Selective CDK7 Inhibition Suppresses Cell Cycle Progression and MYC Signaling While Enhancing Apoptosis in Therapy-resistant Estrogen Receptor-positive Breast Cancer.

PURPOSE: Resistance to endocrine therapy (ET) and CDK4/6 inhibitors (CDK4/6i) is a clinical challenge in estrogen receptor (ER)-positive (ER+) breast cancer. Cyclin-dependent kinase 7 (CDK7) is a candidate target in endocrine-resistant ER+ breast cancer models and selective CDK7 inhibitors (CDK7i) are in clinical development for the treatment of ER+ breast cancer. Nonetheless, the precise mechanisms responsible for the activity of CDK7i in ER+ breast cancer remain elusive. Herein, we sought to unravel these mechanisms. EXPERIMENTAL DESIGN: We conducted multi-omic analyses in ER+ breast cancer models in vitro and in vivo, including models with different genetic backgrounds. We also performed genome-wide CRISPR/Cas9 knockout screens to identify potential therapeutic vulnerabilities in CDK4/6i-resistant models. RESULTS: We found that the on-target antitumor effects of CDK7 inhibition in ER+ breast cancer are in part p53 dependent, and involve cell cycle inhibition and suppression of c-Myc. Moreover, CDK7 inhibition exhibited cytotoxic effects, distinctive from the cytostatic nature of ET and CDK4/6i. CDK7 inhibition resulted in suppression of ER phosphorylation at S118; however, long-term CDK7 inhibition resulted in increased ER signaling, supporting the combination of ET with a CDK7i. Finally, genome-wide CRISPR/Cas9 knockout screens identified CDK7 and MYC signaling as putative vulnerabilities in CDK4/6i resistance, and CDK7 inhibition effectively inhibited CDK4/6i-resistant models. CONCLUSIONS: Taken together, these findings support the clinical investigation of selective CDK7 inhibition combined with ET to overcome treatment resistance in ER+ breast cancer. In addition, our study highlights the potential of increased c-Myc activity and intact p53 as predictors of sensitivity to CDK7i-based treatments.

Stereotactic radiosurgery for brain metastases arising from gynecological malignancies: A retrospective treatment outcome analysis.

BACKGROUND: This retrospective study aims to assess the efficacy of stereotactic radiosurgery (SRS) in the treatment of brain metastases (BM) originating from gynecological cancers. It focuses on local control (LC), distant tumor control (DTC), and overall survival (OS). METHODS: The analysis comprised 18 individuals with gynecological-origin BM treated with SRS at the Hadassah Medical Center from 2004 to 2021. Statistical analyses evaluate factors impacting LC, DTC, and OS. RESULTS: A total of 36 BM of gynecological origin underwent SRS. The median age at the first SRS treatment was 60 years, with a median time of 24.5 months from the primary malignancy diagnosis to BM detection. The 12-month LC rate per patient was 84.6 %, and 5.6 % per BM. Only two instances of local recurrence were observed. The DTC at 12 months was 75 %, with a 29 % overall. Non-significant trends indicating a correlation with distant brain failure with increased cumulative volume and the occurrence of craniotomy before SRS. The median OS of the cohort was 16.5 months from SRS treatment. The 6, 12, 18, and 24-month survival rates were 77.8 %, 66.7 %, 50 %, and 22.2 % respectively. Higher number of BM was associated with lower OS (p = 0.046). On multivariate analysis, age was a significant factor for OS (p = 0.03), demonstrating that older age was associated with a more favorable prognosis. CONCLUSION: This study supports SRS effectiveness for treating BM from gynecological cancers and suggests similar outcomes to more common malignancies.

First Female Patient with a Rare CIC-FOXO4-Translocated Sarcoma: A Case Report.

Small round cell sarcoma is a group of undifferentiated malignancies arising in the bone and soft tissue, notable for Ewing sarcoma. Recently, a new World Health Organization classification has been introduced, including an additional subset of these sarcomas, named CIC-rearranged sarcoma. Within this group, CIC-FOXO4 translocation is an exceedingly rare fusion that has been reported only 4 times in the literature. Herein, we report in-depth the pathological, clinical, and molecular features of a CIC-FOXO4 translocation-driven tumor in a 46-year-old woman.

Clinician's guide to targeted estrogen receptor degradation using PROTAC in patients with estrogen receptor-positive metastatic breast cancer.

PURPOSE OF REVIEW: Metastatic breast cancer (MBC) remains a major clinical challenge, necessitating the development of innovative therapeutic strategies. Estrogen receptor (ER) degradation using proteolysis-targeting chimeras (PROTAC) has emerged as a promising approach for overcoming acquired resistance to endocrine therapy. This review will summarize recent findings, highlighting the role of ER degradation by PROTAC in patients with MBC. RECENT FINDINGS: The application of PROTAC technology for ER degradation has demonstrated initial success in preclinical and early clinical studies. PROTACs, consisting of an ER-targeting moiety, an E3 ubiquitin ligase-recruiting moiety, and a linker, facilitate ER ubiquitination and subsequent proteasomal degradation. Yet, significant challenges persist in the clinical translation of ER degradation by PROTAC. These include the optimization of PROTAC design, elucidation of mechanisms underlying resistance to PROTAC-induced ER degradation, and identification of predictive biomarkers for patient stratification. Additionally, addressing potential off-target effects and toxicity profiles remains a critical aspect of developing PROTAC-based therapies. SUMMARY: Recent data demonstrate the potential of ER degradation by PROTAC as a therapeutic strategy for patients with MBC. Continued research efforts and development of synergistic combinations are crucial for further advancing PROTAC-based therapies and improving outcomes in patients with MBC.

Liquid biopsy for brain metastases and leptomeningeal disease in patients with breast cancer.

A significant subset of patients with metastatic breast cancer develops brain metastasis. As efficacy of systemic therapies has improved and patients live longer with metastatic breast cancer, the incidence of breast cancer brain metastases has increased. Brain metastases pose a clinical challenge in diagnosis, treatment, and monitoring across all breast cancer subtypes, and better tools are needed. Liquid biopsy, which enables minimally invasive sampling of a patient's cancer, has the potential to shed light on intra-cranial tumor biology and to improve patient care by enabling therapy tailoring. Here we review current evidence for the clinical validity of liquid biopsy in patients with breast cancer brain metastases, with a focus on circulating tumor cells and circulating tumor DNA.

Distinct breast cancer phenotypes in BRCA 1/2 carriers based on ER status.

PURPOSE: BRCA1/2 genes are the two main genes associated with hereditary breast cancers (BC). In the present study, we explore clinical and molecular characteristics of BRCA-associated BC in relation to estrogen receptor (ER) status. METHODS: Three BC databases (DB) were evaluated: (i) Hadassah oncogenetics (n = 4826); (ii) METABRIC (n = 1980), and (iii) Nick-Zainal (n = 560). We evaluated age at diagnosis in BRCA positive (BP) and BRCA negative (BN) patients, and tested for mutational signature differences in cohort iii. mRNA differential expression analysis (DEA) and pathway analysis were performed in cohort ii. RESULTS: Age at diagnosis was lower in BP vs. BN tumors in all cohorts in the ER- group, and only in cohort i for the ER + group. Signature 3 was universal in BP BC, whereas several signatures were associated with ER status. Pathway analysis was performed between BP&BN, and was significant only in ER- tumors: the major activated pathways involved cancer-related processes and were highly significant. The most significant pathway was estrogen-mediated S-phase entry and the most activated upstream regulator was ERBB2. CONCLUSION: Signature 3 was universal for all BP BC, while other signatures were associated with ER status. ER + BP& BN show similar genomic characteristics, ER- BP differed markedly from BN. This suggests that the initial carcinogenic process is universal for all BRCA carriers, but further insults lead to the development of two genomically distinct subtypes ER- and ER + . This may shed light on possible mechanisms involved in BP and carry preventive and therapeutic implications.

The Clinical Utility of ESR1 Mutations in Hormone Receptor-Positive, HER2-Negative Advanced Breast Cancer.

The estrogen receptor is a key driver of estrogen receptor-positive breast cancers. Accumulating evidence indicates that the ESR1 ligand-binding domain mutations have an important role in acquired endocrine resistance, mainly to treatment with aromatase inhibitors. The identification, monitoring, and targeting of ESR1 mutations is an evolving field of major interest given the potential of improved outcomes in metastatic hormone receptor-positive breast cancers. Herein, the authors review the current evidence and rationale for exploiting the ESR1 mutations as a potential biomarker and therapeutic target. The authors discuss the role of ESR1 testing and current therapeutic efforts to target these mutations.

ESR1 activating mutations: From structure to clinical application.

Estrogen receptor-positive breast cancer is the most common type of both early and advanced breast cancer. Estrogen receptor alpha (ER) is a nuclear hormone receptor and a key driver of tumorigenesis and tumor progression in these breast cancers. As such, it is a key treatment target and a biomarker predictive of response to endocrine therapy. Activating ESR1 ligand binding domain mutations engender constitutive/ligand independent transcriptional activities and emerge following prolonged first-line hormone therapy regimens, mainly from aromatase inhibitors. The full scale of the biological and clinical significance of these mutations continue to evolve and additional studies are required to further discern the multimodal effects of these mutations on ER transcription, metastatic propensity, and the tumor microenvironment. Furthermore, recent and ongoing studies highlight the potential clinical utility of these mutations as therapeutic targets and dynamic biomarkers. Herein, we review the structure, functional consequences, and clinical implications of the activating ESR1 mutations in advanced estrogen receptor-positive breast cancer.

A universal cell-free DNA approach for response prediction to preoperative chemoradiation in rectal cancer.

The standard treatment approach for stage II/III rectal cancer is neoadjuvant chemoradiation therapy (nCRT) followed by surgery. In recent years, new treatment approaches have led to higher rates of complete tumor eradication combined with organ-preservation strategies. However, better tools are still needed to personalize therapy for the individual patient. In this prospective observational study, we analyzed colon-derived cell-free (cf)DNA (c-cfDNA) using a tissue-specific DNA methylation signature, and its association with therapy outcomes. Analyzing plasma samples (n = 303) collected during nCRT from 37 patients with locally advanced rectal cancer (LARC), we identified colon-specific methylation markers that discriminated healthy individuals from patients with untreated LARC (area under the curve, 0.81; 95% confidence interval, 0.70-0.92; P < .0001). Baseline c-cfDNA predicted tumor response, with increased levels linked to larger residual cancer. c-cfDNA measured after the first week of therapy identified patients with maximal response and complete cancer eradication, who had significantly lower c-cfDNA compared with those who had residual disease (8.6 vs 57.7 average copies/ml, respectively; P = .013). Increased c-cfDNA after 1 week of therapy was also associated with disease recurrence. Methylation-based liquid biopsy can predict nCRT outcomes and facilitate patient selection for escalation and de-escalation strategies.

Multiplexed, single-molecule, epigenetic analysis of plasma-isolated nucleosomes for cancer diagnostics.

The analysis of cell-free DNA (cfDNA) in plasma provides information on pathological processes in the body. Blood cfDNA is in the form of nucleosomes, which maintain their tissue- and cancer-specific epigenetic state. We developed a single-molecule multiparametric assay to comprehensively profile the epigenetics of plasma-isolated nucleosomes (EPINUC), DNA methylation and cancer-specific protein biomarkers. Our system allows for high-resolution detection of six active and repressive histone modifications and their ratios and combinatorial patterns on millions of individual nucleosomes by single-molecule imaging. In addition, our system provides sensitive and quantitative data on plasma proteins, including detection of non-secreted tumor-specific proteins, such as mutant p53. EPINUC analysis of a cohort of 63 colorectal cancer, 10 pancreatic cancer and 33 healthy plasma samples detected cancer with high accuracy and sensitivity, even at early stages. Finally, combining EPINUC with direct single-molecule DNA sequencing revealed the tissue of origin of colorectal, pancreatic, lung and breast tumors. EPINUC provides multilayered information of potential clinical relevance from limited (<1 ml) liquid biopsy material.

Clinical Efficacy and Whole-Exome Sequencing of Liquid Biopsies in a Phase IB/II Study of Bazedoxifene and Palbociclib in Advanced Hormone Receptor-Positive Breast Cancer.

PURPOSE: Sensitivity to endocrine therapy (ET) is critical for the clinical benefit from the combination of palbociclib plus ET in hormone receptor-positive/HER2-negative (HR+/HER2-) advanced breast cancer. Bazedoxifene is a third-generation selective estrogen receptor (ER) modulator and selective ER degrader with activity in preclinical models of endocrine-resistant breast cancer, including models harboring ESR1 mutations. Clinical trials in healthy women showed that bazedoxifene is well tolerated. PATIENTS AND METHODS: We conducted a phase Ib/II study of bazedoxifene plus palbociclib in patients with HR+/HER2- advanced breast cancer who progressed on prior ET (N = 36; NCT02448771). RESULTS: The study met its primary endpoint, with a clinical benefit rate of 33.3%, and the safety profile was consistent with what has previously been seen with palbociclib monotherapy. The median progression-free survival (PFS) was 3.6 months [95% confidence interval (CI), 2.0-7.2]. An activating PIK3CA mutation at baseline was associated with a shorter PFS (HR = 4.4; 95% CI, 1.5-13; P = 0.0026), but activating ESR1 mutations did not impact the PFS. Longitudinal plasma circulating tumor DNA whole-exome sequencing (WES; N = 68 plasma samples) provided an overview of the tumor heterogeneity and the subclonal genetic evolution, and identified actionable mutations acquired during treatment. CONCLUSIONS: The combination of palbociclib and bazedoxifene has clinical efficacy and an acceptable safety profile in a heavily pretreated patient population with advanced HR+/HER2- breast cancer. These results merit continued investigation of bazedoxifene in breast cancer.

Booster doses of COVID-19 vaccines for patients with haematological and solid cancer: a systematic review and individual patient data meta-analysis.

IMPORTANCE: Patients with cancer have an increased risk of severe disease and mortality from COVID-19, as the disease and antineoplastic therapy cause reduced vaccine immunogenicity. Booster doses have been proposed to enhance protection, and efficacy data are emerging from several studies. OBJECTIVE: To evaluate the proportion of COVID-19 primary vaccination non-responders with cancer who seroconvert after a booster dose. METHODS: PubMed, EMBASE, CENTRAL and medRxiv were searched from 1st January 2021 to 10th March 2022. Quality was assessed using the Joanna Briggs Institute Critical Appraisal checklist. RESULTS: After the eligibility assessment, 22 studies were included in this systematic review and 17 for meta-analysis of seroconversion in non-responders, pooling a total of 849 patients with haematological cancer and 82 patients with solid cancer. Haematological cancer non-responders exhibited lower seroconversion at 44% (95% CI 36-53%) than solid cancer at 80% (95% CI 69-87%). Individual patient data meta-analysis found the odds of having a meaningful rise in antibody titres to be significantly associated with increased duration between the second and third dose (OR 1.02, 95% CI 1.00-1.03, P ≤ 0.05), age of patient (OR 0.960, 95% CI 0.934-0.987, P ≤ 0.05) and cancer type. With patients with haematological cancer as a reference, patients with lung cancer had 16.8 times the odds of achieving a meaningful increase in antibody titres (OR 16.8, 95% CI 2.95-318, P ≤ 0.05) and gastrointestinal cancer patients had 25.4 times the odds of achieving a meaningful increase in antibody titres (OR 25.4, 95% CI 5.26-492.21, P ≤ 0.05). CONCLUSIONS: administration of a COVID-19 vaccine booster dose is effective in improving seroconversion and antibody levels. Patients with haematological cancer consistently demonstrate poorer response to booster vaccines than patients with solid cancer.

Breast Cancer with Low Recurrence Score on Oncotype DX©: Interplay Between Early Recurrence, Lobular Histology and BRCA Mutation.

INTRODUCTION: The 21-gene recurrence score assay Oncotype DX© (ODX) has clear prognostic and predictive value regarding adjuvant chemotherapy. However, recent studies have shown the clinical distinctiveness of both BRCA1/2-driven early breast cancer (EBC) and invasive lobular (ILC) breast cancers. We evaluated the association between BRCA1/2-driven EBC/ILC and Oncotype DX failure despite a recurrence score ≤ 20. METHODS: Here, we describe a small cohort of 16 patients from our center who, despite a low recurrence score (RS) ≤ 20, suffered from early disease recurrence. Clinical parameters of our cohort of patients were compared to a cohort from the general population of Clalit Health Service (CHS). RESULTS: Median age at diagnosis in our cohort was significantly younger. BRCA mutational status was available in 14 patients in our cohort. A high percentage of these patients had BRCA1/2 mutations (35.7%), either germline (in 3) or somatic (in 2). Half of our cohort was diagnosed with lobular carcinoma (ILC) relative to 10-15% in the general population of BC (p = 0.02). The median time to recurrence was 44 months. CONCLUSION: BRCA1/2 mutation and ILC are highly represented in this cohort. Although our cohort is small, these data may suggest that a RS ≤ 20 in these subgroups may not reflect a low risk of recurrence.

[THE LIQUID BIOPSY REVOLUTION IN BREAST CANCER - APPLICATIONS AND POSSIBILITIES].

INTRODUCTION: Over the past two decades there have been significant developments in the fields of laboratory technology, genetics and bioinformatics. These developments have raised the attractiveness of liquid biopsy - a test aimed to detect tumor markers in body fluids. One of the liquid biopsy methods is based on identification of circulating tumor DNA - fragments of DNA originating from the tumor which are evident in the bloodstream - revealing the various tumor characteristics via simple blood tests. This novel approach has several advantages over the traditional biopsy: it is noninvasive and thus more convenient and safer for the patient; it reflects the characteristics of the entire tumor tissue present in the patient's body in a single test; it is performed quickly and safely by a phlebotomist and does not rely on the subjective interpretation of the pathologist. The liquid biopsy is a highly valuable tool for the diagnosis and monitoring of cancer, which can be recruited for the clinical management of breast cancer - the most common malignancy in females which is estimated to affect one in every eight women. In this review we will present the existing and the potential applications of the liquid biopsy in breast cancer patients, regarding the various settings of patient care - diagnosis, treatment and follow-up.

Potential Refinement of Recurrence Score by pSTAT3 Status.

The likelihood of recurrence in breast cancer patients with hormone receptor-positive (HR-positive) tumors is influenced by clinical, histopathological, and molecular features. Recent studies suggested that activated STAT3 (pSTAT3) might serve as a biomarker of outcome in breast cancer patients. In the present work, we have analyzed the added value of pSTAT3 to OncotypeDx Recurrence Score (RS) in patient prognostication. We have found that patients with low RS (<26) and low pSTAT3 might represent a population at a higher risk for cancer recurrence. Furthermore, we have observed that a positive pSTAT3 score alone can be a favorable marker for patients with HR-positive breast cancer under the age of 50. In an era of personalized medicine, these findings warrant further appraisal of chemotherapy benefit in this population.

Ex vivo organotypic cultures for synergistic therapy prioritization identify patient-specific responses to combined MEK and Src inhibition in colorectal cancer.

Translating preclinical studies to effective treatment protocols and identifying specific therapeutic responses in individuals with cancer is challenging. This may arise due to the complex genetic makeup of tumor cells and the impact of their multifaceted tumor microenvironment on drug response. To find new clinically relevant drug combinations for colorectal cancer (CRC), we prioritized the top five synergistic combinations from a large in vitro screen for ex vivo testing on 29 freshly resected human CRC tumors and found that only the combination of mitogen-activated protein kinase kinase (MEK) and proto-oncogene tyrosine-protein kinase Src (Src) inhibition was effective when tested ex vivo. Pretreatment phosphorylated Src (pSrc) was identified as a predictive biomarker for MEK and Src inhibition only in the absence of KRASG12 mutations. Overall, we demonstrate the potential of using ex vivo platforms to identify drug combinations and discover MEK and Src dual inhibition as an effective drug combination in a predefined subset of individuals with CRC.

Liquid biopsy reveals collateral tissue damage in cancer.

Cancer inflicts damage to surrounding normal tissues, which can culminate in fatal organ failure. Here, we demonstrate that cell death in organs affected by cancer can be detected by tissue-specific methylation patterns of circulating cell-free DNA (cfDNA). We detected elevated levels of hepatocyte-derived cfDNA in the plasma of patients with liver metastases originating from different primary tumors, compared with cancer patients without liver metastases. In addition, patients with localized pancreatic or colon cancer showed elevated hepatocyte cfDNA, suggesting liver damage inflicted by micrometastatic disease, by primary pancreatic tumor pressing the bile duct, or by a systemic response to the primary tumor. We also identified elevated neuron-, oligodendrocyte-, and astrocyte-derived cfDNA in a subpopulation of patients with brain metastases compared with cancer patients without brain metastasis. Cell type-specific cfDNA methylation markers enabled the identification of collateral tissue damage in cancer, revealing the presence of metastases in specific locations and potentially assisting in early cancer detection.

Restoring order at the cell cycle border: Co-targeting CDK4/6 and CDK2.

Overcoming resistance to CDK4/6 inhibitors is a major clinical challenge. In this issue of Cancer Cell, Freeman-Cook et al. study mechanisms of resistance to CDK4/6 inhibitors by employing a CRISPRa screen. They identify the cyclin E-CDK2 axis and Myc signaling as key pathways of resistance and develop PF-06873600, a selective CDK2/4/6 inhibitor.