Trial to Assess the Efficacy of F598 in Preventing an Experimental Urethral Infection With N. Gonorrhoeae in Healthy Males

The study is comprised of 8 phases: 1. Screening (Visits 1 and 2) 2. F598 administration (Visit 3) 3. Inoculation (Visit 4) 4. Observation (Visits 5 - 8, as needed) 5. Definitive antibiotic treatment (Visit 9) 6. Test of cure (Visit 10) 7. Confirmatory interaction (Visit 11) 8. Final pharmacokinetic (PK)/pharmacodynamic (PD)/anti-drug antibody determination (Visit 12) For the purposes of standardization, Day 1 of the study will be considered the day of inoculation. During the Screening phase, prospective subjects will undergo informed consent and will be reviewed for their compatibility with the eligibility criteria. Those subjects who meet all of the Inclusion criteria and none of the Exclusion criteria will be enrolled. Following enrollment, subjects must undergo a repeat urine screen for C. trachomatis, N. gonorrhoeae and T. vaginalis (Days -17 to -4). If the second urine screening test is negative, subjects will enter the F598 administration phase. Subjects will return to the study site and will be randomized to one of four open-label groups: Control (no treatment) or treatment with F598 at one of three doses. Following F598 administration or assignment to the Control group, subjects must return to the study site for inoculation with N. gonorrhoeae within 2 weeks. Thus, F598 will be administered on any one of Days -12 to -2. During the inoculation phase, subjects will return to the study site and receive an inoculum of N. gonorrhoeae in the anterior urethra. A third and final urine screen for C. trachomatis, N. gonorrhoeae and T. vaginalis will be obtained immediately before inoculation. Once subjects have been inoculated with N. gonorrhoeae, they will enter the observation phase and will return to the study site daily for up to 5 days for a physical examination (in particular, for evidence of urethral discharge) and a urine sample for evidence of infection (NAAT and culture) as well as blood for F598 PK/PD and safety labs. The observation phase will end and definitive antibiotic therapy will be administered when any one of four criteria is met: 1. The subject requests antibiotic treatment 2. The subject is found to by symptomatic (discharge, urethral discomfort) 3. The subject has reached Day 6 of the study Thus, depending on the circumstances, definitive antibiotic therapy can be administered between Days 2 - 6, inclusive. A follow-up visit at the study site will be conducted 3 - 5 days after definitive antibiotic therapy has been administered to ensure treatment response. Thus, depending on when the subject received antibiotics, this visit could occur between Days 5 - 11, inclusive. A physical examination will be performed and urine for evidence of infection (NAAT) as well as blood for F598 PK/PD will be obtained. A confirmatory interaction with the subject will occur at the study site 7 - 10 days after the follow-up visit to confirm the subject's response and answer any questions the subject may have. Thus, depending on when the subject had his follow-up visit, the confirmatory visit could occur between Days 12 - 21, inclusive. Blood for F598 PK/PD, anti-F598 antibodies and safety labs will be obtained. A final visit will occur approximately 8 weeks after inoculation (days 52 - 60) to obtain serum for PK/PD and anti-F598 antibodies.