- CRPS-RISE designed to support FDA regulatory submission for potential approval of neridronate in patients with CRPS-1
- FDA has previously granted neridronate with Breakthrough Therapy, Fast Track, and Orphan Drug designations
IRVINE, Calif., June 08, 2026 (GLOBE NEWSWIRE) -- Ambros Therapeutics, Inc. today announced that the first patient has been dosed in its pivotal CRPS-RISE Phase 3 clinical trial evaluating neridronate versus placebo for the treatment of Complex Regional Pain Syndrome Type 1 (CRPS-1). CRPS-1 is a severe, debilitating rare disease with an estimated 65,000 new cases annually in the United States.
“The first patient dosed in our CRPS-RISE trial represents a significant milestone in our mission to develop neridronate as a potential breakthrough therapy for patients with CRPS-1, a condition with no FDA-approved pharmacological therapies,” said Jay Hagan, Chief Executive Officer of Ambros Therapeutics. “This is an important milestone in the initiation of this pivotal program as we work to advance a meaningful new treatment option and potentially redefine the standard of care for patients living with CRPS-1 in the United States.”
“CRPS-1 is a debilitating condition where patients often face limited and suboptimal treatment options. By selecting patients based on characteristics aligned with neridronate’s potential activity, we aim to evaluate its clinical benefit in a more targeted way and advance a program that reflects both the biology of the disease and the needs of patients,” said Gail Cawkwell, M.D., Ph.D., Chief Medical Officer of Ambros Therapeutics.
CRPS-RISE is a multicenter, randomized, triple-blind, placebo-controlled clinical trial designed to assess the efficacy, safety and tolerability of neridronate in patients with warm CRPS-1. The trial will evaluate approximately 270 participants randomized 1:1 to receive either intravenous (IV) neridronate or placebo. To be eligible for the trial, participants must have a confirmed CRPS-1 diagnosis per the Budapest Clinical Criteria, a known precipitating event (e.g. fracture, sprain, contusion), CRPS-1 duration of 6 months or less and moderate to severe pain. Additionally, participants must have characteristics that we believe make them more likely responders to neridronate treatment: a positive triple phase bone scan and specific attributes of the warm CRPS-1 subtype. Following an initial screening period of two to six weeks, participants will receive four IV infusions over 10 days of either 100 mg neridronate (400 mg total dose) or placebo followed by a post-treatment period through week 12.
The primary efficacy endpoint is change in pain intensity from baseline to week 12 as measured on an 11-point Numerical Rating Scale. Key secondary endpoints include other measures of pain reduction and patient reported outcomes. The program includes a registry for long-term outcomes and an opportunity for CRPS-RISE participants with active disease who completed the study to receive neridronate.
“For the first time, a large clinical trial for patients with CRPS-1 is leveraging a precision medicine approach to enhance patient identification and inclusion criteria, a significant breakthrough in the development of therapies in this patient population,” said Stephen Bruehl, Ph.D., Professor of Anesthesiology, Vanderbilt University School of Medicine, and Scientific Advisor to Ambros Therapeutics. “The precision medicine inclusion criteria in the CRPS-RISE trial build upon research undertaken by leading institutions focused on CRPS including our team’s work to enhance our understanding of CRPS-1, and I’m pleased to be actively involved in the CRPS-RISE trial.”
Based on interactions with the FDA, we believe that positive results from a single pivotal trial such as CRPS-RISE could support a potential U.S. approval. Neridronate has been granted FDA Breakthrough Therapy, Fast Track, and Orphan Drug designations.
More information about CRPS-RISE Phase 3 Clinical Trial is available on the clinical trial website (CRPS-RISE) and at clinicaltrials.gov (NCT07210515).
About Neridronate
Neridronate is a differentiated bisphosphonate that was discovered and developed by Abiogen Pharma S.p.A. Neridronate is approved and marketed in Italy for the treatment of Complex Regional Pain Syndrome (CRPS); clinical studies have demonstrated lasting pain reduction along with improvements in other CRPS related symptoms. Beyond CRPS, neridronate is also approved in Italy for osteogenesis imperfecta and Paget’s disease. Its well-established safety and tolerability profile and therapeutic benefits make it a potential promising treatment for patients with CRPS-1 worldwide. Recognizing its potential, the U.S. Food and Drug Administration (FDA) has granted neridronate Breakthrough Therapy, Fast Track, and Orphan Drug designations for the treatment of CRPS.
About Complex Regional Pain Syndrome Type 1 (CRPS-1)
Complex Regional Pain Syndrome Type 1 (CRPS-1; formerly known as RSD or Reflex Sympathetic Dystrophy) is a rare and debilitating condition typically following a limb injury. There are currently no FDA-approved medicines available to treat this high unmet need patient population. The condition is characterized by intense pain that can be continuous in the affected limb such as the arm, leg, hand or foot. Patients with CRPS-1 often experience an evolving condition commencing with a “warm” phase that typically predominates in the first year after onset where inflammation and other mechanisms cause the affected limb to become red, swollen, warm, and hypersensitive to pain. In many patients, the disease progresses to a chronic “cold” phase, where the affected limb changes its presentation and patients face ongoing, debilitating pain.
About Ambros Therapeutics
Ambros Therapeutics, headquartered in Irvine, California, is a clinical-stage biotechnology company focused on the development of innovative and transformative medicines for diseases with high unmet medical need. Ambros’ lead investigational program, neridronate, is currently being evaluated in an ongoing pivotal Phase 3 clinical trial (CRPS-RISE) for warm CRPS-1. Neridronate has the potential to become the first and only FDA-approved pharmacological therapy addressing patients with CRPS-1.
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