OrthoTrophix Announces Early Completion of Enrollment in Phase 2b Trial of TPX-100 in Knee Osteoarthritis

FOSTER CITY, Calif., Feb. 24, 2026 /PRNewswire/ — OrthoTrophix, Inc., a privately held biopharmaceutical company developing novel investigational therapies for osteoarthritis, today announced the early completion of the planned patient enrollment in its Phase 2b clinical trial evaluating intra-articular TPX-100 for the treatment of knee osteoarthritis (OA). The multicenter U.S. trial was initiated in May 2025 and is expected to complete in the first quarter of 2027.

TPX-100 is OrthoTrophix’s lead therapeutic candidate and is being developed as a potential disease-modifying osteoarthritis drug (DMOAD) — designed not only to improve symptoms, but also to slow or halt disease progression. 

In a prior randomized, placebo-controlled Phase 2a trial, TPX-100 was associated with a favorable safety profile and statistically significant improvements in knee function compared to placebo. TPX-100-treated knees also showed attenuation of pathological subchondral bone-shape change (“B-score”), an objective structural imaging biomarker increasingly associated with osteoarthritis progression and risk of joint replacement.

While osteoarthritis has traditionally been characterized as a cartilage disease, a growing body of evidence supports a central role for subchondral bone pathology in both symptom development and structural progression. Large-scale natural history studies involving more than 9,000 knees have shown that pathological bone-shape changes may precede measurable cartilage deterioration and are strongly associated with worsening symptoms and joint failure. Post hoc MRI analyses from the Phase 2a study showed statistically significant reductions in femoral bone-shape deterioration in TPX-100–treated knees compared to placebo (McGuire et. al., Arthritis Research & Therapy, 2021).

The Phase 2b trial, entitled “A 53-Week Study Evaluating the Safety and Efficacy of Intra-Articular Injections of TPX-100 in Patients with Mild to Severe Tibiofemoral Osteoarthritis of the Knee,” is designed to further evaluate the clinical and structural findings observed in Phase 2a. Additional study details are available at ClinicalTrials.gov (NCT06865079).

Dawn McGuire, M.D., FAAN, OrthoTrophix’ Chief Medical Officer, stated: “The completion of enrollment ahead of schedule reflects strong investigator engagement and underscores the high unmet medical need for new osteoarthritis therapies. Subchondral bone pathology is increasingly recognized as a key structural driver of knee osteoarthritis progression. By targeting bone-shape deterioration, TPX-100 represents a differentiated approach to disease modification.  If confirmed in Phase 2b, our findings could support advancement of TPX-100 into late-stage development and help redefine how structural progression in osteoarthritis is measured and treated.”

About OrthoTrophix, Inc.

OrthoTrophix, Inc., based in the San Francisco Bay Area, is a privately held biopharmaceutical company focused on the developing first-in-class therapies that protect and preserve joint integrity in osteoarthritis and related hard tissue disorders. Founded in 2011, OrthoTrophix is advancing targeted disease-modification strategies to slow or stop disease progression and improve long term patient outcomes. OrthoTrophix has partnered with American Regent, Inc. (https://americanregent.com/) on its DMOAD candidate, TPX-100, for the U.S. market and retains the rights for the rest of the world.

This press release contains “forward-looking” statements. These statements involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements include statements regarding product development and cannot be guaranteed. OrthoTrophix undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect OrthoTrophix’ business.

Company Contact

Yoshi Kumagai

President and CEO

Tel: (510) 488-3832

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SOURCE OrthoTrophix, Inc.