The Effect of Daratumumab in Patients with Monoclonal Gammopathy of Renal Significance (MGRS) in Finland

Inclusion Criteria:

1. Males or females ≥ 18 years of age

2. Subject has provided informed consent prior to initiation of the study or subject'slegally acceptable representative has provided informed consent prior to the studywhen the subject has any kind of condition that, in the opinion of the investigator,may compromise the ability of the subject to give written informed consent.

3. Renal biopsy confirmed MGRS-disease

• Renal biopsy must not be older than 3 months before informed consent. However,if renal biopsy is older than 3 mo and the study team is convinced that majorhistological changes have not occurred, a biopsy older than that canexceptionally be accepted.

• Renal transplant patients are allowed

4. Amount of proteinuria ≥ 500 mg/24 h OR eGFR ≥ 20 ml/min prior to the study

5. Previous anticlonal treatment is allowed if deemed ineffective

Exclusion Criteria:

1. Myeloma or systemic AL amyloidosis (smoldering myeloma sized plasma cell clone isallowed when in association with a documented MGRS condition and AHL amyloidosis andAH amyloidosis are included)

2. Cancer that requires treatment,

3. MGRS related to B-cell malignant disorders,

4. Known HIV infection, active hepatitis C infection (subjects with hepatitis C thatachieve a sustained virologic response after antiviral therapy are allowed), orhepatitis B infection (subjects with hepatitis B surface antigen or core antibodythat achieve sustained virologic response (PCR negativity in HBVNh) with antiviraltherapy are permitted with a requirement for regular monitoring for reactivation forthe duration of treatment on the study),

5. Pregnancy or breastfeeding,

6. Cyclophosphamide within 6 months of enrollment, or oral high-dose prednisone orequivalent within 6 weeks of enrollment;

• prednisone or its equivalent at a dosage of ≤10 mg daily for a conditionunrelated to MGRS (e.g. asthma or gout) allowed.

• mycophenolate mofetil (MMF), calcineurin inhibitors (CNI) or azathioprinetreated patients are eligible if proteinuria is not improving or if kidneyfunction is declining despite treatment with these medications. Once therapywith daratumumab started, these medications need to be discontinued unless theyare used as immunosuppressive medication due to renal transplantation.

7. In patients who previously received rituximab, reconstitution of B cells (CD19normalized, Ly-B-CD19 lab.code 8329) required.

8. Inability to use daratumumab and to comply with the study protocol as assessed bytreating nephrologist and/or hematologist (e.g. severe psychiatric illness, severelung disease, known allergy to daratumumab)