This is a non-interventional, prospective study of participants with MM relapses. This study will assess the low detection rate of biochemical relapses which will improve routine clinical practices and management of participants with MM in real world practice.~The study will enroll approximately 350 participants. The data will be collected both prospectively and/or retrospectively at the specialized care (hematology) and will be recorded into electronic case report forms (e-CRFs) of the electronic data capture (EDC) system. All the participants will be assigned to a single observational cohort:~• Participants With MM~This multi-center study will be conducted in the Russian Federation. The overall duration of the study will be approximately 4 years. The overall time for treatment and follow-up period will be approximately 2.5 years for each participant.
The main aim of this study is to learn how long it takes for people with MM to have a relapse after their first treatment. Not all participants will have a relapse during the study.~Participants will visit their clinic every 3 months and be treated according to their clinic's standard practice.~The study sponsor will not be involved in how participants are treated but will provide instructions on how the clinics will record what happens during the study.