Clinical Trial of CDX-1135 in Pediatric and Adult Patients With Dense Deposit Disease

Inclusion Criteria: Among other criteria, patients must be 1. Patient and/or parent/legal guardian (as appropriate) must give written informed consent 2. Four (4) years of age or older 3. Must have DDD, confirmed by renal biopsy within 6 months of study enrollment (Confirmation by University of Iowa investigators is required). If the patient is post transplant, the repeat renal transplant biopsy must show C3 dominant glomerulonephritis, and the patient must have a history of known DDD in the native kidney 4. Signs of abnormal complement pathway activity 5. Serum creatinine level must be abnormal 6. Screening lab values criteria: 1. Hgb ≥ 9.0 g/dL 2. Platelets ≥ 100,000/mm\^3 3. ALT and AST ≤ 3.0 x upper limit of normal 4. C3 serum \<50% of the lower limit of normal 5. 24 hour urine protein \>1000 mg/day, or urine protein:creatinine ratio \>1.0 7. Both male and female patients of childbearing potential enrolled must use adequate birth control during the trial and for 1 month after stopping study drug 8. Willing and able to comply with study procedures, including pre-study vaccinations (meningitis, haemophilus and pneumococci) and agree to a renal biopsy at Week 13 and at the end of the study 9. Any anti-proteinuric medications (eg, angiotensin converting enzyme inhibitors, angiotensin II receptor blockers) must be at a stable dose for 4 weeks prior to first dose of CDX-1135 Exclusion Criteria: Among other criteria, patients must not be 1. Dialysis or a low estimated glomerular filtration rate \<30 ml/min/1.73m\^2 over a 4-week period prior to Screening 2. Active or untreated systemic bacterial infection 3. Pregnant or lactating 4. Rituximab therapy (unless discontinued with B cell levels and immunoglobulin levels normalized by study entry) 5. Immunosuppressive therapies (except for low dose steroids \[≤10 mg per day\] given for non-DDD related conditions such as asthma). Exceptions will be made for renal transplant patients, who may receive any appropriate therapies as needed to maintain the transplant (i.e., to prevent rejection) 6. Treatment with any complement inhibitor within 3 months of study entry or any other investigational drug, device, or experimental procedure within 4 weeks prior to enrollment 7. For renal transplant patients only: histology findings of treatable rejection (i.e. that the usual transplant physician would seek to treat). Chronic allograft nephropathy is not exclusionary provided the patient's glomerular filtration rate meets other entry criteria 8. Preexisting condition with an association as a potential cause of DDD (i.e., Monoclonal Gammopathy of Undetermined Significance) or an alternate glomerular disease 9. Cancer except for adequately treated and cured basal or squamous cell skin cancer, curatively treated in situ disease, or other cancer that the patient has been disease-free for ≥ 5 years 10. Myocardial infarction within 1 year of screening, congestive heart failure, arrhythmia persistent on medication at screening or chronic lung disease 11. Known HIV, Hepatitis B or Hepatitis C 12. Any medical or psychological condition that would increase the patient's risk by being in this study or would interfere with interpretation of the study