XBiotech (NASDAQ: XBIT) has announced a halt to its clinical program in rheumatological diseases following the outcome of a Phase II trial of its drug candidate, Natrunix, for rheumatoid arthritis (RA). The study failed to meet its primary endpoint, and the company cited "substantial irregularities" that complicate the interpretation of the findings. The announcement led to a significant drop in XBiotech's stock value and prompted investigations into potential securities fraud.
The Phase II study (NCT05363917) enrolled approximately 230 subjects with moderate to severe RA. It evaluated Natrunix, a True Human antibody, in combination with methotrexate (MTX) against placebo with MTX. The primary endpoint was the American College of Rheumatology (ACR) 20 response rate after 12 weeks of treatment.
Data Irregularities and Impact
According to XBiotech, the trial was affected by irregularities at the highest enrolling clinical sites, including instances of subjects being enrolled multiple times. This raised concerns about the integrity and reliability of the data, leading the company to pause further rheumatology studies, including those planned for ankylosing spondylitis.
"Although the study did not meet efficacy endpoints, discrepancies found during data analysis suggest caution in interpreting results," the company stated. The findings are under analysis to determine their implications and guide potential future studies with Natrunix.
Market Reaction and Legal Scrutiny
The news of the trial's failure and subsequent program halt led to a 27% decrease in XBiotech's stock value. Several law firms, including The Schall Law Firm and Wolf Haldenstein Adler Freeman & Herz LLP, have announced investigations into XBiotech for potential violations of securities laws, focusing on whether the company issued false or misleading statements or failed to disclose pertinent information to investors.
Natrunix: Previous Expectations and Future Uncertainty
GlobalData’s Pharmaceutical Intelligence Centre had previously estimated global sales of Natrunix (bermekimab) to reach $179 million by the end of 2024, growing to $488 million by the end of 2025. However, these projections are now uncertain given the clinical trial setback.
Context within Rheumatoid Arthritis Treatment Landscape
The RA treatment landscape is competitive, with established therapies and emerging options. Bristol Myers Squibb recently announced positive topline results from Phase III trials of Sotyktu (deucravacitinib) for active psoriatic arthritis, demonstrating the ongoing innovation in this therapeutic area. The failure of XBiotech's Natrunix highlights the challenges in developing effective treatments for rheumatic diseases.
