By Nancy Cui, MD, PhD, Oncology & Hematology Clinic
Cancer immunotherapy has recently emerged as a transforming advance in cancer treatment, especially immune checkpoint inhibitor therapy. Positively impacting treatment for many different types of cancer, its applications in the research and clinical settings are rapidly progressing as well.
Because cancer immunotherapy is a complex process, this brief overview is meant to help our patients and families understand and actively participate in immunotherapy treatment and management, with a special focus on checkpoint inhibitor immunotherapy which is now widely used.
What’s the function of the immune system?
Our immune system has three main functions:
- The surveillance function knows the difference between our “self” normal cells from “non-self” cells, like virus or cancer cells.
- The cytotoxic/killing function destroys non-self and cancer cells.
- The memory function recognizes and destroys repeated invaders or cancer cells.
What are the components of immune system?
It includes mainly B cells and T cells, with other cells also involved.
- B cells produce antibodies to attach to invaders to allow them to be destroyed.
- T cells’ function is the most complexed and critical. It carries out the immune system’s three functions (mentioned above) through multiple signals/molecules. Some signals involved are called “immune checkpoints” molecules, such as CTLA-4 and PD-1.
How do cancer cells escape the immune system?
Cancer cells can make themselves “invisible,” secrete chemicals to create a “shield” or a “brake,” or produce the immune checkpoint molecule PD-L1 on their surface to “block” the T cells’ killer function.
What are the types of immunotherapies commonly used in cancer treatment?
- Antibody therapy targets cancer cells bearing specific markers.
- CTLA-1 checkpoint inhibitor therapy (ipilimumab) releases the “brake” of immune killer cells.
- PD or PD-L1 checkpoint inhibitors (pembrolizumab, nivolumab for example) remove the “block” between immune cells and cancer cells to restore immune system function to recognize and destroy cancer cells.
- CAR-T cell therapy extracts patient’s own T cells and modifies them in the lab to make them target those immune “escaped” tumor cells. This is mainly used to treat blood cancers and is not used at Valley, but is available at Seattle Cancer Care Alliance.
What types of cancers are treated by checkpoint inhibitor immunotherapy?
Checkpoint inhibitor immunotherapy can be used to treat cancer of the kidney, skin (melanoma), lung, triple negative breast, head, neck, esophagus, stomach, cervical, bladder and biomarker MSI-H or TMB-H cancers. While mainly used to treat late stage cancers, some cancers require certain biomarkers and other cancers need to be treated in combination with chemotherapy.
How is checkpoint inhibitor immunotherapy administered?
Checkpoint inhibitor immunotherapy is given through IV infusion. The schedule can be varied and ranges every 2 – 4 weeks.
What are the side effects of checkpoint inhibitor immunotherapy? Can the side effects be treated?
- This type of therapy is usually well tolerated with a side effects rate in 10 – 20% range. It is related to general immunologic enhancement and can involve any organs or tissues of body.
- Common symptoms include skin rash, diarrhea, pneumonitis, thyroid dysfunction, etc.
- Most side effects can be managed well with a steroid if treated early. If treated late, it can be life threatening. It’s important to monitor any changes after immunotherapy and report side effects to the physician EARLY.
Once a cancer is diagnosed, oncologists will assess and send out appropriate biomarker studies. Indications for immunotherapy will be discussed. If checkpoint inhibitor immunotherapy treatment is started, the patient’s response will be closely monitored, as will side effects.