What is Immunotherapy?

Immunotherapy is an important treatment option for both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). It works by stimulating the body’s immune system to recognise and destroy cancer cells. Normally, the immune system can detect and eliminate abnormal cells, but cancer cells often evade detection by mimicking healthy cells or using “checkpoints” to suppress immune responses.

Checkpoint inhibitors are the most widely used form of immunotherapy in lung cancer. These drugs block proteins such as PD-1 or PD-L1, which cancer cells use to hide from immune cells. By inhibiting these checkpoints, T cells—a type of white blood cell—can better identify and attack cancer cells. This approach has led to improved outcomes for many patients.

In Australia, approved checkpoint inhibitors for lung cancer include pembrolizumab, nivolumab, durvalumab, and atezolizumab. At diagnosis, a biopsy is used to assess PD-L1 expression and identify genetic mutations. If PD-L1 is expressed in more than 50% of tumour cells, immunotherapy may be used as a standalone treatment. If PD-L1 levels are lower or absent, immunotherapy is often combined with chemotherapy to enhance effectiveness.

Immunotherapy is typically administered via intravenous infusion every 2 to 4 weeks in cycles, allowing the body time to recover between treatments. It is usually given in outpatient oncology clinics and may be used before or after surgery, depending on the individual case.

Treatment response varies widely. Some patients experience significant tumour shrinkage, others maintain stable disease, and some may not respond at all. Regular monitoring through imaging and blood tests helps assess how well the treatment is working.

If immunotherapy proves ineffective, other options such as chemotherapy, targeted therapy, radiation, or participation in clinical trials may be considered. Immunotherapy may not be suitable for everyone, and treatment decisions should be guided by individual health factors and test results.