Cancer-associated high platelet levels have been linked to poor clinical outcomes in cancer patients, yet the underlying mechanism for this phenomenon has remained largely unknown. Moreover, cancers cells have the ability to develop resistance towards a single anti-cancer therapy, necessitating the need for specific combination therapies.

Attributes such as these are the factors that make cancer so difficult to treat. Fortunately, new research may have found a solution to this - an essential clotting agent that promotes cellular healing, the seemingly harmless platelet cell.

“Over the years, it has become appreciated that platelets are doing more than just clotting,” says oncologist Zihai Li, senior author of the research paper.

Platelets shield cancer cells from immunity

With results published earlier this month, a team at the Medical University of South Carolina successfully proved the hypothesis that platelet cells promote cancer growth and resistance to anti-cancer therapy. Platelet cells had encouraged cancer growth by dampening the host immunity system.

Using a series of tests on mice with skin cancer, a team of researchers were able to identify the link between platelet and cancer cells.

The protein GARP on the surface of platelet cells was found to activate an immunity suppression cascade (the GARP-TGFβ axis). As such, genetically-modified mice without GARP were found to respond better to adoptive T cell therapy when it comes to controlling skin cancer.

Meanwhile, normal mice with skin cancer that were treated with adoptive T cell and dual-antiplatelet therapy were found to have improved survival rates.

In essence, platelet cells provide cancer cells with an invisibility cloak from the immune system. By eliminating or modifying platelet cells, this invisibility cloak was effectively removed, allowing the immune system to home in on cancer cells.

Future therapeutic implications

Short term implications of these research findings include the addition of a new combination agent for anti-cancer therapy. Anti-platelets used in conjunction with anti-cancer drugs may offer a cheap, readily-available and effective treatment for cancer patients as quickly as today.

In fact, early clinical trials have already started to assess the effectiveness of this therapeutic combination. A clinical trial will be carried out by Li and his group to see if combination therapy with antiplatelet drugs could improve existing cancer treatment.

“We can test simple, over-the-counter antiplatelet agents to really improve immunity and make a difference in how to treat people with cancer,” says Li.

While the current research findings are limited towards skin cancer, there is hope that the findings can be expanded towards treating other forms of cancer in the future. Moreover, this research has led towards a better understanding of cancer cells, and hopefully would ultimately lead to the development of new therapies or implementation of existing therapies in the battle against cancer.

While it is still uncertain if anti-platelets can be used as adjuvant cancer therapy, this treatment modality does show a great deal of promise. Much of this has to do with anti-platelet agents being readily available over the counter, cheap and well understood in terms of its action profile and side effects. MIMS

Read more:
NUS scientists develop new dual-mode contrast to enhance liver cancer imaging
Immunotherapies might hasten tumour growth instead, suggests cancer researchers
Epigenetic drugs: The promise of future precise cancer treatments