Eribulin Synergistically Increases Anti-Tumor Activity of an mTOR Inhibitor by Inhibiting pAKT/pS6K/pS6 in Triple Negative Breast Cancer

Clinical translation of antibody drug conjugate dosing in solid tumors from preclinical mouse data

Antibody drug conjugates (ADCs) have made impressive strides in the clinic in recent years with 11 Food and Drug Administration approvals, including 6 for the treatment of patients with solid tumors. Despite this success, the development of new agents remains challenging with a high failure rate in the clinic. Here, we show that current approved ADCs for the treatment of patients with solid tumors can all show substantial efficacy in some mouse models when administered at a similar weight-based [milligrams per kilogram (mg/kg)] dosing in mice that is tolerated in the clinic. Mechanistically, equivalent mg/kg dosing results in a similar drug concentration in the tumor and a similar tissue penetration into the tumor due to the unique delivery features of ADCs. Combined with computational approaches, which can account for the complex distribution within the tumor microenvironment, these scaling concepts may aid in the evaluation of new agents and help design therapeutics with maximum clinical efficacy.

Small molecule agents for triple negative breast cancer: Current status and future prospects

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor prognosis. The number of cases increased by 2.26 million in 2020, making it the most commonly diagnosed cancer type in the world. TNBCs lack hormone receptor (HR) and human epidermal growth factor 2 (HER2), which limits treatment options. Currently, paclitaxel-based drugs combined with other chemotherapeutics remain the main treatment for TNBC. There is currently no consensus on the best therapeutic regimen for TNBC. However, there have been successful clinical trials exploring large-molecule monoclonal antibodies, small-molecule targeted drugs, and novel antibody-drug conjugate (ADC). Although monoclonal antibodies have produced clinical success, their large molecular weight can limit therapeutic benefits. It is worth noting that in the past 30 years, the FDA has approved small molecule drugs for HER2-positive breast cancers. The lack of effective targets and the occurrence of drug resistance pose significant challenges in the treatment of TNBC. To improve the prognosis of TNBC, it is crucial to search for effective targets and to overcome drug resistance. This review examines the clinical efficacy, adverse effects, resistance mechanisms, and potential solutions of targeted small molecule drugs in both monotherapies and combination therapies. New therapeutic targets, including nuclear export protein 1 (XPO1) and hedgehog (Hh), are emerging as potential options for researchers and become integrated into clinical trials for TNBC. Additionally, there is growing interest in the potential of targeted protein degradation chimeras (PROTACs), degraders of rogue proteins, as a future therapy direction. This review provides potentially valuable insights with clinical implications.

Genetic analysis of oligo-recurrence breast cancer: correlation with clinical outcomes

BACKGROUND

We aimed to identify the relationship between the genomic characteristics and clinical outcomes of oligo-metastatic breast cancer.

METHODS

Oligo-metastatic breast cancer diagnosed by pathology from January 2001 and August 2019 were reviewed and we matched the poly-metastatic patients based on the clinicopathological features of patients included. Clinicopathological values and data of genomic alterations were collected. Oligo-recurrence (oligo-R) was defined as a situation where disease progression occurred in less than 5 anatomical sites and other anatomic areas still suppressed by the ongoing therapy.

RESULTS

A total of 26 breast cancer patients were enrolled in our study, including 14 patients with strict oligo-metastatic disease (oligo-R > 6 months) and 12 with simultaneous poly-metastatic disease. PIK3CA, TP53 and ERBB2 were the most common shared alterations identified in patients included. Based on the median time of oligo-R, we divided the patients with oligo-metastasis into longer oligo-R group (oligo-R > 31.04 months) and shorter oligo-R group (oligo-R ≤ 31.04 months). The analysis of PIK3CA mutation sites showed that H1047R mutation was closely associated with oligo-metastasis, rather than poly-metastasis. H1047R mutation also predicted a better prognosis (oligo-R > 31.04 months) in oligo-metastatic breast cancer. In addition, HER2 positive was more likely to be related to a good outcome in patients with oligo-metastasis.

CONCLUSIONS

Through the genetic analysis of samples from oligo-metastasis, we found the prognostic values of PIK3CA H1047R and HER2 in oligo- and poly-metastasis. We improved the stratification of prognosis and provided new insights for biological behaviors of oligo-metastatic breast cancer.

Determination of Rutin's antitumoral effect on EAC solid tumor by AgNOR count and PI3K/AKT/mTOR signaling pathway

Rutin is one of the flavonoids found in fruits and vegetables. The PI3K/AKT/mTOR signaling pathway is critical for the life cycle at the cellular level. In current study, we purposed to demonstrate the antitumoral effect of rutin at different doses through the mTOR-signaling pathway and argyrophilic nucleolar regulatory region. EAC cells were injected subcutaneously into the experimental groups. 25 and 50 mg/kg Rutin were injected intraperitoneally to the animals with solid tumors for 14 days. Immunohistochemical, Real-time PCR and AgNOR analyzes were actualized on the taken tumors. When the rutin given groups and the tumor group were compared, the tumor size increase was detected to be statistically significant (p < 0.05). In immunohistochemical analysis, a significant decrease was encountered in the AKT, mTOR, PI3K and F8 expressions especially in the groups administered 25 mg Rutin, in comparison with the control group (p < 0.05). AgNOR area/nuclear area (TAA/NA) and average AgNOR number were determineted, and statistically important differences were detected between the groups in terms of TAA/NA ratio (p < 0.05). There were significant statistical differences between the mRNA quantity of the PI3K, AKT1 and mTOR genes (p < 0.05). In the in vitro study, cell apoptosis was evaluated with different doses of annexin V and it was determined that a dose of 10 µg/mL Rutin induced apoptosis (p < 0.05). In our study, it was demonstrated in vivo and in vitro that Rutin has an anti-tumor effect on the development of solid tumors formed by both EAC cells.

Recent advances in therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer (BC) with a poor prognosis. Current treatment options are limited to surgery, adjuvant chemotherapy and radiotherapy; however, a proportion of patients have missed the surgical window at the time of diagnosis. TNBC is a highly heterogeneous cancer with specific mutations and aberrant activation of signaling pathways. Hence, targeted therapies, such as those targeting DNA repair pathways, androgen receptor signaling pathways, and kinases, represent promising treatment options against TNBC. In addition, immunotherapy has also been demonstrated to improve overall survival and response in TNBC. In this review, we summarize recent key advances in therapeutic strategies based on molecular subtypes in TNBC.

Overexpressed p-S6 associates with lymph node metastasis and predicts poor prognosis in non-small cell lung cancer

Background

Ribosomal protein S6 (S6), a downstream effect media of the AKT/mTOR pathway, not only is a part of 40S small subunit of eukaryotic ribosome, but also involves in protein synthesis and cell proliferation during cancer development.

Methods

In present study, we explore the association between phosphorylated S6 (p-S6) protein expression and clinicopathological features as well as prognostic implications in NSCLC. P-S6 was detected in tissue microarrays (TMAs) containing 350 NSCLC, 53 non-cancerous lung tissues (Non-CLT), and 88 cases of matched metastatic lymph node lesions via immunohistochemistry (IHC). Transwell assays and wound healing assay were used to assess the effects of p-S6 inhibition on NSCLC cell metastasis.

Results

The p-S6 expression in NSCLC was more evident than that in Non-CLT (p < 0.05). Compared to NSCLC patients who have no lymph node metastasis (LNM), those with LNM had higher p-S6 expression (p = 0.001). Regardless of lung squamous cell carcinoma (SCC) or adenocarcinoma (ADC), p-S6 was increased obviously in metastatic lymph nodes compared with matched primary cancers (p = 0.001, p = 0.022, respectively). Inhibition of p-S6 decreased the metastasis ability of NSCLC cells. In addition, p-S6 was an independent predicted marker for LNM in patients with NSCLC (p < 0.001). According to survival analysis, patients with highly expressed p-S6 had a lower survival rate compared with that with lower expression (p = 0.013). P-S6 is an unfavorable independent prognostic factor for NSCLC patients (p = 0.011).

Conclusion

Increased expression of p-S6 is not only a novel predictive biomarker of LNM but also poor prognosis in NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09664-4.

Molecular targets and therapeutics in chemoresistance of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a specific subtype of breast cancer (BC), which shows immunohistochemically negative expression of hormone receptor i.e., Estrogen receptor and Progesterone receptor along with the absence of Human Epidermal Growth Factor Receptor-2 (HER2/neu). In Indian scenario the prevalence of BC is 26.3%, whereas, in West Bengal the cases are of 18.4%. But the rate of TNBC has increased up to 31% and shows 27% of total BC. Conventional chemotherapy is effective only in the initial stages but with progression of the disease the effectivity gets reduced and shown almost no effect in later or advanced stages of TNBC. Thus, TNBC patients frequently develop resistance and metastasis, due to its peculiar triple-negative nature most of the hormonal therapies also fails. Development of chemoresistance may involve various factors, such as, TNBC heterogeneity, cancer stem cells (CSCs), signaling pathway deregulation, DNA repair mechanism, hypoxia, and other molecular factors. To overcome the challenges to treat TNBC various targets and molecules have been exploited including CSCs modulator, drug efflux transporters, hypoxic factors, apoptotic proteins, and regulatory signaling pathways. Moreover, to improve the targets and efficacy of treatments researchers are emphasizing on targeted therapy for TNBC. In this review, an effort has been made to focus on phenotypic and molecular variations in TNBC along with the role of conventional as well as newly identified pathways and strategies to overcome challenge of chemoresistance.

Clinical and preclinical features of eribulin-related peripheral neuropathy

Different microtubule-targeting agents (MTAs) possess distinct modes of action and their clinical use in cancer treatment is often limited by chemotherapy-induced peripheral neurotoxicity (CIPN). Eribulin is a member of the halichondrin class of antineoplastic drugs, which is correlated with a high antimitotic activity against metastatic breast cancer and liposarcoma. Current clinical evidence suggests that eribulin treatment, unlike some of the other MTAs, is associated with a relatively low incidence of severe peripheral neuropathy. This suggests that different MTAs possess unique mechanisms of neuropathologic induction. Animal models reliably reproduced eribulin-related neuropathy providing newer insights in CIPN pathogenesis, and they are highly suitable for in vivo functional, symptomatic and morphological characterizations of eribulin-related CIPN. The purpose of this review is to discuss the most recent literature on eribulin with a focus on both clinical and preclinical data, to explain the molecular events responsible for its favorable neurotoxic profile.

Chemoresistance in breast cancer: PI3K/Akt pathway inhibitors vs the current chemotherapy

Breast cancer is the most prevalent type of cancer among women. Several types of drugs, targeting the specific proteins expressed on the breast cancer cell surface (such as receptor tyrosine kinases and immune checkpoint regulators) and proteins involved in cell cycle and motility (including cyclin-dependent kinases, DNA stabilisers, and cytoskeleton modulators) are approved for different subtypes of breast cancer. However, breast cancer also has a poor response to conventional chemotherapy due to intrinsic and acquired resistance, and an Akt fingerprint is detectable in most drug-resistant cases. Overactivation of Akt and its upstream and downstream regulators in resistant breast cancer cells is considered a major potential target for novel anti-cancer therapies, suggesting that Akt signalling acts as a cellular mechanism against chemotherapy. The present review has shown that sustained activation of Akt results in resistance to different types of chemotherapy. Akt signalling plays a cellular defence role against chemotherapy and (1) enhances multi-drug resistance, (2) increases reactive oxygen species at breast tumor microenvironment, (3) enhances anaerobic metabolism, (4) inhibits the tricarboxylic cycle, (5) promotes PD-L1 upregulation, (6) inhibits apoptosis, (7) increases glucose uptake, and more importantly (8) recruits and interconnects the plasma membrane, nucleus, endoplasmic reticulum, and mitochondria to hijack breast cancer cells and rescue these cells from chemotherapy. Therefore, Akt signalling is considered a cellular defence mechanism employed against chemotherapeutic effects. In addition, interfering roles of PI3K/Akt signalling on the current cytotoxic and molecularly targeted therapy as well as immunotherapy of breast cancer are discussed with a clinical approach. Although, alpelisib, a PIK3CA inhibitor, is the only PI3K/Akt pathway inhibitor approved for breast cancer, we also highlight well-evaluated inhibitors of PI3K/Akt signalling based on different subtypes of breast cancer, which are under clinical trials whether as monotherapy or in combination with other types of chemotherapy.

Incorporation of eribulin in the systemic treatment of metastatic breast cancer patients in Australia

PURPOSE

Review of utilization and efficacy of eribulin in Australian metastatic breast cancer (MBC) patients.

METHODS

Retrospective review of consecutive MBC patients treated with eribulin in tertiary Australian BC centers. Key inclusion criteria included eribulin administration in nonclinical trial setting from October 2014 onwards, known duration of MBC systemic treatments administered and known follow-up date after eribulin. Cox regression model was used to assess survival.

RESULTS

Study population comprised 266 patients from eight centers treated between October 2014 and May 2018. Median age at time of MBC diagnosis was 54 years with 18% of patients having de novo MBC. Seventy-six percent had hormone receptor positive (HRp) disease, 19% triple negative (TN) and 5% HER2-positive. CNS involvement was present in 36% of patients. Eribulin was most frequently given as third-line chemotherapy (36%), with no prior anthracycline exposure in 14% of total population. Eribulin was given more frequently as ≤third-line chemotherapy than > third-line in patients with TN disease, ≥ two metastatic sites or CNS disease. Median overall survival (OS) from eribulin administration was 9.2 (95% CI [8.0, 10.3]) months.

CONCLUSION

Similar efficacy was demonstrated for eribulin when given in the first-line to beyond the fifth line of chemotherapy in all subtypes of MBC.

Research update on the anticancer effects of buparlisib

Buparlisib is a highly efficient and selective PI3K inhibitor and a member of the 2,6-dimorpholinopyrimidine-derived family of compounds. It selectively inhibits four isomers of PI3K, PI3Kα, PI3Kβ, PI3Kγ and PI3Kδ, by competitively binding the lipid kinase domain on adenosine 5'-triphosphate (ATP), and serves an important role in inhibiting proliferation, promoting apoptosis and blocking angiogenesis, predominantly by antagonizing the PI3K/AKT pathway. Buparlisib has been confirmed to have a clinical effect in patients with solid tumors and hematological malignancies. A global, phase II clinical trial with buparlisib and paclitaxel in head and neck squamous cell carcinoma has now been completed, with a manageable safety profile. Buparlisib currently has fast-track status with the United States Food and Drug Administration. The present review examined the biochemical structure, pharmacokinetic characteristics, preclinical data and ongoing clinical studies of buparlisib. The various mechanisms of influence of buparlisib in tumors, particularly in preclinical research, were summarized, providing a theoretical basis and direction for basic research on and clinical treatment with buparlisib.

mTOR Signaling in Metabolism and Cancer

The mechanistic/mammalian target of rapamycin (mTOR), a serine/threonine kinase, is a central regulator for human physiological activity. Deregulated mTOR signaling is implicated in a variety of disorders, such as cancer, obesity, diabetes, and neurodegenerative diseases. The papers published in this special issue summarize the current understanding of the mTOR pathway and its role in the regulation of tissue regeneration, regulatory T cell differentiation and function, and different types of cancer including hematologic malignancies, skin, prostate, breast, and head and neck cancer. The findings highlight that targeting the mTOR pathway is a promising strategy to fight against certain human diseases.

Synergistic Anti-Tumor Activity by Targeting Multiple Signaling Pathways in Ovarian Cancer

More effective therapy is needed to improve the survival of patients with advanced and recurrent ovarian cancer. Preclinical and early clinical studies with single molecular targeted agents have shown limited antitumor activity in ovarian cancer, likely due to compensation by alternative growth/survival pathways. An emerging strategy in overcoming resistance is to combine inhibitors targeting multiple pathways. In this study, we used a novel strategy of combining several FDA-approved targeted drugs, including sunitinib, dasatinib, and everolimus, in human ovarian cancers. Combination of the tyrosine kinase inhibitor sunitinib with the SRC inhibitor dasatinib showed synergistic anti-tumor activity in human ovarian cancer cells. The increased activity was associated with inhibition of the STAT3, SRC, and MAPK signaling pathways, but not AKT signaling. To inhibit the PI3K/AKT/mTOR pathway, we added the mTOR inhibitor everolimus, which further increased anti-tumor activity in cells. Combined treatment with sunitinib, dasatinib, and everolimus also resulted in greater inhibition of human ovarian tumor growth in mice. Furthermore, the triple combination also synergistically increased the anti-tumor activity of paclitaxel, both in vitro and in vivo. Taken together, our results demonstrate that simultaneous inhibition of several signaling pathways results in better anti-tumor activity compared to inhibiting any of these signaling pathways alone.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.

CCT020312 Inhibits Triple-Negative Breast Cancer Through PERK Pathway-Mediated G1 Phase Cell Cycle Arrest and Apoptosis

Triple-negative breast cancer (TNBC) has a poor prognosis due to the lack of specific therapeutic targets. CCT020312, a selective eukaryotic translation initiation factor 2 alpha (eIF2α)/protein kinase RNA-like endoplasmic reticulum kinase (PERK) activator, may have a potent anti-tumor effect. In the present study, we examined the effects of CCT020312 on TNBC and explored the underlying mechanism. We found that CCT020312 inhibited the viability of TNBC cell lines, MDA-MB-453 and CAL-148, by inducing apoptosis and G1 phase cell cycle arrest. CCT020312 decreased the protein levels of cyclin-dependent kinase 4 (CDK4), CDK6, cyclin D1, and B-cell lymphoma 2 (Bcl-2) and increased the levels of Bcl-2-associated X protein (Bax) and cleaved poly (ADP-ribose) polymerase (PARP) compared with those in the control. CCT020312 activated PERK/eIF2α/activating transcription factor 4 (ATF4)/CCAAT-enhancer binding protein (C/EBP) homologous protein transcription factor (CHOP) signaling and inhibited protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling. Furthermore, CCT020312 inhibited tumor growth in an MDA-MB-453 orthotopic xenograft mouse model by activating the PERK/eIF2α/ATF4/CHOP pathway and inhibiting the AKT/mTOR pathway. Thus, our study shows that CCT020312 may be a potential drug candidate for TNBC treatment.

Saikosaponin A Inhibits Triple-Negative Breast Cancer Growth and Metastasis Through Downregulation of CXCR4

Purpose: Due to a lack of recognized molecular targets for therapy, patients with triple-negative breast cancer (TNBC), unlike other subtypes of breast cancers, generally have not benefited from the advances made with targeted agents. The CXCR4/SDF-1 axis is involved in tumor growth and metastasis of TNBC. Therefore, down-regulation of the expression of CXCR4 in cancer cells is a potential therapeutic strategy for inhibiting primary tumor growth and metastasis of TNBC. In order to identify bioactive compounds that inhibit the expression of CXCR4 in traditional Chinese medicines, we investigated the capacity of saikosaponin A (SSA), one of the active ingredients isolated from Radix bupleuri, to affect CXCR4 expression and function in TNBC cells. Methods: Analyses of cell growth, migration, invasion, and protein expression were performed. Knockdowns by small interfering RNA (siRNA) and non-invasive bioluminescence were also used. Results: SSA reduced proliferation and colony formation of SUM149 and MDA-MB-231 cells. SSA inhibited migration and invasion of TNBC cells. For mice, SSA inhibited primary tumor growth and reduced lung metastasis of highly metastatic, triple-negative 4T1-luc cells. SSA inhibited CXCR4 expression but did not regulate CXCR7 expression in vitro and in vivo. The inhibitory effects on the migration and invasion of TNBC cells were reversed by down-regulation of CXCR4 expression. In addition, SSA inactivated the Akt/mTOR signaling pathway and inhibited MMP-9 and MMP-2 expression. Conclusions: The results show that SSA exerts an anti-TNBC effect through the inhibition of CXCR4 expression and thus has the potential to be a candidate therapeutic agent for TNBC patients.

Novel therapeutic avenues in triple-negative breast cancer: PI3K/AKT inhibition, androgen receptor blockade, and beyond

Multiomic analyses have shed light upon the molecular heterogeneity and complexity of triple-negative breast cancers (TNBCs). With increasing recognition that TNBC is not a single disease entity but encompasses different disease subtypes, a one-size-fits-all treatment paradigm has become obsolete. In this context, the inhibition of phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) and androgen receptor (AR) signaling pathways have emerged as potential therapeutic strategies against selected tumors. In this paper, we reviewed the preclinical rationale, predictive biomarkers, efficacy, and safety data from early phase trials, and the future directions for these two biomarker-directed treatment approaches in TNBC.