Survival benefits from lapatinib therapy in women with HER2-overexpressing breast cancer: a systematic review

Beyond RAS and BRAF: a target rich disease that is ripe for picking

Despite numerous breakthroughs in the understanding of colorectal cancer and identification of many oncogenic mutations, the treatment of metastatic colorectal cancer remains relatively more empiric than targeted. Testing for mutations in rat sarcoma virus (RAS) and rapidly growing fibrosarcoma (RAF) are routinely performed, though identification of these mutations currently offers little more than a negative predictive marker for response to EGFR inhibitor treatment and, in the case of RAF mutation, a poor prognostic indicator. Next-generation sequencing has identified both common and rare mutations in colorectal cancer that offer options for more advanced, targeted therapy. With so much research invested in these targets, the treatment of metastatic colorectal cancer stands to become much more personalized in the near future. This review describes several of the more promising targets that are currently being investigated in advanced colorectal cancer.

Pneumonitis and pulmonary fibrosis associated with breast cancer treatments

To review the available published data regarding the incidence, mechanisms of pathogenesis, clinical presentations and management of pneumonitis caused by anti-cancer treatments (radiotherapy (RT) and systemic agents) that are included in the guidelines of the treatment of breast cancer (BC) and address the issues on the current grading classification of pneumonitis. A literature search was performed between July and October 2013 using PubMed for papers published from January 1989 to October 2013. Any clinical trial, case report, case series, meta-analysis or systematic review that reported on pulmonary toxicity of any BC therapeutic modality was included (only papers published in English). Most of anticancer treatments currently used in the management of BC may induce some degree of pneumonitis that is estimated to have an incidence of 1-3 %. There is an obvious distinction between chemotherapy- and targeted treatment-related lung toxicity. Moreover, the current classification of pneumonitis needs to be modified as there is a clear diversity in grade 2. As pneumonitis is relatively common and reported as side effect of new anticancer agents, physicians need to be aware of the clinical and radiological manifestations of drug- and RT-induced toxicities in patients with BC. A key recommendation is the subdivision of grade 2 cases to two subgroups. We provide an algorithm, along with real life cases as managed in the breast Unit of Royal Marsden Hospital, with the aim to guide physicians in managing all possible eventualities that may come across in clinical practise.

A phase II, randomized, multicenter study evaluating the combination of lapatinib and vinorelbine in women with ErbB2 overexpressing metastatic breast cancer

Lapatinib is approved in combination with capecitabine for treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) who have progressed on prior trastuzumab in the metastatic setting. Vinorelbine is an important chemotherapy option for MBC. We evaluated efficacy and safety of lapatinib plus vinorelbine, compared with lapatinib plus capecitabine, in women with HER2-positive MBC. In this open-label, multicenter, phase II study, eligible patients (N = 112) were randomized 2:1 to lapatinib plus vinorelbine [(N = 75) 1,250 mg orally once daily (QD) continuously plus 20 mg/m(2)/day intravenously] or lapatinib plus capecitabine [(N = 37) 1,250 mg orally QD continuously plus 2,000 mg/m(2)/day orally, 2 doses]. The primary endpoint was progression-free survival (PFS). Other endpoints included overall survival (OS) and safety. Patients progressing within the study were given the option of crossover to the other treatment arm; time to second progression was an exploratory endpoint. Patient demographics, stratification, and prognostic factors were well balanced between treatments. Median PFS in both arms was 6.2 months [95 % confidence interval (CI) 4.2, 8.8 (lapatinib plus vinorelbine); 4.4, 8.3 (lapatinib plus capecitabine)]. Median OS on lapatinib plus vinorelbine was 24.3 months (95 % CI 16.4, NE) and 19.4 months (95 % CI 16.4, 27.2) on lapatinib plus capecitabine. In total, 42 patients opted to cross over; median PFS was 3.2 months (95 % CI 1.7, 5.1) on lapatinib plus vinorelbine and 4.0 months (95 % CI 2.1, 5.8) on lapatinib plus capecitabine. Lapatinib plus vinorelbine offers an effective treatment option for patients with HER2-overexpressing MBC, having displayed comparable efficacy and tolerability rates to lapatinib plus capecitabine.

Lapatinib plus chemotherapy or endocrine therapy (CET) versus CET alone in the treatment of HER-2-overexpressing locally advanced or metastatic breast cancer: systematic review and meta-analysis

BACKGROUND

This paper reports a systematic review and meta-analysis of all randomized controlled trials comparing the efficacy of lapatinib plus chemotherapy or endocrine therapy (CET) versus CET alone in human epidermal growth factor receptor 2-overexpressing (HER-2+) locally advanced or metastatic breast cancer.

METHODS

Several databases were searched, including MEDLINE, EMBASE, LILACS, and CENTRAL. The primary endpoints were progression-free survival and overall survival. The side effects of each treatment were analyzed. The data extracted from the studies were combined by using the hazard ratio or risk ratio with their corresponding 95% confidence interval (CI).

RESULTS

A total of 113 references were identified and screened. The final analysis included four trials comprising 1,073 patients with HER-2+. The overall response rate was higher in patients who received the combination of CET plus lapatinib (risk ratio 0.78; 95% CI 0.71-0.85; P < 0.00001) but with significant heterogeneity (χ(2) = 15.61, df = 3; P = 0.001; I(2) = 81%). This result remained favorable to the use of lapatinib when a random-effects model analysis was performed (risk ratio 0.76; 95% CI 0.62-0.94; P = 0.01). Progression-free survival was also higher in patients who received CET plus lapatinib (hazard ratio 0.57; 95% CI 0.49-0.66; P < 0.00001) with no heterogeneity detected on this analysis (χ(2) = 3.05; df = 3; P = 0.38; I(2) = 1%). Overall survival was significantly longer in patients who received CET plus lapatinib (hazard ratio 0.80; 95% CI 0.69-0.92; P = 0.002) without heterogeneity on this analysis (χ(2) = 1.26; df = 3; P = 0.74; I(2) = 0%). Regarding adverse events and severe toxicities (grade ≥3), the group receiving CET plus lapatinib had higher rates of neutropenia (risk ratio 2.08; 95% CI 1.64-2.62; P < 0.00001), diarrhea (risk ratio 4.82; 95% CI 3.14-7.41; P < 0.00001), and rash (risk ratio 8.03; 95% CI 2.46-26.23; P = 0.0006).

CONCLUSION

The combination of CET plus lapatinib increased the overall response rate, progression-free survival, and overall survival in patients with HER-2+ locally advanced or metastatic breast cancer.

Towards sustained silencing of HER2/neu in cancer by epigenetic editing

The human epidermal growth factor receptor-2 (HER2/neu/ERBB2) is overexpressed in several cancer types. Although therapies targeting the HER2/neu protein result in inhibition of cell proliferation, the anticancer effect might be further optimized by limiting HER2/neu expression at the DNA level. Towards this aim, epigenetic editing was performed to suppress HER2/neu expression by inducing epigenetic silencing marks on the HER2/neu promoter.HER2/neu expression and HER2/neu promoter epigenetic modification status were determined in a panel of ovarian and breast cancer cell lines. HER2/neu-overexpressing cancer cells were transduced to express a zinc finger protein (ZFP), targeting the HER2/neugene, fused to histone methyltransferases (G9a, SUV39-H1)/super KRAB domain (SKD). Epigenetic assessment of the HER2/neu promoter showed that HER2/neu-ZFP fused to G9a efficiently induced the intended silencing histone methylation mark (H3K9me2). Importantly, H3K9me2 induction was associated with a dramatic downregulation of HER2/neu expression in HER2/neu- overexpressing cells. Downregulation by SKD, traditionally considered transient in nature, was associated with removal of the histone acetylation mark (H3ac). The downregulation of HER2/neu by induced H3K9 methylation and/or reduced H3 acetylation was sufficient to effectively inhibit cellular metabolic activity and clonogenicity. Furthermore, genome-wide analysis indicated preferential binding of the ZFP to its target sequence. These results not only show that H3K9 methylation can be induced but also that this epigenetic mark was instructive in promoting downregulation of HER2/neu expression.

IMPLICATIONS

Epigenetic editing provides a novel (synergistic) approach to modulate expression of oncogenes.

Emerging approaches for treating HER2-positive metastatic breast cancer beyond trastuzumab

Because metastatic breast cancer (MBC) is incurable in most cases, the goals of treatment are improvement in quality of life, management of symptoms, and prolonged survival. The human epidermal growth factor receptor 2 (HER2) is overexpressed in up to 30% of breast tumors, and before the development of HER-targeted therapy, HER2 positivity was predictive of poorer clinical outcomes. Trastuzumab and pertuzumab (anti-HER2 monoclonal antibodies), lapatinib (a small molecule inhibitor of HER2 and the epidermal growth factor receptor [EGFR]) are approved for treating HER2-positive MBC in the United States. Although trastuzumab plus chemotherapy is currently regarded as the first-line standard of care for HER2-positive MBC, it is not without shortcomings; these include its association with certain adverse events (e.g. cardiotoxic effect) and development of resistance. A number of investigational agents that target HER2 and other members of that receptor family are in clinical development for patients with HER2-positive MBC whose disease has progressed on trastuzumab. In addition, in an effort to overcome treatment resistance, clinical trials are evaluating combination therapy (investigational HER-targeted agents with trastuzumab or lapatinib). This review discusses recently completed and ongoing phase II and III clinical trials of investigational HER-targeted agents in the setting of trastuzumab-progressive, HER2-positive MBC.

Advances in the management of HER2-positive advanced gastric and gastroesophageal junction cancer

In the past, patients with advanced or metastatic gastric or gastroesophageal junction cancer have had few treatment options and generally poor survival rates. The human epidermal growth factor receptor 2 (HER2) has been identified as a potential therapeutic target because of its overexpression or gene amplification in 6% to 35% of gastric or gastroesophageal junction cancers, although the methods of assessment and prognostic value of HER2 have been subject to debate. The phase III Trastuzumab for Gastric Cancer (ToGA) trial showed that adding the HER2-targeted humanized monoclonal antibody trastuzumab to chemotherapy significantly improves survival without negatively impacting quality of life in patients with advanced gastric or gastroesophageal junction cancer. As a result, trastuzumab is now the sole HER2-targeted therapy approved in several countries for this indication. The ToGA trial also demonstrated that patients who expressed higher levels of HER2 (determined by immunohistochemical screening) received the greatest benefit from trastuzumab therapy. This finding underlines the importance of accurate HER2 testing. Because of the unique characteristics of gastric cancer, a new gastric cancer-specific scoring system for HER2 expression was proposed during the ToGA trial. The aim of this review is to inform the gastroenterologist of the potential role of HER2-targeted therapy, to discuss the importance of accurate and reliable HER2 testing, and to discuss ongoing studies with HER2-targeted therapies that may have an impact on the future treatment of HER2-positive gastric cancer.

Combination drug delivery approaches in metastatic breast cancer

Disseminated metastatic breast cancer needs aggressive treatment due to its reduced response to anticancer treatment and hence low survival and quality of life. Although in theory a combination drug therapy has advantages over single-agent therapy, no appreciable survival enhancement is generally reported whereas increased toxicity is frequently seen in combination treatment especially in chemotherapy. Currently used combination treatments in metastatic breast cancer will be discussed with their challenges leading to the introduction of novel combination anticancer drug delivery systems that aim to overcome these challenges. Widely studied drug delivery systems such as liposomes, dendrimers, polymeric nanoparticles, and water-soluble polymers can concurrently carry multiple anticancer drugs in one platform. These carriers can provide improved target specificity achieved by passive and/or active targeting mechanisms.

Furanodienone induces cell cycle arrest and apoptosis by suppressing EGFR/HER2 signaling in HER2-overexpressing human breast cancer cells

PURPOSE

Overexpression of EGFR and HER2 is seen in breast cancers and results in poor prognosis and decreased patient survival. Clinically, EGFR and HER2 are effective therapeutic targets. The objective of this study is to investigate the in vitro effects of furanodienone, an active chemical component isolated from Rhizoma Curcumae, on the activation of EGFR/HER2 signaling, cell cycle, and apoptosis in HER2-overexpressing BT474 and SKBR3 cells.

METHODS

Cell growth was assessed by SRB protein assay. Cell cycle analysis was carried out by flow cytometry, and apoptosis was observed by Annexin V and DAPI staining. Effects of furanodienone on the activation of EGFR/HER2 signaling-related proteins were analyzed by western blotting.

RESULTS

Furanodienone inhibited cell growth in BT474 and SKBR3 cells. Furanodienone caused G1 arrest in BT474 cells and induced apoptosis in SKBR3 cells. Furanodienone interfered with EGFR/HER2 signaling in treated cells as shown by decreases in phosphorylated EGFR, HER2, Akt, Gsk3β and an increase in p27(kip1) protein. Accordingly, furanodienone inhibited EGF-induced phosphorylation of EGFR, HER2, Akt, and Gsk3β. EGFR-specific siRNA knockdown did not affect the cell growth inhibitory effect of furanodienone. On the contrary, specific siRNA knockdown of HER2 increased cellular resistance to furanodienone toxicity. In HER-2-deficient MDA-MB-231 cells, the transfection and expression of HER2 increased the sensitivity of cells to furanodienone toxicity.

CONCLUSION

Furanodienone inhibited EGFR/HER2 signaling pathway in BT474 and SKBR3 cells. More importantly, the effect of furanodienone was specifically dependent on HER2, but not EGFR, expression.

Inhibition of MCL-1 in breast cancer cells promotes cell death in vitro and in vivo

The present studies have examined approaches to suppress MCL-1 function in breast cancer cells, as a means to promote tumor cell death. Treatment of breast cancer cells with CDK inhibitors (flavopiridol; roscovitine) enhanced the lethality of the ERBB1 inhibitor lapatinib in a synergistic fashion. CDK inhibitors interacted with lapatinib to reduce MCL-1 expression and over-expression of MCL-1 or knock down of BAX and BAK suppressed drug combination lethality. Lapatinib-mediated inhibition of ERK1/2 and to a lesser extent AKT facilitated CDK inhibitor -induced suppression of MCL-1 levels. Treatment of cells with the BH3 domain / MCL-1 inhibitor obatoclax enhanced the lethality of lapatinib in a synergistic fashion. Knock out of MCL-1 and BCL-XL enhanced lapatinib toxicity to a similar extent as obatoclax and suppressed the ability of obatoclax to promote lapatinib lethality. Pre-treatment of cells with lapatinib or with obatoclax enhanced basal levels of BAX and BAK activity and further enhanced drug combination toxicity. In vivo tumor growth data in xenograft and syngeneic model systems confirmed our in vitro findings. Treatment of cells with CDK inhibitors enhanced the lethality of obatoclax in a synergistic fashion. Over-expression of MCL-1 or knock down of BAX and BAK suppressed the toxic interaction between CDK inhibitors and obatoclax. Obatoclax and lapatinib treatment or obatoclax and CDK inhibitor treatment or lapatinib and CDK inhibitor treatment radiosensitized breast cancer cells. Lapatinib and obatoclax interacted to suppress mammary tumor growth in vivo. Collectively our data demonstrate that manipulation of MCL-1 protein expression by CDK inhibition or inhibition of sequestering function MCL-1 by Obatoclax renders breast cancer cells more susceptible to BAX/BAK-dependent mitochondrial dysfunction and tumor cell death.