Yale scientists are developing an injection that could kill skin cancer cells.
The shot contains a chemotherapy drug carried by nanoparticles that bind to tumours.
When tested in the laboratory, the nanoparticles attached to malignant cells well, slowly releasing the chemotherapy drug over more than 10 days.
Finding alternative skin cancer treatments is considered a “holy grail” in the field, according to the Yale team.
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By targeting the tumour site specifically, aggressive chemotherapy drugs can be administered that do not affect the entire body, leading to side effects.
Skin cancer patients often also have to go under the knife, raising the risk of infections.
Melanoma, the most life-threatening form of skin cancer, affects around 16,000 new people every year in the UK, of which more than four in five (86%) cases are preventable via good sun safety.
More than 151,000 new people develop non-melanoma skin cancer every year, with surgery being the most common treatment.
“That’s always been a holy grail in dermatology, to find a simpler way to treat skin cancers such as basal cell carcinoma and squamous cell carcinoma,” said study author Dr Michael Girardi.
Basal cell carcinoma starts in the cells lining the bottom of the epidermis, the outermost layer of skin.
Squamous cell carcinoma originates in the cells lining the top of the epidermis.
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Testing the injection in the laboratory, around 50% of the chemotherapy drug camptothecin was retained in the tumours 10 days later.
The shot also “significantly reduced tumour burden”, with around one in five (20%) of the malignant cells “showing histologic cure”.
Camptothecin was undetectable when administered alone, without the binding nanoparticles.
“When you inject our nanoparticles into a tumour, it turns out they’re retained within that tumour very well,” said co-author Professor Mark Saltzman.
“They accumulate and bind to the tumour matrix, so one single injection lasts for a very long time; the particles stay there and slowly release the compounds.
“You need that to get rid of the lesion.”
Treating larger “more fully established” tumours with a combination of the shot and immune-stimulating drugs led to even better outcomes.
“I call the phenomenon ‘kill and thrill,’” said Dr Girardi.
“You don't want to just kill the cells and leave them there, you want to stimulate the immune system to clean up the mess and also react against cells that might not have been killed directly.
“So it’s a two-pronged attack on the cancer.”
In the study, published in the journal PNAS, the scientists delivered just one injection to the tumours.
“That’s how we’d like it to work clinically,” said Professor Saltzman.
“You go to a dermatologist, they see a lesion and inject into it, and it’s gone and you don't have to come back.”
The scientists concluded that with or without “immunostimulation”, the injection “represents a viable, nonsurgical alternative for treating cutaneous malignancy”.
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