Blood Pressure Drug Telmisartan Supercharges Cancer-Fighting Power of PARP Inhibitors

A common, affordable blood pressure medication may be on the verge of transforming how a major class of cancer drugs is used. Researchers at Dartmouth Cancer Center published findings in The Journal for ImmunoTherapy of Cancer showing that telmisartan — an angiotensin II receptor blocker (ARB) prescribed for hypertension — can significantly amplify the cancer-fighting power of olaparib, a PARP inhibitor used in targeted cancer therapy.

PARP inhibitors like olaparib work by exploiting weaknesses in the DNA repair machinery of certain cancer cells. They are most effective against tumors carrying BRCA gene mutations, which limits their use to a subset of patients. Tumors can also develop resistance over time, further narrowing who benefits. The Dartmouth team found that telmisartan can sensitize tumors to olaparib even when those BRCA-related DNA repair defects are absent, potentially opening the treatment to a far broader patient population.

In preclinical experiments, the drug combination increased DNA damage in cancer cells while simultaneously triggering a stronger immune response. Telmisartan boosted production of type I interferons — signaling molecules that alert the immune system to attack cancer cells. It also reduced intracellular levels of PD-L1, a protein tumors use to evade immune detection. These effects were unique to telmisartan among tested ARBs, suggesting a mechanism specific to this molecule rather than its drug class broadly.

The research team also reports preliminary data showing telmisartan enhances the efficacy of distinct chemotherapy classes and immunotherapies across multiple cancer types, hinting at wide therapeutic applicability beyond PARP inhibitor combinations.

Because telmisartan is oral, inexpensive, well-tolerated — even in people without hypertension — and already FDA-approved, it is particularly well-positioned for rapid clinical translation. Human clinical trials combining telmisartan with olaparib are already underway. Caveats remain: preclinical results do not always translate to humans, and trial outcomes are pending.