Credit: Lance Liotta
New research has revealed a mechanism of drug resistance in acute myeloid leukemia (AML) that may also occur in other cancers.
Investigators found evidence suggesting that glioma-associated protein 1 (GLI1) and the UDP glucuronosyltransferase (UGT1A) family of enzymes drive resistance to 2 drugs—ribavirin and cytarabine—in AML.
But the researchers were able to overcome this resistance by genetic or pharmacologic inhibition of GLI1.
They described this research in a letter to Nature.
“By studying drug-resistant cancer cells from AML patients and head and neck tumors, we found that a gene called GLI1 is dramatically overactive in these cells,” said study author Hiba Zahreddine, a doctoral student at the University of Montreal in Canada.
“[W[e were then able to show that this results in a specific chemical change to the drugs that prevents their toxicity toward the cancer cells,” said author Kathy Borden, PhD, of the University of Montreal’s Institute for Research in Immunology and Cancer.
Specifically, the investigators found that UGT1A enzymes add glucuronic acid to the drugs, thereby modifying their activity. And GLI1 alone is sufficient to drive UGT1A-dependent glucuronidation of ribavirin and cytarabine, which fuels drug resistance.
Fortunately, the researchers found that inhibiting GLI1, either genetically or with pharmacologic inhibitors, could force cancer cells to revert to a treatment-sensitive state.
The team therefore hopes that using GLI1 inhibitors in combination with ribavirin, cytarabine, or other therapies can overcome treatment resistance in patients with AML. The investigators have received approval from Health Canada to conduct a new clinical trial to test this theory.
“If this new approach is successful, it could have very broad applications, since the mode of action of ribavirin suggests that it could be effective against up to 30% of all cancers, including some types of breast, prostate, colon, stomach, and head and neck cancers, in addition to AML,” said Morris Goodman, co-founder and Chairman of the Board of Pharmascience Inc., the company that manufactured the ribavirin for this research.
