A new clinical study from investigators at the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health (NIH) provides extremely promising data about an investigational oral antibiotic called zoliflodacin, which was well-tolerated and successfully cured most cases of uncomplicated gonorrhea when tested in a Phase II multi-center clinical trial.
Findings from the new study were published recently in The New England Journal of Medicine through an article entitled “Single-Dose Zoliflodacin (ETX0914) for Treatment of Urogenital Gonorrhea.”
“The rate of reported gonorrhea cases in the United States has increased 75 percent since the historic low in 2009, and antibiotic resistance has considerably reduced the number of treatment options for this disease,” commented NIAID Director Anthony S. Fauci, M.D., who was not directly involved in the study. “These encouraging research findings published today suggest that zoliflodacin has the potential to be a useful and easy-to-administer oral antibiotic for treating gonorrhea.”
Gonorrhea is a common sexually transmitted disease (STD) that affects both men and women, particularly young people ages 15 to 24 years. Gonorrhea is the second most commonly reported notifiable disease in the United States. In 2017, more than 550,000 U.S. cases of gonorrhea were reported. If untreated, gonorrhea infection can lead to pelvic inflammatory disease, ectopic pregnancy, infertility, and an increased risk of HIV infection. Pregnant women can pass the infection to their babies, who can develop blindness or life-threatening infections as a result.
Gonorrhea is caused by the bacterium Neisseria gonorrhoeae, which has progressively developed resistance to each of the antimicrobials used to treat it. As a result, in 2015, the U.S. Centers for Disease Control and Prevention (CDC) revised gonorrhea treatment guidelines to recommend dual therapy with injectable ceftriaxone and oral azithromycin to reduce the emergence of resistance to ceftriaxone.
Zoliflodacin (formerly known as ETX0914 and AZD0914), developed by Entasis Therapeutics based in Waltham, MA, represents a new type of oral antibiotic that inhibits DNA synthesis in a different way than currently approved antibiotics.
In the new study, researchers “randomly assigned eligible men and women who had signs or symptoms of uncomplicated urogenital gonorrhea or untreated urogenital gonorrhea or who had had sexual contact in the preceding 14 days with a person who had gonorrhea to receive a single oral dose of zoliflodacin (2 g or 3 g) or a single 500-mg intramuscular dose of ceftriaxone in a ratio of approximately 70:70:40,” the authors wrote. “A test of cure occurred within 6±2 days after treatment, followed by a safety visit 31±2 days after treatment. The primary efficacy outcome measure was the proportion of urogenital microbiologic cure in the microbiologic intention-to-treat (micro-ITT) population.”
The study took place from November 2014 through December 2015 and was led by Stephanie N. Taylor, M.D., of Louisiana State University Health Sciences Center in New Orleans. Study investigators recruited patients from sexual health clinics there and in Seattle; Indianapolis, IN; Birmingham, AL; and Durham, NC. The trial enrolled 179 participants (167 men and 12 non-pregnant women) ages 18 to 55 years with either symptoms of uncomplicated urogenital gonorrhea, untreated urogenital gonorrhea or sexual contact with someone with gonorrhea within 14 days before enrollment.
The authors reported that zoliflodacin cured all rectal gonorrheal infections (4 of 4 participants who received the 2-g dose and 6 of 6 participants who received the 3-g dose) as did ceftriaxone (3 of 3 participants). However, the investigational drug did not fare as well in treating patients with gonorrhea infections of the throat (pharyngeal): 67 percent of volunteers who received the 2-g dose (4 of 6 participants) and 78 percent of those who received the 3-g dose (7 of 9 participants) were cured. All of the participants (4 of 4) in the ceftriaxone group achieved a cure.
Zoliflodacin has been awarded fast-track status by the U.S. Food and Drug Administration for development as an oral treatment for gonococcal infections. It is expected to begin Phase III testing in The Netherlands, South Africa, Thailand, and the United States next year.