Serial circulating tumor DNA monitoring of CDK4/6 inhibitors response in metastatic breast cancer

Modulation of the tumor microenvironment and mechanism of immunotherapy-based drug resistance in breast cancer

Breast cancer, the most frequent female malignancy, is often curable when detected at an early stage. The treatment of metastatic breast cancer is more challenging and may be unresponsive to conventional therapy. Immunotherapy is crucial for treating metastatic breast cancer, but its resistance is a major limitation. The tumor microenvironment (TME) is vital in modulating the immunotherapy response. Various tumor microenvironmental components, such as cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs), are involved in TME modulation to cause immunotherapy resistance. This review highlights the role of stromal cells in modulating the breast tumor microenvironment, including the involvement of CAF-TAM interaction, alteration of tumor metabolism leading to immunotherapy failure, and other latest strategies, including high throughput genomic screening, single-cell and spatial omics techniques for identifying tumor immune genes regulating immunotherapy response. This review emphasizes the therapeutic approach to overcome breast cancer immune resistance through CAF reprogramming, modulation of TAM polarization, tumor metabolism, and genomic alterations.

Genomic Landscape of Circulating Tumor DNA in Patients With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-2-Negative Metastatic Breast Cancer Treated With Abemaciclib: Data From the SCRUM-Japan Cancer Genome Screening Project

PURPOSE

To understand the mutational landscape of circulating tumor DNA (ctDNA) and tumor tissue of patients with hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer (MBC) treated with abemaciclib + endocrine therapy (ET).

METHODS

Blood samples for ctDNA and/or tissue samples were collected from abemaciclib-treated patients with HR+/HER2- MBC enrolled in the SCRUM-Japan MONSTAR-SCREEN project. Blood samples were collected before abemaciclib initiation (baseline) and at disease progression/abemaciclib discontinuation (post abemaciclib treatment). Clinical and genomic characteristics including neoplastic burden (measured by shedding rate and maximum variant allele frequency [VAF]) were assessed at baseline. Genomic alterations in ctDNA were compared in paired baseline and post abemaciclib treatment samples.

RESULTS

All patients (N = 97) were female (median age, 57 years [IQR, 50-67]). In baseline ctDNA (n = 77), PIK3CA (37%), TP53 (28%), ESR1 (16%), and GATA3 (11%) were the most frequently mutated genes. Baseline tissue samples (n = 79) showed similar alteration frequencies. Among patients with baseline ctDNA data, 30% had received previous ET. ESR1 alteration frequency (35% v 8%; P < .01), median shedding rate (3 v 2), and maximum somatic VAF (4 v 0.8; both P < .05) were significantly higher in ctDNA from patients with previous ET than those without previous ET. In paired ctDNA samples (n = 33), PIK3CA and ESR1 alteration frequencies were higher after abemaciclib treatment than at baseline, though not statistically significant. Among the post-treatment alterations, those newly acquired were detected most frequently in FGF3/4/19 (18%); PIK3CA, TP53, CCND1, and RB1 (all 15%); and ESR1 (12%).

CONCLUSION

We summarized the ctDNA and cancer tissue mutational landscape, including overall neoplastic burden and PIK3CA and ESR1 hotspot mutations in abemaciclib-treated patients with HR+/HER2- MBC. The data provide insights that could help optimize treatment strategies in this population.

Predictive and prognostic biomarkers of bone metastasis in breast cancer: current status and future directions

The most common site of metastasis in breast cancer is the bone, where the balance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation is disrupted. This imbalance causes osteolytic bone metastasis in breast cancer, which leads to bone pain, pathological fractures, spinal cord compression, and other skeletal-related events (SREs). These complications reduce patients' quality of life significantly and have a profound impact on prognosis. In this review, we begin by providing a brief overview of the epidemiology of bone metastasis in breast cancer, including current diagnostic tools, treatment approaches, and existing challenges. Then, we will introduce the pathophysiology of breast cancer bone metastasis (BCBM) and the animal models involved in the study of BCBM. We then come to the focus of this paper: a discussion of several biomarkers that have the potential to provide predictive and prognostic value in the context of BCBM-some of which may be particularly compatible with more comprehensive liquid biopsies. Beyond that, we briefly explore the potential of new technologies such as single-cell sequencing and organoid models, which will improve our understanding of tumor heterogeneity and aid in the development of improved biomarkers. The emerging biomarkers discussed hold promise for future clinical application, aiding in the prevention of BCBM, improving the prognosis of patients, and guiding the implementation of personalized medicine.

Precision medicine in gastroenteropancreatic neuroendocrine neoplasms: Where are we in 2023?

Precision medicine describes a target-related approach to tailoring diagnosis and treatment of the individual patient. While this personalized approach is revoluzionizing many areas of oncology, it is quite late in the field of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs), in which there are few molecular alterations to be therapeutically targeted. We critically reviewed the current evidence about precision medicine in GEP NENs, focusing on potential clinically relevant actionable targets for GEP NENs, such as the mTOR pathway, MGMT, hypoxia markers, RET, DLL-3, and some general agnostic targets. We analysed the main investigational approaches with solid and liquid biopsies. Furthermore, we reviewed a model of precision medicine more specific for NENs that is the theragnostic use of radionuclides. Overall, currently no true predictive factors for therapy have been validated so far in GEP NENs, and the personalized approach is based more on clinical thinking within a NEN-dedicated multidisciplinary team. However, there is a robust background to suppose that precision medicine, with the theragnostic model will yield new insights in this context soon.

Potential value of ctDNA monitoring in metastatic HR + /HER2 - breast cancer: longitudinal ctDNA analysis in the phase Ib MONALEESASIA trial

BACKGROUND

There is increasing interest in the use of liquid biopsies, but data on longitudinal analyses of circulating tumor DNA (ctDNA) remain relatively limited. Here, we report a longitudinal ctDNA analysis of MONALEESASIA, a phase Ib trial evaluating the efficacy and safety of ribociclib plus endocrine therapy (ET) in Asian patients with hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer.

METHODS

MONALEESASIA enrolled premenopausal and postmenopausal Japanese and postmenopausal non-Japanese Asian patients. All patients received ribociclib with ET (letrozole, fulvestrant, or tamoxifen with goserelin). ctDNA was analyzed using a targeted next-generation sequencing panel of 572 cancer-related genes and correlated by best overall response (BOR).

RESULTS

Five hundred seventy-four cell-free DNA samples from 87 patients were tested. The most frequently altered genes at baseline included PIK3CA (29%) and TP53 (22%). Treatment with ribociclib plus ET decreased ctDNA in most patients at the first on-treatment time point, regardless of dose or ET partner. Patients with partial response and stable disease had lower ctDNA at baseline that remained low until data cutoff if no progressive disease occurred. Most patients with progressive disease as the best response had higher ctDNA at baseline that remained high at the end of treatment. For patients with partial response and stable disease with subsequent progression, ctDNA increased towards the end of treatment in most patients, with a median lead time of 83 days (14-309 days). In some patients with BOR of partial response who experienced disease progression later, specific gene alterations and total ctDNA fraction increased; this was sometimes observed concurrently with the development of new lesions without a change in target lesion size. Patients with alterations in PIK3CA and TP53 at baseline had shorter median progression-free survival compared with patients with wild-type PIK3CA and TP53, 12.7 and 7.3 months vs 19.2 and 19.4 months, respectively (P = .016 and P = .0001, respectively).

CONCLUSIONS

Higher ctDNA levels and PIK3CA and TP53 alterations detected at baseline were associated with inferior outcomes. On-treatment ctDNA levels were associated with different patterns based on BOR. Longitudinal tracking of ctDNA may be useful for monitoring tumor status and detection of alterations with treatment implications.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02333370 . Registered on January 7, 2015.

HR+/HER2- Advanced Breast Cancer Treatment in the First-Line Setting: Expert Review

The approval of CDK4/6 inhibitors has dramatically improved care for the treatment of HR+/HER2- advanced breast cancer, but navigating the rapidly-expanding treatment evidence base is challenging. In this narrative review, we provide best-practice recommendations for the first-line treatment of HR+/HER2- advanced breast cancer in Canada based on relevant literature, clinical guidelines, and our own clinical experience. Due to statistically significant improvements in overall survival and progression-free survival, ribociclib + aromatase inhibitor is our preferred first-line treatment for de novo advanced disease or relapse ≥12 months after completion of adjuvant endocrine therapy and ribociclib or abemaciclib + fulvestrant is our preferred first-line treatment for patients experiencing early relapse. Abemaciclib or palbociclib may be used when alternatives to ribociclib are needed, and endocrine therapy can be used alone in the case of contraindication to CDK4/6 inhibitors or limited life expectancy. Considerations for special populations-including frail and fit elderly patients, as well as those with visceral disease, brain metastases, and oligometastatic disease-are also explored. For monitoring, we recommend an approach across CDK4/6 inhibitors. For mutational testing, we recommend routinely performing ER/PR/HER2 testing to confirm the subtype of advanced disease at the time of progression and to consider ESR1 and PIK3CA testing for select patients. Where possible, engage a multidisciplinary care team to apply evidence in a patient-centric manner.

Position paper on CDK4/6 inhibitors in early breast cancer

Inhibitors of the cyclin-dependent kinases 4/6 (CDK4/6i) have been practice-changing and are now considered the standard of care in combination with endocrine therapy for the first- or second-line treatment in advanced hormone-receptor-positive, human epidermal growth factor receptor 2‑negative breast cancer. Recently, CDK4/6i have also emerged as an appealing targeted cancer therapy in early breast cancer, however results of large clinical trials are controversial. This position paper summarizes the evidence, and provides guidance for clinical practice.

Tumor-informed or tumor-agnostic circulating tumor DNA as a biomarker for risk of recurrence in resected colorectal cancer patients

Introduction

Circulating tumor DNA (ctDNA) has been increasingly recognized as a promising minimally-invasive biomarker that could identify patients with minimal residual disease and a high risk of recurrence after definitive treatment. In this study, we've compared the clinical utility and sensitivity of 2 different approaches to ctDNA analyses: tumor-informed and tumor-agnostic in the management of colorectal (CRC) patients. The clinical benefits of a single timepoint ctDNA analysis compared to serial ctDNA monitoring after definitive treatment were also evaluated to uncover the ideal surveillance protocol.

Methods

Patient-paired resected tumor tissues, peripheral blood cells, and a total of 127 pre-operative and serial plasma cell-free DNA (cfDNA) samples after definitive treatment from 38 CRC patients that had undergone curative intent surgery were analyzed using a commercial NGS cfDNA panel.

Results

Up to 84% (32/38) of the recruited patients were detected with at least 1 genomic alteration from the tumor tissues that could be monitored using the tumor-informed ctDNA approach and none of the detected alterations were clonal hematopoiesis (CH) related. In contrast, 37% (14/38) of patients were detected with at least 1 monitoring alteration after exclusion of CH mutations using the tumor-agnostic approach. Serial plasma samples after definitive therapy were available for 31 patients. In the landmark ctDNA analysis, 24% (7/29) of patients had detectable ctDNA and were more likely to relapse than ctDNA-negative patients (p < 0.05). The landmark analysis sensitivity and specificity for recurrence were 67% and 87%, respectively. The incorporation of longitudinal ctDNA analysis at 6-months intervals improved the sensitivity to 100%. The median variant allele frequency (VAF) of the ctDNA mutations detected during surveillance was 0.028% (range: 0.018-0.783), where up to 80% (8/10) of the mutations were detected at VAF lower than the tumor-agnostic detection limit of 0.1%. Utilizing the tumor-agnostic approach reduced the recurrence detection sensitivity to 67% (4/6). Serial ctDNA analyses predicted disease recurrence at a median of 5 months ahead of radiological imaging.

Conclusion

Longitudinal monitoring using tumor-informed ctDNA testing shows high analytical sensitivity, low probability of false-positive results due to CH mutations, and improved sensitivity in detecting recurrence which may modify the clinical management of CRC.

Circulating tumour DNA dynamics for assessment of molecular residual disease and for intercepting resistance in breast cancer

PURPOSE OF REVIEW

Longitudinal evaluation of circulating tumour DNA (ctDNA) represents a promising tool for monitoring tumour evolution. In patients with breast cancer, ctDNA dynamics for the assessment of molecular residual disease (MRD) and resistances may, respectively, help clinicians in treatment modulation of adjuvant treatments, and in anticipating resistance to ongoing treatments and switch treatments before clinical progression, to improve disease control. Anyway, the introduction of this dynamic biomarker into clinical practice requires the demonstration of analytical validity, clinical validity and clinical utility.

RECENT FINDINGS

In early breast cancer setting, several observational studies demonstrated the clinical validity of MRD monitoring through ctDNA in identifying patients at a higher risk of relapse, but many clinical trials evaluating the clinical utility are still ongoing, and few data resulted in inconclusive results.Instead, ctDNA dynamics for intercepting resistance have not been fully evaluated in terms of clinical validity, because monitoring schedules of most observational studies are not intensive. The only trial assessing their clinical utility (PADA-1) demonstrated a benefit in terms of progression-free survival, portraying a new landscape for clinical trials in this space.

SUMMARY

Rigorous clinical trials with adequate assays and patient-relevant endpoints are paramount to demonstrate the clinical utility of ctDNA dynamics and eventually increase clinical outcomes.

Liquid Biopsy as a Tool for the Diagnosis, Treatment, and Monitoring of Breast Cancer

Breast cancer (BC) is a highly heterogeneous disease. The treatment of BC is complicated owing to intratumoral complexity. Tissue biopsy and immunohistochemistry are the current gold standard techniques to guide breast cancer therapy; however, these techniques do not assess tumoral molecular heterogeneity. Personalized medicine aims to overcome these biological and clinical complexities. Advances in techniques and computational analyses have enabled increasingly sensitive, specific, and accurate application of liquid biopsy. Such progress has ushered in a new era in precision medicine, where the objective is personalized treatment of breast cancer, early screening, accurate diagnosis and prognosis, relapse detection, longitudinal monitoring, and drug selection. Liquid biopsy can be defined as the sampling of components of tumor cells that are released from a tumor and/or metastatic deposits into the blood, urine, feces, saliva, and other biological substances. Such components include circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) or circulating tumor RNA (ctRNA), platelets, and exosomes. This review aims to highlight the role of liquid biopsy in breast cancer and precision medicine.

Circulating Tumor DNA-Based Genomic Profiling Assays in Adult Solid Tumors for Precision Oncology: Recent Advancements and Future Challenges

Genomic profiling using tumor biopsies remains the standard approach for the selection of approved molecular targeted therapies. However, this is often limited by its invasiveness, feasibility, and poor sample quality. Liquid biopsies provide a less invasive approach while capturing a contemporaneous and comprehensive tumor genomic profile. Recent advancements in the detection of circulating tumor DNA (ctDNA) from plasma samples at satisfactory sensitivity, specificity, and detection concordance to tumor tissues have facilitated the approval of ctDNA-based genomic profiling to be integrated into regular clinical practice. The recent approval of both single-gene and multigene assays to detect genetic biomarkers from plasma cell-free DNA (cfDNA) as companion diagnostic tools for molecular targeted therapies has transformed the therapeutic decision-making procedure for advanced solid tumors. Despite the increasing use of cfDNA-based molecular profiling, there is an ongoing debate about a 'plasma first' or 'tissue first' approach toward genomic testing for advanced solid malignancies. Both approaches present possible advantages and disadvantages, and these factors should be carefully considered to personalize and select the most appropriate genomic assay. This review focuses on the recent advancements of cfDNA-based genomic profiling assays in advanced solid tumors while highlighting the major challenges that should be tackled to formulate evidence-based guidelines in recommending the 'right assay for the right patient at the right time'.