Approved indications (US)
Imfinzi (durvalumab) is an IV immunotherapy for adults used in:

• Non‑small cell lung cancer (NSCLC): perioperative treatment of resectable tumors (≥4 cm and/or node‑positive) with chemotherapy then Imfinzi alone; single‑agent consolidation after chemoradiation for unresectable Stage III disease; and in combination with tremelimumab‑actl and platinum‑based chemotherapy for metastatic NSCLC without EGFR or ALK driver alterations.
• Small cell lung cancer (SCLC): single‑agent maintenance after concurrent chemoradiation for limited‑stage SCLC; and in combination with etoposide plus carboplatin or cisplatin as first‑line therapy for extensive‑stage SCLC.
• Gastrointestinal and hepatobiliary cancers: in combination with gemcitabine and cisplatin for locally advanced or metastatic biliary tract cancer; in combination with tremelimumab‑actl for unresectable hepatocellular carcinoma; and with FLOT chemotherapy as neoadjuvant and adjuvant treatment, followed by Imfinzi alone, for resectable gastric or gastroesophageal junction adenocarcinoma.
• Gynecologic and urologic cancers: with carboplatin and paclitaxel followed by Imfinzi monotherapy for primary advanced or recurrent mismatch‑repair‑deficient (dMMR) endometrial cancer; and with gemcitabine and cisplatin as neoadjuvant therapy then Imfinzi alone as adjuvant therapy after cystectomy for muscle‑invasive bladder cancer.

Off‑label uses
Outside clinical trials, off‑label use of Imfinzi is limited; it has been explored in studies for other solid tumors (such as certain head and neck or pancreatic cancers), but evidence is generally early‑phase and less robust than for its approved indications, so most use follows labeled settings or formal research protocols.

Efficacy expectations
In its approved indications, many patients achieve disease control or tumor shrinkage within roughly 6–12 weeks (the first 2–3 scans), with a subset experiencing long‑lasting responses and meaningful improvements in progression‑free and overall survival compared with chemotherapy alone, while others may have minimal or no benefit.

Comparison to similar drugs
Imfinzi’s overall effectiveness is broadly similar to other PD‑1/PD‑L1 checkpoint inhibitors used in comparable settings, but it has specific phase 3 data and regulatory approvals in certain cancers (such as unresectable Stage III NSCLC, SCLC, biliary tract cancer, and perioperative bladder and gastric/GEJ cancers) that often make it a preferred agent in those particular scenarios.

How Imfinzi is given
Imfinzi is administered only by healthcare professionals as an intravenous infusion over about 60 minutes in a clinic or infusion center, typically once every 2, 3, or 4 weeks depending on the cancer type and whether it is combined with chemotherapy or tremelimumab‑actl.

Typical adult dosing patterns

• For NSCLC and SCLC, adults who weigh at least 30 kg usually receive a fixed 1,500 mg dose (with weight‑based dosing for those under 30 kg) every 2, 3, or 4 weeks, often in combination with chemotherapy or tremelimumab for several cycles followed by Imfinzi alone as maintenance or consolidation.
• For biliary tract cancer, unresectable hepatocellular carcinoma, dMMR endometrial cancer, muscle‑invasive bladder cancer, and resectable gastric or gastroesophageal junction cancers, Imfinzi is given at fixed or weight‑based doses every 3 or 4 weeks with specific chemotherapy or tremelimumab, then continued every 4 weeks as a single agent until disease progression, unacceptable toxicity, or a defined maximum number of cycles.

Special dosing instructions
Dose timing or continuation may be modified if patients develop significant immune‑related or other side effects; clinicians may delay doses, withhold treatment, or permanently stop Imfinzi, and premedications (such as antihistamines, antipyretics, or corticosteroids) may be used in those with prior infusion reactions.

Missed doses and overdose
If an infusion appointment is missed, patients should contact their oncology team promptly to reschedule rather than attempting to combine or move doses on their own, and any suspected overdose or extra dose should be managed in a medical setting with observation and supportive care since there is no specific antidote for Imfinzi.

Common side effects
Most people receiving Imfinzi experience some side effects, which vary by cancer type and combination therapy but commonly include:

• Fatigue or weakness, decreased appetite, nausea, vomiting, constipation or diarrhea.
• Cough, shortness of breath, or other respiratory symptoms.
• Rash, itching, hair loss, joint or muscle aches, and changes in blood counts or lab tests (such as liver enzymes, thyroid levels, or electrolytes).

These effects usually begin in the first weeks to months of treatment and are often mild to moderate, but they can sometimes be more severe and lead to treatment delays or stopping therapy.

Serious or rare adverse effects needing urgent care

• Immune‑mediated lung, gut, liver, kidney, or skin problems: new or worsening cough or shortness of breath (possible pneumonitis), severe diarrhea or abdominal pain (colitis), yellowing of skin or eyes or dark urine (hepatitis), markedly reduced urine output (nephritis), or severe rash or blistering skin.
• Endocrine and other organ inflammation: extreme fatigue, dizziness, headache, vision changes, weight changes, feeling unusually cold or hot, excessive thirst or urination, chest pain, palpitations, weakness, numbness, or confusion, which may signal thyroid, adrenal, pituitary, pancreatic, cardiac, neurologic, or other serious immune‑related reactions.

These events are treated by stopping Imfinzi temporarily or permanently and using corticosteroids or other immunosuppressive medicines, so rapid recognition and reporting are critical.

Warnings and precautions

• Pregnancy: Imfinzi can harm an unborn baby; effective contraception is recommended during treatment and for several months after the last dose.
• Breastfeeding: Because it is unknown if Imfinzi passes into breast milk, breastfeeding is not recommended during treatment and for a period after the final infusion.
• Children and older adults: Safety and effectiveness in pediatric patients have not been established; older adults were included in trials and can benefit, but frailty and other illnesses may increase risks and require closer monitoring.
• Kidney or liver disease: No routine dose adjustment is specified, but patients with underlying hepatic or renal impairment may be more vulnerable if immune‑mediated hepatitis or nephritis occurs, so baseline and periodic labs and symptom checks are important.

Overall safety profile
Compared with standard chemotherapy, Imfinzi tends to cause less hair loss, nausea, and low blood counts but carries a distinct risk of sometimes severe or life‑threatening immune‑mediated toxicities that can affect almost any organ, including after therapy has been stopped.

Side‑effect reporting and safety updates
Patients should promptly inform their oncology team about any new or worsening symptoms; side effects can also be reported to the FDA’s MedWatch program, and updated safety information is available through the FDA and the manufacturer’s prescribing information and medication guide.

Drug and supplement interactions

• Imfinzi is a monoclonal antibody broken down by normal protein pathways and does not significantly affect liver drug‑metabolizing enzymes, so classic pharmacokinetic interactions with most medicines are unlikely.
• Chronic high‑dose systemic corticosteroids and other strong immunosuppressive drugs can blunt the immune‑activating effect of Imfinzi and increase infection risk, so they are avoided when possible except when needed to manage immune‑related side effects.
• Patients should tell their oncology team about all prescription and over‑the‑counter drugs, vitamins, herbal remedies, and supplements, since immune‑stimulating or interacting products may complicate management or side‑effect assessment.

Food, alcohol, and vaccines

• Food does not affect Imfinzi because it is given intravenously; alcohol has no direct interaction but should be limited, particularly in people with liver disease or those receiving hepatotoxic chemotherapy.
• Live vaccines are generally avoided during treatment and for some time afterward, while inactivated vaccines (such as influenza or COVID‑19 boosters) may be used with guidance from the oncology team.

Conditions and co‑medications requiring caution

• Pre‑existing autoimmune diseases (for example inflammatory bowel disease, lupus, rheumatoid arthritis), prior organ or allogeneic stem cell transplantation, uncontrolled infections, significant cardiac or lung disease, or chronic viral hepatitis require individualized risk–benefit discussion because immune activation may worsen these conditions.
• Patients who have had or may need allogeneic stem cell transplantation or solid organ transplantation may be at higher risk of severe graft‑versus‑host disease, rejection, or other immune complications when exposed to checkpoint inhibitors like Imfinzi.

Monitoring
Before and during treatment, clinicians typically monitor complete blood counts; liver and kidney function; thyroid and other endocrine labs; blood glucose and electrolytes; and perform regular physical exams and imaging studies to track tumor response and detect early signs of immune‑related toxicity, adjusting treatment as needed.

Q: Is Imfinzi the same as chemotherapy?
A: No, Imfinzi is an immunotherapy (a PD‑L1 blocking antibody) that helps your immune system recognize and attack cancer cells; it is sometimes given with chemotherapy but works differently and has a distinct side‑effect profile.

Q: How long will I stay on Imfinzi?
A: The duration depends on your cancer type and response, but many regimens continue Imfinzi until the cancer clearly progresses, side effects become unacceptable, or a set maximum number of cycles (often around 12–24 months or a defined adjuvant course) is completed.

Q: When might I notice if Imfinzi is working?
A: Doctors usually check scans every few months, and benefits—such as tumor shrinkage or stable disease—are often seen within the first 2–3 imaging visits, although some people may respond later or not at all.

Q: What are the most serious risks with Imfinzi?
A: The most serious risks are immune‑mediated reactions in organs like the lungs, intestines, liver, kidneys, endocrine glands, heart, or nervous system, which can be life‑threatening but often improve if recognized early, Imfinzi is held, and prompt steroid treatment is started.

Q: Can I receive Imfinzi if I have an autoimmune disease or have had a transplant?
A: It may still be considered in some cases, but the risks of flaring an autoimmune condition or causing graft‑versus‑host disease or organ rejection are higher, so the decision requires careful discussion with your oncology team and, when relevant, your rheumatologist or transplant specialists.