Chronic Myeloid Leukemia (CML) is a type of blood cancer that begins in the bone marrow—the spongy tissue inside your bones where blood cells are made. About 1 in every 565 people in the US will develop CML during their lifetime, making it a relatively common type of leukemia, especially among older adults.
With CML, your bone marrow produces too many abnormal white blood cells, a key part of your immune system. These abnormal cells crowd out the healthy red blood cells and platelets your body needs to stay healthy. Over time, this imbalance can cause symptoms like tiredness, infections, and even an enlarged spleen.
Currently, the only known cure for CML is an allogeneic stem cell transplant, which involves using healthy stem cells from a donor. However, this treatment is complicated and can have serious side effects, so doctors usually save it for when other cancer treatments aren't effective.
Newer treatments like targeted therapies have made managing CML easier, greatly improving patients' quality of life. Ongoing clinical trials also give patients access to promising new therapies and personalized treatment options, offering hope for even better outcomes in the future.
CML (chronic myelogenous or chronic granulocytic leukemia) is a cancer of the bone marrow and blood cells. It begins with a genetic change (a mutation in the DNA sequence) in one of the bone marrow’s stem cells – a somatic mutation that occurs during your lifetime, not something you inherit. This mutation creates an abnormal gene known as BCR-ABL1 (often due to a chromosomal swap called the Philadelphia chromosome).
The BCR-ABL1 gene acts like a stuck “on” switch, causing the bone marrow to overproduce abnormal white blood cells (a key part of the immune system). Over time, these leukemia cells crowd out the normal production of other blood cells. Apart from rare exposure to high-dose radiation, there are no clear risk factors or preventable causes for CML.
As CML develops, the overgrowth of abnormal white blood cells disrupts normal blood cell balance. The bone marrow may struggle to produce enough healthy cells. For example, red blood cell levels can fall (causing anemia and fatigue), and platelets may also be affected. Many people with CML develop an enlarged spleen, which can cause a feeling of fullness or discomfort in the left upper abdomen.
In the early stages, CML often causes a few noticeable problems and might be found in routine blood tests. When symptoms do occur, they can include fatigue, night sweats, weight loss, or abdominal fullness from the enlarged spleen.
If CML isn’t treated, it can progress to aggressive phases. In the advanced blast crisis phase, CML behaves like acute leukemia with very high levels of immature cells and severe symptoms. Without treatment, CML can reach this dangerous stage within a few years.
CML is usually confirmed with specialized tests on blood and bone marrow. A routine blood test (CBC) showing an extremely high white cell count is often the first clue. If CML is suspected, a blood or bone marrow biopsy and genetic analysis are done to look for the Philadelphia chromosome or the BCR-ABL1 fusion gene.
Detecting this specific genetic marker confirms the diagnosis. Doctors may also use imaging (such as an ultrasound) to check if the spleen is enlarged. Knowing whether the disease is in the chronic or more advanced phase helps guide treatment planning.
Treating Chronic Myeloid Leukemia depends on which stage of the disease you're in. Each phase requires different approaches.
In the chronic phase, treatment usually starts with a tyrosine kinase inhibitor (TKI) medication. TKIs specifically target the abnormal cells caused by the BCR::ABL1 gene mutation. Common TKIs used for initial treatment include:
Doctors carefully monitor how well you respond to these medications. If a TKI isn’t working effectively, your doctor might:
Some people have a specific mutation known as T315I. If you have this mutation, your doctor may prescribe:
In the accelerated phase, your leukemia cells start changing faster, which may make them more resistant to treatments. Doctors usually recommend visiting a specialist cancer care center for this stage. Before starting new treatments, doctors perform genetic tests (such as BCR::ABL1 mutation analysis) to determine the most effective therapy.
Treatment options for this phase include:
The blast crisis phase of CML is the most severe and resembles acute leukemia. Treatment should be handled by specialists at dedicated cancer centers.
Doctors typically perform:
Treatment strategies for blast crisis include:
The treatment your doctor recommends will depend on several important factors:
It's important to discuss the following with your cancer care team:
If you're pregnant, considering pregnancy, or breastfeeding, discuss your treatment carefully with your doctor. Oral CML treatments can harm a developing baby. Stopping treatment during pregnancy can also increase the risk of relapse. Your healthcare team can help you carefully weigh your options.
If your cancer doesn't respond to initial treatments, your doctor will suggest alternative approaches, including newer medications or clinical trials designed explicitly for resistant (refractory or relapsed) CML.
Clinical trials test promising new medications and treatment strategies that aren't yet widely available. They often focus on personalized therapies that target specific genetic mutations within leukemia cells, potentially improving quality of life and overall outcomes.
Today, participating in clinical trials is becoming easier and more convenient, thanks to decentralized trial models offered by platforms like Science 37. Decentralized trials allow you to participate from your own home or local clinic, minimizing travel, reducing disruptions to your daily routine, and making advanced care accessible no matter where you live. With virtual check-ins, medication delivered directly to your doorstep, and digital tools to report your progress, platforms like Science 37 remove barriers that previously prevented many people from joining clinical trials.
If your current treatment isn't working as hoped, or you want to explore newer options, talk to your doctor about clinical trials. Participating might help you and contribute to better treatment options for others facing CML in the future. You can also check out organizations like the American Cancer Society for additional resources.
