BACKGROUND: Delta-like ligand 3 (DLL3) is highly expressed on the cell surface of small cell lung cancer (SCLC), one of the most lethal malignancies, but minimally or not in normal tissues, making it an attractive target for SCLC. However, none of the DLL3-targeting antibody-drug conjugates (ADCs) have been approved for SCLC therapy yet. We developed DB-1314, the new anti-DLL3 ADC composed of a novel humanized anti-DLL3 monoclonal antibody (DB131401) conjugated with eight molecules of P1021 (topoisomerase I inhibitor), and described its preclinical profiles.
METHODS: The binding epitope for DB131401 and Rovalpituzumab was tested by biolayer interferometry. The binding affinity and specificity of DB-1314 to DLL3 and other homologous proteins were respectively measured by surface plasmon resonance and enzyme-linked immunosorbent assay. Internalization, bystander effects, and antibody-dependent cell-mediated cytotoxicity (ADCC) were assessed by respective assay. DLL3 was quantified by antibodies bound per cell assay and immunohistochemistry. In vitro and in vivo growth inhibition studies were evaluated in SCLC cell lines, and cell line/patient-derived xenograft models. The safety profile was measured in cynomolgus monkeys.
RESULTS: DB-1314 induces potent, durable, and dose-dependent antitumor effects in cells in vitro and in cell/patient-derived xenograft models in vivo. The killing activity of DB-1314 mechanically arises from P1021-induced DNA damage, whereby P1021 is delivered and released within tumor cells through DLL3-specific binding and efficient internalization. Bystander effects and ADCC also contribute to the antitumor activity of DB-1314. DB-1314 displays favorable pharmacokinetic and toxicokinetic profiles in rats and cynomolgus monkeys; besides, DB-1314 is well-tolerated at a dose of up to 60 mg/kg in monkeys.
CONCLUSIONS: These results suggest that DB-1314 may be a candidate ADC targeting DLL3 for the treatment of DLL3-positive SCLC, supporting further evaluation in the clinical setting.

Antisense oligonucleotides (ASOs) are promising therapeutics for treating various neurological disorders. However, ASOs are unable to readily cross the mammalian blood-brain barrier (BBB) and therefore need to be delivered intrathecally to the central nervous system (CNS). Here, we engineered a human transferrin receptor 1 (TfR1) binding molecule, the oligonucleotide transport vehicle (OTV), to transport a tool ASO across the BBB in human TfR knockin (TfRmu/hu KI) mice and nonhuman primates. Intravenous injection and systemic delivery of OTV to TfRmu/hu KI mice resulted in sustained knockdown of the ASO target RNA, Malat1, across multiple mouse CNS regions and cell types, including endothelial cells, neurons, astrocytes, microglia, and oligodendrocytes. In addition, systemic delivery of OTV enabled Malat1 RNA knockdown in mouse quadriceps and cardiac muscles, which are difficult to target with oligonucleotides alone. Systemically delivered OTV enabled a more uniform ASO biodistribution profile in the CNS of TfRmu/hu KI mice and greater knockdown of Malat1 RNA compared with a bivalent, high-affinity TfR antibody. In cynomolgus macaques, an OTV directed against MALAT1 displayed robust ASO delivery to the primate CNS and enabled more uniform biodistribution and RNA target knockdown compared with intrathecal dosing of the same unconjugated ASO. Our data support systemically delivered OTV as a potential platform for delivering therapeutic ASOs across the BBB.

Anti-CTLA-4 antibodies faced challenges due to frequent adverse events and limited efficacy, which spurred the exploration of next-generation CTLA-4 therapeutics to balance regulatory T cells (Tregs) depletion and CD8 T cells activation. CCR8, identified primarily on tumor-infiltrating Tregs, has become a target of interest due to the anti-tumor effects demonstrated by CCR8 antibody-mediated Tregs depletion. Single-cell RNA sequencing analysis reveals that CCR8-positive Tregs constitute a small subset, with concurrent expression of CCR8 and CTLA-4. Consequently, we proposed a novel bispecific antibody targeting CCR8 and CTLA-4 that had the potential to enhance T cell activation while selectively depleting intratumor Tregs. The candidate molecule 2MW4691 was developed in a tetravalent symmetric format, maintaining a strong binding affinity for CCR8 while exhibiting relatively weaker CTLA-4 binding. This selective binding ability allowed 2MW4691 to target and deplete tumor-infiltrating Tregs with higher specificity. In vitro assays verified the antibody\'s capacity for antibody-dependent cellular cytotoxicity (ADCC) to Tregs with high level of CTLA-4 expression, but not CD8 T cells with relatively low level of CTLA-4 on cell surface. Also, 2MW4691 inhibited the CTLA-4 pathway and enhanced T cell activation. The in vivo therapeutic efficacy of 2MW4691 was further demonstrated using hCCR8 or hCTLA-4 humanized mouse models and hCCR8/hCTLA-4 double knock-in mouse models. In cynomolgus monkeys, 2MW4691 was well-tolerated, exhibited the anticipated pharmacokinetic profile, and had a minimal impact on the peripheral T cell population. The promising preclinical results supported the further evaluation of 2MW4691 as a next-generation Treg-based therapeutics in clinical trials.

BACKGROUND: Achieving effective drug delivery to the central nervous system (CNS) remains a challenge for treating neurological disorders. Intrathecal (IT) delivery, which involves direct injection into the cerebrospinal fluid (CSF), presents a promising strategy. Large animal studies are important to assess the safety and efficacy of most drugs and treatments and translate the data to humans. An understanding of the influence of IT injection parameters on solute distribution within the CNS is essential to optimize preclinical research, which would potentially help design human clinical studies.
METHODS: A three-dimensional (3D) in vitro model of a cynomolgus monkey, based on MRI data, was developed to evaluate the impact of lumbar injection parameters on intrathecal solute dispersion. The parameters evaluated were (a) injection location, (b) bolus volume, (c) flush volume, (d) bolus rate, and (e) flush rate. To simulate the CSF flow within the subarachnoid space (SAS), an idealized CSF flow waveform with both cardiac and respiratory-induced components was input into the model. A solution of fluorescein drug surrogate tracer was administered in the lumbar region of the 3D in vitro model filled with deionized water. After injection of the tracer, the CSF system wide-solute dispersion was imaged using high-resolution cameras every thirty seconds for a duration of three hours. To ensure repeatability each injection protocol was repeated three times. For each protocol, the average spatial-temporal distribution over three hours post-injection, the area under the curve (AUC), and the percent injected dose (%ID) to extra-axial CSF (eaCSF) at three hours were determined.
RESULTS: The changes to the lumbar injection parameters led to variations in solute distribution along the neuro-axis. Specifically, injection location showed the most impact, enhancing the delivery to the eaCSF up to + 10.5%ID (p = 0.0282) at three hours post-injection. Adding a post-injection flush of 1.5 ml at 1 ml/min increased the solute delivery to the eaCSF by + 6.5%ID (p = 0.0218), while the larger bolus volume resulted in a + 2.3%ID (p = 0.1910) increase. The bolus and flush rates analyzed had minimal, statistically non-significant effects.
CONCLUSIONS: These results predict the effects of lumbar injection parameters on solute distribution in the intrathecal space in NHPs. Specifically, the choice of injection location, flush, and bolus volume significantly improved solute delivery to eaCSF. The in vitro NHP CSF model and results offer a system to help predict and optimize IT delivery protocols for pre-clinical NHP studies.

The gut microbiota has been demonstrated to play a significant role in the pathogenesis of Parkinson\'s disease (PD). However, conflicting findings regarding specific microbial species have been reported, possibly due to confounding factors within human populations. Herein, our current study investigated the interaction between the gut microbiota and host in a non-human primate (NHP) PD model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) using a multi-omic approach and a self-controlled design. Our transcriptomic sequencing of peripheral blood leukocytes (PBL) identified key genes involved in pro-inflammatory cytokine dysregulation, mitochondrial function regulation, neuroprotection activation, and neurogenesis associated with PD, such as IL1B, ATP1A3, and SLC5A3. The metabolomic profiles in serum and feces consistently exhibited significant alterations, particularly those closely associated with inflammation, mitochondrial dysfunctions and neurodegeneration in PD, such as TUDCA, ethylmalonic acid, and L-homophenylalanine. Furthermore, fecal metagenome analysis revealed gut dysbiosis associated with PD, characterized by a significant decrease in alpha diversity and altered commensals, particularly species such as Streptococcus, Butyrivibrio, and Clostridium. Additionally, significant correlations were observed between PD-associated microbes and metabolites, such as sphingomyelin and phospholipids. Importantly, PDPC significantly reduced in both PD monkey feces and serum, exhibiting strong correlation with PD-associated genes and microbes, such as SLC5A3 and Butyrivibrio species. Moreover, such multi-omic differential biomarkers were linked to the clinical rating scales of PD monkeys. Our findings provided novel insights into understanding the potential role of key metabolites in the host-microbiota interaction involved in PD pathogenesis.

BACKGROUND: TG6050 was designed as an improved oncolytic vector, combining the intrinsic properties of vaccinia virus to selectively replicate in tumors with the tumor-restricted expression of recombinant immune effectors to modify the tumor immune phenotype. These properties might be of particular interest for \"cold\" tumors, either poorly infiltrated or infiltrated with anergic T cells.
METHODS:  TG6050, an oncolytic vaccinia virus encodes single-chain human interleukin-12 (hIL-12) and full-length anti-cytotoxic T-lymphocyte-associated antigen-4 (@CTLA-4) monoclonal antibody. The relevant properties of TG6050 (replication, cytopathy, transgenes expression and functionality) were extensively characterized in vitro. The biodistribution and pharmacokinetics of the viral vector, @CTLA-4 and IL-12, as well as antitumoral activities (alone or combined with immune checkpoint inhibitors) were investigated in several \"hot\" (highly infiltrated) and \"cold\" (poorly infiltrated) syngeneic murine tumor models. The mechanism of action was deciphered by monitoring both systemic and intratumoral immune responses, and by tumor transcriptome analysis. The safety of TG6050 after repeated intravenous administrations was evaluated in cynomolgus monkeys, with a focus on the level of circulating IL-12.
RESULTS: Multiplication and propagation of TG6050 in tumor cells in vitro and in vivo were associated with local expression of functional IL-12 and @CTLA-4. This dual mechanism translated into a strong antitumoral activity in both \"cold\" and \"hot\" tumor models (B16F10, LLC1 or EMT6, CT26, respectively) that was further amplified when combined with anti-programmed cell death protein-1. Analysis of changes in the tumor microenvironment (TME) after treatment with TG6050 showed increases in interferon-gamma, of CD8+T cells, and of M1/M2 macrophages ratio, as well as a drastic decrease of regulatory T cells. These local modifications were observed alongside bolstering a systemic and specific antitumor adaptive immune response. In toxicology studies, TG6050 did not display any observable adverse effects in cynomolgus monkeys.
CONCLUSIONS: TG6050 effectively delivers functional IL-12 and @CTLA-4 into the tumor, resulting in strong antitumor activity. The shift towards an inflamed TME correlated with a boost in systemic antitumor T cells. The solid preclinical data and favorable benefit/risk ratio paved the way for the clinical evaluation of TG6050 in metastatic non-small cell lung cancer (NCT05788926 trial in progress).

In preclinical protein therapeutic development studies, the emergence of anti-drug antibodies (ADA) can potentially impact drug pharmacokinetics and safety. While immunogenicity assessment is not mandatory in preclinical studies, banking samples can be valuable for interpreting unexpected pharmacological responses. Immunoassays that use generic reagents across different drug molecules can simplify ADA assessment and expedite sample evaluations. This work showcases the ability of the Gyrolab automated immunoassay platform to detect and quantify both drug-free and drug-bound (total) ADAs to monoclonal antibody (mAb) therapeutics in cynomolgus monkey preclinical studies. Compared to the previously reported total ADA ELISA, the Gyrolab assay exhibited a wider signal dynamic range and increased drug tolerance. Similar sensitivity, dynamic range and cut point factors were observed for four therapeutic mAbs of different isotypes using the Gyrolab assay. Here we present a comparison of ADA assays using bridging ELISA, total ADA ELISA and total ADA Gyrolab formats in a cynomolgus monkey study where the subjects were treated with a single dose of a mAb therapeutic. We demonstrate that the total ADA assays detected host ADA responses at earlier time points compared to the bridging ELISA. The Gyrolab assay has the best correlation between signal-to-noise (S/N) and titer over a wide ADA concentration range, highlighting the utility of Gyrolab in S/N reporting of ADA response to eliminate the need for secondary titer assays. Collectively, our results demonstrate that the generic ADA Gyrolab assay minimizes the necessity for extensive assay development and optimization for therapeutic mAbs, streamlining preclinical immunogenicity assessment to enable interpretation of pharmacological data.

Novel engineered IL-2 agonists strive to increase the therapeutic window of aldesleukin (human IL-2) by increasing selectivity toward effector over regulatory T cells and reducing dose-limiting toxicities. Here we describe ANV419, an IL-2/anti-IL2 antibody fusion protein designed for selective IL-2 receptor βγ (IL-2 Rβγ) activation by sterically hindering IL-2 from binding to IL-2 Rα. The fusion protein has an IL-2 connected to the light chain complementarity-determining region (CDR) domain of a humanized antibody that binds to IL-2 at the same epitope as IL-2 Rα. Optimization of the selectivity and pharmacological properties led to the selection of ANV419. ANV419 preferentially expands CD8+ T cells and natural killer (NK) cells over Tregs and can be safely administered at doses that elicit strong pharmacodynamic effects and efficacy in mouse tumor models. Its anti-tumor efficacy was enhanced when combined with programmed cell death protein 1 (PD-1) or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) checkpoint inhibitors. ANV419 also enhances the NK cell killing capacity and increases tumor growth inhibition when used alongside trastuzumab in a Her-2+ xenograft mouse model. In cynomolgus monkeys, the estimated half-life of ANV419 is 24 h, and doses that induced sustained expansion of effector cells were well tolerated without the severe toxicities typically observed with high-dose IL-2. These data support the clinical development of ANV419 in solid tumors and hematological malignancies as monotherapy and in combination with checkpoint inhibitors or agents that induce antibody-dependent cellular cytotoxicity. ANV419 is currently in Phase 1/2 clinical development and may provide cancer patients with a wider therapeutic window than aldesleukin.

An influenza vaccine approach that overcomes the problem of viral sequence diversity and provides long-lived heterosubtypic protection is urgently needed to protect against pandemic influenza viruses. Here, to determine if lung-resident effector memory T cells induced by cytomegalovirus (CMV)-vectored vaccines expressing conserved internal influenza antigens could protect against lethal influenza challenge, we immunize Mauritian cynomolgus macaques (MCM) with cynomolgus CMV (CyCMV) vaccines expressing H1N1 1918 influenza M1, NP, and PB1 antigens (CyCMV/Flu), and challenge with heterologous, aerosolized avian H5N1 influenza. All six unvaccinated MCM died by seven days post infection with acute respiratory distress, while 54.5% (6/11) CyCMV/Flu-vaccinated MCM survived. Survival correlates with the magnitude of lung-resident influenza-specific CD4 + T cells prior to challenge. These data demonstrate that CD4 + T cells targeting conserved internal influenza proteins can protect against highly pathogenic heterologous influenza challenge and support further exploration of effector memory T cell-based vaccines for universal influenza vaccine development.

We investigate the ocular dimensions and shape by using Lenstar900 (LS900), A-scan ultrasonography, and Magnetic Resonance Imaging (MRI) in highly myopic Macaca fascicularis. The ocular dimensions data of LS900, A-scan ultrasonography and MRI was assessed from 8 eyes (4 adult male cynomolgus macaque) with extremely high myopia (≤-1000DS) and compared by means of coefficients of concordance and 95% limits of agreement. Multiple regression analysis was performed to explore the associations between ocular biometry, volume, refraction and inter-instrument discrepancies. Test-retest reliability of three measurements of ocular parameters at two time points was almost equal (intraclass correlation = 0.831 to 1.000). The parallel-forms reliability of three measurements was strong for vitreous chamber depth (VCD) (coefficient of concordance = 0.919 to 0.981), moderate for axial length (AL) (coefficient of concordance = 0.486 to 0.981), and weak for anterior chamber depth (ACD) (coefficient of concordance = 0.267 to 0.621) and lens thickness (LT) (coefficient of concordance = 0.035 to 0.631). The LS900 and MRI systematically underestimated the ACD and LT comparing to A-scan ultrasonography (P < 0.05). Notably, the average AL on LS900 displayed a significant correlation with those on MRI (r = 0.978, P < 0.001) and A-scan ultrasonography (r = 0.990, P < 0.001). Almost 4/5 eyeballs were prolate. The mean eyeball volume positively correlated with AL (r = 0.782, P = 0.022), the width (r = 0.945, P = 0.000), and the length (r = 0.782, P = 0.022) of eyeball, while negatively correlated with SER (r = -0.901, P = 0.000). In conclusion, there was a high inter-instrument concordance for VCD with LS900, A-scan ultrasonography and MRI, while ACD and LT were underestimated with LS900 compared to A-scan ultrasonography, and the LS900 and A-scan ultrasonography could reliably measure the AL. MRI further revealed an equatorial globe shape in extremely myopic non-human primates.