Tiny oxygen generators boost effectiveness of anticancer treatment

ScienceDaily (Aug. 31, 2011) — Researchers have created and tested miniature devices that are implanted in tumors to generate oxygen, boosting the killing power of radiation and chemotherapy.

The technology is designed to treat solid tumors that are hypoxic at the center, meaning the core contains low oxygen levels.

"This is not good because radiation therapy needs oxygen to be effective," said Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering. "So the hypoxic areas are hard to kill. Pancreatic and cervical cancers are notoriously hypoxic. If you generate oxygen you can increase the effectiveness of radiation therapy and also chemotherapy."

The new "implantable micro oxygen generator" is an electronic device that receives ultrasound signals and uses the energy to generate a small voltage to separate oxygen and hydrogen from water - a chemical operation called water electrolysis.

"We are putting these devices inside tumors and then exposing the tumors to ultrasound," Ziaie said. "The ultrasound energy powers the device, generating oxygen.

The devices were created at the Birck Nanotechnology Center in the university's Discovery Park. Purdue researchers are working with Song-Chu (Arthur) Ko, an assistant professor of clinical radiation oncology at the Indiana University School of Medicine.

Researchers have tested the devices in pancreatic tumors implanted in mice, showing they generated oxygen and shrunk tumors faster than tumors without the devices. The devices are slightly less than one centimeter long and are inserted into tumors with a hypodermic biopsy needle.

"Most of us have been touched by cancer in one way or another," Ziaie said. "My father is a cancer survivor, and he went through many rounds of very painful chemotherapy. This is a new technology that has the potential to improve the effectiveness of such therapy."

Findings are detailed in a research paper appearing online this month in Transactions on Biomedical Engineering. The paper was written by research assistant professor Teimour Maleki, doctoral students Ning Cao and Seung Hyun Song, Ko and Ziaie.

"The implantable mini oxygen generator project is one of 11 projects the Alfred Mann Institute for Biomedical Development at Purdue University (AMIPurdue) has sponsored," Ziaie said. "AMIPurdue has been instrumental in providing the development funding of roughly $500,000 on this project. And beyond funding, the AMIPurdue team has also helped us with market research, physician feedback, industry input, as well as intellectual property and regulatory strategy. We have been able to accomplish a great deal in a short time due to the collaborative effort with AMIPurdue."

A patent application has been filed for the design.

Future work may focus on redesigning the device to make it more practical for manufacturing and clinical trials.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Purdue University.

Journal Reference:

T. Maleki, N. Cao, S. Song, C. Kao, S.-C. Ko, B. Ziaie. An Ultrasonically-Powered Implantable Micro Oxygen Generator (IMOG). IEEE Transactions on Biomedical Engineering, 2011; DOI: 10.1109/TBME.2011.2163634

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

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Intravenous virus eyed as possible cancer treatment

Scientists from the Ottawa Hospital Research Institute have succeeded in delivering a virus intravenously that only attacks cancer tumours and doesn't harm healthy tissues, according to a new study in the scientific journal Nature.

Dr. John Bell, a senior scientist at OHRI and senior co-author of the study, said the investigators were trying to demonstrate that it is possible to deliver such a virus intravenously in people. Previously, it had only been done in animals.

Ultimately, the goal is to use viruses as a cancer treatment, likely in combination with chemotherapy.

"In this study, the way we designed the virus is that it can only grow in cancers and cannot grow in any normal tissues," Bell said. "We think that with this selective approach we may be able to treat cancer continuously with the virus and hopefully effect a complete remission of the disease."

The study involved 23 patients (seven from Ottawa Hospital) who had advanced cancers that had spread to multiple organs. The objective was to prove that viruses could be delivered to tumours through the bloodstream, not to actually treat the patients involved.

"Intravenous delivery is crucial for cancer treatment because it allows us to target tumours throughout the body as opposed to just those that we can directly inject," Bell said, "The study is also important because it shows that we can use this approach to selectively express foreign genes in tumours, opening the door to a whole new suite of targeted cancer therapies."

Bell said those kinds of therapies are desirable because of the restrictions of current forms of treatment.

"The limitations of [chemotherapy and radiation therapy] are that they not only attack the cancer but unfortunately they also attack normal tissues," Bell said.

Bell added that the virus is particularly effective on solid tumors such as in the skin, breast, prostate or pancreas but less effective in leukemia and lymphoma.

Dr. Michael Baker, cancer researcher and professor of medicine at the University of Toronto, said the study is extremely promising but there is a way to go before it translates into a way of treating cancer.

"My educated guess would be we're talking two to four years before this is proven to be safe enough to carry actual therapeutic drugs and other destructive items right to the cancer cell, that's still a work in progress," Baker said.

The study called for patients to receive a single intravenous infusion of the virus (JX-594) at one of five dosage levels. Biopsies of their tumours were obtained 10 days later. In the two highest dosage groups, there was evidence in seven out of eight patients of viral replication in their tumours but not in healthy normal tissue.

Patients reported some side effects consisting of flu-like symptoms for less than 24 hours.

The virus used, a distant relative of smallpox that has been used as a vaccine against smallpox, seemed to be particularly effective at searching for cancerous tumours, according to the study.

Although other viruses have been studied, Baker said this particular virus has a "peculiar capacity."

"It's actually big enough to put things into it. And this experiment showed that those viruses are capable of carrying sizable other molecules to where they are supposed to go and then they multiply — many viruses are just passive carriers that get into the cell — [whereas] these viruses are alive and multiply and spread to other parts of the body where there are other cancers that have been spread."

Bell said the next step is to have trials consisting of a multi-dose regime and open trials around the world to test the virus more thoroughly.

"We'll hope to see we can improve outcomes of patient survival in these larger trials."

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