Does lapatinib, a small-molecule tyrosine kinase inhibitor, constitute a breakthrough in the treatment of breast cancer?

INPP4B suppresses HER2-induced mesenchymal transition in HER2+ breast cancer and enhances sensitivity to Lapatinib

Human epidermal growth factor receptor 2 positive (HER2+) breast cancer (BC) tends to metastasize and has a bad prognosis due to its high malignancy and rapid progression. Inositol polyphosphate 4-phosphatase isoenzymes type II (INPP4B) plays unequal roles in the development of various cancers. However, the function of INPP4B in HER2+ BC has not been elucidated. Here we found that INPP4B expression was significantly lower in HER2+ BC and positively correlated with the prognosis by bioinformatics and tissue immunofluorescence analyses. Overexpression of INPP4B inhibited cell proliferation, migration, and growth of xenografts in HER2+ BC cells. Conversely, depletion of INPP4B reversed these effects and activated the PDK1/AKT and Wnt/β-catenin signaling pathways to promote epithelial-mesenchymal transition (EMT) progression. Moreover, INPP4B overexpression blocked epidermal growth factor (EGF) -induced cell proliferation, migration and EMT progression, whereas INPP4B depletion antagonized HER2 depletion in reduction of cell proliferation and migration of HER2+ BC cells. Additionally, Lapatinib (LAP) inhibited HER2+ BC cell survival, proliferation and migration, and its effect was further enhanced by overexpression of INPP4B. In summary, our results illustrate that INPP4B suppresses HER2+ BC growth, migration and EMT, and its expression level affects patient outcome, further providing new insights into clinical practice.

PIM kinase inhibitor AZD1208 in conjunction with Th1 cytokines potentiate death of breast cancer cellsin vitrowhile also maximizing suppression of tumor growthin vivo when combined with immunotherapy

PIM kinases are over-expressed by a number of solid malignancies including breast cancer, and are thought to regulate proliferation, survival, and resistance to treatment, making them attractive therapeutic targets. Because PIM kinases sit at the nexus of multiple oncodriver pathways, PIM antagonist drugs are being tested alone and in conjunction with other therapies to optimize outcomes. We therefore sought to test the combination of pharmacological PIM antagonism and Th1-associated immunotherapy. We show that the pan PIM antagonist, AZD1208, when combined in vitro with Th1 cytokines IFN-γ and TNF-α, potentiates metabolic suppression, overall cell death, and expression of apoptotic markers in human breast cancer cell lines of diverse phenotypes (HER-2pos/ERneg, HER-2pos/ERpos and triple-negative). Interestingly, AZD1208 was shown to moderately inhibit IFN-γ secretion by stimulated T lymphocytes of both human and murine origin, suggesting some inherent immunosuppressive activity of the drug. Nonetheless, when multiplexed therapies were tested in a murine model of HER-2pos breast cancer, combinations of HER-2 peptide-pulsed DCs and AZD1208, as well as recombinant IFN-γ plus AZD1208 significantly suppressed tumor outgrowth compared with single-treatment and control groups. These studies suggest that PIM antagonism may combine productively with certain immunotherapies to improve responsiveness.

Candidate biomarker assessment for pharmacological response

Using the information from our CellMiner (https://discover.nci.nih.gov/cellminer/) and CellMinerCDB (https://discover.nci.nih.gov/cellminercdb/) web-based applications, we identified 3978 molecular events with significant links to pharmacological response for genes that are either targets, biomarkers, or have established causal linkage to drugs. Molecular events included DNA copy number, methylation and mutation; and transcript; and whole or phospho-protein expression for the NCI-60 human cancer cell lines. While all forms of molecular data were informative in some (gene-drug) pairings, the type of significantly linked molecular events was found to vary widely by drug. Some forms of molecular data were found to have more frequent significant correlation than others. Leading were phosphoproteins as measured by antibody (31%), followed by transcript as measured by microarray (16%), and total protein levels as measured by mass spectrometry or antibody (14%). All other measurements ranged between 5 and 11%. Data reliability was underscored by concordant results when using differing drugs with the same targets, as well as different measurements of the same molecular parameter. The significance of correlations of the various molecular parameters to the pharmacological responses provides functional indication of those parameters that are biologically relevant for each gene-drug pairing, as well as comparisons between measurement types.

Autophagy as a pharmacological target in hematopoiesis and hematological disorders

Autophagy is involved in many cellular processes, including cell homeostasis, cell death/survival balance and differentiation. Autophagy is essential for hematopoietic stem cell survival, quiescence, activation and differentiation. The deregulation of this process is associated with numerous hematological disorders and pathologies, including cancers. Thus, the use of autophagy modulators to induce or inhibit autophagy emerges as a potential therapeutic approach for treating these diseases and could be particularly interesting for differentiation therapy of leukemia cells. This review presents therapeutic strategies and pharmacological agents in the context of hematological disorders. The pros and cons of autophagy modulators in therapy will also be discussed.

Lapatinib Inhibits Breast Cancer Cell Proliferation by Influencing PKM2 Expression

Pyruvate kinase type M2, which is expressed in multiple tumor cell types and plays a key role in aerobic glycolysis, also has nonglycolytic functions and can regulate transcription and cell proliferation. The results of this study show that epidermal growth factor receptor activation induces pyruvate kinase type M2 nuclear translocation. To further determine the relationship between pyruvate kinase type M2 and epidermal growth factor receptor, we analyzed pathological data from mammary glands and performed epidermal growth factor receptor/human epidermal growth factor receptor 2 knockdown to reveal that pyruvate kinase type M2 is associated with epidermal growth factor receptor and human epidermal growth factor receptor 2. Lapatinib is a small molecule epidermal growth factor receptor tyrosine kinase inhibitor that can inhibit epidermal growth factor receptor and human epidermal growth factor receptor 2, though its effect on pyruvate kinase type M2 remains elusive. Accordingly, we performed Western blotting and reverse transcription polymerase chain reaction and analyzed pathological data from mammary glands, with results suggesting that lapatinib inhibits pyruvate kinase type M2 expression. We further found that the antitumor drug lapatinib inhibits breast cancer cell proliferation by influencing pyruvate kinase type M2 expression, as based on Cell Counting Kit-8 analyses and pyruvate kinase type M2 overexpression experiments. Signal transducer and activator of transcription 3, which is a transcription factor-associated cell proliferation and the only transcription factor that interacts with pyruvate kinase type M2, we performed pyruvate kinase type M2 knockdown experiments in Human breast cancer cells MDA-MB-231 and Human breast cancer cells SK-BR-3 cell lines and examined the effect on levels of Signal transducer and activator of transcription 3 and phosphorylated Signal transducer and activator of transcription 3. The results indicate that pyruvate kinase type M2 regulates Signal transducer and activator of transcription 3 and phospho-Stat3 (Tyr705) expression. Together with previous reports, our findings show that lapatinib inhibits breast cancer cell proliferation by influencing pyruvate kinase type M2 expression, which results in a reduction in both Signal transducer and activator of transcription 3 and phosphorylated Signal transducer and activator of transcription 3.

Effects of lapatinib on cell proliferation and apoptosis in NB4 cells

Acute promyelocytic leukemia (APL), characterized by the presence of the promyelocytic leukemia (PML)-retinoic acid α receptor (RARα) fusion protein, responds to treatment with all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). However, drug resistance and side effects restrict the application of these reagents. Hence, the development of novel therapeutic drugs for APL treatment is critical. Lapatinib, a small-molecule tyrosine kinase inhibitor, has been used in the treatment of different tumors. However, it is unclear whether lapatinib exerts antitumor effects on APL. The present study investigated the antitumor effects and potential mechanisms of lapatinib on NB4 cells derived from APL. Cell Counting Kit-8 assay and colony forming analysis indicated that lapatinib inhibited NB4 cell proliferation in a dose-dependent manner. Flow cytometry analysis revealed that lapatinib induced cell cycle arrest at the S phase and promoted cell apoptosis. Furthermore, Liu's staining and Hoechst 33258 staining revelaed that lapatinib treatment induced an apoptotic nuclear phenomenon. Furthermore, lapatinib induced apoptosis by decreasing Bcl-2 and PML-RARα levels, and by increasing the levels of Bax, cleaved PARP, cleaved caspase-3 and cleaved caspase-9. In addition, lapatinib increased the levels of phospho-p38 MAPK and phospho-JNK, and decreased the levels of phospho-Akt. The p38 inhibitor PD169316 partially blocked lapatinib-induced proliferation inhibition and apoptosis, whereas the JNK inhibitor SP600125 had no such effects. Therefore, treatment with lapatinib may be a promising strategy for APL therapy.

Targeted therapies in breast cancer: New challenges to fight against resistance

Breast cancer is the most common type of cancer found in women and today represents a significant challenge to public health. With the latest breakthroughs in molecular biology and immunotherapy, very specific targeted therapies have been tailored to the specific pathophysiology of different types of breast cancers. These recent developments have contributed to a more efficient and specific treatment protocol in breast cancer patients. However, the main challenge to be further investigated still remains the emergence of therapeutic resistance mechanisms, which develop soon after the onset of therapy and need urgent attention and further elucidation. What are the recent emerging molecular resistance mechanisms in breast cancer targeted therapy and what are the best strategies to apply in order to circumvent this important obstacle? The main scope of this review is to provide a thorough update of recent developments in the field and discuss future prospects for preventing resistance mechanisms in the quest to increase overall survival of patients suffering from the disease.

EGFR Family Members' Regulation of Autophagy Is at a Crossroads of Cell Survival and Death in Cancer

The epidermal growth factor receptor (EGFR) signaling pathways are altered in many cancers contributing to increased cell survival. These alterations are caused mainly through increased expression or mutation of EGFR family members EGFR, ErbB2, ErbB3, and ErbB4. These receptors have been successfully targeted for cancer therapy. Specifically, a monoclonal antibody against ErbB2, trastuzumab, and a tyrosine kinase inhibitor against EGFR, gefitinib, have improved the survival of breast and lung cancer patients. Unfortunately, cancer patients frequently become resistant to these inhibitors. This has led to investigating how EGFR can contribute to cell survival and how cancer cells can overcome inhibition of its signaling. Indeed, it is coming into focus that EGFR signaling goes beyond a single signal triggering cell proliferation and survival and is a sensor that regulates the cell’s response to microenvironmental stresses such as hypoxia. It acts as a switch that modulates the ability of cancer cells to survive. Autophagy is a process of self-digestion that is inhibited by EGFR allowing cancer cells to survive under stresses that would normally cause death and become resistant to chemotherapy. Inhibiting EGFR signaling allows autophagy to contribute to cell death. This gives new opportunities to develop novel therapeutic strategies to treat cancers that rely on EGFR signaling networks and autophagy. In this review, we summarize the current understanding of EGFR family member regulation of autophagy in cancer cells and how new therapeutic strategies could be developed to overcome drug resistance.

Lapatinib induces autophagic cell death and differentiation in acute myeloblastic leukemia

Lapatinib is an oral-form dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR or ErbB/Her) superfamily members with anticancer activity. In this study, we examined the effects and mechanism of action of lapatinib on several human leukemia cells lines, including acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and acute lymphoblastic leukemia (ALL) cells. We found that lapatinib inhibited the growth of human AML U937, HL-60, NB4, CML KU812, MEG-01, and ALL Jurkat T cells. Among these leukemia cell lines, lapatinib induced apoptosis in HL-60, NB4, and Jurkat cells, but induced nonapoptotic cell death in U937, K562, and MEG-01 cells. Moreover, lapatinib treatment caused autophagic cell death as shown by positive acridine orange staining, the massive formation of vacuoles as seen by electronic microscopy, and the upregulation of LC3-II, ATG5, and ATG7 in AML U937 cells. Furthermore, autophagy inhibitor 3-methyladenine and knockdown of ATG5, ATG7, and Beclin-1 using short hairpin RNA (shRNA) partially rescued lapatinib-induced cell death. In addition, the induction of phagocytosis and ROS production as well as the upregulation of surface markers CD14 and CD68 was detected in lapatinib-treated U937 cells, suggesting the induction of macrophagic differentiation in AML U937 cells by lapatinib. We also noted the synergistic effects of the use of lapatinib and cytotoxic drugs in U937 leukemia cells. These results indicate that lapatinib may have potential for development as a novel antileukemia agent.

Lapatinib induces autophagy, apoptosis and megakaryocytic differentiation in chronic myelogenous leukemia K562 cells

Lapatinib is an oral, small-molecule, dual tyrosine kinase inhibitor of epidermal growth factor receptors (EGFR, or ErbB/Her) in solid tumors. Little is known about the effect of lapatinib on leukemia. Using human chronic myelogenous leukemia (CML) K562 cells as an experimental model, we found that lapatinib simultaneously induced morphological changes resembling apoptosis, autophagy, and megakaryocytic differentiation. Lapatinib-induced apoptosis was accompanied by a decrease in mitochondrial transmembrane potential and was attenuated by the pancaspase inhibitor z-VAD-fmk, indicating a mitochondria-mediated and caspase-dependent pathway. Lapatinib-induced autophagic cell death was verified by LC3-II conversion, and upregulation of Beclin-1. Further, autophagy inhibitor 3-methyladenine as well as autophagy-related proteins Beclin-1 (ATG6), ATG7, and ATG5 shRNA knockdown rescued the cells from lapatinib-induced growth inhibition. A moderate number of lapatinib-treated K562 cells exhibited features of megakaryocytic differentiation. In summary, lapatinib inhibited viability and induced multiple cellular events including apoptosis, autophagic cell death, and megakaryocytic differentiation in human CML K562 cells. This distinct activity of lapatinib against CML cells suggests potential for lapatinib as a therapeutic agent for treatment of CML. Further validation of lapatinib activity in vivo is warranted.

Targeting the tumor microenvironment: focus on angiogenesis

Tumorigenesis is a complex multistep process involving not only genetic and epigenetic changes in the tumor cell but also selective supportive conditions of the deregulated tumor microenvironment. One key compartment of the microenvironment is the vascular niche. The role of angiogenesis in solid tumors but also in hematologic malignancies is now well established. Research on angiogenesis in general, and vascular endothelial growth factor in particular, is a major focus in biomedicine and has led to the clinical approval of several antiangiogenic agents including thalidomide, bevacizumab, sorafenib, sunitinib, pazopanib, temesirolimus, and everolimus. Indeed, antiangiogenic agents have significantly changed treatment strategies in solid tumors (colorectal cancer, renal cell carcinoma, and breast cancer) and multiple myeloma. Here we illustrate important aspects in the interrelationship between tumor cells and the microenvironment leading to tumor progression, with focus on angiogenesis, and summarize derived targeted therapies.

Eradication of breast cancer cells in patients with distant metastasis: the finishing touches?

Cytotoxic agents are significantly active in breast cancer cells, but their usefulness has been limited in treating metastatic breast cancer (MBC). This has facilitated the development of an approach using molecular-targeted agents. Intrinsic subtypes including luminal A, luminal B, human epidermal growth factor receptor type 2 (HER2)-enriched, basal-like, and claudin-low tumors exhibit original drug responsiveness and clinical prognosis. Anti-HER2 treatments, trastuzumab or lapatinib, have demonstrated clinically significant efficacy. Poly ADP-ribose polymerase-1 inhibitors act against BRCA1-disabled breast cancer. Cancer stem cells could be the major obstacle to achieving a cure in systemic treatment. Extensive investigations are underway to develop novel agents that act on the genes or signaling of Hedgehog, Wnt, and Notch, which regulate cancer stem cells. Cancer cells undergo epithelial-mesenchymal transition (EMT) and acquire invasive properties. Breast cancer cells alter their phenotype in blood and bone marrow, e.g., circulating tumor cells or disseminated tumor cells. Cancer stem cells, like normal stem cells, may exist at niches in bone marrow. To achieve a cure for MBC, it is necessary to disrupt cancer stem cell-niche interactions or eradicate cancer stem cells. Traditional treatments with cytotoxic or endocrine agents require development in relation to intrinsic subtypes, stem cells, or EMT.

Antiangiogenic strategies in breast cancer management

Angiogenesis is considered one of the key mechanisms of tumour growth and survival. Therefore it represents an ideal pharmaceutical target. Many antiangiogenic agents have been developed so far in several solid tumours and also in breast cancer. Vascular endothelial growth factor (VEFG) is the main target and both monoclonal antibodies and small molecules belonging to the tyrosine kinase inhibitors directed against VEGF(R) have been developed. Some other therapeutic approaches have shown to exert some antiangiogenic activity, such as hormonal agents, metronomic chemotherapy, bisphosphonates and others. In this paper we provide an introduction of the current data supporting the angiogenesis in breast cancer and a review of the most relevant antiagiogenic therapies which have been investigated so far.

Lapatinib: a review of its use in the treatment of HER2-overexpressing, trastuzumab-refractory, advanced or metastatic breast cancer

Lapatinib (Tyverb, Tykerb) is an orally active, small molecule, reversible, dual tyrosine kinase inhibitor of human epidermal growth factor receptor type 1 (HER1) and type 2 (HER2). In the EU, lapatinib in combination with capecitabine is indicated for the treatment of women with HER2-overexpressing, advanced or metastatic breast cancer that has progressed after treatment with regimens that include anthracyclines, taxanes and, in the metastatic setting, trastuzumab. The orally administered combination of lapatinib and capecitabine was a more effective treatment than capecitabine alone, and was a generally well tolerated, conveniently administered combination for women with trastuzumab-refractory, HER2-positive advanced or metastatic breast cancer in a clinical trial. Lapatinib combined with capecitabine provides an effective therapeutic option for a group of patients who currently have few treatment choices.

[Lapatinib treatment-option in trastuzumab-resistant breast cancer]

HER2 is overexpressed in 20-25% of breast cancers and is associated with an aggressive phenotype and poor prognosis. Lapatinib is a dual tyrosine kinase inhibitor selective for inhibition of epidermal growth factor receptor (EGFR1/ErbB1) and HER2/ErbB2. Having more targets, probably its antitumor activity could be more efficient. Preclinical data reveal that lapatinib has activity in trastuzumab-resistant cell lines as well as synergistic activity with trastuzumab. Phase I clinical trials have also shown that lapatinib is well tolerated, with mild diarrhea and skin rush as common toxic effects and low incidence of cardiotoxicity. Lapatinib can cross the blood-brain barrier and might therefore have a role in preventing central-nervous-system progression. In a pivotal phase III trial, a combination of lapatinib and capecitabine almost doubled time to disease progression when compared to capecitabine alone (8.4 vs. 4.1 months) in women with HER2/ErbB2-positive advanced or metastatic breast cancer previously treated with anthracyclin, taxanes and trastuzumab. The overall survival was 15.6 vs. 15.4 months. Several clinical trials that explore the efficacy of lapatinib in combination with conventional chemotherapeutic agents, hormone therapy and other target therapies are ongoing in advanced breast cancer or in neo-adjuvant and adjuvant settings.

Vasoactive intestinal peptide (VIP) induces transactivation of EGFR and HER2 in human breast cancer cells

We analyzed the cross-talk between receptors for vasoactive intestinal peptide (VIP) and the human epidermal growth factor family of tyrosine kinase receptors (HER) in oestrogen-dependent (T47D) and oestrogen-independent (MDA-MB-468) human breast cancer cells. VIP treatment slowly increased the expression levels of EGFR but it rapidly augmented phosphorylation of EGFR and HER2 in both cell lines. This pattern of HERs transactivation was blocked by the specific VIP antagonist JV-1-53, supporting the direct involvement of VIP receptors in formation of P-EGFR and P-HER2. VIP-induced transactivation was also abolished by H89 (protein kinase A inhibitor), PP2 (Src inhibitor) or TAPI-1 (inhibitor of matrix metalloproteases), following a differential pattern. These results shed a new light on the specific signalling pathways involved in EGFR/HER2 transactivation by VPAC receptors and suggest the potential usefulness of VIP receptor antagonists together with current antibodies against EGFR/HER2 and/or tyrosine kinase inhibitors for breast cancer therapy.

Single-agent lapatinib for HER2-overexpressing advanced or metastatic breast cancer that progressed on first- or second-line trastuzumab-containing regimens

BACKGROUND

This phase II study evaluated the efficacy and safety of lapatinib in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced or metastatic breast cancer that progressed during prior trastuzumab therapy.

PATIENTS AND METHODS

Women with stage IIIB/IV HER2-overexpressing breast cancer were treated with single-agent lapatinib 1250 or 1500 mg once daily after protocol amendment. Tumor response according to RECIST was assessed every 8 weeks. HER2 expression was assessed in tumor tissue by immunohistochemistry and FISH.

RESULTS

Seventy-eight patients were enrolled in the study. Investigator and independent review response rates [complete response (CR) or partial response (PR)] were 7.7% and 5.1%, and clinical benefit rates (CR, PR, or stable disease for >or=24 weeks) were 14.1% and 9.0%, respectively. Median time to progression was 15.3 weeks by independent review, and median overall survival was 79 weeks. The most common treatment-related adverse events were rash (47%), diarrhea (46%), nausea (31%), and fatigue (18%).

CONCLUSIONS

Single-agent lapatinib has clinical activity with manageable toxic effects in HER2-overexpressing breast cancer that progressed on trastuzumab-containing therapy. Studies of lapatinib-based combination regimens with chemotherapy and other targeted therapies in metastatic and earlier stages of breast cancer are warranted.

Technological advances in mucositis research: new insights and new issues

The last decade has seen a significant acceleration in the introduction of molecular tools used in cancer diagnosis and treatment. Driving factors have been the movement of advanced technologies from the laboratory to the clinic and the shift to a more genetically individualised patient approach. With this has followed an increased ability to study the toxic side effects of cancer treatment, some of which are newly emerging, by utilising many of the same technologies. Mucositis research in particular has reached a golden period of investigation and understanding of the pathobiological mechanisms that contribute to the development of the condition. This paper has selected a few of the emerging technologies that are highly relevant to mucositis research to discuss in detail. These technologies include target therapies, toxicogenomics, nanomedicine, pharmacogenetics and pharmacogenomics, with a particular focus on microarray technology. These technologies are critical to discuss in the context of mucositis research not only because they are widely applicable to cutting edge research, but they also provide opportunities for further advances both in the laboratory and clinical setting. In addition, some of these technologies have the potential to be implemented immediately in the field of mucositis research.