The aim of this study is to assess the clinical efficacy and safety of the anti-BCMA/CD3 bispecific antibody teclistamab (Tecvayli®) in a prospective, real-life setting in Belgium.

To assess the clinical efficacy and safety of teclistamab (Tecvayli®) in relapsed/refractory multiple myeloma patients who have received at least 3 prior lines of treatment and who will receive teclistamab (Tecvayli®) as the next treatment. Patients will be followed up prospectively until the end of study (24 months/2 years), or until disease progression, withdrawal of consent death or loss to follow-up, whichever occurs first. Each patient will have a monthly follow-up from baseline until 6 months of treatment with teclistamab. Then, data will be collected every 3 months until the end of study.

Inclusion Criteria:

• Age 18 years or older
• Written informed consent
• Has a diagnosis of relapsed and refractory multiple myeloma
• Has already received at least three previous treatments
• Is refractory to at least 1 proteasome inhibitor, at least 1 immunomodulatory agent, and an anti-CD38 monoclonal antibody
• Evidence of disease progression on the last line of therapy, based on determination of response by the IMWG response criteria
• Anticipated to start treatment with teclistamab per routine clinical care or has started with teclistamab treatment ≤14 days before intended screening visit

Exclusion Criteria:

• Has participated in a teclistamab trial (teclistamab or control arm) or teclistamab Single Patient Request (SPR) program
• Has started teclistamab treatment >14 days before intended screening visit.

100 patients with relapsed or refractory multiple myelome who will be treated with teclistamab (Tecvayli®)