These heat-activated ‘grenades’ deliver drugs directly into cancer cells

Researchers have come up with a new way to deliver cancer-fighting drugs: So-called heat-sensitive “grenades” that serve as couriers, delivering molecules directly into tumor cells and sparing healthy tissue from the potential ill-effects of the potent medications.

As University of Manchester professor of nanomedicine Kostas Kostarelos was set to explain Monday at the National Cancer Research Institute (NCRI) Cancer Conference in Liverpool, he and his colleagues have been developing liposomes—small structures made from cell membranes that are capable of delivering the drug payload directly to cancer cells.

To that end, they have completed two new studies that bring these liposomes one step closer to completion by showing how they were able to fit these cellular couriers with triggers that activate once they’re exposed to heat. By heating tumors in mouse models and in the lab, they demonstrated the ability to control when the drugs are released.

“Temperature-sensitive liposomes have the potential to travel safely around the body while carrying your cancer drug of choice. Once they reach a ‘hotspot’ of warmed-up cancer cells, the pin is effectively pulled and the drugs are released,” said Kostarelos. “This allows us to more effectively transport drugs to tumors, and should reduce collateral damage to healthy cells.”

One step closer to the “holy grail” of cancer treatments

As Kostarelos said in a statement, the liposomes are activated when they are exposed to body temperatures of 42 degrees Celsius (107.6 degrees Fahrenheit). One of the studies showed the effectiveness of temperature-sensitive lipid-peptide hybrids in releasing doxorubicin, while a second study demonstrated the success of chemically stable, heat-activated liposomes.

“Although this work has only been done in the lab so far,” he explained, “there are a number of ways we could potentially heat cancer cells in patients – depending on the tumor type – some of which are already in clinical use.”

Professor Charles Swanton, chair of the 2015 NCRI Cancer Conference, called liposomes “a holy grail of nanomedicine. But finding ways to accurately direct the liposomes towards tumors has been a major challenge in targeted drug delivery.”

The new studies “demonstrate for the first time how they can be built to include a temperature control, which could open up a range of new treatment avenues,” Swanton added. “This is still early work but these liposomes could be an effective way of targeting treatment towards cancer cells while leaving healthy cells unharmed.”


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