Showing papers on "Lapatinib published in 2018"
TL;DR: This review focuses on HER3-mediated signaling, its role in drug resistance and the latest advances to overcome resistance by targeting HER3 using mono- and bispecific antibodies and small molecule inhibitors.
Abstract: ERBB family members including epidermal growth factor receptor (EGFR) also known as HER1, ERBB2/HER2/Neu, ERBB3/HER3 and ERBB4/HER4 are aberrantly activated in multiple cancers and hence serve as drug targets and biomarkers in modern precision therapy. The therapeutic potential of HER3 has long been underappreciated, due to impaired kinase activity and relatively low expression in tumors. However, HER3 has received attention in recent years as it is a crucial heterodimeric partner for other EGFR family members and has the potential to regulate EGFR/HER2-mediated resistance. Upregulation of HER3 is associated with several malignancies where it fosters tumor progression via interaction with different receptor tyrosine kinases (RTKs). Studies also implicate HER3 contributing significantly to treatment failure, mostly through the activation of PI3K/AKT, MAPK/ERK and JAK/STAT pathways. Moreover, activating mutations in HER3 have highlighted the role of HER3 as a direct therapeutic target. Therapeutic targeting of HER3 includes abrogating its dimerization partners' kinase activity using small molecule inhibitors (lapatinib, erlotinib, gefitinib, afatinib, neratinib) or direct targeting of its extracellular domain. In this review, we focus on HER3-mediated signaling, its role in drug resistance and discuss the latest advances to overcome resistance by targeting HER3 using mono- and bispecific antibodies and small molecule inhibitors.
122 citations
TL;DR: The results suggest that standardized cannabis drug preparations, rather than pure cannabinoids, could be considered as part of the therapeutic armamentarium to manage breast cancer.
108 citations
TL;DR: Despite significant research efforts, including translational efforts and new imaging techniques, no predictive biomarkers have been clinically validated and therefore a more refined approach to treatment tailoring remains beyond the authors' reach.
107 citations
TL;DR: New strategies in development to treat HER2-positive metastatic breast cancer referring to the mechanisms of action of new drugs and new combinations including results reported so far are examined.
85 citations
TL;DR: Recommendations agree that routine monitoring via methods such as electroencephalogram, cardiac biomarkers, and blood pressure is warranted during the course of treatment, in addition to a comprehensive collection of past medical history and risk factors to identify those at heightened risk for cardiovascular events.
Abstract: The tyrosine kinase inhibitor (TKI) drug class is a prominently used option in the treatment of various cancers. Safety evaluation of these drugs has shown evidence of cardiotoxicity of varying frequency and severity between agents; concern has led to updated labeling, warning prescribers of such. This review seeks to clarify the present dangers and investigate cardiotoxic mechanisms of action for each discussed TKI. Dasatinib was connected primarily with an incidence of fluid retention, edema, QT prolongation, and pulmonary hypertension in clinical studies. It is theorized that this is due to a combination of off-target kinase binding and on-target binding of Bcr-Abl, and less likely, mitochondrial induced apoptosis. Studies showed sorafenib to carry the risk of hypertension, QT prolongation, and myocardial infarction. Proposed mechanisms for these side effects include inhibition of proteins, vascular endothelium growth factor receptor, hERG potassium channels, and the RAF/MERK/ERK pro-survival pathway. Finally, lapatinib showed evidence of decreased left ventricular ejection fraction (LVEF) and QT prolongation in clinical studies. The literature attributes these as side effects of on-target ErbB2 binding leading to mitochondrial induced apoptosis. The concern warranted by these findings is in question. Pooled safety data suggest that the overall risk for cardiotoxicity is minimal in dasatinib and lapatinib. Sorafenib seems to carry a moderate concern. For the discussed agents, recommendations agree that routine monitoring via methods such as electroencephalogram, cardiac biomarkers, and blood pressure is warranted during the course of treatment, in addition to a comprehensive collection of past medical history and risk factors to identify those at heightened risk for cardiovascular events.
78 citations
TL;DR: This assay allows rapid determination of 19 TKI in less than 5min per run and will be useful to adjust doses of oral anticancer drugs in order to improve treatments efficacy.
74 citations
TL;DR: The present study showed that HER2+ GC patients respond differently according to concomitant genomic aberrations beyond ERBB2, high ER BB2 amplification by NGS or cfDNA can be a positive predictor for patient selection, and tumor genomic alterations change significantly during targeted agent therapy.
74 citations
TL;DR: PI3K pathway activation is associated with resistance to lapatinib and trastuzumab in breast cancers, without chemotherapy and further studies are warranted to investigate how to use these biomarkers to identify upfront patients who may respond to anti-HER2 alone,Without chemotherapy.
Abstract: Aberrant activation of the PI3K pathway has been implicated in resistance to HER2-targeted therapy, but results of clinical trials are confounded by the co-administration of chemotherapy. We investigated the effect of perturbations of this pathway in breast cancers from patients treated with neoadjuvant anti-HER2-targeted therapy without chemotherapy.
Baseline tumor samples from patients with HER2-positive breast cancer enrolled in TBCRC006 (NCT00548184), a 12-week neoadjuvant clinical trial with lapatinib plus trastuzumab [plus endocrine therapy for estrogen receptor (ER)-positive tumors], were assessed for PTEN status by immunohistochemistry and PIK3CA mutations by sequencing. Results were correlated with pathologic complete response (pCR). Of 64 evaluable patients, PTEN immunohistochemistry and PIK3CA mutation analysis were performed for 59 and 46 patients, respectively. PTEN status (dichotomized by H-score median) was correlated with pCR (32% in high PTEN vs. 9% in low PTEN, p = 0.04). PIK3CA mutations were identified in 14/46 tumors at baseline (30%) and did not correlate with ER or PTEN status. One patient whose tumor harbored a PIK3CA mutation achieved pCR (p = 0.14). When considered together (43 cases), 1/25 cases (4%) with a PIK3CA mutation and/or low PTEN expression levels had a pCR compared to 7/18 cases (39%) with wild-type PI3KCA and high PTEN expression levels (p = 0.006). PI3K pathway activation is associated with resistance to lapatinib and trastuzumab in breast cancers, without chemotherapy. Further studies are warranted to investigate how to use these biomarkers to identify upfront patients who may respond to anti-HER2 alone, without chemotherapy.
69 citations
TL;DR: Different mechanisms of resistance specific to each HER2+ subtype are suggested, including MET signaling for HER2E and HER2-HER3 heterodimerization for L-HER2+ cells.
Abstract: Extrinsic signals are implicated in breast cancer resistance to HER2-targeted tyrosine kinase inhibitors (TKIs). To examine how microenvironmental signals influence resistance, we monitored TKI-treated breast cancer cell lines grown on microenvironment microarrays composed of printed extracellular matrix proteins supplemented with soluble proteins. We tested ∼2,500 combinations of 56 soluble and 46 matrix microenvironmental proteins on basal-like HER2+ (HER2E) or luminal-like HER2+ (L-HER2+) cells treated with the TKIs lapatinib or neratinib. In HER2E cells, hepatocyte growth factor, a ligand for MET, induced resistance that could be reversed with crizotinib, an inhibitor of MET. In L-HER2+ cells, neuregulin1-β1 (NRG1β), a ligand for HER3, induced resistance that could be reversed with pertuzumab, an inhibitor of HER2-HER3 heterodimerization. The subtype-specific responses were also observed in 3D cultures and murine xenografts. These results, along with bioinformatic pathway analysis and siRNA knockdown experiments, suggest different mechanisms of resistance specific to each HER2+ subtype: MET signaling for HER2E and HER2-HER3 heterodimerization for L-HER2+ cells.
66 citations
TL;DR: This review discusses pivotal clinical trials that have shaped current clinical practices, the current consensus recommendations, and the new experimental treatments in metastatic HER2-positive breast cancer.
Abstract: The median survival of patients with HER2-positive metastatic breast cancer has more than doubled since the discovery of HER2-targeted treatments: it rose from less than 2 years in 2001 (prior introduction of trastuzumab) to more than 4 years in 2017. The initial generation of HER2-targeted therapies included trastuzumab with taxanes in the 1st line, followed by the addition of lapatinib and by a switch to another cytotoxic agent after progression. Results of CLEOPATRA, EMILIA and TH3RESA trials have changed this clinical practice. The current consensus includes horizontal dual blockade (trastuzumab+pertuzumab) with taxanes or vinorelbine in the 1st line, followed by trastuzumab-emtansine (T-DM1) in the 2nd line, with addition of lapatinib in the later lines of treatment. However, the fast and simultaneous development of new drugs led to a relative shortage of clinical evidence to support this sequence. Triple-positive breast cancers (TPBC), which express both hormonal receptors and HER2, constitute nearly half of HER2-positive cases. For these tumours, the current consensus is to add endocrine therapy after completion of cytotoxic treatment. Again, this consensus is not fully evidence-based. In view of the recent progress in treatment of oestrogen-receptor-positive breast cancers, a series of trials is evaluating addition of CDK4/6 inhibitors, aromatase inhibitors or fulvestrant to HER2-targeted and cytotoxic chemotherapy in TPBC patients. Despite the remarkable progress in treatment of HER2-positive breast cancer, metastatic disease is still incurable in the majority of patients. A wide range of novel therapies are under development to prevent and overcome resistance to current HER2-targeted agents. This review discusses pivotal clinical trials that have shaped current clinical practices, the current consensus recommendations and the new experimental treatments in metastatic HER2-positive breast cancer.
63 citations
TL;DR: The role of currently available or investigational HER2 tyrosine kinase inhibitors: lapatinib, neratinIB, afatinib and tucatinib in the treatment of brain metastases in HER2-positive breast cancer patients is reviewed.
TL;DR: Poziotinib showed the most potent activity against HER2 exon 20 mutations, and the secondary C805S at the covalent binding site of HER2 to poziot inib was identified as a potential mechanism of acquired resistance.
TL;DR: In this paper, the authors presented a computational analysis of resistance (CARE), a method focused on targeted therapies, to infer genome-wide transcriptomic signatures of drug efficacy from cell line compound screens, which can predict the therapy outcome better than signatures from other computational methods and genomics experiments.
Abstract: Summary Identifying reliable drug response biomarkers is a significant challenge in cancer research We present computational analysis of resistance (CARE), a computational method focused on targeted therapies, to infer genome-wide transcriptomic signatures of drug efficacy from cell line compound screens CARE outputs genome-scale scores to measure how the drug target gene interacts with other genes to affect the inhibitor efficacy in the compound screens Such statistical interactions between drug targets and other genes were not considered in previous studies but are critical in identifying predictive biomarkers When evaluated using transcriptome data from clinical studies, CARE can predict the therapy outcome better than signatures from other computational methods and genomics experiments Moreover, the CARE signatures for the PLX4720 BRAF inhibitor are associated with an anti-programmed death 1 clinical response, suggesting a common efficacy signature between a targeted therapy and immunotherapy When searching for genes related to lapatinib resistance, CARE identified PRKD3 as the top candidate PRKD3 inhibition, by both small interfering RNA and compounds, significantly sensitized breast cancer cells to lapatinib Thus, CARE should enable large-scale inference of response biomarkers and drug combinations for targeted therapies using compound screen data
TL;DR: Phosphorylation of PKM2-Y105 by activated kinases exerts oncogenic functions in part via activation of YAP downstream signaling to increase cancer stem-like cell properties.
Abstract: The role of pyruvate kinase M2 isoform (PKM2) in tumor progression has been controversial. Previous studies showed that PKM2 promoted tumor growth in xenograft models; however, depletion of PKM2 in the Brca1-loss-driven mammary tumor mouse model accelerates tumor formation. Since oncogenic kinases are frequently activated in tumors and PKM2 phosphorylation promotes tumor growth, we hypothesized that phosphorylation of PKM2 by activated kinases in tumor cells confers PKM2 oncogenic function, whereas non-phosphorylated PKM2 is non-oncogenic. Indeed, PKM2 was phosphorylated at tyrosine 105 (Y105) and formed oncogenic dimers in MDA-MB-231 breast cancer cells, whereas PKM2 was largely unphosphorylated and formed non-tumorigenic tetramers in non-transformed MCF10A cells. PKM2 knockdown did not affect MCF10A cell growth but significantly decreased proliferation of MDA-MB-231 breast cancer cells with tyrosine kinase activation. Multiple kinases that are frequently activated in different cancer types were identified to phosphorylate PKM2-Y105 in our tyrosine kinase screening. Introduction of the PKM2-Y105D phospho-mimetic mutant into MCF10A cells induced colony formation and the CD44hi/CD24neg cancer stem-like cell population by increasing YAP protein nuclear localization. ErbB2, a strong inducer of PKM2-Y105 phosphorylation, boosted nuclear localization of YAP and enhanced the cancer stem-like cell population. Treatment with the ErbB2 kinase inhibitor lapatinib decreased PKM2-Y105 phosphorylation and cancer stem-like cells, impeding PKM2 tumor-promoting function. Taken together, phosphorylation of PKM2-Y105 by activated kinases exerts oncogenic functions in part via activation of YAP downstream signaling to increase cancer stem-like cell properties.
TL;DR: It is suggested that HA coated LPT-NCs formulation enhances the activity of LPT against triple negative breast cancer, exhibiting magnificent therapeutic outcome at low dose thus presenting a strategy to reduce dose administrations and minimize dose related toxicity.
TL;DR: It is shown that lapatinib, an ATP-competitive inhibitor of HER2, is able to induce proliferation cooperatively with the HER3 ligand neuregulin, and this provides mechanistic insights into the liabilities involved in targeting kinases with ATP- competitive inhibitors.
Abstract: Around 20% of breast cancers are caused because cells have too many copies of a receptor protein called HER2 on their surface. HER2 is responsible for telling the cell to divide. Cells with too many of these receptors – and breast cancer cells can have up to 1000 times too many – divide uncontrollably. This causes the cancer to grow. Several successful anti-cancer drugs, such as Herceptin and Kadcyla, are used in the clinic to block the signals produced by HER2. Other drugs called kinase inhibitors prevent HER2 from building its faulty signals. However, a particular kinase inhibitor called lapatinib was not as successful in clinical trials as the medical community had hoped. Kinase inhibitors can have unexpected effects. While they can block specific signals in a cell, they can sometimes also cause new types of signals. Could this be one of the reasons behind the disappointing clinical trial results for lapatinib? By performing experiments on breast cancer cells grown in the laboratory, Claus, Patel et al. found that lapatinib can counterintuitively boost the growth of breast cancer cells. This occurs because lapatinib causes HER2 receptors to cluster together like a daisy chain along with another protein receptor of the same family, called HER3. These chains are primed to rapidly respond to a molecule called neuregulin, a growth factor that is commonly associated with breast cancer. The results presented by Claus, Patel et al. indicate that a particular subset of breast cancer patients – those whose cancer cells do not increase production of HER3 receptors – might better respond to lapatinib than others. The insights gained into what happens to HER2 when you try to block it should also influence the design of new drugs that target either HER2 or HER3.
TL;DR: Integrative analyses showed that models containing gene signatures, clinical features, and DNA information were better pCR predictors than models containing a single data type, as well as integrated RNA and DNA models.
Abstract: Purpose: Response to a complex trastuzumab-based regimen is affected by multiple features of the tumor and its microenvironment Developing a predictive algorithm is key to optimizing HER2-targeting therapyExperimental Design: We analyzed 137 pretreatment tumors with mRNA-seq and DNA exome sequencing from CALGB 40601, a neoadjuvant phase III trial of paclitaxel plus trastuzumab with or without lapatinib in stage II to III HER2-positive breast cancer We adopted an Elastic Net regularized regression approach that controls for covarying features within high-dimensional data First, we applied 517 known gene expression signatures to develop an Elastic Net model to predict pCR, which we validated on 143 samples from four independent trials Next, we performed integrative analyses incorporating clinicopathologic information with somatic mutation status, DNA copy number alterations (CNA), and gene signaturesResults: The Elastic Net model using only gene signatures predicted pCR in the validation sets (AUC = 076) Integrative analyses showed that models containing gene signatures, clinical features, and DNA information were better pCR predictors than models containing a single data type Frequently selected variables from the multiplatform models included amplifications of chromosome 6p, TP53 mutation, HER2-enriched subtype, and immune signatures Variables predicting resistance included Luminal/ER+ featuresConclusions: Models using RNA only, as well as integrated RNA and DNA models, can predict pCR with improved accuracy over clinical variables Somatic DNA alterations (mutation, CNAs), tumor molecular subtype (HER2E, Luminal), and the microenvironment (immune cells) were independent predictors of response to trastuzumab and paclitaxel-based regimens This highlights the complexity of predicting response in HER2-positive breast cancer Clin Cancer Res; 24(21); 5292-304 ©2018 AACR
TL;DR: Results indicate that coincident HER2 mutation reduces the efficacy of therapies commonly used to treat HER2-positive breast cancer, particularly in metastatic and previously HER2 inhibitor–treated patients, as well as potentially in patients scheduled for first-line treatment.
Abstract: Mutations in ERBB2, the gene encoding epidermal growth factor receptor (EGFR) family member HER2, are common in and drive the growth of "HER2-negative" (not ERBB2 amplified) tumors but are rare in "HER2-positive" (ERBB2 amplified) breast cancer. We analyzed DNA-sequencing data from HER2-positive patients and used cell lines and a patient-derived xenograft model to test the consequence of HER2 mutations on the efficacy of anti-HER2 agents such as trastuzumab, lapatinib, and neratinib, an irreversible pan-EGFR inhibitor. HER2 mutations were present in ~7% of HER2-positive tumors, all of which were metastatic but not all were previously treated. Compared to HER2 amplification alone, in both patients and cultured cell lines, the co-occurrence of HER2 mutation and amplification was associated with poor response to trastuzumab and lapatinib, the standard-of-care anti-HER2 agents. In mice, xenografts established from a patient whose HER2-positive tumor acquired a D769Y mutation in HER2 after progression on trastuzumab-based therapy were resistant to trastuzumab or lapatinib but were sensitive to neratinib. Clinical data revealed that six heavily pretreated patients with tumors bearing coincident HER2 amplification and mutation subsequently exhibited a statistically significant response to neratinib monotherapy. Thus, these findings indicate that coincident HER2 mutation reduces the efficacy of therapies commonly used to treat HER2-positive breast cancer, particularly in metastatic and previously HER2 inhibitor-treated patients, as well as potentially in patients scheduled for first-line treatment. Therefore, we propose that clinical studies testing the efficacy of neratinib are warranted selectively in breast cancer patients whose tumors carry both amplification and mutation of ERBB2/HER2.
Université libre de Bruxelles1, University of Texas MD Anderson Cancer Center2, Breast International Group3, Memorial Sloan Kettering Cancer Center4, The Breast Cancer Research Foundation5, University of Ulm6, Novartis7, University of Belgrade8, Ludwig Maximilian University of Munich9, Samsung Medical Center10, Mayo Clinic11, University of Bern12
TL;DR: The results suggest that TnT and proBNP may not be useful as early predictors of cardiac toxicity in anthracycline-naïve patients receiving trastuzumab and/or lapatinib.
Abstract: Biomarkers of cardiac damages, such as troponin T (TnT) and the amino-terminal fragment of brain natriuretic peptide (NT-proBNP), may be useful as early predictors of cardiac dysfunction. The role of these biomarkers in patients receiving lapatinib and/or trastuzumab before anthracyclines is unknown. This study explores TnT and NT-proBNP as predictors of early cardiac toxicity in neoadjuvant breast cancer patients. This sub-study of the NEOALTTO trial tested if changes in the levels of TnT and NT-proBNP occurred after 2 weeks of anti-HER2 therapy (lapatinib, trastuzumab or their combination) alone and/or after 18 weeks of anti-HER2 therapy plus weekly paclitaxel. 173 and 172 were tested at all three timepoints for NT-proBNP and TnT, respectively. The incidence of biomarker elevation was overall low at all timepoints for all the three treatment arms. A total of 13 CEs in 11 patients occurred. Biomarker elevations in patients with CEs were very rare; only one patient with subsequent CE had a NT-proBNP elevation at baseline and at week 2. These results suggest that TnT and proBNP may not be useful as early predictors of cardiac toxicity in anthracycline-naive patients receiving trastuzumab and/or lapatinib.
TL;DR: There is ongoing work to optimize and de‐escalate treatment in patients who may do just as well with less therapy and can avoid unnecessary treatments and their related toxicities.
Abstract: Significant advances have occurred in the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer that have changed its natural history. The addition of trastuzumab to standard therapy has dramatically improved the prognosis for patients with early stage, HER2-positive breast cancer to unprecedented survival outcomes. Yet, long-term follow-up data from adjuvant pivotal trials indicate that 15-24% of patients still develop recurrent disease. Most of the research has focused on the addition of novel anti-HER2 drugs to standard therapy, including studies evaluating the monoclonal antibody pertuzumab; the antibody-drug conjugate trastuzumab-emtansine (T-DM1); the selective, reversible HER2/epidermal growth factor receptor kinase inhibitor lapatinib; or the irreversible pan-HER2 inhibitor neratinib. Dual HER2 blockade has improved overall survival remarkably in metastatic breast cancer; however, in patients with early stage disease, it has led to small benefits in progression-free survival. Moreover, biologic heterogeneity within HER2-positive disease may determine response to treatment and prognosis. Different subgroups of patients with HER2-positive breast cancer may benefit from different therapeutic approaches. Thus, there is ongoing work to optimize and de-escalate treatment in patients who may do just as well with less therapy and can avoid unnecessary treatments and their related toxicities. The objective of this review is to summarize the background and latest evidence on the current management of early stage, HER2-positive breast cancer and to present novel perspectives on its management.
TL;DR: This work shows that oncogenic HER2 tyrosine kinase signaling induces phosphorylation of mitochondrial creatine kinase 1 (MtCK1) in an ABL-dependent manner in breast cancer cells, and suggests that activation of the phosphocreatine energy shuttle by MtCK 1 Y153 phosphorylated creates a druggable metabolic vulnerability in cancer.
TL;DR: The engineering of a nanomedicine to effectively inhibit the growth regulatory kinase mTORC2 in a preclinical model of breast cancer, targeting an important pathogenic enzyme in that setting that has been undruggable to date is described.
Abstract: Small molecule inhibitors of the mTORC2 kinase (torkinibs) have shown efficacy in early clinical trials. However, the torkinibs under study also inhibit the other mTOR-containing complex mTORC1. While mTORC1/mTORC2 combined inhibition may be beneficial in cancer cells, recent reports describe compensatory cell survival upon mTORC1 inhibition due to loss of negative feedback on PI3K, increased autophagy, and increased macropinocytosis. Genetic models suggest that selective mTORC2 inhibition would be effective in breast cancers, but the lack of selective small molecule inhibitors of mTORC2 have precluded testing of this hypothesis to date. Here we report the engineering of a nanoparticle-based RNAi therapeutic that can effectively silence the mTORC2 obligate cofactor Rictor. Nanoparticle-based Rictor ablation in HER2-amplified breast tumors was achieved following intra-tumoral and intra-venous delivery, decreasing Akt phosphorylation and increasing tumor cell killing. Selective mTORC2 inhibition in vivo, combined with the HER2 inhibitor lapatinib, decreased the growth of HER2-amplified breast cancers to a greater extent than either agent alone, suggesting that mTORC2 promotes lapatinib resistance but is overcome by mTORC2 inhibition. Importantly, selective mTORC2 inhibition was effective in a TNBC model, decreasing Akt phosphorylation and tumor growth, consistent with our findings that RICTOR mRNA correlates with worse outcome in patients with basal-like TNBC. Together, our results offer preclinical validation of a novel RNAi delivery platform for therapeutic gene ablation in breast cancer, and they show that mTORC2-selective targeting is feasible and efficacious in this disease setting.
TL;DR: The present study presents a promising candidate for further design and development of novel EGFR/HER2 inhibitors capable of overcoming EGFR TKIs resistance, 27b, which dramatically reduced the viability of various patient-derived cancer cells preferentially overexpressing EGFR/.
TL;DR: These results show that prostate cancer cells are primed to undergo apoptosis and that cotargeting BCLXL and MCL1, directly or indirectly through agents that increase M CL1 degradation, can induce dramatic apoptotic responses.
Abstract: Purpose: Clinically available BH3 mimetic drugs targeting BCLXL and/or BCL2 (navitoclax and venetoclax, respectively) are effective in some hematologic malignancies, but have limited efficacy in solid tumors. This study aimed to identify combination therapies that exploit clinical BH3 mimetics for prostate cancer. Experimental Design: Prostate cancer cells or xenografts were treated with BH3 mimetics as single agents or in combination with other agents, and effects on MCL1 and apoptosis were assessed. MCL1 was also targeted directly using RNAi, CRISPR, or an MCL1-specific BH3 mimetic, S63845. Results: We initially found that MCL1 depletion or inhibition markedly sensitized prostate cancer cells to apoptosis mediated by navitoclax, but not venetoclax, in vitro and in vivo, indicating that they are primed to undergo apoptosis and protected by MCL1 and BCLXL. Small-molecule EGFR kinase inhibitors (erlotinib, lapatinib) also dramatically sensitized to navitoclax-mediated apoptosis, and this was associated with markedly increased proteasome-dependent degradation of MCL1. This increased MCL1 degradation appeared to be through a novel mechanism, as it was not dependent upon GSK3β-mediated phosphorylation and subsequent ubiquitylation by the ubiquitin ligases βTRCP and FBW7, or through other previously identified MCL1 ubiquitin ligases or deubiquitinases. Inhibitors targeting additional kinases (cabozantinib and sorafenib) similarly caused GSK3β-independent MCL1 degradation, and in combination with navitoclax drove apoptosis in vitro and in vivo. Conclusions: These results show that prostate cancer cells are primed to undergo apoptosis and that cotargeting BCLXL and MCL1, directly or indirectly through agents that increase MCL1 degradation, can induce dramatic apoptotic responses. Clin Cancer Res; 24(21); 5458–70. ©2018 AACR.
TL;DR: Poziotinib showed meaningful activity in these heavily treated HER2‐positive mBCs and biomarker studies analyzed are warranted to support further evaluation of this treatment in such cases.
Abstract: Although the introduction of human epidermal growth factor receptor (HER)2-directed therapy including trastuzumab, pertuzumab, lapatinib and trastuzumab emtansine (T-DM1) in the treatment of HER2-positive metastatic breast cancers (mBCs) favorably changed the natural history of this disease, most cases of HER2-positive mBC will eventually progress Poziotinib is an oral pan-HER kinase inhibitor showing potent activity through irreversible inhibition of these kinases This open-label, multicenter phase II study was designed to evaluate the efficacy and safety of poziotinib monotherapy in patients with HER2-positive mBC who had progressed from more than two HER2-directed therapies Patients received 12 mg poziotinib once daily on a 14-day on/7-day off schedule Progression-free survival (PFS) as the primary endpoint, the objective response rate (ORR), overall survival (OS) and safety were evaluated From April 2015 to February 2016, 106 patients were enrolled in the trial from seven institutes in South Korea They had a median age of 51 years (range 30-76) and had received a median of four prior therapies including two HER2-directed therapies for advanced or metastatic cancers The median follow-up duration was 12 months The median PFS was 404 months (95% confidence interval [CI], 294-440 months), and median overall survival has not been reached The most common treatment-related adverse events were (total/grade ≥3) diarrhea (9623%/1415%), stomatitis (9245%/1226%) and rashes (6321%/377%) Poziotinib showed meaningful activity in these heavily treated HER2-positive mBCs Diarrhea and stomatitis were the major toxicities Biomarker studies analyzed are warranted to support further evaluation of this treatment in such cases
TL;DR: A computational approach is developed to model the in vitro cellular dynamics of the EGFR-mutant cell line SF268 in response to different lapatinib concentrations and dosing schedules and predicts that continuous dosing remains the best clinically feasible strategy for slowing down tumor growth and lowering overall tumor burden.
Abstract: Human primary glioblastomas (GBM) often harbor mutations within the epidermal growth factor receptor (EGFR). Treatment of EGFR-mutant GBM cell lines with the EGFR/HER2 tyrosine kinase inhibitor lapatinib can effectively induce cell death in these models. However, EGFR inhibitors have shown little efficacy in the clinic, partly because of inappropriate dosing. Here, we developed a computational approach to model the in vitro cellular dynamics of the EGFR-mutant cell line SF268 in response to different lapatinib concentrations and dosing schedules. We then used this approach to identify an effective treatment strategy within the clinical toxicity limits of lapatinib, and developed a partial differential equation modeling approach to study the in vivo GBM treatment response by taking into account the heterogeneous and diffusive nature of the disease. Despite the inability of lapatinib to induce tumor regressions with a continuous daily schedule, our modeling approach consistently predicts that continuous dosing remains the best clinically feasible strategy for slowing down tumor growth and lowering overall tumor burden, compared to pulsatile schedules currently known to be tolerated, even when considering drug resistance, reduced lapatinib tumor concentrations due to the blood brain barrier, and the phenotypic switch from proliferative to migratory cell phenotypes that occurs in hypoxic microenvironments. Our mathematical modeling and statistical analysis platform provides a rational method for comparing treatment schedules in search for optimal dosing strategies for glioblastoma and other cancer types.
TL;DR: The findings suggest that iNOS inhibition is a promising cardioprotective strategy to accompany HER2-inhibitor/anthracycline combination therapies and support the promise of hPSC-CMs as a platform for investigating cardiotoxicity and developing cardiopRotectants as a whole.
Abstract: Rationale: Lapatinib (LAP) is a crucial alternative to trastuzumab upon the onset of drug resistance during treatment of metastatic human epidermal growth factor receptor 2-positive breast cancer. Like trastuzumab, LAP is commonly used alongside anthracyclines as a combination therapy, due to enhanced anti-cancer efficacy. However, this is notably associated with cardiotoxicity so it is imperative to understand the mechanisms driving this cardiotoxicity and develop cardioprotective strategies. To this end, here we utilize human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs), which exhibit several characteristics representative of in vivo cardiomyocytes that make them breakthrough models to study drug toxicity. Methods: We investigated LAP- and doxorubicin (DOX)-induced toxicity in hPSC-CMs and evaluated the involvement of inducible nitric oxide (NO) synthase (iNOS). The significance of iNOS-mediated cardiotoxicity was furthermore evaluated in animal studies. Results: LAP synergistically increased DOX toxicity in hPSC-CMs in a dose- and time-dependent manner. At concentrations that were otherwise non-apoptotic when administered separately, LAP significantly potentiated DOX-induced hPSC-CM apoptosis. This was accompanied by increased iNOS expression and pronounced production of NO. iNOS inhibition significantly reduced hPSC-CM sensitivity to LAP and DOX co-treatment (LAP-plus-DOX), leading to reduced apoptosis. Consistent with our observations in vitro, delivery of an iNOS inhibitor in mice treated with LAP-plus-DOX attenuated myocardial apoptosis and systolic dysfunction. Moreover, inhibition of iNOS did not compromise the anti-cancer potency of LAP-plus-DOX in a murine breast cancer xenograft model. Conclusions: Our findings suggest that iNOS inhibition is a promising cardioprotective strategy to accompany HER2-inhibitor/anthracycline combination therapies. Furthermore, these results support the promise of hPSC-CMs as a platform for investigating cardiotoxicity and developing cardioprotectants as a whole.
TL;DR: In patients with hormone receptor-positive tumors, prolonged anti-HER2 treatment-neoadjuvant lapatinib for 6 months, followed by adjuvant trastuzumab for 12 months-significantly improved survival compared with anti- HER2 treatment with trastzumab alone.
Abstract: PurposeThe GeparQuinto phase III trial demonstrated a lower pathologic complete response (pCR; pT0 ypN0) rate when lapatinib was added to standard anthracycline–taxane chemotherapy compared with trastuzumab in patients with human epidermal growth factor receptor 2 (HER2) –positive breast cancer. Here, we report the long-term outcomes.MethodsPatients with HER2-positive tumors (n = 615) received neoadjuvant treatment with epirubicin (E) plus cyclophosphamide (C), followed by docetaxel (T) in combination with either lapatinib (L) or trastuzumab (H; ECH-TH arm: n = 307; ECL-TL arm: n = 308). All patients received adjuvant trastuzumab for a total of 12 months and 18 months in the ECH-TH and ECL-TL arms, respectively. Median follow-up was 55 months.ResultsThree-year disease-free survival (DFS), distant DFS (DDFS), and overall survival (OS) were not significantly different between the two treatment arms. Long-term outcomes correlated with pCR (DFS: hazard ratio [HR], 0.63; P = .042; DDFS: HR, 0.55; P = .021; and...
University of Erlangen-Nuremberg1, University of Tübingen2, University of Ulm3, Technische Universität München4, Charité5, Heidelberg University6, University of Hamburg7, Dresden University of Technology8, Ludwig Maximilian University of Munich9, Martin Luther University of Halle-Wittenberg10, University of Düsseldorf11
TL;DR: High Eastern Cooperative Oncology Group (ECOG) scores, negative hormone receptor status, and visceral or brain metastases were associated with more frequent use of this therapy sequence, and most patients received T-DM1 after treatment with pertuzumab.
Abstract: This study presents comprehensive real-world data on the use of anti-human epidermal growth factor receptor 2 (HER2) therapies in patients with HER2-positive metastatic breast cancer (MBC). Specifically, it describes therapy patterns with trastuzumab (H), pertuzumab + trastuzumab (PH), lapatinib (L), and trastuzumab emtansine (T-DM1). The PRAEGNANT study is a real-time, real-world registry for MBC patients. All therapy lines are documented. This analysis describes the utilization of anti-HER2 therapies as well as therapy sequences. Among 1936 patients in PRAEGNANT, 451 were HER2-positive (23.3%). In the analysis set (417 patients), 53% of whom were included in PRAEGNANT in the first-line setting, 241 were treated with H, 237 with PH, 85 with L, and 125 with T-DM1 during the course of their therapies. The sequence PH → T-DM1 was administered in 51 patients. Higher Eastern Cooperative Oncology Group (ECOG) scores, negative hormone receptor status, and visceral or brain metastases were associated with more frequent use of this therapy sequence. Most patients received T-DM1 after treatment with pertuzumab. Both novel therapies (PH and T-DM1) are utilized in a high proportion of HER2-positive breast cancer patients. As most patients receive T-DM1 after PH, real-world data may help to clarify whether the efficacy of this sequence is similar to that in the approval study.
TL;DR: It is shown that BRAF inhibition leads to the upregulation of a variety of receptor tyrosine kinases (RTKs) in CRC cell lines, including not only the EGFR, but also human epidermal growth factor receptor (HER) 2 and HER3, which indicates that a broad suppression of RTK signaling might be beneficial and should be taken into account in future research addressing targeted therapy in BRAF-mutant CRC.
Abstract: BRAF mutations occur in ~10% of colorectal cancer (CRC) and are associated with poor prognosis. Inhibitors selective for the BRAFV600E oncoprotein, the most common BRAF mutant, elicit only poor response rates in BRAF-mutant CRC as single agents. This unresponsiveness was mechanistically attributed to the loss of negative feedbacks on the epidermal growth factor receptor (EGFR) and initiated clinical trials that combine BRAF (and MEK) inhibitors, either singly or in combination, with the anti-EGFR antibodies cetuximab or panitumumab. First results of these combinatorial studies demonstrated improved efficacy, however, the response rates still were heterogeneous. Here, we show that BRAF inhibition leads to the upregulation of a variety of receptor tyrosine kinases (RTKs) in CRC cell lines, including not only the EGFR, but also human epidermal growth factor receptor (HER) 2 and HER3. Importantly, combination of the BRAF inhibitors (BRAFi) vemurafenib (PLX4032), dabrafenib, or encorafenib with inhibitors dually targeting the EGFR and HER2 (such as lapatinib, canertinib, and afatinib) significantly reduced the metabolic activity and proliferative potential of CRC cells. This re-sensitization was also observed after genetic depletion of HER2 or HER3. Interestingly, BRAF inhibitors did not only upregulate RTKs, but also increased the abundance of the GRB2-associated binders (Gab) 1 and Gab2, two important amplifiers of RTK signaling. An allele-specific shRNA-mediated knockdown of BRAFV600E revealed that Gab2 upregulation was directly dependent on the loss of the oncoprotein and was not caused by an “off-target” effect of these kinase inhibitors. Furthermore, Gab2 and Gab2-mediated Shp2 signaling were shown to be functionally important in BRAFi resistance. These findings highlight potential new escape mechanisms to these targeted therapies and indicate that a broad suppression of RTK signaling might be beneficial and should be taken into account in future research addressing targeted therapy in BRAF-mutant CRC.