Characterization of circulating tumor cells in early breast cancer patients receiving neoadjuvant chemotherapy

Preclinical evaluation of the theranostic potential of 89Zr/177Lu-labeled anti-TROP-2 antibody in triple-negative breast cancer model

BACKGROUND

Triple-negative breast cancer (TNBC) is one of the most lethal malignant tumors among women, characterized by high invasiveness, high heterogeneity, and lack of specific therapeutic targets such as estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Trophoblast cell-surface antigen-2 (TROP-2) is a transmembrane glycoprotein over-expressed in 80% of TNBC patients and is associated with the occurrence, progress, and poor prognosis of TNBC. The TROP-2 targeted immunoPET imaging allows non-invasive quantification of the TROP-2 expression levels of tumors, which could help to screen beneficiaries most likely to respond to SG and predict the response. This study aimed to develop a 89Zr/177Lu-radiolabeled anti-TROP-2 antibody (NY003) for immunoPET and SPECT imaging, as well as radioimmunotherapy (RIT) in TROP-2 (+)TNBC tumor-bearing model. Based on the camelid antibody, we developed a TROP-2 targeted recombinant antibody NY003. NY003 was conjugated with DFO and DTPA for 89Zr and 177Lu radiolabelling, respectively. The theranostic potential of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 was evaluated through immunoPET, SPECT imaging, and RIT studies in the subcutaneous TROP-2 positive TNBC xenograft mice model.

RESULTS

The high binding affinity of NY003 to TROP-2 was verified through ELISA. The radiochemical purity of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 exceeded 95% and remained stable within 144h p.i. in vitro. ImmunoPET and SPECT imaging showed the specific accumulation of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003 in MDA-MB-231 tumors and gradually increased with the time tested, significantly higher than that in control groups (P < 0.05). The strongest anti-tumor efficacy was observed in the high-dose of [177Lu]Lu-DTPA-NY003 group, followed by the low-dose group, the tumor growth was significantly suppressed by [177Lu]Lu-DTPA-NY003, the tumor volumes of both high- and low-dose groups were smaller than the control groups (P < 0.05). Ex vivo biodistribution and histological staining verified the results of in vivo imaging and RIT studies.

CONCLUSION

As a drug platform for radiotheranostics, 89Zr/177Lu-radiolabeled anti-TROP-2 antibody NY003 could not only non-invasively screen the potential beneficiaries for optimizing SG ADC treatment but also suppressed the growth of TROP-2 positive TNBC tumors, strongly supporting the theranostic potential of [89Zr]Zr-DFO-NY003/[177Lu]Lu-DTPA-NY003.

Auranofin sensitizes breast cancer cells to paclitaxel chemotherapy by disturbing the cellular redox system

The intrinsic redox status of cancer cells limits the efficacy of chemotherapeutic drugs. Auranofin, a Food and Drug Administration-approved gold-containing compound, documented with effective pharmacokinetics and safety profiles in humans, has recently been repurposed for anticancer activity. This study examined the paclitaxel-sensitizing effect of auranofin by targeting redox balance in the MDA-MB-231 and MCF-7 breast cancer cell lines. Auranofin treatment depletes the activities of superoxide dismutase, catalase, and glutathione peroxidase and alters the redox ratio in the breast cancer cell lines. Furthermore, it has been noticed that auranofin augmented paclitaxel-mediated cytotoxicity in a concentration-dependent manner in both MDA-MB-231 and MCF-7 cell lines. Moreover, auranofin increased the levels of intracellular reactive oxygen species (observed using 2, 7-diacetyl dichlorofluorescein diacetate staining) and subsequently altered the mitochondrial membrane potential (rhodamine-123 staining) in a concentration-dependent manner. Further, the expression of apoptotic marker p21 was found to be higher in auranofin plus paclitaxel-treated breast cancer cells compared to paclitaxel-alone treatment. Thus, the present results illustrate the chemosensitizing property of auranofin in MDA-MB-231 and MCF-7 breast cancer cell lines via oxidative metabolism. Therefore, auranofin could be considered a chemosensitizing agent during cancer chemotherapy.

Circulating biomarkers in perioperative management of cancer patients

Owing to the advances in surgical technology, most solid tumours can be controlled by surgical excision. The priority should be tumour control, while some routine perioperative management might influence cancer progression in an unnoticed way. Moreover, it is increasingly recognized that effective perioperative management should include techniques to improve postoperative outcomes. These influences are elucidated by the different functions of circulating biomarkers in cancer patients. Here, circulating biomarkers with two types of clinical functions were reviewed: (i) circulating biomarkers for cancer progression monitoring, for instance, those related to cancer cell malignancy, tumour microenvironment formation, and early metastasis, and (ii) circulating biomarkers with relevance to postoperative outcomes, including systemic inflammation, immunosuppression, cognitive dysfunction, and pain management. This review aimed to provide new perspectives for the perioperative management of patients with cancer and highlight the potential clinical translation value of circulating biomarkers in improving outcomes.

Cancer Bioenergetics and Tumor Microenvironments-Enhancing Chemotherapeutics and Targeting Resistant Niches through Nanosystems

Cancer is an impending bottleneck in the advanced scientific workflow to achieve diagnostic, prognostic, and therapeutic success. Most cancers are refractory to conventional diagnostic and chemotherapeutics due to their limited targetability, specificity, solubility, and side effects. The inherent ability of each cancer to evolve through various genetic and epigenetic transformations and metabolic reprogramming underlies therapeutic limitations. Though tumor microenvironments (TMEs) are quite well understood in some cancers, each microenvironment differs from the other in internal perturbations and metabolic skew thereby impeding the development of appropriate diagnostics, drugs, vaccines, and therapies. Cancer associated bioenergetics modulations regulate TME, angiogenesis, immune evasion, generation of resistant niches and tumor progression, and a thorough understanding is crucial to the development of metabolic therapies. However, this remains a missing element in cancer theranostics, necessitating the development of modalities that can be adapted for targetability, diagnostics and therapeutics. In this challenging scenario, nanomaterials are modular platforms for understanding TME and achieving successful theranostics. Several nanoscale particles have been successfully researched in animal models, quite a few have reached clinical trials, and some have achieved clinical success. Nanoparticles exhibit an intrinsic capability to interact with diverse biomolecules and modulate their functions. Furthermore, nanoparticles can be functionalized with receptors, modulators, and drugs to facilitate specific targeting with reduced toxicity. This review discusses the current understanding of different theranostic nanosystems, their synthesis, functionalization, and targetability for therapeutic modulation of bioenergetics, and metabolic reprogramming of the cancer microenvironment. We highlight the potential of nanosystems for enhanced chemotherapeutic success emphasizing the questions that remain unanswered.

Comprehensive Profiling of Cancer-Associated Cells in the Blood of Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy to Predict Pathological Complete Response

Neoadjuvant chemotherapy (NAC) can affect pathological complete response (pCR) in breast cancers; the resection that follows identifies patients with residual disease who are then offered second-line therapies. Circulating tumor cells (CTCs) and cancer-associated macrophage-like cells (CAMLs) in the blood can be used as potential biomarkers for predicting pCR before resection. CTCs are of epithelial origin that undergo epithelial-to-mesenchymal transition to become more motile and invasive, thereby leading to invasive mesenchymal cells that seed in distant organs, causing metastasis. Additionally, CAMLs in the blood of cancer patients are reported to either engulf or aid the transport of cancer cells to distant organs. To study these rare cancer-associated cells, we conducted a preliminary study where we collected blood from patients treated with NAC after obtaining their written and informed consent. Blood was collected before, during, and after NAC, and Labyrinth microfluidic technology was used to isolate CTCs and CAMLs. Demographic, tumor marker, and treatment response data were collected. Non-parametric tests were used to compare pCR and non-pCR groups. Univariate and multivariate models were used where CTCs and CAMLs were analyzed for predicting pCR. Sixty-three samples from 21 patients were analyzed. The median(IQR) pre-NAC total and mesenchymal CTC count/5 mL was lower in the pCR vs. non-pCR group [1(3.5) vs. 5(5.75); p = 0.096], [0 vs. 2.5(7.5); p = 0.084], respectively. The median(IQR) post-NAC CAML count/5 mL was higher in the pCR vs. non-pCR group [15(6) vs. 6(4.5); p = 0.004]. The pCR group was more likely to have >10 CAMLs post-NAC vs. non-pCR group [7(100%) vs. 3(21.4%); p = 0.001]. In a multivariate logistic regression model predicting pCR, CAML count was positively associated with the log-odds of pCR [OR = 1.49(1.01, 2.18); p = 0.041], while CTCs showed a negative trend [Odds Ratio (OR) = 0.44(0.18, 1.06); p = 0.068]. In conclusion, increased CAMLs in circulation after treatment combined with lowered CTCs was associated with pCR.

Elevation of Cytoplasmic Calcium Suppresses Microtentacle Formation and Function in Breast Tumor Cells

Cytoskeletal remodeling in circulating tumor cells (CTCs) facilitates metastatic spread. Previous oncology studies examine sustained aberrant calcium (Ca²⁺) signaling and cytoskeletal remodeling scrutinizing long-term phenotypes such as tumorigenesis and metastasis. The significance of acute Ca²⁺ signaling in tumor cells that occur within seconds to minutes is overlooked. This study investigates rapid cytoplasmic Ca²⁺ elevation in suspended cells on actin and tubulin cytoskeletal rearrangements and the metastatic microtentacle (McTN) phenotype. The compounds Ionomycin and Thapsigargin acutely increase cytoplasmic Ca²⁺, suppressing McTNs in the metastatic breast cancer cell lines MDA-MB-231 and MDA-MB-436. Functional decreases in McTN-mediated reattachment and cell clustering during the first 24 h of treatment are not attributed to cytotoxicity. Rapid cytoplasmic Ca²⁺ elevation was correlated to Ca²⁺-induced actin cortex contraction and rearrangement via myosin light chain 2 and cofilin activity, while the inhibition of actin polymerization with Latrunculin A reversed Ca²⁺-mediated McTN suppression. Preclinical and phase 1 and 2 clinical trial data have established Thapsigargin derivatives as cytotoxic anticancer agents. The results from this study suggest an alternative molecular mechanism by which these compounds act, and proof-of-principle Ca²⁺-modulating compounds can rapidly induce morphological changes in free-floating tumor cells to reduce metastatic phenotypes.

Size-Based Method for Enrichment of Circulating Tumor Cells from Blood of Colorectal Cancer Patients

Circulating tumor cells (CTCs) are precursors of the metastatic cascade, which is responsible for 90% of all cancer-related deaths. CTCs arise from solid tumors and travel through the bloodstream and lymphatic system. Developments in the isolation and analysis of CTCs promise potential biomarker assays for detection and monitoring of cancer through a minimally invasive procedure. Despite this, the precise role of CTCs in metastasis remains poorly characterized, mainly due to the low density of CTCs (1-10 CTCs per 10 mL of blood) present in patient blood and the lack of robust methods for their isolation in a standard laboratory setting. CellSearch is currently the only FDA-approved CTC enrichment protocol, but limitations of this EpCAM-based method include cost, availability, and the use of a single surface marker for capture. To address these limitations, we have optimized an existing method, MetaCell, which exploits the differences in size of CTCs compared to other blood cells for CTC enrichment from blood. MetaCell contains a membrane with 8 μm pores, and blood is filtered through this kit by capillary action and CTCs, which are typically larger than the pores and remain on top of the membrane, while most leukocytes pass through the pores. The membrane along with these CTCs can be detached and transferred to 6-well plates for culturing or directly used for characterization. Here, we provide a detailed protocol for enrichment of CTCs using the filtration device MetaCell and a procedure for characterization of CTCs by immunohistochemical staining.

Phenotyping of rare circulating cells in the blood of non-metastatic breast cancer patients using microfluidic Labyrinth technology

Label-free technologies for isolating rare circulating cells in breast cancer patients are widely available; however, they are mostly validated on metastatic patient blood samples. Given the need to use blood-based biomarkers to inform on disease progression and treatment decisions, it is important to validate these technologies in non-metastatic patient blood samples. In this study, we specifically focus on a recently established label-free microfluidic technology Labyrinth and assess its capabilities to phenotype a variety of rare circulating tumor cells indicative of epithelial-to-mesenchymal transition as well as cancer-associated macrophage-like (CAML) cells. We specifically chose a patient cohort that is non-metastatic and selected to undergo neoadjuvant chemotherapy to assess the performance of the Labyrinth technology. We enrolled 21 treatment naïve non-metastatic breast cancer patients of various disease stages. Our results indicate that (i) Labyrinth microfluidic technology is successfully able to isolate different phenotypes of CTCs despite the counts being low. (ii) Invasive phenotypes of CTCs such as transitioning CTCs and mesenchymal CTCs were found to be present in high numbers in stage III patients as compared to stage II patients. (iii) As the total load of CTCs increased, the mesenchymal CTCs were found to be increasing. (iv) Labyrinth was able to isolate CAMLs with the counts being higher in stage III patients as compared to stage II patients. Our study demonstrates the ability of the Labyrinth microfluidic technology to isolate rare cancer-associated cells from the blood of treatment naïve non-metastatic breast cancer patients, laying the foundation for tracking oncogenic spread and immune response in patients undergoing neoadjuvant chemotherapy.

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.

Flexible Electronic Catheter Based on Nanofibers for the In Vivo Elimination of Circulating Tumor Cells

Clearing circulating tumor cells (CTCs) that are closely related to cancer metastasis and recurrence in peripheral blood helps to reduce the probability of cancer recurrence and metastasis. However, conventional therapies aiming at killing CTCs always cause damage to normal blood cells, tissues, and organs. Here, we report a flexible electronic catheter that can capture and kill CTCs via irreversible electroporation (IRE) with high efficiency. The flexible electronic catheter is assembled from nanofibers (NFs) with liquid metal-polymer conductor (MPC) electrodes. The NFs were modified with an epithelial cellular adhesion molecule (EpCAM) antibody on the surface to improve specific biorecognition and cell adhesion. Whole-body blood can be screened by the catheter repeatedly, during which the EpCAM antibody on a nanofiber can enrich CTCs to the surface of the catheter. Taking advantage of the high specific surface area, the capture efficiency of NF-based catheters for CTCs is 25 times higher than previously reported cases. Furthermore, the number of nonspecifically captured WBCs is less than 10 per mm² areas of the catheter, compared to their original large number of 4-11 × 10⁶ mL^-1 of whole blood, showing good specificity of the flexible electronic catheter. The flexible and biocompatible MPC electrodes have a high killing efficiency of 100% for the captured CTCs in a rabbit model. No noticeable hematologic index and morphological changes of the vessels and major organs were observed, indicating that this electronic catheter had good biocompatibility. The present functional electronic catheter offers an alternative strategy for improving the efficiency of clinical cancer therapy.