[Show abstract][Hide abstract] ABSTRACT: Purpose:
To identify new therapeutic targets in non-small cell lung cancer (NSCLC), we systematically evaluated two cancer cell line databases with sensitivity data for a broad range of drugs. We identified polo-like kinase 1 (PLK1) as the most promising target for further investigation based on a subset of sensitive cell lines and inhibitors that were in advanced clinical development.
To identify potential biomarkers of response and mechanisms of PLK1 inhibitor-induced apoptosis, we performed an integrated analysis of gene and protein expression, gene mutation, and drug sensitivity using three PLK1 inhibitors (volasertib, BI2536, GSK461364) in a large panel of NSCLC cell lines.
NSCLC cell lines have different sensitivities to PLK1 inhibition, with a minority demonstrating sensitivity to all three inhibitors. PLK1 inhibition led to G2/M arrest, but only sensitive cell lines underwent substantial apoptosis following PLK1 inhibition. NSCLC lines with a high epithelial-mesenchymal transition gene signature score (i.e., mesenchymal lines) were more sensitive to PLK1 inhibitors than epithelial lines (p<0.02). Likewise, proteomic profiling demonstrated that E-cadherin expression was higher in the resistant cell lines (p<0.01). Induction of an epithelial phenotype using miR-200 expression increased resistance to PLK1 inhibition. KRAS mutation and alterations in tight-junction, ErbB, and Rho signaling pathways also correlated with drug response.
We demonstrate that epithelial-mesenchymal transition leads to PLK1 inhibitor sensitivity in the first large-scale, integrated analysis of PLK1 inhibitor sensitivity. Our findings have important clinical implications for mesenchymal NSCLC, a significant subset of this disease associated with resistance to currently approved targeted therapies.
Full-text · Article · Nov 2015 · Clinical Cancer Research
[Show abstract][Hide abstract] ABSTRACT: Treatments for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) have limited efficacy. One potential therapeutic target for HNSCC is the RAS/RAF/MEK/ERK cascade, which is one of the major signaling pathways for HNSCC cell survival. In HNSCC, RAS can be activated either by HRAS mutation or by upstream signaling. The ABL inhibitor nilotinib acts as a weak RAF inhibitor that induces RAF dimerization and subsequent activation of MEK/ERK in other cancer cell lines with activated RAS, leading to an unexpected dependence on MEK/ERK for cell survival. We hypothesized that nilotinib and the MEK inhibitor MEK162 would be synergistic in HNSCC cell lines owing to the frequent activation of RAS. We treated HNSCC cell lines with nilotinib and performed immunoblotting and cell-viability experiments. We used an orthotopic mouse model to assess synergistic effects in vivo. Nilotinib induced significant BRAF-CRAF heterodimerization and ERK activation irrespective of RAS mutation status. In cell-viability assays, nilotinib synergized with MEK162. MEK162 alone induced G1 arrest that was minimally enhanced by nilotinib. In the mouse model, treatment with MEK162 alone or combined with nilotinib led to tumor growth inhibition. In HNSCC, nilotinib-induced RAF dimerization is independent of RAS mutation status, but this dimerization does not lead to MEK dependence for cell survival in all HNSCC cell lines. MEK inhibition alone leads to decreased proliferation both in vitro and in vivo. Although nilotinib has some synergistic effects with MEK162, other agents may be more effective against HNSCC when combined with MEK162.
No preview · Article · Jun 2015 · Anti-cancer drugs
[Show abstract][Hide abstract] ABSTRACT: The PI3K/AKT/mTOR pathway is frequently activated in head and neck squamous cell carcinoma (HNSCC), but pathway inhibition has variable efficacy. Identification of predictive biomarkers and mechanisms of resistance would allow selection of patients most likely to respond and novel therapeutic combinations. The purpose of this study was to extend recent discoveries regarding the PI3K/AKT/mTOR pathway in HNSCC by more broadly examining potential biomarkers of response, by examining pathway inhibitors with a diverse range of targets, and by defining mechanisms of resistance and potential combination therapies. We used reverse-phase protein arrays (RPPA) to simultaneously evaluate expression of 195 proteins; single-nucleotide polymorphism array to estimate gene copy number; and mass array to identify mutations. We examined altered signaling at baseline and after pathway inhibition. Likewise, we examined the activation of the PI3K/AKT/mTOR pathway in HNSCC tumors by RPPA. Cell lines with PIK3CA mutations were sensitive to pathway inhibitors, whereas amplification status did not predict sensitivity. While we identified a set of individual candidate biomarkers of response to pathway inhibitors, proteomic pathway scores did not correlate with amplification or mutation and did not predict response. Several receptor tyrosine kinases, including EGFR and ERK, were activated following PI3K inhibition in resistant cells; dual pathway inhibition of PI3K and EGFR or MEK demonstrated synergy. Combined MEK and PI3K inhibition was markedly synergistic in HRAS-mutant cell lines. Our findings indicate that clinical trials of single-agent PI3K/AKT/mTOR pathway inhibitors in selected populations and of PI3K-EGFR or PI3K-MEK inhibitor combinations are warranted; we plan to conduct such trials.
Full-text · Article · Sep 2014 · Molecular Cancer Therapeutics
[Show abstract][Hide abstract] ABSTRACT: Importance
Targeting oncogenic drivers (genomic alterations critical to cancer development and maintenance) has transformed the care of patients with lung adenocarcinomas. The Lung Cancer Mutation Consortium was formed to perform multiplexed assays testing adenocarcinomas of the lung for drivers in 10 genes to enable clinicians to select targeted treatments and enroll patients into clinical trials.Objectives
To determine the frequency of oncogenic drivers in patients with lung adenocarcinomas and to use the data to select treatments targeting the identified driver(s) and measure survival.Design, Setting, and Participants
From 2009 through 2012, 14 sites in the United States enrolled patients with metastatic lung adenocarcinomas and a performance status of 0 through 2 and tested their tumors for 10 drivers. Information was collected on patients, therapies, and survival.Interventions
Tumors were tested for 10 oncogenic drivers, and results were used to select matched targeted therapies.Main Outcomes and Measures
Determination of the frequency of oncogenic drivers, the proportion of patients treated with genotype-directed therapy, and survival.Results
From 2009 through 2012, tumors from 1007 patients were tested for at least 1 gene and 733 for 10 genes (patients with full genotyping). An oncogenic driver was found in 466 of 733 patients (64%). Among these 733 tumors, 182 tumors (25%) had the KRAS driver; sensitizing EGFR, 122 (17%); ALK rearrangements, 57 (8%); other EGFR, 29 (4%); 2 or more genes, 24 (3%); ERBB2 (formerly HER2), 19 (3%); BRAF, 16 (2%); PIK3CA, 6 (<1%); MET amplification, 5 (<1%); NRAS, 5 (<1%); MEK1, 1 (<1%); AKT1, 0. Results were used to select a targeted therapy or trial in 275 of 1007 patients (28%). The median survival was 3.5 years (interquartile range [IQR], 1.96-7.70) for the 260 patients with an oncogenic driver and genotype-directed therapy compared with 2.4 years (IQR, 0.88-6.20) for the 318 patients with any oncogenic driver(s) who did not receive genotype-directed therapy (propensity score–adjusted hazard ratio, 0.69 [95% CI, 0.53-0.9], P = .006).Conclusions and Relevance
Actionable drivers were detected in 64% of lung adenocarcinomas. Multiplexed testing aided physicians in selecting therapies. Although individuals with drivers receiving a matched targeted agent lived longer, randomized trials are required to determine if targeting therapy based on oncogenic drivers improves survival.Trial Registration
clinicaltrials.gov Identifier: NCT01014286.
Full-text · Article · May 2014 · JAMA The Journal of the American Medical Association
[Show abstract][Hide abstract] ABSTRACT: Despite decades of research, the role of induction chemotherapy (ICT) in the treatment of locally advanced head and neck squamous cell carcinoma remains controversial. When nonsurgical approaches are preferred, chemoradiation (CRT) is the standard of care. However, ICT continues to be investigated, as it can cytoreduce tumors, improve radiotherapy feasibility and tolerability, select patients for organ preservation with radiation, and decrease the risk of distant metastasis.
Herein, we review the recent randomized trials that investigated the role of taxanes in ICT, compared with surgery or CRT alone. A metaanalysis of older trials comparing taxane-containing ICT to cisplatin and 5-fluorouracil is discussed. In addition, long-term results from Radiation Therapy Oncology Group 91-11, a three-arm trial of larynx preservation approaches, are discussed, as well as a recent trial of sequential CRT for larynx preservation. As in previous randomized trials, no survival benefit for ICT was demonstrated. However, two studies showed a reduced risk of distant metastasis in advanced nodal stage patients. As regards larynx preservation, ICT followed by radiation alone in responders to chemotherapy remains an effective option.
ICT is still controversial and in general, should remain investigational. An exception may be its use in a larynx preservation approach, albeit with a lower crude larynx preservation rate compared with CRT. The results of recent trials provide rationale and support hypothesis generation for future research, which should focus on subsets of patients most likely to benefit, for example, high nodal stage. It will be critical to study human papillomavirus (HPV)-associated oropharynx cancer separately or, at least, stratify by HPV status given its influence on prognosis and attendant implications for statistical design.
No preview · Article · Mar 2014 · Current opinion in oncology
[Show abstract][Hide abstract] ABSTRACT: Several phase II/III trials of anti-insulin-like growth factor 1 receptor (IGF-1R) monoclonal antibodies (mAbs) have shown limited efficacy. The mechanisms of resistance to IGF-1R mAb-based therapies and clinically applicable strategies for overcoming drug resistance are still undefined.
IGF-1R mAb cixutumumab efficacy, alone or in combination with Src inhibitors, was evaluated in 10 human head and neck squamous cell carcinoma (HNSCC) and six non-small cell lung cancer (NSCLC) cell lines in vitro in two- or three-dimensional culture systems and in vivo in cell line- or patient-derived xenograft tumors in athymic nude mice (n = 6-9 per group). Cixutumumab-induced changes in cell signaling and IGF-1 binding to integrin β3 were determined by Western or ligand blotting, immunoprecipitation, immunofluorescence, and cell adhesion analyses and enzyme-linked immunosorbent assay. Data were analyzed by the two-sided Student t test or one-way analysis of variance.
Integrin β3-Src signaling cascade was activated by IGF-1 in HNSCC and NSCLC cells, when IGF-1 binding to IGF-1R was hampered by cixutumumab, resulting in Akt activation and cixutumumab resistance. Targeting integrin β3 or Src enhanced antitumor activity of cixutumumab in multiple cixutumumab-resistant cell lines and patient-derived tumors in vitro and in vivo. Mean tumor volume of mice cotreated with cixutumumab and integrin β3 siRNA was 133.7mm(3) (95% confidence interval [CI] = 57.6 to 209.8mm(3)) compared with those treated with cixutumumab (1472.5mm(3); 95% CI = 1150.7 to 1794.3mm(3); P < .001) or integrin β3 siRNA (903.2mm(3); 95% CI = 636.1 to 1170.3mm(3); P < .001) alone.
Increased Src activation through integrin ανβ3 confers considerable resistance against anti-IGF-1R mAb-based therapies in HNSCC and NSCLC cells. Dual targeting of the IGF-1R pathway and collateral integrin β3-Src signaling module may override this resistance.
Full-text · Article · Oct 2013 · Journal of the National Cancer Institute
[Show abstract][Hide abstract] ABSTRACT: Background:
We performed this study to define the incidence of radiographic retropharyngeal lymph node (RPLN) involvement in oropharyngeal cancer (OPC) and its impact on clinical outcomes, neither of which has been well established to date.
Our departmental database was queried for patients irradiated for OPC between 2001 and 2007. Analyzable patients were those with imaging data available for review to determine radiographic RPLN status. Demographic, clinical, and outcome data were retrieved and analyzed.
The cohort consisted of 981 patients. The median follow-up was 69 months. The base of the tongue (47%) and the tonsil (46%) were the most common primary sites. The majority of patients had stage T1 to T2 primary tumors (64%), and 94% had stage 3 to 4B disease. Intensity-modulated radiation therapy was used in 77% of patients, and systemic therapy was administered in 58% of patients. The incidence of radiographic RPLN involvement was 10% and was highest for the pharyngeal wall (23%) and lowest for the base of the tongue (6%). RPLN adenopathy correlated with several patient and tumor factors. RPLN involvement was associated with poorer 5-year outcomes on univariate analysis (P<.001 for all) for local control (79% vs 92%), nodal control (80% vs 93%), recurrence-free survival (51% vs 81%), distant metastases-free survival (66% vs 89%), and overall survival (52% vs 82%) and maintained significance on multivariate analysis for local control (P = .023), recurrence-free survival (P = .001), distant metastases-free survival (P = .003), and overall survival (P = .001).
In this cohort of nearly 1000 patients investigating [corrected] radiographic RPLN adenopathy in OPC, RPLN involvement was observed in 10% of patients and portends [corrected] a negative influence on disease recurrence, distant relapse, and survival. In this cohort of nearly 1000 patients investigating radiographic RPLN adenopathy in OPC, RPLN involvement was observed in 10% of patients and portends a negative influence on disease recurrence, distant relapse, and survival.