A recent breakthrough study published in Nature, March 2025 provides new mechanistic insights into how the long-known drug, aspirin, may prevent cancer cells spreading (metastasising). The researchers based in Cambridge UK discovered a remarkable link between aspirin and the anti-cancer T cell immune response in mice.
T cells against cancer
T cells are key immune cells which are not only important in the body's immune defence against harmful pathogens but are also capable of killing cancer cells. When cancer cells break free from primary tumours and spread to elsewhere in the body, they become particularly vulnerable to immune attack. Supercharging the T cell response against cancer cells is therefore an attractive therapeutic axis to exploit.
Many cancer immunotherapies successfully harness the power of T cell responses against cancer cells including CAR-T cell therapy, cancer vaccines and checkpoint inhibitor therapy such as anti-PD-1 or anti-PD-L1 antibody treatment.
However, despite advances in treatments, patients can still suffer cancer metastasis after receiving immunotherapy and there is a need for further understanding within this area.
Multiple effects of aspirin
The small molecule drug used in the study, aspirin, is an inhibitor of the enzyme cyclooxygenase 1 (COX-1). Commonly used as an off-the-shelf product direct to the consumer, aspirin reduces pain. It is also known to help prevent blood clots and cardiac diseases by reducing the platelet-derived clotting factor, thromboxane A2 (TXA2). More recently, studies have even identified an association between aspirin treatment and the reduction of cancer metastasis.
However, how aspirin leads to the observed decrease in cancer metastasis was unclear.
A new way to promote T cell immune attack?
By conducting experiments in mouse models, the scientists identified that if mice lacked the gene which encodes the protein ARHGEF1, primary cancers spread to the lungs and liver less frequently. The researchers then uncovered that ARGHEF1 protein suppresses T cell activity and that ARGHEF1 was "switched on" when T cells were exposed to TXA2.
As aspirin was known to reduce TXA2, this prompted further investigation into whether aspirin could limit the T cell suppression. Ultimately, using mouse melanoma models, the researchers found that cancer metastasis was less frequent in mice treated with aspirin.
Taken together, the key conclusions from the study are:
- TXA2 suppresses T cell immunity to cancer metastasis
- The T cell suppression was in an ARHGEF1-dependent manner
- Using aspirin to reduce TXA2 released T cells from suppression, boosting anti-cancer immunity
Future outlook
This exciting research is already sparking interest and further investigation into the mechanistic pathway is ongoing. This study also serves as a reminder that there may be more to discover from experiments using existing drugs, highlighting the potential of:
- repurposing existing drugs; and
- using known drugs to identify novel mechanisms and therapeutic targets within a mechanistic pathway.
From an intellectual property perspective, is it worth investing time and resources into uncovering new discoveries using known drugs?
The potential of new patent protection for known drugs
Moving to the patent world, protection can be obtained for uses of a known drug, providing that the new use is novel and inventive. From a UK and European perspective, this can be achieved by so-called second medical use claims.
Examples of patentable new therapeutic purposes include:
- The use of a known drug for the treatment of a new disease;
- The use of a known drug for the treatment of a known disease, using a new therapeutic method such as a new:
- dosage regime; or
- administration method;
- The use of a known drug for the treatment of a known disease, using a new formulation;
- Targeting a new patient population; or
- The use of a known drug for the treatment of a known disease, where the drug is administered as a new combination therapy with an additional agent.
J A Kemp LLP acts for clients in the USA, Europe and globally, advising on UK and European patent practice and representing them before the European Patent Office, UKIPO and Unified Patent Court. We have in-depth expertise in a wide range of technologies, including Biotech and Life Sciences, Pharmaceuticals, Software and IT, Chemistry, Electronics and Engineering and many others. See our website to
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
