anti-OX40 Antibody Research Articles

SHR-1806, a robust OX40 agonist to promote T cell-mediated antitumor immunity

ABSTRACT Anti-CTLA-4 and anti-PD-1/PD-L1 antibodies have significantly revolutionized cancer immunotherapy. However, the persistent challenge of low patient response rates necessitates novel approaches to overcome immune tolerance. Targeting immunostimulatory signaling may have a better chance of success for its ability to enhance effector T cell (Teff) function and expansion for antitumor immunity. Among various immunostimulatory pathways, the evidence underscores the potential of activating OX40-OX40L signaling to enhance CD8+ T cell generation and maintenance while suppressing regulatory T cells (Tregs) within the tumor microenvironment (TME). In this study, we introduce a potent agonistic anti-OX40 antibody, SHR-1806, designed to target OX40 receptors on activated T cells and amplify antitumor immune responses. SHR-1806 demonstrates a high affinity and specificity for human OX40 protein, eliciting FcγR-mediated agonistic effects, T cell activation, antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities in vitro. In human OX40 knock-in mice bearing MC38 tumor, SHR-1806 shows a trend toward a higher potency than the reference anti-OX40 antibody produced in-house, GPX4, an analog of pogalizumab, the most advanced drug candidate developed by Roche. Furthermore, SHR-1806 displays promising anti-tumor activity alone or in combination with toll-like receptor 7 (TLR7) agonist or PD-L1 inhibitor in mouse models. Evaluation of SHR-1806 in rhesus monkeys indicates a favorable safety profile and typical pharmacokinetic characteristics. Thus, SHR-1806 emerges as a robust OX40 agonist with promising therapeutic potential.

Durable improvements in atopic dermatitis in the head and neck and across other anatomic regions with rocatinlimab

In a randomized phase 2b trial (NCT03703102) for adult patients with moderate-to-severe atopic dermatitis (AD), treatment with the T cell rebalancing anti-OX40 receptor antibody rocatinlimab (AMG 451/KHK4083) led to significant improvements in clinical measurements versus placebo including whole-body Eczema Area and Severity Index (EASI) score. AD manifestations can impact variable anatomic regions, and involvement of the head and neck, a sensitive, hard-to-treat area, can negatively impact quality of life. In this post hoc analysis, we investigated response to rocatinlimab treatment across anatomic regions, including the head and neck. Least squares mean change from baseline to Week 56 in EASI score was analyzed by anatomic region (head and neck, trunk, upper extremities, or lower extremities) for patients with baseline moderate-to-severe AD in the respective anatomic region, using mixed models for repeated measures. Rocatinlimab groups were compared with placebo at Week 16. The proportion of patients achieving at least 75% reduction from baseline in EASI (EASI-75) was calculated. Probability of relapsing in EASI-75 during the off-treatment follow-up period (Weeks 36–56) was estimated using a Kaplan − Meier approach. At Week 16, decrease from baseline in mean EASI score was greater with all rocatinlimab regimens versus placebo across all anatomic regions for patients with baseline moderate-to-severe AD in the respective region (all P < 0.001). EASI scores continued to improve on treatment after Week 16 and were maintained during the off-treatment period across all regions. Among patients with baseline moderate-to-severe AD in the head and neck (n = 219; rocatinlimab, n = 174; placebo, n = 45), mean difference (rocatinlimab vs placebo) at Week 16 in LS mean percent change in head and neck EASI score ranged from − 30.4% to − 42.6% across treatment regimens. In patients who received rocatinlimab from the start of the trial, 47% − 71% achieved EASI-75 in the head and neck at Week 36. Among EASI-75 responders at Week 36, the probability of relapsing in EASI-75 in any region was low (< 25% in the head and neck) 20 weeks after treatment discontinuation until Week 56.Rocatinlimab treatment led to durable improvements in AD across multiple anatomic regions, including the sensitive head and neck region.Graphical abstract

Phase 2b randomized clinical trial of amlitelimab, an anti-OX40 ligand antibody, in patients with moderate-to-severe atopic dermatitis

Amlitelimab, a fully human nondepleting monoclonal antibody targeting OX40 ligand on antigen-presenting cells, could prevent T-cell-driven inflammation seen in atopic dermatitis (AD). This trial evaluated the efficacy and safety of amlitelimab in adults with AD. In this 2-part, phase 2b, randomized, double-blinded placebo-controlled trial (NCT05131477), patients received subcutaneous amlitelimab every 4 weeks at doses of 250 mg with 500-mg loading dose, 250 mg, 125 mg, or 62.5 mg, or placebo for 24 weeks in Part 1 (1:1:1:1:1 randomization). In Part 2, clinical responders were reallocated 3:1 to withdraw amlitelimab or continue the previous dose regimen for 28 weeks. The primary end point was percent change in Eczema Area and Severity Index (EASI) from baseline to Week 16. 390 and 190 patients enrolled in Part 1 and Part 2, respectively. Significant percent change decreases in EASI were observed with amlitelimab vs. placebo (P<.001). Clinical responses at Week 24 (Investigator Global Assessment 0/1 and/or EASI-75) were maintained at Week 52 in patients continuing or withdrawn from amlitelimab. In patients maintaining clinical response at Week 52 while off-treatment, >80% had serum amlitelimab concentrations below a 4-μg/mL threshold for several weeks prior to Week 52. Reductions in AD-related biomarkers during Part 1 were maintained through Part 2. Amlitelimab was well tolerated over 52 weeks. Amlitelimab treatment significantly reduced clinical and biomarker responses, and was well tolerated in adults with AD through Week 52. Sustained responses were observed in the majority of patients after amlitelimab withdrawal for 28 weeks.

Impact of isotype on the mechanism of action of agonist anti-OX40 antibodies in cancer: implications for therapeutic combinations

BackgroundOX40 has been widely studied as a target for immunotherapy with agonist antibodies taken forward into clinical trials for cancer where they are yet to show substantial efficacy. Here, we...

Nano-Pulse Stimulation Treatment Inhibits Pan02 Murine Pancreatic Tumor Growth and Induces a Long-Term Adaptive Immune Response with Abscopal Effects When Combined with Immune-Enhancing Agents.

Pancreatic cancer is associated with a poor prognosis and immunotherapy alone has not demonstrated sufficient efficacy in the treatment of nonresectable tumors. Nano-Pulse Stimulation™ therapy (NPS™) applies nanosecond electric pulses that lead to regulated cell death, exposing tumor antigen to the immune system. To establish a primary Pan02 tumor, mice were intradermally injected with Pan02 cells into the right flank. Secondary, rechallenge tumors and distal, secondary tumors (abscopal response) were established by injecting Pan02 cells into the opposite left flank. After 5 days of tumor growth, one of the tumors was treated with NPS, followed by injection with an immune-enhancing agent to stimulate an immune response. Growth of the treated primary tumor and untreated rechallenge tumors (injected 60-days post-treatment) or distal secondary tumors (injected simultaneously with the primary) was monitored. NPS in combination with the adjuvant and TLR agonist, resiquimod (RES), was the optimal treatment regimen for both eliminating a primary Pan02 tumor as well as inhibiting growth of a Pan02 cell rechallenge tumor. This inhibition of the rechallenge tumor injected 2 months after eliminating the primary tumor suggests a long-term immune response had been stimulated. Additional support for this came from the observations that depleting CD8+ T-cells reduced inhibition of rechallenge tumor growth by 35% and rechallenge tumors had 3-fold more CD8+ T-cells than tumors injected after surgical resection of the primary tumor. When the NPS-treated tumor was immediately injected with the anti-OX40 antibody to agonize the function of the costimulatory T cell receptor, OX40, up to 80% of untreated abscopal tumors were eliminated. NPS plus RES was the most effective at both eliminating a primary tumor and inhibiting a rechallenge tumor. NPS treatment followed by injection of aOX40 was the most effective at inhibiting the growth of an untreated abscopal tumor.

The Role of OX40-OX40L Axis in the Pathogenesis of Atopic Dermatitis.

OX40 is a co-stimulatory immune checkpoint molecule that promotes the activation and the effector function of T lymphocytes through interaction with its ligand (OX40L) on antigen-presenting cells. OX40-OX40L axis plays a crucial role in Th1 and Th2 cell expansion, particularly during the late phases or long-lasting response. Atopic dermatitis is characterized by an immune dysregulation of Th2 activity and by an overproduction of proinflammatory cytokines such as interleukin (IL)-4 and IL-13. Other molecules involved in its pathogenesis include thymic stromal lymphopoietin, IL-33, and IL-25, which contribute to the promotion of OX40L expression on dendritic cells. Lesional skin in atopic dermatitis exhibits a higher level of OX40L+-presenting cells compared with other dermatologic diseases or normal skin. Recent clinical trials using antagonizing anti-OX40 or anti-OX40L antibodies have shown symptom improvement and cutaneous manifestation alleviation in patients with atopic dermatitis. These findings suggest the relevance of the OX40-OX40L axis in atopic dermatitis pathogenesis.

Adapting Ferritin, a Naturally Occurring Protein Cage, to Modulate Intrinsic Agonism of OX40.

Ferritin is a multivalent, self-assembling protein scaffold found in most human cell types, in addition to being present in invertebrates, higher plants, fungi, and bacteria, that offers an attractive alternative to polymer-based drug delivery systems (DDS). In this study, the utility of the ferritin cage as a DDS was demonstrated within the context of T cell agonism for tumor killing. Members of the tumor necrosis factor receptor superfamily (TNFRSF) are attractive targets for the development of anticancer therapeutics. These receptors are endogenously activated by trimeric ligands that occur in transmembrane or soluble forms, and oligomerization and cell-surface anchoring have been shown to be essential aspects of the targeted agonism of this receptor class. Here, we demonstrated that the ferritin cage could be easily tailored for multivalent display of anti-OX40 antibody fragments on its surface and determined that these arrays are capable of pathway activation through cell-surface clustering. Together, these results confirm the utility, versatility, and developability of ferritin as a DDS.

Anti-OX40 Antibody Combined with HBc VLPs Delays Tumor Growth in a Mouse Colon Cancer Model

ObjectiveCombination immunotherapy strategies targeting OX40, a co-stimulatory molecule that can enhance antitumor immunity by modulating the proliferation, differentiation, and effector function of tumor-infiltrating T cells, have attracted much attention for their excellent therapeutic effects. In this study, we aimed to evaluate the antitumor efficacy of combined anti-OX40 and hepatitis B core virus-like particles (HBc VLPs) therapy using a mouse colon cancer model. MethodsHumanized B-hOX40 mice were injected subcutaneously with MC38 colon tumor cells and treated with HBc VLPs+anti-hOX40 antibody. Tumor growth was monitored. Flow cytometric analysis was performed to evaluate the populations of T cell subsets in the tumors. ResultsThe combination of anti-OX40 with HBc VLPs resulted in a significant delay in tumor growth, suggesting that a potent antitumor immunity was induced by the combination therapy. Further studies revealed that HBc VLPs+anti-OX40 treatment induced a significant increase in effector T cells (Teffs) and a significant decrease in regulatory T cells (Tregs) in the tumor microenvironment (TME), which accounted for the synergistic antitumor effect of anti-OX40 in combination with HBc VLPs. ConclusionCombination therapy of anti-hOX40 and HBc VLPs provides synergistic antitumor activity in colon cancer-bearing mice, which may represent a potential design strategy for cancer immunotherapy.

523 - Efficacy and safety of amlitelimab (an anti-OX40 ligand antibody) in patients with moderate-to-severe atopic dermatitis: 24-week results from a phase 2b trial (STREAM-AD)

Abstract Introduction/Background Targeting and binding OX40 ligand (OX40L) expressed on antigen-presenting cells may inhibit the persistent immune response that drives atopic dermatitis (AD) pathophysiology. Amlitelimab (SAR445229; KY1005) is a potential first-in-class, fully human, non-depleting anti-OX40L monoclonal antibody that blocks OX40L-OX40 interactions and has shown efficacy and an acceptable safety profile in a Phase 2a trial in adults with moderate-to-severe AD. Here, we present 24-week efficacy and safety results (Part 1) from an ongoing dose-ranging Phase 2b trial. The study remains blinded to individual patient data (Part 2 ongoing). Objectives To evaluate the efficacy and safety of amlitelimab in adults with moderate-to-severe AD. Methods STREAM-AD (NCT05131477) is a 52-week, randomised, double-blinded, placebo-controlled Phase 2b monotherapy trial. This study is designed with 2 parts (double-blind throughout): a 24-week treatment period (Part 1, completed and presented here) and a 36-week maintenance/withdrawal period (Part 2, ongoing). Adults (18 to &amp;lt;75 years; n=390) with moderate-to-severe AD were randomised 1:1:1:1:1 to receive subcutaneous amlitelimab Q4W (250 mg with 500 mg loading dose [LD], n=77; 250 mg without LD, n=78; 125 mg without LD, n=77; or 62.5 mg without LD, n=79) or placebo Q4W (n=79). The primary endpoint was percentage change in Eczema Area and Severity Index (EASI) from baseline at Week 16. Key secondary endpoints included percentage change in EASI at Week 24 and percentage of patients with at least 75% reduction from baseline in EASI (EASI-75), percentage of patients with Investigator Global Assessment response of 0 (clear) or 1 (almost clear) and a reduction from baseline of ≥2 points (IGA 0/1), and proportion of patients with a weekly average reduction of Peak Pruritus Numerical Rating Scale (PP-NRS) ≥4 points from baseline. The primary efficacy analysis included all randomised patients who completed Week 24 or discontinued treatment or study prior to Week 24 visit (n=390), whereas the safety analysis included all treated patients (n=388). Results Treatment with amlitelimab resulted in statistically significant improvements in percentage change in EASI from baseline to Week 16 compared to placebo for all four doses studied. The 250 mg with LD group had the numerically highest response versus placebo at Week 16, with a least-squares mean change from baseline of –32.1% (95% CI: –43.9, –20.3; P&amp;lt;0.0001); the remaining groups without LD had the following responses versus placebo: 250 mg, –27.3 (95% CI: –39.1, –15.6; P&amp;lt;0.0001); 125 mg, –22.2 (95% CI: –34.0, –10.4; P=0.0002); and 62.5 mg, –30.2 (95% CI: –41.9, –18.5; P&amp;lt;0.0001). There were also clinically meaningful improvements in all key secondary efficacy outcome measures, with all amlitelimab dose groups demonstrating nominally significant (P&amp;lt;0.05) efficacy versus placebo for EASI-75, IGA 0/1, and PP-NRS ≥4, except 250 mg (no LD) in IGA 0/1 at Week 16 (P=0.0562). Continued improvements were generally observed through Week 24 in primary and key secondary efficacy outcomes. Amlitelimab was well tolerated across all dose groups, with no safety concerns identified. Conclusions In this dose-ranging Phase 2b trial of amlitelimab in adults with moderate-to-severe AD, amlitelimab demonstrated clinically meaningful efficacy over 24 weeks with an acceptable safety profile across all four dose groups.

Reprogramming macrophage by targeting VEGF and CD40 potentiates OX40 immunotherapy

The low clinical response rate of checkpoint blockades, such as PD-1 and CTLA-4, highlighted the requirements of agonistic antibodies to boost optimal T cell responses. OX40, a co-stimulatory receptor on the T cells, plays a crucial role in promoting T cell survival and differentiation. However, the clinical efficacy of anti-OX40 agonistic antibodies was unimpressive. To explore the mechanism underlying the action of anti-OX40 agonists to improve the anti-tumor efficacy, we analyzed the dynamic changes of tumor-infiltrating immune cells at different days post-treatments using single-cell RNA-sequencing (scRNA-seq). In this study, we found that tumor-infiltrating regulatory T (Treg) cells were reduced after two rounds of anti-OX40 treatment, but the increase of infiltration and activation of CD8+ effector T cells, as well as M1 polarization in the tumor were only observed after three rounds of treatments. Moreover, our group first analyzed the antitumor effect of anti-OX40 treatments on regulating the macrophages and discovered the dynamic changes of vascular endothelial growth factor (VEGF) and CD40 signaling pathways on macrophages, indicating their possibility to being potential combination targets to improve the anti-OX40 agonists efficacy. The combination of VEGFR inhibitors or anti-CD40 agonist antibody with anti-OX40 agonists exhibited more remarkable inhibition of tumor growth. Therefore, the mechanism-driven combination of anti-OX40 agonists with VEGFR inhibitors or anti-CD40 agonists represented promising strategies.

In vivo production of CAR-T cells using virus-mimetic fusogenic nanovesicles

Engineered T cells expressing chimeric antigen receptor (CAR) exhibit high response rates in B-cell malignancy treatments and possess therapeutic potentials against various diseases. However, the complicated ex vivo production process of CAR-T cells limits their application. Herein, we use virus-mimetic fusogenic nanovesicles (FuNVs) to produce CAR-T cells in vivo via membrane fusion-mediated CAR protein delivery. Briefly, the FuNVs are modified using T-cell fusogen, adapted from measles virus or reovirus fusogens via displaying anti-CD3 single-chain variable fragment. The FuNVs can efficiently fuse with the T-cell membrane in vivo, thereby delivering the loaded anti-CD19 (αCD19) CAR protein onto T-cells to produce αCD19 CAR-T cells. These αCD19 CAR-T cells alone or in combination with anti-OX40 antibodies can treat B-cell lymphoma without inducing cytokine release syndrome. Thus, our strategy provides a novel method for engineering T cells into CAR-T cells in vivo and can further be employed to deliver other therapeutic membrane proteins.

Loss of the OX40 Target in Lymphoma Patients after Combining an Anti-OX40 Agonist Antibody with in Situ Vaccination

INTRODUCTION:Previous clinical trials have shown that in situ vaccination using the combination of low-dose radiotherapy and intratumoral injection of CpG, a Toll-like receptor 9 (TLR9) agonist, can elicit T cell immune responses in patients with low grade lymphoma and regression at both the treated and non-treated distal tumor sites in patients with low-grade lymphoma (Brody et al., JCO 2010, Frank et al., Cancer Discovery 2018, Hammerich et al., Nat Med 2019). OX40 is a T cell activating co-receptor, belonging to the TNFR superfamily. Ligation of this receptor by an agonist anti-OX40 antibody leads to enhanced T cell activation of effector CD4 T cells while inhibiting Treg function. In preclinical models, addition of an anti-OX40 antibody to intratumoral CpG cured established tumors (Sagiv-Barfi I, et al. Sci Transl Med. 2018). Intratumoral injection of CpG up-regulated OX40 on CD4 T cells in the microenvironment enhancing the binding of agonistic anti-OX40 antibody that triggered a robust immune response. These results provided the rationale for a clinical trial of in situ vaccination (NCT03410901) using a human IgG1 agonistic anti-OX40 antibody (BMS-986178). STUDY:Fourteen patients with low-grade lymphoma received low-dose (2Gy x 2) radiotherapy to a single tumor site followed by 5 weekly intratumoral injections of 2 mg CpG-ODN (SD-101, TriSalus Life Sciences) and 3.75 mg anti-OX40 antibody into the same site. 40mg of anti-OX40 was administered intravenously starting on day 2 and continuing every 4 weeks for a total of 6 infusions. Therapy was well tolerated with no dose-limiting toxicities. Response to therapy was assessed using the revised Lugano criteria (Cheson et al., JCO 2014) based on CT scans at 12, 24, 48, 72, and 96 weeks. Fine needle aspirates (FNA) were performed at both the injected and a non-injected site outside the radiation field prior to, and at 1 and 6 weeks after initiation of treatment. Cells were analyzed by flow cytometry and droplet-based single-cell RNA sequencing to determine population dynamics, response to therapy as well as antibody binding and target occupancy by the anti-OX40 antibody. RESULTS:Of the 14 patients enrolled, 1 patient attained a partial response (PR), while 9 had stable disease (SD) and 4 had disease progression (PD) as their best overall response. Investigation into the binding of the treatment antibody and target occupancy by flow cytometry showed saturation of all the OX40 sites on CD4 T cells by week 6 at both the injected and non-injected tumors. However, further investigation also showed there was significantly less OX40 on the cell surface after treatment, suggesting a loss of the antibody target (Figure 1). This loss was reproduced by in vitro assays where activated blood CD4 T cells exhibited a loss of cell surface OX40 when cultured with BMS-986178. Additionally, Quigley et al ( Clin Cancer Res 2019) previously showed that an OX40 receptor occupancy of greater than 40% led to a loss of target in mice and in blood T cells of solid tumor patients. We further observed that the loss of cell surface OX40 occurred in all CD4 T subsets, including effector CD4 T cells and T Regulatory cells (Tregs). This result contrasted with our in vivo and in vitro findings in successful therapeutic mouse models where we did not observe this loss of cell surface OX40 on effector CD4 T cells after treatment with a mouse-specific anti-OX40 agonist antibody. C ONCLUSION: Our observations suggest that treatment with an agonistic anti-OX40 antibody induced a loss of OX40 on the cell surface of effector CD4 T cells in the tumor microenvironment. Fewer molecules of OX40 receptor may have constrained the efficacy of subsequent anti-OX40 infusions and may explain why the clinical responses observed in this study were lower than observed in our past clinical trials of in situ vaccination.

Tumor-derived autophagosome vaccines combined with immune adjuvants mediate antitumor immune responses via the neoantigen pathway.

Vaccines composed of autophagosomes derived from tumor cells called DRibbles (DRiPs-containing blebs) are involved in the cross-presentation of tumor antigens, thus inducing cross-reactive T-cell responses against the tumor. Compared with traditional tumor lysate vaccines, autophagosome vaccines were found to be better sources of multiple tumor-associated antigens (TAAs) that activate antigen-specific T-cells. However, the involvement of tumor neoantigens in the immune responses of autophagosome vaccines remains unclear. The present study showed that exogenous autophagosome vaccines (DRibbles) combined with immune adjuvants (anti-OX40 antibody and ATP) can effectively activate functional T cells in vitro. Importantly, the combination of exogenous tumor-derived autophagosome vaccines and immune adjuvants was found to induce tumor regression in B16F10 and 4T1 tumor-bearing mice. The combination of autophagosome-enriched DRibbles with anti-OX40 antibody and ATP also exhibited optimal immune stimulation and antitumor efficiency in vivo. The effectiveness of exogenous DRibble vaccines was mainly due to their enhancement of tumor immunogenicity by increasing the presentation and release of tumor neoantigens. These findings suggest that this immunotherapeutic method may be effective in the treatment of cancer.

Phase 2b randomized trial of OX40 inhibitor telazorlimab for moderate-to-severe atopic dermatitis

Telazorlimab is a humanized anti-OX40 monoclonal antibody being studied for treatment of T-cell-mediated diseases. This randomized, placebo-controlled, phase 2b dose-range finding study investigated efficacy, safety, pharmacokinetics, and immunogenicity of telazorlimab in subjects with atopic dermatitis. In this 2-part study (NCT03568162), adults (≥18 years) with moderate-to-severe disease were randomized to various regimens of subcutaneous telazorlimab or placebo for 16 weeks' blinded treatment, followed by 38 weeks' open-label treatment and 12 weeks' drug-free follow-up. Telazorlimab treatment groups (following a loading dose) in part 1 were 300 mg every 2 weeks; 300 mg every 4 weeks; or 75 mg every 4 weeks. Part 2 evaluated telazorlimab 600 mg every 2 weeks. The primary end point was percentage change from baseline in Eczema Area and Severity Index (EASI) at week 16. Safety assessments included incidence of treatment-emergent adverse events. The study randomized 313 subjects in part 1 and 149 in part 2. At 16 weeks, the least squares mean percentage change from baseline in EASI was significantly greater in subjects receiving telazorlimab 300 mg every 2 weeks (part 1) and 600 mg every 2 weeks (part 2) versus placebo (-54.4% vs -34.2% for part 1 and -59.0% vs -41.8% for part 2, P= .008 for both). Telazorlimab was well tolerated, with similar distribution of adverse events between telazorlimab- and placebo-treated subjects in both part 1 and part 2. Telazorlimab, administered subcutaneously at 300 mg every 2 weeks or 600 mg every 2 weeks following a loading dose, was well tolerated and induced significant and progressive clinical improvement in adults with moderate-to-severe atopic dermatitis.

227 Efficacy and safety of amlitelimab (an anti-OX40 ligand antibody) in patients with moderate-to-severe atopic dermatitis (AD): 24-week results from a Phase 2b trial (STREAM-AD)

227 Efficacy and safety of amlitelimab (an anti-OX40 ligand antibody) in patients with moderate-to-severe atopic dermatitis (AD): 24-week results from a Phase 2b trial (STREAM-AD)

Age-induced changes in anti-tumor immunity alter the tumor immune infiltrate and impact response to immuno-oncology treatments.

Immuno-oncology (IO) research relies heavily on murine syngeneic tumor models. However, whilst the average age for a cancer diagnosis is 60 years or older, for practical purposes the majority of preclinical studies are conducted in young mice, despite the fact that ageing has been shown to have a significant impact on the immune response. Using aged (60-72 weeks old) mice bearing CT26 tumors, we investigated the impact of ageing on tumor growth as well as the immune composition of the tumor and peripheral lymphoid organs. We found many differences in the immune cell composition of both the tumor and tumor-draining lymph node between aged and young mice, such as a reduction in the naïve T cell population and a decreased intratumoral CD8/Treg ratio in aged animals. We hypothesized that these differences may contribute to impaired anti-cancer immune responses in aged mice and therefore assessed the anti-tumor efficacy of different IO therapies in aged mice, including both co-stimulation (using an anti-OX40 antibody) and immune checkpoint blockade (using anti-PD-L1 and anti-CTLA-4 antibodies). Whilst aged mice retained the capacity to generate anti-tumor immune responses, these were significantly attenuated when compared to the responses observed in young mice. These differences highlight the importance of age-related immunological changes in assessing and refining the translational insights gained from preclinical mouse models.

BGB-A445, a novel non-ligand-blocking agonistic anti-OX40 antibody, exhibits superior immune activation and antitumor effects in preclinical models.

OX40 is a costimulatory receptor that is expressed primarily on activated CD4+, CD8+, and regulatory T cells. The ligation of OX40 to its sole ligand OX40L potentiates T cell expansion, differentiation, and activation and also promotes dendritic cells to mature to enhance their cytokine production. Therefore, the use of agonistic anti-OX40 antibodies for cancer immunotherapy has gained great interest. However, most of the agonistic anti-OX40 antibodies in the clinic are OX40L-competitive and show limited efficacy. Here, we discovered that BGB-A445, a non-ligand-competitive agonistic anti-OX40 antibody currently under clinical investigation, induced optimal T cell activation without impairing dendritic cell function. In addition, BGB-A445 dose-dependently and significantly depleted regulatory T cells in vitro and in vivo via antibody-dependent cellular cytotoxicity. In the MC38 syngeneic model established in humanized OX40 knock-in mice, BGB-A445 demonstrated robust and dose-dependent antitumor efficacy, whereas the ligand-competitive anti-OX40 antibody showed antitumor efficacy characterized by a hook effect. Furthermore, BGB-A445 demonstrated a strong combination antitumor effect with an anti-PD-1 antibody. Taken together, our findings show that BGB-A445, which does not block OX40-OX40L interaction in contrast to clinical-stage anti-OX40 antibodies, shows superior immune-stimulating effects and antitumor efficacy and thus warrants further clinical investigation.

BAT6026, a novel anti-OX40 antibody with enhanced antibody dependent cellular cytotoxicity effect for cancer immunotherapy.

OX40 (CD134), a member of the TNF receptor superfamily, is a widely studied costimulatory immune checkpoint. Several OX40 agonistic antibodies are in the clinical stage for cancer treatment, among which PF-04518600 is the leader and currently in phase II trial. It has been recognized that one potential mode of action for anti-OX40 antibodies is the deletion of intratumoral Tregs. Thus, a novel human anti-OX40 antibody, BAT6026, was generated with enhanced antibody dependent cellular cytotoxicity (ADCC) via fucose deletion to strengthen its Treg depletion activity. This characteristic of BAT6026 differentiates it from other previously reported anti-OX40 antibodies in the field of tumor therapy. The affinity of BT6026 to OX40 was 0.28nM, approximately 8 times stronger than that of PF-04518600. BAT6026 effectively competed for the binding of ligand OX40L to OX40, whereas PF-04518600 only partially competed. Moreover, compared to PF-04518600, BAT6026 activated T cells more effectively when clustered by FcγRs engagement and stimulated SEB-pretreated PBMCs to secrete IL-2 cytokines in vitro. In addition, BAT6026 demonstrated stronger anti-tumor activity than PF-04518600 in an OX40-humanized mouse MC38 tumor model. BAT6026 also showed a significantly synergistic effect on tumor inhibition when combined treatment with PD-1 antibody. Analysis of tumor-infiltrating T cells revealed that BAT6026 treatment significantly reduced Treg cells and increased CD8+ T cells in tumor. Preclinical safety assessment in non-human primates demonstrated a good safety profile for BAT6026. Together these data warrant further development of BAT6026 into clinical trials for patients with cancer.

Photothermic therapy with cuttlefish ink-based nanoparticles in combination with anti-OX40 mAb achieve remission of triple-negative breast cancer.

Immunostimulatory monoclonal antibodies (IS-mAb) have been proven to enhance the therapeutic effectiveness of various anticancer therapy. In the present investigation, we launched a separate combinational therapy for the treatment of triple-negative breast cancer (TNBC) using cuttlefish ink-based nanoparticles (CINPs) for photothermal therapy (PTT) and anti-OX40 antibody. Our goal was to increase the therapeutic response to the disease. CINPs were characterized by their physicochemical properties, which revealed that they had a hydrodynamic diameter ranging from 128 to 148nm, a negative surface charge, and a high photothermal conversion efficiency under both in vitro and in vivo settings. In TNBC model, we evaluated the therapeutic effectiveness of the following groups: CINP-PTT+anti-OX40 Ab (G1), CINPs-PTT (G2), CINPs+anti-OX40 Ab (G3), anti-OX40 (G4) or PBS (G5). In each case, we assessed the efficacy of these groups against one another. The intratumor administration of all of the substances and therapies was performed. CINP-PTT+anti-OX40 Ab and CINP+anti-OX40 Ab (particularly CINP-PTT+anti-OX40 Ab) induced significant tumor regression in treated (breast) and non-treated (flank) tumor, and completely inhibited lung metastasis, thereby inducing a higher survival rate in mice in comparison to CINP-PTT, anti-OX40 Ab, or PBS. This was the case because in CINPs-treated tumors, particularly those treated with CINPs-PTT, intratumoral injection of CINPs increased the frequency of OX40, CD8 double-positive T cells. CINPs improved the conversion of the macrophage phenotype from M2 to M1 in vitro, which is significant from an immunological point of view. In addition, anti-OX40 Ab combined with CINPs or, more specifically, CINPs-PPT produced a larger frequency of preexisting and newly formed tumor-specific CD8 T cells, as well as an enhanced frequency of CD8 T cells infiltrating non-treated tumors, in comparison to respective monotherapies. When the data were taken into consideration as a whole, it seemed that CINPs-based PTT may effectively enhance the antitumor response effectiveness of anti-OX40 Ab.

Antitumor efficacy of multi-target in situ vaccinations with CpG oligodeoxynucleotides, anti-OX40, anti-PD1 antibodies, and aptamers.

To overcome immune tolerance to cancer, the immune system needs to be exposed to a multi-target action intervention. Here, we investigated the activating effect of CpG oligodeoxynucleotides (ODNs), mesyl phosphoramidate CpG ODNs, anti-OX40 antibodies, and OX40 RNA aptamers on major populations of immunocompetent cells ex vivo. Comparative analysis of the antitumor effects of in situ vaccination with CpG ODNs and anti-OX40 antibodies, as well as several other combinations, such as mesyl phosphoramidate CpG ODNs and OX40 RNA aptamers, was conducted. Antibodies against programmed death 1 (PD1) checkpoint inhibitors or their corresponding PD1 DNA aptamers were also added to vaccination regimens for analytical purposes. Four scenarios were considered: a weakly immunogenic Krebs-2 carcinoma grafted in CBA mice; a moderately immunogenic Lewis carcinoma grafted in C57Black/6 mice; and an immunogenic A20 B cell lymphoma or an Ehrlich carcinoma grafted in BALB/c mice. Adding anti-PD1 antibodies (CpG+αOX40+αPD1) to in situ vaccinations boosts the antitumor effect. When to be used instead of antibodies, aptamers also possess antitumor activity, although this effect was less pronounced. The strongest effect across all the tumors was observed in highly immunogenic A20 B cell lymphoma and Ehrlich carcinoma.