WOW Gene therapy with reovitus reported to selectively kill breast cancer stem cells

[Lani]

Targeting stem cells
[Dalhousie University]
Dalhousie Medical School cancer researcher Dr. Patrick Lee has proven that a common virus can infect and kill breast cancer stem cells. This breakthrough finding is published in the current issue of Molecular Therapy, the prestigious journal of the American Society of Gene Therapy.
It is only within the past few years that the scientific community has understood the full significance of cancer stem cells and the urgent need to find a means of eliminating them.
"Cancer stem cells are essentially mother cells," explains Dr. Lee, Cameron Chair in Basic Cancer Research at Dalhousie Medical School. "They continuously produce new cancer cells, aggressively forming tumours even when there are only a few of them."
Cancer stem cells are difficult to kill as they respond poorly to chemotherapy and radiation. As Dr. Lee notes, "You can kill all the regular cancer cells in a tumour, but as long as there are cancer stem cells present, disease will recur."
Dr. Lee is optimistic that his team has found the key to destroying cancer stem cells. The researchers have recently shown that human reovirus, a common virus that does not cause disease, effectively targets and kills cancer stem cells in breast cancer tissue.
"We suspected that reovirus might be effective against cancer stem cells, because we have shown time and again how well it destroys regular cancer cells," remarks Dr. Lee, who was the first in the world to discover that a benign and naturally occurring virus could selectively infect and kill cancer cells without harming healthy cells. A Calgary-based company, Oncolytics Biotech Inc., is testing reovirus in clinical trials to prove the treatments are safe and effective.
Unlike most cancer studies, which use cancer cell lines developed for laboratory use, this study used fresh breast cancer tissue. This cancer tissue was removed from a patient of Dr. Carman Giacomantonio, a Capital Health surgical oncologist who is working with Dr. Lee on the reovirus research, along with post-doctoral fellow Dr. Paola Marcato and research assistant Cheryl Dean.
In addition to its ability to kill cancer cells and cancer stem cells, reovirus stimulates the anti-cancer immune system. Since virus therapy also invokes an anti-virus response, Dr. Lee and post-doctoral fellow Dr. Shashi Gujar are working on a way to harness the immune system so it attacks cancer cells while allowing the virus to freely infect and destroy cancerous cells. "Refining this two-pronged approach to killing cancer is our next step," says Dr. Lee. "We are taking advantage of the natural characteristics of reovirus and the immune system itself to create a powerful virus-based anti-cancer therapy."
Dr. Lee's discovery that reovirus effectively targets breast cancer stem cells has captured the attention of LeadDiscovery, a UK-based organization dedicated to promoting drug discovery and development. LeadDiscovery has identified the finding to be of particular interest to the drug development sector and will feature it in its next update to the global scientific community and pharmaceutical industry.
EARLY VIEW: ABSTRACT: Oncolytic Reovirus Effectively Targets Breast Cancer Stem Cells
[Nature: Molecular Therapy]
Recent evidence suggests that cancer stem cells (CSCs) play an important role in cancer, as these cells possess enhanced tumor-forming capabilities and are resistant to current anticancer therapies. Hence, novel cancer therapies will need to be tested for both tumor regression and CSC targeting. Herein we show that oncolytic reovirus that induces regression of human breast cancer primary tumor samples xenografted in immunocompromised mice also effectively targets and kills CSCs in these tumors. CSCs were identified based on CD24-CD44+ cell surface expression and overexpression of aldehyde dehydrogenase. Upon reovirus treatment, the CSC population was reduced at the same rate as non-CSCs within the tumor. Immunofluorescence of breast tumor tissue samples from the reovirus- and mock-treated mice confirmed that both CSCs and non-CSCs were infectible by reovirus, and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) assay showed that both populations died by apoptosis. Ras, which has been shown to mediate reovirus oncolysis, was found to be present at similar levels in all cell types, and this is consistent with their comparable sensitivity to reovirus. These experiments indicate that oncolytic reovirus has the potential to induce tumor regression in breast cancer patients. More important, the CSC population was equally reduced and was as susceptible to reovirus treatment as the non-CSC population

..sorry that is reovirus

[Mary Anne in TX]

I love good news!!!!

[Shobha]

Where can I go to get infected with this reovirus?!!!

Wow. This does seem promising - perhaps a new vaccine will be developed ...

Thanks Lani! You keep our hope alive with these posts - I really look forward to them every day.

[Ellie F]

I'll second that Shobna! Lani don't know how you do it but your posts make me believe that we will beat this thing. This Easter I am praying ++ that God helps us find the cure real soon. Ellie

[chrisy]

Lani, that is exciting - the stem cell issue may be the key.

As for being infected, I'll gladly trade that virus for the cold I have right now

[hutchibk]

"A Calgary-based company, Oncolytics Biotech Inc., is testing reovirus in clinical trials to prove the treatments are safe and effective. Unlike most cancer studies, which use cancer cell lines developed for laboratory use, this study used fresh breast cancer tissue. This cancer tissue was removed from a patient of Dr. Carman Giacomantonio, a Capital Health surgical oncologist who is working with Dr. Lee on the reovirus research, along with post-doctoral fellow Dr. Paola Marcato and research assistant Cheryl Dean."

I wonder if those of us who have tissue samples could have ours used in this clinical trial?

[vickie h]

Lani, Thanks again for your posts...they do keep hope alive and remind us how fast things are moving along these days ( compared to 5 years ago). I look forward to reading your new-found info and trials everyday.
Thank You and Love,
Vickie

[PinkGirl]

http://www.oncolyticsbiotech.com/tech.html

[Rich66]

"Unlike most cancer studies, which use cancer cell lines developed for laboratory use, this study used fresh breast cancer tissue. This cancer tissue was removed from a patient of Dr. Carman Giacomantonio"

I wonder if this could accelerate the acceptability of the research since there isn't the whole "we aint mice" caveat.