PIK3CA Mutation as Potential Poor Prognostic Marker in Asian Female Breast Cancer Patients Who Received Adjuvant Chemotherapy

Background: The prognostic relevance of the PIK3CA mutation together with PD-L1, c-Met, and mismatch repair deficiency (dMMR) have not been fully investigated in Asian women with breast cancer (BC) who have undergone postoperative adjuvant chemotherapy. Methods: We analyzed PIK3CA mutations via peptide nucleic acid (PNA)-mediated real-time PCR assay, PD-L1/c-Met expression via immunohistochemistry (IHC), and microsatellite instability (MSI) status using PCR and IHC, in 191 resected BCs from 2008 to 2011. The Cancer Genome Atlas (TCGA) dataset for the involvement of the PIK3CA mutation with PD-L1/c-Met/MMR was explored. Results: The PNA clamp-mediated assay was able to detect the PIK3CA mutation in 1% of the mutant population in the cell line validation. Using this method, the PIK3CA mutation was found in 78 (49.4%) of 158 samples. c-Met and PD-L1 positivity were identified in 31.4 and 21.8% of samples, respectively, which commonly correlated with high histologic grade and triple-negative subtype. MSI/dMMR was observed in 8.4% of patients, with inconsistency between MMR IHC and the MSI PCR. The PIK3CA mutation exhibited a poor prognostic association regarding recurrence-free survival (RFS) in both overall and triple-negative BCs. In subgroup analyses, the PIK3CA-mutated tumors showed poorer RFS than the PIK3CA-wildtype within the c-Met-positive, MSS, triple-negative, or age onset <50 years subgroups, which showed a similar trend of association in TCGA data. Conclusions: PIK3CA mutation together with c-Met or dMMR/MSI status might be relevant to poor prognosis in BC subsets, especially in Asian women.

HS‑146, a novel phosphoinositide 3‑kinase α inhibitor, induces the apoptosis and inhibits the metastatic ability of human breast cancer cells

The phosphoinositide 3‑kinase (PI3K) signaling pathway plays an important role in human cancer as it regulates critical cellular functions, such as survival, proliferation and metabolism. In the present study, a novel PI3Kα inhibitor (HS‑146) was synthesized and its anticancer effects on MCF‑7, MDA‑MB‑231, SKBR3 and BT‑474 human breast cancer cell lines were confirmed. HS‑146 was found to be most effective in inhibiting the proliferation of MCF‑7 cells and in inducing cell cycle arrest in the G0/G1 phase by downregulating cyclin D1, cyclin E, cyclin‑dependent kinase (Cdk)2 and Cdk4, and upregulating p21Waf1/Cip1 protein levels in this cell line. The induction of apoptosis by HS‑146 was confirmed by DAPI staining and western blot analysis. Cell shrinkage and nuclear condensation, which are typical morphological markers of apoptosis, were increased by HS‑146 in the MCF‑7 cells in a concentration‑dependent manner, and HS‑146 also increased the protein expression levels of cleaved poly(ADP‑ribose) polymerase (PARP) and decreased the protein expression levels of Mcl‑1 and caspase‑7. In addition, HS‑146 effectively decreased the phosphorylation levels of downstream PI3K effectors, such as Akt, mammalian target of rapamycin (mTOR), glycogen synthase kinase 3β (GSK3β), p70S6K1 and eukaryotic translation initiation factor 4E‑binding protein 1 (4E‑BP1). Hypoxia‑inducible factor (HIF)‑1α and vascular endothelial growth factor (VEGF) expression were also suppressed by HS‑146 under hypoxic conditions, and HS‑146 inhibited the migration and invasion of MCF‑7 cells in a concentration‑dependent manner. On the whole, the findings of the present study suggest that HS‑146, a novel PI3Kα inhibitor, may be an effective novel therapeutic candidate that suppresses breast cancer proliferation and metastasis by inhibiting the PI3K/Akt/mTOR pathway.

PIK3CA H1047R Mutation Associated with a Lower Pathological Complete Response Rate in Triple-Negative Breast Cancer Patients Treated with Anthracycline-Taxane-Based Neoadjuvant Chemotherapy

PURPOSE

PIK3CA, encoding for subunit p110a of phosphatidylinositol 3 kinase, is frequently mutated in breast cancer. PIK3CA mutation was predictive for pathological complete response (pCR) in human epidermal growth factor 2 positive breast cancer. This study explores the association of PIK3CA mutation and pCR in triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy.

Materials and Methods

A total of 92 patients with TNBC derived from a prospectively randomized phase II trial GeparSixto study (NCT01426880). Exon 9 and exon 20 of PIK3CA mutations were evaluated by using classical Sanger method with formalin-fixed paraffin-embedded tumor tissues.

RESULTS

Seven of 90 tumors (7.8%) were detectable with a PIK3CA H1047R mutation. Overall, PIK3CA H1047R mutation was significantly associated with a lower pCR rate (14.3% vs. 56.6%; odds ratio, 0.128; 95% confidence interval [CI], 0.015 to 1.108; p=0.047). In carboplatin- containing treatment patients, H1047R mutation trended to predict a lower pCR rate (20% vs. 62.5%; p=0.146). In a multivariable analysis, H1047R mutation trended to predict a lower pCR rate (hazard ratio, 0.1; 95% CI, 0.01 to 1; p=0.056).

CONCLUSION

TNBC with a PIK3CA H1047R mutation was less likely to achieve pCR after anthracycline-based neoadjuvant chemotherapy. Development of H1047R mutant selective inhibitors might be helpful to conquer this subtype of breast cancer.

HER2-positive breast cancer is lost in translation: time for patient-centered research

No biomarker beyond HER2 itself, which suffers from a low positive predictive value, has demonstrated clinical utility in breast cancer, despite numerous attempts to improve treatment tailoring for the growing number of anti-HER2 targeted therapies. This prompted us to examine the body of evidence, using a systematic approach, to identify putative predictive biomarkers in HER2-positive breast cancer, and discuss the hitherto failure to address the needs of patients. In the future, it is hoped immune-based biomarkers will predict benefit from anti-HER2 treatments in the neoadjuvant and adjuvant settings. In advanced-stage disease, the quantification of tumour heterogeneity using molecular-imaging technology has generated informative data on the success or failure of the antibody-drug conjugate T-DM1. Treatment tailoring remains a high priority, in cost-constrained health-care systems, but such tailoring will require a dramatic shift in the way translational research is being conducted, with the establishment of large, easily accessible, and well-annotated databases of candidate predictive biomarkers. Single-centre biomarker research should become a thing of the past.

New insights on PI3K/AKT pathway alterations and clinical outcomes in breast cancer

PI3K/AKT signaling pathway plays an important role in tumorigenesis and regulates critical cellular functions including survival, proliferation and metabolism. PIK3CA mutations and AKT activation by phosphorylation (pAKT) are often detected in many cancers and especially at high frequencies in breast cancer. Mounting data suggest that PIK3CA mutations or pAKT are mostly associated with better or insignificant outcomes in estrogen receptor-positive (ER+) early stage breast cancer and tend to be with worse prognosis in ER- disease. pAKT expression has been identified to predict paclitaxel chemotherapy benefit in node-positive breast cancer. Preclinical and neoadjuvant trial data suggest that PIK3CA alterations confer resistance to HER2-targeted therapy and are associated with lower pathological complete response (pCR) rate in HER2-positive breast cancer. However, recent results from randomized clinical trials of adjuvant and metastatic settings show that patients with mutant and wildtype PIK3CA tumors derived similar benefit from anti-HER2 therapy. This article, with our new insights, aims to decipher the mixed data and discusses the influence of the potential confounding factors in the assessments. We also share our views for validation of PI3K/AKT alterations in relation to clinical outcome in the context of specific breast cancer subtypes and treatment modalities towards further advance of the precision medicine for breast cancer treatment.