Common Blood Pressure Medication Shows Promise in Cancer Treatment

An inexpensive blood pressure medication could become an unexpected ally in cancer treatment, according to a promising preclinical study from Dartmouth Health researchers. Telmisartan, an FDA-approved drug commonly prescribed for hypertension and cardiovascular risk reduction, has demonstrated potential to enhance the effectiveness of certain cancer therapies.

The study, published in the Journal for ImmunoTherapy of Cancer, found that telmisartan significantly improved how well cancer cells responded to olaparib, a targeted therapy known as a PARP inhibitor. This combination appears to work by causing more extensive damage to cancer cells’ DNA, making them more recognizable to the immune system.

“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 lead researcher Tyler J. Curiel, MD, a clinical researcher at Dartmouth Health in New Hampshire.

The research team discovered that the combination therapy increased production of type I interferons, molecules that help the immune system identify and attack cancer cells. Telmisartan was also found to reduce levels of PD-L1, a protein that helps tumor cells evade immune detection.

“This immune activation appears to be a key reason the combination works so well,” Curiel explained.

Notably, the researchers found that this anti-cancer effect appears unique to telmisartan. Other medications in the same class—known as angiotensin II receptor blockers (ARBs)—did not demonstrate the same cancer-fighting properties.

The discovery has significant implications for cancer treatment approaches. “Telmisartan has several distinct anti-cancer effects that, together with targeted therapy, could make tumors more responsive to distinct types of treatments,” said Curiel. “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.”

Medical experts not involved in the research have responded cautiously but optimistically. Joshua G. Cohen, MD, medical director of the Gynecologic Cancer Program at City of Hope Orange County in Irvine, California, noted, “While there were past concerns that ARBs might increase cancer risk, large studies have shown they do not, and are considered safe for patients who need them.”

However, the research does have limitations that should temper expectations. The study primarily relied on laboratory models and animal testing rather than human clinical trials. “At this stage, the idea is still very early in development, and the evidence comes primarily from laboratory studies, not studies in people,” Cohen emphasized.

The findings also suggest the approach may not work equally well against all cancer types. Telmisartan appeared most effective against tumors with existing DNA damage, which means it may not work as well for cancers without these defects. Additionally, many cancers develop resistance to olaparib over time, potentially limiting long-term effectiveness.

No data on long-term outcomes or survival rates are currently available, underscoring the need for comprehensive clinical trials. “Much more research—including clinical trials—is needed to determine whether combining telmisartan with PARP inhibitors is safe or effective for treating ovarian cancer,” Cohen cautioned. “Patients considering these medications together should speak with their cancer care team, who can help them understand what is known, what remains uncertain and what is safest for their individual situation.”

The Dartmouth researchers are already moving forward with human testing. Two clinical trials are currently underway—one examining the drug combination in men with advanced prostate cancer that has stopped responding to hormone therapy, and another, just beginning enrollment, focusing on women with ovarian cancer that no longer responds to platinum-based chemotherapy.

“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.”

The researchers noted that telmisartan is generally considered safe and well-tolerated based on its established clinical use for cardiovascular conditions, which could accelerate its potential adoption for cancer treatment if clinical trials prove successful.