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/

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: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

On-chip spin-Hall nanograting for simultaneously detecting phase and polarization singularities

08.07.2020 | Physics and Astronomy

Engineers use electricity to clean up toxic water

08.07.2020 | Agricultural and Forestry Science

Atomic 'Swiss army knife' precisely measures materials for quantum computers

08.07.2020 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>