ProKidney’s cell therapy for kidney disease failed to demonstrate a clinically significant preservation of kidney function in one part of a phase 2 study, but the biotech has pointed to the trial’s other more successful cohort as evidence the asset remains on track.
The product, called rilparencel or REACT, is an autologous cell therapy created by identifying progenitor cells in a patient’s biopsy. A team formulates the progenitor cells for injection into the kidney, where the hope is that they integrate into the damaged tissue and restore the function of the organ.
The North Carolina-based biotech evaluated rilparencel in the REGEN-007 trial of 49 patients with diabetes, chronic kidney disease (CKD) and an estimated glomerular filtration rate (eGFR) of 20-50 mL/min/1.73m²—a signifier of reduced kidney function.
These patients were randomized into two groups, the first of which received two rilparencel injections three months apart. These patients saw an annual improvement in their so-called “eGFR slope” —the rate of kidney function decline—of 78%, which the company branded “statistically significant and clinically meaningful.”
The second cohort initially received a single rilparencel injection and only received a second if they saw a sustained decline in kidney function. The 50% improvement in eGFR slope seen in this group was not statistically significant, said ProKidney, who still suggested that it showed “evidence of a dose response.”
No serious adverse events were linked to treatment with rilparencel, the company pointed out.
ProKidney said it has a meeting set for this summer to get the FDA’s sign-off on using eGFR slope as the surrogate endpoint in an ongoing U.S.-based phase 3 study of rilparencel, dubbed PROACT 1. The company hopes that the late-stage study, which uses the same dosing regimen as the more successful phase 2 cohort, will set up rilparencel for accelerated approval.
“We are very encouraged by the REGEN-007 topline results that demonstrated a robust improvement in eGFR slope following treatment with rilparencel in Group 1 as well as evidence of a dose response in Group 2,” ProKidney’s CEO Bruce Culleton, M.D., said in the July 8 release.
“These data bolster our confidence in the design of our ongoing phase 3 PROACT 1 study, given the similarity between the dosing regimen in REGEN-007 Group 1 and PROACT 1,” Culleton added. “It is also worth noting that 15 of the 24 patients in Group 1 (63%) met key phase 3 PROACT 1 inclusion criteria, and similar efficacy results were observed in this subgroup compared to the full Group 1 results.”
Investors seemed convinced, sending ProKidney’s microcap stock up 48% to 89 cents in premarket trading Tuesday, up from a Monday closing price of 60 cents.
At one point, ProKidney had been running an international phase 3 trial, dubbed PROACT 2, of rilparencel alongside the U.S.-based PROACT 1. But the biotech scrapped PROACT 2 in September 2024 after concluding that rilparencel was eligible for FDA approval under an expedited pathway if PROACT 1 alone proves to be a success.