How quickly does Imbruvica (ibrutinib) work?

• In some people, very good partial clinical responses to Imbruvica may occur within three to six months.
• Imbruvica is usually given until disease progression or unacceptable toxicity occurs, or in the case of graft vs host disease, recurrence of an underlying malignancy.
• The average duration of Imbruvica therapy in clinical trials has been around 41 months (range, 2–51 months).
• High lymphocyte counts are a common and safe side effect that has been reported in 57% to 69% of people receiving Imbruvica in clinical trials. These resolve in over 94% of people within 14 weeks, and are not a reflection of treatment response or cancer progression.

In some people, very good partial clinical responses to Imbruvica (ibrutinib) may occur within three to six months.

During initial treatment with Imbruvica, it is not uncommon to see an increase in white cell counts (lymphocytes).

High lymphocyte counts have been reported in up to 57% to 69% of people in clinical trials. These resolved after 12 weeks in 95% of patients after ibrutinib was seen in 77 (57%) patients in group 1. This lasted for 12 to 14 weeks and resolved in 94% to 95% of these patients. Response to treatment and survival without cancer progression was similar in people with a high lymphocyte count during initial therapy and those without.

Most people are kept on Imbruvica indefinitely regardless of clinical response. This is a common treatment strategy for people with certain types of leukemia and solid tumors because often when the treatment agent is stopped, symptoms can reappear and lymph nodes enlarge within a relatively short period, particularly if patients have not been taking Imbruvica for very long or if they have tried many other previous treatments.

The average duration of Imbruvica therapy in clinical trials has been around 41 months (range, 2–51 months). In people who have stopped Imbruvica, the average survival after treatment discontinuation was 8 months.

What is the starting dose of Imbruvica?

The recommended starting dose for adults for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and Waldenström’s macroglobulinemia (WM) is 420mg once daily.

For chronic graft-versus-host disease the dose depends on the patient's age:

• Adults and children 12 years and older: 420mg once daily.
• Children aged 1 to less than 12 years of age: 240 mg/m² taken orally once daily (up to a dose of 420mg).

Dosages may need reducing if toxicities occur.

Imbruvica is usually given until disease progression or unacceptable toxicity occurs, or in the case of graft vs host disease, recurrence of an underlying malignancy.

What are the most common side effects with Imbruvica?

The most common side effects reported with Imbruvica include:

• Back pain
• Bruising
• Chest pain, atrial fibrillation, atrial flutter
• Diarrhea
• Heartburn
• High blood pressure
• Infection
• Lowered blood counts
• Muscle aches
• Tiredness
• Blood in the urine.

These are typically experienced when starting Imbruvica, but usually resolve within 2-3 months. Older people are more at risk of side effects including bruising. In general, Imbruvica is well tolerated.

What is Imbruvica?

Imbruvica (ibrutinib) is a targeted medicine that works by inhibiting the enzyme Bruton tyrosine kinase (BTK), which is part of a crucial signaling pathway in certain cancers, especially B-cell leukemias and lymphomas.

By blocking this pathway Imbruvica triggers the death of cancer cells. Imbruvica may be used in the treatment of

• Waldenstrom's macroglobulinemia
• Chronic lymphocytic leukemia
• Small lymphocytic lymphoma
• Chronic graft-versus-host disease.