The TPP and PDP are updated as the project prepares the planning for clinical Phase 1.  The PDP should include new information from the characterisation and process activities and data generated in pre-clinical studies.  It should also include details of the preparation for the Phase 1, First-in-Human (FIH) study,with its design (population, doses, schedule etc.) or a synopsis of the protocol.  It should also include other Phase 1 studies, if planned.  The Gantt chart and budget are updated.

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The developer could consider a formal evaluation by a patent attorney of the freedom to operate, with an opinion on risks.  The analysis of IP should further confirm or solidify what would be an acceptable intellectual property position, and IP strategy.  Further patent applications should be filed as appropriate based on emerging data.  Follow-up of applications already submitted and evaluation of patents in the field is needed.  

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The assays selected for quality control and characterisation are developed, together with target specifications, for identity, potency, purity, etc.  These quality parameters of the substance and the product are referred to a Bill of Testing (BoT), or Quality Target Product Profile (QTPP).

Note: the raw materials used for production of the substance and the product should be checked before being used in the lab.  This quality control procedure is mandatory for current Good Manufacturing Practice (cGMP) operations.  Certificates of Analysis of raw material must be collected and assays with target specifications selected for release.

The process is scaled up from lab-scale to pilot, at a scale calculated to generate sufficient material for toxicity studies and Phase 1 / 2 clinical studies.

MCB and WCB, or a combination of Master and Working Virus Seed Lot combined with a MCB and WCB of complementary host cells, are manufactured according to cGMP guidelines or equivalent quality level.  After determining feasibility of the pilot-scale process performed with cells from the WCB, vials are sent for release testing.

Standardised production runs at pilot scale (pre-GMP runs) will confirm feasibility and reproducibility.  Indeed, by demonstrating that repeated runs can be performed within certain ranges around the set-points for the relevant process parameters, the reproducibility of the process (or process steps) is established, as required for the pilot process according to GMP guidelines.  The variation obtained in parameters which are considered critical should be within the ranges tested at lab scale.  At the end of this Stage, the selected process now at pilot scale, can produce the right quantity of product with the correct quality (drug substance and contaminants) and, no further adjustments are required.  Also, at this stage additional information on Cost of Goods could be gathered based on the standardised pilot process.

At the end of this stage, the process is fixed for manufacturing of Phase 1 GMP material.  Later changes in the process can be required.  It will have to be demonstrated that the implemented process changes do not affect the product quality attributes (product comparability).  For TB vaccine candidates, later changes in the production process would likely need clinical bridging studies.

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Synopsis protocols should be prepared for any safety and toxicity studies required by the relevant National Regulatory Authorities (NRAs) (also refer to Function ‘Regulatory’).  At a minimum, this generally includes a local tolerance and repeat-dose toxicity study conducted under Good Laboratory Practices (GLP).  However, additional studies may be required depending on the vaccine candidate.  For example, genotoxicity and carcinogenicity studies may be required for novel vaccine adjuvants.  Early consultation with NRAs is recommended to ensure the proposed studies meet their expectations.

In case the NHP modelis used at Stage C, recording the occurrence of possible adverse events can add to the preclinical dossier and the safety profile.  While for NHP in particular registration of aspects of normal behaviour is also ethically pertinent,further assessment of local or systemic adverse events upon vaccine administration contributes to the establishment of a tolerability or reactogenicity profile.  Local adverse events may be semi-quantified by so-called Draize scores.  Systemic adversity can be supported by standard clinical chemistry and haematology measurements, while dedicated NHP centres have defined normal ranges for specific species or cohorts.  Beyond routine, imaging or specific sampling for assays may be integrated to address aspects of vaccine safety in the pre-clinical evaluation protocol.  While most typically, vaccine studies are using NHP that are immunologically naive to prior mycobacterial exposure, post exposure conditions should be considered for the sake of safety profiling of new vaccines aimed towards clinical application/evaluation inexposed BCG-primed and/or IGRA-positive populations.

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Taking advantage of the system validity of NHP and the vast range of specific and cross-reactiver eagents, NHP vaccine studies can be deployed for immunogenicity assessments in advanced  preclinical stages.  It can be opportunistic, however, to consider NHP studies not prior to but in parallel to early clinical phase testing.  As in other animal species, it is imperative to define in NHP a primary assay for detecting the administration or the take of the vaccine per se.  Depending on the ethical authority, a vaccine response may be required as a formal 'Go-No-go'-criterion before entering into infectiouschallenge. Anticipating the subsequent challenge with Mtb, however, it is advisable to extend the study plan in the vaccination phase with additional immune assays or sample collection for future retrospect analyses.  Either driven by specific hypotheses of protective immunity or by unbiased (hypothesis-generating) omics approaches, NHP samples from the post vaccination phase can be expected to contribute to our understanding of vaccine-induced host immunity against TB.  Especially if the candidate strategy proofs efficacious in the model, working back from protected phenotypes additional samples and assays shall add towards identifying correlates of protection and towards developing biomarkers, deployable either in future NHP studies (also adding to ethical refinement, reduction or replacement) or in support ofclinical vaccine evaluation.  In addition to adaptive immune parameters, NHP are suitable also for innate response assessments, while innate immunity may be trained by whole cell vaccines (in line with the innate training potential of BCG in the clinic) or induced by adjuvant or vector formulation.  Especially for subunit vaccination or putative revaccination strategies, macaque colonies that have received standard intradermal BCG immediately after birth are (being) established.  Of note, and while alternative administration routes (e.g. mucosalor intravenous) have demonstrated superior efficacy when using standard BCG, such efficacious strategies may serve as positive controls in study designs for candidate vaccine evaluation in NHP.  So far, such alternative delivery strategies have provided statistical correlates of antigen-specific Th1/Th17 function, antibodies and cytokine release in the airways as well as early systemic innate immune parameters.  Mechanistic studies in NHP suggest that both CD4- and CD8-expressing lymphocyte subsets contribute to protective immunity inmacaques.

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Though also the NHP model is not validated, it could be a valuable model for efficacy evaluation in stage C (see also “Animal Model Considerations), as a wide range of pathology, bacteriology, imaging and immunity analyses can be deployed for efficacy readout in fixed endpoint designs.  However, time-to-humane endpoint strategies are feasible but poised with some ethical concern and increased cost and standard measures of clinical chemistry and haematology for monitoring, for example systemic inflammation and loss of protein or infection-associated anaemia, appear more robust only when a higher dose challenge is applied, which has become an uncommon approach lately.  Typically, single low dose challenge with Mtb strain Erdman K01, available as standardized stocks from BEI Resources, is used for infectious challenge of NHP, either by aerosol inhalation or endobronchial instillation.  Also, a repeated limiting dose challenge model has been defined with infection occurring more as a stochastic event, to further support longitudinal readoutsof infection and immunity.  In concordance with what has been raised under functions 5 and 6 on safety and immunogenicity already, also for efficacy evaluation in NHP mycobacterial pre-exposure conditions (e.g. prior BCG vaccination, NTM exposure or 'latent' Mtb infection) should be considered.  Various experimental strategies, based on alternative dosing and/or delivery of BCG, have yielded prevention of infection (POI) and prevention of disease (POD) signals, which set an important mark on the dynamic range of NHPTB infection modelling.  Regarding the time response dynamic, various imaging approaches have been used in NHP vaccine studies.  Beyond conventional chestX-ray, many laboratories monitor TB over time by computed tomography (CT) either or not in combination with positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) or more experimental tracers to track the host response after infectious challenge.  Post infection sampling and immune response measurements should be considered for extended study designs, sinc ethey can support (diagnostic) biomarker studies or the investigation of protective immunity in the face of the intruding pathogen.

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Consultation with a Stringent Regulatory Authority (SRA, i.e. a regulatory body recognised to adhere to internationally accepted standards, notably those defined within the ICH) for formal advice will be most valuable prior to starting clinical development of a new TB vaccine. Data generated to this point are presented to the Authority, and advice is requested via specific questions. Topics for discussion and agreement with the regulatory agency usually include: (a) Manufacturing process and controls, characterisation of the antigen, release specifications for the MCB/WCB and drug substance/product and stability specifications. These discussions would include the choice of the relevant Quality Control and characterisation assays – especially for potency; (b) Pre-clinical and toxicology study programme; and (c) synopsis of protocol for Phase 1 and summary of clinical development plan.

Activities in Stage C are based around planning and preparation for FIH trial and subsequent Phase 1b trials that are designed to include target population individuals, in order to provide the data needed to support preparation and conduct of Phase 2 studies.

Community Engagement planning is a significant strategic process designed to build long-term relationships and working collaborations with the people most affected by TB disease.   Community engagement initiatives should be planned and implemented at all clinical sites where the studies will be conducted in preparation for the future studies and these initiatives will be ongoing through the entire development programme. They should include consultation over study design and dissemination of results to trial participants and the broader community. The communication of expected and unexpected outcomes is a significant part of this activity as well as general education about TB and vaccines.

First in Human (FIH) Phase 1 study design should be double-blind, randomised, controlled and dose-escalating to evaluate safety and immunogenicity of the investigational vaccine in a limited number of healthy, BCG naïve and, potentially, BCG vaccinated adults with no evidence of exposure to TB. Subsequent Phase1b studies will be designed and conducted in the target population in TB-endemic areas. At this stage the design of Ph1 and the CDP could be presented to NRA at a scientific advisory meeting, for more information refer to function ‘Regulatory’.

A study synopsis for Phase 2a studies to select a dose(s) for further development should be drafted.

The CDP will be updated to reflect any new relevant information that has become available from the pre-clinical programme and/or general advances in the field of TB vaccine research.

TB vaccine target population considerations

Adolescent/ adult vaccine: FIH studies could be planned to evaluate the safety and immunogenicity of the investigational vaccine in BCG naïve and BCG vaccinated individuals, who have no evidence of latent TB infection, sequentially in the same study. In addition, Phase 1b studies are designed to evaluate the safety and immunogenicity of the investigational vaccine in subjects from endemic areas who have evidence of latent TB infection.

Neonate/ infant vaccine: Phase 1b studies are designed to evaluate the safety and immunogenicity of the candidate vaccine in neonates in TB endemic areas. Study design is dependent on the vaccination strategy, BCG replacement or BCG boosting vaccine.  

Therapeutic vaccines: Phase 1b studies might not be required if safety and immunogenicity data are available from BCG vaccinated Mtb infected individuals. Proceed to Phase 2a (dose and regimen selection).

The assessment of safety is the primary objective of Phase 1 and 1b studies. An important aspect at this stage is therefore to define the safety endpoints for these studies.