What is APL?

• Acute promyelocytic leukaemia (APL), also called APML is a rare subtype of AML.
• APL can cause serious bleeding and clotting complications and needs to be diagnosed and treated urgently.
• APL treatment will usually be started before a diagnosis is confirmed.
• Symptoms of APL include bleeding easily or for longer, blood clots or increased infections.
• Between 90 to 95% of people with APL will go into remission (where there is no sign of leukaemia left) after their first treatment. There are other treatment options available if APL comes back. APL only comes back very rarely.

Acute promyelocytic leukaemia (APL, also called APML) is very rare. In the UK, around 180 people are diagnosed with it every year.

APL happens when some of your white blood cells don’t develop properly. In APL, two chromosomes get mixed up, and a gene from each chromosome join to form a new, faulty gene. In the most common type of APL, this gene is called PML/RARa.

It is this faulty gene which causes the blood cells to not develop properly, causing APL. This gene cannot be passed on to children.

The affected cells don’t grow into fully functioning white blood cells. These cells are called promyelocytes. They build up in the blood and the bone marrow (the spongy tissue inside some of our bones where blood cells are made), leaving less room for healthy blood cells to grow and work.

This means your body may not have enough healthy red blood cells, white blood cells and/or platelets. White blood cells fight infection, red blood cells carry oxygen, and platelets help to to stop bleeding.

APL develops quickly (it’s acute), but most people respond well to treatment and will go into remission.

APL needs to be treated immediately as it can cause serious bleeding and clotting complications. Treatment will usually start as soon as APL is suspected.

While the cause of APL is not known, there are some things that may affect how likely you are to develop it.

• Age – although APL can occur at any age, it’s most common in adults over the age of 40.
• Previous cancer treatment – APL can occasionally develop in some people after chemotherapy for another condition. This type of APL is also known as therapy-related acute myeloid leukaemia (tAML) or secondary APL.

If you are diagnosed with APL, you may want to know more about your prognosis or your outlook − what's likely to happen in the future.

Your outlook is individual to you and depends on many factors.

The biggest risk for people with APL is the risk of bleeding and clotting complications in the initial stage. Once you get through this stage, the outlook for people with APL is usually very good. Most people will respond well to treatment and will go into remission.

We have general information about things that might affect your prognosis, but everyone is different. Your hospital team will answer any questions that you may have about your outlook.

People cope differently with diagnosis and information. If you want to know about your outlook, your hospital team are the best people to ask. Your hospital team can also refer you for psychological support.