CHAMPAIGN, Ill. -- A new approach to treating breast cancer kills 95-100% of cancer cells in mouse models of human estrogen-receptor-positive breast cancers and their metastases in bone, brain, liver and lungs. The newly developed drug, called ErSO, quickly shrinks even large tumors to undetectable levels.
[...] "Even when a few breast cancer cells do survive, enabling tumors to regrow over several months, the tumors that regrow remain completely sensitive to retreatment with ErSO," said U. of I. biochemistry professor David Shapiro, who led the research with Illinois chemistry professor Paul Hergenrother. "It is striking that ErSO caused the rapid destruction of most lung, bone and liver metastases and dramatic shrinkage of brain metastases, since tumors that have spread to other sites in the body are responsible for most breast cancer deaths," Shapiro said.
[...] ErSO is nothing like the drugs that are commonly used to treat estrogen-receptor-positive cancers, Shapiro said.
"This is not another version of tamoxifen or fulvestrant, which are therapeutically used to block estrogen signaling in breast cancer," he said. Even though it binds to the same receptor that estrogen binds, it targets a different site on the estrogen receptor and attacks a protective cellular pathway that is already turned on in cancer cells, he said.
[...] "Many of these breast cancers shrink by more than 99% in just three days," Shapiro said. "ErSO is fast-acting and its effects on breast cancers in mice are large and dramatic."
The pharmaceutical company Bayer AG has licensed the new drug and will explore its potential for further study in human clinical trials targeting estrogen-receptor-positive breast cancers, the researchers said. The researchers will next explore whether ErSO is effective against other types of cancers that contain estrogen receptor.
Matthew W. Boudreau, Darjan Duraki, Lawrence Wang, et al. A small-molecule activator of the unfolded protein response eradicates human breast tumors in mice [$], Science Translational Medicine (DOI: 10.1126/scitranslmed.abf1383)