Candidate found to inhibit the growth of malignant melanoma

Malignant melanoma is a relatively aggressive type of skin cancer. When detected early, it is usually treatable only by surgical resection, but metastases develop, often spreading to distant areas.

Currently, tumor thickness and presence of ulceration are some of the prognostic factors known to be used as indicators of melanoma. Therefore, the discovery of markers to more accurately assess the malignancy potential of melanoma may be necessary to develop appropriate treatment.

‘Cross talk’ between cancer cells and surrounding stromal cells is believed to regulate cancer development through various mechanisms. Cancer-associated fibroblasts (CAFs) – a key factor in the tumor microenvironment – ​​in particular have been implicated in cancer cell development. It has also been reported that exosomes, a type of small vesicles, produced by CAFs play an important role in cancer development.

A research group led by Naho Fujii and Hisashi Motomura of the Osaka Metropolitan University Graduate School of Medicine in Japan investigated the effect of CAF-derived exosomes on malignant melanoma cell growth.

The group found that the transmembrane proteins CD9 and CD63 were predominantly present in CAF-derived exosomes, and among exosomes, those that were CD9 positive inhibited growth of malignant melanoma cells.

“As a plastic surgeon, I usually provide surgical treatment for skin cancer, but I have long wanted to learn other treatment methods,” said Fujii.

“This study shows that CD9-positive exosomes inhibit the growth of malignant melanoma, so CD9-positive exosomes can be a useful marker for evaluating the level of melanoma malignancy. We hope further research will lead to the development of new treatments in that area.”

Last December, ImaginAb launched a clinical trial to look into early detection of malignant melanoma.