MBX Biosciences closes on $115M in drug-development funding

INDIANAPOLIS – Less than one month after initiating a multiple ascending dose study for its lead clinical asset, MBX Biosciences secured $115 million in Series B financing to advance its pipeline of Precision Endocrine Peptides for endocrine disorders.

The funds, coupled with earlier Series A financing, provide the Indiana-based company with about $150 million in total funding that will support its clinical asset and other developmental programs, Kent Hawryluk, MBX’s CEO, told BioSpace.

The company’s lead asset, MBX 2109, first entered the clinic in December for the treatment of hypoparathyroidism. It successfully completed the single ascending dose portion of the trial. 

In October, MBX Biosciences initiated the multiple ascending dose portion of the Phase I study. In this portion of the study, participating subjects receive either MBX 2109 or a placebo once weekly for four weeks. The primary outcome measures will evaluate safety and tolerability. Secondary outcome measures will evaluate pharmacokinetics and pharmacodynamics.

MBX 2109 is an investigational long-acting parathyroid hormone peptide prodrug in development as a PTH replacement therapy. The goal of this experimental drug is not only to provide greater efficacy than standard-of-care treatments but also to simplify a patient’s disease management. MBX 2109 was awarded Orphan Drug designation in July.

Hawryluk said the Phase I program evaluates the drug for weekly dosing in healthy volunteers before a potential Phase II trial in patients diagnosed with hypoparathyroidism, which affects roughly 200,000 people worldwide. 

Unlike other diseases where endocrine replacement is the standard of care, patients with hypoparathyroidism are treated with high doses of calcium and vitamin D supplements. And that can lead to some serious problems in the future, Hawryluk said. 

“When you give large doses of calcium, you overshoot the mark. This can result in the calcification of organs and also kidney stones. This is a real problem.”

Hawryluk noted that the current treatment regimen for this disease does not address the underlying pathophysiology, which is to restore the missing hormone.

MBX Biosciences’ approach, with its Precision Endocrine Peptides, differs from traditional peptide therapeutics. He said that conventional therapeutics tend to rapidly degrade in circulation and require repeated dosing. 

The MBX therapeutics, which are based on technology from peptide pioneer Richard DiMarchi and his University of Indiana lab, are long-acting prodrugs that require once-per-week dosing. 

Looking Ahead

The ongoing Phase I study is expected to be completed in 2023. If all goes as expected, a Phase II trial in patients with hypoparathyroidism could begin in the second half of next year.

Although hypoparathyroidism is a rare disease, Hawryluk said there is such an unmet need in this patient population that his team does not anticipate any issues recruiting patients for clinical trials. He said they expect “great reception” from the patient community. 

Wellington Management led the Series B financing. Supporters include RA Capital Management and Norwest Venture Partners. Existing investors, including Frazier Life Sciences, New Enterprise Associates and OrbiMed, also participated in the Series B. The funds from this raise will support MBX through 2025. 

Beyond the lead 2109 asset, MBX Biosciences has a preclinical program in development dubbed MBX 1416 as a potential treatment for post-bariatric hypoglycemia. Hawryluk anticipates activities supporting the filing of an Investigational New Drug application to be completed next year, with the initiation of a Phase I trial following shortly after that. 

Funds from the Series B are also expected to be used to expand MBX Biosciences’ pipeline. Hawryluk said the company has several developmental candidates that it will nominate for advancement. As the number of assets in development grows, so too will the number of employees. MBX currently employs 19 full-time staff members and is looking to expand its headcount to support its clinical development plans and goals.

“Our vision is to build a fully-integrated biopharmaceutical company,” he said.