Pembrolizumab injection belongs to a class of medications called monoclonal antibodies. It works by helping your immune system to slow or stop the growth and spread of cancer cells in the body. Pembrolizumab is a type of immunotherapy that blocks the PD-1 (programmed death receptor-1) receptor which helps it stop cancer cells from hiding from the immune system.

Pembrolizumab is used alone or in combination with other medicines to treat certain types of cancer such as:

• skin cancer (melanoma, Merkel cell carcinoma, squamous cell carcinoma);

• lung cancer;

• head and neck cancer;

• classical Hodgkin lymphoma;

• primary mediastinal large B-cell lymphoma;

• cancer of the kidney, bladder, and urinary tract;

• colorectal cancer;

• liver cancer;

• triple-negative breast cancer;

• cancer of the cervix or uterus;

• advanced stomach or esophageal cancer; or

• a type of cancer that laboratory testing proves to have certain specific DNA mutations.

Pembrolizumab is often given when the cancer has spread to other parts of the body, or cannot be treated with surgery or radiation, or when other cancer treatments did not work or have stopped working.

For some types of cancer, pembrolizumab is given only if your tumor tests positive for "PD-L1", or if the tumor has been tested for a specific genetic marker (including "EGFR," "ALK," "HER2/neu," or "TMB").

Your doctor will review your specific type of cancer and past treatment history and other available treatments to determine if pembrolizumab is right for you.

Pembrolizumab can change the way your immune system works, which may cause certain side effects that can lead to serious medical problems.

Pembrolizumab can cause serious or life-threatening side effects. Some side effects may need to be treated with other medicine, and your cancer treatments may be delayed. You will need frequent medical tests to help your doctor determine if it is safe for you to keep receivingthis medicine.

Call your doctor at once if you have: skin problems, vision problems, fever, swollen glands, neck stiffness, chest pain, cough, shortness of breath, muscle or joint pain, pale skin, weakness, diarrhea, severe stomach pain, blood in your stools, bruising or bleeding, dark urine, yellowing of the skin or eyes, a hormonal disorder (frequent headaches, feeling light-headed, rapid heartbeats, a deeper voice, increased thirst or urination, feeling cold, weight gain or loss), or a change in the amount or color of your urine.

Pembrolizumab is given as an infusion into a vein, usually once every 3 to 6 weeks. A healthcare provider will give you this injection.

This medicine must be given slowly over 30 minutes.

You will need frequent medical tests to help your doctor determine if it is safe for you to keep receiving pembrolizumab. Do not miss any follow-up visits.

To make sure pembrolizumab is safe for you, tell your doctor if you have ever had:

• an autoimmune disorder such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, lupus, or psoriasis;

• received or plan to receive a stem cell transplant that uses donor stem cells;

• an organ transplant;

• radiation to your chest; or

• a nerve-muscle disorder such as myasthenia gravis or Guillain-Barré syndrome.

Pembrolizumab may harm an unborn baby. You may need a pregnancy test to make sure you are not pregnant. Use effective birth control while using pembrolizumab and for at least 4 months after your last dose. Tell your doctor if you become pregnant.

Do not breastfeed while using pembrolizumab, and for at least 4 months after your last dose.

Call your doctor for instructions if you miss an appointment for your pembrolizumab injection.

In a medical setting an overdose would be treated quickly.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction to pembrolizumab (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Some side effects may occur during the injection. Tell your medical caregiver if you feel dizzy, nauseated, light-headed, itchy, sweaty, or have a headache, chest tightness, back pain, trouble breathing, or swelling in your face.

Pembrolizumab causes your immune system to attack tumor cells, but it could also attack healthy organs and tissues in your body. This could lead to serious or life-threatening side effects on your lungs, liver, pancreas, kidneys, intestines, thyroid, or adrenal glands.

Pembrolizumab may cause serious side effects. Call your doctor at once if you have:

• new or worsening cough, chest pain, shortness of breath;

• pale skin, easy bruising or bleeding;

• severe muscle pain, cramps, weakness, neck stiffness;

• double or blurry vision;

• confusion, sleep or memory problems, changes in mood or behavior, balance problems;

• numbness, tingling, burning pain, redness, rash, or blisters on your hands or feet;

• fever or flu-like symptoms, swollen glands, sores in your mouth, throat, nose, or on your genital area;

• diarrhea, severe stomach pain or tenderness, bloody or tarry stools;

• feeling sick or uneasy, with pain or swelling near your transplanted organ;

• high blood sugar = increased thirst, increased urination, dry mouth, fruity breath odor;

• kidney problems = swelling, blood in your urine, urinating less, loss of appetite, feeling tired or short of breath;

• liver problems = swelling around your midsection, right-sided upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• hormonal problems = unusual headaches, sensitivity to light, eye problems, rapid heartbeats, increased sweating, extreme tiredness, weight gain or weight loss, increased hunger or thirst, increased urination, hair loss, feeling cold, constipation, hoarse or deepened voice, dizziness, fainting, decreased sex drive; or

• low red blood cells (anemia) = pale skin, tiredness, feeling light-headed or short of breath, cold hands and feet.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common pembrolizumab side effects (some are more likely with combination chemotherapy) may include:

• nausea, vomiting, stomach pain, loss of appetite, diarrhea, constipation, weight loss;

• low blood sodium levels, abnormal thyroid, liver and kidney function tests;

• low blood cell counts;

• tingling or numbness in your hands or feet, loss of movement in the arms and legs;

• bleeding;

• pain and burning when you urinate;

• fever, headache, feeling weak or tired, dizziness, trouble sleeping;

• cough, hoarse voice, feeling short of breath;

• changes in your sense of taste, dry skin and dry eyes;

• itching, hair loss, rash or blisters on your hands or feet;

• increased blood pressure;

• pain in your muscles, bones, or joints; or

• mouth sores or swelling around your mouth, nose, eyes, throat, intestines or vagina.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all other cancer treatments you are receiving.

Other drugs may interact with pembrolizumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.