There are more than 12 million new cases of cancer diagnosed worldwide each year. Some types of cancer can be treated relatively well with established treatments. However, there are some forms of cancer that don’t respond to these approaches, and drug delivery remains a key challenge.
New and innovative methods of drug delivery are currently being explored. These include the use of microparticles as carriers of anticancer agents. These microparticles are injected into the bloodstream and guided to the tumor by magnetic field for targeted drug delivery.
Professor Paula T. Hammond, head of MIT’s Department of Chemical Engineering, spoke about this subject at a recent TED talk conference. Her team has engineered a nanoparticle one-hundredth the size of a human hair that, they say, can treat the most aggressive, drug-resistant cancers.
The goal for the MIT chemists was to create a superweapon that could travel through the bloodstream and penetrate the tumor tissue. For this to be possible, the nanoparticle would have to be small enough to be taken up inside the cancer cell.
Here is how Professor Hammond described the process of building this nanoparticle:
“First, let's start with the nanoparticle core. It's a tiny capsule that contains the chemotherapy drug. This is the poison that will actually end the tumor cell's life. Around this core, we'll wrap a very thin, nanometers-thin blanket of siRNA. This is our gene blocker.”
Small interfering RNA (siRNA) are a set of molecules that can be used to turn off a specific gene inside a cell. Scientists have been very excited about the huge clinical potential of these gene blockers in diagnostics and drug delivery.
“Because siRNA is strongly negatively charged, we can protect it with a nice, protective layer of positively charged polymer. The two oppositely charged molecules stick together through charge attraction, and that provides us with a protective layer that prevents the siRNA from degradation in the bloodstream.”
Our bodies have cells that reside in the bloodstream and attack anything that doesn’t belong. Hammond and her team needed to devise a way of deploying the nanoparticle without meeting this fate. Their solution was to add one more negatively charged layer around the nanoparticle, which serves two purposes:
- It creates a cloud of water molecules around the nanoparticle that gives us an invisibility cloaking effect.
- It contains molecules which bind to the tumor cell. Once inside the cancer cell, the nanoparticle is ready to deploy.
Destroy the Tumor
With the hard part done, this is what Professor Hammond says happens next:
“With the siRNA deployed, the cancer cell is left defenseless. The chemotherapy drug comes out of the capsule and destroys the tumor cell cleanly and efficiently. If a sufficient amount of gene blockers are used, it will be possible to address many different kinds of mutations and clear out any remaining tumors, without leaving anything behind.“
So, that is the theory. But how well does it work in practice?
According to the MIT researcher and educator, the nanoparticles have been tested in animals with a highly aggressive form of triple-negative breast cancer. They found that not only did the tumors stop growing, they actually decreased in size and were eliminated in some cases.
Hammond says this approach can be personalized by adding different layers of siRNA and by putting different drugs into the nanoparticle core. This is supported by a recent report on Nanomedicine has a growing presence in all therapeutic areas, exhibiting a perceptible and extensive impact in the treatment and diagnosis of certain diseases.
It is clear that engineering at a molecular level can provide some exciting new ways to fight cancer, and it will be interesting to see where Professor Hammond’s superweapon goes from here. But this is just one in a number of exciting clinical trials that have made headlines in recent weeks.
Yesterday, researchers at UT Southwestern Medical Centre revealed some interesting findings on Stereotactic Body Radiation Therapy (SBRT). Their five-year study found SBRT to be more effective than traditional approaches, with a 98.6 percent cure rate.
In another study by Bristol-Myers Squibb, more than one-third of advanced melanoma patients were treated with cancer immunotherapy agents. The data showed a 5-year survival rate for 34% of the patients.
Fueled by clinical trials like the ones above, the global advanced drug delivery market is set to reach $227.3 billion by 2020.
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