Reported in ACS Nano, researchers have developed a nanoparticle therapy to target lymph node metastases for destruction, before they can cause cancer at other locations.
Metastasis, in which cancer cells break free from the primary tumour and form tumours at other sites, worsens the outcome for many cancer patients. The lymph nodes, which are glands of the immune system located throughout the body, are usually the travelling cells’ first destination. Now, researchers have developed a strategy to target the lymph node metastases with iCluster, the nanoparticle delivery tool – does this mean nanoparticle therapy could help improve tumour therapy?
Targeting lymph node metastases
Soon after a patient is diagnosed with cancer, they typically undergo lymph node biopsies to determine if their cancer has spread. However, such a surgical procedure can cause pain, infection and other problems.
Studies have shown that cancer cells travel from tumours to specific lymph nodes primarily through tiny vessels called lymphatics, which carry immune cells and fluid rather than blood. So, a treatment that could be injected into the bloodstream, enter a tumour and then pass through the lymphatics could possibly treat metastases.
Hong-Jun Li, Jin-Zhi Du and colleagues had previously developed a nanoparticle delivery tool, called iCluster, that travels through the bloodstream to a tumour. This is the nanoparticle therapy aspect, whereby a large cluster of nanoparticles, and the acidic environment of the tumour causes iCluster to disassemble into its smaller components, which can penetrate deep into tumours and deliver chemotherapies.
Injecting nanoparticle therapy
But the team wondered whether these smaller nanoparticles could also pass through the lymphatics that connect the tumour to lymph nodes.
The researchers injected iCluster, labelled with a red dye, into the bloodstream of mice with transplanted tumours. By fluorescent imaging, they observed that small nanoparticles carrying the chemotherapy drug, cisplatin, could indeed pass through the lymphatics from the tumour to adjoining lymph nodes.
In another experiment, the researchers treated mice with primary tumours before metastasis with iCluster, and a couple of days later, surgically removed their primary tumours, similar to what would be done for cancer patients. About 40% of the treated mice were still alive 110 days later.
That is in contrast to the untreated mice – all of them died from metastases within 51 days of surgery. Then, the team tested the therapy on mice that already had metastases. The iCluster-treated mice lived longer, and upon autopsy, had far fewer tumours than untreated mice.