PRTX-100: Phase Ib data

Final data from a dose-escalation, South African Phase Ib trial in 37 patients with active RA who were receiving methotrexate showed that once-weekly PRTX-100 missed the primary disease activity response endpoint of improving the number of patients with DAS28-CRP score <3.2 points at week 6 vs. placebo. Protalex said that PRTX-100 did not reduce C-reactive protein (CRP) levels, a component of the DAS28-CRP scale, even in patients who achieved a reduction in swollen and tender joint count and global Visual Analogue Scale (VAS) scores after treatment. The company therefore conducted a post-hoc analysis of the data using Clinical Disease Activity Index for RA (CDAI) scale, which does not include a CRP component. The post-hoc analysis showed that 1 of 8 patients in each of the placebo, 0.15 µg/kg PRTX-100 and 0.45 µg/kg PRTX-100 groups achieved a CDAI score <=10 points on >=2 consecutive visits. Additionally, 2 of 8 patients receiving 0.9 µg/kg PRTX-100 and 2 of 5 patients receiving 1.5 µg/kg PRTX-100 achieved a CDAI score <=10 points on >=2 consecutive visits and maintained a CDAI score <10 points through week 16. In the 1.5 µg/kg PRTX-100 group, 2 patients achieved a CDAI score <=6 points, 1 patient achieved a CDAI score <10 points and 1 patient achieved a CDAI score of 10.1 points at >=1 visit. Based on the data, Protalex said it believes that DAS28-CRP is not a meaningful way to measure the primary disease activity response of PRTX-100. The maximum tolerated dose (MTD) was not reached. Patients received once-weekly 0.15-1.5 µg/kg PRTX-100 or placebo for 4 weeks. ...