PI3K/AKT/mTOR signaling pathway: an important driver and therapeutic target in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. It has higher aggressiveness and metastasis than other subtypes, with limited effective therapeutic strategies, leading to a poor prognosis. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway is prevalently over-activated in human cancers and contributes to breast cancer (BC) growth, survival, proliferation, and angiogenesis, which could be an interesting therapeutic target. This review summarizes the PI3K/AKT/mTOR signaling pathway activation mechanism in TNBC and discusses the relationship between its activation and various TNBC subtypes. We also report the latest clinical studies on kinase inhibitors related to this pathway for treating TNBC. Our review discusses the issues that need to be addressed in the clinical application of these inhibitors.

Characterizing the Efficacy and Safety of Chemotherapy Plus Everolimus in HER2-Negative Metastatic Breast Cancer Harboring Altered PI3K/AKT/mTOR.

BACKGROUND: The clinical outcomes of chemotherapy (CT) for the treatment of metastatic triple-negative (TN) and hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC) have proven to be disappointing. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway, a tumor-promoting signaling cascade frequently mutated in breast cancer (BC), has been implicated in chemoresistance. In this study, our objective is to investigate the efficacy and safety of combining everolimus with chemotherapy in mBC patients exhibiting mutations in the PI3K/AKT/mTOR pathway. METHODS: We conducted a retrospective analysis to characterize the efficacy, safety, and their association with clinical and molecular characteristics of metastatic lesions in 14 patients with HER2- mBC. These patients harbored at least one altered member of the PI3K/AKT/mTOR signaling pathway and were treated with a combination of a chemotherapy agent and the mTOR inhibitor everolimus (CT+EVE). RESULTS: The majority of patients belonged to the triple-negative (TN) subtype (9/14, 64.3%), having already undergone 2 lines of chemotherapy (CT) in the metastatic setting (11, 78.6%). These patients carried altered phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and were administered a vinorelbine-containing regimen (10, 71.4%). The objective response rate (ORR) was 42.9%, with a disease control rate of 92.9%. The median progression-free survival (PFS) and overall survival (OS) were 5.9 (95% confidence interval (CI): 4.9-13.6) months and 14.3 (95% CI: 8.5-not reached (NR)) months, respectively. Patients with fewer prior treatment lines tended to exhibit longer PFS. OS, PFS, and ORR were comparable between hormone receptor-positive (HR+) and triple-negative breast cancer (TNBC) patients, but numerical improvements were noted in patients with a single PI3K pathway alteration compared to those with more than one alteration. Genomic alterations that surfaced upon progression on CT+EVE included cyclin dependent kinase 4 (CDK4) and epidermal growth factor receptor (EGFR) amplification, as well as neurofibromin 1 (NF1) mutation, suggesting potential mechanisms of acquired resistance. An analysis of adverse events indicated manageable toxicities. CONCLUSIONS: The findings of this study suggest both activity and safety for the combination of chemotherapy and the mTOR inhibitor everolimus (CT+EVE) in patients with HER2- mBC who have alterations in the PI3K pathway, particularly those who have received fewer prior chemotherapy. However, it is crucial to note that large-scale, randomized control studies are warranted to more comprehensively characterize the efficacy and safety of this combination therapy.

Cardiac Safety in Breast Cancer Patients Receiving Pegylated Liposome Doxorubicin Sequential Anti-HER2 Monoclonal Antibody Therapy.

Background: Cardiotoxicity associated with the sequential use of anthracyclines followed by trastuzumab is common in adjuvant therapy of patients with HER2-positive early breast cancer (eBC). However, the cardiac safety of trastuzumab concurrent with pegylated liposomal doxorubicin (PLD) is relatively less studied. Method: Clinical data of patients with HER2-positive eBC treated with PLD and cyclophosphamide (PLD-C) followed by taxanes plus trastuzumab ± pertuzumab (TH or TPH) who then completed standard anti-HER2 treatment for 12 months from June 2012 to August 2021 were retrospectively collected. The primary endpoints were clinical and subclinical cardiotoxicity. Result: In total, 70 eligible patients were enrolled. Among them, 55 patients (78.6%) received PLD-C → TH and 15 patients (21.4%) received PLD-C → TPH. The median follow-up time was 41.8 months. Until August 2021, only two patients had recurrent or metastatic diseases, with 2-year and 5-year disease-free survivals of 98.6% and 96.8%, respectively. Clinical cardiotoxicity occurred in six patients (8.6%), and all of them had an absolute decline of ≥16% from baseline left ventricular ejection fraction (LVEF) but not below the lower limit of normal (LLN = 50%). Subclinical cardiotoxicity events occurred in 17 patients (24.3%), and all of them had absolute declines of ≥10% and <16% from baseline LVEF but not below the LLN. No patients were interrupted from treatment, and all patients completed anti-HER2 treatment for 12 months. The sharpest decrease in LVEF was observed at 18 months after the start of PLD treatment. The cumulative incidences of clinical and subclinical cardiotoxicity were 9.8% and 28.3%, respectively. In the univariate analysis, body mass index, age, left chest wall radiotherapy, and ongoing cardiovascular risk factors were not significantly associated with clinical or subclinical cardiotoxicity (p > 0.05). No patients had congestive heart failure or death caused by PLD or anti-HER2 treatment. Conclusion: The sequential use of PLD and trastuzumab showed a lower incidence of clinical cardiotoxicity, presented as asymptomatic decreased LVEF, compared with the results obtained in previous clinical studies using conventional anthracycline, taxanes and trastuzumab. The study regimen demonstrated good cardiac tolerance and is an alternative strategy for cardioprotection in patients with HER2-positive eBC.

PADI4 promotes epithelial-mesenchymal transition(EMT) in gastric cancer via the upregulation of interleukin 8.

BACKGROUND: Gastric cancer (GC) is one of the deadliest tumours due to its ability to metastasize. The Epithelial-to-mesenchymal transition plays a crucial role in promoting the GC metastasis, which increases the migration and metastasis of tumour cells. Peptidyl arginine deiminase IV (PADI4) is a susceptibility gene for gastric carcinoma. The aim of this study was to evaluate the functional roles of PADI4 in gastric cancer. METHODS: The expression of PADI4 was examined by qRT-PCR, western blot and immunohistochemistry. In addition, the functional roles of PADI4 were explored by over-expression PADI4 plasmids in gastric cancer cells. RESULTS: We found that the expression of PADI4 was up-regulated in GC. PADI4 overexpression in GC cells increased the proliferation, migration, metastasis, clone forming ability, and tumorigenic ability, but reduced the apoptosis ability. The Multi-Analyte ELISArray Kit results showed that interleukin 8 (IL-8) is upregulated in PADI4-overexpressing gastric cells. Using short interfering RNA (siRNA) to silence the expression of IL-8, we demonstrated that IL-8 silencing significantly inhibited the increased migratory capacity in PADI4-overexpressing GC cells. CONCLUSIONS: Our data suggest that PADI4 accelerate metastasis by promoting IL-8 expression in gastric cancer cells, indicating that it is a new PADI4/IL-8 signalling pathway in metastatic GC.

Combined everolimus and endocrine therapy in advanced HR-positive, HER2-negative Chinese breast cancer patients: a retrospective study.

BACKGROUND: Everolimus (EVE) is an inhibitor of the mammalian target of rapamycin (mTOR) pathway, and it is approved for the treatment of advanced breast cancer (ABC). However, there is still little real-world data on using EVE in Chinese breast cancer patients. We retrospectively analyzed real-world data to determine the factors affecting EVE treatment efficacy and patient outcomes. METHODS: We retrospectively collected the treatment information of ABC patients treated with EVE from 2013 to 2020 in Zhejiang Cancer Hospital. Kaplan-Meier analysis and Cox regression methods were used to calculate and compare the progression-free survival (PFS), and identify the factors associated with EVE treatment efficacy. RESULTS: The study finally enrolled 84 patients meeting the requirement; the median PFS in all 84 patients was 6.87 months. Multivariate analysis showed that liver metastasis [hazard ratio, 1.69; 95% confidence interval (CI), 1.00-2.84; P=0.049], and brain metastasis (hazard ratio, 2.65; 95% CI, 1.07-6.58; P=0.036) were independent risk factors. Subgroup analyses demonstrated EVE + fulvestrant (FUL) was not superior to EVE + aromatase inhibitors (AIs) for PFS (5.77 vs. 7.97 months, P=0.0735). Furthermore, it showed EVE + AI was superior to EVE + FUL in some subgroups: postmenopausal group (hazard ratio, 0.50; 95% CI, 0.26-0.98); without bone metastasis group (hazard ratio, 0.22; 95% CI, 0.06-0.80); visceral disease group (hazard ratio, 0.37; 95% CI, 0.20-0.69). CONCLUSIONS: EVE combined with endocrine therapy is an effective treatment option for Chinese patients with hormone-receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) breast cancer, although EVE + FUL was not superior to EVE + AI. Liver metastasis and brain metastasis were independent risk factors for successful EVE + endocrine therapy.

Efficacy of fulvestrant 500 mg in Chinese postmenopausal women with advanced/recurrent breast cancer and factors associated with prolonged time-to-treatment failure: A retrospective case series.

This study was to investigate the efficacy and safety of fulvestrant 500 mg for the treatment of hormone receptor positive advanced postmenopausal women, including ovarian ablation and investigated factors associated with prolonged time-to-treatment failure.Data from 60 women with metastatic breast cancer who were treated at Zhejiang Cancer Hospital. Patients received 500 mg (n = 60) between December 2011 and November 2012 were followed until November 2017. Main outcomes were clinical responses to fulvestrant, including best response, progressive disease, partial response, and stable disease lasting 12 months or more. Time to progression and time to progression-free-survival were also analyzed.Among the included 60 patients (mean age 47.18 years), 51 (85.0%) had received prior adjuvant therapy. During follow-up after fulvestrant treatment, the median PFS for the best response was derived as 7.0 months (inter-quartile = 4, 13.8 months). The observed median progression-free-survival time for best response was represented longer when fulvestrant was first-line treatment than when patients received prior endocrine and/or chemotherapy. Univariate analysis revealed that receiving either endocrine therapy only or endocrine therapy plus chemotherapy prior to fulvestrant treatment may be associated with median progression-free survival time to best response (P = .002, .026, .007, respectively).Fulvestrant treatment is safe and well-tolerated in women with hormone-sensitive advanced breast cancer, and first-line fulvestrant therapy increases progression-free-survival time, especially in patients without prior adjuvant treatment.

Comprehensive mutation detection of BRCA1/2 genes reveals large genomic rearrangements contribute to hereditary breast and ovarian cancer in Chinese women.

BACKGROUND: Mutated BRCA1/2 genes are associated with hereditary breast and ovarian cancer (HBOC). So far most of the identified BRCA1/2 pathogenic variants are single nucleotide variants (SNVs) or insertions/deletions (Indels). However, large genomic rearrangements (LGRs) such as copy number variants (CNVs) are also playing an important role in HBOC predisposition. Their frequency and spectrum have been well studied in western populations but remain largely unknown for Chinese population. METHODS: Peripheral blood samples were collected from 218 unrelated familial breast and/or ovarian cancer (FBOC) patients living in Eastern China. PCR-based Sanger sequencing and panel-based next-generation sequencing (NGS) were performed to detect pathogenic SNVs and Indels in BRCA1/2 genes. For the patients lacking small pathogenic variants, multiplex ligation dependent probe amplification (MLPA) assay was conducted to screen for LGRs. RESULTS: In total, we identified 44 samples (20.1%) carrying small pathogenic variants (26 in BRCA1 and 18 in BRCA2, respectively). Among the rest of 174 samples, five were found carrying novel deleterious LGRs in BRCA1 which are exon5-7dup (1 patient), exon13-14dup (2 patients), and exon1-22del (2 patients). No LGR was found in BRCA2. Overall, LGRs accounted for 16.1% (5/31) of BRCA1 pathogenic variants, and were detected in 2.3% (5/218) of all FBOC patients. , CONCLUSIONS: LGR variants in BRCA1 gene play a significant role in Chinese HBOC patients. MLPA or other similar LGR-detecting methods should be recommended along with nucleotide sequencing as the initial screening approach for Chinese HBOC women.

A significant response to a combination of trastuzumab and vinorelbine in HER2-negative metastatic breast cancer with HER2 V777L mutation.

Metastatic breast cancer (MBC) is the most life-threatening disease in women worldwide. HER2-mutated breast carcinoma has been reported to benefit from HER2-targeted tyrosine kinase inhibitors recently. Here, we presented a heavy pretreated and harbored HER2 V777L mutation de novo stage IV Luminal B (HER2 unamplified) breast cancer patient who achieved an unexpected good response to trastuzumab combined with vinorelbine therapy. Although HER2-unamplified MBC patients do not regularly benefit from anti-HER2 target therapy, HER2 V777L mutation detected by next-generation sequencing from ctDNA may present as a predictive biomarker for anti-HER2-based strategy therapy in HER2-negative MBC patients.

Inhibitor Response to HER2 G776(YVMA) In-frame Insertion in HER2-positive Breast Cancer.

Human epidermal growth factor receptor 2 (HER2/neu or HER2) has long been recognized as an attractive therapeutic target for breast cancer. The YVMA in-frame insertion at the residue G776 (G776(YVMA)) of HER2 kinase domain is a frequently observed mutation that can largely shift drug sensitivity in targeted therapy of HER2-positive breast cancer. Here, the molecular mechanism and biological significance of tyrosine kinase inhibitor (TKI) response to HER2 G776(YVMA) insertion were investigated in detail. An established protocol that integrated bioinformatics modeling and kinase inhibition assay was employed to examine the structural basis, energetic property, and biological implication underlying the intermolecular interaction between HER2 kinase domain and three representative TKIs, i.e. two FDA-approved drugs lapatinib and gefitinib as well as a pan-kinase inhibitor staurosporine. It was found that the insertion mutation can moderately sensitize lapatinib, but cannot influence the inhibitory capability of staurosporine essentially, suggesting that the two inhibitors exhibit differentiated selectivity between the wild-type HER2 (HER2(WT)) and HER2 G776(YVMA) (HER2(YVMA)) variant. In addition, the gefitinib, which was originally developed as EGFR inhibitor, only possesses modest potency against its noncogate target HER2(WT), and the insertion can further impair the potency, causing a strong resistance for the agent to HER2(YVMA) variant.

The role of peptidylarginine deiminase 4 in ovarian cancer cell tumorigenesis and invasion.

Peptidylarginine deiminase 4 (PADI4) is an enzyme that converts both histone arginine and mono-methyl arginine residues to citrulline, and it has been detected in various subtypes of ovarian cancer. However, the mechanism of action of PADI4 in ovarian carcinogenesis remains unknown. To examine the function of PADI4, we transfected two ovarian cancer cell lines, wild-type p53 A2780 and p53-null SKOV3, with PADI4-siRNA and negative control siRNA. The proliferation of both A2780 and SKOV3 cells decreased significantly following PADI4-siRNA treatment (P A2780 < 0.01; P SKOV3 < 0.001). The invasion and migration ability of A2780 cells also significantly decreased in response to PADI4-siRNA treatment (P < 0.001), but SKOV3 cells showed no such decrease. The apoptotic rate of A2780 cells increased in the presence of PADI4-siRNA, but there was no such increase in SKOV3 cells (P > 0.05). PCR arrays of A2780 cells treated with PADI4-siRNA revealed the up-regulated expression of six genes, including cell death-inducing DFFA-like effector a (CIDEA) and tumor necrosis factor receptor superfamily member 9 (TNFRSF9), and the down-regulation of seven genes, including integrin beta 3 (ITGB3) and BCL2-antagonist/killer 1 (BAK1). These results suggest an important role for PADI4 in the p53 pathway and the regulation of the proliferation, apoptosis, invasion and migration of ovarian cancer cells. Our study also demonstrated that PADI4 contributes to tumor metastasis by regulating the gene expression of insulin-like growth factor 1 (IGF1) and WAS/WASL-interacting protein family member 1 (WIPF1).

Overexpression of ILK1 in breast cancer associates with poor prognosis.

Integrin-linked kinase 1 (ILK1), a member of the serine/threonine kinases, has been demonstrated to be associated with numerous biological and pathological processes. However, the role of ILK1 in breast cancer has not been thoroughly elucidated. The purpose of this study was to assess ILK1 expression and to explore its contribution to breast cancer. The ILK1 mRNA expression was measured by real-time quantitative reverse transcriptase-polymerase chain reaction. In addition, ILK1 expression was analyzed by immunohistochemistry in 163 clinicopathologically characterized breast cancer cases. The relationship between ILK1 expression and clinicopathological features was analyzed by appropriate statistics. Kaplan-Meier analysis and Cox proportional hazard regression models were used to investigate the correlation between ILK1 expression and prognosis of breast cancer patients. The relative mRNA expression of ILK1 was significantly higher in breast cancer tissues than in adjacent noncancerous tissues (P < 0.001). In addition, ILK1 expression was significantly correlated with tumor size (P = 0.016), grade (P = 0.024), stage (P = 0.029), lymph node metastases (P = 0.007), and estrogen receptor status (P = 0.002). Kaplan-Meier analysis indicated that patients with high ILK1 expression had poor overall survival (P < 0.001). Multivariate analysis showed that high ILK1 expression was an independent predictor of overall survival. In conclusion, our data suggest for the first time that the increased expression of ILK1 in breast cancer is associated significantly with aggressive progression and poor prognosis. ILK1 may be an important molecular marker for predicting the carcinogenesis, progression, and prognosis of breast cancer.