MIT chemists have made it possible that three or more chemotherapeutic drugs can now be constructed to form a nanoparticle for targeted cancer therapy.
Cancer needs no introduction; its occurrence has increased by changes in lifestyle and longevity. It is characterized by the uncontrolled growth and spread of abnormal cells and is responsible for several deaths worldwide. Cancer may occur at any part of the body and can spread to other parts of the body if not detected at an early stage.
Conventional cancer therapy includes surgery, hormone therapy, radiation and chemotherapy. Except surgery all other conventional cancer therapy is non-specific that is to say that these treatments while being toxic to cancer cells are equally toxic to normal cells. The non-specific introduction of these therapeutic drugs into the body is not only toxic to normal tissue but also limits the therapeutic dose affecting the cancer cells. Conventional cancer therapy also poses adverse side effects such as weakness, nausea, hair loss, and organ dysfunction.
Nanoparticles as cancer therapy
Nanoparticles have gained considerable attention as therapeutic vectors for drug delivery in the past 3 or more decades. Their wide range of sizes ranging between 1-1000nm and the use of different materials as nanoparticles all encourages its use as a drug delivery vector. The nanoparticle may be constructed of polymers, lipids, carbon, silicon, inorganic materials and biological materials. The first nanoparticle under clinical trial for anti cancer drug delivery was a liposomal encapsulated doxorubicin nanoparticle in 1980s and was commercially available in 1995.
Advantages of nanoparticles is their prolonged circulation time, enhanced solubility of hydrophobic drugs, minimizes non specific uptake, improves intracellular penetration and allows specific cancer cell targeting with reduced side effects.
Nanoparticle administration still faces challenges concerning stability, solubility and pharmacokinetic properties. Toxicity of material, shelf life, leakage and aggregation are certain other concerns over nanoparticles being used as drug delivery vectors. Nanoparticles need to be optimized for size, shape, drug encapsulation efficacy, desired drug release profiles, distribution and cost.
Breakthrough by MIT chemists
Nanoparticles commercially available for cancer therapy are constructed with material that encapsulates just one or two drugs at the most. In this method the drugs are attached and encapsulated in the nanoparticles. The MIT chemists who undertook this research designed a novel nanoparticle with the help of three cancer therapy drugs forming its structure. The nanoparticles were tested in mice and successful therapy reported by the shrinking of tumours. The study was reported in the Sept 14 issue of Journal of the American Chemical Society.
The scientists also noted that of the three drugs used one drug changed its mechanism of action probably due to structural changes during the construction or release from nanoparticle. The three drugs used were cisplatin, doxorubicin and camptothecin. While doxorubicin and camptothecin acted as they usually do, cisplatin behaved like oxaliplatin which is a platinum based drug that also acts by binding to DNA but brings about its destruction by a different mode of action.
This new nanoparticle production technique by MIT researchers uses the three drug molecules as building blocks of the nanoparticle and is able to precisely control the specific structure. The advantage of this approach lies in its ability to deliver drugs that cannot be encapsulated by traditional methods. These nanoparticles along with combination chemotherapy must work efficiently to fight against cancer.