Crizotinib inhibition of ROS1-positive tumours in advanced non-small-cell lung cancer: a Canadian perspective

The ros1 kinase is an oncogenic driver in non-small-cell lung cancer (nsclc). Fusion events involving the ROS1 gene are found in 1%-2% of nsclc patients and lead to deregulation of a tyrosine kinase-mediated multi-use intracellular signalling pathway, which then promotes the growth, proliferation, and progression of tumour cells. ROS1 fusion is a distinct molecular subtype of nsclc, found independently of other recognized driver mutations, and it is predominantly identified in younger patients (<50 years of age), women, never-smokers, and patients with adenocarcinoma histology. Targeted inhibition of the aberrant ros1 kinase with crizotinib is associated with increased progression-free survival (pfs) and improved quality-of-life measures. As the sole approved treatment for ROS1-rearranged nsclc, crizotinib has been demonstrated, through a variety of clinical trials and retrospective analyses, to be a safe, effective, well-tolerated, and appropriate treatment for patients having the ROS1 rearrangement. Canadian physicians endorse current guidelines which recommend that all patients with nonsquamous advanced nsclc, regardless of clinical characteristics, be tested for ROS1 rearrangement. Future integration of multigene testing panels into the standard of care could allow for efficient and cost-effective comprehensive testing of all patients with advanced nsclc. If a ROS1 rearrangement is found, treatment with crizotinib, preferably in the first-line setting, constitutes the standard of care, with other treatment options being investigated, as appropriate, should resistance to crizotinib develop.

Improving molecular testing and personalized medicine in non-small-cell lung cancer in Ontario

BACKGROUND

Although molecular testing has become standard in managing advanced nonsquamous non-small-cell lung cancer (nsclc), most patients undergo minimally invasive procedures, and the diagnostic tumour specimens available for testing are usually limited. A knowledge translation initiative to educate diagnostic specialists about sampling techniques and laboratory processes was undertaken to improve the uptake and application of molecular testing in advanced lung cancer.

METHODS

A multidisciplinary panel of physician experts including pathologists, respirologists, interventional thoracic radiologists, thoracic surgeons, medical oncologists, and radiation oncologists developed a specialty-specific education program, adapting international clinical guidelines to the local Ontario context. Expert recommendations from the program are reported here.

RESULTS

Panel experts agreed that specialists procuring samples for lung cancer diagnosis should choose biopsy techniques that maximize tumour cellularity, and that conservation strategies to maximize tissue for molecular testing should be used in tissue processing. The timeliness of molecular reporting can be improved by pathologist-initiated reflex testing upon confirmation of nonsquamous nsclc and by prompt transportation of specimens to designated molecular diagnostic centres. To coordinate timely molecular testing and optimal treatment, collaboration and communication between all clinicians involved in diagnosing patients with advanced lung cancer are mandatory.

CONCLUSIONS

Knowledge transfer to diagnostic lung cancer specialists could potentially improve molecular testing and treatment for advanced lung cancer patients.

Diagnosing lung cancer in the 21st century: are we ready to meet the challenge of individualized care?

BACKGROUND

Histologic and molecular subtyping have become increasingly important as predictors of treatment benefit in lung cancer. The objective of the present study was to determine whether current diagnostic approaches provide adequate tissue to allow for individualized treatment decisions.

METHODS

Our retrospective cohort study of new lung cancer patients seen at an academic centre between July 2007 and June 2008 collected baseline demographic and diagnostic information, including mode of diagnosis, type of diagnostic material, and pathology diagnosis.

RESULTS

Of the 431 study patients, 20% had stage i or ii non-small-cell lung cancer (nsclc), 24% stage iii disease, and 39% stage iv nsclc. Three quarters of the small-cell lung cancer (sclc) cases were extensive stage. Diagnostically, 18% of patients had sclc; 30%, adenocarcinoma; 27%, squamous-cell cancer; 2%, large-cell carcinoma; 1%, bronchoalveolar carcinoma; 1%, mixed histology; 18%, nsclc not otherwise specified; 4%, other; and 2%, no pathology diagnosis. Surgical pathology material was available in 80% of cases, and cytology material alone in 20%. Surgical pathology material was more common in patients with early-stage than with advanced disease (89% for stages i and ii vs. 74% for stages iii and iv, p < 0.0001). The pathology report included ambiguous terms in 24% of cases: "consistent" (12%), "suspicious" (3%), "favour" (2%), "suggestive" (2%), "likely" (1%), "compatible" with malignancy (1%), "at least" (1%), "atypical" (0.5%), and "no pathology" (1.5%).

CONCLUSIONS

Current diagnostic approaches in most lung cancer patients appear adequate, but complete histopathologic identification is missing in nearly 20% of cases, and some uncertainty as to the final diagnosis is expressed in 24% of pathology reports. Some improvement in diagnostic sampling and pathology reporting are required to allow for implementation of current treatment approaches.

Abstract 2491: Metformin sensitizes human lung cancer xenografts to ionizing radiation: Response of the AMPK pathway

Introduction : Radiation therapy is a standard therapeutic modality in lung cancer (LC). Unfortunately, LC demonstrates radiation resistance and poor response to even high doses of chest radiotherapy. Therefore, there is an urgent need to develop effective and well tolerated radiation sensitizers in LC. Recently, we showed that ionizing radiation (IR) and metformin (MET) activate the energy sensor and tumor suppressor kinase AMP-activated kinase (AMPK). MET enhanced IR activation of AMPK in LC cells and increased the cytotoxicity of IR in clonogenic assays. In the present study we investigated, in human LC xenografts, the radio-sensitizing properties of MET and its effects on the activity of the AMPK pathway in intact tumors.

Methods: A549 cells (2×106) were grafted in the franks of Balb/c immunodeficient athymic nude mice and tumors were left to grow to 100 mm3. MET supplementation was delivered in drinking water at a dose of 250 mg/kg daily, and IR of 10 Gy was delivered as a single fraction 7 days after initiation of metformin administration. Eight weeks later animals were euthanized and tumors where isolated. Half of each tumor was snap frozen for preparation of whole tumor lysates and immunoblotting analysis and the other half was fixed and embedded for immunohistochemistry analysis. Tumour growth kinetics and levels of total AMPK, phosphor (P)-AMPK (P-AMPK Thr172) and P-Acetyl-CoA Carboxylase (ACC) and P-Akt were evaluated.

Results: MET and IR alone inhibited significantly A549 LC xenograft tumor growth. Furthermore, the combined treatment of MET and IR produce an additive effect and inhibited tumor growth more than each treatment alone. Both IR and MET enhanced AMPK phosphorylation and activity detected by ACC phosphorylation. Similar to tumor growth kinetics, the combined treatment of MET+IR enhanced AMPK activity and phosphorylation above the levels of each treatment alone. However, we also detected that MET and IR treatments also increased significantly the total AMPK α subunit levels in tumor tissues with a consistent potentiation of this effect when the two treatments were combined. On the other hand MET showed a tendency to inhibit basal and radiation-induced Akt phosphorylation levels in xenografts. Our immunoblotting results were verified with immunohistochemistry experiments.

Conclusion: Similar to our earlier observations in tissue culture models, the present studies suggest that MET inhibits LC tumour growth and sensitizes them to IR. The two agents mediate both expression and activation of AMPK which appears to be associated with inhibition of Akt. Activation of AMPK by MET and IR in-vivo does not appear to depend on LKB1 as A549 cells are LKB1 null. These results demonstrate the potential of MET to function as a radiation sensitizer in-vivo and support evaluation of this drug in LC clinical trials in combination with radiation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2491. doi:10.1158/1538-7445.AM2011-2491

Amplification of telomerase (hTERT) gene is a poor prognostic marker in non-small-cell lung cancer

Telomerase reactivation is a hallmark of human carcinogenesis. Increased telomerase activity may result from gene amplification and/or overexpression. This study evaluates the prognostic value of hTERT gene amplification and mRNA overexpression in 144 resectable non-small-cell lung cancer (NSCLC) specimens. The hTERT gene copy number was assessed by quantitative polymerase chain reaction (qPCR) on laser-capture microdissected tumour cells of 81 tumours, and by fluorescence in situ hybridisation (FISH) on a subset of 59 tumours. hTERT mRNA level was determined by reverse transcription (RT)-qPCR in 130 tumours. In total, 57% of (46 out of 81) primary NSCLC specimens demonstrated hTERT amplification, which was significantly more common (P<0.001) in adenocarcinoma (30 out of 40) than in squamous cell carcinoma (13 out of 37). The hTERT mRNA overexpression was noted in 74% (94 out of 130) of tumours; it was more frequent in squamous cell than in adenocarcinoma (87 vs 68%, P=0.03). Overexpression was significantly associated with amplification (P=0.03), especially in adenocarcinoma. The hTERT gene amplification was prognostic for shorter recurrence-free survival (hazard ratio=2.16, P=0.03). These data indicate that gene amplification is an important mechanism for hTERT overexpression in lung adenocarcinoma and is an independent poor prognostic marker for disease-free survival in NSCLC.

Brain region-specific and time-dependent decreases of G alpha i2 in amygdala-kindled rats

Immunoreactivity levels of G protein alpha-subunits, Galphas (45 and 52 kDa), Galphai1, and Galphai2, were determined in plasma membranes prepared from ipsilateral amygdala-pyriform cortex (AM/PC), contralateral AM/PC, dorsal hippocampus (DH), and ventral hippocampus (VH) in amygdala-kindled rats 24 h, 1 month, and 3 months after the last seizure. Relative to sham controls, immunoreactivity levels of Galphai2 were significantly reduced in ipsilateral AM/PC and DH, with maximal decreases observed, respectively, at 24 h (26% form control levels) and 1 month (18% from control levels) postseizure. No significant alterations in the levels of Galphai1 or either of the Galphas isoforms were observed. The reduction in Galphai2 levels was, however, not accompanied by measurable changes in Galphai-mediated inhibition of adenylyl cyclase, as estimated by GppNHp modulation of forskolin-activated adenylyl cyclase activity. The present findings add support to the hypothesis that long-term changes in brain functioning following kindling may involve altered expression and/or function of components of the transmembrane signalling cascade, including G proteins.