Understanding Proteasome Inhibitor Treatments

Here are some shared risks you can consider going over with your doctor.

You'll usually have lab work done often at the start of treatment, sometimes weekly. These tests track your blood counts, kidney and liver function, and how your myeloma is responding.

Pregnancy and breastfeeding. Proteasome inhibitors aren't suggested during pregnancy or breastfeeding. If pregnancy is possible, talk with your care team about birth control before starting treatment.

Choosing the right treatment

You and your doctor will weigh the pros and cons of each medicine to choose the best treatment plan. If something isn't working for you, speak up early.  If side effects become difficult to manage, your doctor may:

• Adjust your therapy
• Change the schedule
• Suggest another medicine

What Is Bortezomib (Boruzu, Velcade)?

Bortezomib was the first proteasome inhibitor approved for multiple myeloma. It remains a top choice for many people starting treatment. It works by blocking the proteasome, which helps trigger cell death and also makes it harder for myeloma to stick to bone marrow cells.

How you take it

• Shot under the skin (most common) or through a vein
• Usually once or twice a week
• Given as part of a 21- or 28-day cycle
• Often used for four to eight cycles early in treatment

Your doctor may adjust the dose, timing, or length of treatment based on how your cancer responds and how well you tolerate the medicine. Many side effects improve or go away when the dose is lowered or treatment is paused.

What the research shows

Studies regularly show that adding bortezomib to combination treatment improves how well myeloma responds. It may also help delay disease progression compared with older treatment approaches.

These benefits have been seen in both people who go on to have a stem cell transplant and those who don't. When bortezomib is used alongside immune-based drugs, more people have a deeper response to treatment.

The medicine's benefits can also include very low or undetectable levels of myeloma. Clinical trials also show longer progression-free survival, meaning the disease stays under control for a longer period before it worsens.

Side effects of bortezomib

Some side effects more closely linked to bortezomib include:

• Peripheral neuropathy (numbness, tingling, burning, or pain in the hands and feet)
• Low blood pressure (can cause dizziness or feeling like you might pass out)

Tell your doctor right away if you notice new nerve symptoms. When caught early, neuropathy often improves with dose changes or schedule adjustments.

Who should use caution

Bortezomib may not be the best choice if you have:

• Had a serious allergic reaction to this drug
• Severe nerve damage
• Significant liver, lung, or heart disease

You may still be able to take bortezomib if your nerve problems or other conditions, such as diabetes or heart disease, are milder. Your care team will watch symptoms closely and adjust treatment as needed.

What Is Carfilzomib (Kyprolis)?

Carfilzomib is the second proteasome inhibitor approved to treat multiple myeloma. It targets the same protein-recycling system as bortezomib.

But carfilzomib can bind more tightly and work longer inside the cancer cell. This stronger effect can often help control myeloma when other treatments become less effective.

Doctors may also choose carfilzomib if you have high-risk multiple myeloma. High-risk disease means the cancer has certain chromosome changes that make it grow faster or come back sooner after treatment.

How you take it

• Given through a vein once or twice a week
• Most often given in a 28-day cycle
• Continued in cycles as long as it's helping and side effects are manageable

Once-weekly schedules are now commonly used. They lower the number of clinic visits and work as well as older, more frequent schedules.

What research shows

Studies show that carfilzomib can help keep myeloma under control longer if your cancer has returned after early treatment (relapsed). When used as part of combination therapy, it often leads to deeper responses than other proteasome inhibitors.

Research also suggests carfilzomib may be especially helpful if you're newly diagnosed (just starting treatment) and have a high-risk disease. That's when a stronger approach early on may improve disease control.

Side effects of carfilzomib

Compared to bortezomib, carfilzomib is less likely to cause nerve damage. But it carries a higher risk of heart-related side effects, such as:

• High blood pressure
• Heart rhythm changes such as irregular heartbeats
• Heart failure, especially if you're older or already have heart disease

In clinical trials, some people also had:

• Swelling in the hands and feet
• Shortness of breath
• Kidney problems, including kidney failure
• High blood pressure in the lungs

These side effects tend to appear early in treatment, sometimes within the first few months. Because of this, while you're on carfilzomib, your care team may more often test your:

• Blood pressure
• Heart function
• Lung function
• Fluid status
• Kidney labs

Who should use caution

Carfilzomib may not be the best choice if you have:

• Serious heart, lung, or kidney disease
• Uncontrolled high blood pressure
• Recent heart attack
• A history of serious heart rhythm problems

Some people with stable heart or kidney conditions may still be able to take carfilzomib, but you'll need careful monitoring. If side effects become a problem, speak up. Your doctor can:

• Slow the infusion
• Adjust the dose
• Change how often you get treatment
• Switch you to a different treatment

What Is Ixazomib (Ninlaro)?

Ixazomib is a proteasome inhibitor taken by mouth. It's the first medication in this class available as a pill. That can make treatment easier for some people.

Like other proteasome inhibitors, ixazomib blocks the cell's protein-recycling system. This leads to a buildup of waste inside myeloma cells and can slow or stop their growth.

Your doctor may suggest ixazomib along with other medicines after you've tried at least one prior therapy. In some cases, it may also be used as part of a clinical trial or when an oral treatment is preferred.

How you take it 

• Taken as a pill, usually once a week
• Given in 28-day cycles (three weeks on, one week off)
• Often taken with other medicines, such as dexamethasone and lenalidomide
• Taken on an empty stomach, at least one hour before or two hours after food

It's important to follow dosing instructions closely, including timing around meals. Let your care team know if you miss a dose or have side effects.

What research shows

Studies show that adding ixazomib to standard oral treatment can help slow disease growth in people whose cancer has already been treated.

Ixazomib has also been studied as a maintenance treatment after using one therapy. While it may be an option in some situations, it's not commonly used for maintenance compared with other medicines.

Side effects of ixazomib

Most people handle ixazomib well. Compared with other proteasome inhibitors, it tends to cause fewer nerve problems. While you can still get peripheral neuropathy, only a small number of people in clinical trials said their nerve pain, weakness, or numbness was so bad it got in the way of daily life.

Common side effects include

• Nausea and vomiting
• Diarrhea
• Constipation
• Swelling in your hands or feet
• Back pain or muscle aches

Rare risks to know about include:

• Severe rash
• Big drops in platelets, which can make bleeding more likely
• Worsening liver function
• Eye problems like blurry vision, dry eye, or pink eye

Your doctor will check your lab tests regularly and ask about your symptoms. If side effects become difficult to manage, they may adjust the dose or change the treatment schedule.

How Much Do Proteasome Inhibitors Cost?

Cancer treatment can be expensive, but most people don't have to pay full price for medicine. The actual cost depends on several things, including your insurance coverage and where you get treatment.

Let your doctor know if you have trouble paying for treatment. Many cancer centers have social workers, patient navigators, or financial counselors.

These groups can also help:

• International Myeloma Foundation
• Multiple Myeloma Research Foundation
• HealthWell Foundation
• Blood Cancer United (formerly the Leukemia & Lymphoma Society)
• PAN Foundation

Drug companies may also offer copay help. Patient support programs for brand-name medicines include Takeda Oncology Here2Assist (for Ninlaro) and Amgen Support (for Kyprolis).

5 Things to Consider When Choosing Proteasome Inhibitors

Your care team will help guide treatment decisions, but understanding the basics can help you feel more prepared. Here are a few things to keep in mind as you talk through your options.

Which medicine fits your situation best. All proteasome inhibitors work in a similar way, but they aren't the same. Your doctor looks at how active your myeloma is, your lab results, and whether you've had treatment before when choosing a specific medication.

Side effects that matter most for you. Each medicine has a different side effect pattern. For example, nerve problems may steer doctors away from bortezomib, while heart or blood pressure concerns can affect whether carfilzomib is a good fit. Be sure your care team knows about all your health conditions.

How treatment fits into daily life. Some proteasome inhibitors require regular clinic visits. Others can be taken at home. Think about travel time, work schedules, caregiver support, and what feels manageable from week to week.

Your overall health, not just the cancer. Conditions like diabetes, heart disease, kidney problems, or lung disease can affect which treatments are safest. Even issues that seem unrelated to cancer can matter, so be open about your full medical history.

Your goals and the long-term plan. Let your care team know if side effects are hard to manage or something doesn't feel right. Talking openly helps them adjust treatment as your needs change. It's also worth asking whether a clinical trial makes sense now or later.