Spectrum of PIK3CA/AKT mutations across molecular subtypes of triple-negative breast cancer

Next-Generation Sequencing-Based Analysis of Clinical and Pathological Features of PIK3CA-Mutated Breast Cancer

Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) is a well-known oncogene with a high prevalence of mutation in breast cancer patients. The effect of the mutation is a deregulation in phosphatidylinositol 3-kinase-related pathways, and, consequently, in unrestricted cell growth and differentiation. With the advent of precision oncology, PIK3CA has emerged as a pivotal treatment target, culminating in the recent approval of alpelisib. Despite years of research on this genetic alteration, certain aspects of its influence on the prognosis of breast cancer remain ambiguous. The purpose of this analysis is to characterize the clinical picture of breast cancer patients with PIK3CA mutation in comparison to the PIK3CA-wild-type group. We examined 103 tumor samples from 100 breast cancer patients using a next-generation sequencing panel. Presence of the mutation was linked to an older age at diagnosis, a lower expression of Ki67 protein, a greater percentage of tumors expressing progesterone receptors, and a notably higher incidence of metastatic disease at presentation. No significant differences were identified in overall and progression-free survival between the two groups. Our findings enhance the understanding of how PIK3CA mutations shape the clinical and prognostic landscape for breast cancer patients.

Paclitaxel-loaded tumor cell-derived microparticles improve radiotherapy efficacy in triple-negative breast cancer by enhancing cell killing and stimulating immunity

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor characterized by high recurrence and metastasis, with a very poor prognosis, and there are still great challenges in its clinical treatment. Here, we describe the development of a novel modality for the treatment of TNBC with tumor cell-derived microparticles loaded with paclitaxel (MP-PTX) in combination with radiotherapy. We show that MP can deliver agents to tumor cells by homologous targeting, thereby increasing the absorption rate of the chemotherapeutic agent and enhancing its killing effects on tumor cells. We further demonstrate that MP-PTX combined with radiotherapy shows a synergistic antitumor effect by enhancing the inhibition of tumor cell proliferation, promoting tumor cell apoptosis, reducing the immunosuppressive microenvironment at the tumor site, and activating the antitumor immune response. Altogether, this study provides a referable and optional method for the clinical treatment of refractory tumors such as TNBC based on the combination of T-MP-delivered chemotherapeutic drugs and radiotherapy. Chemical compounds: paclitaxel (PTX), paclitaxel-loaded tumor cell-derived microparticles (MP-PTX).

Luminal androgen receptor (LAR) subtype of triple-negative breast cancer: molecular, morphological, and clinical features

According to the classification presented by Lehmann BD (2016), triple-negative breast cancer (TNBC) is a heterogeneous group of malignant tumors with four specific subtypes: basal-like (subtype 1 and subtype 2), mesenchymal, and luminal androgen receptor (LAR) subtypes. The basal-like subtypes of carcinomas predominate in this group, accounting for up to 80% of all cases. Despite the significantly lower proportions of mesenchymal and LAR variants in the group of breast carcinomas with a TNBC profile, such tumors are characterized by aggressive biological behavior. To this end, the LAR subtype is of particular interest, since the literature on such tumors presents different and even contradictory data concerning the disease course and prognosis. This review is devoted to the analysis of the relevant literature, reflecting the main results of studies on the molecular properties and clinical features of the disease course of LAR-type TNBC carcinomas.

In vitro effect of PIK3CA/mTOR inhibition in triple-negative breast cancer subtype cell lines

BACKGROUND

Agents targeting the PI3K pathway in triple negative breast cancer did not show any significant efficacy so far mostly because of the complex nature of these targeted inhibitors. Targeting the cancer cells with the combination of inhibitors may help in decelerating the regulatory pathways further achieving optimum clinical benefit. In this study, we investigated the effect of PIK3CA and mTOR inhibition in-vitro in triple-negative breast cancer (TNBC) cell lines.

OBJECTIVE AND METHODS

Three TNBC cell lines; MDA MB231, MDA MB468, and MDA MB453 were subtyped using immunohistochemistry and were screened for hotspot mutations in PIK3CA and AKT1. All cell lines were treated with different concentrations of inhibitors; PI3K inhibitor (BKM 120), mTOR inhibitor (AZD 8055), and dual PI3K/mTOR inhibitor (BEZ 235), and cell viability was assessed by MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide), Trypan blue and Annexin-V/PI Assays.

RESULTS

Using immunohistochemistry, TNBC cell lines were subtyped as; mesenchymal subtype-specific cell line (MDA MB231), basal subtype-specific cell line (MDA MD468), and Luminal androgen receptor (LAR) subtype-specific cell line (MDA MB453). PIK3CA hot spot mutation (p.H1047R) in exon 20 was identified in the Luminal androgen receptor subtype (MDA MB453 cells) cell line. Cell viability assays showed that the Mesenchymal subtype-specific cell line (MDA MB231) was the most resistant to all inhibitors and the Luminal Androgen subtype (MDA MB453 cells) cell line was more sensitive to BKM120 (PI3K inhibitor) inhibition compared to other subtypes.

CONCLUSIONS

This study identified that the Luminal androgen receptor subtype of triple-negative breast cancer with PIK3CA mutation may be targeted with PIK3CA inhibitors with a favorable outcome.

Oral vinorelbine and capecitabine as first-line therapy in metastatic breast cancer: a retrospective analysis

A retrospective analysis of 70 patients with triple-negative or hormone-resistant advanced breast carcinoma who had not previously received chemotherapy was carried out. Patients received oral vinorelbine 60 mg/m² on day 1 and 8, plus capecitabine 1000 mg/m² bid for 14 consecutive days every 3 weeks. Overall response rate was 53% with a 9% complete response rate. Stable disease was recorded in 27% of the cases. Median progression-free survival was 7.9 months and median overall survival was 29.2 months. Toxicity was generally mild and easily manageable. These data demonstrate that this combination is feasible, safe and active as first-line treatment of triple-negative fully hormone-resistant advanced breast carcinoma patients.

The adoption of metronomic chemotherapy in the treatment of breast cancer is an important step forward in the management of this disease. The fluoropyrimidine capecitabine and the vinca alkaloid vinorelbine have been shown to be at least as active. Our data confirm the activity and safety of this all-oral regimen as first-line metronomic therapy being response rate.

Crosstalk between circRNAs and the PI3K/AKT signaling pathway in cancer progression

Circular RNAs (circRNAs), covalently closed noncoding RNAs, are widely expressed in eukaryotes and viruses. They can function by regulating target gene expression, linear RNA transcription and protein generation. The phosphoinositide 3-kinase (PI3K)/AKT signaling pathway plays key roles in many biological and cellular processes, such as cell proliferation, growth, invasion, migration, and angiogenesis. It also plays a pivotal role in cancer progression. Emerging data suggest that the circRNA/PI3K/AKT axis modulates the expression of cancer-associated genes and thus regulates tumor progression. Aberrant regulation of the expression of circRNAs in the circRNA/PI3K/AKT axis is significantly associated with clinicopathological characteristics and plays an important role in the regulation of biological functions. In this review, we summarized the expression and biological functions of PI3K-AKT-related circRNAs in vitro and in vivo and assessed their associations with clinicopathological characteristics. We also further discussed the important role of circRNAs in the diagnosis, prognostication, and treatment of cancers.

Targeting Akt in cancer for precision therapy

Biomarkers-guided precision therapeutics has revolutionized the clinical development and administration of molecular-targeted anticancer agents. Tailored precision cancer therapy exhibits better response rate compared to unselective treatment. Protein kinases have critical roles in cell signaling, metabolism, proliferation, survival and migration. Aberrant activation of protein kinases is critical for tumor growth and progression. Hence, protein kinases are key targets for molecular targeted cancer therapy. The serine/threonine kinase Akt is frequently activated in various types of cancer. Activation of Akt promotes tumor progression and drug resistance. Since the first Akt inhibitor was reported in 2000, many Akt inhibitors have been developed and evaluated in either early or late stage of clinical trials, which take advantage of liquid biopsy and genomic or molecular profiling to realize personalized cancer therapy. Two inhibitors, capivasertib and ipatasertib, are being tested in phase III clinical trials for cancer therapy. Here, we highlight recent progress of Akt signaling pathway, review the up-to-date data from clinical studies of Akt inhibitors and discuss the potential biomarkers that may help personalized treatment of cancer with Akt inhibitors. In addition, we also discuss how Akt may confer the vulnerability of cancer cells to some kinds of anticancer agents.