Engineering kinetics of immunotherapies and vaccines
The dynamic progression of immune responses to infections & tumors points to the possibility of an optimal temporal window for immune modulation as a key parameter that could influence protective outcomes. Altering kinetics in an attempt to orchestrate an immune response in resonance with the bi...
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| Other Authors: | |
| Format: | Thesis |
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Massachusetts Institute of Technology
2024
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| Online Access: | https://hdl.handle.net/1721.1/154366 |
| _version_ | 1811072832402096128 |
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| author | Bhagchandani, Sachin Haresh |
| author2 | Johnson, Jeremiah A. |
| author_facet | Johnson, Jeremiah A. Bhagchandani, Sachin Haresh |
| author_sort | Bhagchandani, Sachin Haresh |
| collection | MIT |
| description | The dynamic progression of immune responses to infections & tumors points to the possibility of an optimal temporal window for immune modulation as a key parameter that could influence protective outcomes. Altering kinetics in an attempt to orchestrate an immune response in resonance with the biological rhythm of innate and adaptive immunity could have significant returns with respect to improved efficacy and decreased toxicity; all without necessitating the approval of new agents. In this thesis, we explored two distinct strategies to engineer immunotherapy and vaccine kinetics. We show how these kinetics can significantly impact cellular and humoral immune responses, and carried out detailed investigations into the underlying mechanisms that govern these temporal effects.
Firstly, imidazoquinolines (IMDs), small molecule agonists of Toll like receptor (TLR)-7 and/or TLR-8, are of great interest as potential anti-cancer therapeutics due to their ability to activate innate immune cells. Nevertheless, safe and effective systemic administration of these compounds in the clinic is an unsolved challenge due to dose-limiting toxicities, poor bioavailability, and severe immune-related adverse events upon intravenous administration. While attempts to deliver them via nanoparticle technologies have improved the potency of IMDs, achieving these outcomes while minimizing acute systemic inflammation has proven difficult.
Here, we developed a bottlebrush prodrug (BPD) IMD library as a tool to provide a detailed understanding of how the kinetics of drug release impacts safety and tumor immune stimulation. Cylindrical BPDs featuring antibody-like dimensions (~10 nm), coaxial PEG chains, and TLR-7/8 agonists linked through cleavable linkers along their backbone were synthesized using ringopening metathesis polymerization (ROMP). By tuning the cleavable linker molecular structure, IMD-BPD constructs were identified that allowed for potent stimulation of innate immune cells in tumors while avoiding systemic increases in inflammatory cytokines, reductions in white blood cell counts, or liver toxicity. These BPDs enabled significant reductions in tumor growth in syngeneic tumor models and improved responses to anti-PD-1 checkpoint blockade. Single-cell RNA-sequencing revealed that IMD-BPDs promote dendritic cell activation and reduce immunosuppressive macrophages in the tumor microenvironment, changes that free TLR7/8 agonists were unable to achieve.
Secondly, “extended dosing” of vaccines – immunization regimens that prolong exposure to antigen/adjuvant– has shown promise as a strategy to significantly augment humoral immune responses to HIV vaccines. Studies in mice and non-human primates have shown that extended dosing of immunogens can trigger long-lived germinal center responses, promote somatic hypermutation, and increase neutralizing antibody breadth. As one form of extended dosing, escalating-dosing (ED) immunization, where a given dose of antigen/adjuvant is administered as 7 injections of increasing dose over 2 weeks (7-ED), has been found to be one of the most effective ways to achieve these effects. This approach provides multifaceted benefits, such as allowing for improved antigen capture on follicular dendritic cells (FDCs) and augmenting follicular helper T cell priming. Furthermore, it results in the generation of long-lived germinal centers (GCs) with a more diverse repertoire of B cell clones that enter these GCs. However, such a multi-dose regimen presents significant feasibility challenges in terms of clinical translation.
Here we explored the parameter space of “reduced ED” immunizations employing fewer injections, aiming to increase clinical feasibility while retaining much of the immunological benefits of ED dosing compared to traditional bolus immunization. We carried out systematic studies varying number of doses, dose ratio, and dose intervals, immunizing mice and analyzing the subsequent immune responses looking for patterns maximizing the size of the antigen-specific GC response. A two shot reduced ED regimen (2-ED) consisting of dose 1 (20% of vaccine dose) on day 0 and a second shot (80% of vaccine dose) with a 7-day interval elicited prolonged optimal responses that were an order of magnitude improved over bolus immunization and enabled antigen capture of the second shot on FDCs, though not reaching the immune response levels elicited by the 7-ED regimen. Computational modeling of the germinal center response indicated that the 7ED regimen is able to maximize capture of native antigen as a consequence of high antibody titers prior to the final shot. These results suggested that sustained antigen availability at the time of the second immunization in our 2-ED regimen would boost innate inflammation in lymph nodes & improve antigen capture in follicles. Consistent with these predictions, we found that sustained second prime dosing by anchoring the antigen onto alum via a phosphoserine linker significantly improved the magnitude of the antigen-specific GC responses.
These results pave the way to safer and more potent cancer immunotherapies and vaccines via engineered kinetic approaches to administering these compounds. |
| first_indexed | 2024-09-23T09:15:50Z |
| format | Thesis |
| id | mit-1721.1/154366 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T09:15:50Z |
| publishDate | 2024 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1543662024-05-02T03:55:48Z Engineering kinetics of immunotherapies and vaccines Bhagchandani, Sachin Haresh Johnson, Jeremiah A. Irvine, Darrell J. Langer, Robert S. Massachusetts Institute of Technology. Department of Chemical Engineering The dynamic progression of immune responses to infections & tumors points to the possibility of an optimal temporal window for immune modulation as a key parameter that could influence protective outcomes. Altering kinetics in an attempt to orchestrate an immune response in resonance with the biological rhythm of innate and adaptive immunity could have significant returns with respect to improved efficacy and decreased toxicity; all without necessitating the approval of new agents. In this thesis, we explored two distinct strategies to engineer immunotherapy and vaccine kinetics. We show how these kinetics can significantly impact cellular and humoral immune responses, and carried out detailed investigations into the underlying mechanisms that govern these temporal effects. Firstly, imidazoquinolines (IMDs), small molecule agonists of Toll like receptor (TLR)-7 and/or TLR-8, are of great interest as potential anti-cancer therapeutics due to their ability to activate innate immune cells. Nevertheless, safe and effective systemic administration of these compounds in the clinic is an unsolved challenge due to dose-limiting toxicities, poor bioavailability, and severe immune-related adverse events upon intravenous administration. While attempts to deliver them via nanoparticle technologies have improved the potency of IMDs, achieving these outcomes while minimizing acute systemic inflammation has proven difficult. Here, we developed a bottlebrush prodrug (BPD) IMD library as a tool to provide a detailed understanding of how the kinetics of drug release impacts safety and tumor immune stimulation. Cylindrical BPDs featuring antibody-like dimensions (~10 nm), coaxial PEG chains, and TLR-7/8 agonists linked through cleavable linkers along their backbone were synthesized using ringopening metathesis polymerization (ROMP). By tuning the cleavable linker molecular structure, IMD-BPD constructs were identified that allowed for potent stimulation of innate immune cells in tumors while avoiding systemic increases in inflammatory cytokines, reductions in white blood cell counts, or liver toxicity. These BPDs enabled significant reductions in tumor growth in syngeneic tumor models and improved responses to anti-PD-1 checkpoint blockade. Single-cell RNA-sequencing revealed that IMD-BPDs promote dendritic cell activation and reduce immunosuppressive macrophages in the tumor microenvironment, changes that free TLR7/8 agonists were unable to achieve. Secondly, “extended dosing” of vaccines – immunization regimens that prolong exposure to antigen/adjuvant– has shown promise as a strategy to significantly augment humoral immune responses to HIV vaccines. Studies in mice and non-human primates have shown that extended dosing of immunogens can trigger long-lived germinal center responses, promote somatic hypermutation, and increase neutralizing antibody breadth. As one form of extended dosing, escalating-dosing (ED) immunization, where a given dose of antigen/adjuvant is administered as 7 injections of increasing dose over 2 weeks (7-ED), has been found to be one of the most effective ways to achieve these effects. This approach provides multifaceted benefits, such as allowing for improved antigen capture on follicular dendritic cells (FDCs) and augmenting follicular helper T cell priming. Furthermore, it results in the generation of long-lived germinal centers (GCs) with a more diverse repertoire of B cell clones that enter these GCs. However, such a multi-dose regimen presents significant feasibility challenges in terms of clinical translation. Here we explored the parameter space of “reduced ED” immunizations employing fewer injections, aiming to increase clinical feasibility while retaining much of the immunological benefits of ED dosing compared to traditional bolus immunization. We carried out systematic studies varying number of doses, dose ratio, and dose intervals, immunizing mice and analyzing the subsequent immune responses looking for patterns maximizing the size of the antigen-specific GC response. A two shot reduced ED regimen (2-ED) consisting of dose 1 (20% of vaccine dose) on day 0 and a second shot (80% of vaccine dose) with a 7-day interval elicited prolonged optimal responses that were an order of magnitude improved over bolus immunization and enabled antigen capture of the second shot on FDCs, though not reaching the immune response levels elicited by the 7-ED regimen. Computational modeling of the germinal center response indicated that the 7ED regimen is able to maximize capture of native antigen as a consequence of high antibody titers prior to the final shot. These results suggested that sustained antigen availability at the time of the second immunization in our 2-ED regimen would boost innate inflammation in lymph nodes & improve antigen capture in follicles. Consistent with these predictions, we found that sustained second prime dosing by anchoring the antigen onto alum via a phosphoserine linker significantly improved the magnitude of the antigen-specific GC responses. These results pave the way to safer and more potent cancer immunotherapies and vaccines via engineered kinetic approaches to administering these compounds. Ph.D. 2024-05-01T14:31:08Z 2024-05-01T14:31:08Z 2023-09 2024-04-17T18:56:05.222Z Thesis https://hdl.handle.net/1721.1/154366 In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Bhagchandani, Sachin Haresh Engineering kinetics of immunotherapies and vaccines |
| title | Engineering kinetics of immunotherapies and vaccines |
| title_full | Engineering kinetics of immunotherapies and vaccines |
| title_fullStr | Engineering kinetics of immunotherapies and vaccines |
| title_full_unstemmed | Engineering kinetics of immunotherapies and vaccines |
| title_short | Engineering kinetics of immunotherapies and vaccines |
| title_sort | engineering kinetics of immunotherapies and vaccines |
| url | https://hdl.handle.net/1721.1/154366 |
| work_keys_str_mv | AT bhagchandanisachinharesh engineeringkineticsofimmunotherapiesandvaccines |