A Study to Assess Renal Function Response to Treatment in Patients With Relapsed Multiple Myeloma and Creatinine Clearance

Inclusion Criteria:

1. Patients of both genders, aged equal or more than 18 years.
2. Patients with documented relapsed multiple myeloma according to International Myeloma Working Group ( IMWG) criteria.
3. Patients with documented renal damage defined as creatinine clearance \<50 ml / min / 1.73 m2 (CrCl \<50ml / min / 1.73m2).
4. Patients to whom the researcher decides to initiate anti-myeloma treatment for relapse with one or more agents according to clinical practice \*.
5. Patients who consent in writing after it has been clearly explained to them the nature and purpose of the study (written informed consent).
6. Subject with any of the following characteristics (at least one of the 2 following options must be Yes):

   * Subjects who have not previously participated in the study
   * Subjects who have previously participated in the study, who meet all the inclusion criteria again and to whom none of the exclusion criteria apply, and whose current relapse is consecutive to the relapse that prompted their initial inclusion in the study.

     * The decision to prescribe treatment will be clearly dissociated from the decision to include the patient in the study

       * Clarification is provided as to the aim of the study, which is to encompass all relapse subcategories included in the International Myeloma Working Group consensus document published in 2006. Therefore, all patients with clinically relapsed multiple myeloma, who are in relapse following a complete response or in progression (including refractory cases) as defined in point 8.1 and in table 4 of the protocol, are considered eligible candidates for participation in the EPA-MIR 50 study, as long as they meet all the other criteria

Exclusion Criteria:

1. Patients who are participating in an interventional clinical trial \* or who refuse to participate in the study.
2. Patients with CrCl \<50 ml / min / 1.73m2 due to a cause other than multiple myeloma properly documented at the discretion of the investigator \*.

   * The inclusion of patients who are participating in another observational study is permitted.