PI3K Mutations Research Articles

Abstract 1212: Studying cancer drug resistance in patient derived xenograft tumor models

Abstract Anti-cancer drugs, either targeted therapies or cytotoxic chemotherapies, have proven to be effective in treating certain cancer patients. However, in most cases, tumors recur and become resistant to the treatment after a period of time. There are urgent needs to understand the underlying drug resistance mechanisms, to discover drug resistance targets and drug resistance biomarkers and to develop new therapies or combination therapies to tackle this widely occurring clinical problem. Currently the main approaches to study cancer drug resistance include analyzing clinical samples and developing drug resistance models in vitro. Numerous potential resistance mechanisms have been revealed. However, validation of these findings in a clinical-like setting and to test therapies in preclinical studies requires in vivo tumor models of drug resistance. At GenenDesign, we have developed cancer drug resistance PDX tumor models through short term drug testing or long term treatment of xenograft tumor mice. Cancer drugs investigated in our studies include major classes of targeted therapeutic modalities such as Her2 inhibitors, EGFR inhibitors, FGFR inhibitors and cMet/ALK inhibitors, as well as several standard of care (SoC) chemotherapies. From these studies, we have identified de novo resistance models, acquired resistance models and reversible resistance models in multiple cancer types including lung cancer and gastric cancer. In analyzing more than a dozen of Her2 positive but Herceptin resistance PDX models, we have uncovered molecular abnormalities such as Pten deletion, PI3K mutation, amplification of EGFR, cMet and cyclin E, which have been reported previously to be associated with Herceptin resistance in early studies. Studies are on-going to test whether combination therapies will be effective in overcoming Herceptin resistance. In drug response profiling of our PDX models, we also found wide spread phenotypical and functional heterogeneity in individual tumors. The heterogeneity within each tumor, in some cases, contributed to evolving of drug resistance from initially responsive tumors. Citation Format: Tengfei Yu, Ying Yan, Wei Du, Yuefei Yang, Tingting Tan, Xuqin Yang, Jiali Gu, Liang Hua, Xin K. Ye, Zhenyu Gu. Studying cancer drug resistance in patient derived xenograft tumor models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1212. doi:10.1158/1538-7445.AM2014-1212

Abstract 1846: Co-treatment with simvastatin and cetuximab in KRAS mutant LoVo cells decreases PTK activity effectively and increases STK activity to overcome the anti-EGFR resistance

Abstract Background: 40% of colorectal cancer patients have mutations in the KRAS gene, resulting in auto activation of KRAS and EGFR independent proliferation. Those patients are excluded from therapy with anti-EGFR antibodies. Activation of KRAS depends on its prenylation. The synthesis of prenyl groups is reduced by statins that are used as cholesterol lowering therapy by inhibiting HMG-CoA reductase. We hypothesize that KRAS mutated cell lines may become susceptible for cetuximab in the presence of simvastatin. To further elucidate the effect of these drugs on signal transduction we established kinase activity profiles using dynamic peptide microarrays. Methods: The cell lines LoVo, A431 and HCT116 were incubated for 24 hours with vehicle, simvastatin, cetuximab or combinations followed by lysis. Serine/threonine (STK) and tyrosine (PTK) kinase activity profiles were determined for all lysates in vitro using Pamgene's PTK and STK peptide microarrays comprising each 144 peptides derived from human protein phosphorylation sites. Results: In the KRAS mutant colorectal cancer cell line LoVo, the combination of simvastatin and cetuximab resulted in a synergistic growth reduction of 50%. No synergistic effects were observed in A431 (EGFR amplification) and only a small effect in HTC116 (KRAS mutant, PI3K mutant) For LoVo, treatment with cetuximab reduced the tyrosine kinase activity, whereas simvastatin had no significant effect. The combination treatment reduced tyrosine kinase activity even further. The treatment with either cetuximab or simvastatin increased activity of serine/threonine kinases. The combination resulted in an increase slightly less than for the single agent treatments. The kinomic results from the reference cell lines A431 and HTC116 were consistent with their proliferation responses as single agent or combination treatment. Conclusions: In LoVo cells, the synergistic decrease of growth by simvastatin and cetuximab could be explained by the block of EGFR and downstream PTK signalling by cetuximab. This inhibition, by the single agent is sufficient in A431, however, in case of LoVo cells, insufficient to reduce cell proliferation probably because of the constitutively active KRAS. By preventing KRAS prenylation by simvastatin, cell proliferation in LoVo is effectively reduced. The STK activity is increased in all treatment conditions and this could be due to stress mechanisms or in case of the combination therapy due to initiation of STK controlled apoptosis pathways leading to reduced cell proliferation. From these results, we conclude that in KRAS mutated cells, co-treatment with simvastatin and cetuximab decreases PTK activity effectively and increases STK activity which provides a molecular explanation for overcoming the anti-EGFR resistance. Citation Format: Lisanne Krens, Renee Pablo-Baak, Monique Mommersteeg, Maria Hilhorst, Rob Ruijtenbeek, Henk-Jan Guchelaar, Tahar van der Straaten. Co-treatment with simvastatin and cetuximab in KRAS mutant LoVo cells decreases PTK activity effectively and increases STK activity to overcome the anti-EGFR resistance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1846. doi:10.1158/1538-7445.AM2014-1846

Abstract 2626: Novel naphtoquinone PIC21 targets PI3K in triple negative breast cancer cell line

Abstract Background: Triple negative breast cancer (TNBC) is a heterogeneous subgroup (ER-, PR-, and HER2-) of aggressive breast cancer, which poor prognosis is partially due to chemoresistance to available drugs. We have synthesized and screened 43 novel naphtoquinone-derived drugs (patent-protected), rationally designed to act through multiple pathways to avoid tumor chemoresistance, in MDA-MB231 by cellular metabolic viability and IC50 calculation. Of these, the most promising drugs PIC20 and PIC21 showed significantly higher AE than cisplatin, doxorubicin and paclitaxel in the lineage. Methods: Based on the crystalline structure of protein deposited on Protein Data Bank ( 1E7U, PI3K), and PIC20 and PIC21 tridimensional structures, computational molecular dock studies were conducted to investigate the molecules PIC20 e PIC21 tridimensional conformation and bounding energy to PI3K (Autodock Vina software). In vitro PI3K inhibition by PIC21 in MDA-MB231 was assessed using the Flowcellect PI3K/Mapk Dual Pathway Activation and Cancer Marker Detection. For PI3K/Akt and MAPK signaling pathways, cells were pre treated with PIC21 (0,1mM, 2h) or Wortmannin (Wort) (0,1μM, 30 min). Cells were then treated with insulin (0,6μM, 5 min) for stimulation of PI3K/Akt and MAPK pathways and incubated with Anti-phospho-Akt1/PKBα Alexa Fluor® 488 Conjugated Antibody and Anti-phospho-Erk1/2- R- Phycoerythrin conjugated antibody. A FACSCanto II cytometer was used for the flow cytometric analysis. FSC and SSC were used to establish size gates and exclude cellular debris from the analysis. In each measurement, a minimum of 30000 events were analyzed. Data were acquired and analyzed using BD FACSDiva and DeNovo FCS software. Findings: PIC21 targeting of PI3K was confirmed by docking studies, which data demonstrated that the interaction energy (E) for PI3K and PIC21, and PI3K inhibitors, LY294002 and Wort, was: PIC20 (E=-8.9), PIC21(E=-8.2), LY294002 (E=-9.5), Wort (E=-8.8). Cell treatment with PIC21 and Wort decreased the pAkt+ cell population (control=23.02%, PIC21 treated=6.63%, Wort treated=4.20%), whereas the pERK+ cell population increased (control=0,58%, PIC21 treated=6,41%, Wort treated=10,14%. This is due to the pathways crosstalk, by which pAkt inhibits the MAPK/ERK pathway. Conclusions: Our data strongly points to PIC21 as a novel PI3K inhibitor. A high prevalence of PI3K mutation, leading to its constitutive activation, has been described in TNBC, favoring tumor cells growth, proliferation, metabolism, and survival. Therefore, PIC21 opens a new avenue to overcome TNBC dramatic epidemiological scenario, bringing hope to improve patients overall outcome and quality of life. Citation Format: Renata D. Daltoe, Klesia P. Madeira, Murilo F. Cerri, João F. Allochio Filho, Maicon Delarmelina, Marcella L. Porto, Silvana S. Meirelles, Silvana S. Meirelles, Ian V. Silva, Sandro J. Greco, Leticia B A Rangel. Novel naphtoquinone PIC21 targets PI3K in triple negative breast cancer cell line. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2626. doi:10.1158/1538-7445.AM2014-2626

PHASE II TRIAL OF THE PHOSPHATIDYINOSITOL-3 KINASE (PI3K) INHIBITOR BUPARLISIB (BKM120) IN RECURRENT GLIOBLASTOMA CONDUCTED BY THE IVY FOUNDATION EARLY PHASE CLINICAL TRIALS CONSORTIUM

BACKGROUND: The PI3K pathway is activated in most GBMs and represents a potential therapeutic target. Buparlisib is an oral, pan-Class I PI3K inhibitor that enters the brain at therapeutic concentrations and inhibits the growth of U87 and human glioma tumor sphere models. METHODS: The Ivy Consortium conducted a phase II study of buparlisib in recurrent GBM patients with activation of the PI3K pathway (mutation, homozygous deletion or loss of IHC of PTEN, PIK3CA or PIK3RI mutations, or detectable pAKT). Additional eligibility criteria included radiologic progression, 1st or 2nd relapse, >18 yrs, KPS >60, adequate bone marrow and organ function, no prior bevacizumab or enzyme-inducing antiepileptic drugs. Patients received buparlisib 100mg daily. The study consisted of 2 concurrent cohorts. In Cohort 1 (up to 15 patients) buparlisib was given for 8-12 days prior to surgery for recurrent disease. Patients underwent FDG PET, pharmacokinetic studies, and tumor was obtained for drug concentrations and pharmacodynamic effects. In Cohort 2, 50 patients with unresectable GBM received buparlisib with a primary endpoint of PFS6. RESULTS: 13 patients were enrolled into cohort 1, 50 into cohort 2. Treatment was fairly well-tolerated with no grade 4 toxicities. Grade 3 toxicities were asymptomatic lipase elevation (6), rash (4), hyperglycemia (3), fatigue (4), elevated ALT/AST (2), and 1 each with depression, anxiety, hypophosphatemia, thrombocytopenia and lymphopenia. Analysis of tumor specimens from Cohort 1 showed reduction of pAKT by IHC in 4/6 (67%) of evaluable patients. The combined cohorts showed minimal efficacy with median PFS of 1.8 months and median OS of 10.9 months. Best response was stable disease. Only 1 patient in each cohort achieved PFS6. Of the first 40 patients who underwent exome sequencing, there were 4 PIK3CA (10%), 2 PIK3R1 (5%) and 13 PTEN (33%) mutations. Patients with PTEN loss and or PI3K mutations paradoxically had a worse outcome. CONCLUSIONS: Buparlisib is well-tolerated in patients with recurrent GBM and achieves adequate tumor concentration to inhibit pAKTS473. However, single agent efficacy was minimal. Final correlation of tumor genotype with outcome will be presented. SECONDARY CATEGORY: n/a.

Activity of EGFR, mTOR and PI3K inhibitors in an isogenic breast cell line model

BackgroundThe epidermal growth factor receptor family is expressed in breast cancer, and agents targeting this pathway have single agent effects (e.g. traztuzumab). Development of resistance may be due to the presence of alternative pathways, particularly activation of the PI3K/Akt/MTOR pathway. We have therefore examined the effect of inhibitors of this pathway (ZSTK474 and sirolimus) in combination with the epidermal growth factor (EGFR) inhibitors erlotinib and gefitinib in breast MCF10a isogenic cell lines with EGFR, BRAF, AKT, and PI3K mutations.ResultsPI3K mutation conferred increased activity of EGFR inhibitors against MCF10a cells in comparison with the parental cell line and other mutations studied. Combination of EGFR inhibitors with either the PI3K inhibitor ZSTK474 or the MTOR inhibitor sirolimus showed increased activity.ConclusionsThese results are encouraging for the use of combinations targeting the PI3K and EGFR pathway simultaneously.

Targeting PI3K/mTOR overcomes resistance to HER2-targeted therapy independent of feedback activation of AKT.

Altered PI3K/mTOR signaling is implicated in the pathogenesis of a number of breast cancers, including those resistant to hormonal and HER2-targeted therapies. The activity of four classes of PI3K/mTOR inhibitory molecules, including a pan-PI3K inhibitor (NVP-BKM120), a p110α isoform-specific PI3K inhibitor (NVP-BYL719), an mTORC1-specific inhibitor (NVP-RAD001), and a dual PI3K/mTORC1/2 inhibitor (NVP-BEZ235), was evaluated both in vitro and in vivo against a panel of 48 human breast cell lines. Each agent showed significant antiproliferative activity in vitro, particularly in luminal estrogen receptor-positive and/or HER2(+) cell lines harboring PI3K mutations. In addition, monotherapy with each of the four inhibitors led to significant inhibition of in vivo growth in HER2(+) breast cancer models. The PI3K/mTOR pathway inhibitors were also effective in overcoming both de novo and acquired trastuzumab resistance in vitro and in vivo. Furthermore, combined targeting of HER2 and PI3K/mTOR leads to increased apoptosis in vitro and induction of tumor regression in trastuzumab-resistant xenograft models. Finally, as previously shown, targeting mTORC1 alone with RAD001 leads to consistent feedback activation of AKT both in vitro and in vivo, whereas the dual mTOR1-2/PI3K inhibitor BEZ235 eliminates this feedback loop. However, despite these important signaling differences, both molecules are equally effective in inhibiting tumor cell proliferation both in vitro and in vivo. These preclinical data support the findings of the BOLERO 3 trial that shows that targeting of the PI3K/mTOR pathway in combination with trastuzumab is beneficial in trastuzumab-resistant breast cancer.

Identification of driver gene alterations in Chinese female patients with squamous cell carcinomas of the lung.

e19087 Background: Smoking remains the leading risk factor of NSCLC. Activating mutations in EGFR gene have been reported more frequently in never smokers than smokers with NSCLC. Female pts with squamous cell carcinomas of the lung (SQCLC) differ from males in that most females are life-long never/light smokers. However, molecular abnormalities in female pts with SQCLC have not been well-characterized. Methods: We retrospectively screened 38 female and 40 male pts with SQCLC in China from 2009 to 2012 to determine the prevalence of alterations in EGFR, KRAS, ALK, PI3K, PTEN and FGFR1. Mutational analysis of EGFR, PIK3CA, KRAS and PTEN was performed using PCR-based DNA sequencing. FGFR1 amplification and ALKrearrangements were detected by FISH. A Cox regression model was used to assess the association between genomic mutation status and clinical features as well as OS. Results: 10.3% (8/78) pts were detected with EGFR mutation, 6.4% (5/78) with KRAS mutation, 7.7% (6/78) with PI3K mutation and 6.4% (5/78)...

A Prospective Pilot Study of Target-guided Personalized Chemotherapy with Intensity-modulated Radiotherapy in Patients With Early Rectal Cancer

To investigate the feasibility of personalizing chemotherapy in patients with rectal cancer. Patients with cT3 or cN1 and cM0 rectal cancer were eligible. A set of 6 molecular markers including KRAS, BRAF, and PI3K mutations and expression of topoisomerase-1 (Topo-1), ERCC-1, and thymidylate synthase (TS) using immunohistochemistry were performed in a tumor biopsy. All patients were treated with capecitabine 625 to 825 mg/m/12 h M-F in combination with either irinotecan or oxaliplatin based on Topo-1 and ERCC-1 expression plus either bevacizumab or cetuximab based on the mutation status. All patients received intensity-modulated radiation therapy. A surgery was performed 6 to 8 weeks after the treatment. Fifteen patients (94%) had T3 tumor and 10 (62%) N+ disease of 16 patients enrolled. In all patients, the full set of markers was analyzed within 10 days. Seven patients had K-ras mutation, and 4, 5, and 10 expressed Topo-1, ERRC-1 and TS, respectively. All patients had wild-type BRAF and PI3K tumors. The median time from obtaining informed consent to the treatment period was 18 days and all patients completed the chemoradiation treatment. Fifty percent achieved a complete pathologic response to treatment. Four patients (25%) developed grade 3 proctitis or diarrhea. There were no relevant surgical complications. Sixty-nine percent of the patients received adjuvant XELOX. The individualization of neoadjuvant chemotherapy in patients with rectal cancer is feasible and leads to a high rate of pathologic response.

Role of aberrant PI3K pathway activation in gallbladder tumorigenesis

The PI3K/AKT pathway governs a plethora of cellular processes, including cell growth, proliferation, and metabolism, in response to growth factors and cytokines. By acting as a unique lipid phosphatase converting phosphatidylinositol-3,4,5,- trisphosphate (PIP3) to phosphatidylinositol-4,5,-bisphosphate (PIP2), phosphatase and tensin homolog (PTEN) acts as the major cellular suppressor of PI3K signaling and AKT activation. Recently, PI3K mutations and loss/mutation of PTEN have been characterized in human gallbladder tumors; whether aberrant PTEN/PI3K pathway plays a causal role in gallbladder carcinogenesis, however, remains unknown. Herein we show that in mice, deregulation of PI3K/AKT signaling is sufficient to transform gallbladder epithelial cells and trigger fully penetrant, highly proliferative gallbladder tumors characterized by high levels of phospho-AKT. Histopathologically, these mouse tumors faithfully resemble human adenomatous gallbladder lesions. The identification of PI3K pathway deregulation as both an early event in the neoplastic transformation of the gallbladder epithelium and a main mechanism of tumor growth in Pten heterozygous and Pten mutant mouse models provides a new framework for studying in vivo the efficacy of target therapies directed against the PI3K pathway, as advanced metastatic tumors are often addicted to "trunkular" mutations.

VEGF Increases Paracellular Permeability in Brain Endothelial Cells via Upregulation of EphA2

Neurological disorders are associated with an increase in the permeability of human brain microvascular endothelial cells (HBMEC). Our previous findings have indicated that EphA2 could increase the permeability of HBMEC. Recent evidence has linked EphA2 and vascular endothelial growth factor (VEGF) to abnormalities in the vascular response. However, it is unclear whether EphA2 is involved in the VEGF-induced changes in the permeability of HBMEC. Here, changes in permeability were determined by measuring transendothelial electrical resistance (TEER) and the flux of FITC-dextran. We found that knockdown of EphA2 in HBMEC abolished the VEGF-induced reduction in TEER and increase in flux of fluorescent dextran. Moreover, VEGF-induced redistribution of ZO-1 and the recruitment of detergent-soluble occludin and claudin-5 were also prevented. Further results showed that VEGF increased EphA2 expression in a time- and dose-dependent manner, which was inhibited by a neutralizing antibody against VEGFR2 or SU1498. VEGF-induced EphA2 expression was suppressed in the brain endothelium following treatments with the PI3K inhibitor LY294002, Akt inhibitor or transfection with the dominant-negative PI3K mutants (Δp110). Similar results were obtained when ERK1/2 activation was inhibited by PD98059 or ERK1/2 siRNA transfection. Our data suggest that VEGF upregulates the expression of EphA2 in HBMEC through binding to VEGFR2 and subsequently activating the intracellular PI3K/Akt and ERK1/2 signaling pathways, which contribute to an increase in paracellular permeability. These data reveal a novel role for VEGF as a regulator of EphA2 expression in the brain endothelial cells and provide insights into the molecular mechanisms of VEGF-mediated changes in paracellular permeability.

Triple negative breast carcinoma EGFR amplification is not associated with EGFR, Kras or ALK mutations

Background:The amplification of epidermal growth factor receptor (EGFR) in triple negative breast carcinomas (TNBC) suggests its potential therapeutic application, as for HER-2, using standardised methods of measurement. In this regard, we aimed to compare several methods for evaluating EGFR amplification along with potential mutations for suitability in clinical practice.Methods:Tissue sections of 138 TNBCs were used (1) to compare EGFR amplification and expression by silver in situ hybridisation (SISH) to qPCR and immunohistochemistry (IHC) and (2) to search for EGFR mutations, along with Kras, PI3K, Braf and HER-2 mutations and echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) translocation.Results:(1) Amplification of EGFR was observed in well-characterised TNBCs (up to 92%); (2) qPCR correlated with SISH with 94% specificity and 75.6% sensitivity; (3) IHC correlated with SISH with 97% sensitivity and 78% specificity; (4) no EGFR, Kras mutations or EML4-ALK translocations were found, but PI3K and Braf mutations were observed in 26% of cases; and (5) small, acentric circular extrachromosomal DNA similar to ‘double minutes' in glioblastomas was observed in 18% of SISH sections.Conclusions:SISH and IHC are methods that are suitable in clinical practice to screen for EGFR amplification and overexpression, which are frequently observed in TNBC. Patients with TNBC are potential candidates for EGFR-targeted therapy combined with PI3K and Braf inhibitors.

Evaluation of reverse phase protein array (RPPA)-based pathway-activation profiling in 84 non-small cell lung cancer (NSCLC) cell lines as platform for cancer proteomics and biomarker discovery

The reverse phase protein array (RPPA) approach was employed for a quantitative analysis of 71 cancer-relevant proteins and phosphoproteins in 84 non-small cell lung cancer (NSCLC) cell lines and by monitoring the activation state of selected receptor tyrosine kinases, PI3K/AKT and MEK/ERK1/2 signaling, cell cycle control, apoptosis, and DNA damage. Additional information on NSCLC cell lines such as that of transcriptomic data, genomic aberrations, and drug sensitivity was analyzed in the context of proteomic data using supervised and non-supervised approaches for data analysis. First, the unsupervised analysis of proteomic data indicated that proteins clustering closely together reflect well-known signaling modules, e.g. PI3K/AKT- and RAS/RAF/ERK-signaling, cell cycle regulation, and apoptosis. However, mutations of EGFR, ERBB2, RAF, RAS, TP53, and PI3K were found dispersed across different signaling pathway clusters. Merely cell lines with an amplification of EGFR and/or ERBB2 clustered closely together on the proteomic, but not on the transcriptomic level. Secondly, supervised data analysis revealed that sensitivity towards anti-EGFR drugs generally correlated better with high level EGFR phosphorylation than with EGFR abundance itself. High level phosphorylation of RB and high abundance of AURKA were identified as candidates that can potentially predict sensitivity towards the aurora kinase inhibitor VX680. Examples shown demonstrate that the RPPA approach presents a useful platform for targeted proteomics with high potential for biomarker discovery. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Abstract P1-08-34: Is it possible to predict the efficacy of a combination of cetuximab plus docetaxel in patients with operable, triple negative breast cancer (TNBC)? Final biomarker results from a phase II neoadjuvant trial

Abstract Background: TNBC is a heterogenous group of tumors for some of which the Epithelial Growth Factor Receptor pathway (EGFR) may play an important role. We evaluated the efficacy and toxicity of an anti-EGFR antibody (cetuximab) combined with docetaxel, which were given to the TNBC patients (pts) in the neoadjuvant setting. A biomarker analysis accompanied this trial, aiming to identify predictors of response. Methods: 35 patients with stage II-IIIA TN breast disease were prospectively included in this multicentre pilot study. Systemic therapy (ST) consisted of 6 cycles of docetaxel (100 mg/m2) each 3 weeks, in combination with weekly cetuximab (first dose 400mg/m2 then 250 mg/m2/week) for 6 cycles. All patients underwent surgery at completion of ST. Patient characteristics : mean age 48 [28-67]; TNM: T1: 3%, T2: 73%, T3: 24%; N0: 61%, N1-N2: 39%; mean tumor size 40 mm [15-100]; SBR: grade III: 73%, grade II: 27%. The median number of cycles was for docetaxel 6 [1-6] and for cetuximab 15 [1-18]. Pathological complete response (pCR) rate was 24% according to the Chevallier and Sataloff classifications; 28% if we consider breast pCR only. Overall clinical response rate was 57% (22% CR). Conservative surgery was performed in 75% of cases. The main side effect was skin toxicity: grade II: 39%, grade III: 36%, grade IV: 3%. Other side effects were: neutropenia grade IV: 12.7%, febrile neutropenia: 1.3%, hand-foot syndrome grade III: 3%, grade II: 3%, ungueal toxicity grade III: 3%, grade II: 33%. Paraffin-embedded and frozen samples were systematically collected before and after ST for biomarker studies. Germinal BRCA1 mutations and EGFR, KRAS, BRAF and PI3KCA somatic mutations were analyzed by NGS. EGFR, MET, cytokeratins 5/6 and 8/18, PTEN, P-cadherin, ALDH1, Ki67, p53 and the number of FOXP3+ or CD8+ tumor-infiltrating lymphocytes (TIL) were evaluated by immunohistochemistry. Results: The biomarker analysis was interpretable on the samples from 21 pts (3 pCR and 18 non-pCR). We applied the ROC curve to identify the best cut-off value for Ki67, EGFR, MET, cytokeratin 5/6 and 8/18, p53, ALDH1, PTEN, P-cadherin and the FOXP3+ or CD8+ TIL counts. None of these biomarkers was predictive of pCR except for the CD8+/FOXP3+ TIL count ratio. pCR rate was higher in the pts with the ratio equal or higher than 2.75 than in the others (43% versus 0%, p = 0.047). BRCA1 mutations were detected in 16% of pts. PI3K and EGFR somatic mutations were observed in 1 and 3 patients, respectively. The presence of the mutations was not predictive of pCR. Conclusion: Similarly to the previously reported trial by our group (SABCS 2012, abstract 1081), the immune component of the tumor microenvironment plays a very important role in the TNBC response to cytotoxic therapy. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-34.

IN6 ADVANCES IN CYTOTOXIC AND OTHER TARGETED THERAPY OUT OF HER2, ER AND TRIPLE NEGATIVE METASTATIC BREAST CANCERS

transduction pathways. Particularly, in the past year, encouraging results have emerged from studies testing mammalian target of rapamycin (mTOR) inhibitors, such as the BOLERO-2 that showed an increase in the median progression-free survival from 4.1 to 10.6 months with the addition of everolimus to exemestane (central assessment), in the interim analysis (hazard ratio for progression/ death 0.36, p<0.001). Several other clinical phase II and phase III trials are underway combining anti-mTOR agents, such has BELLE-3 (BKM120 + fulvestrant), PrE0102 (fulvestrant ± everolimus) or TAMRAD (tamoxifen ± everolimus); insulin-like growth factor receptor-1 (IGFR1) inhibitors (AMG 479 + exemestane or fulvestrant); histone deacetylase (HDAC) inhibitors (vorinostat + tamoxifen) and phosphatidylinositol3-kinase/Akt (PI3K/AKT) inhibitors. So far, the most promising results come from the combination of everolimus and endocrine agents, as has been shown in the TAMRAD and BOLERO-2 studies. Because these new therapies carry a cost in terms of side effects and finances, it will be important to identify biomarkers of enhanced benefit: preliminary results in this field will be presented. Besides addressing the identification of the best partner for combination with an endocrine agent, trials examining the intermittent administration of endocrine therapy, as in prostate cancer, could also be appealing, in an attempt to obviate the menopausal symptoms experienced by patients, which are known to compromise treatment adherence, and, as a result, can “fuel” tumour resistance. Finding new targets is also sought. The androgen receptor (AR) as a target in breast cancer seems to have regained interest recently and research is underway to clarify its role both as a prognostic and predictive biomarker. The cross-talk between the AR and HER2 pathways and the relationship between AR levels and mutations in PI3K are being examined and constitute a possible new hope in the treatment of advanced breast cancer.

Abstract B231: Jab1/Csn5 a new player driving the resistance to Her2-targeted therapies for breast cancer.

Abstract Her2 a key member in the epidermal growth factor receptor (EGFR) family, is one of the most dominant oncogenes in breast cancer. It is overexpressed in approximately 25%-30% of human breast cancers, which confers a more aggressive tumor phenotype and is associated with poor prognosis. The most effective FDA-approved therapy targeting Her2 is the monoclonal antibody trastuzumab (Ttzm; Herceptin). Ttzm inhibits Her2 activation and blocks downregulation of PI3K/Akt activities, which ultimately leads to increased expression of the cyclin-dependent kinase inhibitor p27, cell cycle arrest, and/or apoptosis. However, about 75% of Her2-positive breast tumors are or become resistant to Ttzm and experience relapse or disease progression. This suggests that tumors acquire or possess an intrinsic mechanism of resistance that prevents from Her2 inhibition. Therefore, it is important for the clinic to identify novel pathway to overcome the resistance. Clinicians cannot predict which patients with Her2-positive breast cancer will benefit from this treatment. Despite extensive studies, the mechanisms and genes responsible for resistance to trastuzumab (Ttzm) have not been entirely identified. Thus, novel strategies for treating Her2-positive disease are urgently needed. Recent studies have proposed that resistance to Ttzm is related to IGF-1R overexpression, rapid p27 degradation, PTEN loss, and PI3K mutations, but a clear target for modifying its resistance has yet to be identified. The cytostatic effect of Ttzm correlates with downregulation of Akt activity, which ultimately leads to increased expression of the cyclin-dependent kinase inhibitor p27, cell cycle arrest and/or apoptosis. c-Jun activation domain-binding protein 1 (Jab1/Csn5), a novel candidate oncogene that we identified, contributes to the progression of breast carcinoma and is correlated with poor prognosis. Jab1/Csn5 expression is low or absent in normal adults breast tissues, but over-expressed in 50% of primary breast tumor and 90% of metastatic breast cancer and other tumor types (ovarian cancer, pancreatic, non-small-cell lung carcinoma, and non-Hodgkin's lymphomas). Jab1/Csn5 negatively regulates p27 tumor suppressor gene, mediates p27 nuclear-to-cytoplasmic export and degradation. Jab1 levels are inversely associated with p27 expression in vitro and in vivo, which means that its up-regulation may contribute to trastuzumab (Ttzm) resistance by promoting p27 degradation. This study was conducted to investigate the role of Jab1 in modulating trastuzumab (Ttzm) resistance. We hypothesize that overexpression of Jab1 plays a crucial role in resistance to Ttzm through negative regulation of the cell-cycle inhibitor p27. Using molecular approaches and pre-clinical studies we identified the pathway leading to resistance the Ttzm. In this study, we will test a novel paradigm that inhibition of Jab1 expression renders Ttzm-resistant cells sensitive to Ttzm by stabilizing nuclear p27 expression levels. Finally Jab1 could be used as a predictive marker of tumor response to Ttzm, which could assist clinicians in selecting the best treatment modalities for patients with breast cancer Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B231. Citation Format: Thuy T. Vu, Terry J. Shackleford, Qingxiu Zhang, Francisco J. Esteva, Elias Drakos, Ling Tian, Timothy Kute, Aysegul A. Sahin, George Z. Rassidakis, Francois X. Claret. Jab1/Csn5 a new player driving the resistance to Her2-targeted therapies for breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B231.

Clinical and pathologic characteristics of patients with PI3K-mutant breast cancers.

8 Background: Mutations in PIK3CA are the most common somatic alterations in breast cancer and represent a potentially useful therapeutic target. As more PI3K pathway inhibitors enter the clinical arena, it is important to understand the characteristics of patients harboring mutations. This study seeks to identify the clinico/pathological characteristics of PI3K mutant breast cancers in patients evaluated at Vanderbilt University Medical Center. Methods: Molecular profiling (SNaPShot) was used to detect mutations in three genes in the PI3K pathway (PIK3CA, PTEN, AKT1). Electronic medical records of breast cancer patients whose tumors underwent testing from June 2010 to January 2013 were reviewed. PI3K mutation rates, histological tumor grade, receptor status (ER/PR/HER2), and recurrence-free survival were tabulated. Results: Three hundred evaluable tests were identified, with PI3K mutations detected in 83/300 (28%). Patients with PI3K mutations were more likely to be ER/PR positive (73% vs. 48%; p&lt;0.001) and less likely to be HER2 positive (6.0% vs. 20.7%, p=0.0022). Only 6/83 patients (7.2%) with triple negative cancers harbored PI3K mutations. 32% of patients with PI3K mutations participated in clinical trials, versus 25% without. Conclusions: Tumors with PI3K mutations were more likely to be ER/PR positive, of intermediate grade, and associated with longer recurrence-free survival. Patients with PI3K mutations were more likely to participate in clinical trials. These data and the potential eligibility of patients harboring mutations for clinical trials support the prognostic and clinical utility of SNaPShot testing for all breast cancer patients at a tertiary care center. [Table: see text]

Analysis of PTEN, BRAF and PI3K status for determination of benefit from cetuximab therapy in metastatic colorectal cancer patients refractory to chemotherapy with wild-type KRAS

We investigated predictive values of BRAF, PI3K and PTEN in cetuximab responses in KRAS wild-type (+) chemotherapy refractory, metastatic colorectal cancer (CRC) patients. Primary tumour tissues of 41 KRAS wild-type mCRC patients receiving cetuximab-based chemotherapy were investigated for PI3K, PTEN, KRAS and BRAF mutations. Progression-free survival (PFS) and overall survival (OS) periods were calculated with Kaplan-Meier method and the Cox proportional hazards model was used. PTEN and PI3K expressions were 63 and 42 %, respectively. BRAF mutation was observed as 9.8 % among patients. Tumours with BRAF mutation had statistically lower response rates (RR) for cetuximab-based treatment than tumours with BRAF wild type (0 vs. 58 %, p = 0.02). PTEN expressing tumours had statistically higher RR for cetuximab-based treatment than tumours with PTEN loss (42 vs. 12 %, p = 0.04). PI3K expression had worse significant effect on cetuximab RR than PI3K non-expressed tumours (15 vs. 44 %, p = 0.023). Median PFS was significantly longer in patients with PTEN expression (14 months) than in patients with PTEN loss (5 months) (HR, 0.4; p = 0.028). Median PFS was significantly longer in patients with PI3K non-expression (15.2 months) than in patients with PI3K expression (4.1 months) (HR, 0.31; p = 0.001). Significant difference in PFS and OS between patients with BRAF mutated and BRAF wild-type tumours was not detected. However, patients with PTEN expression had significantly longer OS (15.1 months) than patients with PTEN loss tumour (9.9 months) (HR, 0.34; p = 0.008). Patients without PI3K expression had significantly longer OS (18.2 months) than patients with PI3K expression (10.1 months) (HR, 0.27; p = 0.001). Multivariate analyses revealed that PTEN expression (HR, 0.48; p = 0.02) and absence of PI3K expression (HR, 0.2; p = 0.001) were independent prognostic factors for increased PFS. Similarly, PTEN overexpression (HR, 0.62; p = 0.03) and absence of PI3K expression (HR, 0.27; p = 0.005) were independent prognostic factors for increased OS. In PTEN loss, PI3K expression may be used as biomarkers to further select KRAS wild-type patients undergoing anti-epidermal growth factor receptor treatment.

Dual PI3K/mTOR Inhibitor NVP-BEZ235 Sensitizes Docetaxel in Castration Resistant Prostate Cancer

Effective therapeutic strategies that can achieve long-term improvement in patients with castration resistant prostate cancer are urgently needed. We recently reported that the activated PI3K/Akt/mTOR signaling pathway induced by docetaxel explains resistance to docetaxel in castration resistant prostate cancer. In this study we explored the efficacy of NVP-BEZ235, a dual PI3K and mTORC1/2 inhibitor, for docetaxel resistant castration resistant prostate cancer. We used the 2 human castration resistant prostate cancer cell lines C4-2 and C4-2AT6. At our laboratory C4-2AT6 cells were established from C4-2 under androgen ablated treatment for 6 months. We investigated the efficacy of NVP-BEZ235 monotherapy and NVP-BEZ235 combined with docetaxel in vitro and in vivo. Increased phosphorylated Akt in C4-2AT6 cells was significantly inhibited by NVP-BEZ235 in a dose and time dependent manner. WST cell proliferation assay results in C4-2AT6 cells revealed that combined administration of NVP-BEZ235 and docetaxel had significant, synergistically greater cytotoxicity than NVP-BEZ235 or docetaxel monotherapy. Combined NVP-BEZ235 (40 mg/kg) and docetaxel (4 mg/kg) in vivo in a castrated mouse xenograft model inhibited C4-2AT6 tumor growth to a greater degree than in the monotherapy groups. Also, NVP-BEZ235 showed significant efficacy with docetaxel at a low concentration in vivo, suggesting that NVP-BEZ235 effectively decreased resistance to docetaxel. Results suggest that inhibition of the PI3K/Akt/mTOR signaling pathway by NVP-BEZ235 can overcome docetaxel resistance in human castration resistant prostate cancer. Our findings provide a molecular basis for the clinical use of combined administration of NVP-BEZ235 and docetaxel in patients with castration resistant prostate cancer.

β5 Integrin Up-Regulation in Brain-Derived Neurotrophic Factor Promotes Cell Motility in Human Chondrosarcoma

Chondrosarcoma is a primary malignant bone cancer, with a potent capacity to invade locally and cause distant metastasis; it has a poor prognosis and shows a predilection for metastasis to the lungs. Brain derived neurotrophic factor (BDNF) is a small-molecule protein from the neurotrophin family of growth factors that is associated with the disease status and outcomes of cancers. However, the effect of BDNF on migration activity in human chondrosarcoma cells is mostly unknown. Here, we found that human chondrosarcoma tissues showed significant expression of BDNF, which was higher than that in normal cartilage and primary chondrocytes. We also found that BDNF increased the migration and expression of β5 integrin in human chondrosarcoma cells. In addition, knockdown of BDNF expression markedly inhibited migratory activity. BDNF-mediated migration and β5 integrin up-regulation were attenuated by antibody, inhibitor, or siRNA against the TrkB receptor. Pretreatment of chondrosarcoma cells with PI3K, Akt, and NF-κB inhibitors or mutants also abolished BDNF-promoted migration and integrin expression. The PI3K, Akt, and NF-κB signaling pathway was activated after BDNF treatment. Taken together, our results indicate that BDNF enhances the migration of chondrosarcoma by increasing β5 integrin expression through a signal transduction pathway that involves the TrkB receptor, PI3K, Akt, and NF-κB. BDNF thus represents a promising new target for treating chondrosarcoma metastasis.

Molecular analysis in breast cancer subtypes and correlation with pathologic complete response (pCR) to neoadjuvant chemotherapy.

e22119 Background: Although it is know that pCR following neoadjuvant chemotherapy is more frequent in some subtypes of breast cancer such as Triple Negative (TN) or erb2 tumors, the predictive role of gene expression and mutation status is not well defined in this setting. Methods: We analyzed samples from 41 patients (p) prospectively treated with neoadjuvant chemotherapy (sequential AC followed by weekly TXL, or inverse sequence, plus trastuzumab for erb2 positive p). Pathologic response (PR) was classified according to Miller-Payne and RCB criteria. Radiologic evaluation was performed by ultrasonography, dynamic MR and PET-TAC after each chemotherapy sequence. We performed expression analysis of AXL, BRCA1, RAP80, BIM, EZH2, ROR1, FGFR1, PTPN12, YAP, GAS6, beta-TRCP, HIF1 alpha and ZNF217 by RT-PCR, and mutational status of p53 and PI3K genes in pretreatment biopsies. Statistical analysis was performed using Mann-Whitney U and Pearson’s chi-squared tests. Results: pCR was detected in 5 p (3TN, 2 erb2) of 25 p (9 luminal A, 5 luminal B, 6 erb2 and 5 TN) evaluated for PR at time of submitting this abstract. TN tumors had lower levels of RAP80 (p=.0013), PTPN12 (p=.003), beta TRCP (p=.001), ZNF217 (p=.014) and YAP (p=.097). Luminal B tumors had low levels of YAP and the highest levels of FGFR1 (p=.09) and ZNF217 (p=.014). Luminal A tumors had high levels of beta-TRCP (p=.003). We found no differences in BRCA1, AXL, BIM, EZH2, ROR1, GAS6 and HIF1 levels by breast cancer subtype. P with low levels of FGFR1 (p=.087), HIF1alpha (p=.07) or EZH2 (p=.005) had higher probability of pCR. No pCR was observed in p with higher levels of AXL, EZH2, RAP80, GAS6, beta TRCP, HIF alpha. Four p had p53 mutations (1 luminal B, 1 erb2 and 2 TN) and 4 p had PI3K mutations (2 luminal A, 1 erb2, 1 luminal B). There was no correlation between p53 status and PR. P with PI3K mutations did not achieve pCR vs 46% of p with wild type PI3K (p=.23). Conclusions: Gene expression profile varies by breast cancer subtype. Chemosensitivity could be higher in tumors with lower levels of FGFR1, HIF1alpha or EZH2. Further results will be presented.