Self-administration of Subcutaneous Elranatamab in the Patients' Homes.

The goal of this open label, phase two, prospective, non-randomized, sponsor-initiated explorative trial is to test self-administration of subcutaneous Elranatamab in the patients' homes in patients with relapsed multiple myeloma exposed to at least one proteasome inhibitor, one IMID and one anti CD-38 antibody. The main question\[s\]it aims to answer are: * To evaluate the safety of self-administration of Elranatamab in the patients' own homes using registrations of occurrence of CRS, Immune effector cell-associated neurotoxicity syndrome (ICANS) and infections. * To evaluate the feasibility of self-administration of Elranatamab in the patients´ own homes by registration of discarded doses, planned doses administered at home and doses diverted from the patients' homes to the outpatient clinic. * To elucidate the perspectives of patients and their caregivers of self-administration of Elranatamab at home by interviewing both parties at end of treatment (EOT). * To elucidate the perspectives of involved healthcare professionals in a focus group interview at end of study (EOS). * To clarify time spent on self-administration at home compared to administration at the outpatient clinic by registering time consumption for patients, caregivers and healthcare professionals. * To evaluate the patients' QoL during self-administration using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) together with the Functional Assessment of Cancer Therapy-Cognitive (FACT Cognitive). * To clarify if self-administration in the patients' homes leads to additional unplanned contacts with the healthcare system as a whole by weekly registration of any unplanned contacts. * To determine financial costs of self-administration at home compared to administration at the outpatient clinic from the perspectives of patients, caregivers and the healthcare system by collecting data on lost earnings, transport costs and salary costs. * To evaluate the feasibility of the use of an electronic registration of side effects prior to treatment by comparing electronic patient reported outcome (PRO) data to registrations performed by nurses in the outpatient clinic during telephone consultations. Participants will be asked to * register time spend * answer PRO-questionnaires * weekly register any unplanned contact to the heathcare system * be interviewed