Cancer is and always has been one of the biggest hurdles in the medical science field. The cost of clinical trials is often extraordinarily high, making repeated research difficult to conduct. Furthermore, most of these trials are not efficient enough to work in humans, leading to failure when testing outside of smaller animals such as mice. Due to these factors, treating cancer is a sort of balancing act; researchers and doctors want to create the most humane treatment possible without stepping outside the realm of funding constraints.
Despite these challenges, a new tactic is being developed to help defeat breast cancer, one of the most common types of cancer. A light-activated ‘smart’ bomb is currently in development by a husband-and-wife research team from Michigan State University (MSU) in partnership with scientists at the University of California, Riverside. The chemical they are developing is composed of cyanine-carborane salts, a class of boron-rich compounds, and cyanine dyes. The cyanine dyes provide photosensitizing capabilities, while the boron clusters in carborane can generate cancer-killing reactive oxygen species (ROS) under certain conditions.
These “bombs” are used in photodynamic therapy (PDT), a procedure in which a patient receives a photosensitizer (such as cyanine dyes), an ROS generator (a carborane), and some specific wavelength of light. These salts are then spread quickly by the rapidly replicating cancer cells and then activated by a laser or LED light, leading to cellular destruction. The photosensitizer absorbs the light and transfers energy to the oxygen which produces the ROS. This then transmits oxidative damage to the cells and eventually causes them to die.
There are numerous advantages to using photodynamic therapy. The process is minimally invasive as it does not require surgery. The targeting of cells is highly concentrated, leading to little to no collateral damage. The process is easily repeatable, unlike cancer therapy, and no toxicity is left over in the body as there would be with chemotherapy. These cyanine-carborane salts have their advantages over current chemicals used in PDT as well. As stated by Hyllana Medeiros, a researcher at MSU involved in these studies, “Current FDA-approved PDT chemicals remain in other parts of the body, such as the skin, for extended periods of time…after traditional PDT treatment, the patient has to stay in the dark for two-three months because even low levels of light will cause their skin to become blistered and burned.”
Despite all the advancements to this branch of cancer-fighting chemicals, there are still difficulties with the process. Light can only penetrate the skin up to a depth of about a few millimeters, meaning this treatment is strictly ideal for surface-level tumors. Hypoxic tumors that already operate at low-oxygen levels are also less likely to be affected by this type of PDT. Also, despite this technique working in some cases, it is often not a standalone cure—typically being used alongside standard chemotherapy. Lastly, these cyanine-carborane salts aren’t cheap, costing between $5,000 and $20,000 per gram. Although this price is more expensive than the current method of PDT, the lack of side effects and continual research should lead to a more accessible option in the future.
Although this treatment has only been tested on mice thus far, it has been proven to work in many cases, even against aggressive breast cancers. More research and development are required to bring this technique to its fullest potential; however, the current results are pointing to a promising future.
