ProKidney is an investigational cell therapy under development for individuals living with chronic kidney disease (CKD). This therapy, known as rilparencel (or REACT®), is being explored as a potential approach to preserve kidney function. It aims to offer a different path for patients facing limited options beyond preparing for dialysis. The treatment is a first-in-class cellular therapy candidate that uses a patient’s own cells.
The Science Behind ProKidney
ProKidney’s therapy uses “autologous” cells, meaning they are derived from the patient’s own body. This approach involves isolating and multiplying specific kidney cells, referred to as Selected Renal Cells (SRCs). SRCs are a mixture primarily consisting of epithelial cells from the kidney’s proximal tubules and glomeruli, along with other cell types.
Once these expanded SRCs are reintroduced into the kidney, they are believed to engage in natural healing processes. Animal models suggest that this cell-based therapy may mimic aspects of fetal kidney development, potentially initiating a cascade of events that could stabilize or improve kidney function. The cells are thought to help reduce inflammation and fibrosis, which are common causes of kidney damage and progression of CKD.
By mitigating these damaging processes, the therapy seeks to preserve the function of the remaining healthy kidney tissue. This unique mechanism aims to halt disease progression or, in some cases, lead to meaningful improvement in kidney function, differentiating it from treatments that only slow decline. The autologous nature of the therapy also means that a patient would not require a lifetime of immunosuppressive drugs to prevent rejection, which is often necessary for organ transplants.
The Treatment Process
The treatment journey with ProKidney’s therapy begins with a minimally invasive kidney biopsy. This standard procedure, typically guided by imaging like CT scans or ultrasound, involves taking a small tissue sample from the patient’s kidney cortex. This initial biopsy typically yields between 50,000 to 100,000 cells.
The collected cells are then transported to a specialized laboratory for processing. Here, these Selected Renal Cells (SRCs) undergo a period of ex vivo culture and expansion. Over several weeks, these cells are multiplied significantly, growing into a therapeutic dose of approximately two to three billion cells.
The final step involves the reintroduction of the expanded cells back into the patient’s kidney. This is performed as a percutaneous, minimally invasive injection into the kidney cortex, usually under CT guidance in an outpatient setting. Patients typically receive two injections, with the first often administered into the biopsied kidney, followed by a second injection into the other kidney approximately three months later.
Intended Patient Population
ProKidney’s investigational therapy is specifically being studied for patients diagnosed with chronic kidney disease (CKD) primarily caused by type 2 diabetes. This focus addresses a significant cause of kidney disease progression.
The current clinical trials are focused on individuals with more advanced stages of CKD, specifically Stage 3b and Stage 4. Stage 3b CKD indicates moderate to severe loss of kidney function, while Stage 4 CKD signifies severe reduction in kidney function.
The patient criteria for these trials also include accompanying albuminuria, which is an elevated level of albumin protein in the urine, with a urine albumin-to-creatinine ratio (UACR) typically ranging from 300 to 5000 mg/g. These specific patient criteria apply to the ongoing clinical trials and do not represent an approved use of the therapy, as it remains investigational.
Clinical Trial Status and Efficacy Data
ProKidney’s rilparencel is an investigational therapy that is currently undergoing late-stage clinical trials, specifically Phase 3 studies, and has not yet received approval from regulatory bodies like the FDA. The therapy has been granted Regenerative Medicine Advanced Therapy (RMAT) designation by the FDA, which facilitates its development and review.
The primary goal of the therapy, as demonstrated in earlier trials, is to preserve kidney function by slowing the rate of decline or even stabilizing it. The success of the therapy is primarily measured by changes in the estimated Glomerular Filtration Rate (eGFR) slope. The eGFR is a calculation that provides an estimate of how well the kidneys are filtering waste from the blood; a declining eGFR slope indicates worsening kidney function.
In a Phase 2 trial (REGEN-007), one group of patients who received two injections of rilparencel showed a statistically significant improvement in their annual eGFR slope, with a 78% reduction in the rate of kidney function decline. Their average annual decline improved from -5.8 mL/min/1.73m² before treatment to -1.3 mL/min/1.73m² after the last injection. Topline data for the accelerated approval pathway from the ongoing Phase 3 PROACT 1 trial is anticipated in the second quarter of 2027.