MedicineWorld.Org
Your gateway to the world of medicine
Home
News
Cancer News
About Us
Cancer
Health Professionals
Patients and public
Contact Us
Disclaimer

Medicineworld.org: Tumor Blood Flow Can Improve Chemotherapy

Back to cancer blog Blogs list Cancer blog  


Subscribe To Cancer Blog RSS Feed  RSS content feed What is RSS feed?

Tumor Blood Flow Can Improve Chemotherapy




Tumor Blood Flow Can Improve Chemotherapy
A therapy for neuroblastoma that lands a one-two punch works best when the second punch is timed to take maximum advantage of the first one, as per results of studies at St. Jude Childrens Research Hospital. Neuroblastoma is a pediatric solid tumor that arises from cells in the peripheral nervous system.

The finding holds promise for improving neuroblastoma therapy by using the drug bevacizumab to block VEGF, a protein that stimulates blood vessel growth in tumors and then following with the chemotherapy drug topotecan, which depends on blood vessels to penetrate the tumor and kill the cancer cells. A report on this work appears in the current issue of Clinical Cancer Research.

Results of the current study are particularly important because drugs such as bevacizumab are being reviewed in clinical trials for children with neuroblastoma. However, there are no standard guidelines for how much of the drug to give or when to give it. Such guidelines would be particularly helpful for developing combination treatment with both bevacizumab and chemotherapy drugs, not only for neuroblastoma, but also for other tumors.

The results of our study are a significant step toward establishing such guidelines, said Andrew Davidoff, M.D., director of surgical research at St. Jude, and the reports senior author.

The St. Jude team based their strategy on prior findings that suggested blocking VEGF at first improves the tumors vasculature, or blood vessel system, by eliminating weak and faulty vessels, while temporarily sparing healthy, normal blood vessels. The researchers reasoned that if they treated tumors with bevacizumab first, the temporarily improved tumor circulation would more efficiently deliver topotecanbut only if they timed this one-two punch correctly.

A growing tumor releases VEGF to stimulate growth of the blood vessels that support its own growth, Davidoff said. But much of this new vasculature is poorly constructed and leaks fluid into the spaces around the malignant cells, increasing the pressure inside the tumor. This increased pressure outside the vasculature acts like a wall to prevent cancer drugs from passing through the blood vessels.

Bevacizumab eliminates the shoddy vasculature, temporarily sparing the more sturdily built vessels, which do not leak fluid, but deliver the drug throughout the tumor, Davidoff said.

Davidoffs team first treated mouse models that carried transplanted human neuroblastomas with a single dose of bevacizumab. They studied the changes in the tumor vasculature at different times after therapy with a single dose of bevacizumab; finally, they studied how well topotecan penetrated the tumor and inhibited its growth when given at different intervals after bevacizumab.

The scientists showed that bevacizumab reduced the density of the tumors vasculature to less than 30 percent of that in untreated tumors within seven days, accompanied by a significant decrease in pressure in the tumor caused by fluid passing through from the blood vessels. The remaining, normalized vasculature perfused the tumor more thoroughly than before therapy with bevacizumab; and the amount of topotecan it carried throughout the tumor was about 80 percent more when given one to three days after bevacizumab in comparison to when both drugs were given either at the same time or seven days apart.

When the scientists administered topotecan to the tumor-bearing mice three days after bevacizumab, the size of the tumors was only 36 percent of the size of untreated tumors, in comparison to 88 percent when mice were treated with bevacizumab alone; 54 percent when treated with topotecan alone; and 44 percent when tumor-bearing mice were treated with both drugs at the same time.

We observed in the mouse model of neuroblastoma that the maximum amount of topotecan reached the tumor and had maximum tumor-reducing effect if we waited three days after administering bevacizumab, Davidoff said. This suggested that combination therapy of children with neuroblastoma should take into account that there is a window of opportunity for improving topotecan delivery after therapy with bevacizumab. Further studies should tell us how long that window is open.


Posted by: Janet    Source




Did you know?
A therapy for neuroblastoma that lands a one-two punch works best when the second punch is timed to take maximum advantage of the first one, as per results of studies at St. Jude Childrens Research Hospital. Neuroblastoma is a pediatric solid tumor that arises from cells in the peripheral nervous system.

Medicineworld.org: Tumor Blood Flow Can Improve Chemotherapy

Main Page| Cancer blog| Cancer blogs list| Lung cancer blog| Colon cancer blog| Prostate cancer blog| Breast cancer blog| Diabetes watch blog| Heart watch blog| Allergy blog| Bladder cancer blog| Cervical cancer blog| Colon cancer news blog| Diabetes news blog| Esophageal cancer blog| Gastric cancer blog| Health news blog| Heart news blog| Infectious disease blog| Kidney watch blog| Lung disease blog| Lung cancer news blog| Mesothelioma blog| Neurology blog| Breast cancer news blog| OBGYN blog| Ophthalmology blog| Ovarian cancer blog| Cancer news blog| Pancreas cancer blog| Pediatrics blog| Prostate cancer news blog| Psychology blog| Research blog| Rheumatology blog| Society news blog| Uterine cancer blog| Weight watch blog|

Copyright statement
The contents of this web page are protected. Legal action may follow for reproduction of materials without permission.