Tislelizumab

Tislelizumab is a humanised monoclonal antibody and an immune checkpoint inhibitor used in the treatment of certain cancers. It belongs to the programmed cell death protein 1 (PD-1) inhibitor class. PD-1 is a receptor found on immune cells that can limit their activity when it interacts with its ligands, PD-L1 and PD-L2. Some cancer cells use this pathway to reduce the immune system's ability to recognise and attack them. Tislelizumab blocks the interaction between PD-1 and these ligands, helping restore antitumour immune activity. It has been engineered to reduce binding to certain Fc-gamma receptors, a feature intended to limit unwanted effects on immune cells. The medicine is administered by intravenous infusion under the supervision of a qualified oncology team. Depending on the cancer type, tumour characteristics, treatment setting and applicable regulatory approval, it may be used alone or in combination with chemotherapy or other anticancer medicines. Treatment selection can require assessment of biomarkers such as PD-L1 expression and, in some settings, other tumour-specific markers. Tislelizumab is clinically important because it provides an immunotherapy option for selected patients with advanced or earlier-stage cancers. Its benefits must be balanced against potentially serious immune-mediated reactions, making patient selection, counselling and ongoing monitoring essential.

Tislelizumab was developed as an antibody targeting PD-1 and was initially studied under the development code BGB-A317. It was first approved in China in 2019 and subsequently received approvals in other regions for selected malignancies. The US Food and Drug Administration (FDA) granted its first US approval in 2024 for certain adults with unresectable or metastatic oesophageal squamous cell carcinoma and gastric or gastro-oesophageal junction adenocarcinoma, subject to the relevant indication-specific criteria. The European Medicines Agency (EMA) authorised Tevimbra in 2023, with subsequent indication expansions for selected cancers, including certain forms of non-small-cell lung cancer and oesophageal cancer. Approval conditions differ between jurisdictions and may change as new clinical evidence is assessed. Clinical development has included studies evaluating tislelizumab as monotherapy and in combination with chemotherapy across oesophageal, gastric and lung cancers. Its use should follow the current prescribing information applicable to the patient's country and specific cancer indication.

Tislelizumab is used for selected cancers according to the applicable regulatory approval, tumour characteristics and treatment setting. Indications include unresectable or metastatic oesophageal squamous cell carcinoma, certain gastric and gastro-oesophageal junction adenocarcinomas, and specific forms of non-small-cell lung cancer. In eligible patients, it may be prescribed alone after previous systemic treatment or combined with chemotherapy as first-line treatment. Some regimens are restricted by HER2 status, PD-L1 expression, tumour histology, previous treatment or other molecular findings. In certain jurisdictions, tislelizumab is also authorised for additional cancer indications or treatment settings. The approved uses are not identical across countries, so the current local prescribing information should be checked before treatment. It is not appropriate for every patient with these cancers, and the oncology team should consider the expected benefits, alternative therapies, overall health and potential immune-related risks.

Tislelizumab is administered by intravenous infusion in a healthcare setting. The recommended dose and interval depend on the indication, treatment regimen and applicable product label. Commonly authorised schedules include 200 mg every three weeks, while some current US-approved regimens also permit 150 mg every two weeks, 300 mg every four weeks or 400 mg every six weeks in specified settings. Combination treatment requires separate consideration of the dosing schedules and precautions for the accompanying medicines. Treatment is generally continued until disease progression, unacceptable toxicity or another indication-specific stopping point. Depending on the adverse reaction, treatment may need to be withheld or permanently discontinued. The infusion should be prepared and administered by trained healthcare professionals according to the product instructions. Dose selection and any treatment modification must be determined by the treating oncologist rather than adjusted by the patient.

Common or clinically relevant side effects may include fatigue, nausea, reduced appetite, diarrhoea, constipation, rash, itching, fever, cough and changes in thyroid function. When tislelizumab is combined with chemotherapy, additional effects such as anaemia, reduced blood-cell counts, vomiting, hair loss or peripheral nerve symptoms may occur, depending on the chemotherapy regimen. The frequency and severity of adverse effects vary with the treatment combination, cancer type and individual patient. Some symptoms can be managed with supportive treatment and monitoring, but patients should report new, persistent or worsening symptoms promptly. Symptoms should not automatically be attributed to routine treatment effects because some may indicate a serious immune-mediated reaction.

Tislelizumab can cause serious or potentially fatal immune-mediated adverse reactions because it increases immune activity. These may affect the lungs, intestines, liver, kidneys, endocrine glands, skin, heart, nervous system or other organs. Examples include pneumonitis, colitis, hepatitis, nephritis, thyroid dysfunction, adrenal insufficiency, hypophysitis, myocarditis and severe skin reactions. Infusion-related reactions can also occur. Rare but serious complications, including haemophagocytic lymphohistiocytosis, have been reported with tislelizumab. Complications may arise during treatment or after the final dose. Patients receiving allogeneic haematopoietic stem cell transplantation before or after PD-1 inhibitor treatment may face additional risks. Suspected serious immune-mediated toxicity requires prompt assessment and appropriate management, which may include withholding treatment, corticosteroids or other immunosuppressive therapy. Permanent discontinuation may be necessary for certain severe or recurrent reactions. The medicine may also cause fetal harm, so pregnancy prevention and counselling are important.

Before starting tislelizumab, clinicians should assess the cancer diagnosis, treatment history, relevant tumour biomarkers and baseline organ function. A history of autoimmune disease, interstitial lung disease, organ transplantation or previous severe immune-related toxicity requires particular consideration. Baseline and ongoing assessments commonly include blood counts, liver and kidney function, thyroid function and glucose, with additional tests guided by symptoms and clinical circumstances. Patients should inform their healthcare team about all prescription medicines, non-prescription products and supplements they use. Classic pharmacokinetic interactions are generally less prominent with monoclonal antibodies than with many small-molecule medicines, but concomitant immunosuppressants and other anticancer treatments can affect clinical management. Live vaccines should generally be avoided during treatment unless the treating specialist advises otherwise under the applicable guidance. Pregnancy and breastfeeding require specific counselling because of potential fetal harm and limited safety information.

Confirm the precise approved indication and required biomarker results before initiating therapy, and verify the dosing schedule against the current local product information. Document the patient's baseline symptoms, autoimmune history, organ function and concomitant medicines. Explain that immune-mediated reactions can resemble common infections or ordinary treatment effects and may occur even after treatment has ended. Provide clear instructions for promptly reporting breathlessness, persistent diarrhoea, jaundice, severe abdominal pain, marked weakness, unusual headaches, visual changes or other new symptoms. Establish a monitoring plan for blood counts, liver and kidney function, thyroid status and other organ-specific tests as clinically indicated. Pharmacists and infusion staff should verify the prescribed regimen, preparation requirements, infusion procedures and any concurrent chemotherapy instructions. Suspected immune-mediated toxicity should trigger timely clinical assessment rather than unsupervised symptom treatment. Treatment interruptions, corticosteroid use and decisions about restarting or permanently discontinuing therapy should follow the severity of the reaction and specialist guidance.