Cancer treatments are often referred to as cocktails. A mixture of medications that, when combined, offer more effective treatment than a single medication alone. There are a number of different treatment options for prostate cancer depending on the type and stage of the disease. This is important because for many when cancer cells spread from the prostate gland, treatment options change. As well, treatment may become less effective as cancer becomes resistant to a single agent after several “therapeutic cycles.” This resistance can lead to recurring and progressive disease, and a decreased survival rate.
Combination therapy is not new in the treatment of cancer. But new research on how these medications can best be combined has resulted in improved technologies for administering drug treatments. A study from China on nanoparticles describes how new technologies in drug development and administration can improve therapeutic outcomes.
The role of nanoparticles
Nanoparticles are microscopic particles that have a number of unique properties in addition to their size that make them viable for delivery of a drug or drug-like molecules. They can serve as a bridge or transport agent for drug-like molecular structures helping treatments to reach a specific molecular target and increase the effectiveness of the transported drug. The goal is to better target and kill the cancer cells while leaving healthy cells, nerves, and tissue adjacent to cancer cells alone.
Albumin is a protein that is present in egg whites and milk, and also occurs naturally in the human body in blood serum (human serum albumin, or HSA). It is soluble in water and coagulates with heat. The new study from the Medical School of Nanjing University in China demonstrates that encapsulating a chemotherapy drug in albumin nanoparticles creates an improved platform to deliver the medications because it allows more of the chemotherapy target to reach the target cancerous cells.
The chemotherapy drugs used in the study need to be activated by photothermal (PTT) or photodynamic (PDT) therapy to be useful. PTT agents attack cancer using heat. To reach a high temperature they are activated with a laser. PDT agents are activated by light of a specific wavelength. The PDT agents combine with oxygen to create a toxic substance that attacks cancer cells. These drugs are hydrophobic, not soluble in water and are easily eliminated from the body.1 When encapsulated in HSA nanoparticles their solubility is increased. These new nanoparticles combined with irradiation have proven more effective in killing cancer cells than any single therapeutic agent alone.
Treatments tested in mice
As with other cancer studies, new approaches to treatment are tested in mice whose systems are not unlike those of humans. One of the interesting findings was that the nanoparticles landed in the tumor regions within 48 hours of the mice being injected with medication, and the nanoparticle location was verified through imaging technology.
This finding may prove beneficial in developing a future diagnostic tool for locating prostate cancer cells. Additionally, the combined therapy (irradiation and nanoparticle encapsulated chemotherapy drug) inhibited tumor growth in the mice. The ability to inhibit tumor growth was better than either chemotherapy or nanoparticles by themselves. The researchers believe this may be due to improved permeability and ability of the nanoparticles to help the chemotherapy drug accumulate in tumor cells instead of being distributed more in the region of the tumor.2
Why does this matter?
Combination therapy using nanoparticles holds promise for improving the effective treatment and resulting survival of patients with prostate cancer. At least as demonstrated through an animal model, nanoparticle drug delivery enhances therapeutic effectiveness and reduces side effects of drug payloads by improving pharmacokinetics; the way that the drugs move into, through, and out of the body.3
This research is an example of a way oncology researchers, scientists, chemists, and engineers are working together to find new therapeutic approaches and to solve for chemoresistance of cancerous cells. These approaches may one day replace traditional intravenous chemotherapy where healthy tissues and cancer cells are both exposed to chemotherapeutic agents.3 While it is still early to know if these same effects will be observed in humans, these results suggest that there may be multiple benefits to using nanoparticles in cancer diagnostics and therapeutics.
Malhas, A. Packing Anti-cancer Agents within Albumin Boosts Combo Therapy Effectiveness Against Prostate Cancer, Study Shows. Published November 3, 2017. https://prostatecancernewstoday.com/2017/11/03/human-serum-albumin-boosts-combo-anti-prostate-cancer-therapy/. Accessed online November 28, 2017.
Lian H, Wu J,. Self-assembled albumin nanoparticles for combination therapy in prostate cancer. Int J Nanomedicine. 2017;12:7777-7787. Published October 24, 2017.
https://www.dovepress.com/self-assembled-albumin-nanoparticles-for-combination-therapy-in-prosta-peer-reviewed-article-IJN. Accessed online November 28, 2017.
Hu CM, Aryal S. Nanoparticle-assisted combination therapies for effective cancer treatment. Ther Deliv. 2010;1(2):323-34. Published in 2010 on future-science.com website. http://nano.ucsd.edu/~l7zhang/publications/37-TD.pdf. Accessed online November 28, 2017.