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 Hot cars can hit deadly temperatures in as little as one hour
24.05.2018 | Arizona State University

nachricht 3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg

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: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>