Understanding the T315I Mutation
in Ph+ CML in Chronic Phase

Gene mutations may occur in some people with Ph+ CML in chronic phase

Some patients with Philadelphia chromosome–positive chronic myeloid leukemia (Ph+ CML) in chronic phase can develop what’s known as a gene mutation. A mutation is a change in the DNA of a cell.

Mutations may cause drug resistance

One of the goals of treatment for Ph+ CML in chronic phase is to see the number of leukemic cells in the blood go down. That may not happen for some people.

If the number of leukemic cells in your body starts going up instead of decreasing, your doctor may want to see if you have become resistant to your medication. This is often called “drug resistance.” It occurs when cancer cells are not responding to a medication.

There are 2 types of drug resistance:

  • Lack of response, also called primary drug resistance: The body does not respond to a medication
  • Secondary drug resistance: Over time, the body stops responding to a medication

Learn how SCEMBLIX® (asciminib) tablets may help.

Testing for a mutation in the BCR‑ABL1 gene

In Ph+ CML in chronic phase, one of the causes of drug resistance is a mutation in the BCR-ABL1 gene.

Here are some reasons why your doctor may decide to have you tested for a gene mutation:

  • You are not responding or are no longer responding to a medication
  • You are unable to reach a treatment milestone

The name of the test your doctor may order is called a BCR‑ABL1 kinase domain mutation analysis. This test looks for mutations in the BCR-ABL1 gene that may cause certain tyrosine kinase inhibitors (TKIs) that treat Ph+ CML in chronic phase to stop working.

Identifying the T315I gene mutation

There are a number of different gene mutations that can occur in Ph+ CML in chronic phase, including a mutation called T315I. The only way to determine if you have a mutation is to undergo a BCR-ABL1 kinase domain mutation analysis. If this test shows that you have developed the T315I mutation, your doctor may consider whether to change your medication.

SCEMBLIX is approved to treat Ph+ CML in chronic phase for those with the T315I mutation. Learn more about SCEMBLIX.