More common side effects that don't require medical attention unless they are bothersome:

• Pain or tenderness where the needle is placed
• Diarrhea
• Reduced immune system, meaning you are at higher risk of getting an infection.
• Constipation
• Loss of appetite / weight loss

Tarlatamab is an antineoplastic medication. It is a type of protein designed to help your own body’s immune system target cancer cells to stop them from growing.

Check with your healthcare team or get emergency help immediately if you have:

• More than one of these symptoms: fever, chills, dizziness, shortness of breath, nausea, vomiting, fast heartbeat, unusual tiredness, headache, or muscle/joint pain
• Nerve problems such as tremors or muscle spasms, having trouble walking, writing, or speaking, headache, feeling anxious (nervous) or confused, having trouble thinking, hearing loss, or changes in eyesight such as double vision.
• Signs of an allergic reaction soon after treatment such as dizziness, fast heartbeat, face swelling, or breathing problems.
• An infection, which may cause fever (over 38°C or 100°F by an oral thermometer), shaking chills; severe sore throat, productive cough (coughing up thick or green sputum); cloudy or foul smelling urine; painful, tender, or swollen red skin wounds or sores.
• Breathing problems such as shortness of breath or difficulty in breathing.
• Signs of liver problems such as yellow eyes or skin, white or clay-coloured stools.
• More than one of these symptoms: abdominal pain/nausea/vomiting, dark or cloudy urine, moodiness, restlessness, confusion, shortness of breath, irregular heartbeat, unusual tiredness, fever/chills, seizure or muscle/joint pain.

Check with your healthcare team as soon as possible if you have:

• Unusual tiredness or weakness, which could be low red blood cells or hemoglobin
• Unusual bleeding or bleeding that lasts a long time
• Numbness or tingling in the extremities (feet or hands)
• Lower back pain, side pain, swelling of feet or lower legs, which could be kidney problems

Tarlatamab causes a reduction in your immune system. Discuss vaccines with your healthcare team before starting treatment.  During treatment, live vaccines should be avoided. 

Drug interactions: Tarlatamab may increase levels of certain medications, including:

• Carbamazepine
• Clozapine
• Cyclosporine
• Finerenone
• Phenytoin
• Sirolimus
• Tacrolimus
• Warfarin

Talk to your healthcare team if you are taking any of these medications.

Use in pregnancy:  There is a possibility of birth defects with tarlatamab. Effective birth control should be practiced while using this medication and for 2 months after treatment. 
Use in breastfeeding: It is not known if topotecan passes into breast milk. At this time, breastfeeding is not recommended during treatment and for 2 months after treatment has ended.