Medical information for Melanoma, Merkel cell carcinoma and tumor mutation burden

 

Background:


Melanoma

Also called: malignant melanoma

The most serious type of skin cancer.
Melanoma occurs when the pigment-producing cells that give color to the skin become cancerous.
Symptoms might include a new, unusual growth or a change in an existing mole. Melanomas can occur anywhere on the body.
Treatment may involve surgery, radiation, medications, or in some cases chemotherapy.

Merkel cell carcinoma (MCC)

it is a very rare, highly aggressive, neuroendocrine carcinoma of the skin; 
it has a worse survival probability compared with more common cutaneous malignancies, including metastatic melanoma, and has been termed the “most lethal” skin cancer as patients with metastatic MCC have a historical 5-year overall survival (OS) rate of 18%

What Is Tumor Mutational Burden?

TMB is defined as the frequency of certain mutations within a tumor’s genes. 

To be counted towards TMB, mutations have to alter the protein that is made from a gene.

 Each of these mutations results in a protein that is an antigen and could be recognized by and activate the immune system against the tumor. 

The more antigens produced by a tumor, the greater the chance that one or more antigen will be recognized as foreign by the immune system.

Why might high TMB predict response to immunotherapy?

Highly mutated tumors produce many antigens, which may stimulate T cells to respond to the antigens and mount an anti-tumor response.

Studies have shown that a high TMB in patients with a range of tumor types can predict response to immune checkpoint inhibitors that target the proteins PD-1 or PD-L1.



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