SPL7013 Gel (VivaGel®) retains potent HIV-1 and HSV-2 inhibitory activity following vaginal administration in humans

Abstract

SPL7013 Gel (VivaGel(®)) is a microbicide in development for prevention of HIV and HSV. This clinical study assessed retention and duration of antiviral activity following vaginal administration of 3% SPL7013 Gel in healthy women. Participants received 5 single doses of product with ≥5 days between doses. A cervicovaginal fluid (CVF) sample was collected using a SoftCup™ pre-dose, and immediately, or 1, 3, 12 or 24 h post-dose. HIV-1 and HSV-2 antiviral activities of CVF samples were determined in cell culture assays. Antiviral activity in the presence of seminal plasma was also tested. Mass and concentration of SPL7013 in CVF samples was determined. Safety was assessed by reporting of adverse events. Statistical analysis was performed using the Wilcoxon signed-rank test with Bonferroni adjustment; p≤0.003 was significant. Eleven participants completed the study. Inhibition of HIV-1 and HSV-2 by pre-dose CVF samples was negligible. CVF samples obtained immediately after dosing almost completely inhibited (median, interquartile range) HIV-1 [96% (95,97)] and HSV-2 [86% (85,94)], and activity was maintained in all women at 3 h (HIV-1 [96% (95,98), p = 0.9]; HSV-2 [94% (91,97), p = 0.005]). At 24 h, >90% of initial HIV-1 and HSV-2 inhibition was maintained in 6/11 women. SPL7013 was recovered in CVF samples obtained at baseline (46% of 105 mg dose). At 3 and 24 h, 22 mg and 4 mg SPL7013, respectively, were recovered. More than 70% inhibition of HIV-1 and HSV-2 was observed if there was >0.5 mg SPL7013 in CVF samples. High levels of antiviral activity were retained in the presence of seminal plasma. VivaGel was well tolerated with no signs or symptoms of vaginal, vulvar or cervical irritation reported. Potent antiviral activity was observed against HIV-1 and HSV-2 immediately following vaginal administration of VivaGel, with activity maintained for at least 3 h post-dose. The data provide evidence of antiviral activity in a clinical setting, and suggest VivaGel could be administered up to 3 h before coitus.

Trial registration: The study is registered at ClinicalTrials.gov under identifier: NCT00740584.

Figure 1. Recovery of CVF samples using the SoftCup.

Weight of post-dose CVF samples as a percentage of the actual weight of SPL7013 Gel administered vaginally compared to the position in the sampling sequence (A) and the time post-dose (B). Data represent the average from the eleven study subjects. Error bars denote standard error of the mean.

Figure 2. Recovery of SPL7013 using the SoftCup.

Mass of SPL7013 (mg) recovered in CVF samples from each subject taken at baseline (within 2–10 minutes post-dose) (0), 1, 3, 12 and 24 h post-dose (A). Average recovery of SPL7013 as a percentage dose of SPL7013 administered (105 mg) (B). Error bars denote standard error of the mean.

Figure 3. HIV-1 and HSV-2 inhibitory activity of post-dose CVF samples.

The percent inhibition of HIV-1 replication mediated by post-dose CVF samples from each subject compared to HIV-1 infected cells incubated in the absence of CVF sample. All samples recovered in 20 mL of saline were diluted an additional 1∶2 (total dilution of samples ∼ 1∶40) (A). The percent inhibition of HSV-2 replication mediated by post-dose CVF samples from each subject compared to HSV-2 infected cells incubated in the absence of CVF sample. All samples recovered in 20 mL of saline were diluted an additional 1∶50 (total dilution of samples ∼ 1∶1000) (B). Data are from three independent assays. Error bars denote standard error of the mean.

Figure 4. Impact of seminal plasma on the HIV-1 and HSV-2 inhibitory activity of post-dose CVF samples.

Inhibition of HIV-1 replication by post-dose CVF samples from subjects 1 (A), 3 (B) and 5 (C) performed in the absence and presence of 12.5% seminal plasma (SP). Inhibition of HSV-2 replication by post-dose CVF samples from subjects 1 (D), 3 (E) and 5 (F) performed in the absence and presence of 10% seminal plasma. Data are from three independent assays. Error bars denote standard error of the mean.

Figure 5. Relationship between recovered mass and concentration of SPL7013, and HIV-1 and HSV-2 inhibitory activity of post-dose CVF samples.

The inhibition of viral replication in post-dose CVF sample from all participants as a function of either the mass of recovered SPL7013 for HIV-1 (A) and HSV-2 (B) or the concentration of SPL7013 in the original undiluted samples for HIV-1 (C) and HSV-2 (D).

Figure 6. Contribution of SPL7013 to antiviral activity in SPL7013 Gel.

Inhibition of HIV-1 (A) and HSV-2 (B) replication of 2 g of SPL7013 Gel or Placebo Gel combined with 0.5 g of pooled human cervicovaginal secretions and diluted in 20 mL of saline. Cytotoxicity of the samples in TZM-bl cells (C) and HEL cells (D). Dilution denotes fold dilutions of CVF sample in medium that were initially recovered in saline. Data are from three independent assays. Error bars denote standard error of the mean.