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Posts Tagged ‘Triple-negative breast cancer’


Targeted Therapy for Triple Negative Breast Cancer

Curator: Larry H. Bernstein, MD, FCAP

LPBI

 

Triple-Negative Breast Cancer Target Is Found

May 17, 2016   Researchers at UC Berkeley discover a target that drives cancer metabolism in triple-negative breast cancer.
http://www.technologynetworks.com/Genotyping/news.aspx?ID=191502

UC Berkeley researchers have found a long-elusive Achilles’ heel within “triple-negative” breast tumors, a common type of breast cancer that is difficult to treat. The scientists then used a drug-like molecule to successfully target this vulnerability, killing cancer cells in the lab and shrinking tumors in mice.

“We were looking for targets that drive cancer metabolism in triple-negative breast cancer, and we found one that was very specific to this type of cancer,” said Daniel K. Nomura, an associate professor of chemistry and of nutritional sciences and toxicology at UC Berkeley and senior author for the study, which is published online ahead of print in Cell Chemical Biology.

Triple-negative breast cancers account for about one in five breast cancers, and they are deadlier than other forms of breast cancer, in part because no drugs have been developed to specifically target these tumors.

Triple-negative breast cancers do not rely on the hormones estrogen and progesterone for growth, nor on human epidermal growth factor receptor 2 (HER2). Because they do not depend on these three targets, they are not vulnerable to modern hormonal therapies or to the HER2-targeted drug Herceptin (trastuzumab).

Instead, oncologists treat triple-negative breast cancer with older chemotherapies that target all dividing cells. If triple-negative breast cancer spreads beyond the breast to distant sites within the body, an event called metastasis, there are few treatment options.

Tumor cells develop abnormal metabolism, which they rely on to get the energy boost they need to fuel their rapid growth. In their new study, the research team used an innovative approach to search for active enzymes that triple-negative breast cancers use differently for metabolism in comparison to other cells and even other tumors.

Inhibiting cancer metabolism

They discovered that cells from triple-negative breast cancer cells rely on vigorous activity by an enzyme called glutathione-S-transferase Pi1 (GSTP1). They showed that in cancer cells, GSTP1 regulates a type of metabolism called glycolysis, and that inhibition of GSTP1 impairs glycolytic metabolism in triple-negative cancer cells, starving them of energy, nutrients and signaling capability. Normal cells do not rely as much on this particular metabolic pathway to obtain usable chemical energy, but cells within many tumors heavily favor glycolysis.

Co-author Eranthie Weerapana, an associate professor of chemistry at Boston College, developed a molecule named LAS17 that tightly and irreversibly attaches to the target site on the GSTP1 molecule. By binding tightly to GSTP1, LAS17 inhibits activity of the enzyme. The researchers found that LAS17 was highly specific for GSTP1, and did not attach to other proteins in cells.

According to Nomura, LAS17 did not appear to have toxic side effects in mice, where it shrank tumors grown to an invasive stage from surgically transplanted, human, triple-negative breast cancer cells that had long been maintained in lab cultures.

The research team intends to continue studying LAS17, Nomura said, with the next step being to study tumor tissue resected from human triple-negative breast cancers and transplanted directly into mice.

“Inhibiting GSTP1 impairs glycolytic metabolism,” Nomura said. “More broadly, this inhibition starves triple-negative breast cancer cells, preventing them from making the macromolecules they need, including the lipids they need to make membranes and the nucleic acids they need to make DNA. It also prevents these cells from making enough ATP, the molecule that is the basic energy fuel for cells.”

Beyond the metabolic role they first sought to track down, GSTP1 also appears to aid signaling within triple-negative breast cancer cells, helping to spur tumor growth, the researchers found.

Technique identifies Achilles’ heels

Nomura said it was surprising that a single, unique target emerged from the research team’s search.

The method used by the researchers, called “reactivity-based chemoproteomics,” can quickly lead to specific targetable sites — the Achilles’ heels — on proteins of interest, and eventually to drug development strategies, Nomura said.

The approach is to search for protein targets that are actively functioning within cells, instead of first using the well-trod path of surveying all genes to identify the specific genes that have taken the first step toward protein production. With that more conventional strategy, the switching on, or “expression,” of genes is evidenced by the easily quantified molecule called messenger RNA, made by the cell from a gene’s DNA template.

Nomura’s team instead first used chemical probes that can react with certain configurations of two of the amino acid building blocks of protein — cysteine and lysine — known to be involved in several kinds of important structural and functional transitions that active proteins can undergo.

“A lot can happen after the first step in protein production, and we believe our method for identifying fully formed, active proteins is more useful for tracking down relevant differences in cellular physiology,” Nomura said.

The researchers analyzed and compared cells from five distinct triple-negative breast cancers that had been grown in cell cultures for generations, along with cells from four distinct breast cancers that were not triple negative.

The scientists used a chemical identification technique known as mass spectrometry to narrow down the set of proteins that had active lysines and cysteines to just those that were metabolic enzymes. Only then did they use the more conventional approach of measuring gene expression in the different cancer cell types.

GSTP1 was the only metabolically active enzyme that was specifically expressed only in triple-negative breast cancer cells compared to other breast cancer cell types, the researchers found. Separate analysis of databases of human breast cancer by UC San Francisco co-authors confirmed that GSTP1 is overexpressed in patients with triple-negative breast cancers in comparison to patients with other breast cancers.

In addition to Nomura and Weerapana, study authors included Sharon Louie, Elizabeth Grossman, Lucky Ding, Tucker Huffman and David Miyamoto, from UC Berkeley; Roman Camarda and Andrei Goga, from UC San Francisco, and Lisa Crawford, from Boston College. Study funders included the National Institutes of Health, the American Cancer Society, the U.S. Department of Defense, and the Searle Scholar Foundation.

 

Triple-negative breast cancer target is found

UC Berkeley researchers have found a long-elusive Achilles’ heel within “triple-negative” breast tumors, a common type of breast cancer that is difficult to treat. The scientists then used a drug-like molecule to successfully target this vulnerability, killing cancer cells in the lab and shrinking tumors in mice.

“We were looking for targets that drive cancer metabolism in triple-negative breast cancer, and we found one that was very specific to this type of cancer,” said Daniel K. Nomura, an associate professor of chemistry and of nutritional sciences and toxicology at UC Berkeley and senior author for the study, which is published online ahead of print on May 12 in Cell Chemical Biology.

Triple-negative breast cancers account for about one in five breast cancers, and they are deadlier than other forms of breast cancer, in part because no drugs have been developed to specifically target these tumors.

Triple-negative breast cancers do not rely on the hormones estrogen and progesterone for growth, nor on human epidermal growth factor receptor 2 (HER2). Because they do not depend on these three targets, they are not vulnerable to modern hormonal therapies or to the HER2-targeted drug Herceptin (trastuzumab).

Instead, oncologists treat triple-negative breast cancer with older chemotherapies that target all dividing cells. If triple-negative breast cancer spreads beyond the breast to distant sites within the body, an event called metastasis, there are few treatment options.

Tumor cells develop abnormal metabolism, which they rely on to get the energy boost they need to fuel their rapid growth. In their new study, the research team used an innovative approach to search for active enzymes that triple-negative breast cancers use differently for metabolism in comparison to other cells and even other tumors.

Inhibiting cancer metabolism

They discovered that cells from triple-negative breast cancer cells rely on vigorous activity by an enzyme called glutathione-S-transferase Pi1 (GSTP1). They showed that in cancer cells, GSTP1 regulates a type of metabolism called glycolysis, and that inhibition of GSTP1 impairs glycolytic metabolism in triple-negative cancer cells, starving them of energy, nutrients and signaling capability. Normal cells do not rely as much on this particular metabolic pathway to obtain usable chemical energy, but cells within many tumors heavily favor glycolysis.

for mor see.. http://news.berkeley.edu/2016/05/12/triple-negative-breast-cancer-target-is-found/

 

GSTP1 Is a Driver of Triple-Negative Breast Cancer Cell Metabolism and Pathogenicity

Sharon M. Louie, Elizabeth A. Grossman, Lisa A. Crawford….., Eranthie Weerapana, Daniel K. Nomura
Figure thumbnail fx1
  • We used chemoproteomics to profile metabolic drivers of breast cancer
  • GSTP1 is a novel triple-negative breast cancer-specific target
  • GSTP1 inhibition impairs triple-negative breast cancer pathogenicity
  • GSTP1 inhibition impairs GAPDH activity to affect metabolism and signaling

Breast cancers possess fundamentally altered metabolism that fuels their pathogenicity. While many metabolic drivers of breast cancers have been identified, the metabolic pathways that mediate breast cancer malignancy and poor prognosis are less well understood. Here, we used a reactivity-based chemoproteomic platform to profile metabolic enzymes that are enriched in breast cancer cell types linked to poor prognosis, including triple-negative breast cancer (TNBC) cells and breast cancer cells that have undergone an epithelial-mesenchymal transition-like state of heightened malignancy. We identified glutathione S-transferase Pi 1 (GSTP1) as a novel TNBC target that controls cancer pathogenicity by regulating glycolytic and lipid metabolism, energetics, and oncogenic signaling pathways through a protein interaction that activates glyceraldehyde-3-phosphate dehydrogenase activity. We show that genetic or pharmacological inactivation of GSTP1 impairs cell survival and tumorigenesis in TNBC cells. We put forth GSTP1 inhibitors as a novel therapeutic strategy for combatting TNBCs through impairing key cancer metabolism and signaling pathways.

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Blocking miRNAs in Triple Negative Breast Cancer

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Why Blocking microRNAs in Triple Negative Breast Cancer Is so Difficult

http://www.genengnews.com/gen-news-highlights/why-blocking-micrornas-in-triple-negative-breast-cancer-is-so-difficult/81252048/

New research uncovers why attempts at blocking microRNAs for triple negative breast cancer often fail. [National Breast Cancer Foundation]

http://www.genengnews.com/Media/images/GENHighlight/thumb_Dec2_2015_NationalBreastCancerFoundation_MicroRNAs4198253108.jpg

 

While a triple negative score is hardly ever a good thing, for breast cancer it is especially troubling. Triple-negative breast cancer (TNBC) refers to a disease scenario where the cancer cells do not express the genes for estrogen, progesterone, or HER2/neu receptors simultaneously—making this cancer particularly aggressive and difficult to treat as most chemotherapies target one of these receptors.

Over the past several years, researchers have discovered that various microRNAs (miRNAs) underlie the expression of certain genes that can enable cancer cells to proliferate faster. However, the ability to block these miRNAs in TNBC has been met with failure. Yet now, scientists from Thomas Jefferson University in Philadelphia believe they have discovered the reason conventional methods to block these miRNAs has been thus far unsuccessful.

“Triple-negative breast cancer is one of the most aggressive forms of breast cancer, and there’s been a lot of excitement in blocking the microRNAs that appear to make this type of cancer grow faster and resist conventional treatment,” explained senior author Eric Wickstrom, Ph.D., professor in the department of biochemistry and molecular biology at TJU. “However blocking microRNAs hasn’t met with great success and this paper offers one explanation for why that might be the case.”

The findings from this study were published online today in PLOS ONE through an article entitled “Non-specific blocking of miR-17-5p guide strand in triple negative breast cancer cells by amplifying passenger strand activity.” Insight from this study may enable new and more effective design of blockers against previously intractable miRNAs.

“Triple negative breast cancer strikes younger women, tragically killing them in as little as two years,” noted lead author Yuan-Yuan Jin, a doctoral candidate in the department of biochemistry and molecular biology at TJU. “Only chemotherapy and radiation are approved therapies for triple negative breast cancer. We want to treat a genetic target that will keep patients alive with a good quality of life.”

The investigators targeted the miRNA molecule miR-17, which has been shown previously to cause a surge in TNBC growth by alternating genes that would normally signal a diseased or early cancerous cell to die—specifically, the tumor suppressor genes PDCD4 and PTEN.

Although, when the TJU researchers tried to reduce the levels of miR-17 in TNBC cells, rather than increase the levels of the tumor suppressor genes, as they had anticipated, they saw an even larger decrease in these genes than unmodified controls.

The TJU team was acting under the current assumptions that miRNA, which are double stranded, only silence genes using one of their two strands, which is complementary to parts of the messenger RNA coding sequence. The matching, or so-called passenger strand, was thought to be discarded and degraded by the cell.

Using a method to silence RNAs, which involves flooding the cell with modified RNA sequences that mimic the passenger strand and bind to the single-stranded microRNA before it reaches its target, the TJU team saw more silencing of the PDCD4 and PTEN genes.  After some bioinformatic and folding energy calculations, the authors realized that both strands of miR-17 were active in downregulating the tumor suppressor genes.

“Rather than blocking miR-17, we were inadvertently boosting its levels, and, therefore, boosting the cell’s cancerous potential,” noted Jin.

The results of the current study should help to open a pathway to designing specific blockers of one microRNA strand without imitating the opposite strand. Dr. Wickstrom added that “we are now testing new miR-17 blocker designs made possible by these results.”

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Latest research efforts reported in the San Antonio Breast Cancer Symposium, 2012

Curator: Ritu Saxena, Ph.D.

‘Triple negative breast cancer’ or TNBC, as the name suggests, is a classification of breast cancers lacking the expression of estrogen receptor (ER) and progesterone receptor expression as well as amplification of the human epidermal growth factor receptor 2 (HER2).

Unlike other breast cancer types, treating TNBC is a challenge mainly because of the absence of well-defined molecular targets and because of disease heterogeneity. Currently, neoadjuvant chemotherapies are in use to treat TNBC patients. Some, around 30%, patients respond completely to neoadjuvant chemotherapy and have good outcomes after surgery. However, if there is a residual disease after therapy, outcomes are poor.

Therefore, current focus of the field is to first understand the complexity of the disease, both at genomic and molecular level and look for targets. Also, several combination chemotherapies are currently under trial to determine the efficacy, overall response rate, progression-free survival and other relevant factors for patients suffering with different forms of TNBC.

Recently, in the San Antonio Breast Cancer Symposium (SABCS 2012), several abstarcts related to TNBC research, both clinical and pre-clinical. Here is a compilation of some of the abstracts and their relevance in the field of TNBC research:

Triple Negative Breast Cancer: Subtypes, Molecular Targets, and Therapeutic Approaches, Pietenpol JA, Vanderbilt-Ingram Cancer Center; Vanderbilt University School of Medicine (Nashville, TN), Abstract no. ES2-2.

In order to better understand the complexity of TNBC, an integrative and comprehensive genomic and molecular analysis is required. The analysis would give important cues to developing and administering effective therapeutic agents. The group has compiled an extensive number of TNBC gene expression profiles and initiated molecular subtyping of the disease. Differential GE was used to designate 25 TNBC cell line models representative of the following subtypes:

  •  two basel-like TNBC subtypes with cell cycle and DDR gene expression signatures (BL1 and BL2);
  • two mesenchymal subtypes with high expression of genes involved in differentiation and growth factor pathways (M and MSL);
  • an immunomodulatory (IM) type;
  • a luminal subtype driven by androgen signaling (LAR)

The pharmacological drugs were chosen on the basis of the genetic pathways active in the cell lines with the abovementioned TNBC subtypes. It was observed that BL1 and BL2 subtype cell lines respond to cisplatin. Mesenchymal, basal, and luminal subtype lines with aberrations in PI3K signaling and have the greatest sensitivity to PI3K inhibitors.

The LAR subtype cell lines express AR and are uniquely sensitive to bicalutamide (AR antagonist). The experiment was a proof-of-concept that the best therapy could be based on TNBC subtypes.

The group has also developed a web-based subtyping tool referred to as “TNBCtype,” for candidate TNBC tumor samples using our gene expression metadata and classification methods. The approach would enable alignment of TNBC patients to appropriate targeted therapies.

The Clonal and Mutational Composition of Triple Negative Breast Cancers: Aparicio S, University of British Columbia (Vancouver, BC), Canada. Abstract no. ES2-3.

The abstract is on the same lines, TNBC heterogeneity that is. The concept of clonal heterogeneity in cancers, the spatial and temporal variation in clonal composition, is the focal point of the discussion. The group has developed next generation sequencing approaches and applied them to the understanding of mutational and clonal composition of primary TNBC. They have demonstrated that both mutational composition and clonal structure of primary TNBC is in fact a complete spectrum, a notion that is far from the previous one that stated TNBC to be a distinct disease. The authors add “clonal analysis suggests a means by which the genetic complexity might be reduced by following patient evolution over time and space.” The specific implications of the mutational and transcriptome landscapes of TNBC in relation to possible disease biologies were discussed in the symposium.

Profiling of triple-negative breast cancers after neoadjuvant chemotherapy identifies targetable molecular alterations in the treatment-refractory residual disease:

Balko JM, etal, Vanderbilt University (Nashville, TN); Foundation Medicine, (Cambridge, MA); Instituto Nacional de Enfermedades Neoplásicas, Lima, Peru

In the absence of hormone receptors and hence lack of targets, Neoadjuvant chemotherapy (NAC) is increasingly used in patients with TNBC. NAC can induce a pathologic complete response (pCR) in ∼30% of patients which portends a favorable prognosis. In contrast, patients with residual disease (RD) in the breast at surgical resection exhibit worse outcomes. The authors hypothesize that “profiling residual TNBC after NAC would identify molecularly targetable lesions in the chemotherapy resistant component of the tumor and that the persistent tumor cells would mirror micro-metastases which ultimately recur in such patients.” The researchers utilized targeted next generation sequencing (NGS) for 182 oncogenes and tumor suppressors in a CLIA certified lab (Foundation Medicine, Cambridge, MA) and gene expression profiling (NanoString) of the RD after NAC in 102 patients with TNBC. The RD was stained for Ki67, which has been reported to predict outcome after NAC in unselected breast cancers. Out of the 89 evaluable post-NAC tumors, 57 (64%) were basal-like; 19% HER2-enriched; 6% luminal A; 6% luminal B and 5% normal-like. Of 81 tumors evaluated by NGS, 89% demonstrated mutations in TP53, 27% were MCL1-amplified, and 21% were MYC-amplified.

Several pathways were found to be altered:

  • PI3K/mTOR pathway (AKT1-3, PIK3CA, PIK3R1, RAPTOR, PTEN, and TSC1)
  • Cell cycle genes (amplifications of CDK2, CDK4, and CDK6, CCND1-3, and CCNE1); loss of RB
  • DNA repair pathway (BRCA1/2, ATM)
  • Ras/MAPK pathway (KRAS, RAF1, NF1)
  • Sporadic growth factor receptor (amplifications occurred in EGFR, KIT, PDGFRA, PDGFRB, MET, FGFR1, FGFR2, and IGF1R.

NGS identified 7 patients with ERBB2 gene amplification. NGS could assist in the identification of ERBB2-overexpressing tumors misclassified at the time of diagnosis.

Amplifications of MYC were independently associated with poor recurrence-free survival (RFS) and overall survival (OS). In contrast to the earlier notion, high post-NAC Ki67 score did not predict poor RFS or OS in this predominantly TNBC cohort.

The authors concluded that “the diversity of lesions in residual TNBCs after NAC underscores the need for powerful and broad molecular approaches to identify actionable molecular alterations and, in turn, better inform personalized therapy of this aggressive disease.”

Identification of Novel Synthetic-Lethal Targets for MYC-Driven Triple-Negative Breast Cancer: Goga A, etal, UCSF (San Francisco, CA), Abstract No. S3-8

Reiterating the greatest challenge of the TNBC treatment, no targeted agents currently exist against TNBC. The group at UCSF has discovered that TNBC frequently express high levels of the MYC proto-oncogene. The discovery has led them to identify new “synthetic-lethal” strategies to selectively kill TNBC with MYC overexpression. “Synthetic lethality arises when a combination of mutations in two or more genes leads to cell death, whereas a mutation in only one of these genes has little effect. Using this strategy, we can take advantage of the elevated MYC signaling in TNBC to selectively kill them, while sparing normal tissues in which MYC is expressed at much lower levels”

The researchers performed a shRNA synthetic-lethal screen in the human mammary epithelial cells (HMEC), to identify new molecules, such as cell cycle kinases, which when inhibited can preferentially kill TNBC cells. A high-throughput screen of ∼2000 shRNAs, that target the human kinome (∼ 600 kinases) when performed, led to the identification of 13 kinases whose inhibition by >1 shRNAs gave rise to >50% inhibition of cell growth. ARK5 and GSK3A were the two other kinases that were shown to have a synthetic-lethal interaction with MYC. Since these two kinases have been identified in other studies, it gives validity to the ability to the methods of Goga etal in identifying synthetic-lethal targets. The group is currently characterizing and validating the 11 novel targets identified in this screen, using human cancer cell lines as well as mouse cancer models to determine the impact of inhibiting these targets on triple-negative breast cancer development and proliferation.

Reference:

Dent R, etal.  Triple-negative breast cancer: clinical features and patterns of recurrence (2007) Clin Cancer Res 13, 4429-4434.

Lehmann BD, etal. Identification of human triple-negative breast cancer subtypes and preclinical models for selection of targeted therapies (2011) J Clin Invest. 121: 2750-67.

Chen X, etal. TNBCtype: A Subtyping Tool for Triple- Negative Breast Cancer. (2012) Cancer informatics 11, 147-156.

Abstracts presented in SABCS 2012 can be accessed here.

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The unfortunate ending of the Tower of Babel construction project and its effect on modern imaging-based cancer patients’ management


The story of the city of Babel is recorded in the book of Genesis 11 1-9. At that time, everyone on earth spoke the same language.

Picture: Pieter Bruegel the Elder: The Tower of Babel_(Vienna)

It is probably safe to assume that medical practitioners at that time were reporting the status of their patients in a standard manner. Although not mentioned, one might imagine that, at that time, ultrasound or MRI scans were also reported in a standard and transferrable manner. The people of Babel noticed the potential in uniform communication and tried to build a tower so high that it would  reach the gods. Unfortunately, God did not like that, so he went down (in person) and confounded people’s speech, so that they could not understand each another. Genesis 11:7–8.

This must be the explanation for our inability to come to a consensus on reporting of patients’ imaging-outcome. Progress in development of efficient imaging protocols and in clinical management of patients is withheld due to high variability and subjectivity of clinicians’ approach to this issue.

Clearly, a justification could be found for not reaching a consensus on imaging protocols: since the way imaging is performed affects the outcome, (i.e. the image and its interpretation) it takes a long process of trial-and-error to come up with the best protocol.  But, one might wonder, wouldn’t the search for the ultimate protocol converge faster if all practitioners around the world, who are conducting hundreds of clinical studies related to imaging-based management of cancer patients, report their results in a standardized and comparable manner?

Is there a reason for not reaching a consensus on imaging reporting? And I’m not referring only to intra-modality consensus, e.g. standardizing all MRI reports. I’m referring also to inter-modality consensus to enable comparison and matching of reports generated from scans of the same organ by different modalities, e.g. MRI, CT and ultrasound.

As developer of new imaging-based technologies, my personal contribution to promoting standardized and objective reporting was the implementation of preset reporting as part of the prostate-HistoScanning product design. For use-cases, as demonstrated below, in which prostate cancer patients were also scanned by MRI a dedicated reporting scheme enabled matching of the HistoScanning scan results with the prostate’s MRI results.

The MRI reporting scheme used as a reference is one of the schemes offered in a report by Miss Louise Dickinson on the following European consensus meeting : Magnetic Resonance Imaging for the Detection, Localisation, and Characterisation of Prostate Cancer: Recommendations from a European Consensus Meeting, Louise Dickinson a,b,c,*, Hashim U. Ahmed a,b, Clare Allen d, Jelle O. Barentsz e, Brendan Careyf, Jurgen J. Futterer e, Stijn W. Heijmink e, Peter J. Hoskin g, Alex Kirkham d, Anwar R. Padhani h, Raj Persad i, Philippe Puech j, Shonit Punwani d, Aslam S. Sohaib k, Bertrand Tomball,Arnauld Villers m, Jan van der Meulen c,n, Mark Emberton a,b,c,

http://www.europeanurology.com/article/S0302-2838(10)01187-5

Image of MRI reporting scheme taken from the report by Miss Louise Dickinson

The corresponding HistoScanning report is following the same prostate segmentation and the same analysis plans:


Preset reporting enabling matching of HistoScanning and MRI reporting of the same case.

It is my wish that already in the near-future, the main radiology societies (RSNA, ESR, etc..) will join together to build the clinical Imaging’s “Tower of Babel” to effectively address the issue of standardizing reporting of imaging procedures. This time it will not be destroyed…:-)

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Knowing the tumor’s size and location, could we target treatment to THE ROI by applying imaging-guided intervention?


Knowing the tumor’s size and location, could we target treatment to THE ROI by applying imaging-guided intervention?

Author: Dror Nir, PhD

 

Advances in techniques for cancer lesions’ detection and localisation [1-6] opened the road to methods of localised (“focused”) cancer treatment [7-10].  An obvious challenge on the road is reassuring that the imaging-guided treatment device indeed treats the region of interest and preferably, only it.

A step in that direction was taken by a group of investigators from Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada who evaluate the feasibility and safety of magnetic resonance (MR) imaging–controlled transurethral ultrasound therapy for prostate cancer in humans [7]. Their study’s objective was to prove that using real-time MRI guidance of HIFU treatment is possible and it guarantees that the location of ablated tissue indeed corresponds to the locations planned for treatment. Eight eligible patients were recruited.

 

The setup

 

Treatment protocol

 

The result

 

“There was excellent agreement between the zone targeted for treatment and the zone of thermal injury, with a targeting accuracy of ±2.6 mm. In addition, the temporal evolution of heating was very consistent across all patients, in part because of the ability of the system to adapt to changes in perfusion or absorption properties according to the temperature measurements along the target boundary.”

 

Technological problems to be resolved in the future:

“Future device designs could incorporate urinary drainage during the procedure, given the accumulation of urine in the bladder during treatment.”

“Sufficient temperature resolution could be achieved only by using 10-mm-thick sections. Our numeric studies suggest that 5-mm-thick sections are necessary for optimal three-dimensional conformal heating and are achievable by using endorectal imaging coils or by performing the treatment with a 3.0-T platform.”

Major limitation: “One of the limitations of the study was the inability to evaluate the efficacy of this treatment; however, because this represents, to our knowledge, the first use of this technology in human prostate, feasibility and safety were emphasized. In addition, the ability to target the entire prostate gland was not assessed, again for safety considerations. We have not attempted to evaluate the effectiveness of this treatment for eradicating cancer or achieving durable biochemical non-evidence of disease status.”

References

  1. SIMMONS (L.A.M.), AUTIER (P.), ZATURA (F.), BRAECKMAN (J.G.), PELTIER (A.), ROMICS (I.), STENZL (A.), TREURNICHT (K.), WALKER (T.), NIR (D.), MOORE (C.M.), EMBERTON (M.). Detection, localisation and characterisation of prostate cancer by Prostate HistoScanning.. British Journal of Urology International (BJUI). Issue 1 (July). Vol. 110, Page(s): 28-35
  2. WILKINSON (L.S.), COLEMAN (C.), SKIPPAGE (P.), GIVEN-WILSON (R.), THOMAS (V.). Breast HistoScanning: The development of a novel technique to improve tissue characterization during breast ultrasound. European Congress of Radiology (ECR), A.4030, C-0596, 03-07/03/2011.
  3. Hebert Alberto Vargas, MD, Tobias Franiel, MD,Yousef Mazaheri, PhD, Junting Zheng, MS, Chaya Moskowitz, PhD, Kazuma Udo, MD, James Eastham, MD and Hedvig Hricak, MD, PhD, Dr(hc) Diffusion-weighted Endorectal MR Imaging at 3 T for Prostate Cancer: Tumor Detection and Assessment of Aggressiveness. June 2011 Radiology, 259,775-784.
  4. Wendie A. Berg, Kathleen S. Madsen, Kathy Schilling, Marie Tartar, Etta D. Pisano, Linda Hovanessian Larsen, Deepa Narayanan, Al Ozonoff, Joel P. Miller, and Judith E. Kalinyak Breast Cancer: Comparative Effectiveness of Positron Emission Mammography and MR Imaging in Presurgical Planning for the Ipsilateral Breast Radiology January 2011 258:1 59-72.
  5. Anwar R. Padhani, Dow-Mu Koh, and David J. Collins Reviews and Commentary – State of the Art: Whole-Body Diffusion-weighted MR Imaging in Cancer: Current Status and Research Directions Radiology December 2011 261:3 700-718
  6. Eggener S, Salomon G, Scardino PT, De la Rosette J, Polascik TJ, Brewster S. Focal therapy for prostate cancer: possibilities and limitations. Eur Urol 2010;58(1):57–64).
  7. Rajiv Chopra, PhD, Alexandra Colquhoun, MD, Mathieu Burtnyk, PhD, William A. N’djin, PhD, Ilya Kobelevskiy, MSc, Aaron Boyes, BSc, Kashif Siddiqui, MD, Harry Foster, MD, Linda Sugar, MD, Masoom A. Haider, MD, Michael Bronskill, PhD and Laurence Klotz, MD. MR Imaging–controlled Transurethral Ultrasound Therapy for Conformal Treatment of Prostate Tissue: Initial Feasibility in Humans. October 2012 Radiology, 265,303-313.
  8. Black, Peter McL. M.D., Ph.D.; Alexander, Eben III M.D.; Martin, Claudia M.D.; Moriarty, Thomas M.D., Ph.D.; Nabavi, Arya M.D.; Wong, Terence Z. M.D., Ph.D.; Schwartz, Richard B. M.D., Ph.D.; Jolesz, Ferenc M.D.  Craniotomy for Tumor Treatment in an Intraoperative Magnetic Resonance Imaging Unit. Neurosurgery: September 1999 – Volume 45 – Issue 3 – p 423
  9. Medel, Ricky MD,  Monteith, Stephen J. MD, Elias, W. Jeffrey MD, Eames, Matthew PhD, Snell, John PhD, Sheehan, Jason P. MD, PhD, Wintermark, Max MD, MAS, Jolesz, Ferenc A. MD, Kassell, Neal F. MD. Neurosurgery: Magnetic Resonance–Guided Focused Ultrasound Surgery: Part 2: A Review of Current and Future Applications. October 2012 – Volume 71 – Issue 4 – p 755–763
  10. Bruno Quesson PhD, Jacco A. de Zwart PhD, Chrit T.W. Moonen PhD. Magnetic resonance temperature imaging for guidance of thermotherapy. Journal of Magnetic Resonance Imaging, Special Issue: Interventional MRI, Part 1, Volume 12, Issue 4, pages 525–533, October 2000

Writer: Dror Nir, PhD

 

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Author and Curator: Dror Nir, PhD

Radiology congresses are all about imaging in medicine. Interestingly, radiology originates from radiation. It was the discovery of X-ray radiation at the beginning of the 20th century that opened the road to “seeing” the inside of the human body without harming it (at that time that meant cutting into the body).

Radiology meetings are about sharing experience and knowhow on imaging-based management patients. The main topic is always image-interpretation: the bottom line of clinical radiology! This year’s European Congress of Radiology (ECR) dedicated few of its sessions to recent developments in image-interpretation tools. I chose to discuss the one that I consider contributing the most to the future of cancer patients’ management.

In the refresher course dedicated to computer application the discussion was aimed at understanding the question “How do image processing and CAD impact radiological daily practice?” Experts’ reviews gave the audience some background information on the following subjects:

  1. A.     The link between image reconstruction and image analysis.
  2. B.     Semantic web technologies for sharing and reusing imaging-related information
  3. C.     Image processing and CAD: workflow in clinical practice.

I find item A to be a fundamental education item. Not once did I hear a radiologist saying: “I know this is the lesion because it’s different on the image”.  Being aware of the computational concepts behind image rendering, even if it is at a very high level and lacking deep understanding of the computational processes,  will contribute to more balanced interpretations.

Item B is addressing the dream of investigators worldwide. Imagine that we could perform a web search and find educating, curated materials linking visuals and related clinical information, including standardized pathology reporting. We would only need to remember that search engines used certain search methods and agree, worldwide, on the method and language to be used when describing things. Having such tools is a pre-requisite to successful pharmaceutical and bio-tech development.

I find item C strongly linked to A, as all methods for better image interpretation must fit into a workflow. This is a design goal that is not trivial to achieve. To understand what I mean by that, try to think about how you could integrate the following examples in your daily workflow: i.e. what kind of expertise is needed for execution, how much time it will take, do you have the infrastructure?

In the rest of this post, I would like to highlight, through examples that were discussed during ECR 2012, the aspect of improving cancer patients’ clinical assessment by using information fusion to support better image interpretation.

  • Adding up quantitative information from MR spectroscopy (quantifies biochemical property of a target lesion) and Dynamic Contrast Enhanced MR imaging (highlights lesion vasculature).

Image provided by: Dr. Pascal Baltzer, director of mammography at the centre for radiology at Friedrich Schiller University in Jena, Germany

  • Registration of images generated by different imaging modalities (Multi-modal imaging registration).

The following examples: Fig 2 demonstrates registration of a mammography image of a breast lesion to an MRI image of this lesion. Fig3 demonstrates registration of an ultrasound image of a breast lesion scanned by an Automatic Breast Ultrasound (ABUS) system and an MRI image of the same lesion.

Images provided by members of the HAMAM project (an EU, FP7 funded research project: Highly Accurate Breast Cancer Diagnosis through Integration of Biological Knowledge, Novel Imaging Modalities, and Modelling): http://www.hamam-project.org

 

 Multi-modality image registration is usually based on the alignment of image-features apparent in the scanned regions. For ABUS-MRI matching these were: the location of the nipple and the breast thickness; the posterior of the nipple in both modalities; the medial-lateral distance of the nipple to the breast edge on ultrasound; and an approximation of the rib­cage using a cylinder on the MRI. A mean accuracy of 14mm was achieved.

Also from the HAMAM project, registration of ABUS image to a mammography image:

registration of ABUS image to a mammography image, Image provided by members of the HAMAM project (an EU, FP7 funded research project: Highly Accurate Breast Cancer Diagnosis through Integration of Biological Knowledge, Novel Imaging Modalities, and Modelling): http://www.hamam-project.org

  • Automatic segmentation of suspicious regions of interest seen in breast MRI images

Segmentation of suspicious the lesions on the image is the preliminary step in tumor evaluation; e.g. finding its size and location. Since lesions have different signal/image character­istics to the rest of the breast tissue, it gives hope for the development of computerized segmentation techniques. If successful, such techniques bear the promise of enhancing standardization in the reporting of lesions size and location: Very important information for the success of the treatment step.

Roberta Fusco of the National Cancer Institute of Naples Pascal Foundation, Naples/IT suggested the following automatic method for suspi­cious ROI selection within the breast using dynamic-derived information from DCE-MRI data.

 

Automatic segmentation of suspicious ROI in breast MRI images, image provided by Roberta Fusco of the National Cancer Institute of Naples Pascal Foundation, Naples/IT

 

 Her algorithm includes three steps (Figure 2): (i) breast mask extraction by means of automatic intensity threshold estimation (Otsu Thresh-holding) on the par­ametric map obtained through the sum of intensity differences (SOD) calculated pixel by pixel; (ii) hole-filling and leakage repair by means of morphological operators: closing is required to fill the holes on the boundaries of breast mask, filling is required to fill the holes within the breasts, erosion is required to reduce the dilation obtained by the closing operation; (iii) suspicious ROIs extraction: a pixel is assigned to a suspicious ROI if it satisfies two conditions: the maximum of its normalized time-intensity curve should be greater than 0.3 and the maximum signal intensity should be reached before the end of the scan time. The first condition assures that the pixels within the ROI have a significant contrast agent uptake (thus excluding type I and type II curves) and the second condition is required for the time-intensity pattern to be of type IV or V (thus excluding type III curves).

Written by: Dror Nir, PhD

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Author and Curator: Dror Nir, PhD

 

This post is a continuation of

Imaging: seeing or imagining? (Part 1)

https://pharmaceuticalintelligence.com/2012/09/10/imaging-seeing-or-imagining-part-1/

 

That is the question…

Anyone who follows healthcare news, as I do , cannot help being impressed with the number of scientific and non-scientific items that mention the applicability of Magnetic Resonance Imaging (‘MRI’) to medical procedures.

A very important aspect that is worthwhile noting is that the promise MRI bears to improve patients’ screening – pre-clinical diagnosis, better treatment choice, treatment guidance and outcome follow-up – is based on new techniques that enables MRI-based tissue characterisation.

Magnetic resonance imaging (MRI) is an imaging device that relies on the well-known physical phenomena named “Nuclear Magnetic Resonance”. It so happens that, due to its short relaxation time, the 1H isotope (spin ½ nucleus) has a very distinctive response to changes in the surrounding magnetic field. This serves MRI imaging of the human body well as, basically, we are 90% water. The MRI device makes use of strong magnetic fields changing at radio frequency to produce cross-sectional images of organs and internal structures in the body. Because the signal detected by an MRI machine varies depending on the water content and local magnetic properties of a particular area of the body, different tissues or substances can be distinguished from one another in the scan’s resulting image.

MRI scan of a breast lesion (Source Radiology.com)

The main advantages of MRI in comparison to X-ray-based devices such as CT scanners and mammography systems are that the energy it uses is non-ionizing and it can differentiate soft tissues very well based on differences in their water content.

In the last decade, the basic imaging capabilities of MRI have been augmented for the purpose of cancer patient management, by using magnetically active materials (called contrast agents) and adding functional measurements such as tissue temperature to show internal structures or abnormalities more clearly.

In order to increase the specificity and sensitivity of MRI imaging in cancer detection, various imaging strategies have been developed. The most discussed in MRI related literature are:

  • T2 weighted imaging: The measured response of the 1H isotope in a resolution cell of a T2-weighted image is related to the extent of random tumbling and the rotational motion of the water molecules within that resolution cell. The faster the rotation of the water molecule, the higher the measured value of the T2 weighted response in that resolution cell. For example, prostate cancer is characterized by a low T2 response relative to the values typical to normal prostatic tissue [5].

T2 MRI pelvis with Endo Rectal Coil ( DATA of Dr. Lance Mynders, MAYO Clinic)

  • Dynamic Contrast Enhanced (DCE) MRI involves a series of rapid MRI scans in the presence of a contrast agent. In the case of scanning the prostate, the most commonly used material is gadolinium [4].

Axial MRI Lava DCE with Endo Rectal ( DATA of Dr. Lance Mynders, MAYO Clinic)

  • Diffusion weighted (DW) imaging: Provides an image intensity that is related to the microscopic motion of water molecules [5].

DW image of the left parietal glioblastoma multiforme (WHO grade IV) in a 59-year-old woman, Al-Okaili R N et al. Radiographics 2006;26:S173-S189

  • Multifunctional MRI: MRI image overlaid with combined information from T2-weighted scans, dynamic contrast-enhancement (DCE), and diffusion weighting (DW) [5].
  • Blood oxygen level-dependent (BOLD) MRI: Assessing tissue oxygenation. Tumors are characterized by a higher density of micro blood vessels. The images that are acquired follow changes in the concentration of paramagnetic deoxyhaemoglobin [5].

In the last couple of years, medical opinion leaders are offering to use MRI to solve almost every weakness of the cancer patients’ pathway. Such proposals are not always supported by any evidence of feasibility. For example, a couple of weeks ago, the British Medical Journal published a study [1] concluding that women carrying a mutation in the BRCA1 or BRCA2 genes who have undergone a mammogram or chest x-ray before the age of 30 are more likely to develop breast cancer than those who carry the gene mutation but who have not been exposed to mammography. What is published over the internet and media to patients and lay medical practitioners is: “The results of this study support the use of non-ionising radiation imaging techniques (such as magnetic resonance imaging) as the main tool for surveillance in young women with BRCA1/2 mutations.”.

Why is ultrasound not mentioned as a potential “non-ionising radiation imaging technique”?

Another illustration is the following advert:

Advert in favour of MRI termal imaging of breast

An MRI scan takes between 30 to 45 minutes to perform (not including the time of waiting for the interpretation by the radiologist). It requires the support of around 4 well-trained team members. It costs between $400 and $3500 (depending on the scan).

The important question, therefore, is: Are there, in the USA, enough MRI  systems to meet the demand of 40 million scans a year addressing women with radiographically dense  breasts? Toda there are approximately 10,000 MRI systems in the USA. Only a small percentage (~2%) of the examinations are related to breast cancer. A

A rough calculation reveals that around 10,000 additional MRI centers would need to be financed and operated to meet that demand alone.

References

  1. Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (GENE-RAD-RISK), BMJ 2012; 345 doi: 10.1136/bmj.e5660 (Published 6 September 2012), Cite this as: BMJ 2012;345:e5660 – http://www.bmj.com/content/345/bmj.e5660
  1. http://www.auntminnieeurope.com/index.aspx?sec=sup&sub=wom&pag=dis&itemId=607075
  1. Ahmed HU, Kirkham A, Arya M, Illing R, Freeman A, Allen C, Emberton M. Is it time to consider a role for MRI before prostate biopsy? Nat Rev Clin Oncol. 2009;6(4):197-206.
  1. Puech P, Potiron E, Lemaitre L, Leroy X, Haber GP, Crouzet S, Kamoi K, Villers A. Dynamic contrast-enhanced-magnetic resonance imaging evaluation of intraprostatic prostate cancer: correlation with radical prostatectomy specimens. Urology. 2009;74(5):1094-9.
  1. Advanced MR Imaging Techniques in the Diagnosis of Intraaxial Brain Tumors in Adults, Al-Okaili R N et al. Radiographics 2006;26:S173-S189 ,

http://radiographics.rsna.org/content/26/suppl_1/S173.full

  1. Ahmed HU. The Index Lesion and the Origin of Prostate Cancer. N Engl J Med. 2009 Oct; 361(17): 1704-6

Writer: Dror Nir, PhD.

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