Ambros Fortifies Neridronate Patent, Fueling Hope for CRPS-1 Patients

IRVINE, CA – March 31, 2026 – For the thousands of Americans living with the excruciating, life-altering pain of Complex Regional Pain Syndrome Type 1 (CRPS-1), the therapeutic landscape has long been a barren desert with no FDA-approved treatments. Today, a significant development offers a new oasis of hope. Ambros Therapeutics, Inc. announced it has received a Notice of Allowance from the United States Patent and Trademark Office (USPTO) for a new patent application related to its lead investigational drug, neridronate.

This allowance is a crucial step that not only strengthens the company's intellectual property but also extends the potential market exclusivity for neridronate through 2045, providing a long-term runway for a therapy that could become the first-ever approved treatment for CRPS-1 in the United States. The patent covers a novel method for selectively treating patients, a precision-medicine strategy that is already being deployed in the company's pivotal Phase 3 clinical trial, CRPS-RISE, which began enrolling patients earlier this year.

The Devastating Reality of an Invisible Illness

Complex Regional Pain Syndrome Type 1, formerly known as Reflex Sympathetic Dystrophy (RSD), is a rare and profoundly debilitating neurological condition. It typically emerges after a minor injury to a limb, such as a fracture or sprain, but triggers a cascade of pain and inflammation that is vastly disproportionate to the initial event. The condition affects an estimated 50,000 to 70,000 people in the U.S. and Europe, with no approved therapies to turn to.

Patients often describe the pain as a constant, torturous burning, throbbing, or stinging sensation. The condition frequently progresses through distinct phases. The initial "warm" phase, lasting up to a year, is marked by classic signs of inflammation: the affected limb becomes red, swollen, and hot to the touch. For many, this transitions into a chronic "cold" phase, where the limb becomes cool, pale or bluish, and is often accompanied by muscle atrophy and joint stiffness. The pain, however, remains a constant and disabling feature.

The impact on quality of life is catastrophic. The unrelenting pain and physical limitations make simple tasks impossible, leading to significant rates of unemployment and social isolation. The psychological toll is equally severe, with high incidences of depression, anxiety, and sleep disorders reported among patients.

A Precision Approach to a Complex Problem

Ambros Therapeutics is aiming to change this bleak outlook by targeting neridronate to a specific subgroup of patients most likely to benefit. The newly allowed patent, titled “Methods of Selectively Treating Complex Regional Pain Syndrome Type 1 (CRPS-1) Using Bisphosphonate Derivatives,” is central to this strategy. It protects a method that combines two key diagnostic indicators: a positive triple-phase bone scan (TPBS) showing increased bone activity and the clinical characteristics of the "warm" CRPS-1 subtype.

“The granting of this patent will mark an important step for Ambros and our orphan drug neridronate, and represents the potential for meaningful value creation among patients, investors and all stakeholders,” said Jay Hagan, Chief Executive Officer of Ambros Therapeutics, in a statement. “With an enhanced IP portfolio, we will be well-positioned to advance this important therapy through our pivotal program and potentially to patients with CRPS-1 who are in urgent need of new treatment options.”

This precision-medicine approach is the cornerstone of the ongoing CRPS-RISE Phase 3 trial. By enrolling only patients who meet these specific criteria, the company hopes to demonstrate a clear and significant benefit, a strategy that could prove more successful than previous, broader studies.

“By leveraging a positive triple-phase bone scan with specific clinical manifestations of CRPS-1, we believe we can identify patients that are significantly more likely to benefit from neridronate, representing an important advancement in the management of this disease and a meaningful step forward for patients,” added Gail Cawkwell, M.D., Ph.D., Chief Medical Officer of Ambros Therapeutics.

A Transatlantic Journey for a Promising Therapy

Neridronate is not a new molecule. The bisphosphonate was discovered and developed by Abiogen Pharma S.p.A. and is already approved and marketed in Italy for CRPS, as well as for other bone conditions like osteogenesis imperfecta and Paget's disease. Its established use in Europe, where it has demonstrated lasting pain reduction and a well-understood safety profile, provides a strong foundation for its development in the U.S.

Recognizing its potential, the U.S. Food and Drug Administration (FDA) has granted neridronate a trio of powerful designations intended to expedite the development of therapies for serious unmet needs. The Orphan Drug designation provides seven years of market exclusivity post-approval and financial incentives. The Fast Track designation allows for more frequent FDA interaction and a rolling review of the marketing application. Most significantly, the Breakthrough Therapy designation is reserved for drugs that have shown substantial improvement over existing therapies in early clinical evidence, providing intensive FDA guidance to ensure the most efficient development path.

Navigating the Path to Market

For Ambros Therapeutics, the combination of a robust patent portfolio, multiple FDA designations, and a targeted clinical trial design creates a formidable strategy. If the CRPS-RISE trial is successful, neridronate could enter the U.S. market as a first-in-class therapy with no direct competition. The extended patent protection until 2045, coupled with the seven years of orphan drug exclusivity, would secure a long period of commercial viability, allowing the company to recoup its investment and fund further research.

The pivotal CRPS-RISE study is a randomized, triple-blind, placebo-controlled trial expected to enroll 270 participants. It will evaluate the change in pain intensity over a 12-week period following four intravenous infusions of neridronate or a placebo. With primary completion estimated for late 2027, the medical community and patient advocates are watching with keen interest. For the thousands suffering from the daily agony of CRPS-1, the outcome of this trial could finally signal the arrival of a long-awaited, approved, and effective treatment.