Everolimus plus exemestane for the treatment of advanced breast cancer: a review of subanalyses from BOLERO-2

Current and Novel Treatment Options in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer

Metastatic breast cancer (mBC) remains an incurable disease, and most patients will experience disease progression during their treatment course. Although endocrine therapy remains the mainstay of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative mBC, significant progress has been and continues to be made in the treatment of this BC subtype. The discovery of molecular markers, mutations in key cellular pathways, and genomic signatures have led to the development of novel and targeted agents, such as antibody-drug conjugates, oral selective estrogen receptor downregulators, and inhibitors of the PI3K/AKT/mTOR pathway. This has resulted in significant improvements in the survival and quality of life of patients. With the increasing number of treatment options for patients, appropriate drug sequencing remains a challenge. Treatment discussions should involve patient-physician shared decision making, with consideration of genomic data, previous lines of therapy, side effect profiles, and clinical trial enrollment.

Lobular Carcinoma of the Breast: A Comprehensive Review with Translational Insights

The second most common breast carcinoma, invasive lobular carcinoma, accounts for approximately 15% of tumors of breast origin. Its incidence has increased in recent times due in part to hormone replacement therapy and improvement in diagnostic modalities. Although believed to arise from the same cell type as their ductal counterpart, invasive lobular carcinomas (ILCs) are a distinct entity with different regulating genetic pathways, characteristic histologies, and different biology. The features most unique to lobular carcinomas include loss of E-Cadherin leading to discohesion and formation of a characteristic single file pattern on histology. Because most of these tumors exhibit estrogen receptor positivity and Her2 neu negativity, endocrine therapy has predominated to treat these tumors. However novel treatments like CDK4/6 inhibitors have shown importance and antibody drug conjugates may be instrumental considering newer categories of Her 2 Low breast tumors. In this narrative review, we explore multiple pathological aspects and translational features of this unique entity. In addition, due to advancement in technologies like spatial transcriptomics and other hi-plex technologies, we have tried to enlist upon the characteristics of the tumor microenvironment and the latest associated findings to better understand the new prospective therapeutic options in the current era of personalized treatment.

The Long Scientific Journey of Sirolimus (Rapamycin): From the Soil of Easter Island (Rapa Nui) to Applied Research and Clinical Trials on β-Thalassemia and Other Hemoglobinopathies

In this review article, we present the fascinating story of rapamycin (sirolimus), a drug able to induce γ-globin gene expression and increased production of fetal hemoglobin (HbF) in erythroid cells, including primary erythroid precursor cells (ErPCs) isolated from β-thalassemia patients. For this reason, rapamycin is considered of great interest for the treatment of β-thalassemia. In fact, high levels of HbF are known to be highly beneficial for β-thalassemia patients. The story of rapamycin discovery began in 1964, with METEI, the Medical Expedition to Easter Island (Rapa Nui). During this expedition, samples of the soil from different parts of the island were collected and, from this material, an antibiotic-producing microorganism (Streptomyces hygroscopicus) was identified. Rapamycin was extracted from the mycelium with organic solvents, isolated, and demonstrated to be very active as an anti-bacterial and anti-fungal agent. Later, rapamycin was demonstrated to inhibit the in vitro cell growth of tumor cell lines. More importantly, rapamycin was found to be an immunosuppressive agent applicable to prevent kidney rejection after transplantation. More recently, rapamycin was found to be a potent inducer of HbF both in vitro using ErPCs isolated from β-thalassemia patients, in vivo using experimental mice, and in patients treated with this compound. These studies were the basis for proposing clinical trials on β-thalassemia patients.

HER3/Akt/mTOR pathway is a key therapeutic target for the reduction of triple‑negative breast cancer metastasis via the inhibition of CXCR4 expression

Triple‑negative breast cancer (TNBC), a highly metastatic subtype of breast cancer, and it has the worst prognosis among all subtypes of breast cancer. However, no effective systematic therapy is currently available for TNBC metastasis. Therefore, novel therapies targeting the key molecular mechanisms involved in TNBC metastasis are required. The present study examined whether the expression levels of human epidermal growth factor receptor 3 (HER3) were associated with the metastatic phenotype of TNBC, and evaluated the potential of HER3 as a therapeutic target in vitro and in vivo. A new highly metastatic 4T1 TNBC cell line, termed 4T1‑L8, was established. The protein expression levels in 4T1‑L8 cells were measured using luminex magnetic bead assays and western blot analysis. The HER3 expression levels and distant metastasis‑free survival (DMFS) in TNBC were analyzed using Kaplan‑Meier Plotter. Transwell migration and invasion assays were performed to detect migration and invasion. The anti‑metastatic effects were determined in an experimental mouse model of metastasis. The results revealed that the increased expression of the HER3/Akt/mTOR pathway was associated with a greater level of cell migration, invasion and metastasis of TNBC cells. In addition, it was found that high expression levels of HER3 were associated with a poor DMFS. The inhibition of the HER3/Akt/mammalian target of rapamycin (mTOR) pathway decreased the migration, invasion and metastasis of TNBC cells by decreasing the expression of C‑X‑C chemokine receptor type 4 (CXCR4). Furthermore, treatment of metastatic TNBC cells with everolimus inhibited their migration, invasion and metastasis by decreasing CXCR4 expression. Thus, targeting the HER3/Akt/mTOR pathway opens up a new avenue for the development of therapeutics against TNBC metastasis; in addition, everolimus may prove to be an effective therapeutic agent for the suppression of TNBC metastasis.

A Comprehensive Review of Interventional Clinical Trials in Patients with Bone Metastases

Bone metastasis is one of the most important factors associated with poor prognosis for patients with prostate, breast, thyroid, and lung cancer. In the past two decades, 651 clinical trials, including 554 interventional trials, were being registered in ClinicalTrials.gov and pharma.id.informa.com to combat bone metastases from different perspectives. In this review, we comprehensively analyzed, regrouped, and discussed all the interventional trials on bone metastases. Clinical trials were re-grouped into bone-targeting agents, radiotherapy, small molecule targeted therapy, combination therapy, and others, based on the different mechanisms of action including modifying the bone microenvironment and preventing the growth of cancer cells. We also discussed the potential strategies that might improve overall survival and progression-free survival of patients with bone metastases in the future.

XENERA-1: a randomised double-blind Phase II trial of xentuzumab in combination with everolimus and exemestane versus everolimus and exemestane in patients with hormone receptor-positive/HER2-negative metastatic breast cancer and non-visceral disease

BACKGROUND

Xentuzumab is a humanised monoclonal antibody that binds to IGF-1 and IGF-2, neutralising their proliferative activity and restoring inhibition of AKT by everolimus. This study evaluated the addition of xentuzumab to everolimus and exemestane in patients with advanced breast cancer with non-visceral disease.

METHODS

This double-blind, randomised, Phase II study was undertaken in female patients with hormone-receptor (HR)-positive/human epidermal growth factor 2 (HER2)-negative advanced breast cancer with non-visceral disease who had received prior endocrine therapy with or without CDK4/6 inhibitors. Patients received a weekly intravenous infusion of xentuzumab (1000 mg) or placebo in combination with everolimus (10 mg/day orally) and exemestane (25 mg/day orally). The primary endpoint was progression-free survival (PFS) per independent review.

RESULTS

A total of 103 patients were randomised and 101 were treated (n = 50 in the xentuzumab arm and n = 51 in the placebo arm). The trial was unblinded early due to high rates of discordance between independent and investigator assessment of PFS. Per independent assessment, median PFS was 12.7 (95% CI 6.8-29.3) months with xentuzumab and 11.0 (7.7-19.5) months with placebo (hazard ratio 1.19; 95% CI 0.55-2.59; p = 0.6534). Per investigator assessment, median PFS was 7.4 (6.8-9.7) months with xentuzumab and 9.2 (5.6-14.4) months with placebo (hazard ratio 1.23; 95% CI 0.69-2.20; p = 0.4800). Tolerability was similar between the arms, with diarrhoea (33.3-56.0%), fatigue (33.3-44.0%) and headache (21.6-40.0%) being the most common treatment-emergent adverse events. The incidence of grade ≥ 3 hyperglycaemia was similar between the xentuzumab (2.0%) and placebo (5.9%) arms.

CONCLUSIONS

While this study demonstrated that xentuzumab could be safely combined with everolimus and exemestane in patients with HR-positive/HER2-negative advanced breast cancer with non-visceral disease, there was no PFS benefit with the addition of xentuzumab. Trial registration ClinicalTrials.gov, NCT03659136. Prospectively registered, September 6, 2018.

Effects of Sirolimus treatment on patients with β-Thalassemia: Lymphocyte immunophenotype and biological activity of memory CD4+ and CD8+ T cells

Inhibitors of the mammalian target of rapamycin (mTOR) have been proposed to improve vaccine responses, especially in the elderly. Accordingly, testing mTOR inhibitors (such as Sirolimus) and other geroprotective drugs might be considered a key strategy to improve overall health resilience of aged populations. In this respect, Sirolimus (also known as rapamycin) is of great interest, in consideration of the fact that it is extensively used in routine therapy and in clinical studies for the treatment of several diseases. Recently, Sirolimus has been considered in laboratory and clinical studies aimed to find novel protocols for the therapy of hemoglobinopathies (e.g. β-Thalassemia). The objective of the present study was to analyse the activity of CD4⁺ and CD8⁺ T cells in β-Thalassemia patients treated with Sirolimus, taking advantages from the availability of cellular samples of the NCT03877809 clinical trial. The approach was to verify IFN-γ releases following stimulation of peripheral blood mononuclear cells (PBMCs) to stimulatory CEF and CEFTA peptide pools, stimulatory for CD4⁺ and CD8⁺ T cells, respectively. The main results of the present study are that treatment of β-Thalassemia patients with Sirolimus has a positive impact on the biological activity and number of memory CD4⁺ and CD8⁺ T cells releasing IFN-γ following stimulation with antigenic stimuli present in immunological memory. These data are to our knowledge novel and in our opinion of interest, in consideration of the fact that β-Thalassemia patients are considered prone to immune deficiency.

Expression of γ-globin genes in β-thalassemia patients treated with sirolimus: results from a pilot clinical trial (Sirthalaclin)

Introduction

β-thalassemia is caused by autosomal mutations in the β-globin gene, which induce the absence or low-level synthesis of β-globin in erythroid cells. It is widely accepted that a high production of fetal hemoglobin (HbF) is beneficial for patients with β-thalassemia. Sirolimus, also known as rapamycin, is a lipophilic macrolide isolated from a strain of Streptomyces hygroscopicus that serves as a strong HbF inducer in vitro and in vivo. In this study, we report biochemical, molecular, and clinical results of a sirolimus-based NCT03877809 clinical trial (a personalized medicine approach for β-thalassemia transfusion-dependent patients: testing sirolimus in a first pilot clinical trial, Sirthalaclin).

Methods

Accumulation of γ-globin mRNA was analyzed using reverse-transcription quantitative polymerase chain reaction (PCR), while the hemoglobin pattern was analyzed using high-performance liquid chromatography (HPLC). The immunophenotype was analyzed using a fluorescence-activated cell sorter (FACS), with antibodies against CD3, CD4, CD8, CD14, CD19, CD25 (for analysis of peripheral blood mononuclear cells), or CD71 and CD235a (for analysis of in vitro cultured erythroid precursors).

Results

The results were obtained in eight patients with the β+/β+ and β+/β0 genotypes, who were treated with a starting dosage of 1 mg/day sirolimus for 24-48 weeks. The first finding of this study was that the expression of γ-globin mRNA increased in the blood and erythroid precursor cells isolated from β-thalassemia patients treated with low-dose sirolimus. This trial also led to the important finding that sirolimus influences erythropoiesis and reduces biochemical markers associated with ineffective erythropoiesis (excess free α-globin chains, bilirubin, soluble transferrin receptor, and ferritin). A decrease in the transfusion demand index was observed in most (7/8) of the patients. The drug was well tolerated, with minor effects on the immunophenotype, and an only side effect of frequently occurring stomatitis.

Conclusion

The data obtained indicate that low doses of sirolimus modify hematopoiesis and induce increased expression of γ-globin genes in a subset of patients with β-thalassemia. Further clinical trials are warranted, possibly including testing of the drug in patients with less severe forms of the disease and exploring combination therapies.

Optimal Strategy and Benefit of Pulsed Therapy Depend On Tumor Heterogeneity and Aggressiveness at Time of Treatment Initiation

Therapeutic resistance is a fundamental obstacle in cancer treatment. Tumors that initially respond to treatment may have a preexisting resistant subclone or acquire resistance during treatment, making relapse theoretically inevitable. Here, we investigate treatment strategies that may delay relapse using mathematical modeling. We find that for a single-drug therapy, pulse treatment-short, elevated doses followed by a complete break from treatment-delays relapse compared with continuous treatment with the same total dose over a length of time. For tumors treated with more than one drug, continuous combination treatment is only sometimes better than sequential treatment, while pulsed combination treatment or simply alternating between the two therapies at defined intervals delays relapse the longest. These results are independent of the fitness cost or benefit of resistance, and are robust to noise. Machine-learning analysis of simulations shows that the initial tumor response and heterogeneity at the start of treatment suffice to determine the benefit of pulsed or alternating treatment strategies over continuous treatment. Analysis of eight tumor burden trajectories of breast cancer patients treated at Memorial Sloan Kettering Cancer Center shows the model can predict time to resistance using initial responses to treatment and estimated preexisting resistant populations. The model calculated that pulse treatment would delay relapse in all eight cases. Overall, our results support that pulsed treatments optimized by mathematical models could delay therapeutic resistance.

Application of mTORC1 Inhibitors for Tissue-Agnostic Management of Standard-Therapy-Refractory Solid Tumors

In this analysis, we examined the efficacy, feasibility, and limitations of the application of mTOR inhibitors based on the individual molecular profiles of pretreated cancer patients after the failure of all standard treatments in the palliative setting. In this single-center, real-world analysis of our platform for precision medicine, we analyzed the molecular characteristics of 71 cancer patients. The tumor samples of the patients were analyzed using next-generation sequencing panels of mutation hotspots, microsatellite stability testing, and immunohistochemistry. All profiles were reviewed by a multidisciplinary team to provide a targeted treatment recommendation after a consensus discussion. Seventy-one cancer patients with activation of the mTOR pathway were offered an mTORC1-inhibitor-based targeted therapy, and twenty-three (32.4%) of them eventually received the targeted therapy. Only three patients (4.2%) achieved stable disease, of whom one experienced progressive disease again after 9.1 months. The median time to treatment failure was 2.8 months. In total, 110 mutations were detected in 60 patients (84.5%). The three most frequent mutations were found in TP53, PTEN, and KRAS, which accounted for over 50% (56.4%) of all mutations. In sum, in selected patients with heavily pretreated solid tumors with activation of the mTOR pathway, the antitumoral activity of mTORC1 inhibition was weak.

Possible effects of sirolimus treatment on the long‑term efficacy of COVID‑19 vaccination in patients with β‑thalassemia: A theoretical perspective

The pandemic caused by the severe acute respiratory syndrome coronavirus (SARS‑CoV‑2), responsible for coronavirus disease 2019 (COVID‑19) has posed a major challenge for global health. In order to successfully combat SARS‑CoV‑2, the development of effective COVID‑19 vaccines is crucial. In this context, recent studies have highlighted a high COVID‑19 mortality rate in patients affected by β‑thalassemia, probably due to their co‑existent immune deficiencies. In addition to a role in the severity of SARS‑CoV‑2 infection and in the mortality rate of COVID‑19‑infected patients with thalassemia, immunosuppression is expected to deeply affect the effectivity of anti‑COVID‑19 vaccines. In the context of the interplay between thalassemia‑associated immunosuppression and the effectiveness of COVID‑19 vaccines, the employment of immunomodulatory molecules is hypothesized. For instance, short‑term treatment with mammalian target of rapamycin inhibitors (such as everolimus and sirolimus) has been found to improve responses to influenza vaccination in adults, with benefits possibly persisting for a year following treatment. Recently, sirolimus has been considered for the therapy of hemoglobinopathies (including β‑thalassemia). Sirolimus induces the expression of fetal hemoglobin (and this may contribute to the amelioration of the clinical parameters of patients with β‑thalassemia) and induces autophagy (thereby reducing the excessive levels of α‑globin). It may also finally contribute to the mobilization of erythroid cells from the bone marrow (thereby reducing anemia). In the present study, the authors present the hypothesis that sirolimus treatment, in addition to its beneficial effects on erythroid‑related parameters, may play a crucial role in sustaining the effects of COVID‑19 vaccination in patients with β‑thalassemia. This hypothesis is based on several publications demonstrating the effects of sirolimus treatment on the immune system.

Combination of AZD3463 and DZNep Prevents Bone Metastasis of Breast Cancer by Suppressing Akt Signaling

Osteolysis resulting from osteoclast overactivation is one of the severe complications of breast cancer metastasis to the bone. Previous studies reported that the anti-cancer agent DZNep induces cancer cell apoptosis by activating Akt signaling. However, the effect of DZNep on breast cancer bone metastasis is unknown. We previously found that DZNep enhances osteoclast differentiation by activating Akt. Therefore, we explored the use of the anti-cancer agent AZD3463 (an Akt inhibitor) along with DZNep, as AZD3463 can act as an anti-cancer agent and can also potentially ameliorate bone erosion. We evaluated osteoclast and breast cancer cell phenotypes and Akt signaling in vitro by treating cells with DZNep and AZD3463. Furthermore, we developed a breast cancer bone metastasis animal model in mouse tibiae to further determine their combined effects in vivo. Treatment of osteoclast precursor cells with DZNep alone increased osteoclast differentiation, bone resorption, and expression of osteoclast-specific genes. These effects were ameliorated by AZD3463. The combination of DZNep and AZD3463 inhibited breast cancer cell proliferation, colony formation, migration, and invasion. Finally, intraperitoneal injection of DZNep and AZD3463 ameliorated tumor progression and protected against bone loss. In summary, DZNep combined with AZD3463 prevented skeletal complications and inhibited breast cancer progression by suppressing Akt signaling.

Safety and efficacy of everolimus (EVE) plus exemestane (EXE) in postmenopausal women with locally advanced or metastatic breast cancer: final results from EVEREXES

BACKGROUND

This study was conducted to collect clinical safety, tolerability, and efficacy data with the use of everolimus (EVE) combined with exemestane (EXE) in patients with advanced breast cancer (ABC).

METHODS

The EVEREXES trial initiated in 2012, provided early access to the first dual blockade treatment with EVE + EXE in patients with HR+, HER2 - ABC in Asia and other emerging growth countries. Postmenopausal women with HR+, HER2 - ABC who had documented recurrence or progression, following a nonsteroidal aromatase inhibitor therapy, were treated with EVE (10 mg/day) + EXE (25 mg/day) orally.

RESULTS

A total of 235 patients received ≥ 1 dose of study medication. At the end of the study, all patients ceased the treatment. Disease progression (66.0%) was the primary reason of discontinuation. The most common AEs (≥ 20%) were stomatitis, decreased appetite, hyperglycemia, rash, aspartate aminotransferase increased, anemia, alanine aminotransferase increased, cough, and fatigue. No new safety concerns were identified in the current study. Median progression-free survival (PFS) in the Asian subset was similar to that of the overall population (9.3 months in both groups). Confirmed overall response rate (ORR) was achieved for 19.6% of the patients. Efficacy of EVE + EXE across subgroups (prior CT, line of treatment, and presence of visceral metastases) was maintained.

CONCLUSION

The safety and efficacy results from EVEREXES trial are consistent to data previously reported in BOLERO-2. These results support that EVE + EXE could be a viable treatment option for the postmenopausal women with HR+, HER2 - ABC in Asian region.

Bone metastasis: mechanisms, therapies, and biomarkers

Skeletal metastases are frequent complications of many cancers, causing bone complications (fractures, bone pain, disability) that negatively affect the patient's quality of life. Here, we first discuss the burden of skeletal complications in cancer bone metastasis. We then describe the pathophysiology of bone metastasis. Bone metastasis is a multistage process: long before the development of clinically detectable metastases, circulating tumor cells settle and enter a dormant state in normal vascular and endosteal niches present in the bone marrow, which provide immediate attachment and shelter, and only become active years later as they proliferate and alter the functions of bone-resorbing (osteoclasts) and bone-forming (osteoblasts) cells, promoting skeletal destruction. The molecular mechanisms involved in mediating each of these steps are described, and we also explain how tumor cells interact with a myriad of interconnected cell populations in the bone marrow, including a rich vascular network, immune cells, adipocytes, and nerves. We discuss metabolic programs that tumor cells could engage with to specifically grow in bone. We also describe the progress and future directions of existing bone-targeted agents and report emerging therapies that have arisen from recent advances in our understanding of the pathophysiology of bone metastases. Finally, we discuss the value of bone turnover biomarkers in detection and monitoring of progression and therapeutic effects in patients with bone metastasis.

Bone metastases

Bone is the most frequent site for metastasis for many cancers, notably for tumours originating in the breast and the prostate. Tumour cells can escape from the primary tumour site and colonize the bone microenvironment. Within the bone, these disseminated tumour cells, as well as those arising in the context of multiple myeloma, may assume a state of dormancy, remaining quiescent for years before resuming proliferation and causing overt metastasis, which causes bone destruction via activation of osteoclast-mediated osteolysis. This structural damage can lead to considerable morbidity, including pain, fractures and impaired quality of life. Although treatment of bone metastases and myeloma bone disease is rarely curative, disease control is often possible for many years through the use of systemic anticancer treatments on a background of multidisciplinary supportive care. This care should include bone-targeted agents to inhibit tumour-associated osteolysis and prevent skeletal morbidity as well as use of appropriate local treatments such as radiation therapy, orthopaedic surgery and specialist palliative care to minimize the impact of metastatic bone disease on physical functioning. In this Primer, we provide an overview of the clinical features, the pathophysiology and the specific treatment approaches to prevent and treat bone metastases from solid tumours as well as myeloma bone disease.

Desloratadine and loratadine stand out among common H1-antihistamines for association with improved breast cancer survival

BACKGROUND

As tumors maintain an inflammatory microenvironment, anti-inflammatory medication can be useful in cancer therapy. We have previously shown an association with improved survival in melanoma for use of the H₁-antihistamines desloratadine and loratadine, and here we examine use of H₁-antihistamines and breast cancer mortality.

MATERIAL AND METHODS

We investigated use of the six major H₁-antihistamines (cetirizine, clemastine, desloratadine, ebastine, fexofenadine and loratadine) and breast cancer-specific and overall mortality in a nation-wide register-based study of all 61,627 Swedish women diagnosed with breast cancer 2006-2013. Both peri- and post-diagnostic antihistamine use was analyzed using Cox regression models. Analyses were stratified for age and subgroup analyses based on estrogen receptor status and menopausal status were performed.

RESULTS

We found a consistently improved survival of desloratadine users (HR = 0.67; 95% CI 0.55-0.81, p < .001), as well as of loratadine users (HR = 0.80; 95% CI 0.67-0.95, p = .012), relative to nonusers, regardless of patient age, menopause, estrogen receptor status or stage of the tumor, or whether breast cancer-specific or overall survival was analyzed. The survival of users of other antihistamines varied relative to non-users.

CONCLUSION

Based on their safety and current use within the patient population, together with our observations, we suggest the initiation of trials of desloratadine and loratadine as treatment of breast cancer as well as studies of the mechanism behind their possible effect. Further studies on any effects of other H₁-antihistamines may also be merited, as well as of H₁-antihistamine use and survival in other malignancies.

Capivasertib, an AKT Kinase Inhibitor, as Monotherapy or in Combination with Fulvestrant in Patients with AKT1 E17K-Mutant, ER-Positive Metastatic Breast Cancer

PURPOSE

The activating mutation AKT1 E17K occurs in approximately 7% of estrogen receptor-positive (ER+) metastatic breast cancer (MBC). We report, from a multipart, first-in-human, phase I study (NCT01226316), tolerability and activity of capivasertib, an oral AKT inhibitor, as monotherapy or combined with fulvestrant in expansion cohorts of patients with AKT1 E17K-mutant ER+ MBC.

PATIENTS AND METHODS

Patients with an AKT1 E17K mutation, detected by local (next-generation sequencing) or central (plasma-based BEAMing) testing, received capivasertib 480 mg twice daily, 4 days on, 3 days off, weekly or 400 mg twice daily combined with fulvestrant at the labeled dose. Study endpoints included safety, objective response rate (ORR; RECIST v1.1), progression-free survival (PFS), and clinical benefit rate at 24 weeks (CBR24). Biomarker analyses were conducted in the combination cohort.

RESULTS

From October 2013 to August 2018, 63 heavily pretreated patients received capivasertib (20 monotherapy, 43 combination). ORR was 20% with monotherapy, and within the combination cohort was 36% in fulvestrant-pretreated and 20% in fulvestrant-naïve patients, although the latter group may have had more aggressive disease at baseline. AKT1 E17K mutations were detectable in plasma by BEAMing (95%, 41/43), droplet digital PCR (80%, 33/41), and next-generation sequencing (76%, 31/41). A ≥50% decrease in AKT1 E17K at cycle 2 day 1 was associated with improved PFS. Combination therapy appeared more tolerable than monotherapy [most frequent grade ≥3 adverse events: rash (9% vs. 20%), hyperglycemia (5% vs. 30%), diarrhea (5% vs. 10%)].

CONCLUSIONS

Capivasertib demonstrated clinically meaningful activity in heavily pretreated patients with AKT1 E17K-mutant ER+ MBC, including those with prior disease progression on fulvestrant. Tolerability and activity appeared improved by the combination.

Eribulin Synergistically Increases Anti-Tumor Activity of an mTOR Inhibitor by Inhibiting pAKT/pS6K/pS6 in Triple Negative Breast Cancer

Unlike other breast cancer subtypes, patients with triple negative breast cancer (TNBC) have poor outcomes and no effective targeted therapies, leaving an unmet need for therapeutic targets. Efforts to profile these tumors have revealed the PI3K/AKT/mTOR pathway as a potential target. Activation of this pathway also contributes to resistance to anti-cancer agents, including microtubule-targeting agents. Eribulin is one such microtubule-targeting agent that is beneficial in treating taxane and anthracycline refractory breast cancer. In this study, we compared the effect of eribulin on the PI3K/AKT/mTOR pathway with other microtubule-targeting agents in TNBC. We found that the phosphorylation of AKT was suppressed by eribulin, a microtubule depolymerizing agent, but activated by paclitaxel, a microtubule stabilizing agent. The combination of eribulin and everolimus, an mTOR inhibitor, resulted in an increased reduction of p-S6K1 and p-S6, a synergistic inhibition of cell survival in vitro, and an enhanced suppression of tumor growth in two orthotopic mouse models. These findings provide a preclinical foundation for targeting both the microtubule cytoskeleton and the PI3K/AKT/mTOR pathway in the treatment of refractory TNBC.

Combined Inhibition of STAT3 and DNA Repair in Palbociclib-Resistant ER-Positive Breast Cancer

PURPOSE

Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are currently used in combination with endocrine therapy to treat advanced hormone receptor-positive, HER2-negative breast cancer. Although this treatment doubles time to progression compared with endocrine therapy alone, about 25%-35% of patients do not respond, and almost all patients eventually acquire resistance. Discerning the mechanisms of resistance to CDK4/6 inhibition is crucial in devising alternative treatment strategies.

EXPERIMENTAL DESIGN

Palbociclib-resistant cells (MCF-7 and T47D) were generated in a step-wise dose-escalading fashion. Whole-exome sequencing, genome-wide expression analysis, and proteomic analysis were performed in both resistant and parental (sensitive) cells. Pathway alteration was assessed mechanistically and pharmacologically. Biomarkers of altered pathways were examined in tumor samples from patients with palbociclib-treated breast cancer whose disease progressed while on treatment.

RESULTS

Palbociclib-resistant cells are cross-resistant to other CDK4/6 inhibitors and are also resistant to endocrine therapy (estrogen receptor downregulation). IL6/STAT3 pathway is induced, whereas DNA repair and estrogen receptor pathways are downregulated in the resistant cells. Combined inhibition of STAT3 and PARP significantly increased cell death in the resistant cells. Matched tumor samples from patients with breast cancer who progressed on palbociclib were examined for deregulation of estrogen receptor, DNA repair, and IL6/STAT3 signaling, and results revealed that these pathways are all altered as compared with the pretreatment tumor samples.

CONCLUSIONS

Palbociclib resistance induces endocrine resistance, estrogen receptor downregulation, and alteration of IL6/STAT3 and DNA damage response pathways in cell lines and patient samples. Targeting IL6/STAT3 activity and DNA repair deficiency using a specific STAT3 inhibitor combined with a PARP inhibitor could effectively treat acquired resistance to palbociclib.

Endocrine and Targeted Therapy for Hormone-Receptor-Positive, HER2-Negative Advanced Breast Cancer: Insights to Sequencing Treatment and Overcoming Resistance Based on Clinical Trials

Background: Advanced hormone-receptor positive HER2 negative breast cancer is a common and a very heterogeneous disease. Hormone therapy is the main first line treatment of choice, given alone or in combination with other agents that have shown to improve patient outcomes, Nevertheless, treatment remains generally palliative rather than curative. Sequencing of such treatment remains challenging, especially with resurgence of variable resistance patterns. Multiple attempts have been made to overcome resistance and improve patient survival, yet resistance remains not very well understood and metastatic cancer remains a disease with dismal prognosis.

Methods: In this paper, we searched pubmed database as well as local and international meetings for all studies discussing advanced and metastatic hormone-receptor-positive, her2-negative breast cancer, hormonal treatment, resistance to hormonal treatment, mechanism of resistance, and means to overcome such resistance.

Conclusion: There does not exist an optimal treatment sequence for hormone-receptor-positive, her2-negative advanced breast cancer. However, after review of literature, a reasonable approach may be starting with tamoxifen, aromatase inhibitors, or fulvestrant in absence of visceral crisis, in addition to ensuring adequate ovarian function suppression in pre/peri-menopausal women. Aromatase inhibitors and fulvestrant seem to be superior. Resistance to such agents is increasing, mostly attributed to genetic and molecular changes. Multiple modalities are addressed to overcome such resistance including use of CKD4/6 inhibitors, mTOR inhibitors and PI3K inhibitors in addition to other agents under study, all with promising results. CDK4/6 inhibitors work best when used in frontline setting. Finally, treatment of breast cancer remains a growing field, and more studies are to be awaited.

Metastatic bone disease: Pathogenesis and therapeutic options: Up-date on bone metastasis management

Bone metastases (BM) are a common complication of cancer, whose management often requires a multidisciplinary approach. Despite the recent therapeutic advances, patients with BM may still experience skeletal-related events and symptomatic skeletal events, with detrimental impact on quality of life and survival. A deeper knowledge of the mechanisms underlying the onset of lytic and sclerotic BM has been acquired in the last decades, leading to the development of bone-targeting agents (BTA), mainly represented by anti-resorptive drugs and bone-seeking radiopharmaceuticals. Recent pre-clinical and clinical studies have showed promising effects of novel agents, whose safety and efficacy need to be confirmed by prospective clinical trials. Among BTA, adjuvant bisphosphonates have also been shown to reduce the risk of BM in selected breast cancer patients, but failed to reduce the incidence of BM from lung and prostate cancer. Moreover, adjuvant denosumab did not improve BM free survival in patients with breast cancer, suggesting the need for further investigation to clarify BTA role in early-stage malignancies. The aim of this review is to describe BM pathogenesis and current treatment options in different clinical settings, as well as to explore the mechanism of action of novel potential therapeutic agents for which further investigation is needed.

Everolimus inhibits breast cancer cell growth through PI3K/AKT/mTOR signaling pathway

Breast cancer is one of the most prevalent malignancies and the leading cause of cancer‑associated mortality in women worldwide and in China. Everolimus (C53H83NO14) is an efficient anti-cancer drug for breast cancer which targets mammalian target of rapamycin (mTOR). The present study investigated the inhibitory effects of everolimus on breast cancer cells and an MCF‑7‑bearing mouse model. The potential mechanism of the everolimus‑mediated decrease in growth and aggressiveness of breast cancer cells was reported. Results demonstrated that everolimus significantly inhibited breast cancer cell growth, migration and invasion. It was demonstrated that everolimus induced apoptosis through decreasing B cell lymphoma (Bcl)‑2 and Bcl‑w and increasing caspase‑3 and caspase‑8 expression levels in breast cancer cells. It was observed that everolimus decreased phosphoinositide 3‑kinase (PI3K), protein kinase B (AKT) and mTOR expression levels in breast cancer cells. Results additionally demonstrated that PI3 K overexpression prevented that everolimus‑mediated inhibition of growth and aggressiveness in MCF‑7 cells. In vivo assays demonstrated that everolimus treatment markedly inhibited tumor growth in the MCF‑7 bearing mouse model. Overall, these data indicate that everolimus inhibits growth and aggressiveness of breast cancer cells through the PI3K/AKT/mTOR signaling pathways, suggesting the PI3K/AKT/mTOR signaling pathway may act as a therapeutic target for the treatment of human cancer.

Raptor mediates the antiproliferation of cardamonin by mTORC1 inhibition in SKOV3 cells

Purpose

Cardamonin inhibits the proliferation of SKOV3 cells by suppressing the mammalian target of rapamycin complex 1 (mTORC1). However, the mechanism of cardamonin on mTORC1 inhibition has not been well demonstrated. The regulatory-associated protein of TOR (Raptor) is an essential component of mTORC1. Here, we investigated the role of Raptor in the mTORC1 inhibition effect of cardamonin in SKOV3 cells.

Methods

The expression of Raptor was knockdown by small interfering RNA (siRNA). The expressions of specific binding proteins of mTORC1 were analyzed by Western blotting, and the cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay.

Results

Rapamycin, AZD8055, and cardamonin inhibited the activity of mammalian target of rapamycin (mTOR). Different from rapamycin and AZD8055, cardamonin suppressed the phosphorylation and protein expression of Raptor. Transfected with Raptor siRNA, the mTOR activation and proliferation of SKOV3 cells were decreased, and these effects were strengthened by cardamonin in Raptor siRNA SKOV3 cells. Cardamonin interfered with the lysosomal colocalization of mTOR with lysosomal associated membrane protein 2 (LAMP2), which was also hindered by Raptor siRNA. Furthermore, cardamonin strengthened the inhibitory effect on the lysosomal localization of mTOR in Raptor siRNA cells.

Conclusion

Our results suggested that Raptor mainly mediated the inhibition of cardamonin on mTORC1 in SKOV3 cells.

Bone-Targeted Therapies in Cancer-Induced Bone Disease

Cancer-induced bone disease is a major source of morbidity and mortality in cancer patients. Thus, effective bone-targeted therapies are essential to improve disease-free, overall survival and quality of life of cancer patients with bone metastases. Depending of the cancer-type, bone metastases mainly involve the modulation of osteoclast and/or osteoblast activity by tumour cells. To inhibit metastatic bone disease effectively, it is imperative to understand its underlying mechanisms and identify the target cells for therapy. If the aim is to prevent bone metastasis, it is essential to target not only bone metastatic features in the tumour cells, but also tumour-nurturing bone microenvironment properties. The currently available bone-targeted agents mainly affect osteoclasts, inhibiting bone resorption (e.g. bisphosphonates, denosumab). Some agents targeting osteoblasts begin to emerge which target osteoblasts (e.g. romosozumab), activating bone formation. Moreover, certain drugs initially thought to target only osteoclasts are now known to have a dual action (activating osteoblasts and inhibiting osteoclasts, e.g. proteasome inhibitors). This review will focus on the evolution of bone-targeted therapies for the treatment of cancer-induced bone disease, summarizing preclinical and clinical findings obtained with anti-resorptive and bone anabolic therapies.

Dosing time dependent in vitro pharmacodynamics of Everolimus despite a defective circadian clock

Everolimus (EV), a rapamycin analogue mTOR inhibitor, is used in the clinic to treat Estrogen positive (ER+) breast cancer in order to avoid the resistance to hormonotherapy. Here, we investigated whether EV efficacy varied according to administration timing by using the ER+ breast cancer cell line MCF-7 as model system. Our results showed that instead of apoptosis, EV induced a G0/G1 phase blockage of MCF-7 cells. Following serum shock, MCF-7 cells displayed a statistically significant 24h rhythm of mammalian target of Rapamycin (mTOR) activity, but perturbed circadian clock genes oscillations. Interestingly, the different delivery schedule of EV presented different efficacy in G0/G1 phase blockage in serum shocked MCF-7 cells. Moreover, serum shock induced also a circadian-like oscillation in expression or activity of several important G1 phase progression proteins, such as Cyclin D1 and phosphorylated Retinoblastoma protein (RB). Inhibition mTOR activity by EV reduced Cyclin D1 and Cyclin D3 protein level as well as RB phosphorylation level. Taken together, the results indicated that serum shock synchronization induced a circadian oscillation in mTOR activity in MCF-7 cells, which rhythmically regulated the synthesis or phosphorylation of key G1 progression proteins, such as Cyclin D1 and phosphorylated RB, ultimately resulting in different G0/G1 blockage efficiency according to different EV administration timing.

Preclinical validation of a novel compound targeting p70S6 kinase in breast cancer

Breast cancer is a frequent and treatable disease. However, when recurrent, breast cancer often becomes refractory to therapy and progresses into metastatic forms that are typically incurable. Thus, understanding and targeting the critical pathways underlying breast cancer recurrence is urgently needed to eradicate primary disease and achieve better prognosis. Recently, we have demonstrated that the ribosomal protein p70S6K is activated in residual breast cancer cells as a result of post-surgical inflammation and that interfering with its activity in the peri-operative setting strongly suppresses recurrence in a mouse model. In order to develop clinically-exploitable treatments targeting p70S6K, we have tested a newly generated compound, called FS-115. FS-115 potently inhibited p70S6K1 (IC50 35nM) with high selectivity over other AGC kinases or PI3K pathway kinases. In vitro, treatment with FS-115 efficiently blocked p70S6K activity in breast cancer cell lines and impaired colony formation and anchorage independent growth. Pharmacokinetic profiling showed that FS-115 exhibited high oral bioavailability, optimal plasma distribution and high brain penetrance. In nude mice, FS-115 strongly suppressed tumor take-rate and primary tumor growth. Oral dosing with FS-115 in a peri-operative schedule was effective in decreasing local recurrence of breast cancer and a long-term treatment schedule was well tolerated and efficiently suppressed distant metastasis formation. Altogether, we propose that FS-115 might be a good candidate for the treatment of breast cancer patients at high risk to relapse.

SUMMARY STATEMENT

Our results confirm that inhibition of p70S6K represents a valuable opportunity for restraining loco-regional relapse and metastasis in breast cancer and identify in FS-115 a promising candidate-inhibitor to move from preclinical to clinical treatments.

Exploring Polypharmacology in Drug Discovery and Repurposing Using the CANDO Platform

BACKGROUND

Traditional drug discovery approaches focus on a limited set of target molecules for treatment against specific indications/diseases. However, drug absorption, dispersion, metabolism, and excretion (ADME) involve interactions with multiple protein systems. Drugs approved for particular indication(s) may be repurposed as novel therapeutics for others. The severely declining rate of discovery and increasing costs of new drugs illustrate the limitations of the traditional reductionist paradigm in drug discovery.

METHODS

We developed the Computational Analysis of Novel Drug Opportunities (CANDO) platform based on a hypothesis that drugs function by interacting with multiple protein targets to create a molecular interaction signature that can be exploited for therapeutic repurposing and discovery. We compiled a library of compounds that are human ingestible with minimal side effects, followed by an 'all-compounds' vs 'all-proteins' fragment-based multitarget docking with dynamics screen to construct compound-proteome interaction matrices that were then analyzed to determine similarity of drug behavior. The proteomic signature similarity of drugs is then ranked to make putative drug predictions for all indications in a shotgun manner.

RESULTS

We have previously applied this platform with success in both retrospective benchmarking and prospective validation, and to understand the effect of druggable protein classes on repurposing accuracy. Here we use the CANDO platform to analyze and determine the contribution of multitargeting (polypharmacology) to drug repurposing benchmarking accuracy. Taken together with the previous work, our results indicate that a large number of protein structures with diverse fold space and a specific polypharmacological interactome is necessary for accurate drug predictions using our proteomic and evolutionary drug discovery and repurposing platform.

CONCLUSION

These results have implications for future drug development and repurposing in the context of polypharmacology.

Phosphatidylinositol-3 Kinase Inhibitors, Buparlisib and Alpelisib, Sensitize Estrogen Receptor-positive Breast Cancer Cells to Tamoxifen

Tamoxifen is the standard first-line hormonal therapy for premenopausal women with estrogen receptor (ER)-positive metastatic breast cancer (BC). One of the crucial mechanisms underlying hormonal therapy resistance is the collateral activation of the phosphatidylinositol-3 kinase (PI3K)/AKT pathway. We explored whether PI3K inhibitors, buparlisib and alpelisib, enhance the efficacy of tamoxifen against ER-positive BC cells. We have observed a synergism between alpelisib or buparlisib and tamoxifen in the treatment for ER-positive BC cell lines harboring different PI3K alterations. Immunoblotting analysis showed alpelisib, buparlisib, or either drug in combination with tamoxifen downregulated the PI3K downstream targets in the MCF-7 and ZR75-1 cells. In the MCF-7 cells transfected with a constitutive active (myristoylated) AKT1 construct or mutant ER, the synergistic effect between alpelisib and tamoxifen was markedly attenuated, indicating that synergism depends on AKT inhibition or normally functioning ER. Combining alpelisib or buparlisib with tamoxifen also attenuated MCF-7 tumor growth in Balb/c nude mice. Our data suggest that additional PI3K blockade might be effective in enhancing the therapeutic effect of tamoxifen in ER-positive BC and support the rationale combination in clinical trials.

The Therapeutic Potential of PI3K/Akt/mTOR Inhibitors in Breast Cancer: Rational and Progress

Breast cancer (BC) is the most commonly diagnosed cancer in women. The PI3K/AKT/mTOR pathway is among the most frequently dysregulated pathways in patients with BC. The activation of this pathway is associated with increased cell growth and clinical outcome, and its overexpression is associated with a poor prognosis. It has been proposed that it may be of importance as a potential therapeutic target in the treatment of BC. The aim of current review is to provide an overview of the potential utility of PI3K/Akt/mTOR inhibitors in patients with BC, with particular emphasis on recent preclinical and clinical studies. J. Cell. Biochem. 119: 213-222, 2018. © 2017 Wiley Periodicals, Inc.

Dose intensity and efficacy of the combination of everolimus and exemestane (EVE/EXE) in a real-world population of hormone receptor-positive (ER+/PgR+), HER2-negative advanced breast cancer (ABC) patients: a multicenter Italian experience

AIM

This retrospective analysis focused on the effect of treatment with EVE/EXE in a real-world population outside of clinical trials. We examined the efficacy of this combination in terms of PFS and RR related to dose intensity (5 mg daily versus 10 mg daily) and tolerability.

METHODS

163 HER2-negative ER+/PgR+ ABC patients, treated with EVE/EXE from May 2011 to March 2016, were included in the analysis. The primary endpoints were the correlation between the daily dose and RR and PFS, as well as an evaluation of the tolerability of the combination. Secondary endpoints were RR, PFS, and OS according to the line of treatment. Patients were classified into three different groups, each with a different dose intensity of everolimus (A, B, C).

RESULTS

RR was 29.8% (A), 27.8% (B) (p = 0.953), and not evaluable (C). PFS was 9 months (95% CI 7-11) (A), 10 months (95% CI 9-11) (B), and 5 months (95% CI 2-8) (C), p = 0.956. OS was 38 months (95% CI 24-38) (A), median not reached (B), and 13 months (95% CI 10-25) (C), p = 0.002. Adverse events were stomatitis 57.7% (11.0% grade 3-4), asthenia 46.0% (6.1% grade 3-4), hypercholesterolemia 46.0% (0.6% grade 3-4), and hyperglycemia 35.6% (5.5% grade 3-4). The main reason for discontinuation/interruption was grade 2-3 stomatitis.

CONCLUSIONS

No correlation was found between dose intensity (5 vs. 10 mg labeled dose) and efficacy in terms of RR and PFS. The tolerability of the higher dose was poor in our experience, although this had no impact on efficacy.

Cooperative Targets of Combined mTOR/HDAC Inhibition Promote MYC Degradation

Cancer treatments often require combinations of molecularly targeted agents to be effective. mTORi (rapamycin) and HDACi (MS-275/entinostat) inhibitors have been shown to be effective in limiting tumor growth, and here we define part of the cooperative action of this drug combination. More than 60 human cancer cell lines responded synergistically (CI<1) when treated with this drug combination compared with single agents. In addition, a breast cancer patient-derived xenograft, and a BCL-XL plasmacytoma mouse model both showed enhanced responses to the combination compared with single agents. Mice bearing plasma cell tumors lived an average of 70 days longer on combination treatment compared with single agents. A set of 37 genes cooperatively affected (34 downregulated; 3 upregulated) by the combination responded pharmacodynamically in human myeloma cell lines, xenografts, and a P493 model, and were both enriched in tumors, and correlated with prognostic markers in myeloma patient datasets. Genes downregulated by the combination were overexpressed in several untreated cancers (breast, lung, colon, sarcoma, head and neck, myeloma) compared with normal tissues. The MYC/E2F axis, identified by upstream regulator analyses and validated by immunoblots, was significantly inhibited by the drug combination in several myeloma cell lines. Furthermore, 88% of the 34 genes downregulated have MYC-binding sites in their promoters, and the drug combination cooperatively reduced MYC half-life by 55% and increased degradation. Cells with MYC mutations were refractory to the combination. Thus, integrative approaches to understand drug synergy identified a clinically actionable strategy to inhibit MYC/E2F activity and tumor cell growth in vivoMol Cancer Ther; 16(9); 2008-21. ©2017 AACR.

Role of everolimus in the treatment of metastatic HER2-negative/HR-positive breast cancer

Metastatic breast cancer (mBC) is a leading cause of mortality for women around the world. The response to hormonotherapy of the patients with HER2-negative/HR-positive mBC is usually limited, and many strategies are in place to contrast the hormonotherapy resistance. Since efficacy and effectiveness of everolimus have been established by many trials, this review is aimed to give a structured synthesis to define the everolimus clinical role among the treatment options for mBC. Key aspects of everolimus dosing and safety profile, drawn up by relevant findings, are included, as well as the role of biomarkers to identify subgroups of mBC patients who may best benefit from everolimus treatment.

Long-term complete response in a breast cancer patient with skeletal muscle metastases diagnosed using 18F-FDG-PET

Common sites for metastatic spreading from breast cancer are bones, lungs and liver, the skeletal muscle being an unusual site. Although rare, when skeletal muscle metastases occur they are associated with a poor prognosis. These metastases are clinically difficult to diagnose since they can be found without pain symptoms. Radiologically, magnetic resonance imaging has been considered better than computed tomography for imaging of the muscles and has been the first procedure to use in case of muscle metastasis suspicion. In the last years, positron emission tomography (PET) with 18Fluorine-2-fluoro-2-deoxy-d-glucose (18F-FDG) has emerged as the main imaging tool. We here report a case of a hormone receptor-positive/human epidermal growth factor receptor 2-negative patient who presented with a recurrent infiltrating ductal carcinoma and diffuse skeletal muscle metastases detected by 18F-FDG-PET. The treatment of the patient with exemestane and everolimus led to a durable complete response.

Enhancing Endocrine Therapy Combination Strategies for the Treatment of Postmenopausal HR+/HER2- Advanced Breast Cancer

Breast cancer (BC) is the most common malignancy in women worldwide, with approximately two-thirds having hormone receptor-positive (HR+) tumors. New endocrine therapy (ET) strategies include combining ET agents as well as adding inhibitors targeting growth factors, angiogenesis, the mechanistic target of rapamycin, phosphoinositide 3-kinase (PI3K), or cyclin-dependent kinase 4/6 to ET. Level 1 evidence supports use of fulvestrant plus anastrozole or palbociclib plus letrozole as first-line therapy for HR+/HER- advanced BC with special consideration for the former in ET-naïve patients, as well as everolimus plus exemestane or palbociclib plus fulvestrant as second-line therapy with special consideration in select first-line patients. Although the safety profiles of these combinations are generally predictable and manageable, both everolimus and palbociclib are associated with an increased risk of potentially serious or early-onset toxicities requiring individualized a priori adverse event risk stratification, earlier and more rigorous agent-specific monitoring, and patient education. Although each of these combinations improves progression-free survival, none with the exception of anastrazole plus fulvestrant have demonstrated improved overall survival. PI3K catalytic-α mutations assessed from circulating tumor DNA represent the first potentially viable serum biomarker for the selection of ET combinations, and new data demonstrate the feasibility of this minimally invasive technique as an alternative to traditional tissue analysis. Therapeutic ratios of select ET combinations support their use in first- and second-line settings, but optimal sequencing has yet to be determined.

THE ONCOLOGIST

2017;22:12-24 IMPLICATIONS FOR PRACTICE: Emerging data show that new endocrine therapy (ET) combinations can improve progression-free and overall survival outcomes in patients with hormone receptor-positive, HER2-negative (HR+/HER-) advanced breast cancer. Level 1 evidence supports consideration of dual ET regimens, particularly in ET-naïve patients, or palbociclib plus letrozole as first-line therapy, as well as the addition of mTOR or CDK4/6 inhibitors to established ET in the second-line setting and in select first-line patients. Some combinations are associated with increased risk of class-specific toxicities that will require individualized risk stratification, earlier and more rigorous agent-specific monitoring, and patient education. Recent data on a noninvasive biomarker assay that predicts response to a phosphoinositide 3-kinase inhibitor demonstrates the feasibility of this minimally invasive technique as an alternative to traditional tissue analysis.

Unravelling exemestane: From biology to clinical prospects

Aromatase inhibitors (AIs) are anti-tumor agents used in clinic to treat hormone-dependent breast cancer. AIs block estrogens biosynthesis by inhibiting the enzyme aromatase, preventing tumor progression. Exemestane, a third-generation steroidal AI, belongs to this class of drugs and is currently used in clinic to treat postmenopausal women, due to its high efficacy and good tolerability. Here, its pharmacological and biological aspects as well as its clinical applications and comparison to other endocrine therapeutic agents, are reviewed. It is also focused the benefits and risks of exemestane, drawbacks to be overcome and aspects to be explored.

CE: A Review of Common Oral Treatments for Breast Cancer: Improving Patient Safety in Nononcology Settings

: Breast cancer patients are living longer with the disease than ever before. According to the National Cancer Institute, more than 3 million women in the United States are currently living with a breast cancer diagnosis, and many seek care in nononcology settings, whether for treatment, acute symptoms and complaints related to their cancer diagnosis, or unrelated concerns. Yet many nononcology providers are unfamiliar with the various oral agents used to treat breast cancer, and their possible adverse effects and drug interactions. It is imperative that all providers be aware of these agents and know when a patient is currently taking or has taken them. This article provides an overview of the most common oral treatments for breast cancer and discusses common adverse effects and management.

Clinical Implications of the Progression-Free Survival Endpoint for Treatment of Hormone Receptor-Positive Advanced Breast Cancer

: Hormonal therapy for advanced breast cancer (ABC) has evolved significantly since the introduction of tamoxifen more than 40 years ago. The availability of selective antiestrogen therapies has further improved treatment options for women with hormone receptor-positive (HR+) ABC. However, with the development of resistance to hormonal therapies, a new treatment paradigm has emerged based on our understanding of biological pathways involved in HR+ breast cancer and mechanisms of resistance to hormonal therapy. Recent drug development efforts have focused on combining hormonal treatment with agents that target mammalian target of rapamycin serine-threonine kinases and cyclin-dependent kinases. In parallel with the evolution of hormonal and targeted therapies, our understanding of the utility of clinical endpoints has deepened. Progression-free survival (PFS) is a primary endpoint well-understood by clinicians and is increasingly accepted as a surrogate for overall survival (OS) by the U.S. Food and Drug Administration. Yet the perceived clinical benefit of PFS to patients is less well understood. Patients may not grasp the implications of prolonged PFS, highlighting the reality that patient preference in treatment selection encompasses factors that extend beyond drug activity. This presents an opportunity for clinicians to discuss PFS with patients in the context of their treatment plans, clinical outcomes, and quality-of-life measures. The objective of this review is to explore the clinical validity of the PFS and OS endpoints and the clinical relevance of PFS and OS to patients, especially in light of drivers that led to a range of treatment options for patients with HR+ ABC.

IMPLICATIONS FOR PRACTICE

Advances in drug development during the past two decades have provided numerous options for treatment of advanced breast cancer that include monotherapy with endocrine modulating agents and dual therapy that combines endocrine therapy with an inhibitor targeting the mammalian target of rapamycin serine-threonine kinase or cyclin-dependent kinase pathways known to be involved with resistance. Clinical trial endpoints for breast cancer have evolved as well. Communication of progression-free survival, overall survival, and other outcomes with patients should incorporate the context of the individual's treatment plan and include discussion of response rate, side effects, and quality of life.

The therapeutic potential of mTOR inhibitors in breast cancer

Rapamycin and modified rapamycins (rapalogs) have been used to prevent allograft rejection after organ transplant for over 15 years. The mechanistic target of rapamycin (mTOR) has been determined to be a key component of the mTORC1 complex which consists of the serine/threonine kinase TOR and at least five other proteins which are involved in regulating its activity. Some of the best characterized substrates of mTORC1 are proteins which are key kinases involved in the regulation of cell growth (e.g., p70S6K) and protein translation (e.g., 4E-BP1). These proteins may in some cases serve as indicators to sensitivity to rapamycin-related therapies. Dysregulation of mTORC1 activity frequently occurs due to mutations at, or amplifications of, upstream growth factor receptors (e.g., human epidermal growth factor receptor-2, HER2) as well as kinases (e.g., PI3K) and phosphatases (e.g., PTEN) critical in the regulation of cell growth. More recently, it has been shown that certain rapalogs may enhance the effectiveness of hormonal-based therapies for breast cancer patients who have become resistant to endocrine therapy. The combined treatment of certain rapalogs (e.g., everolimus) and aromatase inhibitors (e.g., exemestane) has been approved by the United States Food and Drug Administration (US FDA) and other drug regulatory agencies to treat estrogen receptor positive (ER+) breast cancer patients who have become resistant to hormonal-based therapies and have progressed. This review will summarize recent basic and clinical research in the area and evaluate potential novel therapeutic approaches.

Hormone receptor positive, HER2 negative metastatic breast cancer: Future treatment landscape

Endocrine therapy is an established and effective treatment strategy for hormone receptor positive metastatic breast cancer. The clinical utility of endocrine therapy is lost over time due to evolving changes in tumor biology and the development of endocrine resistance. Many agents targeting the intracellular signaling pathways associated with endocrine resistance are in development. Encouraging early results have been seen for agents which directly target the estrogen receptor (ER), inhibitors of co-signaling pathways, inhibitors of ER chaperones, ER antagonists able to inhibit mutated or otherwise activated ERs, and modulators of histone acetylation restoring synthesis of ER signaling components. Following our systematic review of treatments with established benefits in this supplement, we review some of the more promising new strategies for overcoming endocrine resistance, looking at the impact on disease control and quality of life for women with hormone receptor positive, HER2 negative breast cancer. We also examine the biomarkers that may guide selection of the best therapy for the individual.

Drug Eluting Stents for Malignant Airway Obstruction: A Critical Review of the Literature

Lung cancer being the most prevalent malignancy in men and the 3(rd) most frequent in women is still associated with dismal prognosis due to advanced disease at the time of diagnosis. Novel targeted therapies are already on the market and several others are under investigation. However non-specific cytotoxic agents still remain the cornerstone of treatment for many patients. Central airways stenosis or obstruction may often complicate and decrease quality of life and survival of these patients. Interventional pulmonology modalities (mainly debulking and stent placement) can alleviate symptoms related to airways stenosis and improve the quality of life of patients. Mitomycin C and sirolimus have been observed to assist a successful stent placement by reducing granuloma tissue formation. Additionally, these drugs enhance the normal tissue ability against cancer cell infiltration. In this mini review we will concentrate on mitomycin C and sirolimus and their use in stent placement.

Incidence and clinical significance of ESR1 mutations in heavily pretreated metastatic breast cancer patients

BACKGROUND

ESR1 mutation has recently emerged as one of the important mechanisms involved in endocrine resistance. The incidence and clinical implication of ESR1 mutation has not been well evaluated in heavily pretreated breast cancer patients.

METHODS

We conducted a retrospective review of advanced breast cancer patients with tumors who underwent next-generation sequencing genomic profiling using Foundation One test at Cancer Treatment Centers of America(®) regional hospitals between November 2012 and November 2014.

RESULTS

We identified a total of 341 patients including 217 (59%) estrogen receptor (ER)+, 177 (48%) progesterone receptor (PR)+, 30 (8%) hormone receptor+/HER2 positive, and 119 (32%) triple negative patients. ESR1 mutation was noted in 27/222 (12.1%) ER+ or PR+ breast cancer patients. All ER+ patients received at least one line of an aromatase inhibitor. All 28 patients were found to harbor ESR1 mutations affecting ligand-binding domain with the most common mutations affecting Y537 (17/28, 60.7%) and D538 (9/28, 32.1%). In this cohort, 19 (67.9%) patients carried three or more, seven (25%) patients had one or two additional genomic alterations and one (3.6%) patient had an ESR1 mutation only. Of 28 patients, three patients were treated with fulvestrant immediately before and two patients were treated after next-generation sequencing testing; only one patient achieved stable disease for 8 months and the other four patients had progression of disease. In all, 3/3 (100%) patients before testing and 2/4 (50%) after testing treated with exemestane and everolimus achieved stable disease for at least 6 months.

CONCLUSION

ESR1 mutation was found in 12.1% of a large cohort of advanced breast cancer patients. Exemestane in combination with everolimus might be a reasonable option. Prospective studies are warranted to validate these findings.

Everolimus restrains the paracrine pro-osteoclast activity of breast cancer cells

Background

Breast cancer (BC) cells secrete soluble factors that accelerate osteoclast (OC) differentiation, leading to the formation of osteolytic bone metastases. In the BOLERO-2 trial, BC patients with bone involvement who received Everolimus had a delayed tumor progression in the skeleton as a result of direct OC suppression through the inhibition of mTOR, in addition to the general suppressor effect on the cancer cells. Here, we explored the effect of Everolimus, as mTOR inhibitor, on the pro-OC paracrine activity of BC cells.

Methods

Both MDA-MB-231 and MCF-7 BC cell lines were incubated with sub-lethal amounts of Everolimus, and their conditioned supernatants were assessed for their capacity to differentiate OCs from PBMC from healthy donors, as well as to interfere with their bone resorbing activity shown on calcium phosphate slices. We also measured the mRNA levels of major pro-OC factors in Everolimus-treated BC cells and their secreted levels by ELISA, and evaluated by immunoblotting the phosphorylation of transcription factors enrolled by pathways cooperating with the mTOR inhibition. Finally, the in vivo pro-OC activity of these cells was assessed in SCID mice after intra-tibial injections.

Results

We found that Everolimus significantly inhibited the differentiation of OCs and their in vitro bone-resorbing activity, and also found decreases of both mRNA and secreted pro-OC factors such as M-CSF, IL-6, and IL-1β, whose lower ELISA levels paralleled the defective phosphorylation of NFkB pathway effectors. Moreover, when intra-tibially injected in SCID mice, Everolimus-treated BC cells produced smaller bone metastases than the untreated cells.

Conclusions

mTOR inhibition in BC cells leads to a suppression of their paracrine pro-OC activity by interfering with the NFkB pathway; this effect may also account for the delayed progression of bone metastatic disease observed in the BOLERO-2 trial.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1717-8) contains supplementary material, which is available to authorized users.

The PI3K/AKT Pathway as a Target for Cancer Treatment

Anticancer targeted therapies are designed to exploit a particular vulnerability in the tumor, which in most cases results from its dependence on an oncogene and/or loss of a tumor suppressor. Genes in the phosphoinositide 3-kinase (PI3K)/AKT pathway are the most frequently altered in human cancers. Aberrant activation of this pathway, as a result of these somatic alterations, is associated with cellular transformation, tumorigenesis, cancer progression, and drug resistance. Several drugs targeting PI3K/ATK are currently in clinical trials, alone or in combination, in both solid tumors and hematologic malignancies. These drugs are the focus of this review.

Prognostic significance of PD-L1 and PD-L2 in breast cancer

PD-L1 and PD-L2 constitute an important antitumor immune response. In breast cancer, their prognostic value is still to be defined. In this study, we investigate the correlation between PD-L1 and PD-L2 protein expressions with clinical and pathologic features and disease-free survival and overall survival. To assess PD-L1 and PD-L2 expressions, we conducted immunohistochemistry studies using a breast cancer tissue microarray encompassing a total of 192 breast cancer cases, stages I, II, and III, with detailed clinical and outcome data. PD-L1 expression was present in 56.6% (107/189), and PD-L2 expression was identified in 50.8% (97/191) of breast cancer cases. Younger age at diagnosis, lymph node positivity, negative estrogen receptor, and recurrence at distant sites were all associated with both PD-L1 and PD-L2 expressions. The presence of larger tumors was associated only with PD-L1 expression. In our study, PD-L1 expression was significantly associated with better overall survival (P = .04) in breast cancer patients. Despite its association with poor clinical and pathologic features, PD-L1 expression emerges as a positive prognostic biomarker in breast cancer. This survival result might be due to the presence of a strong antitumor immune response leading to PD-L1 expression.