PASADENA, Calif.--(BUSINESS WIRE)-- Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) today announced presentation of preclinical data supporting the advancement of two first-in-class clinical stage, RNAi-based investigational therapeutics being developed for the treatment of obesity and metabolic diseases. The two candidates, ARO-INHBE and ARO-ALK7, have the potential to reduce body weight and fat mass with a novel mechanism of action that may lead to improved preservation of lean muscle mass compared to currently approved obesity therapies. The presentation titled, “Targeting Obesity with RNAi-based Therapies,” was included in the Oligo-Based Therapeutics: Clinical Advancements session at the RNA Leaders Europe Congress 2025 held March 4–6, 2025 in Basel, Switzerland.

“Arrowhead is leading the field in the discovery and development of potential new RNAi-based therapies for obesity and metabolic diseases. Our first two programs, ARO-INHBE and ARO-ALK7, both seek to intervene in a known biological pathway with strong support from human genetics studies and compelling preclinical results in mouse models of obesity where INHBE silencing in the liver and ALK7 silencing in adipose tissue led to dramatic reductions in fat mass without reductions in lean mass.” said James Hamilton, M.D., MBA, Chief Medical Officer and Head of R&D. “We now move on to Phase 1/2 clinical studies in patients with obesity that are designed to evaluate single- and multiple-ascending doses of ARO-INHBE and ARO-ALK7 as monotherapy, as well as multiple-ascending doses in combination with tirzepatide, a GLP-1/GIP receptor co-agonist.”

Select ARO-INHBE Preclinical Results:

In a diet-induced obese (DIO) mouse model, hepatic INHBE silencing with siRNA led to a 19% suppression in body weight gain relative to vehicle controls. Treated mice exhibited improved body composition with a 22% reduction of fat mass while preserving lean mass. Treated mice also demonstrated a trend to improved glycemic control. Hepatic INHBE silencing in DIO mice enhanced catecholamine sensitivity, increasing lipid mobilization and oxidation, which was not associated with liver steatosis. In fact, treated animals showed less liver fat accumulation relative to saline controls.

Select ARO-ALK7 Preclinical Results:

DIO mice treated with an ALK7 siRNA exhibit a 39% suppression in body weight gain relative to controls. Adipose ALK7 silencing reduced fat mass by 50% while preserving lean mass. Similar to INHBE silencing in hepatocytes, ALK7 silencing in adipocytes enhanced catecholamine sensitivity, increasing lipid mobilization and oxidation, which was not associated with liver steatosis. In fact, treated animals showed less liver fat accumulation relative to saline controls. In combination studies with tirzepatide, ALK7 siRNA enhanced the therapeutic benefits versus tirzepatide monotherapy, with additive effects on body weight and fat mass reduction while ameliorating the significant loss of lean mass associated with tirzepatide monotherapy.

Arrowhead believes it is the first company to initiate clinical studies against these two novel targets, INHBE and ALK7. INHBE, and the ligand it encodes Activin E, signals the ALK7 receptor on adipose tissue to store fat and suppress lipolysis. Intervening in this known biological pathway has the potential to improve adipose dysfunction in obesity by increasing lipolysis and reducing adipose hypertrophy and visceral adiposity. In addition, published human genetics studies suggest that loss-of-function variants of INHBE and/or ALK7 are associated with reduced abdominal fat and lower risk of coronary heart disease and type 2 diabetes.

Arrowhead is currently conducting Phase 1/2 clinical studies of ARO-INHBE and ARO-ALK7. Dosing in the ARO-INHBE study was initiated in December 2024 with initial data possible by year end 2025. The company anticipates dosing in the ARO-ALK7 study will begin in the second quarter of 2025 with initial data from the single-ascending dose portion of the study possible by year end 2025.

The presentation may be accessed on the Events and Presentations page in the Investors section of the Arrowhead website.

About ARO-INHBE

ARO-INHBE is designed to reduce the hepatic expression of the INHBE gene and its secreted gene product, Activin E. INHBE is a promising genetically validated target in which loss-of-function INHBE variants in humans are associated with improved fat distribution and lower risk of metabolic diseases, such as type 2 diabetes. Activin E acts as a ligand in a pathway that regulates energy homeostasis in adipose tissue. Inhibiting this pathway with investigational ARO-INHBE treatment has the potential to increase lipolysis, and reduce adipose hypertrophy and dysfunction, visceral adiposity, and insulin resistance.

About the AROINHBE-1001 Phase 1/2 Study

AROINHBE-1001 (NCT06700538) is a Phase 1/2a dose-escalating study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ARO-INHBE in up to 78 adult volunteers with obesity. Part 1 of the study is designed to assess single and multiple doses of ARO-INHBE monotherapy, and Part 2 of the study is designed to assess ARO-INHBE in combination with tirzepatide, a subcutaneously administered GLP-1/GIP receptor co-agonist that has been approved in the United States and the European Union for management of type 2 diabetes mellitus since 2022 and weight management since 2023/2024 respectively.

About ARO-ALK7

ARO-ALK7 is designed to silence adipocyte expression of the ACVR1C gene to reduce the production of Activin receptor-like kinase 7 (ALK7), which acts as a receptor in a pathway that regulates energy homeostasis in adipose tissue. In large genetic datasets, reduced ACVR1C expression has been associated with healthier adipose distribution and reduced risk of obesity-related metabolic complications. Treatment with investigational ARO-ALK7 has the potential to reduce visceral adiposity and improve lipid and glycemic parameters.

About the AROALK7-1001 Phase 1/2a Study

AROALK7-1001 is a Phase 1/2a first-in-human dose-escalating study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ARO-ALK7 in up to 90 adult volunteers with obesity. Part 1 of the study is designed to assess single and multiple doses of ARO-ALK7 monotherapy, and Part 2 of the study is designed to assess ARO-ALK7 in combination with tirzepatide, a subcutaneously administered GLP-1/GIP receptor co-agonist that has been approved in the United States and the European Union for management type 2 diabetes mellitus since 2022 and weight management since 2023/2024 respectively.

About Arrowhead Pharmaceuticals

Arrowhead Pharmaceuticals develops medicines that treat intractable diseases by silencing the genes that cause them. Using a broad portfolio of RNA chemistries and efficient modes of delivery, Arrowhead therapies trigger the RNA interference mechanism to induce rapid, deep, and durable knockdown of target genes. RNA interference, or RNAi, is a mechanism present in living cells that inhibits the expression of a specific gene, thereby affecting the production of a specific protein. Arrowhead’s RNAi-based therapeutics leverage this natural pathway of gene silencing.

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Source: Arrowhead Pharmaceuticals, Inc.

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