Two-drug combination destroys precancerous colon polyps....

A team of scientists at The University of Texas M. D. Anderson Cancer Center lead by Dr. Xiangwei Wu have come up with interesting finding i.e.,  a two-drug combination destroys precancerous colon polyps with no effect on normal tissue, opening a new potential avenue for chemoprevention of colon cancer. 

The regimen, tested so far in mouse models and on human colon cancer tissue in the lab, appears to address a problem with chemopreventive drugs - they must be taken continuously long term to be effective, exposing patients to possible side effects. 

The team found that a combination of Vitamin A acetate (RAc see  structure; source: Wikipedia) and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), kills precancerous polyps and inhibits tumor growth in mice that have deficiencies in a tumor-suppressor gene. That gene, adenomatous polyposis coli (APC) and its downstream signaling molecules, are mutated or deficient in 80 percent of all human colon cancer.  

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent endogenous activator of the cell death pathway and functions by activating the cell surface death receptors 4 and 5 (DR4 and DR5). TRAIL is nontoxic in vivo and preferentially kills neoplastically transformed cells over normal cells by an undefined mechanism.

Interestingly, early experiments with APC-deficient mice showed that the two drugs combined or separately did not harm normal colon epithelial cells. Separately, they showed no effect on premalignant polyps called adenomas.

RAc and TRAIL together killed adenoma cells, causing programmed cell suicide know as apoptosis. RAc, researchers found, sensitizes polyp cells to TRAIL.

The scientists painstakingly tracked the molecular cascade caused by APC deficiencies, and found that insufficient APC sensitizes cells to TRAIL and RAc by suppressing a protein that blocks TRAIL.

APC-deficient mice were treated with 15 cycles of the RAc/TRAIL combination over six weeks. Others received either RAc or TRAIL and a control group received nothing. One month later, control mice and those treated with one of the drugs averaged between 35 and 42 polyps, while those receiving the combination averaged 10.

To test the combination’s potential as short-term therapy, APC-deficient mice were treated with two cycles of the combination in one week, causing a 69 percent polyp reduction two weeks later. A 10-fold increase in dose left treated mice with only 10 percent of the polyps found in controls.

A longer term test of relative survival using five treatments over four months improved survival from 186 days for controls to beyond 213 days for treated mice, with five of seven treated mice living more than eight months. Next, the researchers treated biopsy samples of normal tissue and tumor regions from patients with familial adenomatous polyposis – an inherited condition that inevitably leads to colon cancer if the colon is not removed. Treatment of normal tissue caused little cell death, while 57 percent of polyp cells were killed via apoptosis.

Targeted therapies today aim at blocking some aspect of the tumor that drives its growth, Wu said, whereas RAc and TRAIL together kill precancerous polyps outright. Since APC is deficient or mutated in other types of cancer, the combination therapy could become a more general drug.

Before human clinical trials can be considered, the team will conduct additional research to understand potential side effects and also will try to develop an injectable version of the combination, which is administered intravenously now..

Ref : http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08871.html

Self-Poisoning of Mycobacterium tuberculosis by targeting GlgE in an a-glucan pathway...

In the past few years, extremely drug resistant strains of TB have arisen that can’t be eliminated by any drugs, so new strategies for attacking TB are urgently needed.

Now, researchers at Albert Einstein College of Medicine of Yeshiva University have found two novel ways of killing the bacteria that cause tuberculosis.

In searching for a new Achilles’ heel for M. tuberculosis, Dr. Jacobs and colleagues focused on an enzyme called GlgE. Previous research had suggested  that GlgE might be essential for the growth of TB bacteria.        (building polysaccharides) GlgE would also be an excellent drug target because there are no enzymes similar to it in humans or in the bacteria of the human gut.

Using genetic and biochemical approaches, William Jacobs and colleagues identified four enzymes involved in a pathway that converts a naturally-occurring sugar compound into polysaccharides called alpha-glucans. The scientists found that inactivating one of these enzymes, TreS, was not lethal to the bacteria, indicating that this pathway is not required for growth. 

However, inactivating GlgE was lethal, causing the buildup of toxic levels of the enzyme's sugar substrate, maltose-1-phosphate. In addition, the scientists found that the combined inactivation of TreS and an enzyme for an alternate alpha-glucan biosynthetic pathway was lethal, highlighting the important roles of alpha-glucan's in M. tuberculosis growth.

Sure enough, when the researchers inhibited GlgE, the bacteria underwent "suicidal self-poisoning": a sugar called maltose 1-phosphate accumulated to toxic levels that damaged bacterial DNA, causing the death of TB bacteria grown in Petri dishes as well as in infected mice.

The researchers discovered a second way of killing TB after observing a crucial connection between their novel alpha glucan pathway and a second pathway that also synthesizes alpha glucans. 

When the researchers knocked out one of the other enzymes in their novel pathway, the pathway's shutdown didn't kill the bacteria; similarly, inactivating an enzyme called Rv3032 in the second alpha glucan pathway failed to kill the microbes. But inactivating both of those enzymes caused what the researchers term synthetic lethality: two inactivations that separately were nonlethal but together cause bacterial death. 

Though the biological role of the GlgE pathway remains to be elucidated, GlgE and the alpha-glucan pathways more generally, are possible drug targets that can now be tested in in vivo models of tuberculosis infection....

"The bacteria that cause TB need to synthesize alpha glucans," notes Dr. Jacobs. "And from the bacterial point of view, you can't knock out both of these alpha glucan pathways simultaneously or you're dead. So if we were to make drugs against GlgE and Rv3032, the combination would be extremely potent. And since TB bacteria need both of those alpha glucan pathways to live, it's very unlikely that this combination therapy would leave behind surviving bacteria that could develop into resistant strains."

Ref :  http://www.nature.com/nchembio/journal/vaop/ncurrent/pdf/nchembio.340.pdf

FDA approves Graceway Pharmaceuticals' NDA for Zyclara

We know that Imiquimod (structure - source -Drug Bank) is an   immune response modifier that acts as a toll-like receptor 7 agonist. Imiquimod is commonly used topically to treat warts on the skin of the genital and anal areas. Imiquimod does not cure warts, and new warts may appear during treatment. Imiquimod does not fight the viruses that cause warts directly, however, it does help to relieve and control wart production.

Graceway® Pharmaceuticals announced recently  that, FDA has approved the New Drug Application (NDA) for Zyclara™, determining it to be safe and effective for the treatment of clinically typical, visible or palpable actinic keratoses (AK).   

The new treatment can be used on large areas of skin, including the full face or balding scalp on a convenient, 6-week dosing cycle.Zyclara shares the same active ingredient as Aldara® (imiquimod) Cream, 5% and while both topicals are FDA-approved for the treatment of AK, there are notable differences between the two.  

Zyclara is indicated for daily use on an accelerated 6-week dosing cycle comprised of two weeks of daily treatment with Zyclara, two weeks of non-treatment, followed by two weeks of daily treatment with Zyclara. Aldara is not approved for daily use and its approved dosing regimen is for a full 16 weeks.  Additionally, Zyclara is indicated for use on larger areas of skin, the full face or balding scalp, while Aldara is restricted to a 25 cm2 area of skin. 

"Because AKs are pre-cancerous and can develop on skin frequently exposed to the sun, such as the face or balding scalp, an effective treatment that can be used on large areas of skin is beneficial," said Darrell Rigel, M.D., clinical professor of dermatology, New York University Medical Center. ....

Ref : http://www.zyclaracream.com/

Mecamylamine may help to treat diabetic macular edema ......

We know that mecamylamine (see structure) has been used as a  ganglionic blocker in treating hypertension, but, like most ganglionic blockers, is more often used now as a research tool. It is also sometimes used as an anti-addictive drug to help people stop smoking tobacco, and is now more widely used for this application than it is for lowering blood pressure. This effect is thought to be due to it blocking α3β4 nicotinic receptors in the brain.

Now researchers from the Wilmer Eye Institute of Johns Hopkins University School of Medicine in Maryland have come up with an interesting finding from an early-stage human clinical trials. i.e.,  the drug  'mecamylamine'  was safe and had biological effects in a type of diabetic eye disease, and may offer researchers a new approach to prevent and treat diabetic macular edema. 

Diabetic macular edema is a complication of a specific region of the retina in the eye, called the macula, that develops when small blood vessels become leaky such that fluid accumulates. Without treatment, diabetic macular edema can cause vision impairment, blurriness, or blindness.

As per the claim by the researcers,  approximately 40% of the participants showed significant improvement in overall vision and/or the thickness of the retina. The treatment also showed biological effects in the retina indicating that the drug was able to gain access to the retinal vessels.

"The safety and early signals of treatment effect arising from this study may create a strong interest in the development of multiple treatment options that are affordable and can be self-administered, helping to ease the burden of healthcare delivery and compliance," said Barbara Araneo, Director of Complications Research for JDRF. ...

Ref : http://www.jdrf.org/index.cfm?fuseaction=home.viewPage&page_id=9065027A-1321-C844-137596CDA72C825B 

Methionine Aminopeptidases from Mycobacterium tuberculosis as Novel Antimycobacterial Targets ..

Suspecting that a particular protein in tuberculosis was likely to be vital to the bacteria's survival, Johns Hopkins scientists screened 175,000 small chemical compounds and identified a potent class of compounds that selectively slows down this protein's activity and, in a test tube, blocks TB growth, demonstrating that the protein is indeed a vulnerable target.

 

This class of chemical compounds attacks TB by inhibiting methionine aminopeptidase (MetAP), an essential enzyme found in organisms ranging from bacteria to humans, and that clearly has been conserved throughout evolution because of its important task of ensuring the proper manufacture of proteins.

Methionine aminopeptidase (MetAP) is a metalloprotease that removes the N-terminal methionine during protein synthesis. To assess the importance of the two MetAPs in Mycobacterium tuberculosis, researchers overexpressed and purified each of the MetAPs to near homogeneity and showed that both were active as MetAP enzymes in vitro. 

 

Researchers screened a library of 175,000 compounds against MtMetAP1c and identified 2,3-dichloro-1,4-naphthoquinone class of compounds as inhibitors of both MtMetAPs. It was found that the MtMetAP inhibitors were active against replicating and aged nongrowing M. tuberculosis. Overexpression of either MtMetAP1a or MtMetAP1c in M. tuberculosis conferred resistance of bacterial cells to the inhibitors. As per the claim by the researchers, knockdown of MtMetAP1a, but not MtMetAP1c, resulted in decreased viability of M. tuberculosis and they conclude  that MtMetAP1a is a promising target for developing antituberculosis agents.

 

The scientists cautioned that although the MetAP inhibitors prevent TB growth in test tubes, they have a long way to go before being declared safe and effective to treat TB patients...

 

"Judging from potency, a MetAP inhibibitor alone probably won't wipe out TB," Liu says. "TB is so hard to treat that the standard therapy involves a cocktail of multiple drugs; no single compound is powerful enough. Our hope is that someday an inhibitor of MetAP will become a new component to enhance the existing therapy."

Ref : Jun O. Liu et.al., Chemistry & Biology, Volume 17, Issue 1, 29 January 2010, Pages 86-97

Clinical Data completes NDA submission for vilazodone.......

         Vilazodone (structure) is an antidepressant and anxiolytic of  the piperazine chemical class.

Clinical Data, Inc.   recently announced that the Company has submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for vilazodone for the treatment of major depressive disorder (MDD). Vilazodone is a dual-acting potent and selective serotonin reuptake inhibitor and a 5-HT_1A receptor partial agonist. The Company expects that the NDA submission, if accepted, will be subject to a standard review. 

This is a major milestone in the development of vilazodone and, if approved, its dual mechanism of action and safety profile will offer a new alternative for patients suffering from depression,” said Carol R. Reed, M.D..more...

Gemcitabine and cisplatin a promising combination for endometrial cancer...

In continuation of my update on cis-platin and its importance, I find this  info interesting to share with...

Gemcitabine (see structure) and cisplatin in combination have been investigated extensively in other disease sites, and synergism of the two agents has been confirmed in cell lines of human endometrial, ovarian, colon, lung and squamous cell head and neck carcinoma

Now researchers from The University of Texas M. D. Anderson Cancer Center , lead by Dr.Jubilee Brown, report from a small study of women with advanced or recurrent endometrial cancer, that gemcitabine and cisplatin, when used in combination, produced a response rate in fifty percent of patients.

The Phase II study of 20 patients found that the combination of gemcitabine and cisplatin, two drugs currently used to treat other types of cancer, limited the disease's progression, increasing progression-free survival while maintaining tolerable toxicity levels. It is believed that when administered together, gemcitabine helps overcome cell resistance to cisplatin, throwing tumor cells a potent one-two punch.


Findings demonstrated a 50 percent overall response rate, or improvement in disease. Additionally, the clinical benefit of the two-drug combination was 80 percent, as 16 of the 20 women experienced either an improvement or stabilization of disease. All side effects resulting from the therapy were manageable. Lead researcher, Dr. Brown concluded  that results from the study warrant investigation of the chemotherapy combination in a larger, definitive trial at multiple institutions.....

Ref :  Dr. Jubilee Brown, http://www.mdanderson.org/

New study finds green tea extract may prevent Alzheimer's disease and dementia

In continuation of my update on green tea benefits......

New study finds green tea extract may prevent Alzheimer's disease and dementia

Salsalate may be useful for the treatment of patients with type 2 diabetes .....

We know that Salsalate (see structure; source Drugs.com)  is a  non-steroidal anti-inflammatory drug (NSAID) belonging to salicylates. It is used in the treatment of Osteo Arthritis and  Rheumatoid Arthritis. 

Now researchers from Harvard Medical School, lead by Dr. Allison Goldfine, have come up with interesting finding, i.e., Salsalate may be useful for the treatment of patients with type 2 diabetes as well. In a three-month trial of people with type 2 diabetes ,  those who took the drug showed significantly improved blood glucose levels. 

Starting off, the patients all had levels of hemoglobin A1C (a standard measurement that reflects blood sugar levels over several months) in the range of 7.0 to 9.5%. A significant number of those who took salsalate saw this number drop by 0.5%, a result that is in the range of several recently released diabetes therapeutics. Other tests related to glucose levels also showed substantial improvement.  

Overall the drug appeared to be safe and to be tolerated well by patients. The study included 108 individuals, aged from 18 to 75 years, at 17 clinical sites around the United States. Patients were randomly divided into four; three groups were each given differing amounts of salsalate in three daily doses, while the fourth received placebos. All patients continued with their current regimes for managing diabetes.

Though these preliminary findings  suggests  that,   salsalate may provide an effective, safe and inexpensive new avenue for diabetes treatment, however the researchers  want to complete the ongoing  additional studies so that they can further substantiate their claim........

Ref : March 16 in the Annals of Internal Medicine

Study provides better understanding of how mosquitoes find a host......

In continuation of my update on on developments in mosquito repellents ......

The potentially deadly yellow-fever-transmitting Aedes aegypti mosquito detects the specific chemical structure of a compound called octenol as one way to find a mammalian host for a blood meal, Agricultural Research Service (ARS) scientists report".......

Ref : http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0007032....