Vertex Pharmaceuticals Reports Positive Phase 3 RAINIER Results for Povetacicept in IgA Nephropathy Published in NEJM
Vertex Pharmaceuticals Incorporated has announced the publication of Phase 3 RAINIER trial results for povetacicept in the New England Journal of Medicine (NEJM), alongside the presentation of the findings at the American Society of Nephrology (ASN) Kidney Week 2026 in Denver, Colorado. The company also announced continued advancement of its clinical research program evaluating povetacicept for immunoglobulin A nephropathy (IgAN), a chronic and progressive kidney disease that can lead to kidney failure.
The Phase 3 RAINIER trial evaluated povetacicept, an investigational engineered fusion protein designed to inhibit two cytokines involved in immune system activity: B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL). The pre-specified interim analysis at Week 36 demonstrated that the study met its primary endpoint, with povetacicept producing a 52.0% reduction from baseline in proteinuria and a statistically significant 49.8% reduction compared with placebo.
The treatment effect was statistically significant, with a p-value of less than 0.0001. The study also met both secondary endpoints, further supporting the potential of povetacicept as an investigational treatment for adults living with IgAN.
Additional findings showed that the reduction in proteinuria was consistent across demographic, clinical and regional subgroups. Participants in North America experienced a 54.2% reduction in urine protein-to-creatinine ratio (UPCR) compared with placebo. Furthermore, 42.2% of participants receiving povetacicept achieved a 24-hour UPCR below 0.5 g/g, a threshold aligned with current Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, compared with 6.2% of participants receiving placebo.
These results were observed alongside optimized supportive care in both treatment groups. Notably, 65.8% of participants were using sodium-glucose cotransporter-2 (SGLT2) inhibitors, representing one of the highest reported levels of use in a contemporary IgAN clinical trial, according to the company.
Vertex also presented qualitative research examining patient preferences for injectable treatment devices and dosing schedules. The findings indicated that most participants preferred an autoinjector over a prefilled syringe, while a majority favored administration every four weeks rather than weekly injections. In addition, the company announced a new Phase 3b study, the PAVANT IgAN Patient Experience Study, designed to evaluate patient experiences with povetacicept administered through an autoinjector.
Phase 3 RAINIER Trial Demonstrates Significant Proteinuria Reduction
The RAINIER study is evaluating povetacicept in adults with IgAN, with the Week 36 interim analysis providing evidence of its effect on proteinuria, an important marker of kidney damage and disease progression.
Proteinuria occurs when damaged kidney filtering structures allow excessive amounts of protein to pass from the blood into the urine. Persistent proteinuria is associated with an increased risk of declining kidney function and progression toward kidney failure. Reducing proteinuria is therefore a major objective in the management of IgAN.
In the interim analysis, povetacicept achieved a 52.0% reduction in proteinuria from baseline at Week 36. The treatment also demonstrated a 49.8% reduction compared with placebo, with a p-value below 0.0001.
The distinction between these two measurements is important. The 52.0% figure represents the reduction from baseline in the povetacicept treatment group, while the 49.8% figure represents the treatment effect relative to placebo. Together, these findings demonstrate a substantial reduction in proteinuria during the first 36 weeks of treatment.
The study also met both secondary endpoints, although the company’s announcement did not provide additional numerical details for those endpoints.
The findings suggest that povetacicept could offer a potential treatment option for patients with IgAN by targeting biological pathways involved in disease development. Nevertheless, the interim results will need to be considered alongside the full clinical evidence and applicable regulatory assessments.
The publication in NEJM and presentation at ASN Kidney Week provide opportunities for the scientific and medical communities to examine the findings and assess their implications for future IgAN treatment strategies.
Consistent Treatment Effects Across Patient Subgroups
The RAINIER interim analysis showed that the proteinuria reduction was consistent across prespecified demographic, clinical and regional subgroups.
Subgroup analyses are important in clinical development because patients with IgAN can differ in disease severity, baseline clinical characteristics, geographic location and background treatment. Consistency across these groups can help researchers understand whether a treatment effect is broadly observed or concentrated in a particular segment of the study population.
Among participants in North America, povetacicept achieved a 54.2% reduction in UPCR compared with placebo. Vertex described this finding as an unprecedented reduction in the region.
The company also reported that 42.2% of participants receiving povetacicept achieved a 24-hour UPCR below 0.5 g/g at Week 36, compared with only 6.2% in the placebo group.
This threshold is aligned with current KDIGO guidelines and provides an additional way to assess the degree of proteinuria control achieved during treatment.
The difference between the two groups indicates that a greater proportion of participants receiving povetacicept reached this proteinuria level during the reported period. While these results are encouraging, long-term follow-up will be important to establish whether the improvement can be maintained and whether it translates into preservation of kidney function.
The findings were also observed on top of optimized supportive care, making the results relevant to the evaluation of povetacicept as a potential addition to existing disease-management strategies.
High Use of SGLT2 Inhibitors Reflects Contemporary Background Care
One notable feature of the RAINIER study was the use of SGLT2 inhibitors among participants in both treatment arms.
According to Vertex, 65.8% of participants were receiving an SGLT2 inhibitor, representing one of the highest reported rates of use in a contemporary IgAN trial.
SGLT2 inhibitors are medicines that affect glucose and sodium handling in the kidneys. They are also used in certain patients to help protect kidney function and manage chronic kidney disease, depending on the individual’s clinical circumstances and applicable treatment guidance.
Their use as part of background care is relevant because contemporary IgAN trials increasingly evaluate investigational therapies alongside established supportive treatments. This approach can help determine the additional benefit that a new therapy may provide when used in a treatment environment that reflects current clinical practice.
The proteinuria reductions observed in RAINIER were reported on top of optimized supportive care, including the use of SGLT2 inhibitors. This provides important context for interpreting the findings and considering the potential role of povetacicept in future treatment strategies.
However, the study results alone do not establish how povetacicept would compare directly with other approved therapies or whether it would be appropriate for every patient with IgAN. Those questions will require assessment of the complete evidence, treatment guidelines and regulatory decisions.
Vertex Highlights Potential for Convenient At-Home Administration
Carmen Bozic, M.D., executive vice president of Global Medicines Development and Medical Affairs and chief medical officer at Vertex, highlighted the efficacy findings, safety profile and proposed administration schedule of povetacicept.
Bozic said the results at 36 weeks demonstrated substantial treatment activity and emphasized the potential convenience of administration at home every four weeks using a low-volume autoinjector.
She also acknowledged the contributions of patients, investigators and study teams involved in RAINIER. According to the company, the study became the largest and fastest-enrolling contemporary IgAN trial to date.
Vertex is continuing to advance the program as it approaches the November 30 prescription drug user fee act (PDUFA) target action date referenced in the announcement.
The dosing approach could be relevant for patients managing a chronic condition that requires ongoing monitoring and treatment. At-home administration may reduce the need for repeated visits solely for injections, although the practical arrangements would depend on the final product instructions, regulatory authorization and individual patient circumstances.
Povetacicept is designed to be administered every four weeks through a low-volume autoinjector. This approach combines a relatively infrequent dosing schedule with a device intended to support self-administration.
The potential convenience of this delivery method is being examined through additional patient-experience research, which aims to understand how adults with IgAN perceive different injectable treatment options.
Dual BAFF and APRIL Inhibition Targets Upstream Disease Mechanisms
Povetacicept is an engineered fusion protein designed to inhibit BAFF and APRIL simultaneously. Both cytokines play roles in B-cell biology and antibody production, processes relevant to the development of IgAN.
In IgAN, abnormal immune activity can contribute to the production of immunoglobulin A-containing immune complexes. These complexes can accumulate in the kidney’s glomeruli, trigger inflammation and contribute to progressive tissue damage.
BAFF and APRIL are involved in pathways that regulate B cells and antibody-producing cells. By inhibiting both cytokines, povetacicept is designed to influence upstream mechanisms associated with pathogenic immune complex production.
Richard Lafayette, M.D., professor of medicine in nephrology at Stanford University Medical Center and RAINIER Steering Committee co-chair, presented the trial data at ASN Kidney Week.
Lafayette emphasized the importance of the findings as clinical evidence supporting simultaneous BAFF and APRIL inhibition in IgAN. He also highlighted the design of povetacicept as a high-potency, high-affinity TACI fusion protein intended to provide broad tissue distribution and dual cytokine inhibition.
According to Lafayette, the results were among the most compelling he had seen in IgAN and highlighted the therapy’s potential to become an important new option for patients with this chronic progressive disease.
The findings provide further support for continued investigation of this therapeutic strategy. However, additional evidence will be needed to determine the durability of proteinuria reduction, the effect on long-term kidney function and the therapy’s overall benefit-risk profile.
Patient Study Shows Preference for Autoinjectors
In addition to the RAINIER efficacy findings, Vertex presented a qualitative study examining patient perspectives on injectable therapies for IgAN.
The study, titled Patient Perceptions of Injectable Therapies Among Adults with IgAN: A Qualitative Study (abstract #TH-PO0473), included in-depth, one-on-one interviews with 25 adults living with IgAN in the United States.
Participants were shown pictures and short videos of different injection devices and asked to assess characteristics related to treatment administration. The research focused on understanding preferences that could affect the acceptability and practicality of injectable therapies.
The findings showed that 96% of participants, or 24 of the 25 adults interviewed, preferred the characteristics of an autoinjector over those of a prefilled syringe.
Participants cited features such as the needle not being visible and the elimination of manual needle insertion as reasons for their preferences.
These characteristics may be important for people who are uncomfortable with needles or prefer a simpler injection process. An autoinjector can be designed to automate aspects of administration, potentially reducing the steps patients must perform themselves.
The study also found that 80% of participants, or 20 of the 25 adults interviewed, preferred dosing every four weeks over weekly administration.
Convenience and the ability to travel or spend time away from home were among the leading reasons for preferring the less frequent dosing schedule.
Although the study provides useful insights into patient preferences, its small sample size means the results should not automatically be generalized to all adults with IgAN. Individual preferences may vary, and treatment decisions will continue to depend on clinical factors, safety, efficacy and patient needs.
Nevertheless, the findings support the importance of considering administration methods and dosing frequency when developing treatments for chronic diseases.
New PAVANT IgAN Patient Experience Study Announced
Vertex has also announced the PAVANT IgAN Patient Experience Study (NCT07890909), a Phase 3b, open-label, single-arm study evaluating povetacicept injection administered through an autoinjector in adults with IgAN.
The new study is intended to investigate patient experience with the injection device and administration approach. It complements the company’s qualitative research into preferences for injectable treatment options.
As an open-label, single-arm study, PAVANT is designed differently from a placebo-controlled efficacy trial. Its focus on patient experience can provide additional information about how participants interact with the delivery device and how the administration approach fits into their lives.
The research is particularly relevant given the preference for autoinjectors and four-week dosing reported in the 25-person qualitative study.
Further details about Vertex’s presence at ASN Kidney Week 2026 and its IgAN program are available through the company’s kidney congress website at news.vrtx.com/kidney-congress.
Investor Event to Address Kidney Disease Pipeline
Vertex also scheduled an investor event and webcast for October 23, from 6:15 p.m. to 7:00 p.m. Mountain Daylight Time (MDT), corresponding to 8:15 p.m. to 9:00 p.m. Eastern Daylight Time (EDT), in Denver, Colorado.
The event is intended to discuss the povetacicept data in IgAN, the company’s program in APOL1-mediated kidney disease (AMKD), and other developments across its kidney disease portfolio.
The presentation and question-and-answer session were scheduled to be accessible through the Investor Relations section of Vertex’s website at investors.vrtx.com. The company recommended that participants register at least 15 minutes before the scheduled webcast to ensure a timely connection. An archived version was also planned to be made available on the company’s website.
The event provides an opportunity for investors to review the latest clinical findings and learn more about Vertex’s broader strategy in kidney disease.
Next Steps for Povetacicept Development
The publication of the RAINIER findings in NEJM, their presentation at ASN Kidney Week 2026 and the initiation of the PAVANT patient-experience study represent important developments in Vertex’s povetacicept program.
The Phase 3 interim analysis demonstrated a 52.0% reduction in proteinuria from baseline and a statistically significant 49.8% reduction relative to placebo at Week 36. The findings also showed consistent treatment effects across prespecified subgroups and a greater proportion of patients achieving a UPCR below 0.5 g/g.
The reported results, together with the use of optimized supportive care and the favorable patient preferences for autoinjector administration, support continued evaluation of povetacicept as a potential treatment for IgAN.
The company’s focus now includes advancing the clinical program, assessing patient experience with the injection device and progressing through the applicable regulatory process. The November 30 PDUFA target action date cited by Vertex represents an important upcoming milestone.
Ultimately, further clinical and regulatory assessment will determine whether povetacicept can provide a new treatment option for adults with IgAN. Longer-term evidence on kidney function, safety and durability of response will remain essential to understanding its potential role in managing this progressive kidney disease.
About RAINIER
RAINIER (NCT06564142) is a global Phase 3 randomized, double-blind, placebo-controlled pivotal trial of povetacicept 80 mg administered subcutaneously every 4 weeks versus placebo on top of standard of care in 605 adults with IgAN (N=557 in main cohort, N=48 in the exploratory cohort).
The trial was designed to have a pre-planned interim analysis evaluating the percent change from baseline in UPCR for the povetacicept arm versus placebo after a pre-specified number of patients reach 36 weeks of treatment. Final analysis will occur at two years of treatment, with a primary endpoint of total estimated glomerular filtration rate (eGFR) slope through Week 104. RAINIER is the largest trial conducted in IgAN and achieved full enrollment faster than any contemporary IgAN trial.
As previously reported, patients treated with povetacicept achieved a 52.0% reduction from baseline in 24-hour UPCR at Week 36, with a statistically significant and clinically meaningful reduction of 49.8% in 24-hour UPCR compared to placebo (P<0.0001).
The trial also met its secondary objective. For the first secondary endpoint, patients treated with povetacicept demonstrated a 77.4% reduction from baseline in serum galactose deficient IgA1 (Gd-IgA1) compared to an increase of +9.1% in the placebo group, yielding a reduction of 79.3% compared to placebo (P<0.0001). For the second secondary endpoint, in patients with baseline hematuria, 85.1% achieved hematuria resolution in the povetacicept treatment group compared to 23.4% in the placebo group, resulting in hematuria resolution of 61.7% compared to placebo (P<0.0001).
Povetacicept was generally safe and well tolerated. The majority of adverse events (AEs) were mild to moderate. The most common events (≥10% of participants in either treatment group) for the povetacicept group versus the placebo group were upper respiratory tract infection (18.3% vs 11.4%), nasopharyngitis (9.7% vs 12.4%), and injection site reactions (14.5% vs 2.2%). There were no serious adverse events (SAEs) related to povetacicept and no deaths in the trial. There were no opportunistic infections, and no discontinuations due to infections. As expected, anti-drug antibodies (ADAs) were observed; these ADAs had no impact on efficacy or the risk profile.
Results from the RAINIER trial support the Biologics License Application (BLA) for povetacicept, which has been accepted by the U.S. Food and Drug Administration (FDA) for accelerated approval in adults with IgAN. The Prescription Drug User Fee Act (PDUFA) target action date is November 30, 2026.
The RAINIER trial continues in a blinded manner until the last patient enrolled completes 104 weeks. Patients in RAINIER who have completed the Week 104 visit are eligible to enroll in the open-label extension study (NCT07807995), “A Phase 3 Open-Label Study of Long-term Treatment With Povetacicept in Adults With Immunoglobulin A Nephropathy,” and receive an additional 104 weeks of treatment and follow-up.
About Povetacicept
Povetacicept is a dual inhibitor of the BAFF and APRIL cytokines, which promote B cell activation, differentiation and/or survival, and provides B cell control by inhibiting the ability of BAFF and APRIL to drive the pathogenesis of multiple immune-mediated diseases. Due to its engineered TACI domain, povetacicept has demonstrated improved binding affinity, potency, pharmacokinetics, and/or tissue distribution compared to other APRIL, BAFF, and dual BAFF+APRIL inhibitors in preclinical studies.
If povetacicept is approved by the FDA, Vertex plans to launch povetacicept as a low-volume (<0.5 mL) subcutaneous autoinjector delivered once every 4 weeks via at-home administration.
IgAN is the first of multiple indications that Vertex is exploring for povetacicept given its pipeline-in-a-product potential. There are ongoing studies including the Phase 2/3 OLYMPUS trial (NCT07204275) in primary membranous nephropathy (pMN) and the Phase 2 ETNA trial (NCT07501702) in generalized myasthenia gravis (gMG).
About IgA Nephropathy (IgAN)
IgAN is a serious, progressive, life-threatening kidney disease driven by uncontrolled autoreactive B cell activity and is the most common cause of primary glomerulonephritis, affecting approximately 330,000 people in the United States and Europe and more than 1.5 million globally. IgAN results from the deposition of circulating immune complexes, consisting of immunoglobulins and galactose-deficient immunoglobulin A (Gd-IgA1), in the renal glomerular mesangium, triggering kidney injury and fibrosis.
About Vertex
Vertex is a global biotechnology company that invests in scientific innovation to create transformative medicines for people with serious diseases and conditions. The company has approved therapies for cystic fibrosis, sickle cell disease, transfusion-dependent beta thalassemia, acute pain and acromegaly, and it continues to advance clinical and research programs in these areas.
Vertex also has a robust clinical pipeline of investigational therapies across a range of modalities in other serious diseases where it has deep insight into causal human biology, including IgA nephropathy, neuropathic pain, APOL1-mediated kidney disease, primary membranous nephropathy, congenital adrenal hyperplasia, adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome, autosomal dominant polycystic kidney disease, type 1 diabetes, generalized myasthenia gravis, and myotonic dystrophy type 1.
Vertex was founded in 1989 and has its global headquarters in Boston, with international headquarters in London. Additionally, the company has research and development sites and commercial offices in North America, Europe, Australia, Latin America and the Middle East. Vertex is consistently recognized as one of the industry’s top places to work, including 17 consecutive years on Science magazine’s Top Employers list and one of Fortune’s 100 Best Companies to Work For.