Safety, acceptability, and pharmacokinetics of a monoclonal antibody-based vaginal multipurpose prevention film (MB66): A Phase I randomized trial

Abstract

Background: MB66 film is a multipurpose prevention technology (MPT) product with monoclonal antibodies (mAbs) against HIV-1 (VRC01-N) and HSV-1 and 2 (HSV8-N). The mAbs were produced by transient expression in Nicotiana benthamiana (N). We conducted a Phase I clinical trial to assess the safety, pharmacokinetics (PK), and ex vivo efficacy of single and repeated doses of MB66 when used intravaginally.

Methods and findings: The clinical trial enrolled healthy reproductive-aged, sexually abstinent women. In Segment A, 9 women received a single MB66 film which was inserted into the vaginal posterior fornix by a clinician. In Segment B, 29 women were randomly assigned to MB66 (Active) or Placebo film groups and were instructed to insert 1 film vaginally for 7 consecutive days. Visits and clinical sampling occurred predose and at various time points after single and repeated film doses. The primary endpoint was number of adverse events (AEs) Grade 2 or higher related to product use. Secondary endpoints included film dissolution rate, Nugent score (a Gram stain scoring system to diagnose bacterial vaginosis), vaginal pH, post-use survey results, cytokine concentrations in cervicovaginal lavage (CVL) specimens (assessed by Luminex assay), mAb concentrations in vaginal fluid collected from 4 sites (assessed by ELISA), and HIV and HSV neutralization activity of CVL samples ex vivo (assessed by TZM-bl and plaque reduction assay, respectively). The product was generally safe and well tolerated, with no serious AEs recorded in either segment. The AEs in this study were primarily genitourinary in nature with the most commonly reported AE being asymptomatic microscopic hematuria. There were no differences in vaginal pH or Nugent scores or significant increases in levels of proinflammatory cytokines for up to 7 days after film insertion in either segment or between Active and Placebo groups. Acceptability and willingness to use the product were judged to be high by post-use surveys. Concentrations of VRC01-N and HSV8-N in vaginal secretions were assessed over time to generate pharmacokinetic curves. Antibody levels peaked 1 hour postdosing with Active film (median: 35 μg/mL) and remained significantly elevated at 24 hours post first and seventh film (median: 1.8 μg/mL). Correcting for sample dilution (1:20), VRC01-N concentrations ranged from 36 to 700 μg/mL at the 24-hour time point, greater than 100-fold the IC50 for VRC01 (0.32 μg/mL); HSV8-N concentrations ranged from 80 to 601 μg/mL, well above the IC50 of 0.1 μg/m. CVL samples collected 24 hours after MB66 insertion significantly neutralized both HIV-1 and HSV-2 ex vivo. Study limitations include the small size of the study cohort, and the fact that no samples were collected between 24 hours and 7 days for pharmacokinetic evaluation.

Conclusions: Single and repeated intravaginal applications of MB66 film were safe, well tolerated, and acceptable. Concentrations and ex vivo bioactivity of both mAbs in vaginal secretions were significantly elevated and thus could provide protection for at least 24 hours postdose. However, further research is needed to evaluate the efficacy of MB66 film in women at risk for HIV and HSV infection. Additional antibodies could be added to this platform to provide protection against other sexually transmitted infections (STIs) and contraception.

Trial registration: ClinicalTrials.gov NCT02579083.

Conflict of interest statement

I have read the journal's policy and the authors of this manuscript have the following competing interests: KJW and LZ own Mapp Biopharmaceutical Inc., a company that intends to commercialize antibody-based products. TRM, TN and MB work for Mapp Biopharmaceutical Inc. The other authors have declared that no competing interests exist.

Figures

Fig 1. MB66 film example and composition.

Fig 2

MB66-01 study Segments A and B schemata with target enrollment.

Fig 3. Diagram of MB66-01 enrollment.

Fig 4

VRC01-N and HSV8-N concentrations (represented by medians with interquartile ranges) in cervicovaginal TearFlo samples in Segments A and B (Active film group only). (A). Segment A, VRC01-N: All 4 sites significantly elevated at 1 hour (p < 0.001 for all site comparisons) and 4 hours (p < 0.001 for cervical os, ectocervix, and mid vagina sites; p = 0.007 for distal vagina) post single film insertion compared to respective baseline concentrations. Cervical os (p = 0.046) and ectocervix (p = 0.02) were elevated 24 hours post film insertion. Mid (p = 0.09) and distal vagina (p = 0.54) were not significantly elevated 24 hours post film insertion. (B). Segment A, HSV8-N: All sites were significantly elevated at 1 hour and 4 hours post single film insertion (p < 0.001 for all comparisons) but not at the 24-hour time point. (C). Segment B, VRC01-N: All 4 sites were significantly elevated at 1 (p < 0.001 for all site comparisons) and 4 (p < 0.001 for all site comparisons) hours following first film insertion compared to each site’s respective baseline concentration. Concentrations at all 4 sites 24 hours after first film and 24 hours after seventh film remained significantly elevated compared to Baseline (p < 0.001 for distal vagina, ectocervix, and mid vagina sites and p = 0.01 for cervical os for Baseline vs. 24 hours post first film, and p < 0.001 for distal vagina, ectocervix, and mid vagina sites and p = 0.0007 for cervical os for Baseline vs. 24 post seventh film). (D). Segment B, HSV8-N: All 4 sites were significantly elevated at 1 and 4 hours following first film insertion compared to Baseline concentrations. Concentrations at all 4 sites at 24 hours after first film and 24 hours after seventh film remained significantly elevated compared to Baseline (p < 0.001 for all comparisons).

Fig 5

Viral neutralization and antibody pharmacokinetics (represented by means ± SEMs) in CVLs in Segments A and B (Active film group only). Neutralization percent is represented by solid lines/circles () (left y axis), and antibody concentration is represented by dashed lines/open triangles () (right y axis) in each graph. (A). VRC01-N concentration and HIVQ23-17 neutralization in Segment A were significantly increased at 24 hours post single film insertion compared to both Baseline (p = 0.006 and 0.01, respectively) and 7 days post single film insertion (p = 0.006 and 0.02, respectively). (B). HSV8-N concentrations in Segment A were significantly increased at 24 hours post single film insertion compared to both Baseline (p = 0.04) and 7 days post single film insertion (p = 0.01). All CVL samples from 24 hours post film insertion exhibited 100% HSV neutralization; however, the omnibus F test p-value did not reach statistical significance (p = 0.052). (C). VRC01-N concentration and HIVQ23-17 neutralization in Segment B were significantly elevated 24 hours after first film and 24 hours after seventh film compared to Baseline (p < 0.001 for all comparisons). (D). In Segment B, HSV8-N concentrations 24 hours after first film and 24 hours after seventh film did not differ significantly from Baseline (p = 0.056, Group x Visit interaction), but HSV neutralization was significantly increased at 24 hours post first film (p = 0.003) and 24 hours post seventh film compared to Baseline (p = 0.001).

Fig 6

Forest plots of cytokines in CVLs: (A). The ratio (relative median ± 95% confidence interval) of Visit 3 (24 hours after single film) to Baseline concentrations in Segment A, and (B). The ratio (relative median ± 95% confidence interval) of Active film Visit 4 (24 hours after seventh film) to Placebo film Visit 4 concentrations in Segment B. No significant increases in cytokine concentrations were observed following Active film insertion or in Active film vs. Placebo film group comparisons.