Efficacy of buparlisib in treating breast cancer

Introduction: Breast cancer is the most frequent cancer in women. Despite a decline in breast cancer mortality, prognosis of advanced breast cancer remains poor. In a desperate need to improve breast cancer outcomes, newer agents that target molecular pathways are being tested. Deregulation of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) is frequently found in breast cancer. This can lead to resistance of endocrine therapy and anti-HER2 therapies. Targeting this pathway may restore sensitivity to these compounds. Buparlisib (BKM-120) is an orally active pan-PI3K inhibitor evaluated in different tumor types.

Areas covered: Buparlisib is one of the most investigated PI3K inhibitors. Preclinical and clinical studies of buparlisib in breast cancer are analyzed and discussed. This article reviews the status of buparlisib, completed and ongoing trials, and its safety.

Expert opinion: PI3K inhibitors show promising results in breast cancer. However, we raise a number of issues including the identification of biomarkers to predict treatment response and strategies to counteract resistance. Moreover, its toxicity profile could limit its extensive use.     

用于肿瘤治疗的PI3K/mTOR双重抑制剂的研究进展

磷脂酰肌醇3-激酶（PBK）是细胞内重要的信号转导分子,在细胞存活、增殖和分化过程中起重要调节作用。且是磷脂酰肌醇3-激酶／蛋白激酶B／雷帕霉素靶蛋白信号转导通路的关键节点蛋白,与细胞周期、血管形成、肿瘤发生和侵袭的关系密切,现已证实PBKs是潜力巨大的药物治疗靶点,针对该通路的抑制剂近年来成为研究热点,抗肿瘤治疗前景看好。     

Adjuvant systemic treatment for elderly breast cancer patients; addressing safety concerns

Introduction: The issue of systemic treatment for early breast cancer in the elderly has always been challenging and in spite of the clear evidence of the potential benefits of adjuvant treatment in older women, they are usually undertreated with the potential consequence of worse outcomes.

Areas covered: This article will review the evidence surrounding the various systemic options in the treatment armamentarium of early-stage breast cancer in elderly patients. The risks and benefits, with particular attention to a number of newly introduced targeted agents, along with the potential role of incorporating a combined geriatric/oncologic assessment as a routine part of the management of elderly patients with breast cancer are considered.

Expert opinion: Administration of available options for (neo)adjuvant endocrine, chemo, as well as targeted therapeutics in fit elderly patients is feasible and tolerable; however, a routine input from geriatric medicine and psycho-oncology experts as well as the training of specialized oncology staff with special interest in geriatric oncology are believed to improve the outcome of elderly patients.     

Novel therapeutic strategy for breast cancer: mammalian target of rapamycin inhibition

Background: Mammalian target of rapamycin (mTOR) plays a central role in regulating cellular protein synthesis. Dysregulation of mTOR signaling pathway is strongly associated with tumorigenesis, angiogenesis, tumor progression and drug resistance. Inhibition of mTOR might not only promote cell cycle arrest, but also sensitize resistant cancer cells to chemotherapeutic and other targeted agents. Objective: To review and summarize the mechanism of mTOR on regulation of protein synthesis and latest clinical data, and to discuss the novel therapeutic strategy for the use of mTOR inhibitors in the treatment of breast cancer. Methods: A review of published literatures and conference abstracts obtained from MEDLINE, American Society of Clinical Oncology Meeting and San Antonio Breast Cancer Symposia proceedings for results of previous preclinical and latest clinical studies of mTOR inhibition in breast cancer was performed. Conclusions: mTOR inhibitors seemed to be potentially useful for the treatment of breast cancer with acceptable safety profile. The challenge remains the identification of suitable candidates with different phenotypes. More structured studies incorporating molecular, clinical and translational research need to be initiated. Future research on mTOR inhibitors for breast cancer should focus on the evaluation of optimal schedule, patient selection and combination strategies to maximize the use of this new class of targeted agents.     

Neratinib for the treatment of breast cancer

Introduction: Neratinib is an orally available, pan-HER inhibitor with clinical activity in patients with HER2-amplified and HER2-mutated breast cancer.

Areas covered: A summary of publically available and relevant clinical data on neratinib.

Expert opinion: Neratinib (N) is clearly distinct from lapatinib (L), a difference based on its broad anti-HER effect, its covalent target binding and its toxicity profile. The main toxicity of neratinib is gastro-intestinal and is essentially limited to diarrhea. Although not directly compared with single agent lapatinib, skin toxicity is much less pronounced with N. The direct clinical comparison of N-capecitabine versus L-capecitabine is the subject of the ongoing NALA-trial. In patients with advanced disease, neratinib has clinically relevant activity in patients with trastuzumab(T)-pretreated and unpretreated disease. In patients having completed one year of adjuvant trastuzumab, an additional year of neratinib further reduces the risk of recurrence of invasive disease. The activity of neratinib in HER2-mutated advanced disease is subject of ongoing clinical trials but preclinical and early clinical results are promising. Neratinib is a usefull drug and a valuable addition to the different anti-HER2-drugs avalaible for patients with HER2-overexpressing and HER2-mutated breast cancer.     

PI3K inhibition to overcome endocrine resistance in breast cancer

Introduction: Activation of the phosphatidylinositol-3 kinase (PI3K) pathway is a critical step in oncogenesis and plays a role in the development of treatment resistance for both estrogen receptor (ER) positive and human epidermal growth factor receptor 2 (HER2) positive breast cancers. Hence, there have been efforts to therapeutically inhibit this pathway.

Areas covered: Several inhibitors of PI3K are now progressing through clinical trials with varying degrees of efficacy and toxicity to date. Numerous unresolved questions remain concerning the optimal isoform selectivity of PI3K inhibitors and use of predictive biomarkers. This review examines the most important PI3K inhibitors in ER positive breast cancer to date, with a particular focus on their role in overcoming endocrine therapy resistance and the possible use of PIK3CA mutations as a predictive biomarker.

Expert opinion: We discuss some of the emerging challenges and questions encountered during the development of PI3K inhibitors from preclinical to phase III studies, including other novel biomarkers and future combinations to overcome endocrine resistance.     

Therapeutic options for metastatic breast cancer

Metastatic breast cancer (MBC) remains an incurable disease despite ongoing therapeutic advances. Recently there has been progress extending the range of available cytotoxic chemotherapy drugs and optimizing their scheduling. In addition, a greater understanding of tumor biology has led to the development of a number of targeted therapies. Several of these newer agents, such as trastuzumab, lapatinib and bevacizumab, have demonstrated activity in combination with chemotherapy and have improved the prognosis of patients with MBC. We hope that further progress elucidating the pathophysiology and biology of MBC will continue to lead to corresponding advances in treatment.     

The safety of palbociclib for the treatment of advanced breast cancer

Introduction: Despite improvements in the diagnosis and management of early stage breast cancer, about one third of the patients still progress to metastatic disease. Most of the patients with metastatic breast cancer have a hormone receptor positive and human epidermal growth factor receptor 2 negative subtype with a median survival of more than 3 years. For these patients, endocrine therapy with its favorable toxicity profile is the current standard of care. However, patients with metastatic breast cancer have an incurable disease. Therefore, not only efficacy but also quality of life are key when selecting a therapy regimen.

Areas covered: This paper aims to discuss the efficacy and toxicity profile of the new endocrine-based therapy option palbociclib together with endocrine treatment.

Expert opinion: The addition of targeted agents like palbociclib can overcome intrinsic or acquired resistance to endocrine therapy and substantially prolong progression free survival. The combination of palbociclib plus endocrine therapy is associated with a tolerable and well manageable toxicity profile as well as maintenance of quality of life. Thus, addition of palbociclib to endocrine therapy offers a new and important treatment option for hormone receptor positive metastatic breast cancer.     

Recent advances in the medical management of breast cancer: highlights from the 29th San Antonio Breast Cancer Conference

The 29th edition of the San Antonio Breast Cancer Symposium was attended by a total of > 8000 basic scientists, translational researchers, clinical investigators and physicians gathering from ~ 80 countries worldwide. This is the largest meeting focusing on breast cancer, encompassing a wide array of topics from prevention, aetiology and diagnosis to molecular biology and treatment. From the main presentations at the meeting, it seems clear that combined efforts at prevention and treatment of this disease have translated into small, but significant, achievements. Much of the research in the area is focused on improving the therapeutic ratio of available treatments by better selection of patients.     

Discovery of a Novel Series of Thienopyrimidine as Highly Potent and Selective PI3K Inhibitors

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Lemur tyrosine kinase-3 (LMTK3) as a target in oestrogen positive breast cancer

Oestrogen receptor positive (ER⁺) breast cancers are susceptible to endocrine treatments, such as tamoxifen. However, resistance is a major problem when treating breast cancer with these agents. ERα phosphorylation is implicated in this resistance to tamoxifen, and kinases are the enzymes that catalyse phosphorylation. A kinome search in human breast cancer cells identified lemur tyrosine kinase 3 (LMTK3). In primary breast cancer samples, high nuclear LMTK3 expression was associated with a shorter disease-free survival time. In tamoxifen-resistant cell lines, the addition of LMTK3 siRNA, increased the inhibitory effect of tamoxifen. In nude mice, with established human MCF-7 breast cancer tumours, LMTK3 siRNA decreased tumour growth. In conclusion, LMKT3 is a possible target and marker of breast cancer.     

New agents for the management of resistant metastatic breast cancer

Introduction: Metastatic breast cancer (MBC) is an incurable disease and treatment is directed towards symptom palliation and survival prolongation. Treatment selection in patients is based on tumor biology, age, comorbidities, performance status, tumor burden, and prior treatment history.

Areas covered: This present review summarizes the recent treatment strategies in the management of MBC, highlighting regimens after first-line therapy. Topics discussed include new strategies for endocrine therapy, anti-HER2 therapy, and promising strategies for the management of triple negative breast cancer.

Expert opinion: MBC is a heterogeneous entity and despite recent advances, there is significant room for improvement of treatment beyond first-line therapies. Combination regimens that can maximize clinical efficacy while minimizing toxicities are required. Current investigation approaches in advanced stages of clinical development include immunoconjugates, immune checkpoint blockade, novel cyclin-dependent-kinase inhibitors, and PARP inhibitors for MBC associated with germline BRCA mutations. We recommend that every patient with MBC should be evaluated for clinical trial options.     

Evaluation of WO2013117503 and WO2013117504: the use of PI3K inhibitors to treat cough or idiopathic pulmonary fibrosis

Two applications claim the use of the closely related, broad spectrum phosphatidylinositol 3-kinase inhibitors 2,4-difluoro-N-{2-(methoxy)-5-[4-(4-pyridazinyl)-6-quinolinyl]-3-pyridinyl}benzenesulfonamide (GSK-2126458) and 2,4-difluoro-N-{2-(methoxy)-5-[4-(4-morpholino)-6-quinazolinyl]-3-pyridinyl}benzenesulfonamide for the treatment of idiopathic pulmonary fibrosis and cough, respectively. Some in vitro data are presented in support of these claimed utilities. Since the filing of these applications, GSK-2126458 has commenced a dose-finding Phase I study in patients with idiopathic pulmonary fibrosis.     

Letrozole in the treatment of breast cancer

Endocrine therapy, predominantly using the antioestrogen tamoxifen, has long been a key treatment strategy for oestrogen receptor-positive breast cancer. An alternative approach is to treat patients with aromatase inhibitors, which suppress oestrogen biosynthesis. Letrozole, and other third-generation aromatase inhibitors, are highly specific and potent inhibitors of oestrogen production, which markedly reduce circulating oestrogen levels and whole-body aromatisation of androgen precursors after menopause. In postmenopausal women with hormone receptor-positive or receptor-unknown breast cancer, letrozole has been shown to be superior to megestrol acetate and aminoglutethimide in second-line treatment for advanced breast cancer. Letrozole was also superior to tamoxifen in first-line treatment for advanced breast cancer, as well as in systemic preoperative (neoadjuvant) treatment of locally advanced breast cancer. A recent adjuvant trial demonstrated significant superiority of letrozole over tamoxifen in disease-free survival, and another trial demonstrated that treatment for early breast cancer with letrozole, following 5 years of adjuvant tamoxifen (extended adjuvant therapy), significantly improved disease-free survival compared with placebo, irrespective of nodal status. Ongoing trials will determine whether the optimal use of letrozole in the adjuvant therapy of early breast cancer is as a replacement for tamoxifen, or sequenced additionally before or after tamoxifen.     

PI3K/mTOR双重抑制剂的研究进展

磷脂酰肌醇3-激酶/哺乳动物雷帕霉素靶蛋白(phosphoinosmde-3-kinase/the mammalian target of rapamycin,PI3K/mTOR)双重抑制剂已经成为抗肿瘤药物研发的热点之一。本文介绍芳基脲类和3-吡啶基杂环类等PI3K/mTOR双重抑制剂的化学结构,根据其结构特点及其与PI3Kγ共结晶模式,剖析了两类抑制剂药效团的基本结构。     

Sorafenib for the treatment of breast cancer

Introduction: Breast cancer treatment includes many options depending on the tumor clinicopathological profile, which groups breast cancer into various subtypes. Bevacizumab is currently the only drug capable of targeting angiogenesis in breast cancer. Sorafenib has also been studied in combination with other agents.

Areas covered: Pharmacological aspects of sorafenib, including results from preclinical studies on breast cancer cells; findings about clinical efficacy and safety in both single-arm and randomized clinical trials; ongoing trials.

Expert opinion: Since sorafenib as a single agent has shown limited efficacy in breast cancer, its combination with other drugs is under investigation. Dose reduction is the main challenge when sorafenib is combined with chemotherapy or endocrine therapy. Although randomized phase-II trials on sorafenib plus chemotherapy versus chemotherapy alone have shown potential benefits in progression-free survival, preliminary results from a phase-III study in combination with capecitabine are negative. The definitive results of this trial and results from other ongoing phase-II trials will determine further developments of sorafenib in breast cancer. Although these additional data could help determine the most appropriate dose, drug combination and patient settings, a confirmation of the preliminary negative results reported in the phase-III trial are likely to discourage further use of sorafenib in breast cancer, given its non-negligible toxicity, lack of predicting markers, and the number of more promising drugs for breast cancer.     

Dual inhibitor of phosphoinositide 3-kinase/mammalian target of rapamycin NVP-BEZ235 effectively inhibits cisplatin-resistant urothelial cancer cell growth through autophagic flux

Purpose

Therapeutically induced autophagic cell death has been proven to be effective in cases of solid tumors. The dual phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) inhibitor NVP-BEZ235 possesses antitumor activity against solid tumors. Inhibition of mTOR has been shown to elicit autophagy. In this study, we examined the antiproliferation and autophagic activities of NVP-BEZ235 in parental and cisplatin-resistant urothelial carcinoma (UC) cells.

Materials and methods

Two UC cell lines, NTUB1 and a cisplatin-resistant subline N/P(14), were applied to examine the cytotoxic effect of NVP-BEZ-235. The cell death mechanism was also evaluated.

Results

NVP-BEZ235 was effective in inhibiting the growth of UC cells including parental and cisplatin-resistant cells on flow cytometry assay and Western blot. Although NVP-BEZ235 did not induce LC3-II conversion, it did elicit acidic vesicular organelle (AVO) development on flow cytometry. On Western blot, NVP-BEZ235 decreased p62 and phospho-Rb expressions in a concentration-dependent manner. GFP-LC3 conversion and the appearance of cleaved-GFP following NVP-BEZ235 treatment were demonstrated on Western blot. In addition, lysosomotropic inhibition of autophagy by chloroquine (CQ), an agent that is currently in clinical use and a known antagonist of autophagy, resulted in proliferation of UC cells. Thus, inhibition of autophagic flux by CQ appears to be a survival mechanism that counteracts the anticancer effects of NVP-BEZ235.

Conclusions

We demonstrated that NVP-BEZ235 inhibits UC cell proliferation by activating autophagic flux and cell cycle arrest, but does not induce apoptotic cell death. Our findings suggest that the anticancer efficacy of NVP-BEZ235 is due to autophagic flux and co-treatment with CQ counteracts the cytotoxic effect.     

Ertumaxomab: a trifunctional antibody for breast cancer treatment

Ertumaxomab is an intact bispecific antibody targeting HER2/neu and CD3 with preferential binding to activating Fcγ type I/III-receptors, resulting in the formation of a tri-cell complex among tumour cell, T cell and accessory cell. Recently, the antibody demonstrated antitumour efficacy against HER2/neu low-expressing tumours resistant to trastuzumab. Data from a completed Phase I study in metastatic breast cancer patients indicates strong immune responses. Owing to efficient tumour cell destruction by humoral and T-cell-dependent mechanisms, differing from conventional HER2/neu directed treatments, and a potential for long-lasting antitumour immunoreactivity, ertumaxomab is at present investigated within Phase II studies enrolling metastatic breast cancer patients even without HER2/neu gene amplification.     

甘草次酸对胃癌细胞SGC7901增殖、凋亡及PI3K-Akt-mTOR通路的影响

目的 探究甘草次酸对胃癌SGC7901细胞增殖、凋亡及PI3K-Akt-mTOR通路的影响。方法 体外培养胃癌SGC7901细胞,分为对照组和甘草次酸低、中、高浓度（12.5、25.0、50.0 μmol/L）组,药物处理24、48、72 h后,CCK-8法检测细胞增殖情况;药物处理48 h后,流式细胞仪检测细胞周期分布及细胞凋亡情况;Western blotting检测凋亡相关蛋白Bcl-2、Bax、cleaved Caspase-3以及PI3K-Akt-mTOR信号通路中磷酸化PI3K、Akt、mTOR蛋白表达水平。结果 甘草次酸低、中、高浓度组胃癌SGC7901细胞增殖受到明显抑制,并呈时间和剂量相关性（P<0.05）。与对照组比较,甘草次酸低、中、高浓度组胃癌SGC7901细胞G₀/G₁期细胞比例显著降低（P<0.05）,G₂/M期细胞比例及凋亡率显著升高（P<0.05）,Bax、cleaved Caspase-3蛋白表达水平显著升高（P<0.05）,Bcl-2、p-PI3K、p-Akt、p-mTOR蛋白表达水平显著降低（P<0.05）。结论 甘草次酸可抑制胃癌SGC7901细胞增殖,促进其凋亡,其机制可能与抑制PI3K-Akt-mTOR信号通路激活有关。