Pembrolizumab
A humanized anti-PD-1 antibody that frees T cells to attack tumors, used for melanoma, lung cancer and many other cancers.
Drug card
- How it works
- Blocking the PD-1 off switch on T cells so they attack cancer cells
- Used for
- Melanoma, advanced or after surgery
- Non-small cell lung cancer
- Head and neck squamous cell cancer
- Classical Hodgkin lymphoma
- Known for
- Immune attack on healthy organs
- Underactive thyroid (hypothyroidism)
- Its name
- -mab means a monoclonal antibody; -zumab means a humanized monoclonal antibody
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does pembrolizumab work?
Pembrolizumab is a humanized IgG4 antibody that binds PD-1 on T cells and stops PD-L1 and PD-L2 from engaging it. Released from this inhibitory signal, which some tumors exploit by making extra PD-L1, T cells multiply, make cytokines and attack the cancer.
Uses
What is pembrolizumab used for?
- Melanoma, advanced or after surgery
- Non-small cell lung cancer
- Head and neck squamous cell cancer
- Classical Hodgkin lymphoma
- Urothelial (bladder) cancer
- Colorectal cancer, MSI-high or mismatch repair-deficient
Side effects
Side effects of pembrolizumab
- Immune attack on healthy organsKnown forSerious
- Underactive thyroid (hypothyroidism)Known for
- Overactive thyroid or thyroiditis
- Lung inflammation (pneumonitis)Serious
- Colitis with diarrheaSerious
- Liver inflammation (hepatitis)Serious
- Pituitary or adrenal failure (low cortisol)Serious
- New type 1 diabetes, sometimes with ketoacidosisSerious
- Kidney inflammation (nephritis)Serious
- Severe skin reactions (SJS, TEN)Serious
- Muscle, bone and joint pain
- Infusion reactionsSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Liver tests, creatinine and thyroid function are checked at baseline and periodically during treatment.
- Immune-related effects can appear at any time, even after stopping; the drug is withheld and corticosteroids are given.
- Transplant recipients may reject the organ, and allogeneic stem cell transplant before or after it can have fatal complications.
- Pregnancy: it can harm the fetus, so effective contraception is needed.
Good to know: One of its uses depends on a tumor feature rather than where the cancer began: any solid tumor that is MSI-high or mismatch repair-deficient.
Remember it
A way to remember it
PINCHES
- P
- Pneumonitis
- I
- Insulin-dependent (type 1) diabetes
- N
- Nephritis
- C
- Colitis
- H
- Hepatitis
- E
- Endocrine glands: thyroid, pituitary, adrenal
- S
- Skin rash and itching
Written for biofideX
Its name
-mab means monoclonal antibody
Older names show the source: -ximab chimeric, -zumab humanized, -umab human. WHO stopped adding that part in 2017 and dropped -mab in 2021; new names end in -tug, -bart, -ment or -mig.
-zumab means humanized monoclonal antibody
Humanized antibodies are human apart from the mouse loops (CDRs) that bind the target, as in trastuzumab (against HER2) and pembrolizumab (against PD-1). WHO stopped adding this part in 2017.
- Every drug name stem
Its class
PD-1 checkpoint inhibitors
PD-1 is an inhibitory receptor on activated T cells: when PD-L1 or PD-L2 binds it, the T cell is switched off, and some tumors make extra PD-L1 to dodge attack. These monoclonal antibodies bind PD-1 and block both ligands, so the brake is released and T cells attack the cancer. The same loss of tolerance lets T cells turn on healthy organs, which causes the immune-related side effects.
Easily mixed up with CD20-targeted antibodies and HER2-targeted antibodies.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Targeted therapy and the immune system
Pembrolizumab is one of 13 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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