Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Light-activated therapy and radiation combined effectively for treating tumors

03.03.2003


Dartmouth researchers report in the March 1 issue of Cancer Research they have discovered an effective combination therapy to treat tumors. In the journal, which is a publication of the American Association for Cancer Research, the researchers report that administering light-activated, or photodynamic, therapy (PDT) immediately before radiation therapy appears to kill tumors more effectively than just the sum of the two treatments.



"Our study shows that the close combination of the two treatments complement each other, allowing more effective therapy for the same delivered dose," says Brian Pogue, the lead author, an Associate Professor at Dartmouth’s Thayer School of Engineering and a Research Scientist at Harvard Medical School.

PDT is used to treat a variety of illnesses, from lung cancer to age-related blindness. The treatment uses a light-activated drug to kill tumor tissue. The drug, verteporfin in this study, is designed to accumulate within tissues with tumor-like characteristics, such as leaky vasculature and rapidly growing cells.


Pogue and his colleagues studied the effectiveness of a combined approach for administering the photodynamic therapy and subsequent radiation for treating a mouse tumor. The multidisciplinary research team is composed of faculty from Dartmouth’s Thayer School of Engineering, Dartmouth Medical School, the Norris Cotton Cancer Center at Dartmouth-Hitchcock Medical Center, and Massachusetts General Hospital.

"This finding could spark a new direction and new applications for PDT," says Pogue. "The key feature of this treatment is that the mechanism of cellular damage appears to be significantly targeted towards the cellular mitochondria, unlike radiation treatment that inflicts DNA damage."

Verteporfin is a specially designed porphyrin molecule. Porphyrins occur widely in nature, are light sensitive and play an important role in various biological processes. Heme is one notable porphyrin found in hemoglobin, and it is responsible for oxygen transport and storage in tissues. Chlorophyll is another type of porphyrin. When activated by a beam of light, porphyrins interact with oxygen in the tissues, producing a kind of oxygen, called singlet state oxygen, which is toxic to cells. This photochemical process is an efficient way to kill tissues by producing massive doses of singlet state oxygen.

Oxygen in tumors is a key component in both radiation therapy and PDT. The presence of oxygen significantly increases the ability of the therapy to induce singlet oxygen, which in turn more effectively kills the tumor tissue. "In this study, we found that verteporfin appears to increase oxygen within the tumor," says Pogue, "and this makes the subsequent radiation more effective."

Previous studies by Pogue and colleagues have shown that PDT with verteporfin targets the mitochondria (responsible for cellular respiration), but only if the verteporfin is delivered in a manner that allows distribution throughout the tumor with partial clearance from the blood vessels. This means that the drug is cleared rapidly from the blood stream by the kidneys and the liver, which is a key feature in being compatible with outpatient medical treatment. This approach of targeting the tumor tissue rather than the blood vessels was further developed in the study.

The researchers discovered that applying PDT to kill the mitochondria of the tumor cells caused a decrease in oxygen consumption, yet oxygen was still being delivered to the tumor tissue. This phenomenon resulted in an increase in available oxygen within the tumor, which improves PDT’s ability to induce singlet-state oxygen and also allows the immediately-following second therapy of radiation to be more effective. Increased oxygenation of tumors is well-known to significantly increase the radiation sensitivity of the tissue, according to Pogue.

The study was carried out in subcutaneous radiation-induced fibrosarcoma (RIF-1) tumors in mice. The tumor-killing effects were quantified by following the shrinkage of tumor volume over time after the treatments. The most effective therapy was determined by measuring the delay in the regrowth rate of the tumor, which is a standard method in cancer therapy research.

Pogue’s co-authors on this study were: Julia O’Hara, Research Associate Professor of Radiology at Dartmouth Medical School; Eugene Demidenko, Research Associate Professor at the Norris Cotton Cancer Center at Dartmouth-Hitchcock Medical Center and Adjunct Associate Professor of Mathematics at Dartmouth College; Carmen Wilmot, Radiology Laboratory Technician at Dartmouth Medical School; Isak Goodwin, a Dartmouth alum from the class of ’01 who will attend Drexel University Medical School this fall; Bin Chen; Research Associate at Dartmouth’s Thayer School of Engineering, Harold Swartz, Professor of Radiology at Dartmouth Medical School, and Tayyaba Hasan, Professor at Wellman Laboratories of Photomedicine at the Massachusetts General Hospital and Harvard Medical School.


###
This study was funded by: the National Cancer Institute through grants RO1 CA78734, PO1 CA84203 and by the Electron Paramagnetic Resonance Center for the Study of Viable Systems at Dartmouth Medical School supported by the National Center for Research Resources.


Sue Knapp | EurekAlert!
Further information:
http://www.dartmouth.edu/

More articles from Health and Medicine:

nachricht Custom-tailored strategy against glioblastomas
26.09.2016 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New leukemia treatment offers hope
23.09.2016 | King Abdullah University of Science and Technology

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

How to merge two black holes in a simple way

26.09.2016 | Physics and Astronomy

Australian technology installed on world’s largest single-dish radio telescope

26.09.2016 | Physics and Astronomy

New mechanisms uncovered explaining frost tolerance in plants

26.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>