Ixazomib is an oral medication used to treat multiple myeloma, a type of blood cancer. This medication is typically administered as part of a combination therapy, often alongside lenalidomide and dexamethasone, for patients who have received at least one prior treatment. Ixazomib targets and disrupts the growth of cancerous cells, contributing to the overall therapeutic strategy for multiple myeloma.
Understanding Multiple Myeloma
Multiple myeloma is a cancer originating in plasma cells, a type of white blood cell found in the bone marrow. These cells normally produce antibodies to fight infections. In multiple myeloma, these plasma cells become abnormal and multiply uncontrollably, crowding out healthy blood cells in the bone marrow.
This uncontrolled growth can lead to various complications, including bone damage, kidney problems, and a weakened immune system. The abnormal plasma cells also produce an ineffective antibody (paraprotein) that does not properly fight infection and can accumulate in the body, causing further issues. The disease is often called “multiple” myeloma because it affects various parts of the body where bone marrow is present.
How Ixazomib Targets Cancer Cells
Ixazomib functions as a proteasome inhibitor, a drug class that interferes with a cellular process essential for cancer cell survival. Cells, including cancer cells, have a system called the ubiquitin-proteasome pathway. This pathway acts as a waste disposal and recycling center for proteins, breaking down old or damaged proteins and maintaining cellular balance.
Cancer cells rely on this waste removal system due to their rapid growth and high protein turnover. By inhibiting the proteasome, ixazomib causes a buildup of unwanted proteins within the myeloma cells. This accumulation of proteins becomes toxic to the cancer cells, leading to their dysfunction and death. Ixazomib specifically and reversibly binds to the proteasome’s β5 subunit, preventing it from carrying out its normal function.
Administering Ixazomib and Managing Side Effects
Ixazomib is administered as an oral capsule, taken once a week on the same day and at the same time for three weeks, followed by a one-week rest period within a 28-day cycle. It is taken on an empty stomach, at least one hour before or two hours after food, and should not be cut, crushed, or chewed. This medication is part of a combination regimen that includes lenalidomide and dexamethasone.
Patients taking ixazomib may experience various side effects, with gastrointestinal issues such as diarrhea, constipation, nausea, and vomiting being common. These symptoms can range from mild to severe, and patients should report them to their healthcare provider for management. Low blood counts, including thrombocytopenia (low platelet count) and neutropenia (low white blood cell count), are also frequently observed. Thrombocytopenia, while common, is usually manageable and reversible, and rarely leads to significant bleeding or drug discontinuation.
Other potential side effects include nerve problems like tingling, numbness, pain, or weakness, often affecting the hands or feet, known as peripheral neuropathy; symptoms should be reported for dose adjustments. Rashes are also common, and any new or worsening skin reactions, severe blistering, or mouth sores should be reported immediately to the healthcare team. Swelling in the face, limbs, or feet (peripheral edema) can occur, and fluid retention may be managed with diuretics. Additionally, back pain is a common side effect, and pain relief can be discussed with a doctor.
Key Considerations During Treatment
Close monitoring by a healthcare team is important throughout ixazomib treatment to manage side effects and ensure patient safety. Regular blood tests are performed to check blood cell counts (including platelets and neutrophils) and liver function due to the risk of liver injury. If liver enzyme levels are elevated, a dose reduction or temporary cessation of ixazomib may be necessary.
Dose adjustments may also be required based on kidney or liver function. For patients with severe kidney impairment or those on dialysis, the starting dose is typically reduced from 4 mg to 3 mg. Similarly, for moderate or severe liver impairment, a reduced starting dose of 3 mg is recommended. Ixazomib is not removed by dialysis, so its administration timing does not need adjustment relative to dialysis sessions.
Patients should also be aware of drug interactions. Certain medications, particularly strong inducers of the CYP3A enzyme, such as rifampin, carbamazepine, and phenytoin, can significantly decrease the effectiveness of ixazomib by reducing its levels in the body. Therefore, concomitant administration of ixazomib with strong CYP3A inducers should be avoided. Open communication with the healthcare team about all medications, supplements, and any new or worsening symptoms is important for safe and effective treatment.