The immune system helps the body fight infections and other diseases by detecting and destroying abnormal cells that have developed into cancer. Unlike traditional chemotherapy, which directly kills cancer cells, immunotherapy aims to “awaken and reactivate” the patient’s own immune system (such as T cells), enabling it to recognise and actively attack hidden cancer cells again.

Under normal circumstances, the immune system has the ability to detect and eliminate abnormal cells. However, cancer cells possess a special mechanism known as “immune evasion.” They can express specific proteins on their surface (such as PD‑L1), which bind to receptors on immune T cells and block immune responses, thereby avoiding detection by the immune system.

Prerequisites for Immunotherapy: PD‑L1 Testing and Biomarkers

Immunotherapy is not necessarily suitable for all patients. Oncologists will perform biopsy analysis to evaluate tumour PD‑L1 expression levels or microsatellite instability (MSI‑H). These biomarkers help predict how well a patient may respond to immunotherapy and guide the most appropriate treatment plan.

Immunotherapy can be administered through intravenous infusion or subcutaneous injection. Common treatment types include:

• Immune Checkpoint Inhibitors: The most widely used class of drugs (e.g. PD‑1 / PD‑L1 inhibitors). They block cancer cells from suppressing T cells, allowing the immune system to recognise and kill cancer cells again.
• Monoclonal Antibodies: Artificially produced immune proteins that attach to specific antigens on cancer cell surfaces, marking the cancer cells and guiding the immune system to target them precisely.
• Chimeric Antigen Receptor T‑Cell Therapy (CAR‑T): A highly personalised advanced therapy. T cells are engineered in a laboratory to express specific receptors that bind to proteins on cancer cells, enabling them to recognise cancer cells. These modified cells are expanded and then reinfused into the patient.
• Cancer Vaccines: Unlike preventive vaccines, therapeutic cancer vaccines aim to stimulate the immune system to help prevent cancer formation or fight existing cancer cells.

As immunotherapy activates the immune system extensively, careful safety evaluation is required before starting treatment:

• Screening for autoimmune diseases:
  If you have conditions such as rheumatoid arthritis, lupus or Crohn’s disease, activating the immune system may worsen these conditions. You should inform your doctor of all past medical history.
• Baseline organ function assessment:
  Comprehensive blood tests, including liver, kidney and thyroid function, will be conducted before treatment as baseline data for monitoring side effects later.

The side effects of immunotherapy differ significantly from traditional chemotherapy. The main risks arise when the immune system becomes overactivated and mistakenly attacks normal organs and tissues, known as immune‑related adverse events (irAEs).

Part 1: Common and Generally Manageable Initial Reactions

During immunotherapy, patients most often experience mild to moderate systemic or local reactions, which are usually signs that the immune system is being activated:

• Fatigue and flu‑like symptoms: The most common reactions, possibly accompanied by mild fever, chills or muscle aches.
• Mild skin reactions: Slight redness around injection sites, rashes or itching.
• Endocrine changes: Such as hyperthyroidism or hypothyroidism, which may initially present as fatigue or slight weight changes.

Part 2: High‑Risk Symptoms and Medical Intervention

Serious immunotherapy‑related side effects should not be managed without medical assessment. If any of the following high‑risk symptoms occur at home, do not treat them as a common cold or gastrointestinal illness—seek medical attention immediately:

• Suspected lung inflammation: New or persistent cough, shortness of breath or chest pain
• Suspected intestinal inflammation: Significant increase in bowel movements (such as three or more per day), watery diarrhoea, blood in stool or severe abdominal pain
• Suspected liver inflammation: Yellowing of skin or eyes, dark urine, persistent pain in the right abdomen

In such cases, the medical team will closely monitor and manage adverse reactions. Before each treatment cycle, detailed blood tests (including liver, kidney and thyroid function) will be conducted according to clinical needs to detect signs of organ inflammation.

If moderate to severe immune‑related inflammation is confirmed, there will be possibilities that doctors may temporarily stop treatment and may prescribe steroids or immunosuppressive medications to control the condition.

The OncoCare medical team will provide clear post‑treatment guidance to ensure patients can access timely support when symptoms arise.

Successful immunotherapy requires precise dosing and close monitoring of side effects.
OncoCare’s experienced oncology clinical team strives to closely monitor treatment progress and side effects, ensuring patients can complete treatment safely in a private and comfortable environment.