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Researchers are experimenting with new ways to design tiny particle treatments for cancer
Nanoparticles are the future of medicine.
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When you hear the word ānanomedicine,ā it might call to mind scenarios like those in the 1966 movie āFantastic Voyage.ā The film portrays a medical team shrunken down to ride a microscopic robotic ship through a manās body to clear a blood clot in his brain.
Nanomedicine has not reached that level of sophistication yet. Although scientists can generate nanomaterials smaller then several nanometers ā the ānanoā indicating one-billionth of a meter ā todayās nanotechnology has not been able to generate functional electronic robotics tiny enough to inject safely into the bloodstream. But since theĀ concept of nanotechnologyĀ was first introduced in the 1970s, it has made its mark in many everyday products, including electronics, fabrics, food, water and air treatment processes, cosmetics and drugs. Given these successes across different fields, many medical researchers were eager to use nanotechnology to diagnose and treat disease.
I am aĀ pharmaceutical scientistĀ who was inspired by the promise of nanomedicine.Ā My labĀ has worked on developing cancer treatments using nanomaterials over the past 20 years. While nanomedicine has seen many successes, some researchers like me have been disappointed by itsĀ underwhelming overall performanceĀ in cancer. To better translate success in the lab to treatments in the clinic, we proposed aĀ new way to designĀ cancer drugs using nanomaterials. Using this strategy, weĀ developed a treatmentĀ that was able to achieve full remission in mice with metastatic breast cancer.
WHAT IS NANOMEDICINE?
Nanomedicine refers to the use of materials at the nanoscale to diagnose and treat disease. Some researchers define nanomedicine as encompassing any medical products using nanomaterials smaller than 1,000 nanometers. Others more narrowly use the term to refer to injectable drugs using nanoparticles smaller than 200 nanometers. Anything larger may not be safe to inject into the bloodstream.
Several nanomaterials have been successfully used in vaccines. The most well-known examples today are theĀ Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines. These vaccines used a nanoparticle made of of lipids, or fatty acids, that helps carry the mRNA to where it needs to go in the body to trigger an immune response.
Researchers have also successfully used nanomaterials in diagnostics and medical imaging.Ā Rapid COVID-19 testsĀ andĀ pregnancy testsĀ use gold nanoparticles to form the colored band that designates a positive result.Ā Magnetic resonance imaging, or MRI, often uses nanoparticles as contrast agents that help make an image more visible.
Several nanoparticle-based drugs have been approved for cancer treatment.Ā Doxil (doxorubicin)Ā andĀ Abraxane (paclitaxel)Ā are chemotherapy drugs that use nanomaterials as a delivery mechanism to improve treatment efficacy and reduce side effects.
CANCER AND NANOMEDICINE
The potential of nanomedicine to improve a drugās effectiveness and reduce its toxicity is attractive for cancer researchers working with anti-cancer drugs that often have strong side effects. Indeed,Ā 65% of clinical trials using nanoparticlesĀ are focused on cancer.
The idea is that nanoparticle cancer drugs couldĀ act like biological missilesĀ that destroy tumors while minimizing damage to healthy organs. Because tumors have leaky blood vessels, researchers believe this would allow nanoparticles toĀ accumulate in tumors. Conversely, because nanoparticles can circulate in the bloodstream longer than traditional cancer treatments, they could accumulate less in healthy organs and reduce toxicity.
Although these design strategies have been successful in mouse models, most nanoparticle cancer drugs haveĀ not been shownĀ to be more effective than other cancer drugs. Furthermore, while some nanoparticle-based drugs can reduce toxicity to certain organs, they may increase toxicity in others. For example, while the nanoparticle-basedĀ DoxilĀ decreases damage to the heart compared with other chemotherapy options, it can increase the risk of developingĀ hand-foot syndrome.
IMPROVING NANOPARTICLE-BASED CANCER DRUGS
To investigate ways to improve how nanoparticle-based cancer drugs are designed, my research team and IĀ examined how wellĀ five approved nanoparticle-based cancer drugs accumulate in tumors and avoid healthy cells compared with the same cancer drugs without nanoparticles. Based on the findings of our lab study, we proposed that designing nanoparticles to beĀ more specificĀ to their intended target could improve their translation from animal models to people. This includes creating nanoparticles that address the shortcomings of a particular drug ā such as common side effects ā and home in on the types of cells they should be targeting in each particular cancer type.
Using these criteria, we designed aĀ nanoparticle-based immunotherapyĀ for metastatic breast cancer. We first identified that breast cancer has a type of immune cell that suppresses immune response, helping the cancer become resistant to treatments that stimulate the immune system to attack tumors. We hypothesized that while drugs could overcome this resistance, they are unable to sufficiently accumulate in these cells to succeed. So we designed nanoparticles made of a common protein called albumin that could deliver cancer drugs directly to where these immune-suppressing cells are located.
When we tested our nanoparticle-based treatment on mice genetically modified to have breast cancer, we were able to eliminate the tumor and achieve complete remission. All of the mice were still alive 200 days after birth. Weāre hopeful it will eventually translate from animal models to cancer patients.
NANOMEDICINEāS BRIGHT BUT REALISTIC FUTURE
The success of some drugs that use nanoparticles, such as theĀ COVID-19 mRNA vaccines, has prompted excitement among researchers and the public about their potential use in treating various other diseases, including talks about a futureĀ cancer vaccine. However, a vaccine for an infectious disease isĀ not the sameĀ as a vaccine for cancer. Cancer vaccines may require different strategies to overcome treatment resistance. Injecting a nanoparticle-based vaccine into the bloodstream also has different design challenges than injecting into muscle.
While the field of nanomedicine has made good progress in getting drugs or diagnostics out of the lab and into the clinic, it still has a long road ahead. Learning from past successes and failures can help researchers develop breakthroughs that allow nanomedicine to live up to its promise.
This article is republished fromĀ The ConversationĀ under a Creative Commons license. Read theĀ original article.