RRMM stands for relapsed/refractory multiple myeloma, a stage of the blood cancer multiple myeloma where the disease has either returned after a period of improvement or stopped responding to treatment. Most people with multiple myeloma will eventually reach this stage, since the cancer tends to cycle through periods of remission and relapse over the course of the disease.
How Relapsed Differs From Refractory
The two words in RRMM describe different situations. “Relapsed” means the cancer came back after at least 60 days of improvement following treatment. The myeloma cells start multiplying again, protein markers in the blood climb, and symptoms may return. “Refractory” means the disease never responded to a particular treatment, or stopped responding while the patient was still on it. Many patients are both relapsed and refractory at the same time: their cancer returned, and it no longer responds to the drugs that previously worked.
Doctors track progression using specific lab markers. A diagnosis of progressive disease requires at least a 25% increase from the lowest measured value in one or more indicators: the abnormal protein the cancer produces (called M-protein) in blood or urine, or the percentage of cancerous plasma cells in a bone marrow sample. These aren’t numbers you need to memorize, but they explain why your care team monitors blood work so closely between treatments.
Why Multiple Myeloma Keeps Coming Back
Multiple myeloma is described as a “remitting and relapsing” disease. After initial treatment, most patients enter remission, sometimes for years. But a small population of myeloma cells typically survives, resistant to the drugs that killed the rest. Over time, those surviving cells multiply, protein levels rise, and the cancer reappears.
Each successive relapse tends to follow a pattern: the response to the next treatment is usually shorter and less deep than the one before it. A first remission might last several years, while later remissions may last only months. Eventually the disease becomes resistant to multiple drug classes, which is when the situation becomes most challenging. That said, many patients live for decades after their initial diagnosis, cycling through several effective treatments over that time.
What Relapse Feels Like
A relapse doesn’t always announce itself with obvious symptoms. Many patients learn about it from routine blood tests showing rising M-protein levels before they feel any different. When symptoms do appear, they mirror the problems myeloma causes in general: bone pain (especially in the back or ribs), fatigue, frequent infections, kidney problems, or unexplained weight loss. Your oncologist will time the start of new treatment carefully, aiming to intervene before these complications develop but not so early that you’re on unnecessary therapy.
Triple-Class Refractory Disease
As patients move through multiple treatments, oncologists classify how refractory the disease has become based on which drug classes have stopped working. The three main drug classes used against myeloma are proteasome inhibitors, immunomodulatory agents, and anti-CD38 monoclonal antibodies. When a patient’s cancer no longer responds to all three, it’s called triple-class refractory (TCR) myeloma.
Triple-class refractory patients have historically had especially poor outcomes because these three classes form the backbone of standard myeloma treatment. Once all three fail, the remaining options were limited until recently. This is the group driving the most urgent need for new therapies, and fortunately, several have arrived in the past few years.
How RRMM Is Treated Now
Treatment for RRMM depends on which drugs have already been tried, how the patient responded, and how many lines of therapy they’ve been through. The newer treatments generating the most attention fall into two broad categories: CAR-T cell therapy and bispecific antibodies. Both harness the immune system to attack myeloma cells in ways that bypass the resistance built up against older drugs.
CAR-T cell therapy involves collecting a patient’s own immune cells, engineering them in a lab to recognize a protein on myeloma cells called BCMA, and infusing them back. It’s a one-time treatment that requires a hospital stay. In the CARTITUDE-1 trial, patients who had been through a median of six prior treatments achieved a median overall survival of about five years (60.7 months), a remarkable result for such heavily treated patients. Response rates in CAR-T studies are high, often above 95%, though the cancer does eventually return for most people.
Bispecific antibodies work on a similar principle but are given as ongoing injections rather than a one-time infusion. These drugs act as a bridge, physically connecting immune cells to myeloma cells so the immune system can destroy them. Talquetamab, one of the approved options, targets a different protein (GPRC5D) and has shown overall response rates between 67% and 74% in heavily pretreated patients. Median overall survival in one cohort reached 34 months, with some groups doing even better.
In July 2025, the FDA approved linvoseltamab, another bispecific antibody targeting BCMA, for adults who have been through at least four prior lines of therapy including all three major drug classes. This approval specifically addresses the triple-class refractory population.
Side Effects of Newer Therapies
Both CAR-T therapy and bispecific antibodies can cause cytokine release syndrome (CRS), a reaction where the activated immune system floods the body with inflammatory signals. Symptoms range from mild fever and chills to, in rare cases, dangerously low blood pressure. Medical teams monitor closely for this, especially in the first days after treatment, and it’s usually manageable.
Low blood cell counts are the most common serious side effect across both treatment types. Infections are also a significant concern: in the talquetamab studies, infections of any severity occurred in 61% to 78% of patients depending on the dosing schedule, though serious infections were mostly limited to the early treatment cycles. Talquetamab also causes some unique side effects related to the protein it targets, including changes in taste, skin and nail changes, and oral dryness. A small number of patients developed balance problems, though this was uncommon.
What the Outlook Looks Like
The prognosis for RRMM has improved substantially. Even five years ago, patients who had exhausted the three main drug classes faced median survival measured in months. The five-year survival data now emerging from CAR-T trials, combined with the expanding roster of bispecific antibodies, has shifted expectations. The goal of treatment at this stage isn’t typically cure, but extending life and maintaining quality of life through successive effective therapies.
How well any individual patient does depends heavily on how many prior treatments they’ve received, how aggressive the cancer’s biology is, and which new therapies are still available to try. Patients diagnosed today benefit from a treatment landscape that looks very different from even a few years ago, with multiple immune-based options that work through entirely new mechanisms. Researchers are also exploring whether some of these newer therapies could be used earlier in the disease course, which could change the RRMM landscape further.