A prospective, multicentre, post-authorisation observational study. The objective of this study is assess the response of renal function in clinical practice to anti-multiple myeloma therapy in patients with relapsed MM and CrCl <50 mL/min/1.73 m2.

Prospective, multicentre, post-authorisation observational study. Study population: Patients with relapsed multiple myeloma and with CrCl <50 mL/min/1.73 m2, for whom the investigator decides to start a new line of anti-myeloma treatment as per normal clinical practice. The decision to prescribe treatment will be clearly disassociated from the decision to include the patient in the study.

300 patients are expected to be recruited (225 for Group 1 and 75 for Group 2) from 40 sites (approximately 7-8 patients for each site). Patients will be included consecutively in the study.

The inclusion will be stratified to ensure the presence of all stages of renal impairment (RI) in two groups:

Documentation of 300 patients is planned (a maximum of 225 in group 1 and a minimum of 75 in group 2) at 40 sites (approximately 7-8 patients per each site). The patients will be included in the study in a consecutive manner.

In order to ensure the correct stratification of the sample group a real time central registry will be kept for the patients included in each group. Once the required number of patients for one of the groups is completed, inclusion in that group will be closed at all sites, keeping inclusion for other groups open, and so on until the entire sample size is complete.

Primary objective: To assess the response of renal function in clinical practice to anti-multiple myeloma therapy in patients with relapsed MM and creatinine clearance <50 mL/min/1.73 m2 (CrCl <50 mL/min/1.73m2).

The prospective follow-up period will cover two phases:

1. Treatment phase: covers the entire time the patient is receiving the first anti-myeloma treatment for relapse* for which he/she is included in this study.

2. Follow-up phase: A 36-month extension period after the end of the first anti-myeloma treatment for relapse for which he/she was included in the study.

   • Any change in therapeutic regimens, for example, discontinuation or addition of a drug (except for changes in dose for some of the initial drugs) will mark the end of the treatment phase and the passing of the patient to the follow-up phase. In case of temporary interruptions in treatment under 30 days (or of any duration if the reason for interruption is toxicity) the patient will continue in the treatment phase, provided that the initial treatment regimen for the relapse it resumed.

Secondary objectives:

• To describe the clinical and demographic characteristics of patients with relapsed multiple myeloma and CrCl <50 mL/min/1.73 m2.
• To assess the response rate of renal function in clinical practice to anti-multiple myeloma therapy in patients with relapsed multiple myeloma and CrCl <50 mL/min/1.73 m2.
• To assess the response of renal function based on the therapeutic regimens administered.
• To explore the concordance of the kidney function response and that of the myeloma in the clinical practice to the anti-myeloma treatment between consecutive relapses in the same patient.
• To assess time-dependent response parameters.
• To analyse the safety of treatments administered in clinical practice.
• To describe the use of resources associated with anti-myeloma therapy in clinical practice that can be measured financially, and to explore the possible differences between the various therapeutic regimens administered.

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.

Patients with relapsed /refractorymultiple myeloma and with CrCl <50 mL/min/1.73 m2, for whom the investigator decides to start a new line of anti-myeloma treatment as per normal clinical practice. The decision to prescribe treatment will be clearly disassociated from the decision to include the patient in the study.