Trial Outcomes & Findings for Safety and Tolerability of AAV8 Delivery of a Broadly Neutralizing Antibody in Adults Living With HIV: a Phase 1, Dose-escalation Trial (NCT NCT03374202)

Volunteers were recruited for the study at the NIH Clinical Center in Bethesda, Maryland, USA. Adults who were HIV infected but in general good health and had been taking the same HIV medicine for at least 3 months were enrolled.

Safety and Tolerability of AAV8 Delivery of a Broadly Neutralizing Antibody in Adults Living With HIV: a Phase 1, Dose-escalation Trial

Participants recorded the occurrence of solicited symptoms on a diary card for 7 days after study product administration and reviewed the diary card with clinic staff at a follow up visit. Participants were counted once for each symptom at the worst severity if they indicated experiencing the symptom more than one time at any severity during the reporting period. The number reported for "Any Local Symptom" is the number of participants reporting any local symptom at the worst severity. Reactogenicity grading (Mild, Moderate, Severe) was done using the U.S. Department of Health and Human Services, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Division of AIDS (DAIDS) Table for Grading the Severity of Adult and Pediatric Adverse Events, Corrected Version 2.1.

Participants recorded the occurrence of solicited symptoms on a diary card for 7 days after study product administration and reviewed the diary card with clinic staff at a follow up visit. Participants were counted once for each symptom at the worst severity if they indicated experiencing the symptom more than one time at any severity during the reporting period. The number reported for "Any Systemic Symptom" is the number of participants reporting any systemic symptom at the worst severity. Reactogenicity grading (Mild, Moderate, Severe) was done using the U.S. Department of Health and Human Services, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Division of AIDS (DAIDS) Table for Grading the Severity of Adult and Pediatric Adverse Events, Corrected Version 2.1.

Unsolicited adverse event (AE) data collection included AEs of all severities from the date of product administration through the Day 56 (8 weeks) post-product administration visit. After the Day 56 (8 weeks) post-product administration visit, only serious AEs (SAEs reported as a separate outcome and in the AE module) and new chronic medical conditions that require ongoing medical management (reported as a separate outcome) will be recorded through the last study visit. The relationship between a non-serious AE and the study product was assessed by the investigator based on clinical judgment and the definitions outlined in the protocol. A participant with multiple experiences of the same event is counted once using the event of worst severity.

Abnormal laboratory results recorded as unsolicited adverse events (AEs) are summarized. Safety lab parameters included hematology (hemoglobin, hematocrit, mean corpuscular volume (MCV), platelets, and neutrophil, lymphocyte, monocyte, eosinophil and basophil counts) and chemistry (alanine aminotransferase (ALT), aspartate aminotransferase (AST) and creatinine). Complete Blood Count (CBC) with differential and chemistry (ALT, AST and creatinine) results were collected at different timepoints throughout the study per the protocol's schedule of evaluations. Institutional laboratory normal ranges as well as the DAIDS Table for Grading the Severity of Adult and Pediatric Adverse Events, Corrected Version 2.1 were used.

Anti-AAV8 antibodies were analyzed by enzyme-linked immunosorbent assay (ELISA) using a vector-matched AAV8 capsid as the capture agent. Group geometric means and 95% confidence intervals (CIs) for the endpoint titers for the AAV8 ELISA assay are reported at baseline, week 12 for the peak response, and week 44 for durability. Values below the lower limit of detection (LOD) were imputed to the lower LOD (30) and values above the assay upper LOD were imputed to the upper LOD (21870).

In order to determine the optimal AAV8-VRC07 dose, participants must have attained a 50 mcg/mL VRC07 Serum Concentration. If no participants attained at least 50 mcg/mL VRC07 serum concentration, then the optimal AAV8-VRC07 dose cannot be determined.

For the pharmacokinetic (PK) primary outcome analysis, PK ELISA detected VRC07 serum antibodies in mcg/mL, using the VRC01 anti-idiotype Fab specific 5C9 monoclonal antibody (mAb). Only visits that had detectable PK ELISA concentrations for any participant are reported. Results are reported in group geometric mean mcg/mL concentrations with 95% CIs. The protocol specifies that a more sensitive assay can also be used; the more sensitive Singulex assay results are reported later in the secondary outcome measure. Values below the lower limit of detection (LOD) were imputed to the lower LOD (1 mcg/mL) with no 95% CI.

SAEs are recorded from receipt of study product through the last expected study visit at Year 5 (260 weeks). The relationship between a SAE and the study product is assessed by the investigator based on clinical judgment and the definitions outlined in the protocol. A participant with multiple experiences of the same event is counted once using the event of worst severity.

New chronic medical conditions are recorded from receipt of study product through the last expected study visit at Year 5 (260 weeks). The relationship between a new chronic medical condition and the study product is assessed by the investigator based on clinical judgment and the definitions outlined in the protocol. A participant with multiple experiences of the same event is counted once using the event of worst severity.

A three-tiered assay was used for ADA evaluation. The tier 1 screening assay measures specific and non-specific binding of serum proteins to VRC07 and the assay membrane. The tier 2 assay is a qualitative competition assay in which exogenously added VRC07 removes any VRC07-binding proteins from the serum prior to the binding assay. If the addition of the exogenous VRC07 results in a reduction of signal, the specificity of VRC07 binding is confirmed. The tier 3 assay is a qualitative assay that assesses the ability of VRC07-binding serum protein to prevent VRC07-mediated neutralization of an HIV pseudovirus in vitro. Only samples positive for a tier will be analyzed in subsequent tiers.

The clinical effects of pAAV8-VRC07 on cluster of differentiation 4 (CD4) cell count were assessed. CD4 Cell Count (cells/mL) shown as reported by the Clinical Center serology lab. Values are reported as group geometric means and 95% CIs.

The clinical effects of pAAV8-VRC07 on viral load were assessed. Viral Load is expressed in polymerase chain reaction (PCR) copies/mL, as reported by the Clinical Center serology lab. Values below the limit of quantification (\<20 copies/mL) or none detected were imputed to 10 copies/mL. Results are displayed as median(range).

The serum concentration of VRC07 at specified time intervals for 1 year after injection was determined, and if persistent, then every 6 months as long as there is detectable antibody in serum. The PK Singulex assay utilizes a microparticle-based immunoassay coupled with a fluorescent detection system to detect serum antibodies in the ng/mL range. Values below the limit of detection or none detected were set to 0.10 ng/mL; therefore, a value of 0.10 ng/mL means that the VRC07 concentration for that assay was below the limit of detection. Results are displayed as median(range).