Aurora kinase A drives the evolution of resistance to third-generation EGFR inhibitors in lung cancer.

Although targeted therapies often elicit profound initial patient responses, these effects are transient due to residual disease leading to acquired resistance. How tumors transition between drug responsiveness, tolerance and resistance, especially in the absence of preexisting subclones, remains unclear. In epidermal growth factor receptor (EGFR)-mutant lung adenocarcinoma cells, we demonstrate that residual disease and acquired resistance in response to EGFR inhibitors requires Aurora kinase A (AURKA) activity. Nongenetic resistance through the activation of AURKA by its coactivator TPX2 emerges in response to chronic EGFR inhibition where it mitigates drug-induced apoptosis. Aurora kinase inhibitors suppress this adaptive survival program, increasing the magnitude and duration of EGFR inhibitor response in preclinical models. Treatment-induced activation of AURKA is associated with resistance to EGFR inhibitors in vitro, in vivo and in most individuals with EGFR-mutant lung adenocarcinoma. These findings delineate a molecular path whereby drug resistance emerges from drug-tolerant cells and unveils a synthetic lethal strategy for enhancing responses to EGFR inhibitors by suppressing AURKA-driven residual disease and acquired resistance

The role of APOBEC3B in lung tumor evolution and targeted cancer therapy resistance

In this study, the impact of the apolipoprotein B mRNA-editing catalytic subunit-like (APOBEC) enzyme APOBEC3B (A3B) on epidermal growth factor receptor (EGFR)-driven lung cancer was assessed. A3B expression in EGFR mutant (EGFRmut) non-small-cell lung cancer (NSCLC) mouse models constrained tumorigenesis, while A3B expression in tumors treated with EGFR-targeted cancer therapy was associated with treatment resistance. Analyses of human NSCLC models treated with EGFR-targeted therapy showed upregulation of A3B and revealed therapy-induced activation of nuclear factor kappa B (NF-κB) as an inducer of A3B expression. Significantly reduced viability was observed with A3B deficiency, and A3B was required for the enrichment of APOBEC mutation signatures, in targeted therapy-treated human NSCLC preclinical models. Upregulation of A3B was confirmed in patients with NSCLC treated with EGFR-targeted therapy. This study uncovers the multifaceted roles of A3B in NSCLC and identifies A3B as a potential target for more durable responses to targeted cancer therapy.</p

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Developmental events influence breast cancer risk: Insights from MYC, Stat5, and pregnancy

Epidemiological studies clearly demonstrate that the timing of normal developmental events, such as menarche, menopause, and a first full-term pregnancy, can significantly influence a woman\u27s lifetime risk of breast cancer. Moreover, the developmental stage of the breast at the time of exposure to a carcinogenic insult can also significantly influence breast cancer risk. At present, the biological mechanisms underlying these epidemiological observations are unknown. The goal of this thesis was to identify and characterize potential mechanisms through which mammary developmental processes might alter breast cancer risk. To accomplish this, we employed genetically engineered mice to determine whether mammary developmental events influence the effects of aberrant activation of the MYC oncogene. We determined that the effects of aberrant MYC activation are significantly modified by the developmental stage of the mammary gland at the time of exposure, due to alterations in Prlr-Jak2-Stat5 signaling. In addition, we found that the Prlr-Stat5 pathway plays a critical role in MYC-induced mammary tumorigenesis. Additional studies to investigate how developmental events influence breast cancer risk used gene expression profiling to identify persistent parity-induced changes in gene expression that correlate with the protective effects of an early first full-term pregnancy. Through this analysis, we identified a parity-related gene expression signature that is tightly linked with protection against carcinogen-induced breast cancer and is evolutionarily conserved in four genetically diverse inbred rat strains. Finally, we investigated the basis for the time-dependent effects of pregnancy on breast cancer risk: a first-full-term pregnancy early in life protects against breast cancer, whereas a first full-term pregnancy late in life increases breast cancer risk. Using a rat carcinogenesis model, we determined that it is the timing of pregnancy relative to an initiating carcinogenic event, rather than age at pregnancy per se, that determines whether a pregnancy will promote or protect against breast cancer. These findings have significant implications for how mammary developmental events affect breast cancer risk and suggest potential strategies for breast cancer prevention and treatment

Resiliency of Lung Cancers to EGFR Inhibitor Treatment Unveiled, Offering Opportunities to Divide and Conquer EGFR Inhibitor Resistance

The clinical success of EGF receptor (EGFR) inhibitors in patients with lung cancer is limited by the inevitable development of treatment resistance. Two reports in this issue of Cancer Discovery uncover additional mechanisms by which EGFR-mutant lung cancers escape from EGFR kinase inhibitor treatment. These findings pave the way for clinical testing of new rational therapeutic strategies to prevent or overcome resistance to EGFR kinase inhibitors in the clinic

Impact of concurrent genomic alterations in epidermal growth factor receptor ( EGFR )-mutated lung cancer

Comprehensive characterization of the genomic landscape of epidermal growth factor receptor (EGFR)-mutated lung cancers have identified patterns of secondary mutations beyond the primary oncogenic EGFR mutation. These include concurrent pathogenic alterations affecting p53 (60-65%), RTKs (5-10%), PIK3CA/KRAS (3-23%), Wnt (5-10%), and cell cycle (7-25%) pathways as well as transcription factors such as MYC and NKX2-1 (10-15%). The majority of these co-occurring alterations were detected or enriched in samples collected from patients at resistance to tyrosine kinase inhibitor (TKI) treatment, indicating a potential functional role in driving resistance to therapy. Of note, these co-occurring tumor genomic alterations are not necessarily mutually exclusive, and evidence suggests that multiple clonal and sub-clonal cancer cell populations can co-exist and contribute to EGFR TKI resistance. Computational tools aimed to classify, track and predict the evolution of cancer clonal populations during therapy are being investigated in pre-clinical models to guide the selection of combination therapy switching strategies that may delay the development of treatment resistance. Here we review the most frequently identified tumor genomic alterations that co-occur with mutated EGFR and the evidence that these alterations effect responsiveness to EGFR TKI treatment

Neoadjuvant Oncogene-Targeted Therapy in Early Stage Non–Small-Cell Lung Cancer as a Strategy to Improve Clinical Outcome and Identify Early Mechanisms of Resistance

Evaluations of resistance mechanisms to targeted treatments in non-small-cell lung cancer (NSCLC) are necessary for development of improved treatment after disease progression and to help delay progression of disease. Populations of cells that survive after initial treatment form the basis of resistance via outgrowth of resistant clones or activation of alternative signaling pathways. In this report we describe a clinical trial approach in which patients with epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), C-ros-1 proto-oncogene (ROS1), and hepatocyte growth factor receptor (MET) exon 14 alterations and early stage (IA-IIIA) NSCLC will be treated with induction EGFR tyrosine kinase inhibitor (TKI) or crizotinib, a TKI that inhibits ALK, ROS1, and MET. We will evaluate resected tumor samples for pathologic response to induction therapy, overall response rate, and disease-free survival. Additionally, we will assess patients for early evidence of resistance to targeted therapy in terms of activation of alternative signaling pathways and for identification of resistance clones in remnant cell populations