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 Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>