Clinical Significance And Basic Research Of PIK3CA Mutations In HER2 Positive Breast Cancer

Objective:Breast cancer(BC)has surpassed lung cancer to become the most common cancer in clinical diagnosis.Furthermore,it is the main cause of cancer death in women.Among them,the protein receptor Human Epidermal Growth Factor Receptor 2(HER2)amplification or the HER2/neu overexpression accounted for about 25–30%.Before the advent of trastuzumab,HER2 positive was an important sign of poor prognosis in breast cancer.A major feature of this molecular classification is its high degree of malignancy and easy metastasis.Trastuzumab,a humanized Ig G1 monoclonal antibody derived from recombinant DNA targeting the HER2 receptor,was approved by the US Food and Drug Administration(FDA)in 1998.Concurrent treatment with chemotherapy can significantly prolong the progressionfree survival of patients and improve the overall survival rate.This established the position of the drug in the treatment of HER2 positive BC.However,in a wide range of clinical applications,it is still observed that about 60% of patients have varying degrees of insensitivity to treatment.Studies have found that the mutation of phosphoinositide 3-kinase(PI3K)downstream of the HER2 pathway reactivates the pathway,which could be one of the causes for drug resistance.However,whether PIK3CA(Phosphatidylinositol-4,5-bisphosphate 3-kinase,catalytic subunit alpha)mutation is associated with survival treated with trastuzumab in HER2-positive breast cancer remains unclear.In this study,patients with initial treated HER2 positive BC and previously detected PIK3 CA gene mutations were collected from Xijing Hospital from January 1,2016 to December 31,2019,and the efficacy of PIK3 CA mutation and neoadjuvant chemotherapy(NCT)combined with trastuzumab was analyzed.Although many previous studies have explored the use of different PI3 K inhibitors in HER2 positive BC,almost all studies have stagnated due to side effects or insufficient clinical efficacy.With the approval of the PI3 K inhibitor alpelisib by the US FDA,whether it can be used in HER2-positive BC has also become a hot topic.Therefore,we combine PI3 K inhibitors with anti-HER2 drugs to enhance the ability to suppress tumors.Methods1.Patients with initial treatment HER2 positive BC and previous testing for PIK3 CA gene mutation from January 1,2016 to December 31,2019 were included.Patient information was collected including age,marital status,pregnancy,miscarriage,fertility,menopausal status,clinical T stage of the tumor,N stage,who histological grade,ER status,PR status,Ki67,surgical status,usage of anthracyclines and enfants,PIK3 CA mutation status,whether a pathological complete response(p CR)was achieved,and survival.Factors influencing the achievement of PCR after surgery were evaluated by logistic regression analysis.2.PI3 K p110a protein expression in relation to survival and plotted survival curves in HER2 positive BC patients using Kaplan Meier plotter extraction.Meanwhile Kaplan Meier was employed to draw the survival curve and log rank test was used for survival analysis using the data in this study.The influencing factors of survival were evaluated by COX regression after.All tests were two-sided,and P < 0.05 was considered statistically significant.3.Tissue wax blocks from wild-type and mutant-type patients were immunohistochemically stained and scored using phosphor-Akt(ser473)antibody and Mann Whitney U test was employed to analyze the difference of immunohistochemical results between two groups.4.In this study,emulsifying solvent volatilization method was used to prepare PLGA nanoparticles combined with trastuzumab and aspirin,named Ap-Tra-NPs.Ap-Tra-NPs were prepared by Malvern particle size analyzer and TEM analysis.Finally,the entrapment efficiency and drug loading efficiency of the linked drugs were analyzed by HPLC with a BCA protein quantitative detection kit.5.CCK8 assay was employed to analyze the killing ability of Ap-Tra-NPs on SK-BR-3breast cancer cells.(All tests were two-sided,and a statistically significant result was defined as P 0.05.)Results1.156 patients were included in this study.Chi square test results suggested that patients with higher T stage,higher N stage,and PIK3 CA mutations were less likely to achieve p CR With the achievement of p CR after NCT as the event endpoint,the results of univariate logistic regression showed that patients with higher T stage and higher N score were less likely to achieve p CR after NCT.Multivariate logistic backward stepwise regression was used and the final model contained T and N stage and PIK3 CA mutation.Where PIK3 CA mutation p-value was 0.036,or 0.37,95% CI 0.15-0.94.2.Plotting survival curves using data from the present study similarly showed worse survival in patients with PIK3 CA mutations compared to those without mutations.The target protein,PI3 K p110a,was selected to plot the survival curve with all-cause death as the final event.The data presented in this study suggest that patients with high PI3 K p110a expression have worse survival than those with low expression(P = 0.032).The population distribution was suggestive that patients with PIK3 CA mutations and not achieving a p CR after NCT had worse survival with higher T stage and higher N stage.Multivariate Cox forward stepwise regression was used to analyze final T and N stage only into the model,and neither PIK3 CA mutation nor PCR were included.3.The Mann-Whitney U test yielded P = 0.0002,suggesting aberrant activation of the p3k/ Akt / m TOR pathway within tumors from patients with PIK3 CA mutations,which was significantly higher than that of wild-type patients.4.In this paper,Ap-Tra-NPs loaded with alpelisib and trastuzumab were successfully prepared by emulsification solvent volatilization method.ζ Potential:-26.4 MV;Particle size about 232.7 nm;TEM suggested a homogeneous spherical shape inside the Ap-TraNPs The alpelisib modification ratio was 70.74,and the drug loading capacity was 13.74;The trastuzumab modification ratio was 96.05,and the drug loading capacity was 8.16.5.The CCK8 cytotoxicity assay showed that the Ap-Tra-NPs group,Tra-Ap group,and both AP and Tra groups were significantly toxic to SKBR3 cells,with the Ap-Tra-NPs group being the most toxic.Conclusions1.PIK3 CA mutation,as a poor genetic mutation,also plays an important role in HER2 positive BC.Based on our study,we observed that status of PIK3 CA mutation was one of the independent influencing factors for achieving p CR after NCT with trastuzumab in breast cancer.PIK3 CA mutations were not significantly associated with T and N stage,molecular typing,or any other factors such as family history of cancer or marital or reproductive history.2.After NCT and one-year anti-HER2 therapy,PIK3 CA mutated HER2 positive BC had a worse prognosis,but multivariate COX regression did not suggest PIK3 CA mutation as an independent risk factor for poor prognosis.3.The PI3K/AKT/m TOR pathway is abnormally activated in breast cancer patients with PIK3 CA mutations.4.We have successfully prepared relatively stable nanoparticles Ap-Tra-NPs It contains a certain amount of alpelisib and trastuzumab,which is expected to play a role in the treatment of HER2 positive BC5.Ap-Tra-NPs based on nanotechnology combined with free drugs can inhibit the growth of tumor cells more significantly and have a stronger killing effect on tumor.