Immune Checkpoint Blockade Antibodies Research Articles

Core-shell nanomedicine based on multifunctional tetrahedral DNA nanostructures for synergistic enhancement of tumor chemodynamic/chemo-immunotherapy

Immune checkpoint blockade therapy has made great strides in cancer treatment, but conventional immune checkpoint blockade antibodies often lead to overactivation of the immune system and severe immune-related adverse effects. Herein, we report the design of a nanomedicine (denoted as CPD@M−TDN) based on multifunctional tetrahedral DNA nanostructures (M−TDN). In this system, a bimetallic metal–organic framework (Cu/ZIF-8) is synthesized as the core; doxorubicin-loaded polydopamine acts as a shell to reduce the immunogenicity of the nanomaterials in peripheral blood. Finally, the CpG oligodeoxynucleotides and PD-L1 aptamer-based M−TDN are coupled to the core–shell structure nanomedicine through the biotin-avidin-system. Under the acidic tumor microenvironment, the decomposition of Cu/ZIF-8 and the release of copper ions and doxorubicin can lead to immunogenic death of tumor cells through chemodynamic/chemotherapy. Furthermore, the M−TDN has the dual effects of weakening the immunosuppressive microenvironment with PD-L1 aptamer and promoting dendritic cell activation with the immunostimulant CpG. Overall, the developed CPD@M−TDN can effectively enhance the response rate to immunotherapy and has excellent potential in the field of integrated tumor treatment.

Noncovalently particle-anchored cytokines with prolonged tumor retention safely elicit potent antitumor immunity.

Preclinical studies have shown that immunostimulatory cytokines elicit antitumor immune responses but their clinical use is limited by severe immune-related adverse events upon systemic administration. Here, we report a facile and versatile strategy for noncovalently anchoring potent Fc-fused cytokine molecules to the surface of size-discrete particles decorated with Fc-binding peptide for local administration. Following intratumoral injection, particle-anchored Fc cytokines exhibit size-dependent intratumoral retention. The 1-micrometer particle prolongs intratumoral retention of Fc cytokine for over a week and has minimal systemic exposure, thereby eliciting antitumor immunity while eliminating systemic toxicity caused by circulating cytokines. In addition, the combination of these particle-anchored cytokines with immune checkpoint blockade antibodies safely promotes tumor regression in various syngeneic tumor models and genetically engineered murine tumor models and elicits systemic antitumor immunity against tumor rechallenge. Our formulation strategy renders a safe and tumor-agnostic approach that uncouples cytokines' immunostimulatory properties from their systemic toxicities for potential clinical application.

Abstract 7174: Pharmacokinetics and immunogenicity of anti-PD-1 antibody in humanized FcRn mouse models compared to immunocompetent mouse models

Abstract Introduction: The development and use of therapeutic antibodies in cancer therapy has increased significantly in recent years, led by the success of approved immune checkpoint blockade antibodies targeting PD-1 and PD-L1 axis. However, obtaining more clinically relevant pharmacokinetics (PK), safety and efficacy data for antibodies is still challenging in preclinical phase. Humanized FcRn (hFcRn) transgenic mouse model has a more faithful catabolism compared to WT mice, providing more accurate and predictable PK data of innovative antibody-based therapeutics at discovery stage[1]. In this study, we sought to investigate pharmacokinetics and immunogenicity characteristics of anti-PD-1 antibody in hFcRn transgenic mice and provide guidance for its differentiation of prediction value for drug PK and safety by comparing to WT mice. Methods: Non-tumor bearing hFcRn mice and wild type C57BL/6 mice were divided into 2 groups, 5 mice were enrolled into each group. Mice were administered anti-PD-1(Nivolumab) at 10 mg/kg single dose after grouping by intravenous (IV) injection. Blood samples at 12 timepoints (15min, 6h, 1, 2, 4, 7, 10, 14, 21, 28, 35, 42 days) post-dosing were collected for PK and Anti-Drug Antibody (ADA) analysis by MSD and ELISA. Results: Nivolumab clearance in hFcRn mice followed a typical linear profile with rapid distribution phase and slow elimination phase (t1/2 = 350 to 400 h). While the PK profile in C57BL/6 mice displayed non-linear clearance and very short elimination phase (t1/2 = 45 to 50 h). This data demonstrated that hFcRn mice have better correlated half-life with human (Nivolumab single dose by IV with 10mg/kg, t1/2 = 595 h) [2]. ADA analysis revealed that it was produced starting from Day 10 in wild type C57BL/6 mice and the frequency of ADA induced by Nivolumab in wild type mice (2/5) was higher than hFcRn mice (0/5). The variation of Nivolumab level was correlated with ADA production in wild type mice. This suggested hFcRn shows lower immunogenicity than wild type mice for human IgG drug and can potentially improve negative effect of ADA interference on PK evaluation. Conclusion: The result of this study demonstrated that the PK data in hFcRn mouse model was more predictive of human PK profile compared to wild type C57BL/6 mice. This advances innovation in antibody-based therapeutics and translational applications, with improved PK, safety and efficacy evaluation for preclinical human IgG drug development in cancer therapy.

Perioperative immunotherapy for esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the main prevalent histological subtype and accounts for 85% of esophageal cancer cases worldwide. Traditional treatment for ESCC involves chemotherapy, radiotherapy, and surgery. However, the overall prognosis remains unfavorable. Recently, immune checkpoint blockade (ICB) therapy using anti-programmed cell death-1 (PD-1)/PD-1 ligand (PD-L1) antibodies have not only achieved remarkable benefits in the clinical management of ESCC but have also completely changed the treatment approach for this cancer. In just a few years, ICB therapy has rapidly advanced and been added to standard first-line treatment regimen in patients with ESCC. However, preoperative immunotherapy is yet to be approved. In this review, we summarize the ICB antibodies commonly used in clinical immunotherapy of ESCC, and discuss the advances of immunotherapy combined with chemotherapy and radiotherapy in the perioperative treatment of ESCC, aiming to provide reference for clinical management of ESCC patients across the whole course of treatment.

Metformin-Mediated Fast Charge-Reversal Nanohybrid for Deep Penetration Piezocatalysis-Augmented Chemodynamic Immunotherapy of Cancer.

Immune checkpoint blockade (ICB) therapy still suffers from insufficient immune response and adverse effect of ICB antibodies. Chemodynamic therapy (CDT) has been demonstrated to be an effective way to synergize with ICB therapy. However, a low generation rate of reactive oxygen species and poor tumor penetration of CDT platforms still decline the immune effects. Herein, a charge-reversal nanohybrid Met@BF containing both Fe3O4 and BaTiO3 nanoparticles in the core and Metformin (Met) on the surface was fabricated for tumor microenvironment (TME)- and ultrasound (US)-activated piezocatalysis-chemodynamic immunotherapy of cancer. Interestingly, Met@BF had a negative charge in blood circulation, which was rapidly changed into positive when exposed to acidic TME attributed to quaternization of tertiary amine in Met, facilitating deep tumor penetration. Subsequently, with US irradiation, Met@BF produced H2O2 based on piezocatalysis of BaTiO3, which greatly enhanced the Fenton reaction of Fe3O4, thus boosting robust antitumor immune response. Furthermore, PD-L1 expression was inhibited by the local released Met to further augment the antitumor immune effect, achieving effective inhibitions for both primary and metastatic tumors. Such a combination of piezocatalysis-enhanced chemodynamic therapy and Met-mediated deep tumor penetration and downregulation of PD-L1 provides a promising strategy to augment cancer immunotherapy.

Non-invasive transdermal delivery of biomacromolecules with fluorocarbon-modified chitosan for melanoma immunotherapy and viral vaccines

Transdermal drug delivery has been regarded as an alternative to oral delivery and subcutaneous injection. However, needleless transdermal delivery of biomacromolecules remains a challenge. Herein, a transdermal delivery platform based on biocompatible fluorocarbon modified chitosan (FCS) is developed to achieve highly efficient non-invasive delivery of biomacromolecules including antibodies and antigens. The formed nanocomplexes exhibits effective transdermal penetration ability via both intercellular and transappendageal routes. Non-invasive transdermal delivery of immune checkpoint blockade antibodies induces stronger immune responses for melanoma in female mice and reduces systemic toxicity compared to intravenous injection. Moreover, transdermal delivery of a SARS-CoV-2 vaccine in female mice results in comparable humoral immunity as well as improved cellular immunity and immune memory compared to that achieved with subcutaneous vaccine injection. Additionally, FCS-based protein delivery systems demonstrate transdermal ability for rabbit and porcine skins. Thus, FCS-based transdermal delivery systems may provide a compelling opportunity to overcome the skin barrier for efficient transdermal delivery of bio-therapeutics.

Antitumour effect of the mitochondrial complex III inhibitor Atovaquone in combination with anti-PD-L1 therapy in mouse cancer models

Immune checkpoint blockade (ICB) provides effective and durable responses for several tumour types by unleashing an immune response directed against cancer cells. However, a substantial number of patients treated with ICB develop relapse or do not respond, which has been partly attributed to the immune-suppressive effect of tumour hypoxia. We have previously demonstrated that the mitochondrial complex III inhibitor atovaquone alleviates tumour hypoxia both in human xenografts and in cancer patients by decreasing oxygen consumption and consequently increasing oxygen availability in the tumour. Here, we show that atovaquone alleviates hypoxia and synergises with the ICB antibody anti-PD-L1, significantly improving the rates of tumour eradication in the syngeneic CT26 model of colorectal cancer. The synergistic effect between atovaquone and anti-PD-L1 relied on CD8+ T cells, resulted in the establishment of a tumour-specific memory immune response, and was not associated with any toxicity. We also tested atovaquone in combination with anti-PD-L1 in the LLC (lung) and MC38 (colorectal) cancer syngeneic models but, despite causing a considerable reduction in tumour hypoxia, atovaquone did not add any therapeutic benefit to ICB in these models. These results suggest that atovaquone has the potential to improve the outcomes of patients treated with ICB, but predictive biomarkers are required to identify individuals likely to benefit from this intervention.

Gene-activating nanomedicine for the tumor-oriented infiltration of T cells to enhance immunotherapy against solid tumors

The insufficient infiltration of T cells in solid tumors hinders the therapeutic efficacy of immune checkpoint blockade (ICB) antibodies and chimeric antigen receptor (CAR)-T cells. Promoting T or CAR-T cells to efficiently and specifically migrate into solid tumors is critical for improving current immunotherapies, which remains a challenge. Herein, we proposed a CRISPR-based transcriptional activation (CRISPRa) nanomedicine for mobilizing tumor cells to recruit T cells by activating the expression of T cell chemokines CXC-chemokine ligand (CXCL) 9, CXCL10, and CXCL11. We demonstrated that the CRISPRa nanomedicine could dramatically upregulate the expression of these T cell chemokines in tumor cells, thereby facilitating T cell migration directionally into solid tumors. Intratumoral injection of the CRISPRa nanomedicine inhibited the growth of different solid tumors including melanoma, pancreatic, colonic, and breast cancers. Moreover, tumor-specific versions of the CRISPRa nanomedicine possessing the ability to upregulate the T cell chemokine expression only in tumors rather than normal tissues or cells were constructed. Systemic injection of the tumor-specific CRISPRa nanomedicine specifically recruited T or CAR-T cells into solid tumors and improved the therapeutic effects of ICB antibodies (anti-PD-L1 or anti-CTLA4) and CAR-T cells. Thus, the gene-activating nanomedicine provides a promising strategy for enhancing T cell infiltration to improve current immunotherapies against solid tumors.

Tumor acidity-activatable macromolecule autophagy inhibitor and immune checkpoint blockade for robust treatment of prostate cancer.

Immune checkpoint blockade (ICB) antibody such as anti-PD-L1 (aPD-L1) activates cytotoxic T cells (CTLs) to combat cancer, but they showed poor efficacy in prostate cancer (PCa). Lysosome-dependent autophagy is utilized by cancer cells to degrade their MHC-I and to lower their vulnerability to TNF-α and CTLs. Lysosomal pH-sensitive polymeric nanoparticle as a drug delivery carrier may also be a novel autophagy inhibitor to boost immunotherapy, but such an important effect has not been investigated. Herein, we developed a unique tumor acidity-activatable macromolecular nanodrug (called P-PDL1-CP) with the poly(2-diisopropylaminoethyl methacrylate) (PDPA) core and the conjugations of both aPD-L1 and long-chain polyethylene glycol (PEG) coating. The PDPA core was demonstrated to disturb lysosome to block the autophagic flux, thus elevating the cancer cell's MHC-I expression and vulnerability to the TNF-α and CTLs. Long-chain PEG facilitated a good tumor accumulation of P-PDL1-CP nanodrug. Furthermore, P-PDL1-CP nanodrug inhibited tumor autophagy, which synergized with aPD-L1 to promote the tumor-infiltrating CTLs and DCs maturation, to elevate intratumoral TNF-α and IFN-γ levels, and to elicit an anti-tumor immune memory effect in mice for PCa growth inhibition with low side effects. This study verified the synergistic anti-PCa treatment between autophagy inhibition and PD-L1 blockade and meantime broadened the application of pH-sensitive macromolecular nanodrug. STATEMENT OF SIGNIFICANCE: A macromolecular nanodrug, comprising the PDPA core and the surface conjugation of both aPD-L1 antibodies and long-chain PEG coating via a tumor acidity-labile α-carboxy-dimethylmaleic anhydride amine bond, was developed. Tumoral acidity triggered the release of aPD-L1 for immunotherapy. Meantime, the charge switch of the remanent nanodrug enhanced the cancer cell uptake of PDPA, which disturbed the lysosomes to inhibit autophagy. This advanced nanodrug promoted the tumor-infiltrating CTLs and DCs maturation, elevated the intratumoral TNF-α and IFN-γ levels, and elicited the robust anti-tumor immune memory effect. This study demonstrated that the pH-sensitive PDPA macromolecule could serve as a carrier for the aPD-L1 delivery and as an efficient autophagy inhibitor to boost the immunotherapy of prostate cancer.

BSBM-03 A NOVEL COMBINED IMMUNOTHERAPY TO IMPROVE THERAPEUTIC RESPONSES IN SYMPTOMATIC BRAIN METASTASIS BASED ON TARGETING A SUBPOPULATION OF IMMUNOSUPPRESSIVE ASTROCYTES

Abstract The diagnosis of brain metastasis involves high morbidity and mortality. Recently, immune checkpoint blockade antibodies (ICB) have shown clinical benefits mainly when applied to asymptomatic brain metastasis patients. However, variability is broad and responses to this therapy drop considerably when treating clinically relevant disease. Although potentially involved in the lack of response to immunotherapy, corticoids do not seem to fully explain this situation. Thus, it is currently unknown how to effectively target symptomatic brain metastases with immunotherapy. We previously reported a clinically relevant protumoral program driven by STAT3 activation in a subpopulation of reactive astrocytes during advanced stages of the disease. By further exploiting astrocyte heterogeneity, we have found a potential strategy to improve the number of responders to immunotherapy in symptomatic brain metastasis. Specifically, we have developed a comprehensive strategy including genetic and pharmacologic approaches to define a novel immunosuppressive axis involving astrocyte-secreted TIMP1 signaling on CD63+ CD8+ T cells. Based on these findings, we developed a combined immunotherapy to boost the systemic activation of T cells with ICB while blocking local TIMP1-dependent immunosuppression in various preclinical models. Furthermore, the detection of TIMP1 in the CSF provides a biomarker to select patients who would benefit the most from the combined immunotherapy. Even more, our data using Patient Derived Organotypic Cultures from fresh brain metastasis neurosurgeries confirmed that our therapeutic strategy is valid for symptomatic brain metastases from any primary source. In conclusion, our study has identified a novel combined immunotherapy that could be especially relevant for symptomatic brain metastases. Our findings have emerged from a strong scientific rationale whereby a specific subpopulation of astrocytes is shown to activate the local immunosuppressive environment for brain-infiltrating CD8+ T cells.

Single-dose injectable nanovaccine-in-hydrogel for robust immunotherapy of large tumors with abscopal effect.

Current cancer immunotherapy [e.g., immune checkpoint blockade (ICB)] only benefits small subsets of patients, largely due to immunosuppressive tumor microenvironment (TME). In situ tumor vaccination can reduce TME immunosuppression and thereby improve cancer immunotherapy. Here, we present single-dose injectable (nanovaccines + ICBs)-in-hydrogel (NvIH) for robust immunotherapy of large tumors with abscopal effect. NvIH is thermo-responsive hydrogel co-encapsulated with ICB antibodies and novel polymeric nanoparticles loaded with three immunostimulatory agonists for Toll-like receptors 7/8/9 (TLR7/8/9) and stimulator of interferon genes (STING). Upon in situ tumor vaccination, NvIH undergoes rapid sol-to-gel transformation, prolongs tumor retention, sustains the release of immunotherapeutics, and reduces acute systemic inflammation. In multiple poorly immunogenic tumor models, single-dose NvIH reduces multitier TME immunosuppression, elicits potent TME and systemic innate and adaptive antitumor immunity with memory, and regresses both local (vaccinated) and distant large tumors with abscopal effect, including distant orthotopic glioblastoma. Overall, NvIH holds great potential for tumor immunotherapy.

Immunotherapy for Recurrent Glioma-From Bench to Bedside.

Glioma is the most aggressive malignant tumor of the central nervous system, and most patients suffer from a recurrence. Unfortunately, recurrent glioma often becomes resistant to established chemotherapy and radiotherapy treatments. Immunotherapy, a rapidly developing anti-tumor therapy, has shown a potential value in treating recurrent glioma. Multiple immune strategies have been explored. The most-used ones are immune checkpoint blockade (ICB) antibodies, which are barely effective in monotherapy. However, when combined with other immunotherapy, especially with anti-angiogenesis antibodies, ICB has shown encouraging efficacy and enhanced anti-tumor immune response. Oncolytic viruses and CAR-T therapies have shown promising results in recurrent glioma through multiple mechanisms. Vaccination strategies and immune-cell-based immunotherapies are promising in some subgroups of patients, and multiple new tumor antigenic targets have been discovered. In this review, we discuss current applicable immunotherapies and related mechanisms for recurrent glioma, focusing on multiple preclinical models and clinical trials in the last 5 years. Through reviewing the current combination of immune strategies, we would like to provide substantive thoughts for further novel therapeutic regimes treating recurrent glioma.

Design of Mitoxantrone‐Loaded Biomimetic Nanocarrier with Sequential Photothermal/Photodynamic/Chemotherapy Effect for Synergized Immunotherapy

AbstractMetastatic triple‐negative breast cancer (TNBC) has a poor prognosis and high mortality with no effective treatment options, and immunotherapy is highly anticipated as a potential treatment but is limited by the lack of tumor‐infiltrating T lymphocytes in TNBC. Herein, red blood cell (RBC) membrane‐camouflaged polyphosphoester (PPE) nanoparticles (RBC@PPEMTO/PFA) are prepared as the nanocarriers of mitoxantrone (MTO) and perfluoroalkane (PFA) for synergized immunotherapy. The encapsulated MTO can generate heat and reactive oxygen species (ROS) to achieve photothermal and photodynamic therapy; moreover, ROS further triggers the self‐accelerating release of MTO from the ROS‐sensitive PPE core to enable chemotherapy. The RBC@PPEMTO/PFA‐mediated sequential photothermal/photodynamic/chemotherapy efficiently promotes the infiltration of CD8+ T cells into TNBC tumor tissue and synergizes the therapeutic activity of an immune checkpoint blockade antibody for metastatic TNBC treatment in distant and lung metastasis models. This biomimetic nanomedicine of MTO provides a convenient and available strategy to sensitize TNBC to immune checkpoint blockade antibody.

A non-drug chemotherapy-like synergizes with gas-/immunotherapy based on cancer cell membrane camouflage-functionalized nanoplatform

Traditional drug chemotherapy reveals numerous unsatisfactory aspects for malignant tumors that is prone to recurrence and metastasis, such as low therapy effect, systemic side effects, and multidrug resistance. Based on the above considerations, we herein propose a non-drug chemotherapy-like in synergy with gas-/immunotherapy strategy based on tumor cell membrane (M) coating Ferulic acid (FA)-L-Arg-ovalbumin (OVA) nanoparticles (F-L-O@M NPs). It is found that the non-drug of FA can efficiently induce cancer cell apoptosis via the Janus kinases/signal transducer and activator of transcription 3 (JAK/STAT3) signal pathway. Moreover, the generation of NO gas ascribed to the oxidation of L-Arg by H2O2, not only restricts the respiratory metabolism of mitochondria and reduces the generation of ATP, but also downregulates the expression of P-gp protein, exhibiting a superior synergistic with FA-mediated antineoplastic. More importantly, NO gas augments FA-induced tumor cell apoptosis and efficiently release tumor-associated antigens, which in synergy with OVA enables significant activation and recruits cytotoxic T lymphocytes to infiltrate in tumor tissues, further combining with immune checkpoint blockade antibody to trigger a long-term immune memory response, as well as anti-metastasis/recurrence. It is highly expected that such a non-drug chemotherapy-like strategy that combines with gas-/immunotherapy showing great promising in the clinical translational potential of nanomedicine.

Development of a novel modified vaccine (TheraVacM) for curative treatment of mouse solid tumors

Monotherapy with immune checkpoint blockade (ICB) antibodies (anti-CTLA4 and anti-PD1/PDL-1) is only effective for 20% to 30% of patients with certain cancers. Patients with cancers harboring few effector T cells (Teffs) are insensitive to ICB therapy. The lack of tumor-specific Teffs is predominantly caused by the paralysis of tumor-infiltrating dendritic cells (TiDCs) resulting from immunosuppression in the tumor microenvironment. We have identified a potent combination of high mobility group nucleosome binding domain 1 (HMGN1, N1) and fibroblast stimulating lipopeptide-1 (FSL-1) that can synergistically trigger maturation of both mouse and human DCs. Accordingly, we designed a combinational anti-cancer immunotherapy with two arms: an immune-activating arm consisting of N1 and FSL-1 to stimulate the generation of Teffs by triggering full maturation of TiDCs, and an ICB arm using anti-PDL-1 or anti-CTLA4 to prevent Teffs from being silenced in the tumor tissue. This combinational immunotherapeutic vaccination regimen dubbed modified TheraVac (TheraVacM) has proved particularly effective as it cured 100% of mice bearing established ectopic CT26 colon and RENCA kidney tumors. The resultant tumor-free mice were resistant to subsequent re-challenge with the same tumors, indicating the generation of long-term tumor specific protective immunity. Since the immune-activating arm also induces full maturation of human DCs, and anti-PDL-1 or anti-CTLA4 have been FDA-approved, this combinational immunotherapy has the potential to be an effective clinical therapy for patients with solid tumors.

Sustained release hydrogel for durable locoregional chemoimmunotherapy for BRAF-mutated melanoma

The wide prevalence of BRAF mutations in diagnosed melanomas drove the clinical advancement of BRAF inhibitors in combination with immune checkpoint blockade for treatment of advanced disease. However, deficits in therapeutic potencies and safety profiles motivate the development of more effective strategies that improve the combination therapy's therapeutic index. Herein, we demonstrate the benefits of a locoregional chemoimmunotherapy delivery system, a novel thermosensitive hydrogel comprised of gelatin and Pluronic® F127 components already widely used in humans in both commercial and clinical products, for the co-delivery of a small molecule BRAF inhibitor with immune checkpoint blockade antibody for the treatment of BRAF-mutated melanoma. In vivo evaluation of administration route and immune checkpoint target effects revealed intratumoral administration of antagonistic programmed cell death protein 1 antibody (aPD-1) lead to potent antitumor therapy in combination with BRAF inhibitor vemurafenib. The thermosensitive F127-g-Gelatin hydrogel that was evaluated in multiple murine models of BRAF-mutated melanoma that facilitated prolonged local drug release within the tumor (>1 week) substantially improved local immunomodulation, tumor control, rates of tumor response, and animal survival. Thermosensitive F127-g-Gelatin hydrogels thus improve upon the clinical benefits of vemurafenib and aPD-1 in a locoregional chemoimmunotherapy approach for the treatment of BRAF-mutated melanoma.

Abstract 3242: Efficacy evaluation by novel humanized mouse models for preclinical study of ADCs combined with immunotherapy

Abstract Antibody-drug conjugates (ADCs) are effective anti-tumor therapies with high specificity, with little toxicity and side effects. Xenograft tumor models based on immunodeficient mice have been used for evaluating the human anti-tumor efficacy of ADCs. However, the antibody-mediated immune response of ADCs is not well evaluated in immunodeficient mice. To this end, we have developed BALB/c-hPD1 humanized mouse model to evaluate the efficacy of ADCs in combination with immunotherapy. Trastuzumab deruxtecan (T-DXd, DS-8201a) is a HER2-targeting ADC. In vitro efficacy studies showed that T-DXd effectively bound to the HER2-positive cell line SK-BR-3, resulting in strong endocytosis and induction of apoptosis. It has also been shown to kill HER2-negative MDA-MB-468 cells through a bystander effect both in vitro and in vivo. In vivo efficacy studies have demonstrated that ADCs can effectively inhibit human tumor cell growth in immunodeficient mice. In addition to human tumor cell lines, the efficacy of ADCs was also studied in BALB/c-hPD1mice engrafted with murine colon cancer cells model, and the results showed that T-DXd and Keytruda could significantly inhibit CT26-hHER2 tumor growth, with the tumor growth inhibition rates being 57% and 66%, respectively, Tumor growth inhibition rate of the combined treatment group was about 91%, which was superior compared to the efficacy of single drug treatment. The evaluation of Fc segment-mediated effect (such as ADCC, CDC and ADCP) of ADCs antibodies was carried out in humanized immune system mouse models, such as NCG-hIL15 and NCG-hSGM3. In summary, we have established a drug evaluation platform using various humanized mouse models to study the synergistic anti-tumor effects of ADCs combined with immune checkpoint blockade antibodies. Citation Format: Fang Zhu, Hongyan Sun, Qian Lu, Yuan Fang, Jianming Xu, Cunxiang Ju, Hongyu Wang, Santi Suryani Chen, Zhiying Li, Mark Wade Moore, Jing Zhao, Xiang Gao. Efficacy evaluation by novel humanized mouse models for preclinical study of ADCs combined with immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3242.

Oral delivery of anti-PD-L1 antibody for cancer immunotherapy against orthotopic colorectal tumors

Despite the approval of immune checkpoint blockade (ICB) for colorectal cancer treatment, its objective response rate remains to be improved, especially for non-immunogenic tumors. Moreover, systemically administrated ICB antibodies is usually associated with immune-related adverse effects (irAEs). Herein, we report novel oral administration of anti-programmed cell death protein L1 (anti-PD-L1) complexes for immunotherapy against colorectal tumors. Antibodies could form nanocomplexes with fluorocarbon modified chitosan (FCS) to acquire greatly improved transmucosal penetration ability, owing to the ability of FCS to reduce mucus binding and temporary open tight junctions between epithelial cells. As evidenced in orthotopic colorectal tumors on mice, orally administrated FCS/anti-PD-L1 nanocomplexes exhibited greatly improved intestinal permeability and significant intertumoral penetration, and if combined with oxaliplatin (OXA) chemotherapy to induce an immunogenic tumor phenotype, could finally inhibit the growth of tumors and prolong the animal survival. Notably, compared to systematic injection of anti-PD-L1, oral administration of FCS/anti-PD-L1 achieved comparable therapeutic efficacy with five-fold dosage, and exhibited reduced tendency of systemic irAEs as exhibited by the decreased percentage of Th17 cells in lymph nodes. Our work here provides a simple but effective strategy for immunotherapy by oral administration of ICB antibodies, achieving strong antitumor immune responses without the concern of systemic irAEs.

Tumor-infiltrating regulatory Tcells as targets of cancer immunotherapy.

Regulatory Tcells (Tregs) are abundant in tumor tissues, raising a question of whether immunosuppressive tumor-infiltrating Tregs (TI-Tregs) can be selectively depleted or functionally attenuated to evoke effective anti-tumor immune responses by conventional Tcells (Tconvs), without perturbing Treg-dependent immune homeostasis in healthy organs and causing autoimmunity. Here, we review current cancer immunotherapy strategies, including immune checkpoint blockade (ICB) antibodies against CTLA-4 and PD-1 and discuss their effects on TI-Tregs. We also discuss approaches that exploit differentially regulated molecules on the cell surface (e.g., CTLA-4) and intracellularly (e.g., Tcell receptor signaling molecules) between TI-Tregs and Tconvs as well as their dependence on cytokines (e.g., IL-2) and metabolites (e.g., lactate). We envisage that targeting TI-Tregs could be effective as a monotherapy and/or when combined with ICB antibodies.

Oral Delivery of Therapeutic Antibodies with a Transmucosal Polymeric Carrier.

Therapeutic proteins are playing increasingly important roles in treating numerous types of diseases. However, oral administration of proteins, especially large ones (e.g., antibodies), remains a great challenge due to their difficulties in penetrating intestinal barriers. Herein, fluorocarbon-modified chitosan (FCS) is developed for efficient oral delivery of different therapeutic proteins, in particular large ones such as immune checkpoint blockade antibodies. In our design, therapeutic proteins are mixed with FCS to form nanoparticles, lyophilized with appropriate excipients, and then filled into enteric capsules for oral administration. It has been found that FCS could promote transmucosal delivery of its cargo protein via inducing transitory rearrangement of tight junction associated proteins between intestinal epithelial cells and subsequently release free proteins into blood circulation. It is shown that at a 5-fold dose oral delivery of anti-programmed cell death protein-1 (αPD1) or its combination with anti-cytotoxic T-lymphocyte antigen 4 (αCTLA4) using this method could achieve comparable antitumor therapeutic responses to that achieved by intravenous injection of corresponding free antibodies in various types of tumor models and, more excitingly, result in significantly reduced immune-related adverse events. Our work successfully demonstrates the enhanced oral delivery of antibody drugs to achieve systemic therapeutic responses and may revolutionize the future clinical usage of protein therapeutics.