Clinical significance of p95HER2 overexpression, PTEN loss and PI3K expression in p185HER2-positive metastatic breast cancer patients treated with trastuzumab-based therapies

Breaking the Silence of Tumor Response: Future Prospects of Targeted Radionuclide Therapy

Therapy-induced tumor resistance has always been a paramount hurdle in the clinical triumph of cancer therapy. Resistance acquired by tumor through interventions of chemotherapeutic drugs, ionizing radiation, and immunotherapy in the patientsis a severe drawback and major cause of recurrence of tumor and failure of therapeutic responses. To counter acquired resistance in tumor cells, several strategies are practiced such as chemotherapy regimens, immunotherapy, and immunoconjugates, but the outcome is very disappointing for the patients as well as clinicians. Radionuclide therapy using alpha or beta-emitting radionuclide as payload became state-of-the-art for cancer therapy. With the improvement in dosimetric studies, development of high-affinity target molecules, and design of several novel chelating agents which provide thermodynamically stable complexes in vivo, the scope of radionuclide therapy has increased by leaps and bounds. Additionally, radionuclide therapy along with the combination of chemotherapy is gaining importance in pre-clinics, which is quite encouraging. Thus, it opens an avenue for newer cancer therapy modalities where chemotherapy, radiation therapy, and immunotherapy are unable to break the silence of tumor response. This article describes, in brief, the causes of tumor resistance and discusses the potential of radionuclide therapy to enhance tumor response.

Selected updates in molecular and genomic pathology of esophageal cancer

Recent years have seen rapid advances in the field of molecular and genomic pathology that have not only improved understanding of esophageal carcinogenesis and tumor immune environment in general but also have reshaped pathology practice and clinical management. In this article, we provide updates on three topics (1) human epidermal growth factor receptor 2, the first and most important biomarker in targeted therapy of esophageal cancer; (2) programmed death 1/programmed death ligand 1, recent biomarkers that have shown promise in treating both esophageal adenocarcinoma and esophageal squamous cell carcinoma; and (3) human papillomavirus involvement in esophageal carcinogenesis, one of the most debated topics in the field, discussed here with a renewed understanding from recent genomic and molecular data.

A new mechanism of trastuzumab resistance in gastric cancer: MACC1 promotes the Warburg effect via activation of the PI3K/AKT signaling pathway

Background

Trastuzumab, a humanized antibody targeting HER2, exhibits remarkable therapeutic efficacy against HER2-positive gastric cancer. However, recurrent therapeutic resistance presents revolutionary claims. Warburg effect and AKT signaling pathway was involved in the resistance to trastuzumab. Our previous studies have demonstrated that overexpression of metastasis associated with the colon cancer 1 (MACC1) predicted poor prognosis of GC and promoted tumor cells proliferation and invasion. In this study, we found that MACC1 was significantly upregulated in trastuzumab-resistant cell lines. Besides, downregulation of MACC1 reversed this resistance.

Methods

The effect of trastuzumab and glycolysis inhibitor combination on cell viability, apoptosis, and cell metabolism was investigated in vitro using established trastuzumab-resistant GC cell lines. We assessed the impact of trastuzumab combined with oxamate on tumor growth and metabolism in an established xenograft model of HER2-positive GC cell lines.

Results

Here, we found that MACC1 was significantly upregulated in trastuzumab-resistant cell lines. Besides, downregulation of MACC1 in trastuzumab-resistant cells reversed this resistance. Overexpression of MACC1-induced trastuzumab resistance, enhanced the Warburg effect, and activated the PI3K/AKT signaling pathway, while downregulation of MACC1 presented the opposite effects. Moreover, when the PI3K/AKT signaling pathway was inhibited, the effects of MACC1 on resistance and glycolysis were diminished. Our findings indicated that MACC1 promoted the Warburg effect mainly through the PI3K/AKT signaling pathway, which further enhanced GC cells trastuzumab resistance.

Conclusions

Our results indicate that co-targeting of HER2 and the Warburg effect reversed trastuzumab resistance in vitro and in vivo, suggesting that the combination might overcome trastuzumab resistance in MACC1-overexpressed, HER2-positive GC patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0302-1) contains supplementary material, which is available to authorized users.

Partial PTEN deletion is linked to poor prognosis in breast cancer

BACKGROUND

Deletions of chromosome 10q23, including the PTEN (phosphatase and tensin homolog) locus, are known to occur in breast cancer, but systematic analyses of its clinical relevance are lacking.

METHODS

We thus analyzed a tissue microarray (TMA) with 2,197 breast cancers by fluorescence in-situ hybridization (FISH) using a PTEN-specific probe.

RESULTS

PTEN deletions were detected in 19% of no special type, 9% of lobular, 4% of tubular cancers and 46% in carcinomas with medullary features. 98.7% of deletions were heterozygous and only 1.3% were homozygous. PTEN deletion was significantly linked to advanced tumor stage (p=0.0054), high-grade (p<0.0001), high tumor cell proliferation (Ki67 Labeling Index; p<0.0001), and shortened overall survival (p=0.0090). PTEN deletions were inversely associated with features of luminal type breast cancers (ER/PR positivity; p<0.0001 each, and CCND1 amplification; p=0.0020). PTEN deletions were also strongly linked to amplification of genes involved in the PTEN/AKT pathway such as MYC (p=0.0430) and HER2 (p=0.0065). Remarkably the combined analysis of MYC, HER2, CCND1 and PTEN aberrations suggested that aberrations of multiple PTEN/AKT pathway genes have a strong additive effect on breast cancer prognosis. While cancers with one of these aberrations behaved only marginally different from cancers with none, disease outcome was markedly worse in cancers with two or more aberrations as compared to those with only one aberration (p=0.0002). In addition, the particularly poor prognosis of patients with HER2 amplification and PTEN deletions challenges the concept of PTEN deletions interfering with trastuzumab therapy.

CONCLUSION

PTEN deletion occurs in a relevant fraction of breast cancers, and is linked to aggressive tumor behavior. Reduced PTEN function cooperates with MYC and HER2 activation in conferring aggressive phenotype to cancer cells.

The predictive and prognostic role of phosphatase phosphoinositol-3 (PI3) kinase (PIK3CA) mutation in HER2-positive breast cancer receiving HER2-targeted therapy: a meta-analysis

The association between PIK3CA mutation and resistance to anti-HER2 therapy (AHT) is not precisely defined. This meta-analysis intended to explore the clinical utility of PIK3CA mutation in HER2-positive breast cancer treated with AHT. Literature search identified 19 eligible studies. There were 1720 patients with advanced, 828 with early and 1290 patients treated in the neoadjuvant setting. In metastatic breast cancer, AHT showed no differential objective response benefit between the wild type (WT) and the mutated type (MT) PIK3CA subgroups (odds ratio [OR] = 1.09; 95 % CI 0.60-2.00; P = 0.78). AHT favorable affected progression-free survival (PFS) irrespective of PIK3CA mutation. There was no PFS difference between WT and MT regardless of the offered therapy. In early breast cancer, trastuzumab combined with the same chemotherapy conferred consistent relapse-free survival benefit in WT and MT subgroups (WT: HR = 0.59; 95 % CI 0.44-0.80; P < 0.001 vs. MT: HR = 0.42; 95 % CI 0.24-0.74; P < 0.001). In the neoadjuvant setting, AHT-based therapy produced a 72 % higher pathologic complete response (pCR) rate in WT as compared with that in MT PIK3CA tumors (OR = 1.72; 95 % CI 1.29-2.13; P < 0.001). In that setting, there was no disease-free or overall survival difference based on PIK3CA mutational status. In this meta-analysis, AHT did not achieve differential benefit according to PIK3CA mutation in HER2-positive metastatic or early breast cancer; however, in the neoadjuvant setting, patients harboring WT PIK3CA tumors attained a higher pCR rate.

Monitoring Trastuzumab Resistance and Cardiotoxicity: A Tale of Personalized Medicine

While approval of trastuzumab, a recombinant monoclonal antibody directed against HER2, along with a diagnostic kit to detect breast cancers which are positive for HER2 overexpression, has advanced a new era of stratified and personalized medicine, it also created several challenges to our scientific and clinical practice. These problems include trastuzumab resistance and trastuzumab-induced cardiotoxicity. In this review, we will summarize data from the literature regarding mechanisms of trastuzumab resistance and trastuzumab-induced cardiotoxicity and present some promising model systems that may advance our understanding of these mechanisms. Our discussion will include development of circulating tumor cells and circulating tumor DNA for monitoring tumor burden, of patient-derived xenograft models for preclinical testing of novel therapies, and of novel therapeutic strategies for trastuzumab-resistance and possible integration of these strategies in the design of co-clinical studies for testing in relevant patient subpopulations.

Strategies to overcome trastuzumab resistance in HER2-overexpressing breast cancers: focus on new data from clinical trials

Breast cancers over-express the human epidermal growth factor receptor 2 (HER2) in about 15% of patients. This transmembrane tyrosine kinase receptor activates downstream signaling pathways and leads to proliferation of cancer cells. Trastuzumab, an anti-HER2 monoclonal antibody, improves outcome in women with early and metastatic breast cancer. Resistance to trastuzumab involves the phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway, truncation of the Her2 receptor or lack of immune response. The last decade has seen major advances in strategies to overcome resistance to trastuzumab. This includes the development of antibody-drug conjugates, dual HER2 inhibition strategies, inhibition of PI3K/mTOR pathway and development of modulators of immune checkpoints.