May 07, 2021
A plant-based fusion protein is safe and effective for inducing favorable immune modulation in patients with mild to moderate ulcerative colitis with no immune suppression–side effects reported.
OPRX-106, an orally administered BY2 plant cell–expressing recombinant TNF fusion protein, has demonstrated effectiveness as an anti–TNF-alpha therapy, according to Einat Almon, PhD, of Protalix Biotherapeutics, and colleagues.
"Oral immune therapy is based on the concept of oral administration of nonabsorbable compounds which target the gut immune system to redirect the systemic immune system toward an anti-inflammatory direction, without immunosuppression," the researchers said.
A phase 1 study of OPRX-106 in healthy human volunteers showed safety and immune modulatory effects at doses of 2, 8, or 16 mg/day.
In this phase 2a clinical trial published in the Journal of Clinical Gastroenterology, the researchers enrolled 24 patients with ulcerative colitis (11 male and 13 female) aged 23-73 years, with an average age of 42.6 years. Patients received either 2 mg or 8 mg of OPRX-106 at least once daily for 8 weeks. All patients were monitored for 6 hours after receiving medication on day 1 and week 8 for pharmacokinetic sampling, and a lower endoscopy was performed at week 8.
After 8 weeks, 67% of the patients demonstrated clinical response and 28% showed clinical remission.
Clinical response and clinical remission were defined by a specific set of criteria including improvement in the Mayo score. Clinical response was a "decrease in the Mayo score of at least 3 points, decrease in the subscore for rectal bleeding of at least 1 point, [and] a rectal bleeding subscore of 0 or 1." Clinical remission at week 8 was defined as "clinically symptom-free, Mayo score of ≤2 with no individual subscore exceeding 1 point after treatment, histopathological improvement in Geboes histologic grading from baseline to week 8, improvement in high sensitivity C-reactive protein levels from baseline to week 8, improvement in fecal calprotectin levels from baseline to week 8, and changes in systemic immune modulation parameters from baseline to week 8."
In addition, 89% of the patients experienced some degree of improvement in their Mayo scores, 61% had mucosal improvement, and 33% achieved mucosal healing.
No side effects associated with general immune suppression were reported. No patients discontinued the study because of adverse events, the researchers said. However, overall, 40 adverse events were reported in 15 patients; 95% of these were mild to moderate and 40% were reported as treatment related. No differences appeared in adverse events related to the two doses.
Evidence of a systemic anti-inflammatory effect was seen with a decrease in serum levels of the pro-inflammatory cytokines interleukin-6 and interferon-gamma that correlated with the clinical response, the researchers noted. Similarly, an increase in the CD3+CD4+CD25+Foxp3+ subset of suppressor lymphocytes correlated with clinical response.
The study findings were limited by the small sample size, open-label design, and lack of control subjects. However, by targeting the gut immune system, the drug "may provide an answer to the long-term immune suppression encountered in patients with chronic disorders who use these agents for prolonged periods of time, in addition to loss of response due to neutralizing antibodies," they concluded.
Findings Provide Foundation for Further Research
"Conducting a study of a novel treatment for ulcerative colitis is valuable and timely because the available options are limited," Atsushi Sakuraba, MD, of the University of Chicago, said in an interview. "The currently available TNF antagonists are administered intravenously or subcutaneously and bear the risk of infectious complications, so the development of an agent that can be administered orally with fewer side effects is of importance."
Although the data are preliminary, Sakuraba emphasized that the take-home message for clinicians is that "the present open-label study consisting of a small number of subjects demonstrated that OPRX-106 was effective and safe in active ulcerative colitis, so further investigation is warranted. Larger-powered, randomized, placebo-controlled studies are needed to confirm these findings."
The study was supported by Protalix Biotherapeutics; Almon and several coauthors are employed by Protalix Biotherapeutics. Sakuraba had no financial conflicts to disclose.