Innovative prostate cancer treatment awarded $1.7m research grant

Scientists researching an ‘ancient virus’ treatment for metastatic prostate cancer have been awarded $1.7 million by the US Department for Defense.

Oncology expert Charles Spruck’s laboratory at Sanford Burnham Prebys in California, is focused on developing new, effective, and non-toxic treatments for patients with advanced cancers.

Now the associate professor and his team will use the Department of Defense grant to advance a novel therapeutic approach to treating prostate cancer called viral mimicry, that utilises ancient viruses embedded in our genomes to trick the body into thinking it has an infection.

The hope is to have a clinic-ready drug available within the next three years.

Dr Spruck explained: “In viral mimicry, the body thinks there’s an infection, which kicks the immune system into high gear.  With the immune system activated, cancer cells are more responsive to treatment, and tumour growth slows. All of this can happen without triggering treatment resistance, which could be a huge benefit for treating prostate cancer.”

Prostate cancer is the second most diagnosed cancer in men worldwide and the fifth leading cause of cancer death. Mainly affecting men over 50, the risk of developing it increases with age. The most common age to be diagnosed is between 70 and 74 years.

According to the World Health Organisation, there were an estimated 1.4 million new cases of prostate cancer and more than 375,000 deaths from the disease in 2020 alone.

Currently there is no cure for metastatic prostate cancer, but it can be treatable for some time. Many patients outlive their prostate cancer, even those with advanced disease.

Charles Spruck

Dr Spruck said: “Many cases of prostate cancer are treatable, so people don’t think of it as a major public health issue. But when prostate cancer becomes metastatic or resistant to therapy – such as hormone therapy – it can ultimately become a fatal disease. One of the benefits of this approach is that it works in a completely different way, so it’s not as susceptible to resistance.”

The new approach takes advantage of a bizarre evolutionary feature of our genomes called endogenous retroviruses (ERVs).

These are small sequences in our genomes left behind by viruses that infected our ancient ancestors. ERVs have been found in the genomes of early humans, such as Neanderthals, but are thought to have first emerged in animals hundreds of millions of years ago.

Unlike regular viruses, ERVs do not make us sick. Instead, they bounce around our genomes and help control gene expression.

“ERVs are inactive, so they don’t produce proteins the way regular genes do,” Dr Spruck said. “In this study, we discovered that we can reactivate these viruses selectively in cancer cells and essentially fool the body into thinking it needs to trigger an immune response against the tumour.”

Dr Spruck’s team has already discovered a potential drug that can induce viral mimicry in prostate cancer cells. However, the drug is not potent or selective enough to enter the clinic.

One of the goals of their project is to develop more potent compounds that can induce viral mimicry, which could lay the foundation for tomorrow’s prostate cancer treatments.

Dr Spruck said: “Something very exciting about this work is that it has the potential to move to the clinic extremely quickly. We hope to have a drug ready for the clinic within three years.”

In addition to prostate cancer, the viral mimicry approach could be effective across a range of treatment-resistant cancers. The researchers are already exploring the approach in ER+breast cancer, in which up to 50% of patients experience a relapse due to treatment resistance.

“We initially discovered viral mimicry in breast cancer, and we suspected it could work in other cancers,” Dr Spruck said. “This project is helping us see how far we can take this unique approach, and I’m confident we’ll be able to apply it more broadly in the future as we continue to learn more about how it works.”