A medication that has been quietly lowering blood pressure for decades might also be the wingman cancer drugs never knew they needed. A new study from the Dartmouth Cancer Center (DCC) reveals that telmisartan, an FDA-approved antihypertensive, significantly boosts the cancer-killing power of olaparib, a PARP inhibitor typically reserved for tumors with specific DNA repair defects. The findings, published in The Journal for ImmunoTherapy of Cancer, suggest that the cheap, safe, and widely available drug could expand the pool of patients who benefit from this class of targeted therapies.

"This study shows that a common, safe, tolerable, convenient, and inexpensive drug may significantly improve how well an important class of cancer therapies works," said Tyler J. Curiel, MD, MPH, FACP, the study's senior and lead author, in a statement that sounds almost too good to be true.

PARP inhibitors like olaparib work by exploiting weaknesses in cancer cells' DNA repair systems, particularly those with BRCA mutations. But many cancers lack these defects, rendering the drugs useless, and even responsive tumors often develop resistance. The Dartmouth team found that telmisartan makes tumors more sensitive to PARP inhibitors regardless of their DNA repair status. In preclinical experiments, the combo increased DNA damage inside cancer cells while activating immune defenses - specifically, boosting type I interferons that help the immune system spot and attack cancer.

Telmisartan belongs to the angiotensin II receptor blocker (ARB) family, but its cancer-enhancing effects appear to be unique among its peers. It also lowered levels of PD-L1, a protein cancers use to hide from the immune system. "Telmisartan has several distinct anticancer effects that, together with targeted therapy, could make tumors more responsive to distinct types of treatments," Curiel said, hinting that the drug's talents may extend beyond PARP inhibitors to chemotherapy and immunotherapy.

Because telmisartan is taken orally, has a long safety track record, and is well-tolerated even by people with normal blood pressure, researchers are already testing it in humans. Two clinical trials at DCC are underway: one in men with metastatic, castration-resistant prostate cancer (the first participant reportedly had an "exceptional response") and another in patients with platinum-resistant ovarian cancer. "We are encouraged by what we are seeing so far," Curiel said, which is probably the understatement of the year for anyone hoping for a cheap, effective cancer boost.