Opexa Therapeutics, Inc. (NASDAQ: OPXA), a company developing Tovaxin®, a novel T-cell therapy for multiple sclerosis (MS), today presented important efficacy data at the American Academy of Neurology (AAN) 63rd Annual Meeting.
Clyde Markowitz, M.D., director of the Multiple Sclerosis Center at the University of Pennsylvania, professor of neurology at the University of Pennsylvania School of Medicine and member of Opexa's Scientific Advisory Board, presented the clinical data during a poster session at AAN. The presentation highlighted important efficacy data from Opexa's Phase IIb TERMS clinical trial in a subpopulation of patients that had previously not been exposed to or taken any drugs for the treatment of their MS.
In this treatment-free or "naïve" subpopulation, patients treated with Tovaxin demonstrated a significant improvement in Annualized Relapse Rate (ARR) compared to those on placebo. In patients who had at least one relapse in the 12 months prior to enrolling in the study and who had no previous exposure to MS therapy.
"The analysis conducted on this patient subgroup provides critical information on clinical trial design," stated Dawn McGuire, M.D., Chair of Opexa's Scientific Advisory Board. "Patients naïve to previous therapy, including those newly diagnosed, represent an excellent target population for future studies. Eliminating a possible "legacy" effect due to previous exposure to MS drugs may increase study power to detect a treatment effect. Results identified in this population are encouraging and support Opexa's plans to initiate a pivotal clinical study later this year."
Prior treatment with Disease Modifying Therapies (DMTs), especially immunosuppressants or broad acting T-cell therapies, may influence the ARR in the placebo group by imparting a long-term benefit or "legacy" effect. This could explain the observed decline in ARR for placebo controls in more recent MS clinical trials. The impact of prior therapies on the placebo group would indicate that despite a washout period to remove potential DMTs as defined by pharmacokinetics, a legacy effect might persist.
"These results provide us with useful information regarding future clinical trial design and eventual market positioning for Tovaxin," commented Neil K. Warma, President and CEO of Opexa. "There are several reports which speak to the large number of patients who decide not to initiate treatment once they have been diagnosed or stop treatment in the first one to two years due to side effects and compliance issues. In the population included in the AAN presentation, we were surprised to find that many of the patients had decided not to take any medication for several years following their initial diagnosis of MS and truly remained treatment-free right up until the start of our Phase IIb trial. For over half of the total population that enrolled in the TERMS trial, Tovaxin was their first choice of treatment, despite there being several drugs on the market. We have always maintained that Tovaxin could be very well positioned to capture newly diagnosed patients and non-compliant patients who, today, are faced with limited treatment options. This analysis strongly supports that belief and, hopefully, provides more encouragement to these patients. We believe that Tovaxin has the potential to treat all MS patients, not only these subgroups, but our understanding of the response rates in the various subpopulations will contribute to the optimal design of future clinical studies."