Immunoengineering with biomaterials for enhanced cancer immunotherapy

Cancer immunotherapy has recently shown dramatic clinical success inducing durable response in patients of a wide variety of malignancies. Further improvement of the clinical outcome with immune related cancer treatment requests more exquisite manipulation of a patient’s immune system with increased immunity against diseases while mitigating the toxicities. To meet this challenge, biomaterials applied to immunoengineering are being developed to achieve tissue- and/or cell-specific immunomodulation and thus could potentially enhance both the efficacy and safety of current cancer immunotherapies. Here, we review the recent advancement in the field of immunoengineering using biomaterials and their applications in promoting different modalities of cancer immunotherapies, with focus on cell-, antibody-, immunomodulator-, and gene-based immune related treatments and their combinations with conventional therapies. Challenges and opportunities are discussed in applying biomaterials engineering strategies in the development of future cancer immunotherapies.

Targeting cancer stem cells by T cell engineering

Nicolas Pierre Desbaillets

The identification of cancer stem cells (CSCs) has fundamentally changed the understanding of tumor biology. CSCs drive tumor initiation and long term tumor growth, can cause relapse and are essential for metastatic colonization. These features place cancer stem cells in the focus for cancer therapy. Recently, great advances have been made in the field of cancer adoptive immunotherapy using engineered T cells. Combining both fields of cancer research to generate immune therapies directly targeting CSCs for increased efficacy and long-term anti-tumor effects would generate great hope for cancer patients. Herein, proof of concept is made that chimeric antigen receptor (CARs) T cells killing breast CSCs are capable of eliminating established metastases. Killing of the CSCs modifies the immune environment resulting in the loss of regulatory T cells and in the induction of an endogenous immune response directed against the tumor that is indispensable for treatment success. Antibody mediated ablation of the CAR T cells induced a rapid re-appearance of CSCs and re-establishment of an immunosuppressive environment in the tumor creating a need for continuous targeting of the CSCs. I demonstrate that endogenous T cell responses are less effective against CSCs than the rest of the tumor. Furthermore, proof is made across multiple tumor models, that activated immune cells and inflammation induce dedifferentiation of bulk tumor cells which regain stem-like phenotypes. This observation further emphasizes the importance of directly targeting the CSCs. Studying the interplay between CSCs and the immune system requires syngeneic, immune competent murine models. This greatly limits the transgenic markers that one can use to visualize, track and target CSCs. Herein, we developed different tolerant mouse models to study breast cancer stem cells in vivo. 4T1 breast adenocarcinoma cells were engineered to express hCEA or GFP-based model surface antigens under the control a stem cell specific promoter. These cells, injected into syngeneic model antigen-tolerant mice established lung metastases which were eliminated by CAR T cell therapy. To further validate this approach using endogenous CSC markers, a genetic cancer model (MMTV-PyMT) has been developed, where stem cell Identification is based on CD90 allelic differentiation. Overall, this work highlights an important interplay between CSCs and the immune system. My results suggest that a feedback loop may be created were immune attack induces CSCs, which are immune privileged and escape killing from endogenous T cells. Subsequently, CSCs induce and control an immunosuppressive environment leading to immune escape. This provides a strong rationale to develop CSC-targeted therapies to be administered in combination with immunotherapies.

EPFL2017

Targeting and Modulating Tumor-Associated Sites with Novel Nanoparticle-Based Immunotherapies

Laura Jeanbart

Cancer is a global disease and a leading cause of death worldwide. While surgery, radiotherapy and chemotherapy comprise the classical tools to eradicate tumors, they do not cure cancer, cannot prevent metastases, lead to side effects, and most importantly they do not instruct the patientʼs immune system to recognize and fight tumor cells. Since the discovery of the immune systemʼs implication in cancer, immunotherapies, which aim at using and educating the immune system to fight and reject cancer, have come to complement classical tumor-debulking methods. A major goal of immunotherapy is to induce or activate effector cytotoxic CD8+ T lymphocytes that can infiltrate and kill the tumor while overcoming immune suppressive mechanisms, which impede their efficacy. Moreover, cancer immunotherapies aim at inducing memory to tumor antigens to prevent relapse or metastases, which traditional therapies cannot do. Dendritic cell (DC) targeting and activation are key for inducing adaptive immunity. Our laboratory has developed synthetic nanoparticles (NPs) capable of draining through lymphatics to target skin-draining lymph nodes (LNs) and being phagocytosed by resident antigen-presenting cells (APCs) upon intradermal injection. We developed a reproducible method to conjugate tumor antigens to NPs and co-delivered them with CpG-conjugated NPs. We found that a NP vaccine composed of a single melanoma-derived peptide (TRP- 2180-188) led to dramatic tumor growth delay in melanoma and was more efficient than a NP vaccine containing several tumor antigens from whole tumor cell lysate (TL). These findings contradicted our hypothesis that immunization with TL might lead to a broader T cell response and hence improved therapeutic outcomes. Additionally, we found that the dose of CpG could modulate the magnitude of the therapeutic outcomes in both single epitope and multiple antigen based NP-vaccines. Considering the efficacy of the developed NP vaccines, we used them as a tool to ask a fundamental and extremely relevant question regarding the influence of vaccine administration site on clinical efficacy: is it therapeutically more beneficial to target a tumor- draining lymph node (tdLN), which is immune suppressed but tumor antigen-primed, or a non-tdLN, which is neither suppressed nor primed by the tumor? We found that targeting the tdLN with NP vaccines led to significantly enhanced therapeutic outcomes in two different tumor models over targeting a non-tdLN, and that efficacy relied on NP conjugation of antigen and adjuvant. This suggested that antigen drainage from the tumor might be available to APCs in the tdLN and we further hypothesized that therapies that lead to immunogenic tumor cell death might synergize with a tdLN-targeted adjuvant approach. While cytotoxic modalities, such as chemotherapy and radiotherapy, have traditionally been used for their ability to kill tumor cells, tumor cells shed antigens and debris upon cell death that drain to the tdLN. Consistent with our hypothesis, targeting an adjuvant to the tdLN enhanced therapeutic benefits of chemo- and radio- therapy, while targeting a non-tdLN did not. We hypothesized that targeting the tdLN with NP vaccines might switch the tdLN microenvironment from a suppressive to an immunogenic one. This suggested that direct targeting of active suppressive mechanisms in the tumor might further improve immunotherapy. We thus engineered a nano-sized micellar carrier loaded with 6-thioguanine (MC-6TG), a cytotoxic drug used in leukemia, and explored its use in targeting T cell- impairing myeloid-derived suppressor cells (MDSCs) in order to enhance the efficacy of therapeutic vaccines. MC-6TG entirely eradicated both Ly6c+ monocytic and Ly6g+ granulocytic MDSCs for up to 7 d in the blood, tumor and tdLN of tumor-bearing mice. Since MC-6TG also targeted certain subsets of macrophages and DCs, depleting MDSCs did not have an impact on the efficacy of a NP vaccine, which relies on APCs for efficacy. However, MC-6TG synergized with adoptively transferred CD8+ T cells, significantly delaying tumor growth and enhancing survival in a murine model of implantable melanoma. Overall, this thesis describes the design and implementation of a novel approach to immunotherapy: we engineered NP-based therapeutic vaccines, optimized their delivery route to enhance efficacy, and simultaneously tackled immune suppressive cells in the tumor microenvironment to allow optimal therapeutic outcomes. The technologies and methods developed in this work are particularly relevant to clinical oncology and have the potential to benefit cancer patients by improving cancer therapy efficacy.

EPFL2013

The era of bioengineering: how will this affect the next generation of cancer immunotherapy?

Cristiana Berti, Michele Graciotti, Harm-Anton Klok

Background: Immunotherapy consists of activating the patient's immune system to fight cancer and has the great potential of preventing future relapses thanks to immunological memory. A great variety of strategies have emerged to harness the immune system against tumors, from the administration of immunomodulatory agents that activate immune cells, to therapeutic vaccines or infusion of previously activated cancer-specific T cells. However, despite great recent progress many difficulties still remain, which prevent the widespread use of immunotherapy. Some of these limitations include: systemic toxicity, weak immune cellular responses or persistence over time and most ultimately costly and time-consuming procedures. Main body: Synthetic and natural biomaterials hold great potential to address these hurdles providing biocompatible systems capable of targeted local delivery, co-delivery, and controlled and/or sustained release. In this review we discuss some of the bioengineered solutions and approaches developed so far and how biomaterials can be further implemented to help and shape the future of cancer immunotherapy. Conclusion: The bioengineering strategies here presented constitute a powerful toolkit to develop safe and successful novel cancer immunotherapies.