The common asthma drug montelukast may boost the effectiveness of cancer immunotherapies, new research suggests.
Montelukast, sold under the brand name Singulair by Organon and available in generic versions, blocks a key molecule called CysLTR1 that plays a role in asthma. The molecule is also used by tumors to suppress the body's immune defenses, researchers found in lab experiments.
By blocking CysLTR1 and restoring those immune defenses, montelukast improves the effectiveness of cancer immunotherapy drugs, according to a report of the study published in Nature Cancer.
In test tube experiments with human cancer cells and in mice with various types of cancer, researchers found tumors “turn on” CysLTR1 to increase production of so-called polymorphonuclear myeloid-derived suppressor cells, which resemble immune cells called neutrophils but which actually suppress tumor-fighting immune defenses.
“When we turned off this switch, either genetically or with (montelukast), we not only slowed tumor growth, but also helped the immune system recover its ability to fight the cancer,” study leader Dr. Bin Zhang of Northwestern University Feinberg School of Medicine in Chicago said in a statement.
Because montelukast and other drugs that block CysLTR1 are already FDA-approved, patient trials could start soon, the researchers said.
“We may be able to quickly and safely test it in cancer patients to improve immunotherapy. Especially in aggressive cancers, like triple-negative breast cancer, where new options are urgently needed,” Zhang said.
“The next steps are to confirm this mechanism in patients, identify who will benefit most, optimize how we use these drugs especially in combination with immunotherapy, and begin carefully designed clinical trials.”
