This is an EGFR mutant non-small cell lung cancer harboring a small population of drug resistant cells (red) prior to drug exposure. These cells contain an amplification of MET. 
(Credit: Eric D. Smith, Dana-Farber Cancer Institute)

Dana-Farber Cancer Institute  —  Even when their tumors are shrinking in response to therapy, some non-small cell lung cancer (NSCLC) patients have a scattering of cancer cells that are undeterred by the drug, causing the tumor to resume its growth, Dana-Farber Cancer Institute and Massachusetts General Hospital (MGH) Cancer Center scientists report in the January issue of Cancer Cell. The findings suggest that identifying such patients and treating them with a combination of drugs from the very start of therapy can produce longer remissions.

The study involves NSCLC tumors which are driven by a mutation in the gene EGFR. Such tumors, which account for about 12 percent of all NSCLC cases in the United States, often recede when treated with a tyrosine kinase inhibitor such as Tarceva(R) or Iressa(R), which targets the faulty EGFR protein.

A few years ago, this same group of investigators showed that NSCLCs being held in check by Tarceva can switch on an alternate growth circuit if they have too many copies of a gene called MET. Such tumors are considered Tarceva- and Iressa-resistant.

In the new paper, investigators led by Pasi Jänne, MD, PhD, of Dana-Faber, and Jeffrey Engelman, MD, PhD, of MGH, found that some patients with EGFR-mutant lung cancers harbor a small number of tumor cells with an overabundance, or “amplification,” of MET even before treatment with a tyrosine kinase inhibitor, and that those few cells are enough to spark drug resistance. One of the triggers for resistance, the researchers found, is HGF, a ligand or “hook” that activates the MET protein.

When activated, HGF works through two entirely different channels to produce drug resistance, the authors report. First, it can generate cell-growth signals through a protein called GAB1. Second, it expands the number of MET-amplified cancer cells, ensuring they will become the dominant type in the lung tumors.

“Not only can HGF spur cell growth on its own, it can speed up the process by which MET-amplified cells emerge and take over the composition of the tumor,” says Jänne, who was co-senior author of the paper with Engelman. In about 20 percent of NSCLC patients who are resistant to Tarceva the mechanism is amplification of MET, and in another 20 percent it may involve HGF.

The findings suggest that patients whose NSCLC tumors harbor even a few MET-amplified cells prior to treatment would benefit from drugs that specifically target those cells, in combination with a tyrosine kinase inhibitor. Jänne notes that such drugs are already being studied in clinical trials.

“Our findings provide a strong rationale for combination treatment strategies as initial therapies for some patients,” Jänne remarks. “This is especially the case in patients with evidence of pre-existing MET amplifications.”

Engelman adds, “A thorough analysis of a patient’s cancer prior to treatment can establish how it would ultimately develop resistance to therapy, allowing us to tailor treatment with greater precision to prevent resistance. For example, cancers found to harbor a small population of cells with pre-existing MET amplification will likely benefit from adding MET inhibitors to initial treatment. Those without such cells may not benefit, and these patients can avoid the added toxicity of MET inhibitors and instead focus on other strategies to prevent their cancers from becoming resistant.” Engelman is an assistant professor of medicine and Jänne an associate professor of medicine at Harvard Medical School.

The study was supported by grants from the National Institutes of Health, American Association for Cancer Research, the V Foundation, American Cancer Society, Hazel and Samuel Bellin Research Fund, and the Ellison Foundation.

The study’s co-lead authors were Alexa Turke of MGH, and Kreshnik Zejnullahu, of Dana-Farber. Co-authors include Yi-Long Wu, of Guangdong General Hospital, Guangzhou, China; Youngchul Song, Dora Dias-Santagata, PhD, Eugene Lifshits, Lecia Sequist, MD, MPH, Sara Akhavanfard, MD, Beow Yeap, and A. John Iafrate, MD, PhD, of MGH; Luca Toschi, MD, Andrew Rogers, and Marzia Capelletti of Dana-Farber; Tony Mok, MD, of the Chinese University of Hong Kong; Neal Lindeman, MD, Carly Murphy, Yun Xiao, and Charles Lee, PhD, of Brigham and Women’s Hospital; and James Christensen, of Pfizer Global Research and Development, La Jolla, Calif.


 

Dana-Farber Cancer Institute (2010, January 22). Combination therapy may be effective against some non-small cell lung cancers. ScienceDaily. Retrieved July 15, 2010, from http://www.sciencedaily.com­ /releases/2010/01/100119121211.htm

International Association for the Study of Lung Cancer, July 15, 2010  —  Analyzing the genes expressed by cancer cells allows for a better understanding of that patient’s specific disease and in turn, a more personalized approach to treatment. But obtaining the RNA from a tumor in the lungs in order to conduct the genetic analysis is a challenging prospect. Currently, lung cancer researchers are limited to using RNA extracted from early-stage tumors removed during surgery. The small quantities of tissue extracted during routine diagnostic biopsies have not been useful to researchers, due to their small size and the variety of ways they have been processed.

Since oftentimes surgery is not an option in advanced lung cancer, genetic analysis of the tumor is critical, there is a need to obtain good quality RNA samples from tumor tissue taken via biopsy, no matter how the biopsy procedure is conducted.

In a study in the July edition of the Journal of Thoracic Oncology, Malcolm H. Lawson describes a process to successfully obtain and to store high quality RNA from lung tumor biopsies. Lawson and fellow researchers at the Cancer Research UK Cambridge Research Institute and Papworth Hospital, both in the United Kingdom, received consent from patients to take extra biopsies for research purposes during the diagnostic procedure. Biopsies were obtained using the three most frequently used techniques — endobronchial biopsy forceps, transbronchial needle aspirate — or CT-guided needle biopsy. Acceptable RNA for gene expression analysis was extracted from 72 percent of lung cancer biopsies.

Lawson and team immediately froze some of the biopsies in liquid nitrogen, while the others were first treated with an RNA preservative (RNAlater) before freezing. Use of the RNA preservative resulted in higher quality, more intact RNA from biopsies taken via all methods.

Storage in the RNA preservative doubled the number of biopsies that met the minimum yield and quality criteria for analysis compared with immediate freezing (10 of 16 biopsies vs. 5 of 16). Using the RNA preservative, 70 percent of biopsies taken by needle aspiration were suitable for analysis compared with 40 percent frozen, and 50 percent of the RNA preservative endobronchial biopsies were acceptable compared with 17 percent of the frozen ones. A full 100 percent of the CT-guided needle biopsies met the criteria when treated with RNA preservative.

“This is a novel model for tissue banking lung cancer diagnostic specimens that greatly increases the number and type of tumors available for gene expression studies,” Dr. Lawson said. “If used widely, it makes personalized medicine for lung cancer patients a more practical proposition.”


Journal Reference:

  1. Malcolm H. Lawson, Doris M. Rassl, Natalie M. Cummings, Roslin Russell, Jaymin B. Morjaria, James D. Brenton, Gillian Murphy, Robert C. Rintoul. Tissue Banking of Diagnostic Lung Cancer Biopsies for Extraction of High Quality RNA. Journal of Thoracic Oncology, 2010; : 1 DOI: 10.1097/JTO.0b013e3181ddbbe9

Top of Form

International Association for the Study of Lung Cancer (2010, July 15). New method of tissue banking makes gene analysis more practical for lung cancer. ScienceDaily. Retrieved July 15, 2010, from http://www.sciencedaily.com­ /releases/2010/07/100715123416.htm

Children’s Hospital Boston, Boston, MA, July 2010  —  Cancer stem cells have enticed scientists because of the potential to provide more durable and widespread cancer cures by identifying and targeting the tumor’s most voracious cells. Now, researchers at Children’s Hospital Boston and their colleagues have identified cancer stem cells in a model of the most common form of human lung cancer and, more significantly, have found that the cancer stem cells may vary from tumor to tumor, depending upon the tumor’s genetic signature.

“Our study shows the cancer stem cell hypothesis is true in some lung cancers,” said senior author Carla Kim, PhD, an assistant professor in the Stem Cell Program at Children’s Hospital Boston and the department of genetics at Harvard Medical School (HMS). “It also shows, from one lung cancer to another, the cancer stem cells are not the same.”

Cancer stem cells are a subset of cancer cells believed to elude conventional treatments and eventually regenerate a tumor. Experimentally, they show up as cells that can be extracted from a tumor and transplanted to form a new tumor, from which the same tumor-propagating cells can again be extracted and transplanted with the same result. According to Kim, this is the first serial transplantation study to identify lung cancer tumor-propagating cells.

The findings, published in the July 2 Cell Stem Cell, connect the cancer stem cell hypothesis with molecular profiling of tumors (sometimes called personalized medicine). The results may allow researchers to combine stem cell biology with genetic typing to identify what drives the cancerous behavior of each patient’s tumor and to develop new therapeutic targets.

In their study, Kim and her colleagues looked at mouse models of the three most commonly mutated genes in human lung cancer — K-RAS and p53 (two genes predominantly mutated in adenocarcinomas of smokers) and one gene more often found mutated in non-smokers (EGFR). Led by HMS graduate student Stephen Curtis, the team identified cancer stem cells in a model combining the K-RAS and p53 oncogenic mutations. When the researchers serially transplanted the cancer stem cells from this model into the lungs of mice, new tumors formed.

The cancer stem cells in the K-RAS/p53 mice sported one telltale molecule (Sca1), found on the surface of a tiny 1 percent of all the tumor cells. In two other models of lung cancer, cells with that molecular marker were just as rare, but they failed to distinguish themselves as cancer stem cells. In the K-RAS model, all tumor cells were equally likely to propagate tumors. In the EGFR model, only the tumor cells lacking that molecule could propagate tumors.

“Our paper says the identity of the cancer stem cells could be different between one patient’s lung tumor and another’s,” said Kim. “This will be crucial for researchers to consider as they design therapies to target specific cancer cell populations.” The team did not test any drug interventions or human lung cancer samples. These are the next important steps, she said.

The findings may also help other researchers identify cancer stem cells by taking into account the cancer’s genetic signature. For patients, optimal treatment may rely on a combination of the tumor genotype and its tumor-propagating cell phenotype.

“Our idea is that, even though many patients’ tumors may look similar, in order to offer truly personalized and effective targeted therapy, we need to know the genotype of a patient’s tumor and successfully identify the cells that maintain that tumor,” said Curtis.

Funding was provided by the U.S. Department of Defense, Air Force, Office of Scientific Research, National Defense Science and Engineering Fellowship; the American Cancer Society; Dana Farber Harvard Cancer Center Lung Cancer SPORE grant; the V Foundation; the Harvard Stem Cell Institute; National Institutes of Health/National Cancer Institute; and The Lung Cancer Alliance.


Journal Reference:

Stephen J. Curtis, Kerstin W. Sinkevicius, Danan Li, Allison N. Lau, Rebecca R. Roach, Raffaella Zamponi, Amber E. Woolfenden, David G. Kirsch, Kwok-Kin Wong, Carla F. Kim. Primary Tumor Genotype Is an Important Determinant in Identification of Lung Cancer Propagating Cells. Cell Stem Cell, Volume 7, Issue 1, 127-133, 2 July 2010 DOI:

Children’s Hospital Boston (2010, July 5). Cancer stem cells are not ‘one size fits all,’ lung cancer models show. ScienceDaily. Retrieved July 15, 2010, from http://www.sciencedaily.com­ /releases/2010/07/100701131447.html

International Association for the Study of Lung Cancer, July 15, 2010  —  Analyzing the genes expressed by cancer cells allows for a better understanding of that patient’s specific disease and in turn, a more personalized approach to treatment. But obtaining the RNA from a tumor in the lungs in order to conduct the genetic analysis is a challenging prospect. Currently, lung cancer researchers are limited to using RNA extracted from early-stage tumors removed during surgery. The small quantities of tissue extracted during routine diagnostic biopsies have not been useful to researchers, due to their small size and the variety of ways they have been processed.

Since oftentimes surgery is not an option in advanced lung cancer, genetic analysis of the tumor is critical, there is a need to obtain good quality RNA samples from tumor tissue taken via biopsy, no matter how the biopsy procedure is conducted.

In a study in the July edition of the Journal of Thoracic Oncology, Malcolm H. Lawson describes a process to successfully obtain and to store high quality RNA from lung tumor biopsies. Lawson and fellow researchers at the Cancer Research UK Cambridge Research Institute and Papworth Hospital, both in the United Kingdom, received consent from patients to take extra biopsies for research purposes during the diagnostic procedure. Biopsies were obtained using the three most frequently used techniques — endobronchial biopsy forceps, transbronchial needle aspirate — or CT-guided needle biopsy. Acceptable RNA for gene expression analysis was extracted from 72 percent of lung cancer biopsies.

Lawson and team immediately froze some of the biopsies in liquid nitrogen, while the others were first treated with an RNA preservative (RNAlater) before freezing. Use of the RNA preservative resulted in higher quality, more intact RNA from biopsies taken via all methods.

Storage in the RNA preservative doubled the number of biopsies that met the minimum yield and quality criteria for analysis compared with immediate freezing (10 of 16 biopsies vs. 5 of 16). Using the RNA preservative, 70 percent of biopsies taken by needle aspiration were suitable for analysis compared with 40 percent frozen, and 50 percent of the RNA preservative endobronchial biopsies were acceptable compared with 17 percent of the frozen ones. A full 100 percent of the CT-guided needle biopsies met the criteria when treated with RNA preservative.

“This is a novel model for tissue banking lung cancer diagnostic specimens that greatly increases the number and type of tumors available for gene expression studies,” Dr. Lawson said. “If used widely, it makes personalized medicine for lung cancer patients a more practical proposition.”


Journal Reference:

  1. Malcolm H. Lawson, Doris M. Rassl, Natalie M. Cummings, Roslin Russell, Jaymin B. Morjaria, James D. Brenton, Gillian Murphy, Robert C. Rintoul. Tissue Banking of Diagnostic Lung Cancer Biopsies for Extraction of High Quality RNA. Journal of Thoracic Oncology, 2010; : 1 DOI: 10.1097/JTO.0b013e3181ddbbe9

Top of Form

International Association for the Study of Lung Cancer (2010, July 15). New method of tissue banking makes gene analysis more practical for lung cancer. ScienceDaily. Retrieved July 15, 2010, from http://www.sciencedaily.com­ /releases/2010/07/100715123416.htm

ScienceDaily (July 15, 2010) — Analyzing the expression of particular genes in lung cancers could soon allow researchers to identify groups of patients who are likely to benefit most from treatment with angiogenesis-inhibitor drugs, a Spanish team reports.

Dr Eloisa Jantus from the General University Hospital of Valencia reports new findings from an analysis of 135 lung cancer specimens. She and her colleagues, led by Dr Carlos Camps, evaluated the expression of 8 different genes related to vascular endothelial growth factor (VEGF), a molecule that helps tumors develop the blood supply they need to grow larger. VEGF is a key target for new “anti-angiogenesis” drugs that aim to arrest this process.

“The vascular endothelial growth factor (VEGF) family of ligands and receptors has an important role in tumor angiogenesis,” Dr Jantus said. “We studied the expression, at molecular level, of the members of this family in tumor samples as well as in normal lung tissues in order to understand their role in tumor development and prognosis.”

The group measured the expression of the 8 genes, including VEGF A, -B, -C and PIGF, tyrosine-kinase receptors VEGFR-1, VEGFR-2 and VEGFR-3. In addition to these receptors, they also studied related genes for neuropilins NRP1 and NRP2.

The researchers then correlated gene expression levels with important clinical outcomes, including overall survival and the time to tumor progression, in patients whose tumors were surgically removed.

“Patients whose tumors expressed high levels of VEGF-A and VEGFR-1 tended to have a worse prognosis in terms of progression-free survival and overall survival,” Dr Jantus said. “The subgroup of patients with high levels of expression of VEGF-A and VEGFR-1 showed a 30% shorter time to progression and overall survival, when compared to those with low expression levels.”

The findings provide early clues that ‘angiogenic profiles’ could define subgroups of patients who will better benefit from the use of anti-angiogenic therapies, the researchers say.

“We think that it seems improbable that a single angiogenic marker will provide all of the relevant clinical information because only one biomarker cannot reflect the complexity of the angiogenic process; however, when the markers were considered in combination, they provided a more comprehensive pattern or profile, significantly improving their prognostic value.”

These angiogenic profiles need validation in larger groups of patients before they can be implemented in the clinic, the researchers note, however they represent an emerging way to improve lung cancer therapy by tailoring it to the characteristics of individual patients and their tumors.


Source:  European Society for Medical Oncology