Cancer has topped most charts among the deadliest diseases affecting humankind all over the globe, in 2020 it caused nearly 10 million deaths. Although there are techniques such as chemotherapy, surgery and radiation which aim to eradicate cancer or tumor, such procedures may be associated with high toxicity and may not resolve the problem in the long run.
But there’s good news on the cancer research front, scientists are creating a novel therapeutic approach employing gold (Au) complexes to fight cancer. This advance presents a system unifying chemotherapy, phototherapy, and activation of immunity.
What Are Gold (Au) Complexes?
In this method, scientists have focused on Au(I) complexes of gold containing compounds. Gold molecules attack the cancerous cells without damaging the surrounding healthy tissues. The gold complexes are formulated in a way to inhibit proteins abundant in cancer such as thioredoxin reductase (TrxR) that promote cell growth. Due to the gold complex binding TrxR, the tumor cells become more susceptible to treatment.
Combining Chemo-Phototherapy for Maximum Impact
One of the critical ways in which this research is unique is the use of chemotherapy and phototherapy in the treatment at the same time. Let’s go through them one step at a time.
- Chemotherapy employs chemical agents to control the aggressiveness and spread of cancer cells. Unfortunately, it also affects healthy cells: hence the adverse effects such as weakness, nausea, hair loss, etc.
- Phototherapy does not use chemicals to kill cancer cells; instead, it uses light to ‘switch on’ special compounds that are able to kill the cancer cells. These compounds can, once activated by light, generate reactive oxygen species (ROS) that kill the cancer cells.
- Usually, this causes lower adverse effects than chemotherapy, however, it has its own complications. Most photosensitizers are either short-lived or lose activity in vivo due to incorporation into aggregates (aggregation-caused quenching, ACQ).
- In order to address this challenge, the authors resorted to the use of aggregation-induced emission luminogens (AIEgens). What’s more, when these same constituents aggregate, they are actually activated: the contrary of efficacy.Due to the light excitation of the gold AIEgens, ROS is produced, which in turn delivers the cytotoxic effect on malignant cells.
How the Immune System Gets Involved
One of the most stimulating elements of this types of therapy is that it does not simply help destroy cancer cells. It also harnesses a person’s immune system to fight the cancer. When ROS are used by gold complexes to eradicate the tumor cells, dying cells secrete so-called damage-associated molecular patterns (DAMPs). Such signals are recognized by the immune system with the purpose of killing the tumor cells and so establish a memory response.
Diamo-termic cytotoxicity is the process in simple terms which is referred to as immunogenic cell death (ICD) helps the body both see and eliminate the cancer cells even if it has stopped aggressive treatment with the cure. This is to say that the disease would still be fought off by the body, which in effect would further lessen the risks of reigning.
What Makes Gold Complexes the Next Generation of Cancer Treatment
The compounds of gold studied by the research group were sufficient to lead to tumor cell death and have little or no effect on normal tissues. In terms of treatment, one particular gold complex known as complex 4 was remarkably effective. This compound was not only capable of specifically destroying malignant cells but also offered impressive imaging properties. This meant that the medicine could be utilized to treat cancer and simultaneously evaluate the effectiveness of treatment with a clearer picture through an imaging fusion.
The gold complex treatment showed several key benefits:
- Selective Targeting: Cancer cells are attacked but surrounding normal tisues are left rather intact.
- Reduced Side Effects: The acute toxicity of photo-chemotherapy incorporated in AIEgens is lower than that of systemic chemotherapy plus phototherapy AIEgens used separately.
- Immune Boost: Its purpose is to activate the immune system to attack the cancer cells even after the treatment is over, thus preventing the recurrence of cancer.
Looking Ahead: What’s Next?
Although this research is still at an early stage, the results are encouraging. Further studies will target more gold complexes with an aim of developing these complexes even further such that their efficacy can be applied to more cancer types. The researchers are also focused on the modification of the gold complexes for the near-infrared light absorption so that the treatment can be done with deep tissue penetrating cancerous tumors that are difficult to access.
In the near future, we will probably witness gold containing chemo plus phototherapy combining with immunotherapy for treating cancer becoming a norm. This active, multi-targeted strategy should provide patients with a better and less invasive treatment than the one they usually have today.
Conclusion
The use of gold-based Au(I) complexes for treatment of cancer is a novel therapeutic approach in cancer management. The incorporation of chemotherapy, phototherapy, and modulation of immunity, this mode of therapy may enhance most patients’ outcomes. Although it is clear that such an approach requires further validation, it is already possible to imagine a more effective treatment of cancer that will be safer for patients.
