231 Molecular insights on safety and anti-tumor activity of a non-irAE-inducing anti-CTLA-4 monoclonal antibody ONC-392

BackgroundAnti-CTLA-4 antibodies have brought about limited clinical benefit because severe toxicity limits dosing levels and/or duration. We used CTLA-4 knockin mice to screen for antibodies with higher anti-tumor activity but lower autoimmunity. We have revealed that the key for better safety and preclinical efficacy is preservation of CTLA-4 for immune tolerance and intratumorial Treg depletion. Our work established that, independent of blocking activities, mAbs that preserve CTLA-4 recycling maintain the physiological immune tolerance checkpoint function while allowing more efficient and selective elimination of tumor-infiltrating regulatory T cells, resulting in highest efficacy and lowest toxicity and was thus developed for clinical testing of all antibodies tested.1–6 The antibody with best safety and efficacy profile, ONC-392 was developed for clinical testing. The first-in human studies showed that ONC-392 is safe and well tolerated. Remarkably, no irAE has been reported among patients who has received repeated dosing of 3.0 mg/kg and 10.0 mg/kg of ONC-392. The molecular and cellular characterization of ONC-392 will be presented.MethodsIn vitro binding and disassociation assay were determined between pH 4.0–7.0. The intracellular traffic of both antibodies and CTLA-4 molecules were visualized by confocal microscopy. The binding to human and mouse FcgRI, IIA, IIB, and III (A), FcRn as well as mouse FcgRIV were evaluated by surface plasmon resonance (SPR). Depletion of regulatory T cells in tumor and lymphoid tissues were determined by flow cytometry.ResultsONC-392 is a pH-sensitive antibody that preserves CTLA-4 recycling. By preserving cell surface CTLA-4, Onco-392 preserves immune tolerance. Preserving CTLA-4 on tumor-infiltrating Treg contribute to more effective immunotherapy. In addition to its unique feature of pH sensitive binding, OncoC4 also have several important features in Fc. ONC-392 shown comparable binding to human FcgRI and IIIA as wild-type IgG1s. As expected from the mutations introduced, ONC-392 show about 6 fold higher affinity for FcRn than wild-type IgG1. Interestingly, ONC-392 has shown 7–10-fold reduction to FcgRIIB, which is generally considered to be a negative signaling FcR. ONC-392 binding to mouse FcgRI-IV was lower that WT IgG1.ConclusionsUnlike other clinical anti-CTLA-4 antibodies, ONC-392 preserves CTLA-4 recycling and thus Treg function in the peripheral tissues. The higher cell surface CTLA-4 allows more efficient Treg depletion in the tumor microenvironment. In addition, despite reduced binding to mouse activating Fc?RI, III/IV, ONC-392 was more effective in intratumor Treg depletion in the mice. Therefore, lacking negative signaling from Fc?RIIB may also contribute to its anti-tumor activity.Trial RegistrationNCT04140526ReferencesDu X, et al. Uncoupling therapeutic from immunotherapy-related adverse effects for safer andeffective anti-CTLA-4 antibodies in CTLA4 humanized mice. Cell Res 2018;28:433–447.Du X, et al. A reappraisal of CTLA-4 checkpoint blockade in cancer immunotherapy. Cell Res 2018;28:416–432.Liu Y, Zheng P. How does an anti-CTLA-4 antibody promote cancer immunity? Trends Immunol 2018;39:953–956.Zhang Y, et al. Hijacking antibody-induced CTLA-4 lysosomal degradation for safer and more effective cancer immunotherapy. Cell Res 2019;29:609–627.Liu Y, Zheng P. Preserving the CTLA-4 checkpoint for safer and more effective cancer immunotherapy. Trends Pharmacol Sci 2020;41(1):4–12.Zhang P, et al. Mechanism- and immune landscape-based ranking of therapeutic responsiveness of 22 major human cancers to next generation anti-CTLA-4 antibodies. Cancers 2020;12:284.

Download Full-text

Targeting MHC-linked wild type p53 with TCR mimic single chain diabody for cancer immunotherapy.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.2524 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. 2524-2524

Author(s):

Suman Paul ◽

Jacqueline Douglass ◽

Annika Schaefer ◽

Emily Han-Chung Hsiue ◽

Alexander Pearlman ◽

...

Keyword(s):

T Cells ◽

Cell Surface ◽

Cancer Immunotherapy ◽

Cell Killing ◽

Human Cells ◽

Wild Type ◽

Single Chain ◽

Nsg Mice ◽

Wild Type P53

2524 Background: Increased tumor suppressor protein p53 expression is observed in a wide range of human cancers. As a result there is intense interest in targeting p53 for cancer therapy. Intracellular p53 is inaccessible to therapeutic antibodies that bind cell surface proteins. However, intracellular proteins including p53 are degraded into peptides that are presented on cell surface in association with HLA class I molecules. Thus p53 peptide-HLA (p53-HLA) complexes can be antibody targets. Methods: Using phage display we identified a novel anti-p53-HLA single chain variable fragment (scFv) clone-43 that recognizes a wild-type p53 10-mer epitope bound to HLA-A*2402. By coupling our clone-43 scFv with an anti-CD3 scFv, we generated a single chain diabody (scDb) designed to activate T-cells against p53-expressing target cells. Results: In-vitro co-culture of clone-43 scDb with donor human T-cells and p53 expressing SIG-M5 cancer cells results in SIG-M5 cell killing and concomitant T-cell interferon gamma (IFNγ) release. In contrast, similar co-culture with SIG-M5 p53-knock out (KO) cells showed no cell killing and minimal IFNγ release demonstrating specificity of clone-43 to p53 expressing cells. Additionally, in-vivo growth of p53 expressing SW480 cancer cell xenografts in NSG mice was completely terminated by clone-43 scDb injections. A major concern for wild-type p53 epitope targeting is potential on-target off-tumor effect on non-cancerous tissue. We observed significant in-vitro clone-43 scDb mediated killing of human HLA-A*24:02 peripheral blood mononuclear cells. To better evaluate effect of clone-43 scDb on non-neoplastic human cells, we engrafted HLA-A*24:02 human CD34+ hematopoietic stem cells into NSG mice to generate a humanized mouse model with circulating mature human CD45+ cells. Clone-43 scDb treatment resulted in selective depletion of circulating human cells while the same cells persisted in mice treated with unrelated control scDb. Conclusions: Our observation that immune targeting of wild-type p53 epitope results in significant off-tumor hematopoietic cell death is contrary to previously published reports and carries important implications for future anti-p53 antibody and vaccine design for cancer immunotherapy.

Download Full-text

Regulatory T cells in B-cell-deficient and wild-type mice differ functionally and in expression of cell surface markers

Immunology ◽

10.1111/imm.12410 ◽

2015 ◽

Vol 144 (4) ◽

pp. 598-610 ◽

Cited By ~ 6

Author(s):

Jason S. Ellis ◽

Helen Braley-Mullen

Keyword(s):

T Cells ◽

Regulatory T Cells ◽

Cell Surface ◽

B Cell ◽

Surface Markers ◽

Cell Surface Markers ◽

Wild Type

Download Full-text

250 SEA-TGT is a nonfucosylated antibody with distinct and amplified effector function activity that leverages the dependencies of anti-TIGIT anti-tumor activity upon Fc? R engagement

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0250 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A271-A271

Author(s):

Alyson Smith ◽

Weiping Zeng ◽

William Siegall ◽

Bryan Grogan ◽

Jane Haass ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Activation ◽

Memory T Cells ◽

Cd8 T Cell ◽

Wild Type ◽

Treg Depletion ◽

The Impact ◽

Anti Tumor Activity ◽

Cell Functionality

BackgroundTIGIT is an immunoregulatory receptor expressed on activated and memory T cells, T regulatory cells (Tregs), and NK cells. TIGIT binding to CD155 and CD112 on tumor cells drives an inhibitory signal resulting in decreased T cell functionality. TIGIT targeting has been reported to release these inhibitory signals, drive Treg depletion, augment CD8 T cell generation, and promote anti-tumor responses.MethodsTo evaluate the impact of antibody backbone on anti-TIGIT action three distinct antibodies with differential backbone effector functions, wild type, Fc(gamma)R null (LALA), and Fc(gamma)R enhanced (nonfucosylated, SEA-TGT), were incorporated onto a human anti-TIGIT antibody and assessed. The nonfucosylated SEA-TGT backbone was distinct from the LALA and wild type backbone through increased binding to activating FcyRIIIa receptor while concomitantly decreasing binding to the inhibitory Fc(gamma)RIIb receptor.ResultsIndependent of backbone all TIGIT antibodies blocked ligand binding and restored CD226 signaling. The effector null backbone neither mediated Treg depletion nor naïve or memory CD8 T cell activation. However, the effector enhanced SEA-TGT significantly increased Treg depletion and activation of CD8 T cells over the comparator wild type anti-TIGIT antibody. The enhanced SEA-TGT also induced innate cell activation not seen with the other backbones. These in vitro results translated to curative in vivo anti-tumor activity in multiple syngeneic models as a single agent. Again, the effector null antibody was inactive in all models whereas the effector enhanced SEA-TGT drove curative responses beyond those seen with the standard wild type backbone. Increased activity correlated with a slight decrease in intra-tumoral Tregs and increases in CD8 memory T cells and innate cell activations. Anti-tumor response was associated with generation of long-term, antigen-specific immunity that resulted in complete tumor rejection upon tumor re-challenge.ConclusionsCollectively, these data indicate that modulation of CD8 T cell functionality is not solely through alterations in the TIGIT/CD226 signaling axis and that our nonfucosylated Fc?R enhanced antibody uniquely activates both adaptive and innate arms of the immune system for maximal CD8 T cell responses. They also underscore the anti-tumor therapeutic potential of a nonfucosylated TIGIT targeting antibody (SEA-TGT) as a monotherapy agent and in combination with PD(L)1 agents. We have initiated a phase 1 trial testing the safety and activity of SEA-TGT in patients with advanced solid tumors and select lymphomas (NCT04254107).Trial RegistrationNCT04254107Ethics ApprovalAnimals studies were approved by and conducted in accordance with Seattle Genetics Institutional Care and Use Committee protocol #SGE-029.

Download Full-text

Faculty Opinions recommendation of Cell contact-dependent immunosuppression by CD4(+)CD25(+) regulatory T cells is mediated by cell surface-bound transforming growth factor beta.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1000961.10054 ◽

2002 ◽

Author(s):

Bruce Blazar

Keyword(s):

T Cells ◽

Growth Factor ◽

Regulatory T Cells ◽

Cell Surface ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Cell Contact ◽

Growth Factor Beta

Download Full-text

Faculty Opinions recommendation of Immune tolerance. Regulatory T cells generated early in life play a distinct role in maintaining self-tolerance.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725399019.793507728 ◽

2015 ◽

Author(s):

Rachel R Caspi ◽

Sohyun Sophia Jeon

Keyword(s):

T Cells ◽

Regulatory T Cells ◽

Immune Tolerance ◽

Self Tolerance ◽

Distinct Role

Download Full-text

Functional control of regulatory T cells and cancer immunotherapy

Seminars in Cancer Biology ◽

10.1016/j.semcancer.2005.11.004 ◽

2006 ◽

Vol 16 (2) ◽

pp. 106-114 ◽

Cited By ~ 32

Author(s):

Rong-Fu Wang

Keyword(s):

T Cells ◽

Regulatory T Cells ◽

Cancer Immunotherapy ◽

Functional Control

Download Full-text

Low-dose IL-2 therapy limits the reduction in absolute numbers of circulating regulatory T cells in rheumatoid arthritis

Therapeutic Advances in Musculoskeletal Disease ◽

10.1177/1759720x211011370 ◽

2021 ◽

Vol 13 ◽

pp. 1759720X2110113

Author(s):

Sheng-Xiao Zhang ◽

Jia Wang ◽

Cai-Hong Wang ◽

Rui-Huan Jia ◽

Ming Yan ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

T Cells ◽

Side Effects ◽

Regulatory T Cells ◽

Disease Activity ◽

Immune Tolerance ◽

Low Dose ◽

Fold Increase ◽

Plain Language ◽

T Subsets

Background: Circulating regulatory T cells (Tregs) are responsible for mediating immune tolerance and maintaining immunological homeostasis. Decreases in Tregs may be involved in the onset of rheumatoid arthritis (RA). Low-dose interleukin-2 (IL-2) has been considered for the treatment of inflammatory diseases mediated by T cells. This study focused on the status of circulating CD4+T subsets and the clinical feasibility of IL-2 therapies in patients with RA. Methods: The subjects included 888 patients with RA and 100 healthy controls (HCs); 233 RA patients received IL-2 treatment with 0.5 million international units (MIU)/day from days 1 through 5. The demographic features, disease activity, and levels of CD4+T cells measured by modified flow cytometry were collected in all RA patients before and after treatment. Results: RA patients had lower absolute Treg counts (but not Th17) compared with HCs, which was associated with disease activity; previously treated RA patients had the fewest circulating Tregs ( p < 0.05). Patients treated with low-dose IL-2 had a three-fold increase in absolute anti-inflammatory Treg counts, as well as a two-fold increase in the other CD4+T subsets. Moreover, post-treatment levels of markers of disease activity in RA patients treated with IL-2 were significantly lower than the baseline values ( p < 0.001), with no apparent side effects. Conclusion: Decreased absolute counts of circulating CD4+T lymphocyte subsets were observed in patients with RA. Circulating Tregs, which mediate immune tolerance, may be involved in the pathogenesis and progression of RA; however, this was ameliorated by low-dose IL-2, without obvious side effects. Plain language summary Low-dose IL-2 treatment for rheumatoid arthritis • Circulating Tregs may be involved in the pathogenesis and progression of RA. • The absolute count of Tregs was significantly correlated with disease activity measures. • Low-dose IL-2 was able to effectively expade Tregs and help for RA patients’ symptoms remission without evaluated side effects.

Download Full-text