Geron plans to advance clinical program for spinal cord injury

In my earlier blog (Euphoria over Stem Cell Therapy.....) did mentioned that, there are many companies which falsely claimed that they have got technology (stem cell treatment) to treat spinal cord injury. But an established company like Geron, has plan to advance clinical development of its human embryonic stem cell (hESC)-based product, GRNOPC1, for the treatment of spinal cord injury. The plan is expected to enable Geron to re-initiate the Phase I clinical trial of GRNOPC1 in patients with complete thoracic spinal cord injury and to support future expansion of the trial to patients with cervical injuries.

I read earlier about the preclinical studies of GRNOPC1 and the company claimed that it is developing GRNOPC1 for spinal cord injury, but is also exploring application for other neurological diseases, including multiple sclerosis, stroke and Alzheimer disease really interesting to see the results.

As I had an opportunity to talk and work (contract research) with Geron [known for its first-in-class biopharmaceuticals (especially "antisense drugs" from oligonucleotides) for the treatment of cancer and chronic degenerative diseases] company, I know its credentials and am really excited to see some interesting out come from their advance clinical program. All the best....

Ref : http://www.geron.com/media/pressview.aspx?id=1195

Phase III clinical study of trabedersen....

In my earlier blogs, did mention about the "antisense drugs belonging to (Geron corporation) phosphorothioate antisense oligonucleotides" . I did also mention that there are many companies working with this field (antisense). Yes now Antisense Pharma GmbH has announced that, it has received the approval by Health Canada for its pivotal Phase III clinical trial SAPPHIRE in patients with recurrent or refractory anaplastic astrocytoma. The SAPPHIRE study is a randomized, active-controlled, clinical trial designed to confirm the efficacy and safety of the investigational drug trabedersen (AP 12009 a phosphorothioate antisense oligonucleotide), observed in previous clinical studies. Trabedersen is being investigated as monotherapy compared to current standard therapy with temozolomide (alternatively BCNU (carmustine)). The results of a previous randomized, active-controlled Phase IIb study show that the novel, targeted therapy holds significant promise. Hope in the days to come, more drugs from this class of compounds...

Ref :http://www.anticancer.de/index.php?id=38.

I found this video, interesting (mode of action of trabedersen)

Telomerase & Telomerase inhibition.......

When I read about the Nobel prize in Medicine, was really excited because the scientists who discovered the enzyme telomerase got the Nobel prize for the year 2009 and the reason for this is simple and obvious....

When I was working with my previous company (Innovasynth Technologies Limited, Khopoli), I had opportunity to learn lots of things (from Dr. Sergei Gryaznov of Geron Corporation) about the drugs with Telomerase inhibition activity. As for as my knowledge goes, there are many companies working on these class of compounds and hope in the days to come there will be many drugs from this class of compounds and antisense drugs.

About Telomerase :

Telomerase, is an enzyme that adds specific DNA sequence repeats to the 3' end of DNA strands in the telomerase regions, which are found at the ends of eukaryotic chromosomes. The telomeres contain condensed DNA material, giving stability to the chromosomes. The enzyme is a reverse transcriptase that carries its own RNA molecule. Though the existence of a compensatory shortening of telomere (telomerase) mechanism, was first predicted by Soviet biologist Alexey Olovnikov (1973), who also suggested the Telomere hypothesis of ageing and the Telomere relations to cancer. Carol Greider and Elizabeth Blackburn in 1985, discovered telomerase together with Jack Szostak. Greider and Blackburn have been awarded the Nobel Prize in Physiology or Medicine. Congrats for this remarkable achievement.


Telomerase inhibitors :

To safeguard against cancer, adult cells keep track of how many times that they have multiplied, and once they have reached a pre-set limit — often around 80 divisions — they die. Telomerase interferes with this record keeping. So if one can find a drug or gene therapy that interferes with telomerase, it could fight the unchecked growth of cancer cells. As per the claim by lead researcher (Mark Muller), 90% all cancer cells are telomerase rich. Geron corporation, is developing modified DNA molecule (for which Innovasynth, has tie up with Geron to provide the intermediate amidites). The oligonucleotides, which target the template region, or active site, of telomerase. Geron's work has focused oligonucleotides (GRN163 and GRN163L,) and as per the claim by the company, both of them have demonstrated highly potent telomerase inhibitory activity at very low concentrations in biochemical assays, various cellular systems and animal studies. Interestingly these compounds are direct enzyme inhibitors, not antisense compounds and smaller than typical antisense compounds or other oligonucleotide drug candidates. Both compounds use a special thiophosphoramidate chemical backbone and the company is hopeful of convincing clinical trial results. All the best...

Ref : 1. http://nobelprize.org/nobel_prizes/medicine/laureates/2009/press.html
2. http://www.geron.com/products/productinformation/cancerdrug.aspx

NDA of Cladribine as a drug for Multiple Sclerosis !

When I was working with Innovasynth Technologies, Khopoli, I worked in the field of "antisense drugs" and as the company has tie up with many MNCs (working with these class of compounds) I had many times interacted with Serono, Pharmaceuticals (US) for some of the intermediates (oligonucleotides). When I read this article, I am happy there are many drugs still to be established as antisense drugs and more over this NDA (new drug application) is something to cherish.

We know that 2-chlorodeoxyadenosine, Cladribine (Leustatin) is drug used to treat hairy cell leukemia (leukemic reticuloendotheliosis).

As a purine analog, it is a synthetic anticancer agent that also suppresses the immune system. Chemically, it mimics the nucleoside adenosine and thus inhibits the enzyme adenosine deaminase, which interferes with the cell's ability to process DNA. It is easily destroyed by normal cells except for blood cells, with the result that it produces relatively few side effects and results in very little non-target cell loss.

Though it has been used to treat leukemic reticuloendotheliosis, other activities like B cell leukemias and lymphomas, such as mantle cell lymphoma are still to be established. Now EMD Serono has applied for this NDA with FDA. As per the claim by the company, Cladribine Tablets has the potential to be the first orally administered disease-modifying therapy available for people living with relapsing MS, as all disease-modifying therapies currently approved for the treatment of MS are parenteral therapies. Hope FDA will approve the drug and will help many patients with relapsing forms of multiple scleorosis will have a relief in the days to come..

Ref : http://www.emdserono.com/cmg.emdserono_us/en/images/Cladribine%20Tablets%20FDA%20Submission%20FINAL%20US%20FINAL_tcm115_44365.pdf

New journal devoted to gene therapy...

As for as my knowledge goes there was no exclusive journal totally devoted to gene therapy until last year. Yeah its really interesting to to see "The Gene Therapy Review" a journal totally devoted to gene therapy. In my opinion it is an important move and was the urgent need of the hour. Now the fields like antisense drugs & gene therapy will get its due importance and hope in the days to come, will bring together all those people to share and gain the knowledge..... Those interested can follow the blog also.....

URL : http://www.genetherapyreview.com/index.php

Blog : http://www.genetherapyreview.com/gene-therapy-blog.html

Antisense drug in combination with paclitaxel for prostate cancer..

I think when I was doing some reference work for my research in 1996, I read about this drug (taxol) [In 1994 the total synthesis has been achieved by Robert Holton of Florida University. He did spend 12 years to achieve the total synthesis because of the assymmtery involved in it [It was after 40 years' after the first exctract from the tree Pacific yew (Taxus brevifolia) has shown anticancer activity and the key ingrediant identified was taxiol]. A diterpenoid, with androgen (a male hormone) blockade chemotherapy has played important role in the treatment of cancer.

Prostate cancer is the second most frequently diagnosed cancer in men after skin cancer. It is estimated there will be 218,890 new cases diagnosed in the U.S. this year(2009). Around 1 in 6 men will develop prostate cancer, a third to a half of whom will recur after local treatment and risk progression to metastatic prostate cancer. Metastatic disease invariably progresses to hormone refractory or castrate resistantprostate cancer (CRPC) if given enough time.

Prostate tumours are initially androgen (male sex hormone) dependent, and can be treated with androgen ablation therapy, however once the disease progresses to its most dangerous and aggressive form, CRPC, treatment options are limited and prognosis is poor. Treatment options depend on disease severity and include radiation and chemotherapy, which are designed to induce programmed cell death (apoptosis) of tumour cells. There is a pressing need for the development of new treatment options.

More interesting and significant results have been achieved by an Australian company (Antisense Therapeutics). i.e., in combination with taxol, antisense drug ATL1101 has yielded good results. ATL1101 is a second generation antisense inhibitor of the insulin-like growth factor-I receptor (IGF-IR) which as reported previously suppressed the growth of human prostate tumors in an animal model of prostate cancer, and slowed down transition to CRPC when used as a single agent.

The research is of great importance because of the fact that in cell culture experiments, the amount of Paclitaxel required to induce tumor cell apoptosis (cell death) was significantly reduced when used in combination with ATL1101. This ability to 'sensitize' tumor cells to the cytotoxic effects of Paclitaxel affirms ATL1101's potential as a chemo-sensitizing agent to be used in combination with existing prostate treatments to improve the outcomes for patients.

I did work for some of the intermediates (ologonucleotides) for ISIS (contract research) and am excited to see that this company has tie up with ISIS. In my opinion as ISIS , is an established company in this field of research, hope soon there will be relief for those patients for whom CRPC, treatment options are limited and prognosis is poor....

Ref: http://www.antisense.com.au/!upload_files%5Cattachment%5Casx%2009%2018%20June%202009_ATL1101.pdf

RNA interference approach for prevention and treatment of STDs ?

In my earlier blog “Diverse use of Nucleic acids”, did mention that there is much interest in the medical uses of nucleic acids. For example, antisense, ribozymes, aptamer and RNA interference (RNAi) technologies are all being developed for potential therapeutic applications. Lots of research is being done in each specified fields and in fact there are already few drugs in “antisense category” and this time something really interesting has been reported by a Post Doc., Dr. Kim Woodrow in the field of RNA interference category. The following lines briefly summerise, what actually RNAis..

RNA interference (RNAi) is a system within living cells that helps to control which genes are active and how active they are. Two types of small RNA molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to specific other RNAs and either increase or decrease their activity, for example by preventing a messenger RNA from producing a protein. RNA interference has an important role in defending cells against parasitic genes, viruses and transposons – but also in directing development as well as gene expression in general

The RNAi pathway is found in many eukaryotes including animals and is initiated by the enzyme Dicer, which cleaves long double-stranded RNA (dsRNA) molecules into short fragments of ~20 nucleotides. One of the two strands of each fragment, known as the guide strand, is then incorporated into the RNA-induced silencing complex (RISC). The most well-studied outcome is post-transcriptional gene silencing, which occurs when the guide strand base pairs with a complementary sequence of a messenger RNA molecule and induces cleavage by Argonaute, the catalytic component of the RISC complex. This process is known to spread systemically throughout the organism despite initially limited molar concentrations of siRNA. The importance of the siRNA lies in the fact that “RNAi is selective on gene expression” and hence can be used in the similar fashion like the antisense drugs (already a few drugs by ISIS, Serono and others). I did work on a few oligonucleotides (phosparothiamidates), while working in Innovasynth Technologies Limited Khopoli and know how difficult is to get the precursors of the antisense drugs. In 2006, Andrew Fire and Craig C. Mello shared the Nobel Prize in Physiology or Medicine for their work on RNA interference in the nematode worm C. elegans.

Gene interference therapy is moving rapidly from basic research to application. The PLGA packaging these researchers chose is already approved as safe and non-toxic by the FDA, speeding the path to clinical trials for infectious agents such as HPV and HIV.

Congrats Dr.Kim and co workers for this achievement. The significance of this research is the fact that “a safe and effective administration of potential antiviral drugs - small interfering RNA (siRNA) molecules using densely-loaded nanoparticles made of a biodegradable polymer known as PLGA. The researchers created a stable "time release" vehicle for delivery of siRNAs to sensitive mucosal tissue like that of the female reproductive system.

Ref : http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat2444.html

Diverse use of Nucleic acids.....

There is much interest in the medical uses of nucleic acids. For example, antisense, ribozymes, aptamer and RNA interference (RNAi) technologies are all being developed for potential therapeutic applications. The design of nucleic acids, particularly oligonucleotides, for in vivo delivery requires consideration of various factors including binding strength, target specificity, serum stability, resistance to nucleases and cellular uptake. A number of approaches have been proposed in order to produce oligonucleotides that have characteristics suitable for in vivo use, such as modified backbone chemistry, formulation in delivery vehicles and conjugation to various other moieties. Therapeutic oligonucleotides with characteristics suitable for systemic delivery would be particularly beneficial.

There are many oligonucleotides with modified chemical backbones, like peptide nucleic acids (PNAs), locked nucleic acids (LNAs), methylphosphonates, phosphoramidates and thiophosphoramidates. Each of these types of oligonucleotides has reported advantages and disadvantages. For example, peptide nucleic acids (PNAs) display good nuclease resistance and binding strength, but have reduced cellular uptake in test cultures; phosphorothioates display good nuclease resistance and solubility, but are typically synthesized as P-chiral mixtures and display several sequence- non-specific biological effects; methylphosphonates display good nuclease resistance and cellular uptake, but are also typically synthesized as P-chiral mixtures and have reduced duplex stability.

The N3'-P5'phosphoramidate internucleoside linkages are reported to display favorable binding properties, nuclease resistance, and solubility (I did work for quite some time in this field and I had opportunity to interact with Dr. Sergei Gryaznov and group). Though this field is getting wider and wider with many companies trying with some innovative ideas, the real concern in this field is that the polyanionic nature of oligonucleotides reduces the ability of the compound to cross lipid membranes, limiting the efficiency of cellular uptake.But thanks to many other groups they are trying to concentrating on this issue and hope there will be may drugs in the days to come. There are many drugs already in the market by ISIS and Geron corporation has many patents to its credit in the many patents for its novel work (Dr.Sergei, Dr.Cristzina Pongracz and many others have lot of work in this field) N3'-P5'phosphoramidate internucleoside linkages. Though there were a few players in this field of nucleic acids(5-6 years' back), now a days when ever I read any medicinal chemistry news, I do find lot many companies contributing to this field of nucleic acids. Hope there will be many drugs from this field with reduced side effects....

A new experimental drug "antagomir" (antisense oligonucleotide) as an anti- miR-21 agent..

MicroRNAs are small scraps of RNA comprising around 20 nucleotides and it is only recently that scientists have discovered their power which is they can regulate the expression (switching on and off) of a large number of human genes (they are like "master controllers"). And also these are the culprits (when microRNAs don't appear in the right place at the right time within cells) for diseases such as cancer, viral infections, inflammatory diseases and metabolic disorders. The potential to use them as targets for drugs is obvious and possibly explains why this is one of the fastest growing areas of development for new drugs and treatments.

Scientists already knew that microRNA was involved in switching genes on and off in the heart, but the underlying mechanisms and how they relate to the development of particular types of heart disease and their potential as drug targets were still relatively unknown.

Thum and colleagues discovered that miR-21 was expressed in the heart's fibroblast cells (cells that make the scaffolding of collagen or connective tissue that hold the shape of the organ) and were in greater numbers in lab mice bred to have heart failure and also in human tissue from patients who had heart failure.

In this study they showed that increasing expression of miR-21 changed the way that signals behaved in a previously unknown stress response pathway that involved the gene sprouty-1 and the MAP-kinase signaling pathway. In turn, increasing the activity of the MAP-kinase pathway led to a number of signs of heart failure, such as enhanced fibroblast survival, increased secretion of factors like fibroblast growth factor, tissue scarring (fibrosis), and cardiac dysfunction including cellular hypertrophy.

The researchers proved they could administer anti-miR-21 effectively to the heart by monitoring it with fluorescence staining. Then, in a mouse transaortic constriction model of human heart failure, they showed that anti-miR-21 silenced increased expression of miR-21 and corrected downstream changes in sprouty-1 and MAP-kinase signaling.

The interesting thing is their conclusion : Anti-miR-21, showed the most statistically significant improvement in the heart failure mouse model when given before induction of heart failure and for as long as three weeks afterward and it might be possible to target entire disease pathways with one drug. Contrats Dr. Thomas Thum.

A Deep Insight into the World Gene Therapy Market

A new market research report related to the Biotechnologies and Genetics industry about the trends in "antisense drugs".....

Can Antisense drugs revolutionize the drug discovery ?

Antisense therapy, is an important technology for drug discovery and development. It is broadly used by the pharmaceutical industry as a tool for functional genomics and as highly specific drugs for a wide range of diseases (Anticancer, anti-inflammatory, cardiovascular and neurodegenerative diseases) The most interesting factor of antisense drugs is “specificity” in contrast to the traditional drugs (which binds to the proteins and charge interactions so often ending with undesirable side effects). With the combined efforts of human genome programme and bioinformatics, we may soon have a lesser number of targets, I think this interesting field may revolutionize the drug discovery. But the real concern is, there are a few players as of now. In my opinion, something like High Throughput Screening (HTS), with co-ordination of educational and private institutes may help to have more drug contenders (as for as my knowledge goes, Southern Research Institute, Birmingham did try for antitubercular drugs, for the drug resistant strain). Let us hope, something happen in the near future…..