Teachable moment in classrooms:

  1. integumentary system chapter – location and function of melanocytes in skin
  2. lymphatic and immune system chapter – the role of T lymphocytes (T cells) in the immune defense reaction
  3. lymphatic and immune system chapter – mechanism of cell killing by cytotoxic T cells

The news item:  Recently this report appeared online:

Patient is first treated with drug newly OK’d for melanoma

A Stanford Medicine melanoma patient is first in the nation to receive a cell-based therapy the FDA has approved for treating solid tumors.

The article informs us that a new therapy called “lificel” is being employed to treat patients with metastasized melanoma. The therapy includes removing a portion of the melanoma, extracting T cells from the tumor, stimulating the T cells to multiply into the millions, and infusing the new T cells into the patient.

So, Why Do I Care??  There are about 1.4 million people in the US alone living with melanoma, and the yearly new diagnosed cases are over 100,000. There are about 8,000 deaths from melanoma yearly. The metastasized stage of melanoma has a 5-year survival rate of about 20%. It is important to evaluate new therapies, because we want to increase the survival rate.

Plain English, Please!!!   First, let’s talk about what metastasized melanoma is. Normally melanocytes reside in the epidermis layer of the skin where they produce the dark substance called melanin which protects the cells from UV light. When melanocytes start to divide uncontrollably, a cancer called melanoma forms. Melanomas have the tendency to release clumps of cancer cells, and those clumps spread through lymphatic vessels and grow into new cancer lump. Those new cancer lumps are called metastasis. Traditional chemotherapy drugs have been unable to kill off metastasized melanomas.

Second, let’s talk about how our immune system fights melanoma. Whenever cancer cells form, they produce modified proteins and sometimes new proteins, that trigger an immune reaction. Those cancer antigens cause the activation, proliferation and differentiation of T lymphocyte (T cells) into cytotoxic T cells attracted to the cancer cells. Once the cancer-specific cytotoxic T cells are released from the lymph nodes, they move into cancer lumps, and start destroying the cancer cells.  Picture a melanoma lump as a building. Each cytotoxic T cell attacks a specific antigen, so in this building some of the T cells attack the window frames, some attack the flooring, some attach the light fixtures. In theory, the entire lump can be degraded this way. The melanoma may still survive the immune attack, either because the cancer cells may hide themselves behind a molecular shield the T cells don’t attack, or, because the number of cytotoxic T cells may be too low to cause lasting damage to the lump.

Third, let’s talk about how the “lificel” therapy works. At the beginning of this therapy a part of the melanoma lump is removed surgically, and the multiple kind of T cells are collected from the melanoma tissue. The T cells are then placed in cell culture, stimulated to divide, and the millions of new T cells are infused back into the patient. The infused T cells have diverse targets, so millions of T cells that attack different portions of the “building” of melanoma lump, and those large number of T cells can now overwhelm and degrade the melanoma lump. This way melanoma lumps that resisted chemotherapy treatments can be eliminated.