“Vaccinology and Immunotherapy” Dr. Saddam M. (DVM, Immunologist/Vaccinologist) University of Gondar June, 2023 Edward Jenner Used principle of cross protection Vaccine can be therapeutic for example BCG for TB administered after being diseased, i.e it is given for sick animals or human. Regarding vaccination advocacy people can be either of the three categories. Pro, Hesitant, or anti. French's are fist level vaccine resistant people in the world. They usually raise vaccination scandal thinking that government is influenced by billion dollar companies. Addressing hesitant would add them to the pro group of Pro. Hesitant should be addressed with trusted scientific community. Infant mortality has remarkably decreased by vaccination. Antivaxors are not supposed to be convinced at all. Famouse anit vaxor: Andrew Jeremy Wakefield is a British anti-vaccine activist. In 1998, he and 12 of his colleagues published the paper that the MMR vaccine is the cause of autism. Another example is : middle east. Resist the pork gelatin product product in the vaccine. In February 2021, the Peruvian 'vaccinegate' scandal broke when the media reported that nearly 500 experimental doses of an ongoing COVID-19 trial were given to key individuals not enrolled in the trial. Scandal: an action or event regarded as morally or legally wrong and causing general public outrage. Covid: The first mRNA vaccine licensed Nucleic acid vaccine have the disadvantage of: genotoxicty, oncogenesis, integrating to Host DNA. Vaccine safety study continues life long. The aim of vaccination is Mimicking the invading pathogen Malaria was licensed with 37% efficacy. Purified Antigen can be given as a vaccine. E.g., Purified Human Prostate Specific Antigen. What are Vaccines? = vaccines are biological preparations that work by stimulating the immune system and that are administered to healthy (or sick) animals/humans for the purpose of prevention (or treatment) of a disease respectively Pro? Anti The discovery of vaccine adjuvants dates back to 1925, where Gaston Ramon showed that co-administration of his newly invented diphtheria toxoid together with other compounds such as tapioca, lecithin, agar, starch oil, saponin or breadcrumbs increased antitoxin responses to diphtheria. This was followed up by Glenny and coworkers, who in 1926 demonstrated that diphtheria toxoid precipitated with aluminum salts resulted in significant increase of the immune response to the toxoid. The most widely used adjuvant is aluminium salt which was first used by the immunologist, Alexander T. Glenny, in 1926 at the Wellcome Physiological Research Laboratory in London. In an attempt to purify and concentrate diphtheria toxoids (inactive toxin), Glenny and colleagues used potassium aluminium sulfate in the production of the vaccine. Surprisingly, they found that vaccines developed using aluminium salt precipitation led to better antibody responses in guinea pigs than the soluble toxoids — the first demonstration of aluminium salt adjuvanticity. Adjuvant: carrier proteins are not adjuvant, adjuvant have depot effect, One of the proposed hypotheses of the mechanism behind the immunostimulatory effect obtained with the cationic liposomal vaccine adjuvant is the ‘depot effect’ in which the liposomal carrier helps to retain the antigen at the injection site thereby increasing the time of vaccine exposure to the immune cells. Adjuvants trigger inflammation due to PRR engagement and activation of inflamasome. Giving an antigen only leads to tolerogenic antigen and autimmunity will occur. Live attenuated vaccines don’t need adjuvants. It has inherent adjuvanticity. For immunologically non responsive vaccines(for old and young age) adjuvant will make them good. Vaccines are the only scientific technology that we apply, or attempt to apply, to every singe human being on the Earth. There is nothing like that in medicine” Gregory A. Poland (M.D., MACP, FIDSA) Mayo Clinic – US “With the exception of safe water, no other medicine or treatment, not even antibiotics, has had such a major effect on mortality reduction...” Impact of vaccination 1. 2. 3. 4. Decreased mortality Improve productivity Decreased morbidity Global financial burden Immunology of spike protein is identifying the dominant antigen from the desired antigen. E.g., There are four major structural proteins in the SARS-CoV, including the nucleocapsid, spike, membrane, and small envelope proteins. The wider safety margin of a vaccine is because we are giving it to healthy individuals not for sick as drugs. Vaccines should be affordable Easy safe and low cost of discovery. Vaccines should have customized approach Multiple discount projects are required for vaccine. After prioritizing the disease vaccine should have product characterization. Early de risking before production remove safety issues. Some times disease inhancement make us change the vaccine characterization after production. Eg. The case of dungue virus Trying to make vaccine without understanding pathogenesis is fisky e.g., rota virus vaccine was the cause of intussusception Standard of care won’t be stopped when we are doing clinical trial. e.g., if we are giving a vaccine for HIV, we can’t sotp ART. Introduction — The vaccine specificities Prophylactic vaccines... • Are given to healthy individuals • Are usually administered to very large number of people • Are needed across the globe and must be affordable to everyone • May need to protect for a long period of time • Need to be convenient to administer • Take significant time and investment to be developed The vaccine specificities require a customized approach, including at discovery stage Introduction — Attrition rates in vaccine development High attrition in the early stage of vaccine discovery • Multiple Discovery Projects are required to ensure pipeline sustainability • Decisiveness is key: — Asset level — Portfolio level • Adopt ways of working in Discovery that ensure flexibility and sustainability Introduction — Table of Content Given the vaccine peculiarities, it is important to optimize the discovery phase: • Identify & prioritize the right disease target • Determine early on the mandatory vs desired product characteristics of the future vaccine => target product profile (TPP) • Select the right vaccine approach/technological platform • Validate the vaccine concept early on =>“ early DE-RISKING” The TPP is essentially an organized “wish-list” of characteristics, features, and attributes that one would liketo see in a newly developed medical product once it reaches the market. IDENTIFICATION AND PRIORITIZATION OF THE DISEASE TARGET Criteria for selecting & prioritizing new disease targets 1. Medical need, disease burden & economical burden: a. Disease incidence and severity b. Disease impact Individual vs society Short-term vs long-term Direct vs indirect 2. Pathogenesis & disease understanding a. Causality between the pathogen & the disease b. Factors driving disease severity 3. Protective immune response 4. Technical feasibility 5. Clinical feasibility Ill. Protective immune response: • Protective role of antibodies: • Animal studies • Protective monoclonal antibodies • Protective role of maternally derived antibodies • Protective role of T cells: • Animal studies • Disease in patients with allogenic bone marrow transplant • Immune response associated with disease resolution • Awareness of prior unsuccessful vaccine trials: IV. Technical feasibility: • Is it possible to induce a broad protection against all strains & serotypes of the pathogen with only a few antigens/vaccine components? • Is there a vaccine approach that can deliver the desired immune response? => Antibodies & CD8 T cell • For the selected approach, do we think we will be able to scale-up the production process to produce millions of dose per year? • Will the cost of goods be compatible with the estimated vaccine price? V. Clinical feasibility: a. Is it possible to demonstrate a proof of concept early in the development? Is there a population with increased disease incidence? b. Can we show efficacy using a reasonable number of volunteers using an endpoint that would convince both regulatory agencies & recommending bodies? c. Is it possible to identify & enroll the necessary number of volunteers in clinical trials? how many countries & centers? d. Is there an immunological endpoint that can help us: 1. Measuring vaccine take? 2. Selecting the final dose/formulation? 3. Predicting vaccine efficacy? What are endpoints when used in a clinical trial? Biomarkers, are defined characteristics that are measured as indicators of health, disease, or a response to an exposure or intervention, including therapeutic interventions . Biomarkers can help diagnose a disease, or predict future disease severity or outcomes, like measurements of blood pressure as an indicator of cardiovascular risks or measurements of blood sugar in diabetes. Biomarkers also are used to identify the best treatment for a patient, to monitor the safety of a therapy, or to find out if a treatment is having the desired effect on the body. A clinical trial’s “endpoints” are measurements of what happens to people in the trial. When a trial is intended to evaluate the efficacy and safety of a new medical product or a new use of an approved product, its endpoints usually measure benefit. Investigators typically use either clinical or surrogate endpoints. Surrogate endpoints are used when the clinical outcomes might take a very long time to study, or in cases where the clinical benefit of improving the surrogate endpoint, such as controlling blood pressure, is well understood. Clinical trials are needed to show that surrogate endpoints can be relied upon to predict, or correlate with, clinical benefit. Surrogate endpoints that have undergone this testing are called validated surrogate endpoints and these are accepted by the regulatory body as evidence of benefit. Found diseased, dead, survival, measuring critical viral load between vaccinated and unvaccinated subjects are the good end points. Toxins need antibody mediated vaccine. Subunit vaccine induce antibody response. Prior unsuccessful vaccine is important to the coming generation of vaccines optimization factors Identifying T cell epitop. Bactericidal antibody is is the immunologic surrogate of protection against meningococcal disease! Vaccine feasibility check Volunteer Reasonable endpoint : to show efficalcy and get license In meningococcus licensing For protection and guarantee •Immunologic endpoint is done in the laboratory •Clinical endpoint : severity Bactericidal antibody: bactericidal assay Virus : cell culture and lesion induction and or lysis Sweet spot : inclusive Selecting the right vaccine approach The RSV Paediatric example GSK’s approach for RSV paediatric vaccine candidate = Recombinant adenovector coding for RSV F, N and M2-1 antigens => Early control of infection & virus load by: Neutralizing antibodies directed against the F protein CD8 T cells directed against F, N & M2.1 to clear infected cells => Good quality immune response induced by the adenovector: Intra-cellular expression of the RSV antigens, as with live RSV virus Induction of a Th1 or balanced Th1/Th2 immune response => Scalability of the platforms demonstrated Early Project De-Risking Why? • Avoid exposing volunteers to an investigational vaccine that is unlikely to offer significant benefit • Limit at-risk investment • Opportunity cost How? • Identify what are the key risks of the project • Design & prioritize experiments assessing those risks • Stop unsuccessful projects. Accelerate/invest in those for which the major nsk have been discharged The RSV Paediatric example Key risk/question: • Could the RSV vaccine promote disease enhancement? Will the vaccine offer protection against the disease? 1. Existence of multiple serotypes (e.g. rhinovirus, S. suis, FMD, BTV, Pasteurella): induction of cross-protection. 2. Search for stronger adjuvant systems 3. New immune correlates of protection(systems biology approaches) 4. Antigenic variation(e.g. influenza, Borrelia, HIV) 5. Failure to induce sufficient CD4 T helper/CTL activity (Tuberculosis) 6. Complex life cycle of pathogen e.g. Malaria parasite 7. Virus escape mechanisms (herpesviruses) 8. Antigenic competition- purely empirical; some vaccines work fine together (e.g. DPT), others don’t. 9. Passive (maternal) antibody interference during first weeks/months of newborn Therapeutic vaccines for cancer and HIV Infectiou s challeng e experime nts In vivo product ion of organis ms Small market volum e Veterinar y Vaccinolo gy Less rigorou s regulati on Limite d Resear ch fundin g “Vaccinology and Immunotherapy” Dr. Saddam M. (DVM, Vaccinologist) University of Gondar College of Veterinary Medicine and Animal Sciences June, 2023 Preclinical Antigenicity Immunogenicity • Antigen & Adjuvant Justification Requirements for regulatory Authorities Prior to First Time in Human Clinical Trials Efficacy Safety (toxicology) *preclinical efficacy can be tested when relevant animal model exists for that particular disease! Nature of the pathogen in question Life cycle, structure, replication… Epidemiology of the disease Affected age group, geographical distribution (local, regional, pandemic) Intended users Pregnant, pediatrics, geriatrics… In case of animal vaccines–species of animals, purpose of the animal kept Technical feasibility Clinical feasibility Economical feasibility First lecture Impact of Pathogen Life cycle on Vaccine Design Extracellular vs Intracellular Extracellular & intracellular pathogens: targeting antigens on surface of pathogen Prevent infection & dissemination by vaccine design that induces antibodies and CD4 T cells. • Inactivated pathogen , recombinant proteins etc... Intracellular pathogen: • Eliminate infected cells & prevent dissemination by vaccine design that induces CD8 and CD4 T cells. Attenuated pathogens, live vaccine vectors etc..... Conventionally attenuated vaccines Genetically/rationally attenuated vaccines Whole inactivated vaccines (Recombinant) subunit vaccines DNA vaccine RNA vaccines Antigen discovery: • Sequence based approach • HT proteomics • Peptide libraries Virus Like Particles (VLP) based vaccines Vectored vaccines: DC-based, viral-vectored computational Antigen Selection and Discovery Antigen Discovery Reverse vaccinology • Entire pathogen genome screened using bioinformatics to identify appropriate vaccine antigen targets. • Antigen candidates identified in the genome with the specific attributes required can then be screened in animal models. Example: Identification of the vaccine candidate for group B meningococcus vaccine (Pizza et al. science 287 2000) Conventional laboratory-based, experimental microbiological approaches to antigen identification typically starts with the cultivation of the target pathogenic microorganism under laboratory conditions, Attenuate or inactivate the agent OR dissecting them into their component proteins, assaying these in some cascade of in vitro and in vivo assays, leading ultimately to the identification of proteins which display requisite protective immunity However, it is not always possible to cultivate a particular pathogen outside of the host organism e.g.???? Many proteins are only expressed transiently during the course of infection. Nor are all proteins easily expressed in Thus, many potential candidate vaccines may be missed sufficient quantities in vitro • Figure 7.1. Scheme representing the classical approach for antigens production • (a) and more advanced approaches (b—d) (a) The whole pathogen is isolated and inactivated, or it is produced in a attenuated version. • (b) Recombinant subunit antigens: The molecule responsible for immunogenic response is identified, its gene is cloned, and the protein is overexpressed and purified. • (c) Reverse Vaccinology: Starting from a pathogen's sequenced genome, many potential antigen candidates are identified, cloned, expressed, and purified. • (d) 'tructurg (Vaccinology: This approach is aimed at improving known antigens [obtained through (b)or following rational design based on the three-dimensional structure of the protein. REVERSE VACCINOLOGY The ultimate goal of RV and other discovery techs: to deliver a shortlist of antigens which can be validated through subsequent laboratory examinations! • In 2000, a new resource for meningococcal vaccine development became available with completion of the genome of the virulent MenB strain MC58, giving in silico access to 2158 predicted ORFs to screen for novel vaccine antigens. • Assuming that surface-exposed antigens are the most suitable vaccine candidates, due to their potential to be recognized by the immune system, the draft MC58 genome was screened using bioinformatics tools, leading to the identification of 570 ORFs predicted to encode either surface-exposed or secreted proteins. • Antigen selection then continued based on a number of criteria: • the ability of candidates to be cloned and expressed in E. coli as recombinant proteins (350 candidates); • the confirmation of surface exposure by ELISA and FACS analysis (91 candidates); • • the ability of induced antibodies to elicit protective immunity, as measured by serum bactericidal assay and/or passive protection in infant rats (28 candidates); and screening to determine the conservation of antigens within a panel of diverse meningococcal strains, primarily containing disease-associated MenB strains. Selection of Antigen from Pathogen Based on existing preclinical or clinical data • Different parts of the pathogen can be the target of antibodies or T cells • An immune response to 1 or multiple antigens may be needed for protection • The protection against different types or subtypes of pathogens requires a well conserved antigen. Identification of protective epitopes by screening a peptide library against sera or PBL from infected subjects! GenOMICS TranscriptOMICS ProteOMICS Antigen Discovery Using proteomics approaches to screen for "new' antigens • Stage specific expression • Use infected cells to find vaccine epitopes presented on infected cells Data mining for vaccine candidates Advantages • Access to every antigen • Non-cultivable can be approached • Non abundant antigens can be identified • Antigens not expressed in vitro can be identified Disadvantages • Non protein antigens like polysaccharides, glycolipids cannot be used Vaccine design Antigen Target +/- Adjuvant? Live vaccines Usually do not require adjuvants as they mimic natural infection and have high immunogenicity (naturally adjuvanted) Inactivated vaccines May require adjuvants, as they can lack pathogenic features of the microorganism responsible for triggering the immune response Vaccines with purified or recombinant antigens Usually require adjuvants, as they often have low immunogenicity owing to a lack of natural innate immune triggers Examples of Vaccines with intrinsic Adjuvants Give examples of Live attenuated veterinary vaccines produced by the NVI Examples of vaccines combined with adjuvants Give examples of inactivated or subunit veterinary vaccines Adjuvant Selection Considerations Vaccine Approach • Added value , compatible Type of immunity required • Antibodies and/or CD4 and/or CD8 Population to vaccinate • Infants, adolescents, elderly Healthy or diseased ? Vaccine design and characterization In Vitro Preclinical RO development Correlate of Protection (COP) ? Immunological Parameters that Correlate with Protection • COP: infection, disease, transmission Antibodies and/or T cells • If the immunologic COP is validated: Preclinical development focused on demonstrating the type of immunity required • If no COP identified: Preclinical development required to evaluate multiple immunological parameters. An ICP is a variable immune response that is statistically associated with protection Mechanistic correlate of protection (mCoP): directly responsible for protection and Non-mechanistic correlate of protection (nCoP): that is easy to measure but which may only be a substitute for an mCoP that is unknown or difficult to measure. If an infection is uncommon or deadly, such that an efficacy trial is not feasible or ethical, a CoP may yet enable licensure of a vaccine, and once established, a CoP will allow bridging from one vaccine preparation to another. In addition, a CoP may be absolute, i.e. there is a threshold value above which protection is certain, or Relative i.e. higher values are quantitatively more protective than lower values but there are occasional failures even at high levels and occasional protection at lower levels. • Development of Read-outs Immunogenicity Antibodies (serum, mucosal....) • Functional: neutralization, opsonization etc.. • Binding antibodies: ELISA T cells • ICS (intracellular cytokine staining), ELISPOT Efficacy Titration of viral or bacterial load (culture or molecular assays) If relevant animal model exists recapitulating the human pathogen of infection • Characterization of disease symptoms or pathology. adaptive immunity CD8+ T-cell B-cell Antibodies mustration courtesy of GSK Preclinical In Vivo Expermentaion Preclinical Studies ☂ Experimental designs require: Justification of immunological read-outs & sample size based on statistical criteria Approval by animal ethics committee ☂ Requirement for good scientific (GSP) or good laboratory practices (GLP), defined in medical product development regulations, for preclinical laboratory studies which includes Study conduct, personnel, facilities Equipment, written protocols, operating procedures, study reports System of quality assurance oversight Immunogenicity Studies ☂ Characterization and quantification of the immune response induced by the candidate vaccine antigen. Choice of antigen to be justified • Humoral responses (antibodies). • Cellular immune ( T cells). Choice and justification for the need of an adjuvant • At minimum compared to unadjuvanted & Alum formulations ☂ Selection of multiple parameters to improve immunogenicity: Route of administration Number of doses Demonstration of dose range effect "Relative" dose of vaccine components ☂ Insure consistency of vaccine lots. Pre-clinical Evidence for HPV Vaccine Design Animal models (COPV, ROPV...): demonstrate importance of anti-LI antibodies for protection against infection. "Virus Like Particles" VLP shown to be immunogenic Important target for viral neutralization Induce an efficient immune response capable of protecting mucosa from infection, following systemic immunization Protection against virus challenge following vaccination with L1 • Passive transfer of anti-L1 Ab can protect PV challenged animals Recombinant L1 protein: • Major surface protein of HPV • Self-assemble into Virus Like Particles: Resemble intact viruses Established a key role for antibodies: • Induction of neutralizing antibodies against the structural capsid protein L1 should prevent/reduce HPV infection and associated lesions. Characteristics of Good Animal Model • Prediction the protection in humans • Reproduce infection, pathology and/or clinical symptoms • Ideally use the same strain of pathogen that infections humans, if not species specific pathogens. Model Attributes and Limitations ☂ Human pathogen infection & disease symptoms • Ex :HBV / chimpanzee, HSV / guinea pig , RSV / cotton rats, influenza / ferrets, rotavirus /gnotobiotic pis... ☂ Human pathogen infection without disease symptoms • Ex :B. pertussis / mice, RSV / mouse, influenza / mouse & dengue virus/ non-human primates.... ☂ Non-Human Pathogen (clinical symptoms similar to humans) • Ex :SHIV or SIV / non-human primates, gpCMV /guinea pig, bRSV /cow-calves... Influenza • • • The main correlate of influenza vaccine efficacy is HI titer: antibodies that block influenza agglutination. An HI titer of 1:40 is associated with reduction in the risk of contracting influenza infection or influenza disease (De Jong 2003) Both antibody and T cell responses contribute to protection against seasonal influenza (McElhaney etal., 2009). Influenza Challenge Models Animal models (mice, ferrets, and guinea pigs) provide important information about vaccine immunogenicity & correlates of protection. • Vaccine effects included reduced viral loads in URT and lungs, lower morbidity and less lung pathology. Ferrets most appropriate model for efficacy studies: Susceptibility to infection with unadapted human influenza virus isolates Efficiency in transmitting influenza virus Clinical signs of disease similar to human influenza disease. Toxicology Evaluation : Why ? Tox studies evaluate the local tolerance and potential systemic toxic effects following vaccination Vaccine = combination of agents (antigen, adjuvants, carrier): potentially toxic Local effects: pain, swelling & redness at the injection site Systemic effects: fever, body weight, ophthalmology, clinical and morphological pathology. Objective of Toxicology Studies ☂ Demonstrate the candidate has an acceptable safety profile • Antigen & Adjuvant components ☂ Demonstrate reversibility of any potential effects. ☂ Key Evaluations • Macroscopic • Organ weight • Microscopic observations: Histopathology • Serological anomalies • Vaccine Immunogenicity ☂ Adapt clinical study monitoring, if warranted. • Reproductive Toxicity studies • Key Evaluations — Female fertility — Development of fetus (teratogenic effects) — Post-natal development — Vaccine Take • Required for vaccines intended for women of childbearing age. • When: — Parallel with Phase Ill clinical trials. — Conducted prior to studies enrolling pregnant women Thanks! Questions? “Vaccinology and Immunotherapy” Sadam M. (DVM, vaccinologist) University of Gondar June, 2023 Early phase s: R&D Postlicensure studies: impact studies, safety studies, new indications Vaccines Clinical vaccine developme nt: Phase-I, Phase-II, and Phase-III Preclinical developmen ts: safety, immunogen icity & efficacy studies Preliminary trial: a clinical trial that is not intended to serve as a pivotal trial. They are usually conducted to obtain information on the safety and immunogenicity of candidate vaccine formulations and to select the formulation(s) and regimen(s) for evaluation in pivotal trials. They may also serve to inform the design of pivotal trials (e.g. by identifying the most appropriate populations and endpoints for further study). On occasion, a preliminary trial may provide an initial evaluation of vaccine efficacy. New Candidate Vaccine: is a vaccine that is taken in national regulations to be separate and distinct from other candidate and licensed vaccines. Examples of new candidate vaccines include but are not limited to: a vaccine that contains a new antigenic component (i.e. not previously used in a licensed vaccine); a vaccine that contains a new adjuvant; a vaccine that contains antigen(s) ± adjuvant(s) not previously combined together in a vaccine; a vaccine with the same antigenic component(s) ± adjuvant as a licensed vaccine that is PRODUCED BY A DIFFERENT MANUFACTURER (including situations in which seed lots or bulk antigenic components used to make a licensed vaccine are supplied to other manufacturers for their own vaccine production). Non-inferiority trial: aim to demonstrate that the test intervention is not worse than the reference intervention by more than a small pre-specified amount known as the non-inferiority margin. In non-inferiority trials it is assumed that the reference intervention has been established to have a significant clinical effect (against placebo). Pharmacovigilance: encompasses the science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other possible drug-related problems Pivotal trials: pivotal clinical trials provide the major evidence in support of licensure. Posology: the vaccine posology for a specific route of administration and target population includes: the dose content and volume delivered per dose; the dose regimen (i.e. the number of doses to be given in the primary series and, if applicable, after the primary series); the dose schedule (i.e. the dose intervals to be adhered to within the primary series and between the primary series and any further doses). Post-licensure safety surveillance: a system for monitoring AEFIs in the post-licensure period. Protocol: a document that states the background, rationale and objectives of the clinical trial and describes its design, methodology and organization, including statistical considerations and the conditions under which it is to be performed and managed. The protocol should be signed and dated by the investigator, the institution involved and the sponsor. Randomization: In its simplest form, randomization is a process by which n individuals are assigned to test (nT) or control (nC) treatment(s) so that all possible groups of size n = nT + nC have equal probability of occurring. Thus, randomization avoids systematic bias in the assignment of treatment. Responder: a trial subject who develops an immune response (humoral or cellular) that meets or exceeds A PREDEFINED THRESHOLD VALUE USING A SPECIFIC ASSAY. This term may be applied whether or not there is an established ICP and when the clinical relevance of achieving or exceeding the predefined response is unknown. Sponsor: the individual, company, institution or organization that takes responsibility for the initiation, management and conduct of a clinical trial. The sponsor of a clinical trial may not be the entity that applies for a license to place the same product on the market and/or the entity that holds the license (i.e. is responsible for postlicensing safety reporting) in any one jurisdiction. Superiority trial: a trial with the primary objective of demonstrating that a test group is superior to a reference group on the basis of the primary endpoint. In the context of vaccine development the primary endpoint may be a safety parameter (e.g. occurrence of a specific type of AE), a clinical condition (e.g. occurrence of a specific infectious disease) or an immunological parameter (e.g. a measure of the immune response to one or more antigenic components of the vaccine). Key Principles of Vaccine Clinical Development Common principles guide the development of any vaccine candidate But each vaccine follows a unique developmental path depending on characteristics such as: – the type of vaccine (live/killed/subunit/DNA/peptide) – disease epidemiology – target population – and the availability of a pre-existing vaccine No harm principle Vaccines target usually healthy population, often infants or children Target population may have specific characteristics Vaccine effect can vary e.g. high malaria prevalence, nutrition, health status Vaccine effect can vary because of variation in prevailing disease — different vaccine may be needed (eg Malaria caused by Plasmodium falciparum - Plasmodium vivax) Vaccine schedule is adapted to population: concomitant medicines or vaccines, disease pressure Good Clinical Practice (GCP) guides development "Good Clinical Practice (GCP) is an international ethical and scientific quality standard for designing, conducting, recording and reporting trials that involve the participation of human subjects. Compliance with this standard provides public assurance that the rights, safety and well-being of trial subjects are protected, consistent with the principles that have their origin in the Declaration of Helsinki, and that the clinical trial data are credible" ICH.org The 13 principles of GCP 1. Clinical trials should be conducted in accordance with the ethical principles that have their origin in the Declaration of Helsinki, and that are consistent with GCP and the applicable regulatory requirement(s). 2. Before a trial is initiated, foreseeable risks and inconveniences should be weighed against the anticipated benefit for the individual trial subject and society. A trial should be initiated and continued only if the anticipated benefits justify the risks. 3. The rights, safety, and well-being of the trial subjects are the most important considerations and should prevail over interests of science and society. 4. The available nonclinical and clinical information on an investigational product should be adequate to support the proposed clinical trial. 5. Clinical trials should be scientifically sound, and described in a clear, detailed protocol. 6. A trial should be conducted in compliance with the protocol that has received prior institutional review board (IRB)/independent ehics commtittee (IEC) approval/favourable opinion. 7. The medical care given to, and medical decisions made on behalf of, subjects should always be the responsibility of a qualified physician or, when appropriate, of a qualified dentist. 8. Each individual involved in conducting a trial should be qualified by education, training, and experience to perform his or her respective task(s). 9. Freely given informed consent should be obtained from every subject prior to clinical trial participation. 10. All clinical trial information should be recorded, handled, and stored in a way that allows its accurate reporting, interpretation and verification. 11 . The confidentiality of records that could identify subjects should be protected, respecting the privacy and confidentiality rules in accordance with the applicable regulatory requirement(s). 12. Investigational products should be manufactured, handled, and stored in accordance with applicable good manufacturing practice (GMP). They should be used in accordance with the approved protocol. 13. Systems with procedures that assure the quality of every aspect of the trial should bé implemented. Phases of Vaccine Development • • • • Implemented License d Phase 3 Phase 2 Phase 1 Pre-clinical On average 10-15 years Highly pyramidal For each success there are many failures Failures could occur at any stage: preclinical, P1, P2, P3, and postlicensure (e.g. Rotashield licensed in 1998 in the US, withdrawn in 1999 for being associated with intussusception leading to recollection of all distributed doses) This postulate was the first framework for identifying a cause of a disease. Koch’s postulates are based on inductive reasoning and state that an organism is causal if: It is present in abundance in all cases of the disease but not in the absence of the disease. It does not occur in another disease as a fortuitous and non-pathogenic parasite, It is isolated in pure culture from diseased animal, is repeatedly passaged, and induces the same disease in other animals Limitations of Koch’s postulates •Koch’s postulates were too difficult to satisfy because it is a rigid framework for testing the causal importance of a microorganism. •It was based on imperfect knowledge of Causation: MO were assumed to be the sole causes of diseases Not applicable for non infectious Diseases Ignored multifactorial etiology & the influence of environmental factors, As a result, A more cosmopolitan theory of cause was needed. Steps in Koch’s Postulates 1) The suspected pathogen is found in sick animals but not in healthy ones. 2) The pathogen is able to be grown in a pure culture in the laboratory. 3) The laboratory cultured pathogen is injected into the body of a healthy animal. The healthy animal develops the same disease that was seen in the first host animal. 4) The pathogen is recovered from the second animal and is the same as the original pathogen. This method is the standard for determining the identity of a disease-causing pathogen. Koch discovered the cause of anthrax (Bacillus anthracis), tuberculosis (Mycobacterium tuberculosis), and cholera (Vibrio cholerae) using this approach. Phase I, first-in-man studies refer to the first administration of a vaccine candidate to humans. The primary objective is to reactogenicity evaluate the safety and Injection site reaction Pain, erythema, swelling Systemic reaction Fever, anorexia, fatigue, headache, muscle ache, joint pain The secondary objective is collection of immune response. Often times, the dose, immunization schedule and mode of vaccine administration (DI, MI, ...) are also assessed. First-in-man Phase I studies are usually small trials in healthy, immunocompetent naïve adults who are at low risk of acquiring a vaccine-relevant infection (determined by serology, exposure, and travel history). Based on results of adult studies (referred to as Phase Ia trials), Subsequent Phase I studies may be conducted in different age or population groups closer to the target population To assess possible differences in dose, safety, vaccine schedule, or route of administration. Such subsequent studies in different geographies and populations are referred to as Phase Ib. RTS, S/GSK [The WHO Regional Office for Africa (WHO/AFRO) Malaria Vaccine Implementation Programme (MVIP)] underwent Phase I testing first in malaria-naïve (USA) adults And then in malaria-exposed adults (Mozambique, Kenya, Tanzania Africa), Followed by trials in 1-11-year-olds and finally in infants residing in malaria- endemic regions. Cervarix was tested in 18-30-year-olds in USA who were seronegative for HPV DNA to assess the monovalent and bivalent formulations, while another Phase I/II study was conducted in 18-30- year-old women positive for HPV 16 or HPV 18 DNA. Phase I trials are usually open-label and non- randomized But, it is possible to conduct randomized controlled trials (RCTs) in which a placebo or a vaccine against a different disease is used as a comparator. To control for bias, such a study can be single-blinded or double-blinded. The practice of using bedside formulations wherein the vaccine antigen and adjuvant are mixed just prior to immunization is frequently followed in Phase I trials. This can allow the vaccine developer to test more than one adjuvant with the same vaccine antigen without having too many vaccine formulations. It is recommended that the Phase I study site be located within or in the vicinity of a tertiary care hospital for safety reasons With Medical doctors trained to GCP in Clinical Trials Able to take care of an anaphylactic shock After immunization, the need for day-care observation is guided by the need for monitoring adverse events. Tolerability and reactogenicity due to the vaccine or the process of vaccination is the major safety outcome evaluated in a Phase I trial. To ensure comparability of safety data within and across clinical trials, it is recommended to follow a standardized approach of data collection, analysis, and reporting. For healthy volunteer vaccine studies, the toxicity grading scales provided by the USFDA and the case definitions developed by the Brighton Collaboration for specific solicited events are recommended as standard references. Clinical safety laboratory testing (e.g., hematology, biochemistry, urinalysis) also forms a part of the safety data that are collected at baseline, at defined intervals, and at the end of the trial. The immunogenicity assays should preferably be validated and performed under Good Clinical Laboratory Practice (GCLP). The immunological data can be presented as recommended in EMA guidelines: The percentage of “responders” or individuals who “seroconvert” [with 95% confidence interval (CI)]. Responders are either individuals developing an immune response above a certain threshold level or those who reach a certain minimum increment in antibody concentration/titer after vaccination. These increments may or may not indicate protection. These criteria should be defined in the protocol prior to study initiation. Live attenuated/killed vaccines pose concerns about possible shedding of infectious agents, transmission to contacts, and a possible reversion to a more virulent state. Therefore, volunteers of such Phase I trials require intensive investigations in closely monitored clinical settings, including evaluation for any clinical signs of infection. The extent, route, and duration of shedding vary with the type of vaccine and route of administration. Immunocompromised persons should avoid contact with such vaccinees for a certain time period to avoid contracting an indirect infection. A candidate vaccine should proceed to Phase II clinical evaluation after achieving a satisfactory outcome in Phase I studies in terms of both safety and immunogenicity. The transition from a controlled clinical setting to field evaluation incurs much greater monetary investment, hence stringent go/no-go criteria are observed by the developers. • • • • • • Clinical Trials: Phase Il POC (Proof of Concept /FeasibiIity) Age de-escalation: adults adolescents /children /toddlers /infants Sample size: 50 — 200 individuals /group Select and justify final dose and formulation Further evaluate the safety profile Might evaluate the most efficient vaccination schedule (Idose, 2-doses ...) Might evaluate most efficient route of vaccination The objective is to identify the vaccine preparation, optimal dose, and schedule to be taken up for confirmatory Phase III trials. These studies have the desired statistical power and a defined sample size, to provide a clinically meaningful outcome on the safety, immunogenicity, and efficacy endpoints. Phase II studies assess the impact of multiple variables on immune response, such as age, ethnicity, gender, and presence of maternal or pre-existing antibodies (in infants) and evaluate: Age of first administration of vaccine [e.g., during the development of RotarixTM, the age of first administration varied between countries depending on factors such as nutrition status, influence of maternal antibodies, and Expanded Program on Immunization (EPI) schedule]. Number of vaccine doses (For RotarixTM, two and three doses were studied in Phase II studies, while for GardasilTM the dosing schedule remained standard throughout clinical development). Sequence or interval between vaccine doses, route of administration, duration of immunity, potential need for booster immunizations, and qualitative aspects of the immune response. In a Phase II trial of GardasilTM, incidence of persistent infection associated with HPV 6, HPV 11, HPV 16, or HPV 18 decreased by 90% in women allocated active vaccine compared with those allocated placebo over 36 months follow-up. During Phase II trials, if an immune correlate of protection is identified, it facilitates the interpretation of results in future clinical studies with immune response as end points. Phase II studies recruit hundreds to thousands of subjects A large population allows to conclude with confidence that the vaccine candidate is safe, sufficiently immunogenic, and maybe protective The study population can comprise adults, adolescents, children, infants, or even pregnant women, depending on the study objective However, for a vaccine being developed for infants a step-down approach is usually followed wherein trials are conducted sequentially in adults, adolescents, children, and infants. Additionally, different populations can be enrolled in different countries to reduce costs, save time, and still collect meaningful data to be able to proceed to the next phase of development (The most recent example is of the vaccine developed for cervical cancer (GardasilTM), in which case Phase II studies were conducted in both female and male populations aged 9-25 years.) In randomized controlled designs, the investigational vaccine is tested against either a placebo or another vaccine. These studies are usually conducted in community-based study sites where controlled trials are feasible, i.e., in places where information about the population (demography, migration, sex ratio, disease patterns, etc. and the pathogen/disease of interest (different strains of pathogen, disease severity and pattern, seasonality) is available. Depending on the type of vaccine being studied, the study area can differ (e.g., for GardasilTM the target population was young adults and adolescents, therefore the sources of the study population were colleges, universities, and their surrounding communities, while rotavirus vaccine studies enrolled children and infants from communities, hospitals, and polyclinics.) Phase II studies designed to report partial efficacy of a vaccine candidate and are conducted in settings of high incidence of the infectious disease so as to be able to provide a good readout of the end point. For example: two similar Phase IIb studies were conducted with RotarixTM in Latin America and Singapore to evaluate the safety, immunogenicity, and efficacy of different dose concentrations. Both studies were placebo-controlled, proceeded in parallel with almost similar sample sizes, and achieved good seroconversion rates, but the Latin America trial also demonstrated protective efficacy against two serotypes of rotavirus. As described for Phase I studies, the humoral and CMI response to the immunogen(s) in the vaccine candidates should be evaluated. The mode of protection of the vaccine guides the measurement of immune response. With RotarixTM (oral), serum IgA antibody concentration was monitored, while in the case of GardasilTM (parenteral), serum IgG was measured to determine the seroconversion rates Rarely, Phase II studies can be the definitive study for licensure with immune markers as outcomes For example, the meningococcal C conjugate (MCC) vaccine was licensed on the basis of serological correlates of protection without efficacy data in United Kingdom The type of adverse events (solicited, unsolicited, laboratory) collected during Phase II trials and the mode of collection (through visits to clinics and subject diary cards/questionnaires) are similar to Phase I trials. However, as Phase II studies are statistically powered and better designed, they are able to provide meaningful differentiation in terms of distribution and differences in adverse events between groups. In some cases, Phase II data may also provide information regarding specific adverse events that should be evaluated more carefully in larger Phase III trials. Phase II trials can also provide preliminary information on protective efficacy through human challenge studies, wherein healthy participants are deliberately infected with the pathogen. Such studies are commonly referred to as Phase IIa studies and are appropriate only for selected diseases wherever it is scientifically and ethically justified, where the pathogen does not cause lethal infection and is not resistant to available treatment, and a complete and successful cure can be obtained. Human challenge studies have been conducted to test the preliminary efficacy of vaccine candidates against malaria, typhoid, and cholera. In case of RTS, S, investigators conducted multiple combined Phase I/IIa studies to assess preliminary efficacy. Such studies offer rapid assessment of the usefulness of a vaccine candidate in a limited number of subjects, thereby preventing the unnecessary exposure of thousands of individuals, mostly children and infants, in large Phase II/III trials to a potentially ineffective vaccine. It thus allows quicker vaccine development and serves as a go/no-go step for advancing development. Pivotal Phase III trials, essential for registration and approval to market of a vaccine, assess the effect of the final formulation. These trials are designed to evaluate efficacy and safety. Vaccine Efficacy (VE) is defined as the percent reduction in incidence (of disease or infection) among the vaccinated. If incidence of disease in unvaccinated subjects is “Iu” and in vaccinated subjects is “Iv”, then the VE is calculated as: (Iu-Iv/Iu) × 100% = (1- Iv/Iu) × 100% = (1-RR) × 100% Iu = incidence in unvaccinated population Iv = incidence in vaccinated population RR = relative risk Occurrence of disease is the most common endpoint; however, the trial may be based on other clinical end points, such as immunological correlates of protection. Clinical Trials: Phase Ill Pivotal Clinical Trials • Large clinical trials which could involve thousands of individuals • Demonstrate in target population of Immunogenicity /Efficacy: Demonstrate efficacy: vaccine prevents infection /disease Demonstrate immunogenicity (e.g. correlate of protection) • Further evaluate the safety profile large safety database (Health Authorities) • Co-administration with licensed vaccines /standard of care vaccines • Manufacturing process evaluation : Immunological bridge from lots used in Phase Il (-III) trials to final commercial scale lots Demonstrate consistency of 3 successive lots produced at industrial scale Phase III trials are large-scale clinical trials enrolling thousands of subjects from the target population. They are conducted in “field” conditions that are similar to future routine use. Incidence of disease in the study population impacts the sample size: a low incidence means that large numbers of subjects are required to estimate vaccine efficacy in comparison to the numbers needed if disease incidence is greater. In diseases where an immunological end point correlates with clinical protection, it can be used as a primary efficacy end point, and smaller sample sizes often suffice RCTs are considered the “gold standard,” where participants are randomly allocated to receive either the investigational or the control vaccine (placebo, different vaccine, or nothing). A prospective RCT controls variables, prevents bias, and maximizes the chances of detecting a difference between the investigational vaccine and control. Superiority trial designs are employed if there is currently no effective vaccine for the disease For comparisons against existing vaccines, a non inferiority trial is planned to demonstrate that the relative risk of disease or infection with the new vaccine is not greater than the available vaccine Vaccine efficacy can also be studied through group randomized trials. Such group/cluster randomized trials study the indirect protection (herd immunity) offered by the vaccine in a community However, for licensure studies, individual randomization studies are preferred because if the product is not giving any direct protection, it is unlikely to have any indirect effect. Further, safety evaluations are difficult to conduct in cluster randomized trials Secondary attack rate study or household contact study (can be randomized): These are pre-exposure cohort trials for infections with a high secondary attack rate The unit of intervention may be an individual, family, or community The indirect effect is the difference in the outcome in an unvaccinated individual when living in a vaccinated community or living in a comparable unvaccinated community Such clinical trials are not done for vaccine licensure as yet but may become common in the near future Observational cohort studies May be considered where: a RCT is not ethically justified the clinical end point requires long- term follow-up (e.g., hepatitis B vaccination in neonates) the number of individuals is too large to follow up It should be of importance to public health and should also be clinically important. Often the evaluation of protective efficacy focuses on the ability of the vaccine to prevent clinical disease! However, if an organism causes a range of infections (e.g., from mild infection to severe disease), then the primary end point can be carefully selected in accordance with the proposed indication. Ways to demonstrate efficacy Clinical endpoint Immune response endpoint (ICP) Animal models Vaccine efficacy is normally assessed on the basis of a single end point (e.g., severe gastroenteritis in Phase III study of RotarixTM) However, a composite efficacy end point can also be studied : e.g., incidence of genital warts, vulvar or vaginal cervical intraepithelial neoplasia (CIN), or cancer, or cancer associated with HPV type 6, 11, 16, or 18 were composite end points for evaluating GardasilTM. While selecting an end point, it is important to note that the more serious the end point, the lower is its incidence, which in turn lowers the probability of studying the impact of a vaccine The primary end point should be carefully chosen because that will generally determine the size of the trial The remaining outcomes can be studied as secondary endpoints. To accurately identify the end points in clinical protection studies, confirmation of cases through laboratory methods, antigenic detection, and the clinical picture is necessary to support a clinical case definition Case definitions for the trial endpoints should be clearly defined in the protocol e.g., during Phase III study of GardasilTM, investigators were given standard protocols for anogenital examination, conducting colposcopy, and classifying cervical samples on a standard scale Similarly, for the RotarixTM trial, standard case definitions were used for defining an episode of severe gastroenteritis The validity of the diagnosis is most important for evaluation of efficacy or safety If no well-validated methods for establishing infection and/or progression of infection exist during the period of prelicensure clinical development, then experimental laboratory methods can be used The sensitivity, specificity, and reproducibility of the methods used to ascertain a case are included in the study reports In clinical trials where prevention of disease is used as an endpoint, considerable efforts should be made to establish the immunological correlate of protection (e.g. HVB) To determine immunogenicity, serological data are usually collected from a subset of the immunized population at predefined intervals and from persons classifiable as vaccine failures In the prelicensure studies, it is recommended to enroll approximately 3000 subjects. However, where Phase III studies are designed with safety as the primary end point, huge sample sizes are seen, e.g., >37000 subjects were enrolled in a 7-valent pneumococcal conjugate vaccine study, while for Rotarix™ and RotaTeq™ ~63,000 and ~70,000 infant subjects, respectively, were assessed to detect the risk of intussusception. “Phase IV trial” or “post-marketing surveillance study (PMS)” Phase IV trials involve the safety surveillance (pharmacovigilance) over a much larger patient population and a longer time period. Assesses effectiveness of vaccination programs Assessment whether the vaccine works under normal/field use. Phase IV studies may also be REQUIRED by regulatory authorities, For example, on certain population groups such as pregnant women, HIV (drug interactions), ...or May be undertaken by the sponsoring company for finding a new market for the drug/vaccine Harmful effects discovered by Phase IV trials may result in a drug or vaccine being no longer sold, or restricted to certain uses (E.g. Rotashield® and the recent Dengvaxia®) Clinical Trials: Phase IV Post-Authorization Clinical Trials • Trials performed post-licensure could be: Requested by Regulatory Authorities requests as conditional for vaccine's approval -Y Regulatory Commitments Performed for label updates (e.g. age extension, coadministrations, long-term antibodies persistence, new target populations ...) Unlike drugs, which are given to patients, vaccines are received by healthy individuals, thus the safety margin should be very high As vaccines have to be stored under refrigeration, there are always logistical challenges during clinical trials considering that Phase II and Phase III are “field studies” As healthy children also receive immunization under the national program, the trial design gets complicated due to the possibility of interference during co-immunization The compatibility of the adjuvant with the vaccine antigen and the quality and stability evaluation of antigen/adjuvant formulation are important aspects of clinical development. The immune response primarily measured during early stages of vaccine development (Phase I/II) should evaluate: amount, class, subclass, and function of each specific antibody Relationship between functional and nonfunctional antibody assays Kinetics of immune response such as lag time for onset, antibody persistence, seroconversion rate, and induction of immune memory Components of the immune response according to mode of delivery [whether immunoglobulin A (IgA) or immunoglobulin G (IgG)] Quality of the antibody response: specificity and/or epitope recognition and avidity Potential for formation of cross-reactive antibodies or immune complexes Immunological factors that might affect the humoral immune response as preexisting antibodies (including maternal antibodies). Cell-mediated immune (CMI) response and the possibility of immune interference and/or cross-reacting immune responses when vaccines containing more than one antigen or two or more vaccines are coadministered, especially to children and young infants with immature immune systems These studies are conducted in healthy individuals, thus, SAFETY remains to be the utmost priority through out the development The disease endpoints (preventable infectious disease for e.g.) could be so rare, for this reason, pivotal studies are very large (involving thousands of subjects) Complexity of enrolling subjects (why?) Requirement of cold chain maintenance The studies are community-based rather than hospitalbased Long manufacturing lead times for clinical trial lots Vaccines HAVE to be safe! • The most effective tool for improving public health • Given to healthy individuals (from babies to elderly) • No immediate obvious health benefit for vaccinated individual • A high standard of safety is expected • Acceptable risk is minimal Approval stage Pre-clinical and clinical data to support approval Post-clinical phase: Phase 4: Effectiveness of the vaccination program Post marketing surveillance and program evaluation Assessment whether the vaccine works under field condition while phase 3 involves clinical trial to measure efficacy under controlled setting Vaccine Development Process: summary Early Stages SAFETY SAFETY Efficacy Effectiveness Development, Evaluation, & Validation Post-licensure PROGRAM IMPLEMENTATION Antigen identification & discovery Adjuvant discovery & selection Ag/adj. Physical & Chemical characterization Formulation PRECLINICAL STUDIES CLINICAL STUDIES Pharmacokinetic s Safety/Toxicity Studies Phase-I to III Mechanisms of action Immunogenicit y studies Efficacy studies Discussion with regulatory bodies Filing application and Registration Post-marketing surveillance (Phase IV) Impact studies Thanks! Questions??