NovoBioJect Boosts Active Methotrexate Levels in Phase 1b RA Trial

NovoBioJect Phase 1b Trial Design and MTX-polyglutamate Results

NovoBioJect, a fixed-dose combination of subcutaneous novobiocin and weekly oral methotrexate (MTX), increased intracellular levels of active methotrexate-polyglutamates by 38% compared with methotrexate alone in a phase 1b trial of patients with rheumatoid arthritis, Amplio Pharma announced October 1, 2026.¹ The biomarker effect reached statistical significance (P = .009) after a single dose, with no adverse events (AEs) reported other than mild, dose-dependent injection-site reactions.¹

Methotrexate remains first-line therapy for rheumatoid arthritis (RA), but ABCG2 transporter-mediated efflux limits intracellular accumulation of its active polyglutamate metabolites, and up to 60% of patients fail to reach remission on methotrexate monotherapy.¹ Novobiocin, a previously marketed antibiotic, is repurposed in NovoBioJect specifically to inhibit ABCG2 and retain more active drug inside immune cells.² Amplio Pharma said the phase 1b data support advancing into a phase 2a proof-of-concept study.¹

The phase 1b study was an open-label, cross-over, single ascending dose trial conducted at the Centre for Human Drug Research in Leiden, the Netherlands, enrolling 12 patients with RA on stable weekly methotrexate doses of 15 to 25 mg.¹ Novobiocin was administered subcutaneously at ascending doses of 80, 150, or 200 mg simultaneously with each patient's regular weekly methotrexate dose.¹ The primary biomarker outcome was intracellular accumulation of MTX-polyglutamates PG4 and PG5, long-chain metabolites considered pharmacological markers of methotrexate activity, measured in peripheral blood mononuclear cells.¹

NovoBioJect increased combined PG4 and PG5 accumulation by 38% compared with methotrexate alone (P = .009), with the effect observed after a single dose.¹ No AEs were reported other than mild, dose-dependent injection-site reactions.¹

NovoBioJect Mechanism, Remission Gap, and Phase 2a Plans

Methotrexate requires intracellular conversion to active polyglutamate metabolites to exert its anti-inflammatory effect, but ABCG2 transporter-mediated efflux exports methotrexate from target cells ahead of conversion, limiting the drug's effectiveness in many patients.² Novobiocin inhibits ABCG2 and is intended to retain more active methotrexate inside the immune cells driving RA inflammation, rather than requiring a higher methotrexate dose.² Methotrexate monotherapy produces remission in only 40% of patients with rheumatoid arthritis, according to Amplio Pharma.²

Composition-of-matter and use patents covering NovoBioJect have been granted in the United States and Europe, with protection expected to extend beyond 2040.¹ Amplio Pharma plans a phase 2a proof-of-concept study in the Netherlands in 2027, enrolling 100 newly diagnosed patients with RA over a 12-week treatment period.¹ Safety will be the phase 2a primary endpoint, with response rate, speed of onset, and MTX-polyglutamate biomarker levels as secondary endpoints.¹

The FDA and European Medicines Agency classify NovoBioJect as a single active pharmaceutical ingredient product centered on methotrexate.¹ Amplio Pharma, founded in 2020 and based in Amsterdam, is also initiating a Series A financing round of approximately €10 million to support the phase 2a program.¹

"An approach that increases intracellular polyglutamate levels pharmacologically, rather than by simply raising the methotrexate dose, is scientifically compelling," said Joel Kremer, MD, Pfaff Family Professor of Medicine, Albany Medical College, and president, Corrona Research Foundation, Albany, New York. "These early data justify a well-designed Phase 2 study to determine whether the biomarker effect translates into better clinical outcomes for patients."¹

"It is rare for a Phase 1b study to give such a clear read-out on the biomarker that matters," said Marguérite Mensonides-Harsema, PhD, CEO and co-founder, Amplio Pharma. "These results validate the mechanism behind NovoBioJect and give us and our investors a well-founded basis to move into a Phase 2a proof-of-concept study."¹

Amplio Pharma estimates 17.6 million people had rheumatoid arthritis worldwide in 2020, a population it projects will grow to 32 million by 2050, with roughly 400,000 new diagnoses annually across the United States and Europe combined.¹

REFERENCES:

1. Amplio Pharma. Amplio Pharma reports positive early clinical results for NovoBioJect, designed to make the world's most-used rheumatoid arthritis drug work for more patients. Published October 1, 2026. Accessed October 1, 2026. https://www.globenewswire.com/news-release/2026/10/01/3373040/0/en/amplio-pharma-reports-positive-early-clinical-results-for-novobioject-designed-to-make-the-world-s-most-used-rheumatoid-arthritis-drug-work-for-more-patients.html

2. Amplio Pharma. NovoBioJect. Accessed October 1, 2026. https://www.amplio-pharma.com/novobioject