Obesity drug development has entered a new era led by the rapid rise of GLP-1-based therapies.
But as these medicines become more widely used, increasing clinical questions are coming to the forefront, which include how to preserve muscle during weight loss, improve tolerability, maintain weight loss over time and address obesity-related cardiometabolic complications.
The scale of the unmet need remains substantial. In 2022, 2.5 billion adults worldwide were overweight, including more than 890 million adults living with obesity, according to the World Health Organization (WHO). Worldwide adult obesity has more than doubled since 1990, while adolescent obesity has quadrupled.
At the same time, obesity is closely linked with cardiometabolic diseases, including type 2 diabetes, cardiovascular disease and heart failure, raising the need for therapies that go beyond weight reduction alone.
CEO and Chief Scientific Officer
iBio
Xtalks spoke with Martin Brenner, DVM, PhD, CEO and Chief Scientific Officer of iBio, about the next-gen obesity drug space, including the company’s first-in-human plans for one of its lead candidates in Australia and the global clinical development considerations shaping early-stage obesity and cardiometabolic trials.
San Diego-based iBIO is developing antibody-based therapies for obesity, cardiometabolic disease and cardiopulmonary conditions, with a focus on what the company describes as next-generation approaches that could complement GLP-1 therapies.
Looking Beyond the First Wave of GLP-1s
GLP-1 receptor agonists have reshaped obesity treatment by demonstrating clinically meaningful weight loss and broader metabolic benefits. But Brenner said iBio’s strategy is built around the idea that GLP-1s are not the end point of obesity drug development.
“We’re a company that early on realized that GLP-1 drugs will become standard of care and cornerstones of obesity treatment,” Brenner said. “And we’ve looked beyond those initial molecules.”
For iBio, that means asking what gaps remain after a patient receives a GLP-1 therapy. According to Brenner, those gaps include muscle loss during weight reduction, gastrointestinal adverse effects such as nausea and vomiting, long-term durability of weight loss and obesity-related cardiovascular complications.
The company’s obesity and cardiometabolic pipeline includes IBIO-600, a long-acting anti-myostatin antibody designed to preserve lean mass and improve body composition; IBIO-610, an Activin E antibody being developed for obesity and cardiometabolic disease; an amylin antibody program; and a bispecific antibody program targeting pathways relevant to obesity and heart failure with preserved ejection fraction (HFpEF).
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Why Muscle Preservation Is Emerging as a Key Obesity Treatment Goal
One of the most important unresolved issues in obesity treatment is the quality of weight loss. Weight reduction can involve loss of both fat mass and lean mass, and preserving muscle may be especially important for older adults and patients at risk of frailty.
“The main culprit in causing disease and obesity is not the weight itself; it’s actually the visceral fat,” Brenner said. “Muscle is a healthy tissue. The more muscle you have, the more mitochondria you have, which is linked to longevity and health.”
IBIO-600 is a long-acting monoclonal antibody targeting myostatin and GDF11, which are negative regulators of skeletal muscle growth. iBio is developing the therapy to preserve lean mass and improve body composition in obesity, including as a potential adjunct to GLP-1-based therapies.
In April 2026, iBio announced that IBIO-600 had received Clinical Trial Notification acknowledgement from Australia’s Therapeutic Goods Administration and ethics approval from a human research ethics committee, enabling the start of a first-in-human Phase I trial in Australia. The randomized, double-blind, placebo-controlled, single ascending dose study will evaluate safety, tolerability, pharmacokinetics and pharmacodynamics in overweight and obese adults.
Preclinical non-human primate data previously showed an extended half-life of 40 to 52 days after a single administration, along with dose-dependent increases in lean mass of up to 5.1% and reductions in fat mass. The company has said IBIO-600 is engineered for infrequent dosing, with potential administration two to four times per year.
Brenner said the goal is not simply to help patients lose weight, but to help them lose weight in a healthier way.
“What we aim for with our myostatin approach is that, as patients lose body weight, they retain muscle mass, which ultimately should retain bone strength,” he explained.
Addressing Durability and Tolerability
Muscle preservation is only one part of iBio’s broader strategy. Brenner also pointed to weight maintenance and tolerability as major next-generation obesity treatment needs.
Many patients regain weight after stopping anti-obesity medications. In the STEP 1 trial extension, participants who discontinued semaglutide regained two-thirds of their prior weight loss within one year after treatment withdrawal, while cardiometabolic improvements also shifted back toward baseline.
Brenner said iBio is looking at durability through its Activin E program. iBio’s IBIO-610 is designed to block Activin E and is engineered for extended half-life, with the company describing potential dosing two to four times per year. Human genetic studies have linked loss-of-function variants in INHBE, the gene encoding Activin E, with reduced visceral adiposity and improved lipid profiles.
In March 2026, iBio reported preclinical body composition data for IBIO-610 in obese non-human primates, including reductions in visceral and total fat mass in a small, not statistically powered study.
The company’s amylin antibody program is aimed at tolerability. Current obesity therapies can be limited by gastrointestinal side effects, and iBio says its amylin approach is intended to provide long-acting, controlled pharmacology that could offer improved tolerability and infrequent dosing.
Expanding Into Cardiometabolic and Cardiopulmonary Disease
iBio is also looking beyond obesity into related cardiometabolic and cardiopulmonary complications. Brenner highlighted HFpEF as a major area of need, particularly in patients with obesity and cardiometabolic disease.
HFpEF accounts for a substantial share of heart failure cases and remains difficult to treat. The American College of Cardiology noted in 2025 that while several pharmacologic advances have emerged in recent years, unmet clinical need remains in HFpEF care. Pulmonary hypertension associated with HFpEF is also considered a high-risk condition with limited treatment options. An American Heart Association scientific advisory described PH-HFpEF as a growing epidemic with high morbidity and mortality.
iBio has expanded into pulmonary hypertension associated with HFpEF with a selective bispecific antibody designed to block Activin A, GDF8/myostatin and GDF11. The company says the program is intended to reduce cardiac fibrosis, reverse pulmonary vascular remodeling and improve whole-body functional capacity, while avoiding safety issues associated with broader TGF-beta ligand blockade.
Brenner said the company’s work in cardiometabolic disease led it to focus on components of the TGF-beta pathway that could potentially address HFpEF symptoms and disease progression.
Why iBio Chose Australia for Its First-in-Human Study
iBio selected Australia for its first-in-human IBIO-600 study, a decision Brenner said reflects the global nature of biotech development.
“Biotech, as we all know, is a global play,” Brenner said. “This is not something that you can execute on a local level. It’s impossible.”
For iBio, the goal is to move efficiently toward human proof-of-concept data. Brenner said Australia offers a strong early-phase clinical trial infrastructure, a smoother regulatory and operational pathway and established logistics for receiving GMP material manufactured in China.
He emphasized that the decision is not about lower safety standards by any means.
“It is not by far that Australia has lower mandates on patient safety. That is absolutely not the case,” Brenner said. “It’s the same safety, and patient safety is our number one driver. However, it’s a much more smoother and faster process to get from submission to ultimately being able to dose the first patient.”
According to iBio, first participant dosing in the IBIO-600 Phase I trial is expected in the second quarter of 2026. Brenner said the company expects interim Phase I data by the end of the year, with its Activin E program expected to be filed in Australia later in 2026 and first dosing anticipated in early 2027.
Infrastructure, Imaging and the Right Patient Population
For early-phase obesity and cardiometabolic trials, Brenner said one of the most important considerations is access to the right patient population.
In obesity, recruitment may be more feasible than in some rare diseases because of high prevalence, but the principle remains the same in that trial sites must be able to enroll patients who match the study’s scientific and regulatory needs.
Clinical infrastructure is also critical. Brenner pointed to ethics committee processes, CRO capabilities, imaging access and body composition tools as important parts of the site selection equation.
The company does a good amount of imaging with DEXA scans or MRIs for body composition, he explained.
For a therapy like IBIO-600, which is being developed to preserve lean mass and improve body composition, these tools are central to measuring whether the drug is doing what it is designed to do.
Brenner also noted that small companies cannot build these systems from scratch in every region. They need to work within established clinical trial ecosystems, with advisors, CRO partners and investigators who understand the country-specific process.
Early-Stage Data Must Support Later Global Trials
Although Australia is an attractive starting point, Brenner said iBio is already thinking about the larger development path. Early clinical data must be useful for later-stage studies, which means population diversity and generalizability matter even in early trials.
“We’re looking at the whole trajectory, but we’re cutting it up a little bit,” he said.
Australia offers a diverse patient population and a strong early-stage clinical trial environment, Brenner said, but it is not large enough to support massive Phase III programs on its own. Later-stage obesity and cardiometabolic trials would likely need to expand into multiple regions, including the US, Canada and Europe.
This is especially important because obesity and type 2 diabetes can differ across populations. Brenner noted that these diseases may present differently in Southeast Asian populations compared with Caucasian populations, making diversity important for dose selection, dosing frequency and early signals of efficacy.
“You do not want to repeat a Phase II study because you do not have the diversity enrolled into your clinical trial,” he said.
San Diego, Talent and the Broader Biotech Ecosystem
Brenner also spoke about iBio’s decision to locate in San Diego. He described the region as a biotech ecosystem that supports entrepreneurial scientists, repeat founders and a diverse talent base.
“Biotech thrives on diversity, not just from a patient population, but also from an employee and people standpoint,” he said.
For emerging biotech companies, location can influence not only access to investors and partners, but also the ability to attract experienced scientific and executive talent. Brenner said this is becoming an increasingly important consideration as companies plan globally and build contingency strategies across regulatory regions.
“You can only execute your plans if you have the right people working in the company,” he said.
A Broader View of Obesity Drug Development
The first wave of GLP-1 therapies has changed expectations for obesity treatment. But the next wave may be defined by a broader set of treatment goals that include preserving muscle, reducing visceral fat, improving durability, minimizing side effects and addressing obesity-related cardiovascular disease.
For iBio, that means building a pipeline around second-generation obesity and cardiometabolic therapies that could complement existing drugs rather than simply compete with them.
It also means thinking globally from the start. From manufacturing in China to early clinical execution in Australia and future trial expansion across North America and Europe, iBio’s strategy reflects how modern biotech development increasingly depends on cross-border infrastructure, patient diversity and operational speed.
As obesity treatment becomes more sophisticated, the field may move beyond a narrow focus on weight loss alone. The next challenge will be defining what healthier, more durable and more cardiometabolically meaningful weight loss looks like, and how to test those therapies efficiently in the patients who need them most.
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