genome maintenance is an enabling characteristic that allows neoplastic cells to tolerate the inherent stresses of tumorigenesis and evade therapy-induced genotoxicity. Neoplastic cells also deploy mis-expressed germ cell proteins termed Cancer Testes Antigens (CTAs) to promote genome maintenance and survival. Here, we present the first comprehensive characterization of the DNA Damage Response (DDR) and CTA transcriptional landscapes of endometrial cancer in relation to conventional histological and molecular subtypes. We show endometrial serous carcinoma (ESC), an aggressive endometrial cancer subtype, is defined by gene expression signatures comprising members of the Replication Fork Protection Complex (RFPC) and Fanconi Anemia (FA) pathway and CTAs with mitotic functions. DDR and CTA- based profiling also defines a subset of highly aggressive endometrioid endometrial carcinomas (EEC) with poor clinical outcomes that share similar profiles to ESC yet have distinct characteristics based on conventional histological and genomic features. Using an unbiased CRISPR-based genetic screen and a candidate gene approach, we confirm that DDR and CTA genes that constitute the ESC and related EEC gene signatures are required for proliferation and therapy-resistance of cultured endometrial cancer cells. Our study validates the use of DDR and CTA-based tumor classifiers and reveals new vulnerabilities of aggressive endometrial cancer where none currently exist.

Mutant RB1 enhances therapeutic efficacy of PARPis in lung adenocarcinoma by triggering the cGAS/STING pathway

Poly (ADP-ribose) polymerase inhibitors (PARPis) are approved for cancer therapy according to their synthetic lethal interactions, and clinical trials have been applied in non-small cell lung cancer. However, the therapeutic efficacy of PARPis in lung adenocarcinoma (LUAD) is still unknown. We explored the effect of a mutated retinoblastoma gene (RB1) on PARPi sensitivity in LUAD. Bioinformatic screening was performed to identify PARPi-sensitive biomarkers. Here, we showed that viability of LUAD cell lines with mutated RB1 was significantly decreased by PARPis (niraparib, rucaparib, and olaparib). RB1 deficiency induced genomic instability, prompted cytosolic double-stranded DNA (dsDNA) formation, activated the cGAS/STING pathway, and upregulated downstream chemokines CCL5 and CXCL10, triggering immune cell infiltration. Xenograft experiments indicated that PARPi treatment reduced tumorigenesis in RB1-KO mice. Additionally, single-cell RNA sequencing analysis showed that malignant cells with downregulated expression of RB1 had more communications with other cell types, exhibiting activation of specific signaling such as GAS, IFN response, and antigen-presenting and cytokine activities. Our findings suggest that RB1 mutation mediates the sensitivity to PARPis through a synthetic lethal effect by triggering the cGAS/STING pathway and upregulation of immune infiltration in LUAD, which may be a potential therapeutic strategy.

Multi-scale characterisation of homologous recombination deficiency in breast cancer

BACKGROUND

Homologous recombination is a robust, broadly error-free mechanism of double-strand break repair, and deficiencies lead to PARP inhibitor sensitivity. Patients displaying homologous recombination deficiency can be identified using 'mutational signatures'. However, these patterns are difficult to reliably infer from exome sequencing. Additionally, as mutational signatures are a historical record of mutagenic processes, this limits their utility in describing the current status of a tumour.

METHODS

We apply two methods for characterising homologous recombination deficiency in breast cancer to explore the features and heterogeneity associated with this phenotype. We develop a likelihood-based method which leverages small insertions and deletions for high-confidence classification of homologous recombination deficiency for exome-sequenced breast cancers. We then use multinomial elastic net regression modelling to develop a transcriptional signature of heterogeneous homologous recombination deficiency. This signature is then applied to single-cell RNA-sequenced breast cancer cohorts enabling analysis of homologous recombination deficiency heterogeneity and differential patterns of tumour microenvironment interactivity.

RESULTS

We demonstrate that the inclusion of indel events, even at low levels, improves homologous recombination deficiency classification. Whilst BRCA-positive homologous recombination deficient samples display strong similarities to those harbouring BRCA1/2 defects, they appear to deviate in microenvironmental features such as hypoxic signalling. We then present a 228-gene transcriptional signature which simultaneously characterises homologous recombination deficiency and BRCA1/2-defect status, and is associated with PARP inhibitor response. Finally, we show that this signature is applicable to single-cell transcriptomics data and predict that these cells present a distinct milieu of interactions with their microenvironment compared to their homologous recombination proficient counterparts, typified by a decreased cancer cell response to TNFα signalling.

CONCLUSIONS

We apply multi-scale approaches to characterise homologous recombination deficiency in breast cancer through the development of mutational and transcriptional signatures. We demonstrate how indels can improve homologous recombination deficiency classification in exome-sequenced breast cancers. Additionally, we demonstrate the heterogeneity of homologous recombination deficiency, especially in relation to BRCA1/2-defect status, and show that indications of this feature can be captured at a single-cell level, enabling further investigations into interactions between DNA repair deficient cells and their tumour microenvironment.

Aligning germline and somatic mutations in prostate cancer. Are genetics changing practice?

OBJECTIVE

To review the current status of germline and somatic (tumour) genetic testing for prostate cancer (PCa), and its relevance for clinical practice.

METHODS

A narrative synthesis of various molecular profiles related to their clinical context was carried out. Current guidelines for genetic testing and its feasibility in clinical practice were analysed. We report the main identified genetic sequencing results or functional genomic scores for PCa published in the literature or obtained from the French PROGENE study.

RESULTS

The molecular alterations observed in PCa are mostly linked to disruption of the androgen receptor (AR) pathway or DNA repair deficiency. The main known germline mutations affect the BReast CAncer gene 2 (BRCA2) and homeobox B13 (HOXB13) genes, whereas AR and tumour protein p53 (TP53) are the genes with most frequent somatic alterations in tumours from men with metastatic PCa. Molecular tests are now available for detecting some of these germline or somatic alterations and sometimes recommended by guidelines, but their utilisation must combine rationality and feasibility. They can guide specific therapies, notably for the management of metastatic disease. Indeed, following androgen deprivation, targeted therapies for PCa currently include poly-(ADP-ribose)-polymerase (PARP) inhibitors, immune checkpoint inhibitors, and prostate-specific membrane antigen (PSMA)-guided radiotherapy. The genetic tests currently approved for targeted therapies remain limited to the detection of BRCA1 and BRCA2 mutation and DNA mismatch repair deficiency, while large panels are recommended for germline analyses, not only for inherited cancer predisposing syndrome, but also for metastatic PCa.

CONCLUSIONS

Further consensus aligning germline with somatic molecular analysis in metastatic PCa is required, including genomics scars, emergent immunohistochemistry, or functional pre-screen imaging. With rapid advances in knowledge and technology in the field, continuous updating of guidelines to help the clinical management of these individuals, and well-conducted studies to evaluate the benefits of genetic testing are needed.

Combination of genomic instability score and TP53 status for prognosis prediction in lung adenocarcinoma

The genomic instability (GI) /homologous recombination deficiency (HRD) score, calculated as the sum of the events of loss of heterozygosity (LOH), large-scale state transition (LST) and telomere allele imbalance (TAI), is used to guide the choice of treatment in several cancers, but its relationship with genomic features, clinicopathological characteristics and prognosis in lung cancer is poorly understood, which could lead to population bias in prospective studies. We retrospectively analyzed 1011 lung cancer patients whose tumor samples were successfully profiled by high-throughput sequencing panel including GI/HRD score. Alterations of many cancer suppressor genes were associated with higher GI/HRD scores, biallelic inactivation of TP53 was correlated with a high GI/HRD score. A combination of two gene alterations exhibited a higher GI/HRD scores than single gene alterations. The GI/HRD score was associated with advanced stages in lung adenocarcinoma but not in lung squamous cell carcinoma. Furthermore, patients with higher GI/HRD scores had significantly shorter overall survival and progression-free survival than patients with lower GI/HRD scores. Finally, patients with a combination of a higher GI/HRD scores and TP53 alteration exhibited an extremely poor prognosis compared with patients with a lower GI/HRD scores and wild-type TP53 (overall survival, training cohort, hazard ratio (HR) = 8.56, P < 0.001; validation cohort, HR = 6.47, P < 0.001; progression-free survival, HR = 4.76, P < 0.001). Our study revealed the prognostic value of the GI/HRD score in lung adenocarcinoma, but not for all lung cancer. Moreover, the combination of the GI/HRD score and TP53 status could be a promising strategy to predict the prognosis of patients with lung adenocarcinoma.

A Benchmark of In-House Homologous Recombination Repair Deficiency Testing Solutions for High-Grade Serous Ovarian Cancer Diagnosis

Homologous recombination deficiency (HRD) has become an important prognostic and predictive biomarker for patients with high-grade serous ovarian cancer who may benefit from poly-ADP ribose polymerase inhibitors (PARPi) and platinum-based therapies. HRD testing provides relevant information to personalize patients' treatment options and has been progressively incorporated into diagnostic laboratories. Here, we assessed the performance of an in-house HRD testing system deployable in a diagnostic clinical setting, comparing results from two commercially available next-generation sequencing (NGS)-based tumor tests (SOPHiA DDMTM HRD Solution and AmoyDx® (HRD Focus Panel)) with the reference assay from Myriad MyChoice® (CDx). A total of 85 ovarian cancer samples were subject to HRD testing. An overall strong correlation was observed across the three assays evaluated, regardless of the different underlying methods employed to assess genomic instability, with the highest pairwise correlation between Myriad and SOPHiA (R = 0.87, p-value = 3.39 × 10-19). The comparison of the assigned HRD status to the reference Myriad's test revealed a positive predictive value (PPV) and negative predictive value (NPV) of 90.9% and 96.3% for SOPHiA's test, while AmoyDx's test achieved 75% PPV and 100% NPV. This is the largest HRD testing evaluation using different methodologies and provides a clear picture of the robustness of NGS-based tests currently offered in the market. Our data shows that the implementation of in-house HRD testing in diagnostic laboratories is technically feasible and can be reliably performed with commercial assays. Also, the turnaround time is compatible with clinical needs, making it an ideal alternative to offer to a broader number of patients while maintaining high-quality standards at more accessible price tiers.

Patient Assessment and Therapy Planning Based on Homologous Recombination Repair Deficiency

Defects in genes involved in the DNA damage response cause homologous recombination repair deficiency (HRD). HRD is found in a subgroup of cancer patients for several tumor types, and it has a clinical relevance to cancer prevention and therapies. Accumulating evidence has identified HRD as a biomarker for assessing the therapeutic response of tumor cells to poly(ADP-ribose) polymerase inhibitors and platinum-based chemotherapies. Nevertheless, the biology of HRD is complex, and its applications and the benefits of different HRD biomarker assays are controversial. This is primarily due to inconsistencies in HRD assessments and definitions (gene-level tests, genomic scars, mutational signatures, or a combination of these methods) and difficulties in assessing the contribution of each genomic event. Therefore, we aim to review the biological rationale and clinical evidence of HRD as a biomarker. This review provides a blueprint for the standardization and harmonization of HRD assessments.

Molecular Classification Predicts Response to Radiotherapy in the Randomized PORTEC-1 and PORTEC-2 Trials for Early-Stage Endometrioid Endometrial Cancer

PURPOSE

The molecular classification of endometrial cancer (EC) has proven to have prognostic value and is predictive of response to adjuvant chemotherapy. Here, we investigate its predictive value for response to external beam radiotherapy (EBRT) and vaginal brachytherapy (VBT) in early-stage endometrioid EC (EEC).

METHODS

Data of the randomized PORTEC-1 trial (n = 714) comparing pelvic EBRT with no adjuvant therapy in early-stage intermediate-risk EC and the PORTEC-2 trial (n = 427) comparing VBT with EBRT in early-stage high-intermediate-risk EC were used. Locoregional (including vaginal and pelvic) recurrence-free survival was compared between treatment groups across the four molecular classes using Kaplan-Meier's methodology and log-rank tests.

RESULTS

A total of 880 molecularly classified ECs, 484 from PORTEC-1 and 396 from PORTEC-2, were included. The majority were FIGO-2009 stage I EEC (97.2%). The median follow-up was 11.3 years. No locoregional recurrences were observed in EC with a pathogenic mutation of DNA polymerase-ε (POLEmut EC). In mismatch repair-deficient (MMRd) EC, locoregional recurrence-free survival was similar after EBRT (94.2%), VBT (94.2%), and no adjuvant therapy (90.3%; P = .74). In EC with a p53 abnormality (p53abn EC), EBRT (96.9%) had a substantial benefit over VBT (64.3%) and no adjuvant therapy (72.2%; P = .048). In EC with no specific molecular profile (NSMP EC), both EBRT (98.3%) and VBT (96.2%) yielded better locoregional control than no adjuvant therapy (87.7%; P < .0001).

CONCLUSION

The molecular classification of EC predicts response to radiotherapy in stage I EEC and may guide adjuvant treatment decisions. Omitting radiotherapy seems to be safe in POLEmut EC. The benefit of radiotherapy seems to be limited in MMRd EC. EBRT yields a significantly better locoregional recurrence-free survival than VBT or no adjuvant therapy in p53abn EC. VBT is the treatment of choice for NSMP EC as it is as effective as EBRT and significantly better than no adjuvant therapy for locoregional tumor control.