CD3 Monoclonal Antibody Research Articles

B-343 Development of CD40 and HER2 Bispecific Antibodies for Enhanced Efficacy against HER2-Positive Tumors

Abstract Background CD40, a member of the tumor necrosis factor superfamily, is primarily expressed on antigen-presenting cells. This receptor plays a crucial role in facilitating the interaction between dendritic cells, activating antigen-specific T cells. Agonist antibodies targeting the CD40 receptor have the potential to mimic the natural CD40 ligand, fostering dendritic cell maturation and stimulating immunity against “cold” tumors. Although this approach has shown promise in preclinical studies, translating it to clinical success has been challenging. Only modest anti-tumor activity was observed in cancer patients, and none of the developed CD40 monoclonal antibodies (mAbs) progressed beyond early clinical trials, highlighting a need for improved anti-tumor efficacy. Methods In this study, we successfully developed an anti-human CD40 agonist rabbit monoclonal antibody using Yurogen's proprietary SMAB(TM) platform. The most potent CD40 mAb clone was combined with trastuzumab (an anti-HER2 mAb) to create a therapeutic bispecific antibody. Our goal is to leverage immune cell activation through HER2-targeted cancer therapy to achieve enhanced anti-tumor activity. Dozens of diverse CD40xHER2 bispecific antibody designs (both symmetry and asymmetry) were explored, with careful evaluation of expression yield, purity, and binding profiles for each target respectively. Results A few bispecific antibody designs demonstrated robust binding to both HER2 and CD40 antigen proteins, as well as receptor-expressing cell lines. Notably, two developed bispecific antibodies exhibited potent killing of HER2-positive cancer cells with the assistance of innate immune cells. Conclusions In sum, this study provides novel insights into designing bispecific antibodies against HER2 and CD40, offering a promising avenue for advancing cancer immunotherapy.

Segmental vitiligo distribution follows the underlying arterial blood supply territory: a hypothesis based on anatomo-clinical, pathological and physio-pathological studies.

Segmental vitiligo (SV) is a subset of vitiligo typically characterized by its unilateral distribution. The pathogenesis of SV remains unclear, and until now the two main patterns proposed for SV have lacked biological support. This calls for a new approach. Use data obtained from anatomo-clinical, pathological, and physio-pathological studies to formulate a new hypothesis on segmental vitiligo distribution and its pathogenesis. Using transparent templates of local arterial blood supply, we evaluated anatomical correspondence (AC) in 140 SV lesions according to the number of SV lesions that fit within the corresponding arterial blood-supply areas. SV lesions were graded as 1 (moderate: AC < 50%), 2 (good: AC > 50%), or 3 (excellent: AC of all lesions). To support this anatomical investigation, we searched for complementary assessments according to the activity of SV lesions. Arterial and periarterial network impairment and inflammatory infiltration were histologically studied using nerve growth factor (NGF) and CD4 and CD8 monoclonal antibodies. Increased blood flow of the underlying arteries was also investigated using thermography and ultrasonography. We recruited 140 patients with a sex ratio of 0.8 and mean age 26.13 years. Localizations: head and neck 84.28%; trunk 6.42%; upper limb 5%; genital areas 2.14%; lower limb 1.42%. The AC of each SV lesion with the underlying artery blood supply territory was rated as 72% excellent; 16% good; and 12% moderate. Histologically (40 patients), we found some periarterial network impairments. Thermal asymmetry was significantly associated with active SV (p < 0.001). We hypothesized that SV distribution corresponds to the underlying artery blood-supply territory.

Immunosuppressive leucosesterterpane and penta-nor-leucosesterterpane sesterterpenoids from Leucosceptrum canum

Five undescribed leucosesterterpane sesterterpenoids, leucosceptrines A−E, two undescribed penta-nor-leucosesterterpane (C20) sesterterpenoids, nor-leucosceptrines A and B, and three known analogues, were obtained from the aerial parts of Leucosceptrum canum of Chinese origin. Leucosceptrines A−C are the first examples of leucosesterterpane-type sesterterpenoids with unclosed dihydropyran rings and reverse configurations at chiral centers C-4 and/or C-12. Nor-leucosceptrines A and B possesses an unusual penta-nor-leucosesterterpane skeleton. Their structures were unambiguously elucidated through comprehensive spectroscopic analyses and single-crystal X-ray diffraction. A plausible biogenetic pathway for these sesterterpenoids was proposed. The immunosuppressive effects of these isolates on the secretion of the cytokine IFN-γ by T cells stimulated with anti-CD3/CD28 monoclonal antibodies were observed with different potencies.

Preparation and application of fluorescent monoclonal antibodies recognizing goat CD4+CD25+ regulatory T cells

Regulatory T cells (Tregs) are a subset of T cells participating in a variety of diseases including mycoplasmal pneumonia, contagious ecthyma, and so on. The role of Tregs in goat contagious ecthyma is not completely understood due to the lack of species-specific antibodies. Here, we developed a combination of CD4 and CD25 fluorescence monoclonal antibodies (mAb) to recognize goat Tregs and assessed its utility in flow cytometry, immunofluorescence staining. Using immunofluorescence staining, we found that the frequency of Treg cells was positively correlated with the viral load during orf virus infection. These antibodies could serve as important tools to monitor Tregs during orf virus infection in goats.Key points• A combination of fluorescent mAbs (C11 and D12) was prepared for the detection of goat Tregs.• C11 and D12 are effective in flow cytometry, immunofluorescence staining, and C11 has excellent species specificity.• The frequency of Treg cells was positively correlated with the viral load during orf virus infection.

Abstract CT192: A first-in-human phase 1 study of TQB2916, a novel CD40 agonist antibody for advanced malignancies

Abstract Background: CD40 receptor is a member of the tumor necrosis factor receptor family that plays a prominent role in immune responses. TQB2916, a humanized IgG2 CD40 monoclonal antibody, has demonstrated CD40 agonistic activity and promising anti-tumor activity in preclinical studies. A first-in-human study of TQB2916 single agent in advanced solid tumors and lymphomas is ongoing (NCT05213767). Methods: Patients with an ECOG performance status of 0 or 1, adequate hematologic and organ function and refractory to standard therapies met inclusion criteria. TQB2916 was given intravenously every 3 weeks until progression or unacceptable toxicity. Bayesian optimal interval (BOIN) design was used to determine the maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D). The objective is to assess the safety, tolerability, pharmacokinetics, and preliminary anti-tumor activity of TQB2916. Results: From April 2022 to November 2023, 18 patients with solid tumors and 2 with lymphoma have been treated with TQB2916 monotherapy, and were assigned to 7 cohorts (0.5 mg n=1, 2.5 mg n=1, 12.5 mg n=3, 60 mg n=3, 200 mg n=7, 300 mg n=2, and 400 mg n=3). Three dose limiting toxicities (DLTs) were observed: one with grade 3 pneumonia and one with grade 4 lipase/amylase increase in the 400 mg cohort; one with grade 3 pancreatitis in the 300 mg cohort. All patients experienced at least one treatment-related adverse event (TRAE). The most common TRAEs were lipase increase (n=15, 75%), amylase increase (n=14, 70%), lymphocyte count decrease (n=13, 65%), alanine aminotransferase (ALT) increase (n=12, 60%), alkaline phosphatase (ALP) increase (n=12, 60%), aspartate aminotransferase (AST) increase (n=11, 55%), hypoalbuminemia (n=11, 55%), and anorexia (n=11, 55%). Serious TRAEs occurred in 5 (25%) patients. Most of TRAEs were of grade 1 or grade 2 and manageable. Sixteen patients were evaluated for efficacy, and 3 of them achieved stable disease as per immune response evaluation criteria in solid tumors (iRECIST) and lymphoma response to immunomodulatory therapy criteria (LYRIC). The pharmacokinetics were well-behaved with increasing exposure dose-proportionally and no accumulation occurred after repeated dosing. The Cmax, AUC(0-t) and T1/2 of 400 mg single dosing were 109±21.8 μg/ml, 611±228 d*µg/mL and 5.54±3.37 d. Dose-dependent occupancy of CD40 was detected of 0.5 mg and above doses. Reduction in peripheral B cells and increasing in cytokines secretion were also observed. Conclusions: Pharmacodynamics analysis suggested that TQB2916 treatment achieved CD40 occupancy and immune activation with the changes in cytokines. Considering the safety profile and efficacy, 200 mg was determined as the preliminary expansion dose as it was well tolerated. Studies of TQB2916 in combination with immune checkpoint inhibitors and/or other anti-cancer therapies are ongoing. Citation Format: Yi Ba, Huilai Zhang, Ting Deng, Tao Ning, Qian Fan. A first-in-human phase 1 study of TQB2916, a novel CD40 agonist antibody for advanced malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT192.

Nanofluidic delivery implant sustains localization and maximizes efficacy of intratumoral immunotherapy

Intratumoral immunotherapy holds promise for improving cancer treatment efficacy. However, rapid clearance from the tumor upon bolus volume injections limits efficacy and impedes assessment of dose-dependent effects on the tumor immune microenvironment (TIME). To this end, we developed a drug-agnostic nanofluidic implant to deliver immunotherapy within the tumor, providing a mechanism for sustained and controlled intratumoral dosing. Diffusive drug elution from the implant reservoir is controlled by a nanofluidic membrane, which abrogates rapid drug elimination from the tumor and maximizes immunotherapy localization. Here we first achieve in vitro sustained release of agonist CD40 monoclonal antibody (mAb), anti-programmed death ligand-1 (PDL1) mAb, and immune-cell targeted polymeric prodrugs of Resiquimod (toll-like receptor 7/8,TLR 7/8) and a small molecule STING agonist. We then demonstrated in vivo sustained intratumoral drug localization of agonist CD40 Ab and anti-PDL1 Ab in the 4T1 murine model of triple-negative breast cancer (TNBC). Further, we show highly effective anti-tumor efficacy with radiation therapy and sustained intratumoral co-delivery of agonist CD40 Ab and anti-PDL1 Ab in the EMT6 TNBC murine model. Finally, we demonstrate the versatility of this implant by showing that sustained intratumoral delivery of the STING or Resiquimod polymeric prodrugs strongly inhibits 4T1 tumor growth. Collectively, these results support our nanofluidic system as a therapeutic platform technology to investigate sustained intratumoral dosing of immunotherapy.

Machine Learning Links T-cell Function and Spatial Localization to Neoadjuvant Immunotherapy and Clinical Outcome in Pancreatic Cancer.

Tumor molecular data sets are becoming increasingly complex, making it nearly impossible for humans alone to effectively analyze them. Here, we demonstrate the power of using machine learning (ML) to analyze a single-cell, spatial, and highly multiplexed proteomic data set from human pancreatic cancer and reveal underlying biological mechanisms that may contribute to clinical outcomes. We designed a multiplex immunohistochemistry antibody panel to compare T-cell functionality and spatial localization in resected tumors from treatment-naïve patients with localized pancreatic ductal adenocarcinoma (PDAC) with resected tumors from a second cohort of patients treated with neoadjuvant agonistic CD40 (anti-CD40) monoclonal antibody therapy. In total, nearly 2.5 million cells from 306 tissue regions collected from 29 patients across both cohorts were assayed, and over 1,000 tumor microenvironment (TME) features were quantified. We then trained ML models to accurately predict anti-CD40 treatment status and disease-free survival (DFS) following anti-CD40 therapy based on TME features. Through downstream interpretation of the ML models' predictions, we found anti-CD40 therapy reduced canonical aspects of T-cell exhaustion within the TME, as compared with treatment-naïve TMEs. Using automated clustering approaches, we found improved DFS following anti-CD40 therapy correlated with an increased presence of CD44+CD4+ Th1 cells located specifically within cellular neighborhoods characterized by increased T-cell proliferation, antigen experience, and cytotoxicity in immune aggregates. Overall, our results demonstrate the utility of ML in molecular cancer immunology applications, highlight the impact of anti-CD40 therapy on T cells within the TME, and identify potential candidate biomarkers of DFS for anti-CD40-treated patients with PDAC.

Peripheral MC1R Activation Modulates Immune Responses and is Neuroprotective in a Mouse Model of Parkinson’s Disease

BackgroundMelanocortin 1 receptor (MC1R) is a key pigmentation gene, and loss-of-function of MC1R variants that produce red hair may be associated with Parkinson’s disease (PD). We previously reported compromised dopaminergic neuron survival in Mc1r mutant mice and dopaminergic neuroprotective effects of local injection of a MC1R agonist to the brain or a systemically administered MC1R agonist with appreciable central nervous system (CNS) permeability. Beyond melanocytes and dopaminergic neurons, MC1R is expressed in other peripheral tissues and cell types, including immune cells. The present study investigates the impact of NDP-MSH, a synthetic melanocortin receptor (MCR) agonist that does not cross BBB, on the immune system and the nigrostriatal dopaminergic system in mouse model of PD.MethodsC57BL/6 mice were treated systemically with MPTP.HCl (20 mg/kg) and LPS (1 mg/kg) from day 1 to day 4 and NDP-MSH (400 µg/kg) or vehicle from day 1 to day 12 following which the mice were sacrificed. Peripheral and CNS immune cells were phenotyped and inflammatory markers were measured. The nigrostriatal dopaminergic system was assessed behaviorally, chemically, immunologically, and pathologically. To understand the role of regulatory T cells (Tregs) in this model, CD25 monoclonal antibody was used to deplete CD25 + Tregs.ResultsSystemic NDP-MSH administration significantly attenuated striatal dopamine depletion and nigral dopaminergic neuron loss induced by MPTP + LPS. It improved the behavioral outcomes in the pole test. Mc1r mutant mice injected with NDP-MSH in the MPTP and LPS paradigm showed no changes in striatal dopamine levels suggesting that the NDP-MSH acts through the MC1R pathway. Although no NDP-MSH was detected in the brain, peripheral, NDP-MSH attenuated neuroinflammation as observed by diminished microglial activation in the nigral region, along with reduced TNF-α and IL1β levels in the ventral midbrain. Depletion of Tregs was associated with diminished neuroprotective effects of NDP-MSH.ConclusionsOur study demonstrates that peripherally acting NDP-MSH confers protection on dopaminergic nigrostriatal neurons and reduces hyperactivated microglia. NDP-MSH modulates peripheral immune responses, and Tregs may be involved in the neuroprotective effect of NDP-MSH.

Clinical analysis of sirolimus as an alternative GVHD prophylaxis for patients with kidney injury undergoing allo-HSCT

Objective: To explore the feasibility of sirolimus as an alternative graft versus host disease (GVHD) prophylaxis in patients with kidney injury after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: Retrospective case series study. Medical records of 11 patients in Peking University People's Hospital from 1 August 2008 to 31 October 2022, who received sirolimus instead of cyclosporine to prevent GVHD, due to renal insufficiency after allo-HSCT, were analyzed retrospectively. Incidence of GVHD, infection, and transplant-associated thrombotic microangiopathy (TA-TMA), as well as renal function, were evaluated. Results: Among the 11 patients who received sirolimus, 6 were treated with haploidentical donor HSCT, and 5 were treated using matched sibling donor HSCT. The median (range) time of sirolimus administration was 30 (7-167) days after allo-HSCT, and the median (range) sirolimus course duration was 52 (9-120) days. During sirolimus treatment, 1 case did not undergo combined treatment with other prophylactic drugs, 3 cases received combined mycophenolate mofetil (MMF), and 1 case underwent combined CD25 monoclonal antibody treatment, while 6 cases had combined therapy with both MMF and CD25 monoclonal antibody. Of the 11 patients, 2 developed Grade Ⅲ acute GVHD, 1 developed severe pneumonia and died, and 1 developed TA-TMA, while nine patients had normal or improved renal function. Median (range) follow-up time was 130 (54-819) days. Non-relapse mortality was observed in 1 patient. Relapse mortality was also observed in 1 patient. Conclusion: Sirolimus-based alternative GVHD prophylaxis is a potentially viable option for patients undergoing allo-HSCT who cannot tolerate cyclosporine, but its efficacy and safety require further optimization and verification in prospective studies.

Humanized anti-CD25 monoclonal antibody as a salvage therapy for steroid-refractory acute graft-versus-host disease after hematopoietic stem cell transplantation

Objective: To investigate the efficacy of humanized anti-CD25 monoclonal antibody for steroid-refractory acute graft-versus-host disease (SR-aGVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Methods: A total of 64 patients with SR-aGVHD between June 2019 and October 2020 in Suchow Hopes Hematology Hospital were enrolled in this study. Humanized anti-CD25 monoclonal antibodies 1 mg·kg(-1)·d(-1) were administered on days 1, 3, and 8, and then once per week according to the disease progression. Efficacy was assessed at days 7, 14, and 28 after humanized anti-CD 25 treatment. Results: Of the 64 patients with a median age of 31 (15-63) years, 38 (59.4%) were male and 26 (40.6%) were female. The overall response (OR) rate of the humanized CD25 monoclonal antibody in 64 patients with SR-aGVHD on days 7, 14, and 28 were 48.4% (31/64), 53.1% (34/64), and 79.7% (51/64), respectively. Liver involvement is an independent risk factor for poor efficacy of humanized CD25 monoclonal antibody for SR-aGVHD at day 28 (OR=9.588, 95% CI 0.004-0.291, P=0.002). The median follow-up time for all patients was 17.1 (0.2-50.8) months from the start of humanized CD25 monoclonal antibody therapy. The 1- and 2-year OS rates were 63.2% (95% CI 57.1% -69.3%) and 52.6% (95% CI 46.1% -59.1%), respectively. The 1- and 2-year DFS rates were 58.4% (95% CI 52.1% -64.7%) and 49.8% (95% CI 43.4% -56.2%), respectively. The 1- and 2-year NRM rates were 28.8% (95% CI 23.1% -34.5%) and 32.9% (95% CI 26.8% -39.0%), respectively. The results of the multifactorial analysis showed that liver involvement (OR=0.308, 95% CI 0.108-0.876, P=0.027) and GVHD grade Ⅲ/Ⅳ (OR=9.438, 95% CI 1.211-73.577, P=0.032) were independent risk factors for OS. Conclusion: Humanized CD25 monoclonal antibody has good efficacy and safety for SR-aGVHD. This study shows that SR-aGVHD with pretreatment grade Ⅲ/Ⅳ GVHD and GVHD involving the liver has poor efficacy and prognosis and requires early intervention.

Construction of CD19 targeted dual- and enhanced dual-antibodies and their efficiency in the treatment of B cell malignancy

BackgroundT cell-redirecting bispecific antibodies establish a connection between endogenous T cells and tumor cells, activating T cells function to eliminate tumor cells without ex vivo genetic alteration or manipulation. Here, we developed a novel dual-specific antibody (DuAb) and an enhanced DuAb (EDuAb) with different stimulation signal to activate T cells, and evaluated their impact on the treatment of acute lymphoblastic leukemia (ALL).MethodsThe expression plasmids of the DuAb and EDuAb containing CD80 molecule were constructed by cloning heavy chain and light chain variable fragments from anti-human CD19 (HI19a) and CD3 (HIT3a) monoclonal antibody hybridomas, respectively. The activation and the anti-tumor efficacy of human T cells mediated by DuAb and EDuAb were evaluated in vitro. B-cell ALL xenograft NSG mouse model was established to investigate the therapeutic effect in vivo.ResultsEDuAb promoted the optimal expansion of primary human T cells with low expression of inhibitory markers in vitro than DuAb did. Both DuAb and EDuAb showed a similar capability in inducing healthy donor T cells to specifically eliminate B-ALL cell lines and primary blasts from patients. The similar ability was also observed in the patient-derived T cells. In vivo study showed that both DuAb and EDuAb significantly alleviated tumor burden and extended survival of B-ALL xenograft NSG mice. The median survival of PBS, DuAb and EDuAb treatment groups were 27, 38 and 45 days, respectively. The phenotype of T cells and cytokine release in peripheral blood (PB) of B-ALL xenograft NSG mice on day 24 were analyzed as well. The results showed that the proportion of CD8+ T cells and cytokine levels, including IL-2, IFN-γ and TNF-α, were higher in the EDuAb group than that of DuAb. Moreover, both DuAb and EDuAb significantly decreased the residual leukemia cells in PB of B-ALL xenograft NSG mice.ConclusionsBoth DuAb and EDuAb showed great potential as novel treatments for B-ALL in clinical applications. However, compared to DuAb, EDuAb showed a significant advantage in promoting the proliferation and survival of T cells. Furthermore, EDuAb showed a better promising effect on eliminating tumor cells and extending survival in vivo, which provides new insights for the development of new multi-specific antibodies.

Cell targeting and immunostimulatory properties of a novel Fcγ-receptor-independent agonistic anti-CD40 antibody in rhesus macaques

Targeting CD40 by agonistic antibodies used as vaccine adjuvants or for cancer immunotherapy is a strategy to stimulate immune responses. The majority of studied agonistic anti-human CD40 antibodies require crosslinking of their Fc region to inhibitory FcγRIIb to induce immune stimulation although this has been associated with toxicity in previous studies. Here we introduce an agonistic anti-human CD40 monoclonal IgG1 antibody (MAB273) unique in its specificity to the CD40L binding site of CD40 but devoid of Fcγ-receptor binding. We demonstrate rapid binding of MAB273 to B cells and dendritic cells resulting in activation in vitro on human cells and in vivo in rhesus macaques. Dissemination of fluorescently labeled MAB273 after subcutaneous administration was found predominantly at the site of injection and specific draining lymph nodes. Phenotypic cell differentiation and upregulation of genes associated with immune activation were found in the targeted tissues. Antigen-specific T cell responses were enhanced by MAB273 when given in a prime-boost regimen and for boosting low preexisting responses. MAB273 may therefore be a promising immunostimulatory adjuvant that warrants future testing for therapeutic and prophylactic vaccination strategies.

Emerging Anti-Diabetic Drugs for Beta-Cell Protection in Type 1 Diabetes.

Type 1 diabetes (T1D) is a chronic autoimmune disorder that damages beta cells in the pancreatic islets of Langerhans and results in hyperglycemia due to the loss of insulin. Exogenous insulin therapy can save lives but does not halt disease progression. Thus, an effective therapy may require beta-cell restoration and suppression of the autoimmune response. However, currently, there are no treatment options available that can halt T1D. Within the National Clinical Trial (NCT) database, a vast majority of over 3000 trials to treat T1D are devoted to insulin therapy. This review focuses on non-insulin pharmacological therapies. Many investigational new drugs fall under the category of immunomodulators, such as the recently FDA-approved CD-3 monoclonal antibody teplizumab. Four intriguing candidate drugs fall outside the category of immunomodulators, which are the focus of this review. Specifically, we discuss several non-immunomodulators that may have more direct action on beta cells, such as verapamil (a voltage-dependent calcium channel blocker), gamma aminobutyric acid (GABA, a major neurotransmitter with effects on beta cells), tauroursodeoxycholic acid (TUDCA, an endoplasmic reticulum chaperone), and volagidemab (a glucagon receptor antagonist). These emerging anti-diabetic drugs are expected to provide promising results in both beta-cell restoration and in suppressing cytokine-derived inflammation.

Glutamine Metabolism Underlies the Functional Similarity of T Cells between Nile Tilapia and Tetrapod.

As the lowest organisms possessing T cells, fish are instrumental for understanding T cell evolution and immune defense in early vertebrates. This study established in Nile tilapia models suggests that T cells play a critical role in resisting Edwardsiella piscicida infection via cytotoxicity and are essential for IgM+ B cell response. CD3 and CD28 monoclonal antibody crosslinking reveals that full activation of tilapia T cells requires the first and secondary signals, while Ca2+ -NFAT, MAPK/ERK, NF-κB, and mTORC1 pathways and IgM+ B cells collectively regulate T cell activation. Thus, despite the large evolutionary distance, tilapia and mammals such as mice and humans exhibit similar T cell functions. Furthermore, it is speculated that transcriptional networks and metabolic reprogramming, especially c-Myc-mediated glutamine metabolism triggered by mTORC1 and MAPK/ERK pathways, underlie the functional similarity of T cells between tilapia and mammals. Notably, tilapia, frogs, chickens, and mice utilize the same mechanisms to facilitate glutaminolysis-regulated T cell responses, and restoration of the glutaminolysis pathway using tilapia components rescues the immunodeficiency of human Jurkat T cells. Thus, this study provides a comprehensive picture of T cell immunity in tilapia, sheds novel perspectives for understanding T cell evolution, and offers potential avenues for intervening in human immunodeficiency.

Role of T Cells in Vaccine-Mediated Immunity against Marek's Disease.

Marek's disease virus (MDV), a highly cell-associated oncogenic α-herpesvirus, is the etiological agent of T cell lymphomas and neuropathic disease in chickens known as Marek's disease (MD). Clinical signs of MD include neurological disorders, immunosuppression, and lymphoproliferative lymphomas in viscera, peripheral nerves, and skin. Although vaccination has greatly reduced the economic losses from MD, the molecular mechanism of vaccine-induced protection is largely unknown. To shed light on the possible role of T cells in immunity induced by vaccination, we vaccinated birds after the depletion of circulating T cells through the IP/IV injection of anti-chicken CD4 and CD8 monoclonal antibodies, and challenged them post-vaccination after the recovery of T cell populations post-treatment. There were no clinical signs or tumor development in vaccinated/challenged birds with depleted CD4+ or CD8+ T cells. The vaccinated birds with a combined depletion of CD4+ and CD8+ T cells, however, were severely emaciated, with atrophied spleens and bursas. These birds were also tumor-free at termination, with no virus particles detected in the collected tissues. Our data indicated that CD4+ and CD8+ T lymphocytes did not play a critical role in vaccine-mediated protection against MDV-induced tumor development.

Sustained Intratumoral Administration of Agonist CD40 Antibody Overcomes Immunosuppressive Tumor Microenvironment in Pancreatic Cancer.

Agonist CD40 monoclonal antibodies (mAb) is a promising immunotherapeutic agent for cold-to-hot tumor immune microenvironment (TIME) conversion. Pancreatic ductal adenocarcinoma (PDAC) is an aggressive and lethal cancer known as an immune desert, and therefore urgently needs more effective treatment. Conventional systemic treatment fails to effectively penetrate the characteristic dense tumor stroma. Here, it is shown that sustained low-dose intratumoral delivery of CD40 mAb via the nanofluidic drug-eluting seed (NDES) can modulate the TIME to reduce tumor burden in murine models. NDES achieves tumor reduction at a fourfold lower dosage than systemic treatment while avoiding treatment-related adverse events. Further, abscopal responses are shown where intratumoral treatment yields growth inhibition in distant untreated tumors. Overall, the NDES is presented as a viable approach to penetrate the PDAC immune barrier in a minimally invasive and effective manner, for the overarching goal of transforming treatment.

Construction of Dual- and Enhanced Dual-Antibodies Targeting CD19 in the Treatment of B-ALL and Investigation of the Relevant Mechanisms

Objective: Acute lymphoblastic leukemia (ALL) is a hematological malignancy characterized by the development of immature lymphocytes. Although many patients can achieve complete remission (CR) after chemotherapy, only minority can sustain long term remission without relapse. In the past decade, chimeric antigen receptor (CAR) T cells have achieved unprecedented clinical responses for B cells malignancies, however, it still encounters with substantial challenges, such as expensive cost and treatment failure. T cell-redirecting bispecific antibodies is able to build the connection between endogenous T cells and tumor cells in order to activate T cells function to eliminate cancer cells without the need for ex vivo genetic alteration or manipulation of the T cells. It can provide an off-the-shelf immune-oncology therapy, unlike the long-term preparation before CAR-T infusion. Here, we developed the novel dual-specific antibody (DuAb) and enhanced DuAb (EDuAb) with different stimulation signals to activate T cells and explored their impact on the treatment of hematologic tumors by altering the function of T cells. Methods: The expression plasmids of dual-specific antibody targeting CD19 and CD3 (DuAb) and the enhanced DuAb (EDuAb) containing CD80 molecule were constructed by cloning heavy chain and light chain variable fragments from previously established anti-human CD19 (HI19a) and CD3 (HIT3a) monoclonal antibodies, respectively. Both DuAb and EDuAb were produced through a eukaryotic expression system. The activation of human primary T cells was evaluated after stimulated by DuAb and EDuAb in vitro, by detecting T cells proliferation, cytokine secretion, apoptosis and inhibitor marker expression. The antitumor efficacy of human primary T cells mediated by DuAb and EDuAb was evaluated through co-culture killing assay. B-ALL xenograft NSG mouse model was established to investigate the in vivo therapeutic effect. Results: EDuAb promoted the optimal expansion of primary human T cells with low expression of inhibitor marker in vitro than DuAb did (fold change of proliferation on day 9: 61.39 vs 19.23, p<0.0001; proportion of annexin V+: 11.83% vs 45.13%, p<0.0001, Tim3+: 20.08% vs 35.37%, p=0.007, PD-1+: 11.6% vs 34.3%, p=0.001, Lag3+: 29.12% vs 51.42%, p=0.006). In addition, BCL-XL was upregulated and IL2 secretion increased in EDuAb group. DuAb and EDuAb showed a similar capability in inducing healthy donor T cells to specifically eliminate B-ALL cell lines in vitro. At the concentration of 0.01nM, E/T ratio (2/1), the lysis of Nalm6 cells exceeded 96% after co-cultured for 48 hours. The similar ability was also observed in the patient-derived T cells. Both DuAb and EDuAb markedly suppressed tumor burden to baseline level and extended survival of B-ALL xenograft NSG mice. The median survival of vehicle, DuAb and EDuAb treatment group were 27, 38 and 45 days, respectively, which illustrated that EDuAb had a better therapeutic effect in vivo than that of DuAb (p=0.0066). The phenotype of T cells and cytokine release in peripheral blood of B-ALL xenograft NSG mouse model on day 24 were analyzed as well. The results showed that the proportion of CD8+ T cells and the cytokine levels, including IL2, IFN-γ and TNF-α, were higher in the EDuAb group than that of DuAb (CD8+: 0.746% vs 0.064%, p=0.0079; IL2: 1.862pg/ml vs 0.654pg/ml，p=0.0014; IFN-γ: 432.27pg/ml vs 1.48pg/ml, p= 0.047; TNF-α: 4.57pg/ml vs 2.08pg/ml, p=0.018). Both DuAb and EDuAb could significantly decrease the residual Nalm6 cells in PB of B-ALL xenograft NSG mice, and the residual tumor cells on day 24 were 1.61%, 0.45% and 0.29% in Vehicle, DuAb and EDuAb groups, respectively (Vehicle vs DuAb, p=0.0134; Vehicle vs EDuAb, p=0.0034; DuAb vs EDuAb, p=0.0169). Conclusion: Both DuAb and EDuAb showed great potential for clinical application as a novel treatment method for B-ALL. Compared with DuAb, there is a significant advantage for EDuAb to promote the proliferation and survival of T cells. In addition, EDuAb showed better promising effect to eliminate tumor cells and extend survival in vivo, which provides a new insight for constructing new multi-specific antibodies.

Delineation of T cell subsets in chronic rhinosinusitis with nasal polyps.

Detailed characterisation of CD45RA+ and CD45RO+ T cell subsets in both CD4+ and CD8+ cells in blood and tissue of patients with chronic rhinosinusitis with nasal polyps (CRSwNP) is lacking. We aimed to investigate T cell differentiation levels in blood and tissue and correlate this with CT score and white blood cell count. This case-control study was conducted on 21 patients with CRSwNP and 20 healthy controls. Lund-Mackay score was used for radiologic staging of chronic rhinosinusitis. T cell subsets were characterised in blood and nasal polyp tissue using CD4, CD8, CCR7, CD45RA, CD45RO, CD27, and CD95 monoclonal antibodies. Most variations in T cell subsets were detected in tissue rather than blood. A higher level of CD8+ TCM, CD4+ TSCMs and lower level of CD8+ TEM were detected in the blood of CRSwNP patients vs controls. In CRSwNP patients, substantial decrease of tissue CD8+ TNs, CD8+ TCMs, CD4+ TNs, and CD4+TSCMs with marked increase in the percentages of TEMs and TEMRAs were detected among CD4+ and CD8+ T cells compared with levels in blood. The reduction of TNs, TSCMs, and TCMs and accumulation of TEMs and TEMRAs subsets that function as effector cells in sinonasal mucosa, especially CD8+ T cells, might indicate the role of immunomodulation of memory/effector T-cells in the pathogenesis of CRSwNP.

CD40 monoclonal antibody and OK432 synergistically promote the activation of dendritic cells in immunotherapy

BackgroundColorectal cancer (CRC) with pulmonary metastasis usually indicates a poor prognosis, whereas patients may benefit from adoptive cell therapy. Tumor-specific cytotoxic T lymphocytes (CTLs) have been reported as a promising treatment for CRC. However, the antitumor effect of CTLs remains limited partially due to insufficient production of effector cells via the activation by antigen-presenting dendritic cells (DCs).MethodThis study showed that a combination of CD40 mAb and Picibanil (OK-432) could significantly enhance the activation of CTLs by DCs, both in vitro and in vivo. Flow cytometry, colon cancer mouse model, and pathological staining were employed to demonstrate the specific functions.ResultsThis approach promoted the maturation of DCs, augmented the production of stimulatory cytokines, and suppressed the secretion of inhibitory cytokines. Additionally, it facilitated the killing efficiency of CTLs via stimulating their proliferation while restraining the number of Tregs, concomitantly with the positive regulation of corresponding cytokines. Furthermore, the combined unit could hurdle the expansion of tumor cells on metastatic lungs in the colon cancer mouse model.ConclusionCollectively, the combination of CD40-mAb and OK-432 facilitated the maturation of DCs and enhanced the cytotoxicity of T cells, promising therapeutic approach against CRC.Graphical

Abstract 5372: CD3 and CD8 targeting of ionizable lipid nanoparticles for in vivo mRNA delivery to T cells

Abstract Introduction: Adoptive cell transfer (ACT) of T cells has emerged in recent years as a powerful immunotherapy against cancer. Currently, T cells are harvested from the patient or donor and are genetically modified ex vivo to enhance their cancer-fighting capabilities. However, this process is costly and more complex than administering off-the-shelf therapies such as small molecule drugs or monoclonal antibodies. The development of methods to transfect T cells in vivo remains an important endeavor for immunotherapies. Ionizable lipid nanoparticles (LNPs) have recently played a key role as carrier vehicles for mRNA in the Pfizer-BioNTech and Moderna mRNA vaccines. While ionizable LNPs delivering mRNA have now been FDA-approved for non-targeted immune cell delivery, their potential for targeting specific immune cell subtypes has yet to be fully realized. Delivering therapeutic genes that could reprogram T cells in vivo to recognize disease-relevant antigens would be of great clinical significance in reducing the lead time and cost of current ACT therapies. Methods: Ionizable LNPs were synthesized to encapsulate mCherry or Firefly Luciferase (FLuc) reporter gene mRNA with a fluorescent Cy7-labeled lipid on the LNP surface. CD3 monoclonal antibody, F(ab’)2 CD3e fragment, or CD8 diabody was conjugated to the LNP surface. In vitro, the aCD3- or aCD8-LNPs were incubated with Jurkat or TK-1 cell lines, respectively. LNP uptake was imaged using fluorescent confocal microscopy, and mCherry expression was quantified via flow cytometry. For in vivo delivery, the ionizable LNPs were injected i.v., and reporter gene expression and cell activation were analyzed via flow cytometry and bioluminescence imaging. Results: Confocal microscopy of ionizable LNP uptake in vitro highlighted differences in the internalization of the aCD3- and aCD8-LNPs in their respective cell lines, and transfection was observed with each targeting ligand. In murine models, aCD3-LNPs led to FLuc expression in the spleen and liver with increased accumulation in lymph nodes. aCD3-LNPs also transfected mCherry mRNA and activated splenic and circulating T cells. Cytokine concentrations were elevated in blood 5 and 24 h after aCD3-LNP injection. The impact of LNP lipid composition on transfection will be detailed in the presentation. Conclusions: We successfully packaged mRNAs of mCherry and FLuc reporter genes within ionizable LNPs and targeted them to T cells via the CD3 or CD8 receptor. The ionizable LNPs were capable of transfecting T cells in vitro and in vivo while causing transient activation, depletion, migration, cytokine release, and phenotypic shifts. Working towards the goal of receptor-mediated T cell targeting in vivo, we elucidate the circulation time, transfection efficiency, and activating potential of ionizable LNPs targeted to T cells in the spleen and blood via two potential targets, the CD3 and CD8 receptors. Citation Format: Elise R. Robinson, Aris J. Kare, Azadeh Kheirolomoom, Mohammed Inayathullah, Spencer K. Tumbale, Bo Wu, Marina N. Raie, Jai W. Seo, Felix B. Salazar, Ramasamy Paulmurugan, Anna M. Wu, Katherine W. Ferrara. CD3 and CD8 targeting of ionizable lipid nanoparticles for in vivo mRNA delivery to T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5372.