An Open-Label Phase 2 Study of N-Acetyl-D-Mannosamine (ManNAc) in Subjects With Podocyte Diseases
Background: Podocyte diseases are a group of kidney conditions that include focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), and membranous nephropathy (MN). In these conditions, specialized kidney cells called podocytes, which help prevent protein from leaking into the urine, are damaged. This can result in high levels of protein in the urine and, over time, worsening kidney function. In some people, the disease may progress to kidney failure requiring dialysis or a kidney transplant. Several treatments are currently available and can be beneficial, but they may cause significant side effects and may not work well for everyone. Therefore, there is a need for safer and more effective treatments for people with these types of kidney conditions.
Objective: To test a study drug (ManNAc) in people with a podocyte disease, that includes Focal Segmental Glomerulosclerosis (FSGS), Minimal Change Disease (MCD), or Membranous Nephropathy (MN).
Eligibility: People aged 18 years and older with a podocyte disease, that includes Focal Segmental Glomerulosclerosis (FSGS), Minimal Change Disease (MCD), or Membranous Nephropathy (MN).
Design: Participants will have 5 to 6 clinic visits over 14 weeks. Two of the visits will require overnight stays for 2 or 3 nights. ManNAc is a white powder that comes in a sachet. It is dissolved in water and taken twice a day by mouth. Participants will take their first dose at the clinic. They will learn how to store ManNAc and prepare each dose. They will record their doses in a diary. They will also write down any adverse effects or troubles they have using the drug at home. During clinic visits, participants will have physical exams with blood and urine tests. They will complete questionnaires about their health, sleep habits, and fatigue symptoms. During overnight visits, participants will also have 24-hour urine collection. A study team member will call participants 1 week after the first dose to check on their health. Follow-up phone calls will then be every 2 weeks after each clinic visit. Participants may meet with a dietitian to discuss nutrition while taking the ManNAc. Participants may choose to have genetic tests.
⁃ Individuals must meet all the following inclusion criteria to be eligible to participate in this study:
• Prior kidney biopsy demonstrating FSGS, MCD, or MN obtained within 10 years prior to the screening visit.
• Age \>=18 years weighing more than 50 kg.
• If the patient is on any immunosuppressive therapy, he/she should be on them for at least 3 months prior to study evaluation and should be on a stable dose for at least 4 weeks before start of trial, with no plans to alter the regimen during 12 weeks of study period, except to stabilize levels and/or for any safety concerns.
• Subjects will be allowed to continue with standard of care (SOC) non-immunosuppressant antiproteinuric agents to include RAAS inhibitors, mineralocorticoid antagonists (MRA), sodium-glucose co-transporter-2 inhibitors (SGLT2i), non-dihydropyridine calcium channel blockers (NDHP-CCBs), Sparsentan, and glucagon-like peptide-1 (GLP-1) receptor agonists, in addition to other SOC adjuvant therapies such as diuretics, if they are able to maintain a stable dose throughout the trial. Subjects and their primary nephrologists will be encouraged to optimize their SOC treatments as much as possible prior to trial commencement. Subjects must be on a stable dose for at least 4 weeks before start of trial. Subjects should attempt to keep stable doses of both immunosuppressants and anti-proteinuric drugs throughout trial duration, to avoid confounding effects. Patients not receiving any of these SOC agents either due to allergy or intolerance will still be eligible.
• Subjects must have a spot random urine PCR of \>=2 g/g on each of 3 measurements collected on at least 2 separate days during screening and baseline period plus a 24-hr urine protein collection of \>=2 g/day. The rationale for using this degree of proteinuria is that proteinuria beyond this threshold value significantly increases the risk of progressive decline of renal functions in the absence of effective therapies to mitigate this risk. Conversely, this threshold value could also allow for the selection of a cohort of patients who are most likely to benefit from ManNAc therapy.
• Subjects with an estimated glomerular filtration rate (eGFR) \>=30 mL/min/1.73/m\^2 using the race-free CKD-EPI 2021 equation based on creatinine and cystatin-C. The rationale is that below this eGFR threshold, sialic acid, the key metabolite of ManNAc markedly accumulates and may potentially result in systemic toxicity. Prior pharmacokinetic studies have shown that renal elimination of sialic acid is primarily through glomerular filtration, and it is neither reabsorbed nor secreted in the renal tubules. Hence decline in eGFR below 30 mL/min/1.73m\^2 directly correlates with markedly rising blood sialic acid levels, in addition, these subjects may not benefit as much from ManNAc therapy as they have advanced disease pathology, which may be irreversible. Future studies with personalized precision ManNAc dosing may benefit the patient population with eGFR \<30 mL/min/1.73m\^2.
• Subjects of reproductive potential must be willing to use at least one effective form of birth control throughout the trial period, unless they have had a permanent birth control procedure/intervention including but not limited to hysterectomy, tubal ligation and/or vasectomy. These may include the following: barrier methods (such as condoms), oral or depot injection (for example, Norplant or Depo-Provera) contraception medication, and/or intrauterine devices.
• Evidence of a personally signed and dated informed consent indicating that the patient has been informed of all pertinent aspects of the study and their willingness to comply with all aspects of the study and their willingness to comply with all aspects of the study protocol, including treatment plan, laboratory tests, baseline and follow-up visits and procedures that include completion of daily diaries to record symptoms and medication intake.