Cancerous Tumors Resist Treatment Via Vessel Co-Option

For the first time, a new study was able to demonstrate how cancerous tumors can become drug resistant over time through vessel co-option.

Researchers describe the process of vessel co-option as tumors learning to steal normal blood vessels from the surrounding tissue.

Angiogenesis is an important factor for cancer growth and many anti-angiogenic drugs have been developed to combat this. Newly designed therapies that block angiogenesis and vessel co-option could be more effective in the treatment of cancer.

A study published in the Journal of the National Cancer Institute used mice to determine how hepatocellular carcinoma could become resistant to sorafenib, an anti-angiogenic drug.

The results of the study showed the tumors that initially responded to treatment were reliant on the growth of their own blood vessels. However, a resistance was developed instead by actively stealing the normal pre-existing blood vessels of the liver.

“Our study is the first to show that cancers can adapt to treatment by actively co-opting blood vessels from nearby tissues as a mechanism of drug resistance,” said study co-leader Andrew Reynolds.

Additionally, researchers found that switching to vessel co-option was reversible. Once treatment was stopped, the tumors went back to using angiogenesis, suggesting that patients can respond to the same anti-angiogenic drug again after stopping treatment.

These findings led researchers to believe the treatment could be used for metastatic breast cancer and metastatic bowel cancer as well, and scientists from The Institute of Cancer Research have begun investigating this notion.

Since there are currently no drugs that target vessel co-option, researchers explored exactly how the process works. They found that when cancer cells co-opt vessels, it increases their mobility, suggesting that targeting cancer cell movement could be used to block vessel co-option.

“Although the current study was focused on liver cancer in mice, we are also currently investigating whether our results are relevant for patients affected by breast and bowel cancer,” Reynolds said. “Our research also emphasizes the importance of further studies to better understand the process of vessel co-option, which seems to play an important role in tumor growth but has been relatively under-studied.”

Researchers hope their research can be applied to help develop future treatments in cancer patients.

“This new insight into how cancers could be commandeering nearby blood vessels to resist treatments may be significant for a number of disease areas,” said researcher Katie Goates, senior research communications officer at Breast Cancer Now. “We hope that this knowledge can now be harnessed and applied to help slow the spread of breast cancer. Ultimately, if we can stop breast cancers spreading in the first place — where they become incurable – we’ll finally be able to stop women losing their lives to this dreadful disease.”