Data analysis of SOLITAIRE-U Phase III study of oral solithromycin to treat gonorrhea.-Cempra Inc.

Cempra has analyzed the data from the initial patient cohort of 262 patients in SOLITAIRE-U, a phase III study evaluating a single 1000 mg dose of oral solithromycin for treatment of uncomplicated genitourinary gonorrhea (GC), with or without concomitant chlamydia infection, compared with intramuscular ceftriaxone (500 mg) plus oral azithromycin (CTX/AZI) (1000 mg).

While solithromycin demonstrated high success rates of 80.5 percent in the microbiological intent to treat (mITT) population (defined as achievement of a negative urethral or cervical swab culture at day seven to eight among those patients who had culture confirmation of GC infection at baseline) and 91.3 percent in the microbiologically evaluable (ME) population (comprised of those patients with a positive baseline culture who returned for their follow-up evaluation), and showed a 100 percent success rate for females in the ME population, solithromycin did not demonstrate non-inferiority (NI) to standard of care treatment given the pre-specified 10 percent NI margin in the mITT population. The success rates for CTX/AZI in the mITT and ME populations were 84.5 percent and 100 percent, respectively.

Given the limited number of females and adolescents in SOLITAIRE-U, the National Institute of Allergy and Infectious Disease (NIAID) agreed to fund an expansion of the trial to enroll up to 76 women and adolescents (age 15-17) under a cooperative research and development agreement. Enrollment of this trial expansion has been much slower than anticipated.

Cempra believes that the small number of solithromycin treatment failures observed in SOLITAIRE-U could be reduced in an approval-enabling study with an adjustment to the dosing regimen, as it believes the treatment failures were most likely related to the duration of study drug exposure at the site of infection. The company plans to discuss its next steps with the GC program with NIAID and the FDA, as resistance to existing therapies for GC has created an urgent unmet medical need. In SOLITAIRE-U, no GC isolates demonstrated solithromycin resistance at baseline, and there was no emergence of solithromycin resistance in the isolates obtained at follow-up cultures.