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Co-Delivery and Formulation of Adjuvants for HIV Vaccines



Co-Delivery and Formulation of Adjuvants for HIV Vaccines

Fast Track proposals will be accepted Number of anticipated awards: 3-4 Budget (total costs, per award): Phase I: up to $300,000/year for up to 2 years; Phase II: up to $1,000,000 per year up to 3 years



The RV144 Phase III Thai trial, which tested the heterologous prime-boost combination of two vaccines: ALVAC® HIV vaccine (prime) and AIDSVAX® B/E vaccine adjuvanted with Alum (boost), showed limited 31% protective efficacy and revealed the need for novel and more potent vaccine formulations. Co-delivery of adjuvant/immunomodulators with HIV antigens have the potential to modulate the type, quality and durability of antigen-specific immune responses through a variety of mechanisms that include the induction of regulatory T cells or by altering the profile of the pathogenic lymphocyte response (e.g., Th1 to Th2 or vice versa). Significantly, induction of protective and long lasting durable immune responses, activation of germline B cells along with enhanced magnitude and breadth of antibodies that can be harnessed by optimal HIV antigen-adjuvant/immunomodulators/Toll-like receptor agonists (TLR) formulations would aid in the rational design of a safe and effective preventive HIV vaccine. More recent efforts have focused on testing adjuvant formulations that can boost the immune response and generate broadly neutralizing antibodies to HIV-1 Env. Despite these efforts, significant challenges remain towards achieving optimal and effective immunogen/adjuvant formulations for an efficacious HIV vaccine.

While ongoing new strategies and efforts for developing effective HIV vaccine have predominantly focused on design of new HIV immunogens and targets, an understudied area of investigation is with studies involving co-delivery and formulation of HIV immunogens with adjuvants. As such, several challenges remain, including poorly understood and variable humoral and cellular immune responses in preclinical and clinical setting, lack of consistent tier 2 broadly neutralizing antibodies (nAbs); maintenance of Env immunogenicity; selection of optimal inoculation sites and trafficking to lymphatics; stability of the incorporated and/or co-delivered antigens and Env neutralizing epitopes in select adjuvant formulations; induction of mucosal immunity and long-term maintenance/durability of the immune response. Moreover, access to promising new/proprietary adjuvant systems developed by commercial organizations, development of effective combination of adjuvant formulations and public-private partnership is highly desirable and warranted for HIV vaccine development. While alum-based adjuvants and variations of oil-in-water approaches have been tested with other non-HIV recombinant protein immunogens, the results obtained from other immunogens, which are generally more stable and less glycosylated than Env protein, have been difficult to extrapolate to HIV vaccines. Finally, the empirical basis of studies and the large inter-laboratory variations in antigen/adjuvant mixture formulations and protein stability assays used to characterize these mixtures further limits the usefulness of these data for HIV vaccine research.

Project goals

Co-delivery of adjuvants with antigens coupled with immunogen design are not mutually exclusive and should converge to accelerate the development of safe and effective adjuvanted HIV vaccine candidates that are capable of effective B/T-cell activation, enhanced antibody avidity or broadening of effector immune responses while minimizing reactogenicity and preserving the protective immune responses against HIV. The primary goal of this contract solicitation is to support, accelerate and advance early stage and/or pre-clinical development and optimization of a promising HIV antigen-adjuvant formulation or select combination-adjuvant(s) for co-delivery/co-administration for a preventative HIV vaccine.

Phase I activities may include:

Developing optimal parameters/conditions for HIV protein antigen(s) and adjuvant co-formulations

• Evaluating formulations with immunomodulatory agents such as mineral salts, microbial products, emulsions, cytokines, chemokines, polymers, liposomes, saponins, carbohydrate adjuvants, TLR agonists etc.

• Developing, harmonizing all relevant analytical assays and testing methods for physicochemical, biophysical and functional/potency characterization of antigen-adjuvant formulations and its individual components, as applicable

• Evaluating and screening compatibility of excipients, buffers, pH on adjuvanted antigen formulations and its performance

• Measuring the effects of these interactions using critical in vitro performance metrics and quality attributes related to vaccine adsorption, desorption, potency, antigen integrity and stability

• Developing and optimizing novel adjuvant combinations by admixing previously known individual adjuvants, including characterization of adjuvant combinations previously shown to enhance immune responses synergistically and/or additively

Evaluating conditions for vaccine presentation as a two-vial system with bedside mixing and/or one vial co-formulation of adjuvanted antigen

• As appropriate, evaluating and comparing different adjuvanted formulations in small animal models, assess the influence of route of administration, delivery and dose-sparing capacity of HIV antigen-adjuvanted vaccines on the kinetics of immune response

• Conducting short term stability studies to generate baseline data on antigen-adjuvant formulations

• Testing for batch-to-batch reproducibility and consistency of adjuvanted formulations for manufacturing

Phase II activities may include:

Developing lead antigen-adjuvant formulation into an efficient, stable and reproducible formulation process

• Generating a pilot lot and/or scale-up studies based on optimized conditions that can subsequently lead to the production of clinical grade material in conformance with current Good Manufacturing Practices (cGMP)

• cGMP manufacturing processes for developing adjuvanted formulation

• Evaluating the performance, effectiveness, and toxicity of adjuvanted HIV vaccine candidates vs. soluble antigen in small animal models

• Evaluation of adjuvants in NHP studies

• Establishing quality assurance and quality control, methodology and development protocols for generation of HIV antigen-adjuvanted formulations for co-delivery

• As appropriate, collaborate and/or partner with different labs to harmonize inter-laboratory variations in antigen/adjuvant mixture formulations and for characterization and protein stability assays

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