Tekmira Pharmaceuticals said last week that it has stopped a phase I study of its siRNA-based hypercholesterolemia drug ApoB SNALP.
While the drug was well tolerated and showed some signs of clinical activity, Tekmira said that it has put the phase I program on hold in order to select a new siRNA and drug-delivery formulation for development. The new agent is expected to be "several-fold more potent than the current formulation," the company said.
In the recently completed phase I trial, 23 patients were enrolled, 17 of which received a single dose of the drug at one of seven different dosing levels, according to the company. The other six received placebo.
Tekmira said that the drug was well tolerated and showed no evidence of toxicity. "Of the two subjects treated at the highest dose level, one subject experienced flu-like symptoms consistent with stimulation of the immune system caused by the ApoB siRNA payload," the company noted. "The other subject treated at the highest dose level experienced no side effects. Based on the potential for the immune stimulation to interfere with further dose escalation, Tekmira decided to conclude the trial."
The company said it plans to re-initiate the phase I program in the second half of the year.
Secondary endpoints included drug activity, including the reduction of apolipoprotein B protein and low-density lipoprotein. "Of the two subjects treated at the highest dose, the average transient reduction of ApoB protein and LDL cholesterol was 21.1 percent and 16.3 percent, respectively," Tekmira said.
Complete data from the study will be presented at an upcoming scientific meeting, it added.