Yale University Scientists Synthesize Long-Sought-After Anticancer Agent

A team of Yale University scientists has synthesized for the first time a chemical compound  called “lomaiviticin aglycon, ” which led to the development of a new class of molecules that appear to target and destroy cancer stem cells.

A team of Yale University scientists has synthesized for the first time a chemical compound called “lomaiviticin aglycon,” which led to the development of a new class of molecules that appear to target and destroy cancer stem cells.

Chemists worldwide have been interested in lomaiviticin’s potential anticancer properties since its discovery in 2001. But so far, they have been unable to obtain significant quantities of the compound, which is produced by a rare marine bacterium that cannot be easily coaxed into creating the molecule. For the past decade, different groups around the world have been trying instead to synthesize the natural compound in the lab, but without success.

Dr. Seth Herzon (center), along with team members Christina Woo and Liang Lu, synthesized a naturally occurring anticancer compound that scientists worldwide have been trying to replicate in the lab for nearly a decade.

Now a team at Yale, led by chemist Dr. Seth Herzon, has managed to create lomaiviticin aglycon for the first time, opening up new avenues of exploration into novel chemotherapies that could target cancer stem cells, thought to be the precursors to tumors in a number of different cancers including ovarian, brain, lung, prostate and leukemia. Their discovery appears online today in the Journal of the American Chemical Society.

“About three quarters of anticancer agents are derived from natural products, so there’s been lots of work in this area,” Herzon said. “But this compound is structurally very different from other natural products, which made it extremely difficult to synthesize in the lab.”

In addition to lomaiviticin aglycon, Herzon’s team also created smaller, similar molecules that have proven extremely effective in killing ovarian stem cells, said Gil Mor, M.D., Ph.D., a researcher at the Yale School of Medicine who is collaborating with Herzon to test the new class of molecules’ potential as a cancer therapeutic. This family of compounds are called “kinamycins.” The reactive core of the kinamycins also plays a key role in lomaiviticin aglycon, which is even more toxic and could prove even more effective in destroying cancer cells.

The scientists are particularly excited about lomaiviticin aglycon’s potential to kill ovarian cancer stem cells because the disease is notoriously resistant to paclitaxel (Taxol) and carboplatin, two of the most commonly used ovarian cancer chemotherapy drugs. “Ovarian cancer has a high rate of recurrence, and after using chemotherapy to fight the tumor the first time, you’re left with resistant tumor cells that tend to keep coming back,” Mor explained. “If you can kill the stem cells before they have the chance to form a tumor, the patient will have a much better chance of survival — and there aren’t many potential therapies out there that target cancer stem cells right now.”

Image of one of the kinamycin compounds synthesized by Yale researchers destroying ovarian cancer cells (the spherical objects) in less than 48 hours in lab tests. (Credit: Gil Mor)

Herzon’s team, which managed to synthesize the molecule in just 11 steps starting from basic chemical building blocks, has been working on the problem since 2008 and spent more than a year on just one step of the process involving the creation of a carbon-carbon bond. It was an achievement that many researchers deemed impossible, but while others tried to work around having to create that bond by using other techniques, the team’s persistence paid off.

“A lot of blood, sweat and tears went into creating that bond,” Herzon said. “After that, the rest of the process was relatively easy.”

Next, the team will continue to analyze the compound to better understand what’s happening to the stem cells at the molecular level. The team hopes to begin testing the compounds in animals shortly.

“This is a great example of the synergy between basic chemistry and the applied sciences,” Herzon said. “Our original goal of synthesizing this natural product has led us into entirely new directions that could have broad impacts in human medicine.”

Other authors of the paper include Liang Lu, Christina M. Woo and Shivajirao L. Gholap, all of Yale University.

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Novogen’s NV-128 Targets mTOR Pathway To Block Differentiation and Induce Cell Death in Ovarian Cancer Stem Cells

“Data just presented at the Annual Meeting of the American Association for Cancer Research in Denver has demonstrated that NV-128, a Novogen, Limited (ASX: NRT NASDQ: NVGN) synthetic isoflavonoid compound, not only induces cell death in Ovarian Cancer Stem Cells (OCSCs), but also blocks their differentiation into structures which are required to support tumor growth.  In a poster presentation by Ayesha Alvero, MD, of Yale University School of Medicine, Department of Obstetrics, Gynecology and Reproductive Science, it was revealed that in addition to an inhibitory effect on OCSC growth, NV-128 displays a remarkable ability to inhibit differentiation of OCSCs into formation of new blood vessels. … ‘We have now demonstrated that by inhibiting the mTOR pathway in both the cancer stem cells and the mature cancer cells, we are able to inhibit development of structural elements necessary for tumor development as well as limit the number of cancer cells,’ Professor Mor said. ‘These results open a new avenue for the development of better treatment modalities for ovarian cancer patients.’ …”

“(Sydney Australia and New Canaan, Connecticut – 20 April, 2009) – Data just presented at the Annual Meeting of the American Association for Cancer Research in Denver has demonstrated that NV-128, a Novogen, Limited (ASX: NRT NASDQ: NVGN) synthetic isoflavonoid compound, not only induces cell death in Ovarian Cancer Stem Cells (OCSCs), but also blocks their differentiation into structures which are required to support tumor growth.

alvero

Ayesha Alvero, M.D., Associate Research Fellow, Department of Obstetrics, Gynecology and Reproductive Science, Yale University School of Medicine

In a poster presentation by Ayesha Alvero, MD, of Yale University School of Medicine, Department of Obstetrics, Gynecology and Reproductive Science, it was revealed that in addition to an inhibitory effect on OCSC growth, NV-128 displays a remarkable ability to inhibit differentiation of OCSCs into formation of new blood vessels.

The anti-proliferative effects were demonstrated to be achieved as a result of NV-128 inhibiting phosphorylation of the pro-survival mTOR pathway resulting in mitochondrial depolarisation and cell death. Time lapsed photographic morphometry revealed in graphic detail how NV-128 induces morphological changes in OCSCs after 24 hours, even when dosed as low as 1μg/ml with a progressive “clearing” of cytoplasm and condensation of nuclear material.

The effect of NV-128 on OCSC vessel formation was observed by plating OCSCs in high-density matrigel either without NV-128 (controls) or in the presence of 0.1 mg/ml NV-128 and observing for 48 hours. Whereas the control cultures showed differentiation of the stem cells into endothelial-type cells forming structurally intact blood vessels in the culture plates, cells cultured in the presence of NV-128 showed no differentiation and no structural elements were observed.

OCSCs represent a highly chemo-resistant cell population, allowing them to survive conventional chemotherapy. Thus these cells are considered to be the potential source of tumor induction and post-treatment recurrence.

The team from Yale University, headed by Professor Gil Mor, recently reported the identification and characterisation of OCSCs using the CD44 marker and demonstrated pronounced up-regulation of the mTOR survival pathway in these cells. They previously reported that NV-128 is able to specifically induce mTOR dephosphorylation resulting in inhibition of both mTORC1 and mTORC2 activity in mature ovarian cancer cells derived from established human cancers and cultured in vitro. In mice with human ovarian cancers established by grafting techniques (xenografts) NV-128 caused substantial cancer cell death, reducing tumor growth with no apparent toxic side-effects.

mor

Gil Mor, M.D., Ph.D., Associate Professor, Department of Obstetrics, Gynecology and Reproductive Science, Yale University School of Medicine

‘We have now demonstrated that by inhibiting the mTOR pathway in both the cancer stem cells and the mature cancer cells, we are able to inhibit development of structural elements necessary for tumor development as well as limit the number of cancer cells,’ Professor Mor said. ‘These results open a new avenue for the development of better treatment modalities for ovarian cancer patients.’

‘We are encouraged by these data from animal studies showing a combination of anti-cancer activities of NV-128, coupled with an apparently high safety profile,’ said Professor Alan Husband, Group Director of Research for the Novogen group. ‘This anti-angiogenic effect, coupled with the absolute effects on cell survival, demonstrate the potential for NV-128 to become a powerful new tool in prevention as well as treatment of cancer.’

Novogen has previously reported on the parallel effects of NV-128 in non-small cell lung cancer models and the Company intends to pursue this, as well as ovarian cancer, as target indications.

Novogen is currently in advanced negotiations with its majority owned subsidiary, Marshall Edwards, Inc. (MEI), to out-license NV-128 to MEI for its clinical development as a potential cancer therapeutic. To view an online abstract relating to this study, [CLICK HERE].

About NV-128

NV-128 does not rely on the traditional approach of caspase-mediated apoptosis, a death mechanism which is not effective in cancer cells that have become resistant to chemotherapy. Rather, NV-128 uncouples a signal transduction cascade which has a key role in driving protein translation and uncontrolled cancer cell proliferation. Further, NV-128 induces mitochondrial depolarisation via the novel mTOR pathway. In cancer cells, mTOR signals enhance tumor growth and may be associated with resistance to conventional therapies. Inhibition of the mTOR pathway appears to shut down many of these survival pathways, including proteins that protect the mitochondria of cancer cells. Animal studies have shown that NV-128 not only significantly retards tumor proliferation, inhibiting the progression of ovarian cancers-engrafted into mice, but produces this effect without apparent toxicity. This effect was shown to be due to caspase-independent pathways involving inhibition of the mTOR pathway. Unlike analogues of rapamycin, which target only mTORC1, NV-128’s capacity to inhibit mTOR phosphorylation enables it to inhibit both mTORC1 and mTORC2 activity. This blocks growth factor-driven activation of AKT and the potential for development of chemoresistance.

About Novogen Limited

Novogen Limited (ASX: NRT; NASDAQ: NVGN) is an Australian biotechnology company based in Sydney, Australia, that is developing a range of oncology therapeutics from its proprietary flavonoid synthetic chemistry technology platform. More information on NV-128 and on the Novogen group of companies can be found at www.novogen.com.

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Additional Information Re Novogen’s NV-128: