Vaccination with prefusion-stabilized respiratory syncytial virus fusion protein induces genetically and antigenically diverse antibody responses.

An effective vaccine for respiratory syncytial virus (RSV) is an unrealized public health goal. A single dose of the prefusion-stabilized fusion (F) glycoprotein subunit vaccine (DS-Cav1) substantially increases serum-neutralizing activity in healthy adults. We sought to determine whether DS-Cav1 vaccination induces a repertoire mirroring the pre-existing diversity from natural infection or whether antibody lineages targeting specific epitopes predominate. We evaluated RSV F-specific B cell responses before and after vaccination in six participants using complementary B cell sequencing methodologies and identified 555 clonal lineages. DS-Cav1-induced lineages recognized the prefusion conformation of F (pre-F) and were genetically diverse. Expressed antibodies recognized all six antigenic sites on the pre-F trimer. We identified 34 public clonotypes, and structural analysis of two antibodies from a predominant clonotype revealed a common mode of recognition. Thus, vaccination with DS-Cav1 generates a diverse polyclonal response targeting the antigenic sites on pre-F, supporting the development and advanced testing of pre-F-based vaccines against RSV.

Subcutaneous Administration of a Monoclonal Antibody to Prevent Malaria.

BACKGROUND: Subcutaneous administration of the monoclonal antibody L9LS protected adults against controlled Plasmodium falciparum infection in a phase 1 trial. Whether a monoclonal antibody administered subcutaneously can protect children from P. falciparum infection in a region where this organism is endemic is unclear. METHODS: We conducted a phase 2 trial in Mali to assess the safety and efficacy of subcutaneous administration of L9LS in children 6 to 10 years of age over a 6-month malaria season. In part A of the trial, safety was assessed at three dose levels in adults, followed by assessment at two dose levels in children. In part B of the trial, children were randomly assigned, in a 1:1:1 ratio, to receive 150 mg of L9LS, 300 mg of L9LS, or placebo. The primary efficacy end point, assessed in a time-to-event analysis, was the first P. falciparum infection, as detected on blood smear performed at least every 2 weeks for 24 weeks. A secondary efficacy end point was the first episode of clinical malaria, as assessed in a time-to-event analysis. RESULTS: No safety concerns were identified in the dose-escalation part of the trial (part A). In part B, 225 children underwent randomization, with 75 children assigned to each group. No safety concerns were identified in part B. P. falciparum infection occurred in 36 participants (48%) in the 150-mg group, in 30 (40%) in the 300-mg group, and in 61 (81%) in the placebo group. The efficacy of L9LS against P. falciparum infection, as compared with placebo, was 66% (adjusted confidence interval [95% CI], 45 to 79) with the 150-mg dose and 70% (adjusted 95% CI, 50 to 82) with the 300-mg dose (P<0.001 for both comparisons). Efficacy against clinical malaria was 67% (adjusted 95% CI, 39 to 82) with the 150-mg dose and 77% (adjusted 95% CI, 55 to 89) with the 300-mg dose (P<0.001 for both comparisons). CONCLUSIONS: Subcutaneous administration of L9LS to children was protective against P. falciparum infection and clinical malaria over a period of 6 months. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT05304611.).

Low-Dose Subcutaneous or Intravenous Monoclonal Antibody to Prevent Malaria.

BACKGROUND: New approaches for the prevention and elimination of malaria, a leading cause of illness and death among infants and young children globally, are needed. METHODS: We conducted a phase 1 clinical trial to assess the safety and pharmacokinetics of L9LS, a next-generation antimalarial monoclonal antibody, and its protective efficacy against controlled human malaria infection in healthy adults who had never had malaria or received a vaccine for malaria. The participants received L9LS either intravenously or subcutaneously at a dose of 1 mg, 5 mg, or 20 mg per kilogram of body weight. Within 2 to 6 weeks after the administration of L9LS, both the participants who received L9LS and the control participants underwent controlled human malaria infection in which they were exposed to mosquitoes carrying Plasmodium falciparum (3D7 strain). RESULTS: No safety concerns were identified. L9LS had an estimated half-life of 56 days, and it had dose linearity, with the highest mean (±SD) maximum serum concentration (Cmax) of 914.2±146.5 µg per milliliter observed in participants who had received 20 mg per kilogram intravenously and the lowest mean Cmax of 41.5±4.7 µg per milliliter observed in those who had received 1 mg per kilogram intravenously; the mean Cmax was 164.8±31.1 in the participants who had received 5 mg per kilogram intravenously and 68.9±22.3 in those who had received 5 mg per kilogram subcutaneously. A total of 17 L9LS recipients and 6 control participants underwent controlled human malaria infection. Of the 17 participants who received a single dose of L9LS, 15 (88%) were protected after controlled human malaria infection. Parasitemia did not develop in any of the participants who received 5 or 20 mg per kilogram of intravenous L9LS. Parasitemia developed in 1 of 5 participants who received 1 mg per kilogram intravenously, 1 of 5 participants who received 5 mg per kilogram subcutaneously, and all 6 control participants through 21 days after the controlled human malaria infection. Protection conferred by L9LS was seen at serum concentrations as low as 9.2 µg per milliliter. CONCLUSIONS: In this small trial, L9LS administered intravenously or subcutaneously protected recipients against malaria after controlled infection, without evident safety concerns. (Funded by the National Institute of Allergy and Infectious Diseases; VRC 614 ClinicalTrials.gov number, NCT05019729.).

Safety, tolerability, and immunogenicity of the chimpanzee adenovirus type 3-vectored Marburg virus (cAd3-Marburg) vaccine in healthy adults in the USA: a first-in-human, phase 1, open-label, dose-escalation trial.

BACKGROUND: WHO has identified Marburg virus as an emerging virus requiring urgent vaccine research and development, particularly due to its recent emergence in Ghana. We report results from a first-in-human clinical trial evaluating a replication-deficient recombinant chimpanzee adenovirus type 3 (cAd3)-vectored vaccine encoding a wild-type Marburg virus Angola glycoprotein (cAd3-Marburg) in healthy adults. METHODS: We did a first-in-human, phase 1, open-label, dose-escalation trial of the cAd3-Marburg vaccine at the Walter Reed Army Institute of Research Clinical Trials Center in the USA. Healthy adults aged 18-50 years were assigned to receive a single intramuscular dose of cAd3-Marburg vaccine at either 1 × 1010 or 1 × 1011 particle units (pu). Primary safety endpoints included reactogenicity assessed for the first 7 days and all adverse events assessed for 28 days after vaccination. Secondary immunogenicity endpoints were assessment of binding antibody responses and T-cell responses against the Marburg virus glycoprotein insert, and assessment of neutralising antibody responses against the cAd3 vector 4 weeks after vaccination. This study is registered with ClinicalTrials.gov, NCT03475056. FINDINGS: Between Oct 9, 2018, and Jan 31, 2019, 40 healthy adults were enrolled and assigned to receive a single intramuscular dose of cAd3-Marburg vaccine at either 1 × 1010 pu (n=20) or 1 × 1011 pu (n=20). The cAd3-Marburg vaccine was safe, well tolerated, and immunogenic. All enrolled participants received cAd3-Marburg vaccine, with 37 (93%) participants completing follow-up visits; two (5%) participants moved from the area and one (3%) was lost to follow-up. No serious adverse events related to vaccination occurred. Mild to moderate reactogenicity was observed after vaccination, with symptoms of injection site pain and tenderness (27 [68%] of 40 participants), malaise (18 [45%] of 40 participants), headache (17 [43%] of 40 participants), and myalgia (14 [35%] of 40 participants) most commonly reported. Glycoprotein-specific antibodies were induced in 38 (95%) of 40 participants 4 weeks after vaccination, with geometric mean titres of 421 [95% CI 209-846] in the 1 × 1010 pu group and 545 [276-1078] in the 1 × 1011 pu group, and remained significantly elevated at 48 weeks compared with baseline titres (39 [95% CI 13-119] in the 1 ×1010 pu group and 27 [95-156] in the 1 ×1011 pu group; both p<0·0001). T-cell responses to the glycoprotein insert and neutralising responses against the cAd3 vector were also increased at 4 weeks after vaccination. INTERPRETATION: This first-in-human trial of this cAd3-Marburg vaccine showed the agent is safe and immunogenic, with a safety profile similar to previously tested cAd3-vectored filovirus vaccines. 95% of participants produced a glycoprotein-specific antibody response at 4 weeks after a single vaccination, which remained in 70% of participants at 48 weeks. These findings represent a crucial step in the development of a vaccine for emergency deployment against a re-emerging pathogen that has recently expanded its reach to new regions. FUNDING: National Institutes of Health.

A Monoclonal Antibody for Malaria Prevention.

BACKGROUND: Additional interventions are needed to reduce the morbidity and mortality caused by malaria. METHODS: We conducted a two-part, phase 1 clinical trial to assess the safety and pharmacokinetics of CIS43LS, an antimalarial monoclonal antibody with an extended half-life, and its efficacy against infection with Plasmodium falciparum. Part A of the trial assessed the safety, initial side-effect profile, and pharmacokinetics of CIS43LS in healthy adults who had never had malaria. Participants received CIS43LS subcutaneously or intravenously at one of three escalating dose levels. A subgroup of participants from Part A continued to Part B, and some received a second CIS43LS infusion. Additional participants were enrolled in Part B and received CIS43LS intravenously. To assess the protective efficacy of CIS43LS, some participants underwent controlled human malaria infection in which they were exposed to mosquitoes carrying P. falciparum sporozoites 4 to 36 weeks after administration of CIS43LS. RESULTS: A total of 25 participants received CIS43LS at a dose of 5 mg per kilogram of body weight, 20 mg per kilogram, or 40 mg per kilogram, and 4 of the 25 participants received a second dose (20 mg per kilogram regardless of initial dose). No safety concerns were identified. We observed dose-dependent increases in CIS43LS serum concentrations, with a half-life of 56 days. None of the 9 participants who received CIS43LS, as compared with 5 of 6 control participants who did not receive CIS43LS, had parasitemia according to polymerase-chain-reaction testing through 21 days after controlled human malaria infection. Two participants who received 40 mg per kilogram of CIS43LS and underwent controlled human malaria infection approximately 36 weeks later had no parasitemia, with serum concentrations of CIS43LS of 46 and 57 µg per milliliter at the time of controlled human malaria infection. CONCLUSIONS: Among adults who had never had malaria infection or vaccination, administration of the long-acting monoclonal antibody CIS43LS prevented malaria after controlled infection. (Funded by the National Institute of Allergy and Infectious Diseases; VRC 612 ClinicalTrials.gov number, NCT04206332.).

Safety and Immunogenicity of a Respiratory Syncytial Virus Fusion (F) Protein Nanoparticle Vaccine in Healthy Third-Trimester Pregnant Women and Their Infants.

BACKGROUND: Respiratory syncytial virus (RSV) is the leading cause of infant lower respiratory tract disease and hospitalization worldwide. METHODS: Safety and immunogenicity of RSV fusion (F) protein nanoparticle vaccine or placebo were evaluated in 50 healthy third-trimester pregnant women. Assessments included vaccine tolerability and safety in women and infants, and RSV-specific antibody measures in women before and after vaccination, at delivery and post partum. RESULTS: The vaccine was well tolerated; no meaningful differences in pregnancy or infant outcomes were observed between study groups. RSV-specific antibody levels increased significantly among vaccine recipients, including responses competitive with well-described monoclonal antibodies specific for multiple RSV neutralizing epitopes. No significant antibody increase was seen among placebo recipients, although a shallow upward trend across the RSV season was noted. Transplacental antibody transfer was 90%-120% across assays for infants of vaccinated women. Women with an interval of ≥30 days between vaccination and delivery demonstrated higher placental antibody transfer rates than women with an interval <30 days. Half-lives of RSV-specific antibodies in infants approximated 40 days. There was no evidence of severe RSV disease in infants of vaccinated mothers. CONCLUSIONS: Data from this phase 2 study support a maternal immunization strategy to protect infants from RSV disease. CLINICAL TRIALS REGISTRATION: NCT02247726.

Immunogenicity and safety of a respiratory syncytial virus fusion protein (RSV F) nanoparticle vaccine in older adults.

BACKGROUND: A preventative strategy for Respiratory Syncytial Virus (RSV) infection constitutes an under-recognized unmet medical need among older adults. Four formulations of a novel recombinant RSV F nanoparticle vaccine (60 or 90 µg RSV F protein, with or without aluminum phosphate adjuvant) administered concurrently with a licensed inactivated trivalent influenza vaccine (TIV) in older adult subjects were evaluated for safety and immunogenicity in this randomized, observer-blinded study. RESULTS: A total of 220 healthy males and females ≥ 60 years of age, without symptomatic cardiopulmonary disease, were vaccinated concurrently with TIV and RSV F vaccine or placebo. All vaccine formulations produced an acceptable safety profile, with no vaccine-related serious adverse events or evidence of systemic toxicity. Vaccine-induced immune responses were rapid, rising as early as 7 days post-vaccination; and were comparable in all formulations in terms of magnitude, with maximal levels attained within 28 (unadjuvanted) or 56 (adjuvanted) days post-vaccination. Peak anti-F protein IgG antibody levels rose 3.6- to 5.6-fold, with an adjuvant effect observed at the 60 µg dose, and a dose-effect observed between the unadjuvanted 60 and 90 µg regimens. The anti-F response persisted through 12 months post-vaccination. Palivizumab-competitive antibodies were below quantifiable levels (<33 µg/mL) at day 0. The rise of antibodies with specificity for Site II peptide, and the palivizumab-competitive binding activity, denoting antibodies binding at, or in proximity to, antigenic Site II on the F protein, closely paralleled the anti-F response. However, a larger proportion of antibodies in adjuvanted vaccine recipients bound to the Site II peptide at high avidity. Day 0 neutralizing antibodies were high in all subjects and rose 1.3- to 1.7-fold in response to vaccination. Importantly, the RSV F vaccine co-administered with TIV did not impact the serum hemagglutination inhibition antibody responses to a standard-dose TIV, and TIV did not impact the immune response to the RSV F vaccine. CONCLUSIONS: RSV F protein nanoparticle vaccine induced increases in measures of functional immunity to RSV in older adults and demonstrated an acceptable safety profile. Adjuvanted formulations provided additional immunogenicity benefit as compared to increasing antigen dose alone. This trial was registered with ClinicalTrials.gov number NCT01709019.

A Randomized, Blinded, Controlled, Dose-Ranging Study of a Respiratory Syncytial Virus Recombinant Fusion (F) Nanoparticle Vaccine in Healthy Women of Childbearing Age.

BACKGROUND: Respiratory syncytial virus (RSV) is a leading cause of infant morbidity and mortality. A recombinant RSV fusion protein nanoparticle vaccine (RSV F vaccine) candidate for maternal immunization was tested for safety and immunogenicity in women of childbearing age. METHODS: Three hundred thirty women (18-35 years) were randomized to receive 1 or 2 doses of RSV F vaccine (60 or 90 µg) with or without aluminum phosphate adjuvant, or placebo at days 0 and 28. Safety was evaluated over 180 days; immunogenicity and RSV infection rates were evaluated over 112 days. RESULTS: All vaccine formulations were well tolerated, without vaccine-related serious adverse events. Anti-F immunoglobulin G antibodies rose 6.5-15.6-fold, with significantly higher levels in 2-dose, adjuvanted regimens at day 56. Palivizumab-competitive antibody levels were undetectable at day 0 but increased up to 325 µg/mL at day 56. A 2.7- and 3.5-fold rise in RSV/A and RSV/B microneutralization antibodies were noted at day 56. Between days 56 and 112, 21% (12/56) of placebo recipients and 11% of vaccinees (26/244) showed evidence of a recent RSV infection (P = .04). CONCLUSIONS: The vaccine appeared safe, immunogenic, and reduced RSV infections. Further development as a vaccine for use in maternal immunization is warranted. CLINICAL TRIALS REGISTRATION: NCT01704365.

Phase 1 trial evaluating safety and pharmacokinetics of HIV-1 broadly neutralizing mAbs 10E8VLS and VRC07-523LS.

BACKGROUNDBroadly neutralizing monoclonal antibodies (bNAbs) represent a promising strategy for HIV-1 immunoprophylaxis and treatment. 10E8VLS and VRC07-523LS are bNAbs that target the highly conserved membrane-proximal external region (MPER) and the CD4-binding site of the HIV-1 viral envelope glycoprotein, respectively.METHODSIn this phase 1, open-label trial, we evaluated the safety and pharmacokinetics of 5 mg/kg 10E8VLS administered alone, or concurrently with 5 mg/kg VRC07-523LS, via s.c. injection to healthy non-HIV-infected individuals.RESULTSEight participants received either 10E8VLS alone (n = 6) or 10E8VLS and VRC07-523LS in combination (n = 2). Five (n = 5 of 8, 62.5%) participants who received 10E8VLS experienced moderate local reactogenicity, and 1 participant (n = 1/8, 12.5%) experienced severe local reactogenicity. Further trial enrollment was stopped, and no participant received repeat dosing. All local reactogenicity resolved without sequelae. 10E8VLS retained its neutralizing capacity, and no functional anti-drug antibodies were detected; however, a serum t1/2 of 8.1 days was shorter than expected. Therefore, the trial was voluntarily stopped per sponsor decision (Vaccine Research Center, National Institute of Allergy and Infectious Diseases [NIAID], NIH). Mechanistic studies performed to investigate the underlying reason for the reactogenicity suggest that multiple mechanisms may have contributed, including antibody aggregation and upregulation of local inflammatory markers.CONCLUSION10E8VLS resulted in unexpected reactogenicity and a shorter t1/2 in comparison with previously tested bNAbs. These studies may facilitate identification of nonreactogenic second-generation MPER-targeting bNAbs, which could be an effective strategy for HIV-1 immunoprophylaxis and treatment.TRIAL REGISTRATIONClinicaltrials.gov, accession no. NCT03565315.FUNDINGDivision of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH.

TRAF6 is a T cell-intrinsic negative regulator required for the maintenance of immune homeostasis.

TRAF6 has a key role in the regulation of innate immune responses by mediating signals from both TNF receptor and interleukin-1 receptor/Toll-like receptor superfamilies. Here we show that T cell-specific deletion of TRAF6 unexpectedly results in multiorgan inflammatory disease. TRAF6-deficient T cells exhibit hyperactivation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway compared with wild-type T cells and, as a result, become resistant to suppression by CD4+ CD25+ regulatory T cells. These data identify a previously unrecognized role for TRAF6 in the maintenance of peripheral tolerance, and suggest the presence of a T cell-intrinsic control mechanism to render responder T cells susceptible to tolerizing signals.

Safety, tolerability, and immunogenicity of the Ebola Sudan chimpanzee adenovirus vector vaccine (cAd3-EBO S) in healthy Ugandan adults: a phase 1, open-label, dose-escalation clinical trial.

BACKGROUND: Sudan Ebola virus can cause severe viral disease, with an average case fatality rate of 54%. A recent outbreak of Sudan Ebola virus in Uganda caused 55 deaths among 164 confirmed cases in the second half of 2022. Although vaccines and therapeutics specific for Zaire Ebola virus have been approved for use during outbreak situations, Sudan Ebola virus is an antigenically distinct virus with no approved vaccines available. METHODS: In this phase 1, open-label, dose-escalation trial we evaluated the safety, tolerability, and immunogenicity of a monovalent chimpanzee adenovirus 3 vaccine against Sudan Ebola virus (cAd3-EBO S) at Makerere University Walter Reed Project in Kampala, Uganda. Study participants were recruited from the Kampala metropolitan area using International Review Board-approved written and electronic media explaining the trial intervention. Healthy adults without previous receipt of Ebola, Marburg, or cAd3 vectored-vaccines were enrolled to receive cAd3-EBO S at either 1 × 1010 or 1 × 1011 particle units (PU) in a single intramuscular vaccination and were followed up for 48 weeks. Primary safety and tolerability endpoints were assessed in all vaccine recipients by reactogenicity for the first 7 days, adverse events for the first 28 days, and serious adverse events throughout the study. Secondary immunogenicity endpoints included evaluation of binding antibody and T-cell responses against the Sudan Ebola virus glycoprotein, and neutralising antibody responses against the cAd3 vector at 4 weeks after vaccination. This study is registered with ClinicalTrials.gov, NCT04041570, and is completed. FINDINGS: 40 healthy adults were enrolled between July 22 and Oct 1, 2019, with 20 receiving 1 × 1010 PU and 20 receiving 1 × 1011 PU of cAd3-EBO S. 38 (95%) participants completed all follow-up visits. The cAd3-EBO S vaccine was well tolerated with no severe adverse events. The most common reactogenicity symptoms were pain or tenderness at the injection site (34 [85%] of 40), fatigue (29 [73%] of 40), and headache (26 [65%] of 40), and were mild to moderate in severity. Positive responses for glycoprotein-specific binding antibodies were induced by 2 weeks in 31 (78%) participants, increased to 34 (85%) participants by 4 weeks, and persisted to 48 weeks in 31 (82%) participants. Most participants developed glycoprotein-specific T-cell responses (20 [59%, 95% CI 41-75] of 34; six participants were removed from the T cell analysis after failing quality control parameters) by 4 weeks after vaccination, and neutralising titres against the cAd3 vector were also increased from baseline (90% inhibitory concentration of 47, 95% CI 30-73) to 4 weeks after vaccination (196, 125-308). INTERPRETATION: The cAd3-EBO S vaccine was safe at both doses, rapidly inducing immune responses in most participants after a single injection. The rapid onset and durability of the vaccine-induced antibodies make this vaccine a strong candidate for emergency deployment in Sudan Ebola virus outbreaks. FUNDING: National Institutes of Health via interagency agreement with Walter Reed Army Institute of Research.

Low-dose intravenous and subcutaneous CIS43LS monoclonal antibody for protection against malaria (VRC 612 Part C): a phase 1, adaptive trial.

BACKGROUND: Human monoclonal antibodies might offer an important new approach to reduce malaria morbidity and mortality. In the first two parts of a three-part clinical trial, the antimalarial monoclonal antibody CIS43LS conferred high protection against parasitaemia at doses of 20 mg/kg or 40 mg/kg administered intravenously followed by controlled human malaria infection. The ability of CIS43LS to confer protection at lower doses or by the subcutaneous route is unknown. We aimed to provide data on the safety and optimisation of dose and route for the human antimalaria monoclonal antibody CIS43LS. METHODS: VRC 612 Part C was the third part of a three-part, first-in-human, phase 1, adaptive trial, conducted at the University of Maryland, Baltimore Center for Vaccine Development and Global Health, Baltimore, MD, USA. We enrolled adults aged 18-50 years with no previous malaria vaccinations or infections, in a sequential, dose-escalating manner. Eligible participants received the monoclonal antibody CIS43LS in a single, open-label dose of 1 mg/kg, 5 mg/kg, or 10 mg/kg intravenously, or 5 mg/kg or 10 mg/kg subcutaneously. Participants underwent controlled human malaria infection by the bites of five mosquitoes infected with Plasmodium falciparum 3D7 strain approximately 8 weeks after their monoclonal antibody inoculation. Six additional control participants who did not receive CIS43LS underwent controlled human malaria infection simultaneously. Participants were followed-up daily on days 7-18 and day 21, with qualitative PCR used for P falciparum detection. Participants who tested positive for P falciparum were treated with atovaquone-proguanil and those who remained negative were treated at day 21. Participants were followed-up until 24 weeks after dosing. The primary outcome was safety and tolerability of CIS43LS at each dose level, assessed in the as-treated population. Secondary outcomes included protective efficacy of CIS43LS after controlled human malaria infection. This trial is now complete and is registered with ClinicalTrials.gov, NCT04206332. FINDINGS: Between Sept 1, 2021, and Oct 29, 2021, 47 people were assessed for eligibility and 31 were enrolled (one subsequently withdrew and was replaced) and assigned to receive doses of 1 mg/kg (n=7), 5 mg/kg (n=4), and 10 mg/kg (n=3) intravenously and 5 mg/kg (n=4) and 10 mg/kg (n=4) subcutaneously, or to the control group (n=8). CIS43LS administration was safe and well tolerated; no serious adverse events occurred. CIS43LS protected 18 (82%) of 22 participants who received a dose. No participants developed parasitaemia following dosing at 5 mg/kg intravenously or subcutaneously, or at 10 mg/kg intravenously or subcutaneously. All six control participants and four of seven participants dosed at 1 mg/kg intravenously developed parasitaemia after controlled human malaria infection. INTERPRETATION: CIS43LS was safe and well tolerated, and conferred protection against P falciparum at low doses and by the subcutaneous route, providing evidence that this approach might be useful to prevent malaria across several clinical use cases. FUNDING: National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Safety and immunogenicity of an HIV-1 prefusion-stabilized envelope trimer (Trimer 4571) vaccine in healthy adults: A first-in-human open-label, randomized, dose-escalation, phase 1 clinical trial.

Background: Advances in therapeutic drugs have increased life-expectancies for HIV-infected individuals, but the need for an effective vaccine remains. We assessed safety and immunogenicity of HIV-1 vaccine, Trimer 4571 (BG505 DS-SOSIP.664) adjuvanted with aluminum hydroxide (alum), in HIV-negative adults. Methods: We conducted a phase I, randomized, open-label, dose-escalation trial at the National Institutes of Health Clinical Center in Bethesda, MD, USA. Eligible participants were HIV-negative, healthy adults between 18-50 years. Participants were randomized 1:1 to receive Trimer 4571 adjuvanted with 500 mcg alum by either the subcutaneous (SC) or intramuscular (IM) route at weeks 0, 8, and 20 in escalating doses of 100 mcg or 500 mcg. The primary objectives were to evaluate the safety and tolerability of Trimer 4571 with a secondary objective of evaluating vaccine-induced antibody responses. The primary and safety endpoints were evaluated in all participants who received at least one dose of Trimer 4571. Trial results were summarized using descriptive statistics. This trial is registered at ClinicalTrials.gov, NCT03783130. Findings: Between March 7 and September 11, 2019, 16 HIV-negative participants were enrolled, including six (38%) males and ten (62%) females. All participants received three doses of Trimer 4571. Solicited reactogenicity was mild to moderate in severity, with one isolated instance of severe injection site redness (6%) following a third 500 mcg SC administration. The most commonly reported solicited symptoms included mild injection site tenderness in 14 (88%) and mild myalgia in six (38%) participants. The most frequent unsolicited adverse event attributed to vaccination was mild injection site pruritus in six (38%) participants. Vaccine-induced seropositivity occurred in seven (44%) participants and resolved in all but one (6%). No serious adverse events occurred. Trimer 4571-specific binding antibodies were detected in all groups two weeks after regimen completion, primarily focused on the glycan-free trimer base. Neutralizing antibody activity was limited to the 500 mcg dose groups. Interpretation: Trimer 4571 was safe, well tolerated, and immunogenic in this first-in-human trial. While this phase 1 trial is limited in size, our results inform and support further evaluation of prefusion-stabilized HIV-1 envelope trimers as a component of vaccine design strategies to generate broadly neutralizing antibodies against HIV-1. Funding: Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Safety, tolerability, and immunogenicity of the respiratory syncytial virus prefusion F subunit vaccine DS-Cav1: a phase 1, randomised, open-label, dose-escalation clinical trial.

BACKGROUND: Multiple active vaccination approaches have proven ineffective in reducing the substantial morbidity and mortality caused by respiratory syncytial virus (RSV) in infants and older adults (aged ≥65 years). A vaccine conferring a substantial and sustainable boost in neutralising activity is required to protect against severe RSV disease. To that end, we evaluated the safety and immunogenicity of DS-Cav1, a prefusion F subunit vaccine. METHODS: In this randomised, open-label, phase 1 clinical trial, the stabilised prefusion F vaccine DS-Cav1 was evaluated for dose, safety, tolerability, and immunogenicity in healthy adults aged 18-50 years at a single US site. Participants were assigned to receive escalating doses of either 50 µg, 150 µg, or 500 µg DS-Cav1 at weeks 0 and 12, and were randomly allocated in a 1:1 ratio within each dose group to receive the vaccine with or without aluminium hydroxide (AlOH) adjuvant. After 71 participants had been randomised, the protocol was amended to allow some participants to receive a single vaccination at week 0. The primary objectives evaluated the safety and tolerability at every dose within 28 days following each injection. Neutralising activity and RSV F-binding antibodies were evaluated from week 0 to week 44 as secondary and exploratory objectives. Safety was assessed in all participants who received at least one vaccine dose; secondary and exploratory immunogenicity analysis included all participants with available data at a given visit. The trial is registered with ClinicalTrials.gov, NCT03049488, and is complete and no longer recruiting. FINDINGS: Between Feb 21, 2017, and Nov 29, 2018, 244 participants were screened for eligibility and 95 were enrolled to receive DS-Cav1 at the 50 µg (n=30, of which n=15 with AlOH), 150 µg (n=35, of which n=15 with AlOH), or 500 µg (n=30, of which n=15 with AlOH) doses. DS-Cav1 was safe and well tolerated and no serious vaccine-associated adverse events deemed related to the vaccine were identified. DS-Cav1 vaccination elicited robust neutralising activity and binding antibodies by 4 weeks after a single vaccination (p<0·0001 for F-binding and neutralising antibodies). In analyses of exploratory endpoints at week 44, pre-F-binding IgG and neutralising activity were significantly increased compared with baseline in all groups. At week 44, RSV A neutralising activity was 3·1 fold above baseline in the 50 µg group, 3·8 fold in the 150 µg group, and 4·5 fold in the 500 µg group (p<0·0001). RSV B neutralising activity was 2·8 fold above baseline in the 50 µg group, 3·4 fold in the 150 µg group, and 3·7 fold in the 500 µg group (p<0·0001). Pre-F-binding IgG remained significantly 3·2 fold above baseline in the 50 µg group, 3·4 fold in the 150 µg group, and 4·0 fold in the 500 µg group (p<0·0001). Pre-F-binding serum IgA remained 4·1 fold above baseline in the 50 µg group, 4·3 fold in the 150 µg group, and 4·8 fold in the 500 µg group (p<0·0001). Although a higher vaccine dose or second immunisation elicited a transient advantage compared with lower doses or a single immunisation, neither significantly impacted long-term neutralisation. There was no long-term effect of dose, number of vaccinations, or adjuvant on neutralising activity. INTERPRETATION: In this phase 1 study, DS-Cav1 vaccination was safe and well tolerated. DS-Cav1 vaccination elicited a robust boost in RSV F-specific antibodies and neutralising activity that was sustained above baseline for at least 44 weeks. A single low-dose of pre-F immunisation of antigen-experienced individuals might confer protection that extends throughout an entire RSV season. FUNDING: The National Institutes of Allergy and Infectious Diseases.

A proof of concept for structure-based vaccine design targeting RSV in humans.

Technologies that define the atomic-level structure of neutralization-sensitive epitopes on viral surface proteins are transforming vaccinology and guiding new vaccine development approaches. Previously, iterative rounds of protein engineering were performed to preserve the prefusion conformation of the respiratory syncytial virus (RSV) fusion (F) glycoprotein, resulting in a stabilized subunit vaccine candidate (DS-Cav1), which showed promising results in mice and macaques. Here, phase I human immunogenicity data reveal a more than 10-fold boost in neutralizing activity in serum from antibodies targeting prefusion-specific surfaces of RSV F. These findings represent a clinical proof of concept for structure-based vaccine design, suggest that development of a successful RSV vaccine will be feasible, and portend an era of precision vaccinology.

A Phase 2 randomized, observer-blind, placebo-controlled, dose-ranging trial of aluminum-adjuvanted respiratory syncytial virus F particle vaccine formulations in healthy women of childbearing age.

OBJECTIVE: Respiratory syncytial virus (RSV) causes significant morbidity and mortality in infants. We are developing an RSV fusion (F) protein nanoparticle vaccine for immunization of third trimester pregnant women to passively protect infants through transfer of RSV-specific maternal antibodies. The present trial was performed to assess the immunogenicity and safety of several formulations of RSV F vaccine in 1-dose or 2-dose schedules. METHODS: Placebo, or vaccine with 60µg or 120µg RSV F protein and 0.2, 0.4, or 0.8mg aluminum, were administered intramuscularly on Days 0 and 28 to healthy women 18-35years old. Immunogenicity was assessed from Days 0 through 91 based on anti-F IgG and palivizumab-competitive antibody (PCA) by ELISA, and RSV A and B neutralizing antibodies by microneutralization (MN) assay. Solicited adverse events were collected through Day 7 and unsolicited adverse events through Day 91. RESULTS: All formulations were well-tolerated, with no treatment-related serious adverse events. Anti-F IgG and PCA responses were correlated and increased after both doses, while MN increased significantly only after the first dose, then plateaued. The timeliest and most robust antibody responses followed one dose of 120µg RSV F protein and 0.4mg aluminum, but persistence through 91days was modestly (∼25%) superior following two doses of 60µg RSV F protein and 0.8mg aluminum. Western blot analysis showed RSV infections in active vaccinees were reduced by 52% overall (p=0.009 overall) over the Day 0 through 90 period. CONCLUSIONS: RSV F nanoparticle vaccine formulations were well tolerated and immunogenic. The optimal combination of convenience and rapid response for immunization in the third trimester occurred with 120µg RSV F and 0.4mg aluminum, which achieved peak immune responses in 14days and sufficient persistence through 91days to allow for passive transfer of IgG antibodies to the fetus. NCT01960686.

Modeling maternal fetal RSV F vaccine induced antibody transfer in guinea pigs.

BACKGROUND: Protection of newborns and young infants against RSV disease via maternal immunization mediated by transplacental transfer of antibodies is under evaluation in third-trimester pregnant women with the RSV recombinant F nanoparticle vaccine (RSV F vaccine). Since the hemichorial placental architecture in guinea pigs and humans is similar, the guinea pig model was employed to assess RSV F vaccine immunogenicity in pregnant sows and to compare RSV-specific maternal antibody levels in their pups. METHODS: Thirty (30) presumptive pregnant guinea pigs were immunized on gestational day 25 and 46 with placebo (PBS), 30µg RSV F, or 30µg RSV F+400µg aluminum phosphate. Sera at delivery/birth (sows/pups) and 15 and 30 days post-partum (pups) were analyzed for the presence of anti-F IgG, palivizumab-competitive antibody (PCA) and RSV/A microneutralization (MN). RESULTS: The rates of pregnancy and stillbirth were similar between controls and vaccinees. The vaccine induced high levels of anti-F IgG, PCA and MN in sows, with the highest levels observed in adjuvanted vaccinees. Placental transfer to pups was proportional to the maternal antibody levels, with concentration effects observed for all immune measures. CONCLUSIONS: The RSV F vaccine was safe and immunogenic in pregnant guinea pigs and supported robust transplacental antibody transfer to their pups. Relative concentration of antibodies in the pups was observed even in the presence of high levels of maternal antibody. Guinea pigs may be an important safety and immunogenicity model for preclinical assessment of candidate vaccines for maternal immunization.

Safety and immunogenicity of a Sf9 insect cell-derived respiratory syncytial virus fusion protein nanoparticle vaccine.

OBJECTIVE: We performed a Phase 1 randomized, observer-blinded, placebo-controlled trial to evaluate the safety and immunogenicity of a recombinant respiratory syncytial virus (RSV) fusion (F) protein nanoparticle vaccine. METHODS: Six formulations with (5, 15, 30 and 60 µg) and without (30 and 60 µg) aluminum phosphate (AdjuPhos) were administered intramuscularly on day 0 and 30 in a dose escalating fashion to healthy adults 18-49 years of age. Solicited and unsolicited events were collected through day 210. Immunogenicity measures taken at day 0, 30 and 60 included RSV A and B microneutralization, anti-F IgG, antigenic site II peptide and palivizumab competitive antibodies. RESULTS: The vaccine was well-tolerated, with no evident dose-related toxicity or attributable SAEs. At day 60 both RSV A and B microneutralization was significantly increased in vaccinees versus placebo. Across all vaccinees there was a 7- to 19-fold increase in the anti-F IgG and a 7- to 24-fold increase in the antigenic site II binding and palivizumab competitive antibodies. CONCLUSIONS: The RSV F nanoparticle vaccine candidate was well tolerated without dose-related increases in adverse events. Measures of immunity indicate that neutralization, anti-RSV F IgG titers and palivizumab competing antibodies were induced at levels that have been associated with decreased risk of hospitalization. NCT01290419.

Safety and immunogenicity of a virus-like particle pandemic influenza A (H1N1) 2009 vaccine in a blinded, randomized, placebo-controlled trial of adults in Mexico.

Virus-like particles (VLPs) can be rapidly developed from influenza virus genetic sequences in order to supply vaccine after the onset of a pandemic. The safety and immunogenicity of one or two doses of a recombinant A (H1N1) 2009 influenza VLP vaccine was evaluated in a two-stage, Phase 2, randomized, double-blind, placebo-controlled study conducted in 4563 healthy adults, 18-64 years of age, during the H1N1 2009 pandemic in Mexico. In Part A, 1013 subjects were randomized into four treatment groups (5 µg, 15 µg, or 45 µg hemagglutinin [HA] VLP vaccine or placebo) and vaccinated 21 days apart, with sera collected on Days 1, 14 and 36 for hemagglutination inhibition (HAI) testing. After review of safety and immunogenicity data from Part A, additional subjects were immunized with a single dose of 15 µg VLP vaccine (N=2537) or placebo (N=1011) and assessed for safety in Part B. Results showed the H1N1 2009 VLP vaccine was safe and well-tolerated. Systemic solicited events were similar between placebo and VLP vaccinated groups with no vaccine-related serious adverse events. Dose response trends for solicited local adverse events were observed, with higher incidences of local pain, swelling, tenderness, and redness reported in the higher VLP dose groups (15 µg and 45 µg) compared to the placebo and 5 µg VLP groups following both vaccinations. Although the majority of local AEs were mild in severity, a dose trend in events of moderate or greater severity was also noted for these solicited events. The VLP vaccine groups demonstrated robust HAI immune responses after a single vaccination, with high rates of seroprotection (≥ 40 HAI titer) in 82-92% of all subjects and in 64-85% of subjects who were seronegative at the time of immunization. HAI geometric mean titers (GMTs), geometric mean ratios (GMRs) and seroconversion rates were also all statistically higher in the VLP groups compared to placebo for both post-baseline time points. Based on these data, additional clinical trials are in development to evaluate influenza vaccine candidate antigens manufactured using Spodoptera frugiperda (Sf9)/baculovirus-based VLP technology.

Disparity in IL-12 release in dendritic cells and macrophages in response to Mycobacterium tuberculosis is due to use of distinct TLRs.

The control of IL-12 production from dendritic cells (DCs) and macrophages in response to Mycobacterium tuberculosis (Mtb) is not well understood. The objective of this study was to pursue the mechanism underlying our previous report that in response to Mtb infection, DCs release abundant IL-12, whereas secretion is limited in macrophages. An initial comparison of IL-12p35 and IL-12p40 gene induction showed that p35 transcription is similar in murine bone marrow-derived DCs and macrophages, but a rapid and enhanced IL-12p40 transcription occurs only in DCs. Consistent with the p40 gene transcription profile, Mtb-induced remodeling at nucleosome 1 of the p40 promoter also occurs rapidly and extensively in DCs in comparison to macrophages. Removal of IL-10 or addition of IFNgamma enhances macrophage IL-12 release to Mtb, but without affecting the kinetics of remodeling at the macrophage p40 promoter. Furthermore, we show that Mtb-induced remodeling at the p40 promoter and IL-12 release in DCs is TLR9 dependent, and in contrast, TLR2 dependent, in macrophages. Data are also presented to demonstrate that a TLR9 agonist induces quantitatively more extensive remodeling at the IL-12p40 promoter and larger IL-12 release in comparison to a TLR2 agonist. Collectively, these findings suggest that DCs and macrophages handle Mtb differently resulting in only DCs being able to engage the more efficient TLR9 pathway for IL-12 gene induction. Our results also imply that TLR2 signaling is not a good inducer of IL-12, supporting the increasingly strong paradigm that TLR2 favors Th2 responses.