Inozyme Pharma presents positive interim data on INZ-701 at CHOP Cardiology 2025

Inozyme Pharma Inc. (Nasdaq: INZY), a clinical-stage biopharmaceutical company focused on developing treatments for rare diseases affecting bone health and blood vessels, has presented promising new data on its lead candidate, INZ-701, at the CHOP Cardiology Annual Meeting 2025 in Orlando, Florida. The findings, derived from the company’s Expanded Access Program (EAP) and its ongoing clinical trials, offer fresh hope for infants and young children diagnosed with ENPP1 Deficiency, a devastating condition with no approved therapies.

The latest data highlights INZ-701’s potential to improve survival rates, stabilize arterial calcification, and enhance overall health outcomes in young patients. The presentation, led by Kurt Gunter, M.D., Senior Vice President and Chief Medical Officer at Inozyme Pharma, builds upon earlier clinical evidence and regulatory momentum.

What is ENPP1 Deficiency, and why is it a critical health concern?

ENPP1 Deficiency is a rare and severe genetic disorder that disrupts the PPi-Adenosine Pathway, a crucial mechanism regulating bone and vascular health. The condition leads to excessive mineralization in soft tissues and arteries, causing complications such as generalized arterial calcification of infancy (GACI Type 1), which is often fatal within the first six months of life. As patients grow older, they may develop autosomal recessive hypophosphatemic rickets type 2 (ARHR2), a condition that results in painful bone softening, mobility challenges, and an increased risk of fractures. In some cases, adolescents and adults experience osteomalacia, a disorder marked by weakened bones and chronic pain.

ENPP1 Deficiency is estimated to affect approximately 1 in 64,000 pregnancies worldwide, although recent research suggests that undiagnosed ENPP1 Deficiency may be more common than previously believed. Many individuals carrying only one mutated copy of the gene exhibit severe symptoms, further emphasizing the need for effective treatments. Despite the growing understanding of this condition, there are currently no approved therapies available, leaving patients and families with limited treatment options.

What do the latest clinical trial results reveal about INZ-701?

The latest data from Inozyme Pharma’s clinical studies stem from both the ENERGY 1 trial and the Expanded Access Program (EAP), which evaluated INZ-701 in infants and young children diagnosed with GACI Type 1. The study involved six patients—three infants in the ENERGY 1 trial and three additional patients (two infants and a 2.5-year-old child) in the EAP—who received INZ-701 for treatment durations ranging from three weeks to 22 months.

Findings from the study reinforce the potential of enzyme replacement therapy (ERT) with INZ-701 to correct metabolic imbalances associated with ENPP1 Deficiency. The data indicate that infants treated with INZ-701 experienced higher survival rates compared to historical controls. The survival rate among treated patients exceeded 80%, a significant improvement over the 50% survival rate typically observed in untreated infants.

Arterial calcification, a hallmark of GACI Type 1, showed notable reductions in several patients, with some demonstrating complete resolution of vascular calcifications. The stabilization or improvement of left ventricular ejection fraction (LVEF) suggested a positive impact on cardiac function. Additionally, there was no radiographic evidence of rickets in patients evaluated beyond one year of age, supported by increased serum phosphate levels.

The safety profile of INZ-701 remains encouraging, with no reports of serious treatment-related adverse events. Minor injection site reactions were observed in some cases, while transient anti-drug antibody (ADA) responses were noted but did not impact treatment efficacy or pharmacokinetics in most patients.

What progress has Inozyme Pharma made with the ENERGY 3 pivotal trial?

Building on the promising results of its early-stage trials, Inozyme Pharma has successfully completed patient enrollment for its ENERGY 3 pivotal trial, a study designed to further evaluate the safety and efficacy of INZ-701 in pediatric patients aged 1 to 12 years. The trial aims to measure key clinical outcomes, with rickets progression being a primary focus.

Regulatory agencies, including the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA), have guided the study design, emphasizing plasma PPi levels as a key biomarker. In Europe, the study incorporates radiographic global impression of change (RGI-C) as a co-primary endpoint to assess improvements in bone health.

With 25 patients enrolled, the study’s 2:1 randomized design provides significant statistical power to detect meaningful treatment effects. Strong patient interest in the trial has led to additional screenings, and Inozyme Pharma anticipates completing the one-year dosing period for all participants by January 2026. The company expects topline data from the ENERGY 3 trial to be available in early 2026.

What are Inozyme Pharma’s next steps in targeting ABCC6 Deficiency?

In addition to advancing research on ENPP1 Deficiency, Inozyme Pharma is making progress in the development of INZ-701 for ABCC6 Deficiency, a genetic disorder associated with vascular and retinal calcification, cardiovascular complications, and an increased risk of early mortality.

The company previously reported promising data from an open-label, dose-escalation study in adults, which demonstrated positive improvements in vascular calcification and retinal pathology after 48 weeks of treatment. The findings support further clinical research, particularly in pediatric patients affected by early-onset forms of the disease.

To address the unmet medical need in children with ABCC6 Deficiency, Inozyme Pharma is planning the ASPIRE pivotal trial, which will evaluate INZ-701’s impact on major adverse clinical events over a two-year treatment period. The study is expected to enroll approximately 70 patients under 18 years old, including those with both biallelic and monoallelic ABCC6 mutations.

Regulatory agencies in the U.S. and Europe have provided preliminary support for the ASPIRE trial, and Inozyme Pharma is working to finalize the study design. The company expects to initiate the trial in early 2026, pending ongoing regulatory review and financial resources.

What does Inozyme Pharma’s research mean for rare disease treatment?

Inozyme Pharma’s advancements in targeting the PPi-Adenosine Pathway represent a significant step forward in the treatment of rare genetic diseases affecting mineralization and vascular health. By developing enzyme replacement therapy (ERT) solutions like INZ-701, the company aims to provide effective treatment options where none currently exist.

With regulatory momentum building and pivotal trials advancing, Inozyme Pharma is positioned to make a meaningful impact in the rare disease community. The company’s commitment to scientific innovation and patient advocacy underscores its mission to address life-threatening disorders with high unmet medical needs.