For combating the most aggressive type of skin cancer, a new class of immunotherapy has shown encouraging results.

The study examines whether a new antibody can target and cure melanomas. It was published on April 25 in Nature Communications by researchers from Guy's and St Thomas' NHS Foundation Trust and King's College London.

The outcomes demonstrate that the antibody stimulates the immune system's response to fight cancer and inhibits the growth of melanoma in experimental model. The most harmful form of skin cancer, malignant melanoma, has a poor five-year survival rate for half of patients.

Although immunotherapies (drugs that activate the body's natural defence system to target cancer) have made significant advancements, many patients' cancers still do not respond. Patients with melanoma who do not respond to current therapy may benefit from this medication.

Many existing immunotherapies used in cancer treatment belong to the antibody type called IgG. However, researchers at King's College London and Guy's and St Thomas' have developed an IgE antibody which can utilise the patient's own immune system to attack cancer in a different way.

Researchers developed an IgE antibody specific for a marker on the surface of human melanoma cells, called chondroitin sulfate proteoglycan 4 (CSPG4) found on up to 70% of melanomas. Immunotherapies currently available draw broadly upon the immune system's defences, however this new antibody was designed to target immune responses specifically towards melanoma cells.

The researchers showed that CSPG4 IgE could attach to and activate immune cells found in melanoma patient blood to kill human melanoma cancer cells. CSPG4 IgE treatment slowed cancer growth in experimental model implanted with human immune cells, including cells from patients with melanoma.

An allergy test conducted with patient blood found that CSPG4 IgE did not activate white blood cells called basophils, indicating that the therapy may be safe to take.

Dr Heather Bax, Postdoctoral Research Fellow from St. John's Institute of Dermatology, King's College London, said: "We have shown that an immune response can be triggered by IgE immunotherapy for melanoma and that this applies to human melanomas and to melanoma patient immune responses."

"Our findings replicate existing observations for MOv18 IgE, the firstanti-cancer IgE, which targets ovarian cancer, and supports development of IgE therapies for other solid tumors".

Professor Sophia Karagiannis, from St. John's Institute of Dermatology, King's College London, said: "Four in ten people with advanced melanoma do not respond to available treatments."

"Our findings show that the human immune system reacts differently in the presence of drugs based on IgE antibodies and points to the potential of applying IgE to mount an effective response against melanoma. This opens up the possibility of this new class of drugs to benefit different patient groups and a new frontier in the battle against cancer."

Professor James Spicer, from King's College London and a Consultant at Guy's and St Thomas' NHS Foundation Trust, said: "We have recently completed the first ever trial testing an IgE therapy for cancer (MOv18 IgE), and are excited about the prospect of a whole new class of antibody drugs in oncology."

"The collaboration between the King's College London and Guy's and St Thomas' research groups is close and ever more productive."