Even though the main objective of tumor surgery is to remove tumors as much as possible without disturbing the adjacent normal tissues, the task is very challenging in the operating room as neoplastic tissue is hard to distinguish from the adjacent healthy tissue. Thus, the portion of tumor still remained in the body after surgery causes recurrence, treatment failure, and poor outcome.

Surgery is an important treatment modality for brain tumors. Therefore, distinguishing normal tissue from tumor is extremely important for brain tumor surgery owing to the risk of damaging functional brain structures. Removal of healthy tissue can cause neurologic problems, but leaving tumor tissue behind can allow the cancer to grow and spread again. This is a major problem with glioblastoma multiforme (GBM), the most common form of malignant brain tumor in adults. Glioblastoma tumors grow quickly and are difficult to treat. The tumors infiltrate normal brain tissue and can’t be easily singled out. Therefore, tools designed to safely maximize the removal of tumor tissue are warranted. So far, experimental attempts to tell the difference between tumors and normal tissue during surgery have had limited success until recently, a new study by Ji et al. (2013) reported successful separation of  tumor-infiltrated brain tissue from surrounding healthy tissue in mice using stimulated Raman scattering (SRS) microscopy. Ji and colleagues provided evidence that SRS microscopy can be used to delineate tumor tissue in a human GBM xenograft mouse model, both ex vivo and in vivo, and in human brain tumor surgical specimens.


Raman spectroscopy is a technique to study the interactions (vibrational, rotational, and other low-frequency modes) between matter and radiation in a system. It is named after the Indian noble laureate Dr. C.V. Raman (1930) who described the effect of light impinges upon a molecule and its interactions with the electron cloud and the bonds of that molecule. Chemical bonds in molecules have their own sets of vibration frequencies, and produce unique patterns of scattered light called Raman spectra. These spectra can be used as fingerprints to identify and differentiate different molecules in a complex environment. Developed on the concept of Raman spectroscopy, SRS is now emerging as an imaging technique to image biological tissues based on the intrinsic vibrational spectroscopy of their molecular components such as lipids, proteins, and DNA. Being free from the drawbacks of the dye-based methods, this label-free imaging technique exhibits high chemical selectivity enabling its use in complex biological applications including brain imaging.

To this end, Ji and colleagues used SRS microscopy to the problem of distinguishing protein-rich glioblastomas from more lipid-rich surrounding tissue and showed that it can be used to detect glioma ex vivo in human GBM xenograft mice, with results that correlated with the interpretation of hematoxylin and eosin (H&E)–stained slides by a surgical pathologist. Most importantly, this study demonstrated that SRS microscopy can detect extensive tumor infiltration in regions that appear grossly normal under standard bright-field conditions. This study suggests that SRS holds promise for improving the accuracy and effectiveness of cancer surgery. However, several challenges remain to be overcome including making a handheld surgical device with motion correction to acquire images from within a surgical cavity.


Ji M, Orringer DA, Freudiger CW, Ramkissoon S, Liu X, Lau D, et al. Rapid, label-free detection of brain tumors with stimulated Raman scattering microscopy. Sci Transl Med. 2013;5:201ra119.




One of the primary roles of the immune system is the specific identification and elimination of tumor cells on the basis of their expression of tumor-specific antigens or molecules induced by cellular stress. This process is referred to as tumor immune surveillance. In this process the immune system recognizes malignant and/or pre-malignant cells and removes them. However, tumor cells do escape from tumor immune surveillance, and therefore, therapies targeted to enhance antitumor immunity is currently in development.

Blockade of immune checkpoints  is the most promising approach to activate therapeutic antitumour immunity. Immune checkpoints refer to a group of inhibitory pathways connected into the immune system that are important for maintaining self-tolerance. In peripheral tissues immune surveillance also modulates the duration and amplitude of physiological immune responses in order to minimize collateral tissue damage. Studies have suggested that tumor cells adopt many immune-checkpoint pathways as a major mechanism of immune resistance. Immune checkpoint receptors cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4, also known as CD152) and programmed death 1 (PD-1) receptor appear to play important roles in antitumor immunity and have been most actively studied in the context of clinical cancer immunotherapy.

monoclonal3CTLA-4 is expressed on T cells and down modulates the amplitude of T cell activation. Several preclinical studies demonstrated significant antitumor responses following blockade of CTL4-A with limited immune toxicities. This led to the development of two fully humanized  CTLA-4 antibodies ipilimumab and tremelimumab. In clinical trials, ipilimumab demonstrated survival benefits for patients with metastatic melanoma, and was approved by the US Food and Drug Administration (FDA) for the treatment of advanced melanoma in 2010.

On the other hand, PD-1limits T cell effector functions within tissues. Tumor  cells block antitumor immune responses in the tumor microenvironment by upregulating ligands (PDL1 and PDL2) for PD1. Several studies detected increased PD1 expression by tumor infiltrating lymphocytes and the increased expression of PD1 ligands in melanoma, ovarian, lung, renal-cell cancers and in lymphomas. This provided an important rationale to target PD1 in order to enhance antitumor immunity. The fully human antibody nivolumab was found to produce durable objective responses in patients with melanoma, renal-cell cancer, and non-small-cell lung cancer.

Even though individual blocking of CTLA-4 and PD-1 have shown substantial clinical antitumor activity, studies suggest that blocking a single inhibitory receptor only leads to up-regulation of the unblocked pathway. Therefore, in order  to enhance antitumor immunity within the tumor microenvironment it appears to require simultaneous blockade of multiple negative co-stimulatory receptors. In preclinical studies, concurrent inhibition of CTLA-4 and PD-1 resulted in more pronounced antitumor activity than blockade of either pathway alone. On the basis of these observations, a phase I study was conducted to investigate the safety and efficacy of combined inhibition of CTLA-4 and PD-1in advanced melanoma patients and published recently in The New England Journal of Medicine (July 11, 2013). In their study, Wolchok and collagues (2013) treated 53 patients concurrently, and 33 patients sequentially with nivolumab and ipilimumab. Rapid responses were observed in concurrent-regimen cohorts as compared with sequential-regimen cohorts. The objective response rate in the concurrent-regimen cohorts was 40% along with 53% patients exhibited tumor regression of 80% or more. The objective response rate in the sequenced-regimen cohorts was 20% and 13% patients had tumor regression of 80% or more. In both groups, treatment related adverse events were managed with the use of immunosuppressants.

Collectively this study suggested that combined blockade of CTLA-4 and PD-1 would be more effective to enhance antitumor immunity compared to single inhibition of either CTLA-4 or PD-1.


1.  Swann, J.B. and M.J. Smyth, Immune surveillance of tumors. J Clin Invest, 2007. 117(5): p. 1137-46.

2.   Pardoll, D.M., The blockade of immune checkpoints in cancer immunotherapy. Nat Rev Cancer, 2012. 12(4): p. 252-64.

3.   Topalian, S.L., et al., Safety, activity, and immune correlates of anti-PD-1 antibody in cancer. N Engl J Med, 2012. 366(26): p. 2443-54.

4.   Wolchok, J.D., et al., Nivolumab plus ipilimumab in advanced melanoma. N Engl J Med, 2013. 369(2): p. 122-33.


The human gut harbors approximately one thousand different bacterial species (intestinal microbiota). Intestinal microbiota number 100 trillion cells; over 90 percent of the cells in the body are bacteria. The composition of each person’s microbiome — the body’s bacterial make-up — is very different, due to the types of bacteria people ingest in their early lives, as well as the effects of diet and lifestyle.

Several studies implicated intestinal bacteria in various cancers. Gram-negative Helicobacter species were found to be associated with liver cancer, colon cancer, and breast cancer. A recent study published in the peer reviewed journal Nature by Yoshimoto et al. (2013) reported that gut bacteria of obese mice unleash high levels of an acid that promotes liver cancer. In rodents, intestinal bacteria influence obesity, intestinal inflammation and certain types of epithelial cancers. However, in human, little is known about the identity of the bacterial species that promote the growth or protect the body from cancer. Therefore, studies are warranted to determine whether differences in peoples’ microbiomes affect their risk for cancer, and whether changing the bacteria can reduce this risk. A clinical trial at the National Cancer Institute (NCI) is currently evaluating the relationship between intestinal bacteria and breast cancer risk (Clinical number: NCT01461070).

intestinal  bacteria

For the first time, a recent study by Yamamoto et al. (2013) demonstrated a relationship between intestinal microbiota and onset of lymphoma (a type of blood cancer of B or T lymphocytes). Yamamoto and colleagues studied mice with ataxia-telangiectasia (A-T), a genetic disease that in humans and mice is associated with a high rate of B-cell lymphoma. These investigators discovered that of mice with A-T, those with certain microbial species lived much longer than those with other bacteria before developing lymphoma, and had less of the gene damage (genotoxicity) that causes lymphoma. A high-throughput sequence analysis of rRNA genes identified the bacteria Lactobacillus johnsonnii in abundance in more cancer-resistant mouse colonies compared to cancer-prone mouse colonies.This study by Yamamoto et al. also created a detailed catalog of bacteria types with promoting or protective effects on genotoxicity (a chemical or other agent that damages cellular DNA, resulting in mutations or cancer) and lymphoma, which could be used in the future to formulate combination therapies that kill the bacteria that promote cancer (such as antibiotics) and increase the presence of the bacteria that protect from cancer (like probiotics).


1.   Ward, J.M., et al., Chronic active hepatitis in mice caused by Helicobacter hepaticus. Am J Pathol, 1994. 145(4): p. 959-68.

2.   Yoshimoto, S., et al., Obesity-induced gut microbial metabolite promotes liver cancer through senescence secretome. Nature, 2013. 499(7456): p. 97-101.

3.   Yamamoto, M.L., et al., Intestinal Bacteria Modify Lymphoma Incidence and Latency by Affecting Systemic Inflammatory State, Oxidative Stress, and Leukocyte Genotoxicity. Cancer Res, 2013. 73(14): p. 4222-4232.




Over expression of estrogen receptor (ER) has been implicated in over 70% of breast cancers. Thus therapy targeting ER directly or indirectly is the most important modality in the two-thirds of patients with an ER-positive early breast cancer. The mainstay of endocrine therapy targeting ER in postmenopausal women that are currently available includes selective ER modulators such as tamoxifen and raloxifene, and the ‘third-generation’ aromatase inhibitors (AIs), anastrozole, exemestane and letrozole (click here for more information:

Even though endocrine therapy is the most effective treatment for ER-positive metastatic breast cancer, its effectiveness is limited by high rates of innate (intrinsic) and acquired resistance during treatment. Only about 30% of patients with metastatic disease have objective regression of tumor with initial endocrine treatment, while another 20% have prolonged stable disease.Estrogen_Receptor_Positive_Breast_Cancer-3

Even though mutations of ER are rarely reported, other mechanisms such as ER-phosphorylation has been implicated in resistance to tamoxifen.  In addition, several clinical studies suggested potential mechanisms of resistance to endocrine therapy. Some of the mechanisms implicated include loss of ER, loss of progesterone receptor (PR), upregulation of HER-2, and response to sequential endocrine therapy.

Using a high throughput screening, a recent study by Stebbing et al.  identified a regulator of ER-α, Lemur tyrosine kinase 3 (LMTK3), and noted that LMTK3 gene amplification in both circulating free DNA and primary tumors are predictive of resistance to tamoxifen. Using an orthotopic breast cancer model with tamoxifen-resistant breast cancer cells BT474 that overexpress LMTK3, Stebbing and his colleagues noted that tamoxifen treatment along with LMTK3 knock-down resulted in significant inhibition of tumor growth compared to untreated control mice. To evaluate the clinical relevance of this observation, levels of LMTK3 were determined by immunohistochemistry in tumor samples from ER-positive breast cancer patients treated with endocrine therapy. High levels of LMTK3 were observed in non-responders compared to responders suggesting the association of LMTK3 in limiting efficacy of endocrine therapy. To identify genes and signaling pathways affected by LMTK3, a genome-wide gene expression analysis was performed using BT747 cells. One gene whose expression was found to be significantly regulated by LMTK3 was HSPB8 (heat shock 22kD protein 8). Both overexpression of HSPB8 in breast cancer and potential involvement in tamoxifen resistance have been reported by other studies. Taken together, these results suggests that LMTK3 can contribute to tamoxifen resistance.

ER targeted therapy has improved the quality of life and survival of millions of women around the world, however, resistance to therapy continues to be a major problem. Identification of the role LMTK3 in resistance would facilitate to formulate strategies to overcome this problem.

Further Reading:

Ali S, Coombes RC. Endocrine-responsive breast cancer and strategies for combating resistance. Nat Rev Cancer. 2002;2(2):101-112.

Osborne CK, Schiff R. Mechanisms of endocrine resistance in breast cancer. Annu Rev Med. 2011;62:233-247.

Stebbing J, Filipovic A, Lit LC, et al. LMTK3 is implicated in endocrine resistance via multiple signaling pathways. Oncogene. 2013;32(28):3371-3380.