P52 gene, arrows show locations of common mutations 

(Image courtesy www.bioinf.org)

Following on from my last article on using gene therapy for increasing survival in head and neck cancer, Professor Jack Roth, M.D., professor in M. D. Anderson’s Department of Thoracic & Cardiovascular Surgery and colleagues are now focusing on ways to deliver p53 and other tumor-suppressing genes systemically - through intravenous delivery.

The p53 gene is inactivated in many types of cancer. Its normal role is to halt the division of a defective cell and then force the cell to kill itself.

Advexin has to be injected straight into the tumor, but that’s not workable for many cancers. Head and neck cancer kills patients by recurring, not spreading to other organs, but most cancer deaths involve metastasis.

By wrapping tumor-suppressing genes in tiny balls of fat, Roth and colleagues hope to be able to treat more invasive cancers. While p53 nanoparticles are still in preclinical development, those that deliver another tumor-suppressor called FUS1 are in a phase I clinical trial for non-small cell lung cancer. Through 19 patients, the dose escalation study has yet to encounter significant side effects.

Injected nanoparticles gather mainly in tumors, where they are taken up and dissolved, leaving the tumor-suppressor gene at work in the cell. A version that combines FUS1 and p53 is under development.

Elaine Warburton  www.geneticsandhealth.com

Thank you to Jennifer Texada at MD Anderson for bringing this great cancer treatment discovery to my attention….

(Image courtesy Introgen Therapeutics)

A gene therapy invented at The University of Texas M. D. Anderson Cancer Center is the first to succeed in a U.S. phase III clinical trial for cancer.  Introgen Therapeutics, Inc a spin out from MD Anderson, reported results of its phase III trial of Advexin, a modified adenovirus that expresses the tumor-suppressing gene p53, for end-stage head and neck cancer.

The p53 gene is inactivated in many types of cancer. Its normal role is to halt the division of a defective cell and then force the cell to kill itself.

“Cells become cancerous because p53 no longer functions. Restoring p53 works unlike any current cancer treatment because it treats the cancer genome,”said Jack Roth, M.D., professor in M. D. Anderson’s Department of Thoracic & Cardiovascular Surgery, who invented the drug and co-founded Introgen.

The trial showed that p53 expression in the patient’s tumor before treatment is a reliable biomarker for how to treat head and neck cancer. Patients with a favorable p53 profile who received Advexin had an average survival of just over 7 months, compared with just under 3 months for those whose tumor expressed high levels of mutant p53 before treatment. Patients with this unfavorable profile were better off taking the chemotherapy drug methotrexate, resulting in n average survival of just under 6 months.

“The important finding is that patients who benefit from treatment can be identified with the p53 biomarker. The biomarker will enable physicians to personalize treatment,” said Roth.

Better Quality of Life

Patients treated with Advexin experienced far fewer harmful side effects such as pneumonia than those who received methotrexate. The incidence of inflammation of the mouth lining and a decrease in white blood cells, for example, both dropped to zero for those receiving Advexin.

“That certainly results in a better quality of life,” Roth noted, which makes sense because p53 does not cause problems in normal cells.

Roth’s lab has been developing gene therapy for cancer since 1990. “We wanted to go beyond conventional treatment, because most of those treatments were not very effective,” Roth said. “Surgery and radiation are limited to the local tumor and once given, it’s very hard to repeat those therapies.  Chemotherapy inhibits DNA replication, but it also interferes with normal cells.”

Elaine Warburton  www.geneticsandhealth.com