Tyrosine Kinase Inhibitors (TKIs): How They Work, Uses, and Side Effects

Oct 29

9 min read

Updated: 6 days ago

Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026 · How we review

Quick Answer: What are tyrosine kinase inhibitors?

Tyrosine kinase inhibitors (TKIs) are targeted cancer medicines, taken as pills or liquid, that block tyrosine kinase enzymes cancer cells use to grow and divide. They treat cancers such as chronic myeloid leukemia, non-small cell lung cancer, HER2-positive breast cancer and kidney cancer. TKIs cannot cure cancer, but they can bring long-term remission and longer life. [1]

What the research says

Imatinib kept most people with chronic myeloid leukemia alive at 10 years. In a trial of people newly diagnosed with chronic-phase chronic myeloid leukemia, followed for a median of 10.9 years, the estimated 10-year overall survival on imatinib was 83.3%, and 82.8% reached a complete cytogenetic response. Serious drug-related side effects were uncommon and mostly happened in the first year. (Hochhaus et al., N Engl J Med, 2017) [2]
A newer TKI helped people with EGFR-mutated lung cancer live longer. In 556 people with untreated advanced EGFR-mutated non-small cell lung cancer, median overall survival was 38.6 months with osimertinib versus 31.8 months with older EGFR TKIs (gefitinib or erlotinib). Severe side effects were similar: 42% versus 47%. (Ramalingam et al., N Engl J Med, 2020) [3]
Some people in deep remission can stop a TKI under close monitoring. Among 755 people with chronic myeloid leukemia who had taken a TKI for at least 3 years and stayed in deep molecular response for at least 1 year, 61% remained free of molecular relapse 6 months after stopping and 50% at 24 months. No serious adverse events were reported. This decision belongs to your hematologist: never stop a TKI on your own. (Saussele et al., Lancet Oncol, 2018) [4]

Key takeaways

Tyrosine kinase inhibitors are a type of targeted therapy that blocks enzymes controlling cell growth and division. [1]
TKIs come as pills or liquid, usually taken once or twice a day. [1]
They treat solid tumors and blood cancers, including lung, breast, kidney and gastrointestinal cancers, melanoma and leukemia. [1]
Side effects range from fatigue and fever to rare, life-threatening skin reactions, depending on the drug. [1]
Over time, some cancers change and stop responding to a TKI. [1]

What are tyrosine kinase inhibitors?

Tyrosine kinase inhibitors are targeted therapies that treat many kinds of cancer by blocking substances inside cancer cells that control how fast those cells grow and divide. [1]

Tyrosine kinases are enzymes that help manage how cells work, including cell signaling, growth and how often cells divide. Some TKIs are used to treat cancer by blocking these enzymes so cancer cells stop growing. [1]

TKIs cannot cure cancer. They can, however, put cancer into long-term remission or help people with certain cancers live longer. [1]

How do tyrosine kinase inhibitors work?

Tyrosine kinase inhibitors work by disrupting the process that tells your cells when to grow and divide. [1] That process has two main players:

Player	What it is	What it does
Growth factors	Chemicals that control cell growth	Flip the switch that turns tyrosine kinases on
Tyrosine kinases	Enzymes inside your cells	Signal the cell to start dividing, then turn off

In healthy cells, tyrosine kinases turn on and off as needed. Cells keep dividing only until the tyrosine kinases switch off. [1]

In some cancers, a mutation creates an abnormal tyrosine kinase that switches on and never switches off. A TKI blocks that abnormal signal and flips the switch back to "off." [1]

Diagram comparing a healthy cell, a cancer cell with a tyrosine kinase stuck on, and a cancer cell treated with a TKI that switches the signal off. Image: rinnit.com

How do tyrosine kinase inhibitors treat chronic myeloid leukemia?

Tyrosine kinase inhibitors treat chronic myeloid leukemia (CML) by switching off an abnormal enzyme that makes bone marrow cells multiply out of control. [1]

CML is a blood cancer that starts in the blood-forming myeloid stem cells in your bone marrow. When these cells mutate, they make an abnormal tyrosine kinase that turns on and never turns off. [1]

Without an "off" switch, the myeloid cells divide uncontrollably. This makes it hard for your bone marrow to produce the other blood cells and platelets your body needs. A TKI blocks the abnormal signal so the cancerous cells stop dividing. [1]

	Healthy myeloid cell	CML cell	CML cell on a TKI
Tyrosine kinase	Turns on and off normally	Stuck on	Blocked
Cell division	Controlled	Uncontrolled	Slowed or stopped
Effect on bone marrow	Makes all blood cells normally	Crowded, fewer healthy cells	Room to recover

What cancers do tyrosine kinase inhibitors treat?

Tyrosine kinase inhibitors treat several kinds of cancer, including solid tumors and blood cancers. [1]

Cancer	Type	Learn more
HER2-positive breast cancer	Solid tumor	Breast cancer guide
Non-small cell lung cancer	Solid tumor	Non-small cell lung cancer guide
Chronic myeloid leukemia	Blood cancer	See the section above
Chronic lymphocytic leukemia	Blood cancer	Chronic lymphocytic leukemia guide
Gastrointestinal stromal tumors	Solid tumor	GIST guide
Kidney cancer	Solid tumor	Kidney cancer guide
Melanoma	Solid tumor	Melanoma guide
Waldenström macroglobulinemia	Blood cancer	Waldenström macroglobulinemia guide

How many tyrosine kinase inhibitors are approved?

As of November 2022, the U.S. Food and Drug Administration had approved 50 tyrosine kinase inhibitors for solid tumors, including lung, breast and colon cancer, and 8 for blood cancers such as leukemia. [1]

TKI approvals (as of November 2022)	Number
For solid tumors (lung, breast, colon and others)	50
For blood cancers (such as leukemia)	8
For both tumors and certain blood cancers	4
Cancer types treated by imatinib, the first FDA-approved TKI	7

Infographic of eight cancers treated with tyrosine kinase inhibitors and FDA approval numbers: 50 for solid tumors, 8 for blood cancers, 4 for both, and imatinib treating 7 cancer types. Image: rinnit.com

How are tyrosine kinase inhibitors taken?

Tyrosine kinase inhibitors are taken by mouth as a pill or liquid, usually one or two doses a day, depending on the cancer type and stage. [1]

How long do you need to take a tyrosine kinase inhibitor?

The length of tyrosine kinase inhibitor treatment depends on your situation. For example, people with chronic myeloid leukemia may take the medication for the rest of their lives. [1]

What are the side effects of tyrosine kinase inhibitors?

Tyrosine kinase inhibitor side effects vary widely because TKIs treat a wide range of cancers, and each drug group affects the body differently. [1]

Side effect group	Examples	Linked to TKIs that target
Skin reactions	Mild rashes, up to life-threatening Stevens-Johnson syndrome / toxic epidermal necrolysis	Non-small cell lung, breast, colorectal and pancreatic cancer
Heart and kidney effects	High blood pressure and protein in the urine (proteinuria)	Non-small cell lung and colorectal cancer
General effects	Fatigue, fever, weight loss or weight gain	Varies by drug

Ask your care team which side effects are most likely with your specific TKI. Many TKIs can harm an unborn baby and interact with other medicines, supplements and grapefruit, so tell your team if you could become pregnant and before taking anything new. [1]

Infographic of tyrosine kinase inhibitor side effects: common effects, skin and blood pressure effects that depend on the TKI group, and coping tips. Image: rinnit.com

What are the benefits of tyrosine kinase inhibitors?

The main benefit of tyrosine kinase inhibitors is targeting cancer cells while largely sparing healthy cells, which is the core idea behind all targeted therapies. [1]

They help people live longer. TKIs slow cancer down and extend survival for many cancer types. [1]
They changed the outlook for CML. TKIs turned chronic myeloid leukemia from a life-threatening disease into a chronic illness that medication can manage. [1]
They offer an option when other treatments fail. TKIs may be used when other cancer treatments, such as chemotherapy, are not effective. [1]
They work on some returning or spreading cancers. TKIs can treat certain cancers that come back after treatment or have spread. [1]

Can cancer stop responding to tyrosine kinase inhibitors?

Cancer can stop responding to tyrosine kinase inhibitors because some cancers change over time. When that happens, the TKI that once stopped the cancer's growth no longer works. [1]

Your care team watches for signs that treatment isn't working or that the cancer has spread, and will discuss next steps with you. [1]

How can you make tyrosine kinase inhibitor treatment easier?

Knowing what to expect is one of the best ways to make tyrosine kinase inhibitor treatment easier. Most side effects are mild, but rarely they can be life-threatening. [1]

Challenge	What can help
Fatigue (very common)	Get as much sleep and rest as you can
Appetite changes, weight loss or gain	Ask a nutritionist for help with meals and menu plans
Disruption to daily life	Find ways to stay organized during treatment
Ongoing symptoms and side effects	Consider palliative care, specialized care that helps you live more comfortably

Support after and during treatment can also include cancer rehabilitation.

When should you call your doctor during tyrosine kinase inhibitor treatment?

You should call your doctor during tyrosine kinase inhibitor treatment if you notice new or worsening symptoms, any side effects your care team told you to watch for, or signs the cancer may be spreading. [1]

Seek emergency care right away for a painful, spreading rash, blisters or peeling skin, which can signal a rare but life-threatening skin reaction. [1]

Questions to bring to your next appointment:

Which side effects are most likely with my TKI?
How long will I need to take this medication?
What signs would show the treatment is not working?
Who should I call if a side effect starts?

Conclusion

Tyrosine kinase inhibitors are targeted cancer pills that switch off the signals telling cancer cells to divide. They treat cancers from leukemia to lung, breast and kidney cancer, and for chronic myeloid leukemia they turned a life-threatening disease into a manageable one. TKIs do not cure cancer, can cause side effects and may stop working over time, so regular check-ins with your care team matter. [1]

Want to understand your full treatment picture? Read our guide to targeted therapy, compare it with immunotherapy, and save or print this page to bring to your next oncology appointment.

FAQ

Are tyrosine kinase inhibitors chemotherapy?

Tyrosine kinase inhibitors are a type of targeted therapy, not standard chemotherapy. TKIs block specific enzymes that drive cancer cell growth and are designed to spare healthy cells. [1]

Can tyrosine kinase inhibitors cure cancer?

Tyrosine kinase inhibitors cannot cure cancer. TKIs can put cancer into long-term remission or help people with certain cancers live longer. [1]

How long do you take a tyrosine kinase inhibitor?

Tyrosine kinase inhibitor treatment length depends on your cancer and situation. People with chronic myeloid leukemia, for example, may take a TKI for the rest of their lives. [1]

What are the most common side effects of tyrosine kinase inhibitors?

Common side effects of tyrosine kinase inhibitors include fatigue, fever and weight loss or weight gain. Some TKIs can also cause skin rashes, high blood pressure or protein in the urine. [1]

Which cancers are treated with tyrosine kinase inhibitors?

Tyrosine kinase inhibitors treat cancers including HER2-positive breast cancer, non-small cell lung cancer, chronic myeloid and chronic lymphocytic leukemia, gastrointestinal stromal tumors, kidney cancer, melanoma and Waldenström macroglobulinemia. [1]

Why might a tyrosine kinase inhibitor stop working?

A tyrosine kinase inhibitor may stop working because some cancers change over time. When the cancer changes, the TKI that stopped its growth may no longer be effective. [1]

When should you seek emergency care while taking a TKI?

Seek emergency care while taking a TKI if you develop a painful, spreading rash, blisters or peeling skin. These can be signs of Stevens-Johnson syndrome or toxic epidermal necrolysis, rare but life-threatening reactions. [1]

Can tyrosine kinase inhibitors interact with other medicines or foods?

Yes. Many TKIs interact with other medicines, supplements and grapefruit, which can raise or lower drug levels. Tell your care team and pharmacist about everything you take.

Should you take a tyrosine kinase inhibitor with food?

It depends on the drug. Some TKIs must be taken on an empty stomach and others with food, so follow the instructions for your specific medicine.

Can you take a tyrosine kinase inhibitor during pregnancy?

Most TKIs can harm an unborn baby. Use effective birth control during treatment and talk with your care team before trying to get pregnant.

References

Cleveland Clinic. Tyrosine Kinase inhibitors (TKIs): Uses & Side Effects. Cleveland Clinic. Last updated May 12, 2023. https://my.clevelandclinic.org/health/treatments/24984-tyrosine-kinase-inhibitors
Hochhaus A, Larson RA, Guilhot F, et al. Long-Term Outcomes of Imatinib Treatment for Chronic Myeloid Leukemia. N Engl J Med. 2017;376(10):917-927. PMID 28273028. https://doi.org/10.1056/NEJMoa1609324
Ramalingam SS, Vansteenkiste J, Planchard D, et al. Overall Survival with Osimertinib in Untreated, EGFR-Mutated Advanced NSCLC. N Engl J Med. 2020;382(1):41-50. PMID 31751012. https://doi.org/10.1056/NEJMoa1913662
Saussele S, Richter J, Guilhot J, et al. Discontinuation of tyrosine kinase inhibitor therapy in chronic myeloid leukaemia (EURO-SKI): a prespecified interim analysis of a prospective, multicentre, non-randomised, trial. Lancet Oncol. 2018;19(6):747-757. PMID 29735299. https://doi.org/10.1016/S1470-2045(18)30192-X

Disclaimer

This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Always talk with your doctor or oncology team before starting, changing or stopping any medication.