Recombinant nanoparticle RSV F vaccine for respiratory syncytial virus: Preclinical efficacy and clinical safety

1. Recombinant nanoparticle RSV F vaccine for respiratory syncytial virus:  Preclinical efficacy and clinical safety and immunogenicity Y Y Y Y Y Y Y RSV F RSV F RSV F RSV F Y RSV F RSV F RSV F RSV F RSV F RSV F RSV F RSV F RSV F RSV F RSV F RSV F SA SA SA SA SA SA SA SA SA SA SA SA SA SA SA SA Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y PRECLINICAL EFFICACY IMMUNOGENICITY Gregory Glenn1, Rama Raghunandan1, Hanxin Lu1, Bin Zhou1, Kwan Ngai1, Gulshan Dhariwal1, Eloi Kpamegan1, Michael J. Massare1, Steven Pincus1, Lou Fries1, Piedra Pedro2, Letisha Aideyan2, Gale Smith1 1Novavax, 9920 Belward Campus Drive, Rockville MD 20850; 2Baylor College Of medicine, Department of Molecular Virology and Microbiology, and Pediatrics Houston Texas The vaccine was well tolerated with the primary finding of mild local AEs and no dose effect The vaccine was immunogenic inducing high titer antibodies that recognize the RSV F protein despite the presence of preexisting anti-F immunity High levels of seroconversion were observed including 100% in the high dose alum group A significant dose-response and alum effect was observed and a second dose appeared to further enhance the immune responses Antibodies that recognize the palivizumab epitope were increased over 20 fold and vaccine induced antibodies compete strongly with palivizumab PRNTs were significantly enhanced compared to placebo and reverse cumulative plots indicated that individuals with low titers were eliminated Post-immunization PRNTs in vaccine groups exceeded levels that have been estimated to be protective in the elderly, children and infants The RSV F recombinant nanoparticle vaccine appears to safely induce high levels of functional immunity and together the data indicate that this promising vaccine candidate should be further developed CONCLUSIONS IMMUNOGENICITY (contd.) CLINICAL SAFETY INTRODUCTION RSV is the most important viral cause of lower respiratory tract infection in infants and children worldwide. The global disease burden is estimated at 64 million cases and 160,000 deaths every year. In the United States RSV is the most common cause of bronchiolitis and pneumonia and hospitalization with 90,000 to 140,000 children < 1 year of age are hospitalized due to RSV infection. Up to 60 per 1,000 children <3 months are hospitalized annually. Similarly, an estimated 8.5 million adults, primarily the elderly, are infected with RSV resulting in 900,000 hospitalizations annually due to RSV in the United States and major European countries. In the United States alone there are 177,500 hospitalizations among high-risk adults resulting in annual medical costs exceeding $1 billion. There is currently no approved vaccine for the prevention of RSV. The RSV Fusion (F) surface glycoprotein protein is conserved across all strains and represents an important vaccine target. Synagis® (palivizumab) and Respigam® prophylactic antibodies target neutralizing epitopes on the F protein and have had a major impact on the RSV burden of disease in premature infants. The baculovirus/Sf9 insect cell system is conceptually ideal for the production of a surface glycoprotein vaccine antigen as the induction of a viral infection leads expression of the antigen via pathways designed to properly fold and produce antigen in its native configuration. The RSV F nanoparticle vaccine is composed of full length F protein that is cleaved into disulfide linked F1 and F2 trimers which form highly stable 20-40 nm micelles due to the interaction of the hydrophobic regions via protein/protein interactions. In preclinical studies, the RSV F nanoparticle vaccine induces neutralizing antibodies and complete protection in challenge animals. In this Phase 1 trial, the BV/Sf9 RSV F nanoparticle vaccine was evaluated in a dose escalation safety and immunogenicity trial. The immunogenicity evaluations including neutralization assays, ELISA against the native protein, ELISA and competitive ELISA against palivizumab epitopes, allow comparison of vaccine responses to naturally occurring protective antibodies and palivizumab and thus provide an estimation of the potential for efficacy as a prophylactic vaccine. Competition between RSV F Induced Antibodies in Mice with Synagis Binding of Synagis® to Palivizumab Epitope Peptide and Recombinant RSV F • Clinical Study Design • Phase 1 randomized, observer blinded placebo controlled trial to evaluate the Safety and Immunogenicity of a Respiratory Syncytial Virus F recombinant nanoparticle vaccine in healthy adults in a dose-escalating fashion. • 150 healthy adults administered two immunizations at day 0 and day 30. • Primary Objective: Safety • Solicited AEs (local and systemic) diary card 1-7 days post immunizations • Unsolicited AEs • Follow through day 210 (180 days after the last injection) • Secondary Objective: Immunogenicity • Compare the immunogenicity of the 6 different vaccine formulations • Evaluate the alum adjuvant effect • Evaluations: Primary • Total anti-RSV F antibody • Plaque Reduction Neutralizing Antibodies or PRNT • Exploratory • RSV F palivizumab peptide ELISA and Synagis competitive ELISA 254-278 NSELLSLINDMPITNDQKKLMSNNV palivizumab epitope • A. Binding of SynagismAb to Palivizumab Epitope Peptide.ELISA plates were coated with streptavidin at 5ug/ml. Palivizumab peptide at 1ug/ml was bound on to Streptavidin. Synagis at 10ug/ml was serially diluted four fold and incubated to the peptide on the plate. Synagis binding was detected using anti human HRP reaction. • Binding of Synagis to Recombinant RSV F micells. ELISA plates were coated with 2ug/ml RSV F micelle antigen. Synagis at 10ug/ml concentration serially diluted four fold and reacted to RSV F on the plate. Anti human HRP reaction was used to determine the Synagis binding to RSV F micelles. An unweighted four parameter logistic regression curve is presented. Competitive ELISA with anti-RSV F Vaccinated Mouse Serum and Synagis. ELISA plates were coated with RSV F micelle at 2ug/ml. Pre immune and a pool of day28 serum from mice immunized on day 0 with 30ug RSV F with alum were mixed with 50ng/ml biotin-palivizumab then serially diluted and incubated with purified RSV F coated ELISA plate. Streptavidin was used to determine palivizumab bound to the plate. An unweightedfour parameter logistic regression curve is presented. RSV F IgG against Synagis Peptide Plaque Reduction Neutralizing Titers PRNTs: 30mg with Alum Group Demographic and Baseline Characteristics Safety Population Electron Microscopy Purified RSV F Nanoparticle Vaccine Pre-fusion RSV F “Lollipop” Day 30 and 60 antibodies significantly higher than placebo p,0,0001 Reverse Cumulative Distribution for Day 0, 30 and 60 PRNTs in the Placebo and 30 mg with Alum groups. Minimum titers at day 0 are 5 log2 and minimum titer post-immunization with RSV F recombinant nanoparticle at day 60 is 8.5 log2. Primary Safety Findings RSV Challenge in RSV F Nanoparticle Vaccine Immunized Cotton Rats • Local Pain • % in Placebo: 6.7% • Range in vaccine groups: 15.0% to 55.0% • % Severe: 5% (1 subject, 30 ug+Alum) • Dose response: None • Tenderness • % in Placebo: 10% • Range in vaccine groups: 20% to 55% • % Severe: 5% (1 subject, 60 ug+Alum) • Dose response: None • Headache • % in Placebo: 16.7% • Range in vaccine groups: 10% to 35% • % Severe: None • Dose response: None PRNT Response to RSV F Nanoparticle Vaccine In Cotton Rats Subject Disposition • No deaths occurred in the study • No withdrawals due to an adverse event Safety Summary • Overall vaccine was well tolerated • Majority of AEs were local pain and tenderness and the majority were mild • Local AEs were higher in vaccine group compared to placebo • No dose effect or AE trend based on dose • No systemic signal in the vaccine groups • No vaccine related SAEs RSV F/SynagisPeptide ELISA Anti-RSV F IgG ELISA RSV Plaque Reduction Neutralizing Titers F Peptide F .Pulmonary RSV viral titers in cotton rats immunized with RSV F particle vaccine ±alum and challenged with live RSV A strain virus. Cotton Rats were immunized with RSV F particle vaccine on day 0 and day21, challenged with RSV A strain virus on day49. Lung tissues were harvested on day 54 (n=8/group), homogenized and evaluated for the presence of RSV virus using a Hep-2 monolayer plaque assay to detect infectious virus. RSV titers are expressed as pfu/per gram of tissue are shown ± SEM. Anti RSV F IgG Assays Used in the Immunogenicity Evaluations Neutralizing antibody responses against RSV A in cotton rats immunized with RSV F vaccine ± alum. Cotton rats were immunized on day 0 and 21 and bled on day 21 and 49. Serum from day 49 was tested against RSV-A in neutralizing assays. Results expressed as geometric mean of end point titer that neutralize 100% F Strept-avidin +Biotinylated peptides RSV F Micelle RSV Virus Virus + Serum (1:10) Human Sera Cotton Rat Anti RSV F IgG Peptide+ Phase I Human Sera RSV F +Phase I Human Sera Virus +Hep-2 Serum+Virus +Hep-2 Plaque Y Y Human Sera+ Anti Human HRP Human Sera + Anti Human HRP Plaque Positive Virus Neutralized TMB TMB Colored Substrate Colored Substrate Y Y Anti Human HRP+ TMB substrate Anti Human HRP+ TMB substrate ELISA using pooled sera, reporting the 50% titer on a 4 parameter fit dilution curve as ELISA Units Geometric Mean Titers (GMT) and 95% Confidence IntervalsTotal Anti RSV F IgGELISA Per-Protocol Population Anti RSV F IgG Geometric Mean Fold Rise, Alum Groups Geometric means and 95% confidence intervals are calculated as the antilog of the mean and 95% confidence limits of log (base 10) transformed total anti-F IgG titer values. [1] P-value is from t-test on log (base 10) transformed titer values comparing the specified treatment group to the RSV-F 30 µg unadjuvanted group. [2] P-value is from t-test on log (base 10) transformed titer values comparing the specified treatment group to the RSV-F 60 µg unadjuvanted group. [3] P-value is from t-test on log (base 10) transformed titer values comparing the specified treatment group to the Placebo group. Geometric Mean Fold Rise (GMFR) Total Anti RSV F IgGELISA Per Protocol Population