Overcoming Resistance to Targeted Therapies in Cancer

Discovery of a novel dual functional phenylpyrazole-styryl hybrid that induces apoptotic and autophagic cell death in bladder cancer cells

Unpleasant side effects and resistance development remained the Achilles heel of chemotherapy. Since low tumor-selectivity and monotonous effect of chemotherapy are closely related to such bottleneck, targeting tumor-selective multi-functional anticancer agents may be an ideal strategy in the search of new safer drugs. Herein, we report the discovery of compound 21, a nitro-substituted 1,5-diphenyl-3-styryl-1H-pyrazole that possesses dual functional characteristics. The 2D- and 3D-culture-based studies revealed that 21 not only could induce ROS-independent apoptotic and EGFR/AKT/mTOR-mediated autophagic cell deaths in EJ28 cells simultaneously but also has the ability in inducing cell death at both proliferating and quiescent zones of EJ28 spheroids. The molecular modelling analysis showed that 21 possesses EGFR targeting capability as it forms stable interactions in the EGFR active site. Together with its good safety profile in the zebrafish-based model, the present study showed that 21 is promising and may lead to the discovery of tumor-selective multi-functional anti-cancer agents.

Clinical and molecular feature-based nomogram model for predicting benefit from bevacizumab combined with first-generation EGFR-tyrosine kinase inhibitor (TKI) in EGFR-mutant advanced NSCLC

BACKGROUND

The combination of bevacizumab and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) could prolong progression-free survival (PFS) in patients with EGFR-mutant advanced non-small-cell lung cancer (NSCLC). Our study investigated the clinical and molecular factors that affect the efficacy of first-generation EGFR-TKI with or without bevacizumab and identify the subset of patients who can benefit from combination therapy.

METHODS

Our study included 318 patients with EGFR-mutant locally advanced/advanced NSCLC treated with either first-generation EGFR-TKI combined with bevacizumab (A+T; n = 159) or EGFR-TKI monotherapy (T; n = 159). Two nomogram models to predict PFS and overall survival (OS), respectively, were constructed using two factors that impact EGFR-TKI efficacy: metastatic site and presence of concurrent mutations. The study cohort was stratified into 2 cohorts for training (n = 176) and validation (n = 142) of the nomogram model. Using the median score from the nomogram, the patients were stratified into two groups to analyze their survival outcome.

RESULTS

The A+T group had significantly longer PFS (14.0 vs. 10.5 months; p < 0.001) and OS (37.0 vs. 26.0 months; p = 0.042) than the T group. Among the patients with concurrent mutations in tumor suppressor genes, those in the A+T group had significantly longer PFS and OS than the T group (PFS 14.5 vs. 8.0 months, p < 0.001; OS 39.0 vs. 20.0 months, p = 0.003). The higher scores from the nomograms were associated with the presence of brain/liver/pleural metastasis or concomitant gene mutations, which indicated a higher likelihood of shorter PFS and OS. The validation of the nomogram revealed that patients with lower scores had significantly longer PFS for the T group than those with higher scores (15.0 vs. 9.0 months, p = 0.002), but not for the A+T group (15.9 vs. 13.9 months, p = 0.256).

CONCLUSIONS

Using a nomogram, our study demonstrated that the addition of bevacizumab may enhance the therapeutic effectiveness of EGFR-TKI by overcoming the negative impact of certain clinical and molecular factors on the efficacy of EGFR-TKI.

MicroRNAs as Predictive Biomarkers of Resistance to Targeted Therapies in Gastrointestinal Tumors

The advent of precision therapies against specific gene alterations characterizing different neoplasms is revolutionizing the oncology field, opening novel treatment scenarios. However, the onset of resistance mechanisms put in place by the tumor is increasingly emerging, making the use of these drugs ineffective over time. Therefore, the search for indicators that can monitor the development of resistance mechanisms and above all ways to overcome it, is increasingly important. In this scenario, microRNAs are ideal candidate biomarkers, being crucial post-transcriptional regulators of gene expression with a well-known role in mediating mechanisms of drug resistance. Moreover, as microRNAs are stable molecules, easily detectable in tissues and biofluids, they are the ideal candidate biomarker to identify patients with primary resistance to a specific targeted therapy and those who have developed acquired resistance. The aim of this review is to summarize the major studies that have investigated the role of microRNAs as mediators of resistance to targeted therapies currently in use in gastro-intestinal neoplasms, namely anti-EGFR, anti-HER2 and anti-VEGF antibodies, small-molecule tyrosine kinase inhibitors and immune checkpoint inhibitors. For every microRNA and microRNA signature analyzed, the putative mechanisms underlying drug resistance were outlined and the potential to be translated in clinical practice was evaluated.

Melanoma Cell Resistance to Vemurafenib Modifies Inter-Cellular Communication Signals

The therapeutic success of BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) in BRAF-mutant melanoma is limited by the emergence of drug resistance, and several lines of evidence suggest that changes in the tumor microenvironment can play a pivotal role in acquired resistance. The present study focused on secretome profiling of melanoma cells sensitive or resistant to the BRAFi vemurafenib. Proteomic and cytokine/chemokine secretion analyses were performed in order to better understand the interplay between vemurafenib-resistant melanoma cells and the tumor microenvironment. We found that vemurafenib-resistant melanoma cells can influence dendritic cell (DC) maturation by modulating their activation and cytokine production. In particular, human DCs exposed to conditioned medium (CM) from vemurafenib-resistant melanoma cells produced higher levels of pro-inflammatory cytokines—that potentially facilitate melanoma growth—than DCs exposed to CM derived from parental drug-sensitive cells. Bioinformatic analysis performed on proteins identified by mass spectrometry in the culture medium from vemurafenib-sensitive and vemurafenib-resistant melanoma cells suggests a possible involvement of the proteasome pathway. Moreover, our data confirm that BRAFi-resistant cells display a more aggressive phenotype compared to parental ones, with a significantly increased production of interferon-γ, interleukin-8, vascular-endothelial growth factor, CD147/basigin, and metalloproteinase 2 (MMP-2). Plasma levels of CD147/basigin and MMP-2 were also measured before the start of therapy and at disease progression in a small group of melanoma patients treated with vemurafenib or vemurafenib plus cobimetinib. A significant increment in CD147/basigin and MMP-2 was observed in all patients at the time of treatment failure, strengthening the hypothesis that CD147/basigin might play a role in BRAFi resistance.

c-MYC Expression Is a Possible Keystone in the Colorectal Cancer Resistance to EGFR Inhibitors

Alterations in the transcriptional factor c-MYC could be involved in the anti-EGFR resistance in metastatic colorectal cancer (mCRC). The c-MYC expression was evaluated in 121 RAS and BRAF wild-type mCRC before treatment with anti-EGFR+Folfiri therapy and in 33 subsequent metastases collected during target therapy (TT) or in TT resistance phase. We analyzed the expression and the functional role of some c-MYC linked miRNAs (miR-31-3p, miR-143 and miR-145) in our patient group and in two CRC cell lines, also performing a c-MYC target PCR array. Patients with higher c-MYC expression (HME) showed a significant lower PFS and OS when compared to those with low c-MYC expression (LME). HME pattern was significantly more frequent in the metastases after TT and significantly associated to anti-EGFR molecular resistance alterations. We also found a significant correlation between the expression of the above-mentioned c-MYC linked miRNAs, c-MYC level and anti-EGFR resistance. Moreover, expression gene profiling pointed out the pivotal role of c-MYC in CRC-related cell-cycle, apoptosis, signal transduction and cell-growth pathways. c-MYC expression might distinguish patients with a lower PFS and OS in anti-EGFR treated mCRC. The individuation of some miRNAs involved in the c-MYC pathway regulation and the downstream c-MYC effector genes could provide a new possible target to overcome the anti-EGFR resistance in mCRC.

2'-Hydroxyflavanone inhibits the progression of pancreatic cancer cells and sensitizes the chemosensitivity of EGFR inhibitors via repressing STAT3 signaling

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, and chemotherapy is still an important treatment. It is urgent to develop new medicines because of the limitation and side effects of chemotherapy. 2'-Hydroxyflavanone (2HF) is a citrus-bioflavonoid that is considered to have anti-cancer efficacy. Compared to human pancreatic ductal epithelial cells hTERT-HPNE, more significant growth-inhibitory effects were seen in PDAC cells BxPC-3 and MIA PaCa-2. We showed that apoptosis was induced and that the cell cycle was arrested when cells were treated with 2HF. The expression of the molecular proteins cleaved PARP, cleaved Caspase3, Bax, Bcl-2, CyclinD1, and p27 changed correspondingly. Also, we observed anti-metastatic effects and changes in MMP9, E-cadherin, N-cadherin and Vimentin when cells were treated with a low dose of 2HF. Suppression of STAT3 and EGFR phosphorylation was also identified as a result of treatment with a combination of 2HF and EGFR inhibitors. The in vivo antitumor effects in KPC mice were consistent with those observed in vitro. 2HF has impactful anti-cancer efficacy and sensitizes human pancreatic cancer cells to EGFR inhibitors through the inhibition of STAT3.

Acquisition of chromosome instability is a mechanism to evade oncogene addiction

Chromosome instability (CIN) has been associated with therapeutic resistance in many cancers. However, whether tumours become genomically unstable as an evolutionary mechanism to overcome the bottleneck exerted by therapy is not clear. Using a CIN model of Kras‐driven breast cancer, we demonstrate that aneuploid tumours acquire genetic modifications that facilitate the development of resistance to targeted therapy faster than euploid tumours. We further show that the few initially chromosomally stable cancers that manage to persist during treatment do so concomitantly with the acquisition of CIN. Whole‐genome sequencing analysis revealed that the most predominant genetic alteration in resistant tumours, originated from either euploid or aneuploid primary tumours, was an amplification on chromosome 6 containing the cMet oncogene. We further show that these tumours are dependent on cMet since its pharmacological inhibition leads to reduced growth and increased cell death. Our results highlight that irrespective of the initial CIN levels, cancer genomes are dynamic and the acquisition of a certain level of CIN, either induced or spontaneous, is a mechanism to circumvent oncogene addiction.

A machine learning approach for somatic mutation discovery

Variability in the accuracy of somatic mutation detection may affect the discovery of alterations and the therapeutic management of cancer patients. To address this issue, we developed a somatic mutation discovery approach based on machine learning that outperformed existing methods in identifying experimentally validated tumor alterations (sensitivity of 97% versus 90 to 99%; positive predictive value of 98% versus 34 to 92%). Analysis of paired tumor-normal exome data from 1368 TCGA (The Cancer Genome Atlas) samples using this method revealed concordance for 74% of mutation calls but also identified likely false-positive and false-negative changes in TCGA data, including in clinically actionable genes. Determination of high-quality somatic mutation calls improved tumor mutation load-based predictions of clinical outcome for melanoma and lung cancer patients previously treated with immune checkpoint inhibitors. Integration of high-quality machine learning mutation detection in clinical next-generation sequencing (NGS) analyses increased the accuracy of test results compared to other clinical sequencing analyses. These analyses provide an approach for improved identification of tumor-specific mutations and have important implications for research and clinical management of cancer patients.

Rhein sensitizes human pancreatic cancer cells to EGFR inhibitors by inhibiting STAT3 pathway

Background

Rhein is a lipophilic anthraquinone extensively found in medicinal herbs. Emerging evidence suggests that rhein has significant antitumor effects, supporting its potential use as an antitumor agent. The IL6/STAT3 signaling pathway has been suggested as an attractive target for the discovery of novel cancer therapeutics.

Methods

The human pancreatic cancer cell lines AsPC-1, Patu8988T, BxPC-3 and PANC-1, and immunodeficient mice were chosen as models to study the effects of rhein. The potent antiproliferative and proapoptotic effects of rhein were examined by cell viability, cellular morphology, apoptosis and colony formation assays. The STAT3 luciferase report assay, immunostaining analysis and Western blot analysis revealed the inhibition of the IL6/STAT3 signaling axis.

Results

Apoptosis was induced by adjunctive use of rhein with epidermal growth factor receptor (EGFR) inhibitors in pancreatic cancer cells as verified by cell apoptosis analysis and changes in the expression level of apoptotic/anti-apoptotic proteins BCL-2, BAX, Caspase 3 and Cl-PARP. Suppression of the phosphorylation of STAT3 and EGFR were also observed as a result of the treatment with a combination of rhein and EGFR inhibitors. Most interestingly, it was found that rhein considerably sensitized cells to erlotinib, thus suppressing tumor growth in PANC-1 and BxPC-3 xenograft models. The in vivo anti-tumor effect was associated with increased apoptosis and combined inhibition of the STAT3 and EGFR pathways in tumor remnants.

Conclusions

Rhein sensitizes human pancreatic cancer cells to EGFR inhibitors through inhibition of STAT3. Taken together, the results indicate that rhein offers a novel blueprint for pancreatic cancer therapy, particularly when combined with EGFR inhibitors.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-1015-9) contains supplementary material, which is available to authorized users.

Functional significance of Hippo/YAP signaling for drug resistance in colorectal cancer

Colorectal cancer is a leading cause of cancer-related death worldwide. While early stage colorectal cancer can be removed by surgery, patients with advanced disease are treated by chemotherapy, with 5-Fluorouracil (5-FU) as a main ingredient. However, most patients with advanced colorectal cancer eventually succumb to the disease despite some responded initially. Thus, identifying molecular mechanisms responsible for drug resistance will help design novel strategies to treat colorectal cancer. In this study, we analyzed an acquired 5-FU resistant cell line, LoVo-R, and determined that elevated expression of YAP target genes is a major alteration in the 5-FU resistant cells. Hippo/YAP signaling, a pathway essential for cell polarity, is an important regulator for tissue homeostasis, organ size, and stem cells. We demonstrated that knockdown of YAP1 sensitized LoVo-R cells to 5-FU treatment in cultured cells and in mice. The relevance of our studies to colorectal cancer patients is reflected by our discovery that high expression of YAP target genes in the tumor was associated with an increased risk of cancer relapse and poor survival in a larger cohort of colorectal cancer patients who underwent 5-FU-related chemotherapy. Taken together, we demonstrate a critical role of YAP signaling for drug resistance in colorectal cancer.

BET inhibitors: a novel epigenetic approach

Epigenetics has been defined as 'the structural adaptation of chromosomal regions so as to register, signal or perpetuate altered activity states.' Currently, several classes of anticancer drugs function at the epigenetic level, including inhibitors of DNA methyltransferase, histone deacetylase (HDAC), lysine-specific demethylase 1, zeste homolog 2, and bromodomain and extra-terminal motif (BET) proteins.BET proteins have multiple functions, including the initiation and elongation of transcription and cell cycle regulation. In recent years, inhibitors of BET proteins have been developed as anticancer agents. These inhibitors exhibit selectivity for tumor cells by preferentially binding to superenhancers, noncoding regions of DNA critical for the transcription of genes that determine a cell's identity. Preclinical research on BET inhibitors has identified them as a potential means of targeting MYC.Early clinical trials with BET inhibitors have had mixed results, with few responses in both hematologic and solid tumors that tend to be short-lived. Toxicities have included severe, thrombocytopenia, fatigue, nausea, vomiting, and diarrhea; GI side-effects, fatigue, and low-grade dysgeusia have limited compliance. However, preclinical data suggest that BET inhibitors may have a promising future in combination with other agents. They appear to be able to overcome resistance to targeted agents and have strong synergy with immune checkpoint inhibitors as well as with multiple epigenetic agents, particularly HDAC inhibitors. In many instances, BET and HDAC inhibitors were synergistic at reduced doses, suggesting a potential means of avoiding the overlapping toxicities of the two drug classes.BET inhibitors provide a novel approach to epigenetic anticancer therapy. However, to date they appear to have limited efficacy as single agents. A focus on BET inhibitors in combination with other drugs such as targeted and/or as other epigenetic agents is warranted, due to limited monotherapy activity, including pharmacodynamic correlatives differential activity amongst select drug combinations.

Cancer reversion with oocyte extracts is mediated by cell cycle arrest and induction of tumour dormancy

Inducing stable control of tumour growth by tumour reversion is an alternative approach to cancer treatment when eradication of the disease cannot be achieved. The process requires re-establishment of normal control mechanisms that are lost in cancer cells so that abnormal proliferation can be halted. Embryonic environments can reset cellular programmes and we previously showed that axolotl oocyte extracts can reprogram breast cancer cells and reverse their tumorigenicity. In this study, we analysed the gene expression profiles of oocyte extract-treated tumour xenografts to show that tumour reprogramming involves cell cycle arrest and acquisition of a quiescent state. Tumour dormancy is associated with increased P27 expression, restoration of RB function and downregulation of mitogen-activated signalling pathways. We also show that the quiescent state is associated with increased levels of H4K20me3 and decreased H4K20me1, an epigenetic profile leading to chromatin compaction. The epigenetic reprogramming induced by oocyte extracts is required for RB hypophosphorylation and induction of P27 expression, both occurring during exposure to the extracts and stably maintained in reprogrammed tumour xenografts. Therefore, this study demonstrates the value of oocyte molecules for inducing tumour reversion and for the development of new chemoquiescence-based therapies.

Induction of anti-EGFR immune response with mimotopes identified from a phage display peptide library by panitumumab

The epidermal growth factor receptor (EGFR) is overexpressed in several epithelial tumors. Anti-EGFR humanized monoclonal antibodies, cetuximab and panitumumab, in combination with chemotherapy have improved the prognosis for patients with wild-type RAS tumors. To identify mimotopes of EGFR and develop mimotope-based EGFR vaccines, we screened a phage display peptide library with panitumumab. Two EGFR mimotopes P19 and P26, which could be recognized by panitumumab specifically, were isolated. To enhance the immune responses, we generated recombinant proteins of P19 or P26 fused to a heat-shock cognate protein 70 (Hsc70), and evaluated the efficacy of Hsc70-P19 and Hsc70-P26 as vaccines in vivo. Immunization with Hsc70-P19 or Hsc70-P26 fusion protein stimulated the immune system to produce specific antibodies against peptides as well as EGFR. Moreover, antibodies elicited against mimotopes could induce antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), and inhibit the proliferation of EGFR-overexpressing A431 cells. Treatment with Hsc70-P19 and Hsc70-P26 significantly reduced tumor growth in BALB/c transplantable lung cancer models. Although there was no sequence homology between the phage-derived peptides and EGFR by alignments, both peptides mimic the conformational structure of EGFR binding to panitumumab. In conclusion, the mimotopes we identified from phage display peptide library could be promising candidate vaccines for active anti-EGFR immunotherapy against cancers.

The synthetic lethal killing of RAD54B-deficient colorectal cancer cells by PARP1 inhibition is enhanced with SOD1 inhibition

Colorectal cancer (CRC) is a leading cause of cancer-related death throughout the world. Despite improved screening efforts, most CRCs are diagnosed at late stages when surgery alone is not curative. Moreover, the low 5-year survival rate (~8-13%) for those living with stage IV CRC highlights the need for better treatment options. Many current chemotherapeutic approaches are non-specific and associated with side effects due to their tendency to target both normal and cancer cells. To address this issue, synthetic lethal (SL) approaches are now being explored in cancer and are defined as the lethal combination of two independently viable mutations/deletions. From a therapeutic perspective, SL interactors of genes mutated in cancer serve as candidate drug targets. The present study focuses on RAD54B, a gene that is aberrantly expressed in many cancer types, including CRC. We show that PARP1 silencing or inhibition (BMN673 or Olaparib) leads to selective killing within RAD54B-deficient cells relative to controls, and is accompanied by increases in γ-H2AX (a surrogate marker of DNA double strand breaks) and cleaved Caspase-3 (an apoptotic indicator). We further show that BMN673 synergizes with LCS-1 (an inhibitor of an established RAD54B SL interactor) to induce enhanced killing in RAD54B-deficient cells. Collectively, these data identify RAD54B and PARP1 as SL interactors, and thus reveal PARP1 as a novel candidate drug target in RAD54B-deficient CRCs. These findings further show that combinatorial chemotherapies involving multiple SL targets may promote synergistic killing within cancer cells, a strategy that may hold potential in many cancer contexts.

Acquired nintedanib resistance in FGFR1-driven small cell lung cancer: role of endothelin-A receptor-activated ABCB1 expression

Genomically amplified fibroblast growth factor receptor 1 (FGFR1) is an oncogenic driver in defined lung cancer subgroups and predicts sensibility against FGFR1 inhibitors in this patient cohort. The FGFR inhibitor nintedanib has recently been approved for treatment of lung adenocarcinoma and is currently evaluated for small cell lung cancer (SCLC). However, tumor recurrence due to development of nintedanib resistance might occur. Hence, we aimed at characterizing the molecular mechanisms underlying acquired nintedanib resistance in FGFR1-driven lung cancer. Chronic nintedanib exposure of the FGFR1-driven SCLC cell line DMS114 (DMS114/NIN) but not of two NSCLC cell lines induced massive overexpression of the multidrug-resistance transporter ABCB1. Indeed, we proved nintedanib to be both substrate and modulator of ABCB1-mediated efflux. Importantly, the oncogenic FGFR1 signaling axis remained active in DMS114/NIN cells while bioinformatic analyses suggested hyperactivation of the endothelin-A receptor (ET_AR) signaling axis. Indeed, ET_AR inhibition resensitized DMS114/NIN cells against nintedanib by downregulation of ABCB1 expression. PKC and downstream NFκB were identified as major downstream players in ET_AR-mediated ABCB1 hyperactivation. Summarizing, ABCB1 needs to be considered as a factor underlying nintedanib resistance. Combination approaches with ET_AR antagonists or switching to non-ABCB1 substrate FGFR inhibitors represent innovative strategies to manage nintedanib resistance in lung cancer.

Molecular Basis for Necitumumab Inhibition of EGFR Variants Associated with Acquired Cetuximab Resistance

Acquired resistance to cetuximab, an antibody that targets the EGFR, impacts clinical benefit in head and neck, and colorectal cancers. One of the mechanisms of resistance to cetuximab is the acquisition of mutations that map to the cetuximab epitope on EGFR and prevent drug binding. We find that necitumumab, another FDA-approved EGFR antibody, can bind to EGFR that harbors the most common cetuximab-resistant substitution, S468R (or S492R, depending on the amino acid numbering system). We determined an X-ray crystal structure to 2.8 Å resolution of the necitumumab Fab bound to an S468R variant of EGFR domain III. The arginine is accommodated in a large, preexisting cavity in the necitumumab paratope. We predict that this paratope shape will be permissive to other epitope substitutions, and show that necitumumab binds to most cetuximab- and panitumumab-resistant EGFR variants. We find that a simple computational approach can predict with high success which EGFR epitope substitutions abrogate antibody binding. This computational method will be valuable to determine whether necitumumab will bind to EGFR as new epitope resistance variants are identified. This method could also be useful for rapid evaluation of the effect on binding of alterations in other antibody/antigen interfaces. Together, these data suggest that necitumumab may be active in patients who are resistant to cetuximab or panitumumab through EGFR epitope mutation. Furthermore, our analysis leads us to speculate that antibodies with large paratope cavities may be less susceptible to resistance due to mutations mapping to the antigen epitope. Mol Cancer Ther; 17(2); 521-31. ©2017 AACR.

Addition of bevacizumab for malignant pleural effusion as the manifestation of acquired EGFR-TKI resistance in NSCLC patients

This study aimed to investigate the role of bevacizumab in patients with advanced non-small cell lung cancer (NSCLC) who had developed acquired resistance to EGFR-TKIs therapy that manifested as malignant pleural effusion (MPE). In total, 86 patients were included. 47 patients received bevacizumab plus continued EGFR-TKIs and 39 patients received bevacizumab plus chemotherapy. The curative efficacy rate for MPE in bevacizumab plus EGFR-TKIs group was significantly higher than that in bevacizumab plus chemotherapy group (89.4% vs. 64.1%, respectively; P = 0.005). Patients in bevacizumab plus EGFR-TKIs group had longer progression-free survival (PFS) than those in bevacizumab plus chemotherapy group (median PFS 6.3 vs. 4.8 months, P = 0.042). While patients with acquired T790M mutation in bevacizumab plus EGFR-TKIs group had a significantly longer PFS than those in bevacizumab plus chemotherapy group (median PFS 6.9 vs. 4.6 months, P = 0.022), patients with negative T790M had similar PFS (median PFS 6.1 vs. 5.5 months, P = 0.588). Overall survival (OS) was similar between two groups (P = 0.480). In multivariate analysis, curative efficacy was an independent prognostic factor (HR 0.275, P = 0.047). In conclusion bevacizumab plus EGFR-TKIs could be a valuable treatment for NSCLC patients presenting with MPE upon resistant to EGFR-TKIs therapy, especially for those with acquired T790M mutation.

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.

Reviving the guardian of the genome: Small molecule activators of p53

The tumor suppressor p53 is one of the most important proteins for protection of genomic stability and cancer prevention. Cancers often inactivate it by either mutating its gene or disabling its function. Thus, activating p53 becomes an attractive approach for the development of molecule-based anti-cancer therapy. The past decade and half have witnessed tremendous progress in this area. This essay offers readers with a grand review on this progress with updated information about small molecule activators of p53 either still at bench work or in clinical trials.

Inhibition of the fibroblast growth factor receptor (FGFR) pathway: the current landscape and barriers to clinical application

The fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) is a tyrosine kinase signaling pathway that has a fundamental role in many biologic processes including embryonic development, tissue regeneration, and angiogenesis. Increasing evidence indicates that this pathway plays a critical role in oncogenesis via gene amplification, activating mutations, or translocation in tumors of various histologies. With multiplex sequencing technology, the detection of FGFR aberrations has become more common and is tied to cancer cell proliferation, resistance to anticancer therapies, and neoangiogenesis. Inhibition of FGFR signaling appears promising in preclinical studies, suggesting a pathway of clinical interest in the development of targeted therapy. Phase I trials have demonstrated a manageable toxicity profile. Currently, there are multiple FGFR inhibitors under study with many non-selective (multi-kinase) inhibitors demonstrating limited clinical responses. As we progress from the first generation of non-selective drugs to the second generation of selective FGFR inhibitors, it is clear that FGFR aberrations do not behave uniformly across cancer types; thus, a deeper understanding of biomarker strategies is undoubtedly warranted. This review aims to consolidate data from recent clinical trials with a focus on selective FGFR inhibitors. As Phase II clinical trials emerge, concentration on patient selection as it pertains to predicting response to therapy, feasible methods for overcoming toxicity, and the likelihood of combination therapies should be utilized. We will also discuss qualities that may be desirable in future generations of FGFR inhibitors, with the hope that overcoming these current barriers will expedite the availability of this novel class of medications.

Talimogene Laherparepvec (T-VEC) and Other Oncolytic Viruses for the Treatment of Melanoma

Many mammalian viruses have properties that can be commandeered for the treatment of cancer. These characteristics include preferential infection and replication in tumor cells, the initiation of tumor cell lysis, and the induction of innate and adaptive anti-tumor immunity. Furthermore, viruses can be genetically engineered to reduce pathogenicity and increase immunogenicity resulting in minimally toxic therapeutic agents. Talimogene laherparepvec (T-VEC; Imlygic™), is a genetically modified herpes simplex virus, type 1, and is the first oncolytic virus therapy to be approved for the treatment of advanced melanoma by the US FDA. T-VEC is attenuated by the deletion of the herpes neurovirulence viral genes and enhanced for immunogenicity by the deletion of the viral ICP47 gene. Immunogenicity is further supported by expression of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) gene, which helps promote the priming of T cell responses. T-VEC demonstrated significant improvement in durable response rate, objective response rate, and progression-free survival in a randomized phase III clinical trial for patients with advanced melanoma. This review will discuss the optimal selection of patients for such treatment and describe how therapy is optimally delivered. We will also discuss future directions for oncolytic virus immunotherapy, which will likely include combination T-VEC clinical trials, expansion of T-VEC to other types of non-melanoma skin cancers, and renewed efforts at oncolytic virus drug development with other viruses.

Role of mathematical medicine in gastrointestinal carcinoma: Current status and perspectives

Mathematical medicine has already played an important role in clinical and basic research as a major interdisciplinary branch of medicine. Mathematical medicine has an important role not only in imaging diagnosis, image storage and transmission in gastrointestinal (GI) cancer, but also in tumor precision therapy. Specifically, in the field of minimally invasive treatment such as precise ablation, 3-dimension modeling, navigation, and surgical simulation significantly improve the therapeutic safety and efficiency in GI cancer. In addition, in the era of big data, data analysis and individualized therapy using mathematical medicine will become a trend in the future, offering an effective method for diagnosing and treating GI cancer and promoting clinical and scientific research.

Long noncoding RNA CRNDE functions as a competing endogenous RNA to promote metastasis and oxaliplatin resistance by sponging miR-136 in colorectal cancer

Colorectal neoplasia differentially expressed (CRNDE) is a novel gene recognized as a long noncoding RNA (lncRNA) that is highly elevated in colorectal cancer and many other solid tumors but its functions on metastasis and oxaliplatin (OXA) resistance are unknown. In our study, we confirmed the upregulation of CRNDE in both primary specimens from colorectal cancer patients and colorectal cancer cell lines. Knockdown of CRNDE expression inhibited the migration and invasion potency of colorectal cancer cells with no effect on cell apoptosis. Overexpression of CRNDE promoted the migration and invasion potency of colorectal cancer cells. Furthermore, we found that CRNDE conferred chemoresistance in colorectal cancer cells. Knockdown of CRNDE with OXA treatment decreased cell viability and promoted DNA damage and cell apoptosis, while the overexpression of CRNDE with OXA treatment reduced DNA damage and cell apoptosis. Further in-depth mechanistic studies revealed that CRNDE functioned as a competing endogenous RNA for miR-136, led to the de-repression of its endogenous target, E2F transcription factor 1 (E2F1). Overall, our findings demonstrate that CRNDE functions as a competing endogenous RNA to promote metastasis and OXA resistance by sponging miR-136 in colorectal cancer.

Immuno-oncology for renal cell carcinoma treatment: future perspectives for combinations and sequences with molecularly targeted agents

INTRODUCTION

From a theoretical viewpoint, combining molecularly targeted agents endowed with antiangiogenic properties with immunotherapy makes sense in treatment of metastatic renal cell carcinoma (RCC); this neoplasm is highly angiogenesis-dependent, as well as potentially immunogenic. Areas covered: The authors performed a literature search looking for clinical trials aimed at evaluating efficacy and tolerability of combinations (or sequences) of molecularly targeted agents and different immunotherapeutic approaches in metastatic RCC. Expert opinion: Combinations of molecularly targeted agents with old immunotherapeutics (i.e., cytokines) seem to add little to the presently available treatment standards (mainly monotherapy with targeted agents). Newer combinations with immune checkpoint inhibitors are promising but cumulative toxicity is an important issue, although highly dependent on the different companion drugs. Combinations with vaccines are ongoing, but first available data are not encouraging. A more thorough comprehension of the complex effects of these combinations on the immune system is mandatory to develop less empiric treatments.

Molecular mechanisms of HLA class I-mediated immune evasion of human tumors and their role in resistance to immunotherapies

Although the human immune system can recognize and eradicate tumor cells, tumors have also been shown to develop different strategies to escape immune surveillance, which has been described for the first time in different mouse models. The evasion of immune recognition was often associated with a poor prognosis and reduced survival of patients. During the last years the molecular mechanisms, which protect tumor cells from this immune attack, have been identified and appear to be more complex than initially expected. However, next to the composition of cellular, soluble and physical components of the tumor microenvironment, the tumor cells changes to limit immune responses. Of particular importance are classical and non-classical human leukocyte antigen (HLA) class I antigens, which often showed a deregulated expression in cancers of distinct origin. Furthermore, HLA class I abnormalities were linked to defects in the interferon signaling, which have both been shown to be essential for mounting immune responses and are involved in resistances to T cell-based immunotherapies. Therefore this review summarizes the expression, regulation, function and clinical relevance of HLA class I antigens in association with the interferon signal transduction pathway and its role in adaptive resistances to immunotherapies.

Precision medicine for hepatocellular carcinoma: Perspectives and obstacles

Hepatocellular carcinoma (HCC) is one of the most common cancers in China. HCC patients have a poor prognosis due to the lack of effective drugs. The marketing of sorafenib in 2007 has terminated the history that there is no effective drug for HCC. Unfortunately, sorafenib prolongs the survival of advanced HCC patients by only 2-3 mo, and remains the unique systemic drug as no alternative effective agents have been demonstrated to be superior to sorafenib in treating HCC. Precision medicine, a novel concept and medicinal model, has recently emerged and been spreading globally, with the development of gene sequencing techniques, bioinformatics, big data and so on. Detecting, analyzing, verifying and utilizing the specific tumor biomarkers with the advanced technology have made it possible to apply "personalized and precision therapy" in the treatment of advanced HCC. In the present article we summarize the recent progress of HCC therapy under the guidance of precision medicine, and analyze the major obstacles for its clinical application, with an aim to provide some new clues for clinicians and researchers engaged in the clinical and basic research of HCC.

The steady progress of targeted therapies, promising advances for lung cancer

Lung cancer remains one of the most complex and challenging cancers, being responsible for almost a third of all cancer deaths. This grim picture seems however to be changing, for at least a subset of lung cancers. The number of patients who can benefit from targeted therapies is steadily increasing thanks to the progress made in identifying actionable driver lesions in lung tumours. The success of the latest generation of EGFR and ALK inhibitors in the clinic not only illustrates the value of targeted therapies, but also shows how almost inevitably drug resistance develops. Therefore, more sophisticated approaches are needed to achieve long-term remissions. Although there are still significant barriers to be overcome, technological advances in early detection of relevant mutations and the opportunity to test new drugs in predictive preclinical models justify the hope that we will overcome these obstacles.

Role of IL-2 in cancer immunotherapy

Interleukin-2 (IL-2) is one of the key cytokines with pleiotropic effects on immune system. It has been approved for the treatment of metastatic renal cell carcinoma and metastatic melanoma. Recent progress has been made in our understanding of IL-2 in regulating lymphocytes that has led to exciting new directions for cancer immunotherapy. While improved IL-2 formulations might be used as monotherapies, their combination with other anticancer immunotherapies, such as adoptive cell transfer regimens, antigen-specific vaccination, and blockade of immune checkpoint inhibitory molecules, for example cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1) mono-antibodies, would held the promise of treating metastatic cancer. Despite the comprehensive studies of IL-2 on immune system have established the application of IL-2 for cancer immunotherapy, a number of poignant obstacles remain for future research. In the present review, we will focus on the key biological features of IL-2, current applications, limitations, and future directions of IL-2 in cancer immunotherapy.

CT scan prior to radiotherapy in unresectable, locally advanced, non-small cell carcinoma of the lung: is it always necessary?

PURPOSE

There is broad consensus regarding evaluating response to chemotherapy (CHT) by means of computerized tomography (CT) in patients with localized or locally advanced non-small cell lung carcinoma (NSCLC). We present a study comparing the usefulness of CT versus chest X-ray (XR) and clinical findings when indicating radiotherapy (RT) following CHT.

METHODS

Ninety-eight of 150 subjects with unresectable locally advanced NSCLC were blindly and independently evaluated by XR and CT, with pairs of chest XR and CT (before and after CHT). A null hypothesis (H0) was established of the conditioned probability of detecting progression by CT and not by XR of 10 % or more, with a statistical power of 80 %.

RESULTS

Sensitivity, specificity, positive and negative predictive value of XR versus CT were 98, 89, 99, and 80 % respectively. A 4 % (p = 0.0451) probability of improvement of CT versus XR was calculated, enabling the H0 to be ruled out.

CONCLUSION

The CT failed to prove to be significantly superior to the chest XR + clinical picture in indicating a change in treatment approach in patients with unresectable locally advanced NSCLC after CHT.