Relapsed Refractory Multiple Myeloma (RRMM) Glossary

Monoclonal: A clone or duplicate. Myeloma cells are derived from a “monoclone,” a single malignant plasma cell in the bone marrow. The type of myeloma protein produced is also monoclonal , a single form rather than many forms (polyclonal). The important practical aspect of a monoclonal protein is that it shows up as a sharp spike “M-spike” on the protein electrophoresis test. See “M-spike.”

Monoclonal antibody: An antibody manufactured in a lab rather than produced in the human body. Monoclonal antibodies are specifically designed to find and bind to cancer cells and/or immune system cells for diagnostic or treatment purposes. Monoclonal antibodies can be used alone, or they can be used to deliver drugs, toxins, or radioactive material directly to tumor cells.

Monoclonal protein (myeloma protein, M-protein): An abnormal protein produced by myeloma cells that accumulates in and damages bone and bone marrow. It is found in unusually large amounts in the blood and/or urine of myeloma patients. See “Monoclonal” and “M-spike.”

MRD-negative: Minimal residual disease-negative. Depending on the test, not even one myeloma cell found in 100,000 or 1,000,000 sampled bone marrow plasma cells. See “Minimal residual disease.”

Multi-drug resistance (MDR): A resistance to treatment caused by a buildup of P-glycoprotein in the outer cell membrane of the myeloma cells.

Multiple myeloma: A cancer of the bone marrow plasma cells, white blood cells that make antibodies. The cancerous plasma cells are called myeloma cells.

Myeloablation: A severe form of myelosuppression, in which the consequence of high-dose chemotherapy or radiation is the complete or near-complete destruction of the bone marrow’s ability to produce blood cells. See “Myelosuppression.”

Myelosuppression: A decrease in the production of red blood cells, platelets, and some of the white blood cells.

Neurotoxicity: Neurologic toxicity is when exposure to toxic substances changes the normal activity of the nervous system.

Neuropathy: A feeling of numbness, tingling, burning, and/or pain caused by nerve damage. See “Peripheral neuropathy.”

Overall response rate (ORR): In myeloma clinical trials, the percentage of patients whose monoclonal protein decreased by at least 50% in response to treatment.

Overall survival (OS): The median number of individuals in a group who are alive after a particular duration of time. OS is often used as a measure of treatment efficacy in clinical trials. The lengthening duration of OS in myeloma trials makes it a difficult endpoint to use, leading to the effort to validate minimal residual disease (MRD) status as a new endpoint.

Palliative treatment: A treatment designed to improve the quality of life by relieving pain and symptoms of disease but not intended to alter the course of the disease.