A common blood pressure drug may help a major class of cancer therapies work far better than expected.
A widely prescribed blood pressure drug may have an unexpected second life as a cancer therapy booster.
Researchers at Dartmouth Cancer Center (DCC) have discovered that telmisartan, an FDA-approved medication commonly used to treat hypertension, can significantly enhance the tumor-killing effects of the targeted cancer drug olaparib.
The findings suggest the inexpensive and well-tolerated drug could help expand the benefits of PARP inhibitors to many patients who currently do not respond to these therapies. The study was recently published in The Journal for ImmunoTherapy of Cancer.
“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 Curiel, the study’s senior and lead author.
Expanding the reach of PARP inhibitors
PARP inhibitors, including olaparib, target cancer cells by taking advantage of flaws in their ability to repair damaged DNA. These drugs work especially well in tumors with impaired homologous recombination DNA damage repair, including cancers with BRCA gene mutations. However, many tumors do not have these repair defects, which limits how many patients can benefit. Many cancers also eventually become resistant to PARP inhibitors.
Curiel and colleagues found that telmisartan can increase tumor sensitivity to PARP inhibitors, even in cancers that do not have the DNA repair problems normally linked to PARP inhibitor response.
In preclinical experiments, tumors treated with both telmisartan and olaparib showed more DNA damage than tumors treated with olaparib alone. The combination also activated strong immune-related signals. In particular, it increased production of type I interferons, molecules that help the immune system detect and attack cancer cells.
“This immune activation appears to be a key reason the combination works so well,” Curiel said.
A unique effect among blood pressure drugs
Telmisartan is part of a commonly used class of blood pressure medicines called angiotensin II receptor blockers (ARB). In the DCC study, the cancer-boosting effect was seen only with telmisartan among the ARB drugs tested.
Telmisartan also lowered levels of PD-L1 inside tumor cells. PD-L1 is a protein that helps cancers avoid immune attack, so reducing it may add to the drug’s potential as part of cancer treatment.
“Telmisartan has several distinct anticancer effects that, together with targeted therapy, could make tumors more responsive to distinct types of treatments,” Curiel said. “We showed the improved efficacy with PARP inhibitors in this study, but we also have good data showing that telmisartan improves efficacy of distinct chemotherapy classes and immunotherapies in many other cancer types through related mechanisms.”
Moving quickly to clinical trials
Because telmisartan is taken by mouth, widely used, generally safe, and well tolerated, including in people without high blood pressure, it is a strong candidate for testing in patients. Curiel and colleagues at DCC are already evaluating the approach in two clinical trials.
One trial is testing telmisartan with olaparib in men with metastatic, castration resistant prostate cancer. The first participant had what Curiel described as an exceptional response to the treatment. A second trial is studying the strategy in platinum-resistant ovarian cancer and has just enrolled its first patient.
“We are encouraged by what we are seeing so far,” Curiel said. “Our goal is to determine whether this combination approach can help more patients benefit from greater effectiveness of PARP inhibitors and other cancer treatment classes and potentially overcome resistance to these drugs.”
Reference: “Telmisartan increases olaparib efficacy in homologous recombination proficient tumors by augmenting type I interferon production” by Clare E Murray, Carlos O Ontiveros, Jordan Wentworth, Paige Blinkiewicz, Bernice Leung, Haiyan Bai, Nathaniel Spicer, Anja Holtz, Chris Tanner, Akshaya Balasubramanian, Wenjing Li, Eloise Dray, Weixing Zhao and Tyler J Curiel, 25 March 2026, Journal for ImmunoTherapy of Cancer.
DOI: 10.1136/jitc-2025-012426
Support from the Guyre fund and Gmelich fund at DCC were instrumental in getting these studies completed and the clinical trials launched.
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