Treatment Options for Multiple Myeloma and Other Plasma Cell Disorders

Treating solitary plasmacytomas

Solitary plasmacytomas are single plasma cell tumors. Most often they develop in a bone, but they can also start in other body tissues (such as the lungs or other organs), where they are called solitary extramedullary (or extraosseous) plasmacytomas. 

These tumors are most often treated with radiation therapy. Sometimes the tumor might be removed with surgery first, as part of the testing to determine what it is. But even then, radiation therapy is often given to the area afterward, especially if the tumor is in a bone. Surgery might also be needed to stabilize a bone that has been weakened by a tumor.

Medicines aren't usually part of the treatment for a plasmacytoma, unless it progresses at some point to multiple myeloma.

Treating smoldering multiple myeloma

Smoldering myeloma has some features of active multiple myeloma, but it doesn't cause symptoms.

People with smoldering myeloma are generally grouped based on their risk of the disease progressing to active myeloma. This is based on the results of the bone marrow biopsy and certain lab tests.

People in the low-risk group often do well for years without treatment, so they're typically watched closely without starting treatment right away. They usually have regular doctor visits and tests to check if the disease has progressed to active myeloma. These are typically done every 3 to 6 months for a while, but the time between visits and tests might be extended over time. If the disease does progress to active myeloma at some point, treatment (as described below) can be started at that time.

For people with high-risk smoldering myeloma, options might include close monitoring (similar to what's done with low-risk disease) or treatment with medicines, such as lenalidomide, with or without dexamethasone. This can help lower the risk of the disease progressing to active myeloma and can help prevent organ damage in some people. If the myeloma does progress at some point, treatment options would be the same as those for active myeloma (as described below).

Treating active (symptomatic) multiple myeloma

Medicines are the main type of treatment for multiple myeloma. Usually different types of medicines are used together, as this offers a better chance to keep the myeloma under control. The choice of medicines depends on many factors, including:

• Which risk group the myeloma is in (high risk or standard risk), which is based mainly on certain gene or chromosome changes in the myeloma cells
• If a person is eligible for (and is considering) a stem cell transplant
• A person's age, overall health, and preferences

Initial treatment for active multiple myeloma

The first treatment for nearly all people with myeloma is several months of medicines. This is sometimes referred to as induction therapy, as the goal is to induce a remission of the myeloma.

Most often, 3 or 4 different types of drugs are given. Many combinations of drugs can be used. Some of the more common combinations used to treat myeloma include:

• Bortezomib, lenalidomide, and dexamethasone
• Carfilzomib, lenalidomide, and dexamethasone
• Daratumumab, lenalidomide, and dexamethasone
• Daratumumab, bortezomib, lenalidomide, and dexamethasone
• Isatuximab, bortezomib, lenalidomide, and dexamethasone
• Bortezomib, cyclophosphamide, and dexamethasone

Many other combinations of drugs might be options as well.

While 4 drugs might keep the myeloma under control for longer than 3 drugs, it's also likely to result in more side effects. Regimens that contain 4 drugs are more likely to be used for people with high-risk myeloma and who are otherwise fairly healthy.

People with multiple myeloma typically get a medicine to help keep the bones strong as well, such as a bisphosphonate (pamidronate or zoledronic acid) or denosumab. People might also get other types of supportive treatments to help prevent or treat symptoms from the myeloma.

Treatment options for standard-risk myeloma

After several months of induction treatment, stem cells are usually collected from the patient's blood, if they might get a stem cell transplant at some point.

At this point, the options for people with standard-risk myeloma might include:

• Having an autologous stem cell transplant, (for people who are eligible, known as an early stem cell transplant)
• Continuing to get the same medicines, for up to about a year or until the myeloma progresses, and then getting a stem cell transplant (known as a delayed or late stem cell transplant)
• Continuing to get the same medicines, for up to about a year in total or until the myeloma progresses, for people who can't get or don't want a stem cell transplant

After any of these approaches, long-term maintenance therapy, most often with a single drug such as lenalidomide, might be recommended.

Treatment options for high-risk myeloma

People with high-risk myeloma are more likely to get a 4-drug regimen for their induction treatment. After several months of this, stem cells are usually collected from their blood, if they might get a stem cell transplant at some point.

Because of the higher risk of the myeloma progressing, doctors often advise doing a stem cell transplant at this time, if a person can have it. This is usually an autologous transplant (either a single transplant or a tandem/double transplant, in which two transplants are done, typically 3 to 6 months apart). Less often, an allogeneic transplant might be considered for some people.

For people who can't get a stem cell transplant, treatment with the same medicines is usually continued as long as it's effective, for up to about a year in total.

After either of these approaches, long-term maintenance therapy, most often with lenalidomide and/or bortezomib, is typically recommended.

If the myeloma doesn't respond or stops responding to treatment

While multiple myeloma is very hard to cure, medicines are often very good at keeping it under control or even shrinking it for long periods of time. Still, sometimes myeloma might not respond well to treatment, or it might start growing again during treatment (or after treatment).

If this happens, other options can be tried. There are many types of medicines to treat myeloma. Which treatment is best depends on many of the same factors used to decide on the first treatment, as well as others, such as:

• Which medicines have been used to treat the myeloma before
• How well the myeloma responded to the medicines
• If the myeloma is likely to respond to the same medicines again
• When in the course of treatment the myeloma progresses or comes back
• If a stem cell transplant is now an option

Usually if the myeloma progresses during the initial (induction) treatment, other combinations of medicines can be tried. A stem cell transplant might be another option.

Newer medicines and treatments, such as bispecific T-cell engagers (BiTEs) and CAR T-cell therapy, might also be options at some point. While these are usually reserved for later lines of treatment (after others have been tried), doctors are now studying their use earlier in the course of treatment as well.

Myeloma tends to get harder to treat as more lines of treatment have been tried. At any time, taking part in a clinical trial studying a newer treatment might be a good option for some people.

Regardless of which treatments are being used, people with myeloma can often be helped by getting supportive treatments as well.