Safety and Immunogenicity of a ChAd155-Vectored Respiratory Syncytial Virus (RSV) Vaccine in Healthy RSV-Seropositive Children 12-23 Months of Age.

BACKGROUND: Safe and effective respiratory syncytial virus (RSV) vaccines remain elusive. This was a phase I/II trial (NCT02927873) of ChAd155-RSV, an investigational chimpanzee adenovirus-RSV vaccine expressing 3 proteins (fusion, nucleoprotein, and M2-1), administered to 12-23-month-old RSV-seropositive children followed up for 2 years after vaccination. METHODS: Children were randomized to receive 2 doses of ChAd155-RSV or placebo (at a 1:1 ratio) (days 1 and 31). Doses escalated from 0.5 × 1010 (low dose [LD]) to 1.5 × 1010 (medium dose [MD]) to 5 × 1010 (high dose [HD]) viral particles after safety assessment. Study end points included anti-RSV-A neutralizing antibody (Nab) titers through year 1 and safety through year 2. RESULTS: Eighty-two participants were vaccinated, including 11, 14, and 18 in the RSV-LD, RSV-MD, and RSV-HD groups, respectively, and 39 in the placebo groups. Solicited adverse events were similar across groups, except for fever (more frequent with RSV-HD). Most fevers were mild (≤38.5°C). No vaccine-related serious adverse events or RSV-related hospitalizations were reported. There was a dose-dependent increase in RSV-A Nab titers in all groups after dose 1, without further increase after dose 2. RSV-A Nab titers remained higher than prevaccination levels at year 1. CONCLUSIONS: Three ChAd155-RSV dosages were found to be well tolerated. A dose-dependent immune response was observed after dose 1, with no observed booster effect after dose 2. Further investigation of ChAd155-RSV in RSV-seronegative children is warranted. CLINICAL TRIALS REGISTRATION: NCT02927873.

Respiratory syncytial virus (RSV) is among the main causes of bronchiolitis and pneumonia regularly leading to hospitalization in children. A safe and effective vaccine to prevent RSV infection in this age group has not yet been found, despite great efforts over several decades. This study tested a new candidate RSV vaccine, expressing 3 important pieces of the virus, in toddlers who already had a previous RSV infection. The vaccine was generally well tolerated. Vaccination triggered antibodies against RSV that were able to block the virus in laboratory tests and that persisted for 1 year.

First-in-Human Randomized Study to Assess the Safety and Immunogenicity of an Investigational Respiratory Syncytial Virus (RSV) Vaccine Based on Chimpanzee-Adenovirus-155 Viral Vector-Expressing RSV Fusion, Nucleocapsid, and Antitermination Viral Proteins in Healthy Adults.

BACKGROUND: Respiratory syncytial virus (RSV) disease is a major cause of infant morbidity and mortality. This Phase I, randomized, observer-blind, placebo- and active-controlled study evaluated an investigational vaccine against RSV (ChAd155-RSV) using the viral vector chimpanzee-adenovirus-155, encoding RSV fusion (F), nucleocapsid, and transcription antitermination proteins. METHODS: Healthy 18-45-year-old adults received ChAd155-RSV, a placebo, or an active control (Bexsero) at Days (D) 0 and 30. An escalation from a low dose (5 × 109 viral particles) to a high dose (5 × 1010 viral particles) occurred after the first 16 participants. Endpoints were solicited/unsolicited and serious adverse events (SAEs), biochemical/hematological parameters, cell-mediated immunogenicity by enzyme-linked immunospot, functional neutralizing antibodies, anti RSV-F immunoglobin (Ig) G, and ChAd155 neutralizing antibodies. RESULTS: There were 7 participants who received the ChAd155-RSV low dose, 31 who received the ChAd155-RSV high dose, 19 who received the placebo, and 15 who received the active control. No dose-related toxicity or attributable SAEs at the 1-year follow-up were observed. The RSV-A neutralizing antibodies geometric mean titer ratios (post/pre-immunization) following a high dose were 2.6 (D30) and 2.3 (D60). The ratio of the fold-rise (D0 to D30) in anti-F IgG over the fold-rise in RSV-A-neutralizing antibodies was 1.01. At D7 after the high dose of the study vaccine, the median frequencies of circulating B-cells secreting anti-F antibodies were 133.3/106 (IgG) and 16.7/106 (IgA) in peripheral blood mononuclear cells (PBMCs). The median frequency of RSV-F-specific interferon γ-secreting T-cells after a ChAd155-RSV high dose was 108.3/106 PBMCs at D30, with no increase after the second dose. CONCLUSIONS: In adults previously naturally exposed to RSV, ChAd155-RSV generated increases in specific humoral and cellular immune responses without raising significant safety concerns. CLINICAL TRIALS REGISTRATION: NCT02491463.

Long-term Cross-reactivity Against Nonvaccine Human Papillomavirus Types 31 and 45 After 2- or 3-Dose Schedules of the AS04-Adjuvanted Human HPV-16/18 Vaccine.

This analysis focused on long-term cross-reactive immunogenicity against nonvaccine human papillomavirus (HPV) types 31 and 45 following 2 doses of AS04-adjuvanted HPV-16/18 vaccine in girls aged 9-14 years or following 3 doses in women aged 15-25 years, for up to 3 years (HPV-070 study) and up to 5 years (HPV-048 study) after the first vaccination. Both schedules elicited antibodies against HPV-31 and HPV-45 up to 5 years after first dose. The antibody concentration was similar in young girls as compared to women. Specific CD4+ T-cell and B-cell responses to HPV-31 and HPV-45 at month 36 were similar across groups. Clinical trials registration: NCT01381575 and NCT00541970.

Impact of adjuvants on CD4(+) T cell and B cell responses to a protein antigen vaccine: Results from a phase II, randomized, multicenter trial.

Immunogenicity and safety of different adjuvants combined with a model antigen (HBsAg) were compared. Healthy HBV-naïve adults were randomized to receive HBs adjuvanted with alum or Adjuvant Systems AS01B, AS01E, AS03A or AS04 at Days 0 and 30. Different frequencies of HBs-specific CD4+ T cells 14days post dose 2 but similar polyfunctionality profiles were induced by the different adjuvants with frequencies significantly higher in the AS01B and AS01E groups than in the other groups. Antibody concentrations 30days post-dose 2 were significantly higher in AS01B, AS01E and AS03A than in other groups. Limited correlations were observed between HBs-specific CD4+ T cell and antibody responses. Injection site pain was the most common solicited local symptom and was more frequent in AS groups than in alum group. Different adjuvants formulated with the same antigen induced different adaptive immune responses and reactogenicity patterns in healthy naïve adults. The results summary for this study (GSK study number 112115 - NCT# NCT00805389) is available on the GSK Clinical Study Register and can be accessed at www.gsk-clinicalstudyregister.com.

Superior antigen-specific CD4+ T-cell response with AS03-adjuvantation of a trivalent influenza vaccine in a randomised trial of adults aged 65 and older.

BACKGROUND: The effectiveness of trivalent influenza vaccines may be reduced in older versus younger adults because of age-related immunosenescence. The use of an adjuvant in such a vaccine is one strategy that may combat immunosenescence, potentially by bolstering T-cell mediated responses. METHODS: This observer-blind study, conducted in the United States (US) and Spain during the 2008-2009 influenza season, evaluated the effect of Adjuvant System AS03 on specific T-cell responses to a seasonal trivalent influenza vaccine (TIV) in ≥65 year-old adults.Medically-stable adults aged ≥65 years were randomly allocated to receive a single dose of AS03-adjuvanted TIV (TIV/AS03) or TIV. Healthy adults aged 18-40 years received only TIV. Blood samples were collected on Day 0, Day 21, Day 42 and Day 180. Influenza-specific CD4+ T cells, defined by the induction of the immune markers CD40L, IL-2, IFN-γ, or TNF-α, were measured in ex vivo cultures of antigen-stimulated peripheral blood mononuclear cells. RESULTS: A total of 192 adults were vaccinated: sixty nine and seventy three ≥65 year olds received TIV/AS03 and TIV, respectively; and fifty 18 - 40 year olds received TIV. In the ≥65 year-old group on Day 21, the frequency of CD4+ T cells specific to the three vaccine strains was superior in the TIV/AS03 recipients to the frequency in TIV (p < 0.001). On Days 42 and 180, the adjusted-geometric mean specific CD4+ T-cell frequencies were also higher in the TIV/AS03 recipients than in the TIV recipients (p < 0.001). Furthermore, the adjusted-geometric mean specific CD4+ T-cell frequencies were higher in the ≥65 year-old recipients of TIV/AS03 than in the18 - 40 year old recipients of TIV on Days 21 (p = 0.006) and 42 (p = 0.011). CONCLUSION: This positive effect of AS03 Adjuvant System on the CD4+ T-cell response to influenza vaccine strains in older adults could confer benefit in protection against clinical influenza disease in this population. TRIAL REGISTRATION: (Clinicaltrials.gov.). NCT00765076.

Antigen-specific IL-2 secretion correlates with NK cell responses after immunization of Tanzanian children with the RTS,S/AS01 malaria vaccine.

RTS,S/AS01, a vaccine targeting pre-erythrocytic stages of Plasmodium falciparum, is undergoing clinical trials. We report an analysis of cellular immune response to component Ags of RTS,S-hepatitis B surface Ag (HBs) and P. falciparum circumsporozoite (CS) protein-among Tanzanian children in a phase IIb RTS,S/AS01(E) trial. RTS,S/AS01 (E) vaccinees make stronger T cell IFN-γ, CD69, and CD25 responses to HBs peptides than do controls, indicating that RTS,S boosts pre-existing HBs responses. T cell CD69 and CD25 responses to CS and CS-specific secreted IL-2 were augmented by RTS,S vaccination. Importantly, more than 50% of peptide-induced IFN-γ(+) lymphocytes were NK cells, and the magnitude of the NK cell CD69 response to HBs peptides correlated with secreted IL-2 concentration. CD69 and CD25 expression and IL-2 secretion may represent sensitive markers of RTS,S-induced, CS-specific T cells. The potential for T cell-derived IL-2 to augment NK cell activation in RTS,S-vaccinated individuals, and the relevance of this for protection, needs to be explored further.

Induction and regulation of T-cell immunity by the novel tuberculosis vaccine M72/AS01 in South African adults.

RATIONALE: Tuberculosis (TB) is a major cause of morbidity and mortality worldwide, thus there is an urgent need for novel TB vaccines. OBJECTIVES: We investigated a novel TB vaccine candidate, M72/AS01, in a phase IIa trial of bacille Calmette-Guérin-vaccinated, HIV-uninfected, and Mycobacterium tuberculosis (Mtb)-infected and -uninfected adults in South Africa. METHODS: Two doses of M72/AS01 were administered to healthy adults, with and without latent Mtb infection. Participants were monitored for 7 months after the first dose; cytokine production profiles, cell cycling, and regulatory phenotypes of vaccine-induced T cells were measured by flow cytometry. MEASUREMENTS AND MAIN RESULTS: The vaccine had a clinically acceptable safety profile, and induced robust, long-lived M72-specific T-cell and antibody responses. M72-specific CD4 T cells produced multiple combinations of Th1 cytokines. Analysis of T-cell Ki67 expression showed that most vaccination-induced T cells did not express Th1 cytokines or IL-17; these cytokine-negative Ki67(+) T cells included subsets of CD4 T cells with regulatory phenotypes. PD-1, a negative regulator of activated T cells, was transiently expressed on M72-specific CD4 T cells after vaccination. Specific T-cell subsets were present at significantly higher frequencies after vaccination of Mtb-infected versus -uninfected participants. CONCLUSIONS: M72/AS01 is clinically well tolerated in Mtb-infected and -uninfected adults, induces high frequencies of multifunctional T cells, and boosts distinct T-cell responses primed by natural Mtb infection. Moreover, these results provide important novel insights into how this immunity may be appropriately regulated after novel TB vaccination of Mtb-infected and -uninfected individuals.Clinical trial registered with www.clinicaltrials.gov (NCT 00600782).

A randomized, controlled dose-finding Phase II study of the M72/AS01 candidate tuberculosis vaccine in healthy PPD-positive adults.

PURPOSE: In this dose-finding Phase II study (NCT00621322), we evaluated the safety and immunogenicity of different formulations of the candidate tuberculosis vaccine containing the M72 antigen (10/20/40 µg doses) and the liposome-based AS01 Adjuvant System. We aimed to select the lowest-dose combination of M72 and AS01 that was clinically well tolerated with immunogenicity comparable to that of the previously tested M72/AS01B (40 µg) candidate vaccine. METHODS: Healthy PPD-positive (induration 3-10 mm) adults (18-45 years) in The Philippines were randomized (4:4:4:4:1:1) to receive 2 injections, 1 month apart, of M72/AS01B (40 µg), M72/AS01E (10 µg), M72/AS01E (20 µg), M72/AS02D (10 µg), M72/Saline (40 µg) or AS01B alone, and were followed up for 6 months. AS01E and AS02D contain half the quantities of the immunostimulants present in AS01B. AS02D is an oil-in-water emulsion. Vaccine selection was based on the CD4(+) T-cell responses at 1 month post vaccination. RESULTS: All formulations had a clinically acceptable safety profile with no vaccine-related serious adverse events reported. Two vaccinations of each adjuvanted M72 vaccine induced M72-specific CD4(+) T-cell and humoral responses persisting at 6 months post vaccination. No responses were observed with AS01B alone. One month post second vaccination, CD4(+) T-cell responses induced by each of the three M72/AS01 vaccine formulations were of comparable magnitudes, and all were significantly higher than those induced by M72/AS02D (10 µg) and M72/Saline. CONCLUSIONS: The formulation with the lowest antigen and adjuvant dose, M72/AS01E (10 µg), fulfilled our pre-defined selection criteria and has been selected for further clinical development.

Characterization of B-cell and T-cell responses to a tetravalent dengue purified inactivated vaccine in healthy adults.

The increasing global impact of dengue underscores the need for a dengue virus (DENV) vaccine. We assessed B-cell and T-cell responses following vaccination with four formulations of a tetravalent dengue purified inactivated vaccine (DPIV) in dengue-primed and dengue-naive adults from two studies (NCT01666652, NCT01702857). Frequencies of DPIV-induced memory B cells specific to each DENV serotype remained high up to 12 months post-vaccination, and were higher in the dengue-primed than dengue-naive adults. A subsequent DPIV booster dose induced strong anamnestic B-cell responses. Multifunctional CD4+ T cells (predominantly expressing IL-2) were induced by DPIV, with higher frequencies in dengue-primed adults. DPIV-induced CD4+ T cells also demonstrated in vitro proliferative capacity and antigen-specific production of GM-CSF, IFN-γ, and IL-13. CD8+ T-cell responses were undetectable in dengue-naive adults and low in dengue-primed individuals. B- and T-cell responses persisted up to 12 months post-vaccination in both dengue-primed and dengue-naive adults.

Randomized, Double-Blind, Reference-Controlled, Phase 2a Study Evaluating the Immunogenicity and Safety of OVX836, A Nucleoprotein-Based Influenza Vaccine.

OVX836 is a recombinant protein-based vaccine targeting the highly conserved influenza nucleoprotein (NP), which aims to confer a broad-spectrum protection against influenza. In a Phase 1 study, OVX836, administered intramuscularly, has been found safe and immunogenic. The 90µg and 180µg dose levels were selected to be further evaluated in this randomized, monocenter, reference-controlled (Influvac Tetra™: quadrivalent seasonal influenza subunit vaccine), parallel group, double-blind, Phase 2a study in 300 healthy volunteers, aged 18-65 years, during the 2019/2020 flu season. Safety, influenza-like illness episodes (ILI; based on the Flu-PRO® questionnaire) and immunogenicity were assessed up to 180 days post-vaccination. OVX836 was safe and presented a reactogenicity profile similar to Influvac Tetra. It induced a significant increase in terms of NP-specific interferon-gamma (IFNγ) spot forming cells (SFCs), NP-specific CD4+ T-cells (essentially polyfunctional cells) and anti-NP IgG responses. OVX836 was superior to Influvac Tetra for all immunological parameters related to NP, and the 180µg dose was significantly superior to the 90µg dose for SFCs and CD4+ T-cells expressing IFNγ. Both the CD4+ T-cell and the anti-NP IgG responses persisted up to Day 180. An efficacy signal was observed with OVX836 at 180µg through reduction of ILI episodes occurring during the flu season as of 14 days post-vaccination. In conclusion, these results encourage further clinical evaluation of OVX836 in order to confirm the signal of efficacy on ILIs and/or laboratory-confirmed influenza cases. NCT04192500 (https://clinicaltrials.gov/ct2/show/study/NCT04192500).

H5N1 influenza vaccine formulated with AS03 A induces strong cross-reactive and polyfunctional CD4 T-cell responses.

OBJECTIVE: Adjuvantation of an H5N1 split-virion influenza vaccine with AS03(A) substantially reduces the antigen dose required to produce a putatively protective humoral response and promotes cross-clade neutralizing responses. We determined the effect of adjuvantation on antibody persistence and B- and T-cell-mediated immune responses. METHODS: Two vaccinations with a split-virion A/Vietnam/1194/2004 (H5N1, clade 1) vaccine containing 3.75-30 µg hemagglutinin and formulated with or without adjuvant were administered to groups of 50 volunteers aged 18-60 years. RESULTS: Adjuvantation of the vaccine led to better persistence of neutralizing and hemagglutination-inhibiting antibodies and higher frequencies of antigen-specific memory B cells. Cross-reactive and polyfunctional H5N1-specific CD4 T cells were detected at baseline and were amplified by vaccination. Expansion of CD4 T cells was enhanced by adjuvantation. CONCLUSION: Formulation of the H5N1 vaccine with AS03(A) enhances antibody persistence and induces stronger T- and B-cell responses. The cross-clade T-cell immunity indicates that the adjuvanted vaccine primes individuals to respond to either infection and/or subsequent vaccination with strains drifted from the primary vaccine strain.

Comparison of the immunogenicity of the human papillomavirus (HPV)-16/18 vaccine and the HPV-6/11/16/18 vaccine for oncogenic non-vaccine types HPV-31 and HPV-45 in healthy women aged 18-45 years.

Protection against oncogenic non-vaccine types (cross-protection) offered by human papillomavirus (HPV) vaccines may provide a significant medical benefit. Available clinical efficacy data suggest the two licensed vaccines (HPV-16/18 vaccine, GlaxoSmithKline Biologicals (GSK), and HPV-6/11/16/18 vaccine, Merck & Co., Inc.) differ in terms of protection against oncogenic non-vaccine HPV types -31/45. The immune responses induced by the two vaccines against these two non-vaccine HPV types (cross-reactivity) was compared in an observer-blind study up to Month 24 (18 mo post-vaccination), in women HPV DNA-negative and seronegative prior to vaccination for the HPV type analyzed (HPV-010 [NCT00423046]). Geometric mean antibody titers (GMTs) measured by pseudovirion-based neutralization assay (PBNA) and enzyme-linked immunosorbent assay (ELISA) were similar between vaccines for HPV-31/45. Seropositivity rates for HPV-31 were also similar between vaccines; however, there was a trend for higher seropositivity with the HPV-16/18 vaccine (13.0-16.7%) versus the HPV-6/11/16/18 vaccine (0.0-5.0%) for HPV-45 with PBNA, but not ELISA. HPV-31/45 cross-reactive memory B-cell responses were comparable between vaccines. Circulating antigen-specific CD4+ T-cell frequencies were higher for the HPV-16/18 vaccine than the HPV-6/11/16/18 vaccine (HPV-31 [geometric mean ratio [GMR] =2.0; p=0.0002] and HPV-45 [GMR=2.6; p=0.0092]), as were the proportion of T-cell responders (HPV-31, p=0.0009; HPV-45, p=0.0793). In conclusion, immune response to oncogenic non-vaccine HPV types -31/45 was generally similar for both vaccines with the exception of T-cell response which was higher with the HPV-16/18 vaccine. Considering the differences in cross-protective efficacy between the two vaccines, the results might provide insights into the underlying mechanism(s) of protection.

Whole blood can be used as an alternative to isolated peripheral blood mononuclear cells to measure in vitro specific T-cell responses in human samples.

Vaccinology is confronted with diseases for which the control of T-cell responses by the vaccine is essential. Among the assays that have been designed to assess T-cell responses, intracellular cytokine staining (ICS) combined with flow cytometry is well-suited in the frame of clinical trials. This assay can be used starting from isolated peripheral blood mononuclear cells (PBMC) or from whole blood (WB), but firm equivalence between the two sample preparation methods has yet to be established. Therefore, we compared both methods by analyzing the frequency of antigen-specific CD4+ T cells expressing at least two of four immune markers in human samples taken from two independent clinical trials (NCT00397943 and NCT00805389) with a qualified ICS assay. In the first study, M72-specific CD4+ T-cell responses were analyzed using WB-ICS and PBMC-ICS in 293 samples. Of these, 128 were double positive (value ≥ lower limit of quantification [LLOQ] with both methods), 130 were double negative and only 35 sample results were discordant, leading to an overall agreement of 88.05%. When analyzing the 128 double positive samples, it was found that the geometric mean of ratios (GMR) for paired observations was 0.98, which indicates a very good alignment between the two methods. The Deming regression fitted between the methods also showed a good correlation with an estimated slope being 1.1085. In the second study, HBsAg-specific CD4+ T-cell responses were analyzed in 371 samples. Of these, 100 were double positive, 195 were double negative and 76 sample results were discordant, leading to an overall agreement of 79.51%. The GMR for paired observations was equal to 1.20, caused by a trend for overestimation in favor of the WB samples in the very high frequencies. The estimated slope of the Deming regression was 1.3057. In conclusion, we demonstrated that WB and PBMC methods of sample collection led to statistically concordant ICS results, indicating that WB-ICS is a suitable alternative to PBMC-ICS to analyze clinical trial samples.

Safety and Immunogenicity of an AS03B-Adjuvanted Inactivated Tetravalent Dengue Virus Vaccine Administered on Varying Schedules to Healthy U.S. Adults: A Phase 1/2 Randomized Study.

Dengue disease and its causative agents, the dengue viruses (DENV-1-4), cause high morbidity in tropical and subtropical regions. We evaluated three dosing regimens of the investigational tetravalent AS03B-adjuvanted dengue-purified inactivated vaccine (DPIV+AS03B). In this phase 1/2, observer-blind, placebo-controlled study (NCT02421367), 140 healthy adults were randomized 1:1:2 to receive DPIV+AS03B according to the following regimens: 0-1 month (M), 0-1-6 M, or 0-3 M. Participants received DPIV+AS03B or placebo at M0, M1, M3, and M6 according to their dosing schedule. Primary objectives were 1) to evaluate the safety of DPIV+AS03B for 28 days (D) after each dose; 2) to demonstrate the added value of a booster dose (0-1-6 M versus 0-1 M) based on neutralizing antibody titers to each DENV type (DENV-1-4) at 28 D after the last dose; and, if this objective was met, 3) to demonstrate the benefit of a longer interval between the first and second doses (0-1 M versus 0-3 M). Adverse events (AEs) within 7 D after vaccination tended to be more frequent after DPIV+AS03B doses than placebo; the number of grade 3 AEs was low (≤ 4.5% after DPIV+AS03B; ≤ 2.9% after placebo), with no obvious differences across groups. Within 28 D following each dose, the frequency of unsolicited AEs after DPIV+AS03B appeared higher for three-dose (0-1-6 M) than two-dose (0-1 M and 0-3 M) regimens. No serious AEs were considered related to vaccination, and no potential immune-mediated diseases were reported during the study. All three schedules were well tolerated. Both primary immunogenicity objectives were demonstrated. The 0-3 M and 0-1-6 M regimens were more immunogenic than the 0-1 M regimen.

The candidate tuberculosis vaccine Mtb72F/AS02A: Tolerability and immunogenicity in humans.

Tuberculosis (TB) remains uncontrolled in many parts of the world and the development of an effective vaccine against TB represents a high priority unmet medical need. Healthy PPD (tuberculin purified protein derivative)-negative adult volunteers, aged 18-40 years received three doses of the candidate Mtb72F/AS02A vaccine according to a 0-1-2 months schedule in an open-label Phase I study (NCT00730795). Solicited, unsolicited and serious adverse events (AEs), hematological and biochemical laboratory parameters were assessed. Mtb72F-specific humoral responses were assessed by ELISA and cell-mediated immune (CMI) responses by intracellular cytokine staining (ICS) and short-term ELISPOT assays. CMI responses to the component peptides (Mtb39a and the Mtb32a C- and N-terminal antigen domains, Mtb32C and Mtb32N) were also assessed by ICS. The Mtb72F/AS02A vaccine appeared to be mainly locally reactogenic but this was considered acceptable, since these AEs were usually transient and resolved within 1-2 days. Most AEs reported were mild in intensity, no serious AEs occurred, no medically significant biochemical or hematological abnormalities related to vaccination were measured and all AEs resolved without sequelae. The vaccine induced statistically significant changes in humoral and CMI response measures. The Mtb72F antigen induced good production of IL-2 and IFNgamma in the ELISPOT assay and CD4(+) T cells expressing at least two activation markers (mainly CD40-L and IL-2) were observed with ICS. A similar CMI profile was observed with Mtb39a and Mtb32N. The induced CMI responses persisted for at least 6 months post-vaccination. All subjects were seropositive for anti-Mtb72F antibodies one month post-dose 2 and 6 months post-dose 3. This first trial in humans found Mtb72F/AS02A to have an acceptable tolerability, to be immunogenic in healthy adults and warrants further development of the vaccine.

Cell-mediated immune responses to different formulations of a live-attenuated tetravalent dengue vaccine candidate in subjects living in dengue endemic and non-endemic regions.

Three phase II randomized trials evaluated the safety/immunogenicity of two formulations of live-attenuated tetravalent dengue virus (TDEN) vaccine in dengue-endemic (Puerto Rico, Thailand) and non-endemic (US) regions (NCT00350337/NCT00370682/NCT00468858). We describe cell-mediated immune (CMI) responses; safety and humoral responses were reported previously. Participants received two doses of vaccine or control (placebo or the precursor live-attenuated TDEN vaccine) 6 months apart. Selected US participants received a booster 5-12 months post-dose 2. Evaluated subsets of the per-protocol cohorts included 75 primarily dengue virus (DENV)-unprimed US adults, 69 primarily flavivirus-primed Thai adults, and 100 DENV-primed or DENV-unprimed Puerto Rican adults/adolescents/children. T-cell responses were quantified using intracellular cytokine staining (ICS; DENV-infected cell-lysate or DENV-1/DENV-2 peptide-pool stimulation) or IFN-γ ELISPOT (DENV-2 peptide-pool stimulation). Memory B-cell responses were quantified using B-cell ELISPOT. Across populations and age strata, DENV serotype-specific CD4+ T-cell responses were slightly to moderately increased (medians ≤0.18% [ICS]), DENV-2-biased, and variable for both formulations. Responses in unprimed subjects were primarily detected post-dose 1. Response magnitudes in primed subjects were similar between doses. Multifunctional CD8+ T-cell responses were detected after peptide-pool stimulation. T-cell responses were mostly directed to DENV nonstructural proteins 3 and 5. Memory B-cell responses were tetravalent, of low-to-moderate magnitudes (medians ≤0.25%), and mainly observed post-dose 2 in unprimed subjects and post-dose 1 in primed subjects. A third dose did not boost CMI responses. In conclusion, both formulations of the live-attenuated TDEN vaccine candidate were poorly to moderately immunogenic with respect to B-cell and T-cell responses, irrespective of the priming status of the participants. Abbreviation ATP: according-to-protocol; ICS: Intracellular Cytokine Staining; NS3: Nonstructural protein 3; ELISPOT: Enzyme-Linked ImmunoSpot; JEV: Japanese encephalitis virus; PBMC: peripheral blood mononuclear cells.

Non-typeable Haemophilus influenzae protein vaccine in adults with COPD: A phase 2 clinical trial.

Loss of airway microbial diversity is associated with non-typeable Haemophilus influenzae (NTHi) infection and increased risk of exacerbation in chronic obstructive pulmonary disease (COPD). We assessed the safety and immunogenicity of an investigational vaccine containing NTHi antigens, recombinant protein D (PD) and combined protein E and Pilin A (PE-PilA), and AS01 adjuvant in adults with moderate/severe COPD and prior exacerbations. In this phase 2, observer-blind, controlled trial (NCT02075541), 145 COPD patients aged 40-80 years randomly (1:1) received two doses of NTHi vaccine or placebo 60 days apart, on top of standard care. Reactogenicity in the 7-day post-vaccination period was higher following NTHi vaccine than placebo. Most solicited adverse events (AEs) were mild/moderate. At least one unsolicited AE was reported during the 30-day post-vaccination period by 54.8% of NTHi vaccine and 51.4% of placebo recipients. One serious AE (placebo group) was assessed by the investigator as vaccine-related. Anti-PD, anti-PE and anti-PilA geometric mean antibody concentrations increased up to 30 days after each NTHi vaccine dose, waned thereafter, but remained higher than baseline (non-overlapping confidence intervals) up to 13 months post-dose 2. The frequency of specific CD4+ T cells increased following two doses of NTHi vaccine and remained higher than baseline. Exploratory analysis showed a statistically non-significant lower yearly rate of moderate/severe exacerbations in the NTHi vaccine group than following placebo (1.49 versus 1.73) in the one-year period post-dose 2, with estimated vaccine efficacy of 13.3% (95% confidence interval -24.2 to 39.5; p = 0.44). The NTHi vaccine had an acceptable safety and reactogenicity profile and good immunogenicity in adults with COPD.

Characterization of T-cell immune responses in clinical trials of the candidate RTS,S malaria vaccine.

The candidate malaria vaccine RTS,S has demonstrated 45.7% efficacy over 18 months against all clinical disease in a phase-III field study of African children. RTS,S targets the circumsporozoite protein (CSP), which is expressed on the Plasmodium sporozoite during the pre-erythrocyte stage of its life-cycle; the stage between mosquito bite and liver infection. Early in the development of RTS,S, it was recognized that CSP-specific cell-mediated immunity (CMI) was required to complement CSP-specific antibody-mediated immunity. In reviewing RTS,S clinical studies, associations between protection and various types of CMI (CSP-specific CD4+ T cells and INF-γ ELISPOTs) have been identified, but not consistently. It is plausible that certain CD4+ T cells support antibody responses or co-operate with other immune-cell types to potentially elicit protection. However, the identities of vaccine correlates of protection, implicating either CSP-specific antibodies or T cells remain elusive, suggesting that RTS,S clinical trials may benefit from additional immunogenicity analyses that can be informed by the results of controlled human malaria infection studies.

A Randomized, Controlled Safety, and Immunogenicity Trial of the M72/AS01 Candidate Tuberculosis Vaccine in HIV-Positive Indian Adults.

Human immunodeficiency virus (HIV)-associated tuberculosis is a major public health threat. We evaluated the safety and immunogenicity of the candidate tuberculosis vaccine M72/AS01 in HIV-positive and HIV-negative Indian adults.Randomized, controlled observer-blind trial (NCT01262976).We assigned 240 adults (1:1:1) to antiretroviral therapy (ART)-stable, ART-naive, or HIV-negative cohorts. Cohorts were randomized 1:1 to receive M72/AS01 or placebo following a 0, 1-month schedule and followed for 12 months (time-point M13). HIV-specific and laboratory safety parameters, adverse events (AEs), and M72-specific T-cell-mediated and humoral responses were evaluated.Subjects were predominantly QuantiFERON-negative (60%) and Bacille Calmette-Guérin-vaccinated (73%). Seventy ART-stable, 73 ART-naive, and 60 HIV-negative subjects completed year 1. No vaccine-related serious AEs or ART-regimen adjustments, or clinically relevant effects on laboratory parameters, HIV-1 viral loads or CD4 counts were recorded. Two ART-naive vaccinees died of vaccine-unrelated diseases. M72/AS01 induced polyfunctional M72-specific CD4 T-cell responses (median [interquartile range] at 7 days postdose 2: ART-stable, 0.9% [0.7-1.5]; ART-naive, 0.5% [0.2-1.0]; and HIV-negative, 0.6% [0.4-1.1]), persisting at M13 (0.4% [0.2-0.5], 0.09% [0.04-0.2], and 0.1% [0.09-0.2], respectively). Median responses were higher in the ART-stable cohort versus ART-naive cohort from day 30 onwards (P ≤ 0.015). Among HIV-positive subjects (irrespective of ART-status), median responses were higher in QuantiFERON-positive versus QuantiFERON-negative subjects up to day 30 (P ≤ 0.040), but comparable thereafter. Cytokine-expression profiles were comparable between cohorts after dose 2. At M13, M72-specific IgG responses were higher in ART-stable and HIV-negative vaccinees versus ART-naive vaccinees (P ≤ 0.001).M72/AS01 was well-tolerated and immunogenic in this population of ART-stable and ART-naive HIV-positive adults and HIV-negative adults, supporting further clinical evaluation.

Safety and immunogenicity of the M72/AS01E candidate tuberculosis vaccine in adults with tuberculosis: A phase II randomised study.

Previous studies have shown that the M72/AS01E candidate tuberculosis vaccine is immunogenic with a clinically acceptable safety profile in healthy and Mycobacterium tuberculosis-infected adults. This phase II, observer-blind, randomised study compared the safety, reactogenicity, and immunogenicity of M72/AS01E in 3 cohorts: tuberculosis-naïve adults (n = 80), adults previously treated for tuberculosis (n = 49), and adults who have completed the intensive phase of tuberculosis treatment (n = 13). In each cohort, 18-59-year-old adults were randomised (1:1) to receive two doses of M72/AS01E (n = 71) or placebo (n = 71) and followed-up until six months post-dose 2. Safety and reactogenicity were assessed as primary objective. Recruitment in the study ended prematurely because of a high incidence of large injection site redness/swelling reactions in M72/AS01E-vaccinated adults undergoing tuberculosis treatment. No additional clinically relevant adverse events were observed, except one possibly vaccine-related serious adverse event (hypersensitivity in a tuberculosis-treated-M72/AS01E participant). Robust and persistent M72-specific humoral and polyfunctional CD4(+) T-cell-mediated immune responses were observed post-M72/AS01E vaccination in each cohort. In conclusion, the M72/AS01E vaccine was immunogenic in adults previously or currently treated for tuberculosis, but further analyses are needed to explain the high local reactogenicity in adults undergoing tuberculosis treatment. ClinicalTrials.gov: NCT01424501.