What Is Immunotherapy for Lung Cancer?
Immunotherapy uses medicines to activate the body’s own immune system to recognise and destroy cancer cells. Some cancer cells produce proteins that allow them to hide from immune defenses by switching off the body’s natural response. Immunotherapy drugs block these signals, allowing the immune system to detect and attack the tumour more effectively. Today, this approach is a standard treatment option for many people diagnosed with non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).
How Do Checkpoint Inhibitors Work?
The most common type of immunotherapy in lung cancer is immune checkpoint inhibitors (ICIs). These target the PD-1/PD-L1 pathway: cancer cells produce PD-L1, which binds to PD-1 receptors on T cells and switches off the immune attack. Checkpoint inhibitors block this connection, reactivating T cells to recognise and destroy the cancer.
A second target is CTLA-4, which when blocked increases the number of T cells available to attack cancer cells. Ipilimumab (anti-CTLA-4) is sometimes combined with nivolumab in lung cancer settings.
PD-L1 Testing - Who Is Eligible?
Before immunotherapy is recommended, your tumour is tested for PD-L1 expression - the proportion of cancer cells carrying the protein that suppresses immune responses. The result guides treatment choice:
- High PD-L1 (≥50%) - pembrolizumab monotherapy is approved as first-line treatment
- Intermediate PD-L1 (1-49%) - immunotherapy combined with chemotherapy is typically recommended
- Low/no PD-L1 (<1%) - combined approaches or chemotherapy may be preferred
PD-L1 is not the only factor. Patients with actionable mutations such as EGFR or ALK are treated with targeted therapy first, regardless of PD-L1 level. Full biomarker testing is essential before any treatment decision.
Approved Immunotherapy Drugs for Lung Cancer
For Non-Small Cell Lung Cancer (NSCLC)
- Pembrolizumab (Keytruda) - first-line monotherapy for high PD-L1 NSCLC; combined with chemotherapy for all comers; approved adjuvant and neoadjuvant
- Nivolumab (Opdivo) - neoadjuvant combined with chemotherapy for resectable NSCLC; CheckMate 816 showed 24% pathological complete response rate vs 2% with chemotherapy alone
- Atezolizumab (Tecentriq) - adjuvant after surgery for Stage II-IIIA; used in combination for metastatic NSCLC
- Durvalumab (Imfinzi) - consolidation after chemoradiation for unresectable Stage III (PACIFIC trial); also perioperative
For Small Cell Lung Cancer (SCLC)
- Atezolizumab - approved with carboplatin and etoposide as first-line treatment for extensive-stage SCLC
- Durvalumab - approved with etoposide and platinum chemotherapy for extensive-stage SCLC; also used as consolidation for limited-stage SCLC following chemoradiotherapy
When Is Immunotherapy Used?
Immunotherapy is now used across multiple treatment settings:
- Neoadjuvant (before surgery) - combined with chemotherapy for resectable NSCLC
- Adjuvant (after surgery) - reduces recurrence risk; approved for selected Stage IB-III NSCLC
- Consolidation (after chemoradiation) - durvalumab is standard of care for unresectable Stage III NSCLC
- First-line advanced/metastatic - monotherapy for high PD-L1 NSCLC or combined with chemotherapy broadly
- First-line SCLC - added to chemotherapy for extensive-stage disease
It is given by intravenous infusion every two to four weeks. In adjuvant settings, treatment typically runs for one year; for advanced disease, up to two years or as long as the cancer responds.
Side Effects of Immunotherapy for Lung Cancer
Because immunotherapy stimulates the immune system broadly, it can cause inflammation in almost any organ - these are called immune-related adverse events (irAEs), which differ from chemotherapy side effects and require close monitoring.
Common side effects include fatigue, skin rash or itching, diarrhoea, nausea, and reduced appetite.
Serious immune-related reactions requiring urgent attention include:
- Pneumonitis (lung inflammation) - particularly significant in lung cancer patients; presents as worsening breathlessness
- Hepatitis, colitis, and endocrinopathies (thyroid, adrenal, or pituitary gland inflammation)
- Myocarditis - rare but potentially life-threatening
Immune-related side effects can appear weeks to months into treatment and in some cases up to two years after stopping. Contact your cancer team immediately if new or worsening symptoms develop. Most are managed with corticosteroids, and treatment may need to be paused or permanently stopped.
Conclusion
Immunotherapy has changed how lung cancer is treated by supporting the immune system to recognize and destroy cancer cells more effectively, immunotherapy can offer longer-lasting responses for many patients compared with traditional treatments. However, it is not suitable for everyone, and tests such as PD-L1 and other biomarkers help doctors determine who is most likely to benefit. With proper monitoring for side effects and the right treatment plan, immunotherapy has become an important part of modern lung cancer care.
