Atezolizumab

Atezolizumab is a recombinant humanized monoclonal antibody belonging to the immune checkpoint inhibitor class of anticancer medicines. It targets programmed death-ligand 1, or PD-L1, a protein expressed by many cancer cells and immune cells within the tumor environment. By binding to PD-L1, atezolizumab prevents its interaction with PD-1 and B7.1 receptors and helps restore immune-cell activity against cancer cells. Atezolizumab is administered as an intravenous infusion, while a combination formulation containing atezolizumab and hyaluronidase is available for subcutaneous administration in appropriate adult indications. Depending on the cancer and regulatory indication, it may be used alone or in combination with chemotherapy, targeted therapy or other immunotherapy-related treatment. Current approved uses include selected forms of non-small cell lung cancer, extensive-stage small cell lung cancer, hepatocellular carcinoma, melanoma, alveolar soft part sarcoma and, in the United States, a molecular-residual-disease-selected adjuvant setting for muscle-invasive bladder cancer. Treatment schedules vary by indication and formulation. Because immune checkpoint blockade can activate the immune system against cancer cells as well as normal tissues, careful monitoring for immune-mediated inflammation and organ dysfunction is an important part of treatment.

Atezolizumab was developed as a humanized monoclonal antibody designed to inhibit the PD-L1 immune checkpoint pathway. The U.S. Food and Drug Administration granted its initial approval on 18 May 2016 for patients with locally advanced or metastatic urothelial carcinoma in specified treatment settings. Subsequent FDA approvals expanded its use to non-small cell lung cancer, extensive-stage small cell lung cancer, hepatocellular carcinoma, melanoma and alveolar soft part sarcoma. In October 2025, FDA approved atezolizumab in combination with lurbinectedin for maintenance treatment of adults with extensive-stage small cell lung cancer whose disease had not progressed after first-line induction with atezolizumab plus carboplatin and etoposide. In May 2026, FDA approved atezolizumab and the subcutaneous atezolizumab and hyaluronidase formulation as adjuvant treatment for selected adults with muscle-invasive bladder cancer after cystectomy who have detectable circulating tumor DNA molecular residual disease using an FDA-authorized test. The European Union granted marketing authorisation for Tecentriq on 20 September 2017, with subsequent variations expanding and modifying its approved indications. Indian regulatory records document atezolizumab as an approved and regulated recombinant biological product, including 1200 mg/20 mL injection presentations. Major clinical development programmes include IMpower130, IMpower150, IMpower133, IMpower110, IMpower010, IMbrave150, IMpower132, IMpassion130 and IMpower311.

Atezolizumab is used for selected advanced, metastatic or adjuvant cancer settings, with the exact indication depending on the regulatory jurisdiction, disease characteristics, biomarker status and previous treatment. In the United States, current indications include adjuvant treatment of adults with Stage II to IIIA non-small cell lung cancer following resection and platinum-based chemotherapy when tumor PD-L1 expression meets the specified threshold; first-line treatment of selected metastatic non-small cell lung cancer; combination treatment for metastatic non-squamous non-small cell lung cancer; treatment of metastatic non-small cell lung cancer following platinum-containing chemotherapy; first-line extensive-stage small cell lung cancer with carboplatin and etoposide; maintenance treatment of selected extensive-stage small cell lung cancer in combination with lurbinectedin; unresectable or metastatic hepatocellular carcinoma with bevacizumab in patients without prior systemic therapy; BRAF V600 mutation-positive unresectable or metastatic melanoma with cobimetinib and vemurafenib; unresectable or metastatic alveolar soft part sarcoma in adults and pediatric patients aged 2 years and older; and adjuvant treatment of selected muscle-invasive bladder cancer with molecular residual disease after cystectomy. Some historical urothelial carcinoma indications have been withdrawn or modified in certain jurisdictions. European indications differ and include selected urothelial carcinoma, non-small cell lung cancer, extensive-stage small cell lung cancer, triple-negative breast cancer and hepatocellular carcinoma. Treatment should therefore be based on the approved indication applicable to the patient's jurisdiction and clinical situation.

Atezolizumab intravenous therapy is administered by infusion, with the first infusion generally given over approximately 60 minutes and subsequent infusions potentially shortened if the initial administration is well tolerated. For many adult indications, approved intravenous dosing includes 840 mg every 2 weeks, 1200 mg every 3 weeks or 1680 mg every 4 weeks, depending on the cancer type and treatment regimen. Adjuvant non-small cell lung cancer and selected muscle-invasive bladder cancer treatment may continue for up to 1 year when the applicable eligibility criteria are met. In extensive-stage small cell lung cancer, atezolizumab may be continued until disease progression or unacceptable toxicity according to the approved regimen. When used with chemotherapy or bevacizumab, the sequence of administration should follow the applicable prescribing information, with atezolizumab generally administered before the other same-day intravenous medicines. The subcutaneous atezolizumab and hyaluronidase formulation is administered as a fixed injection every 3 weeks in approved adult indications. Pediatric dosing for alveolar soft part sarcoma is weight-based. Treatment duration and dose interruptions depend on disease status, toxicity and clinical response.

Common side effects of atezolizumab include fatigue, weakness, decreased appetite, nausea, cough, shortness of breath, fever, diarrhea, constipation, rash, itching, musculoskeletal pain and infusion-related reactions. Laboratory abnormalities such as changes in liver enzymes, thyroid function, blood counts or kidney function may also occur. When atezolizumab is administered with chemotherapy, bevacizumab, targeted therapy or other anticancer medicines, some adverse effects may be caused by the combination rather than atezolizumab alone. The frequency and severity of side effects vary according to the cancer type, treatment regimen and individual patient factors. Many mild or moderate reactions can be managed with supportive care and appropriate monitoring, while persistent or clinically significant immune-related symptoms may require treatment interruption and specific medical management.

Atezolizumab can cause serious or potentially life-threatening immune-mediated adverse reactions affecting almost any organ system. Important toxicities include immune-mediated pneumonitis, colitis, hepatitis, nephritis and renal dysfunction, thyroid disorders, hypophysitis, adrenal insufficiency, type 1 diabetes mellitus, severe skin reactions, encephalitis, meningitis, myelitis, myocarditis and other neurologic or cardiac inflammatory disorders. Severe infusion-related reactions can also occur. Immune-mediated adverse reactions may develop during treatment or after treatment has been discontinued. Patients should be monitored for new respiratory symptoms, persistent diarrhea, abdominal pain, jaundice, changes in urine output, endocrine symptoms, neurological changes or other unexplained systemic symptoms. Atezolizumab can also cause complications associated with solid-organ transplantation, including transplant rejection. Treatment interruption, corticosteroid therapy or permanent discontinuation may be required depending on the type and severity of immune-mediated toxicity. Clinically significant liver enzyme, creatinine and thyroid-function abnormalities should be evaluated promptly.

Before treatment, healthcare professionals should review the patient's history of autoimmune disease, organ transplantation, interstitial lung disease or pneumonitis, previous immune-related toxicity and other relevant medical conditions. Baseline and periodic monitoring generally includes liver enzymes, serum creatinine and thyroid function, with additional laboratory or clinical assessments based on the patient's treatment regimen. Patients should be assessed for symptoms of infection and other conditions that may complicate immunotherapy. Atezolizumab does not undergo conventional CYP-mediated metabolism and therefore does not have the typical pharmacokinetic interaction profile associated with many small-molecule medicines. However, concomitant immunosuppressive treatment may affect immune activity and should be considered clinically, particularly when corticosteroids or other immunosuppressants are being used to manage immune-mediated adverse reactions. Pregnancy should be avoided because immune checkpoint inhibition may cause fetal harm. Patients should discuss pregnancy, breastfeeding, vaccination and previous or planned immunosuppressive treatment with their healthcare professional. Combination regimens also require monitoring for the adverse effects and interactions associated with the accompanying medicines.

Prescribers should confirm the exact cancer indication, biomarker requirements, treatment line, combination regimen and applicable dosing schedule before initiating atezolizumab. Baseline evaluation should include liver function, renal function and thyroid function, together with assessment of pulmonary, gastrointestinal, endocrine, neurological and cardiovascular history when clinically appropriate. Patients should be educated that immune-mediated adverse reactions can occur even when treatment initially appears well tolerated and should report new or persistent symptoms promptly. Pharmacists should verify the formulation, dose, infusion or subcutaneous administration requirements, treatment interval and any combination medicines before dispensing or preparing therapy. When atezolizumab is combined with bevacizumab or chemotherapy, laboratory and clinical monitoring should also address toxicities associated with those medicines. For patients receiving subcutaneous atezolizumab and hyaluronidase, correct product selection and administration technique are important. Treatment decisions following suspected immune-mediated toxicity should be coordinated with the oncology team, with corticosteroid or other immunosuppressive management used when clinically indicated.