Cell-mediated Antitumor Responses Research Articles

Novel insights into paclitaxel’s role on tumor-associated macrophages in enhancing PD-1 blockade in breast cancer treatment

BackgroundTriple-negative breast cancer (TNBC) poses unique challenges due to its complex nature and the need for more effective treatments. Recent studies showed encouraging outcomes from combining paclitaxel (PTX) with programmed...

CD155 blockade enhances allogeneic natural killer cell-mediated antitumor response against osteosarcoma.

Allogeneic bone marrow transplant (alloBMT) is curative for hematologic malignancies through the graft-versus-tumor (GVT) effect but has been ineffective for solid tumors like osteosarcoma (OS). OS expresses CD155 which interacts strongly with inhibitory receptors TIGIT and CD96 but also binds to activating receptor DNAM-1 on natural killer (NK) cells. CD155 has never been targeted after alloBMT. Combining adoptively transferred allogeneic NK (alloNK) cells with CD155 blockade after alloBMT may enhance a GVT effect against OS. Murine NK cells were activated and expanded ex vivo with soluble IL-15/IL-15Rα. AlloNK and syngeneic NK (synNK) cell phenotype, cytotoxicity, cytokine production, and degranulation against CD155-expressing murine OS cell line K7M2 were assessed in vitro. Mice bearing pulmonary OS metastases underwent alloBMT and alloNK cell infusion with anti-CD155 either before or after tumor induction, with select groups receiving anti-DNAM-1 pretreated alloNK cells. Tumor growth, GVHD and survival were monitored, and differential gene expression of lung tissue was assessed by RNA microarray. AlloNK cells exhibited superior cytotoxicity against CD155-expressing OS compared to synNK cells, and this activity was enhanced by CD155 blockade. CD155 blockade increased alloNK cell degranulation and interferon gamma production through DNAM-1. In vivo, CD155 blockade with alloNK infusion increased survival when treating OS that relapsed after alloBMT. No benefit was seen for treating established OS before alloBMT. Treatment with combination CD155 and anti-DNAM-1 pretreated alloNK ameliorated survival and tumor control benefits seen with CD155 blockade alone. RNA microarray showed mice treated with alloNK and CD155 blockade had increased expression of cytotoxicity genes and the NKG2D ligand H60a, whereas mice treated with anti-DNAM-1 pretreated alloNK cells resulted in upregulation of NK cell inhibitory receptor genes. Whereas blocking DNAM-1 on alloNK abrogated cytotoxicity, blocking NKG2D had no effect, implying DNAM-1:CD155 engagement drives alloNK activation against OS. These results demonstrate the safety and efficacy of infusing alloNK cells with CD155 blockade to mount a GVT effect against OS and show benefits are in part through DNAM-1. Defining the hierarchy of receptors that govern alloNK responses is critical to translating alloNK cell infusions and immune checkpoint inhibition for solid tumors treated with alloBMT. Allogeneic bone marrow transplant (alloBMT) has yet to show efficacy in treating solid tumors, such as osteosarcoma (OS). CD155 is expressed on OS and interacts with natural killer (NK) cell receptors, such as activating receptor DNAM-1 and inhibitory receptors TIGIT and CD96 and has a dominant inhibitory effect on NK cell activity. Targeting CD155 interactions on allogeneic NK cells could enhance anti-OS responses, but this has not been tested after alloBMT. CD155 blockade enhances allogeneic natural killer cell-mediated cytotoxicity against OS and improved event-free survival after alloBMT in an in vivo mouse model of metastatic pulmonary OS. Addition of DNAM-1 blockade abrogated CD155 blockade-enhanced allogeneic NK cell antitumor responses. These results demonstrate efficacy of allogeneic NK cells combined with CD155 blockade to mount an antitumor response against CD155-expressing OS. Translation of combination adoptive NK cell and CD155 axis modulation offers a platform for alloBMT treatment approaches for pediatric patients with relapsed and refractory solid tumors.

Deciphering CD4+ T cell-mediated responses against cancer.

It'sbeen long thought that CD8+ cytotoxic T cells play a major role in T cell-mediated antitumor responses, whereas CD4+ T cells merely provide some assistance to CD8+ T cells as the "helpers."In recent years, numerous studies support the notion that CD4+ T cells play an indispensable role in antitumor responses. Here, we summarize and discuss the current knowledge regarding the roles of CD4+ T cells in antitumor responses and immunotherapy, with a focus on the molecular and cellular mechanisms behind these observations. These new insights on CD4+ T cells may pave the way to further optimize cancer immunotherapy.

WTAP enhances the instability of SYTL1 mRNA caused by YTHDF2 in bladder cancer.

Bladder cancer (BCa) is the most frequent type of cancer in humans. The association between m6A modification and the anti-tumor effects of natural killer (NK) cells has been described in BCa. This study intended to investigate the implications of m6A regulators in modulating SYTL1 expression in BCa and the association with the anti-tumor effects of NK cells. The prognostic role of SYTL1 in BCa was investigated using bioinformatics analysis, and the correlation between SYTL1 expression and NK cells was analyzed. The effects of SYTL1 on the anti-tumor response of NK-92 cells were examined by RT-qPCR, cytotoxicity, western blot, and ELISA assays. The relationships among WTAP, YTHDF2, and SYTL1 were investigated by RT-qPCR, RIP-qPCR, ELISA, and actinomycin D treatment. Finally, the effects of WTAP and SYTL1 on BCa tumor growth and the anti-tumor response of NK cells were verified in vivo. SYTL1 was reduced in BCa tissues and had a prognostic significance, which was related to NK cell-mediated anti-tumor responses. NK-92 cells produced toxicity to BCa cells, which was further enhanced by SYTL1 overexpression in BCa cells through prompting LDH, NKG2D, NKp30, and NKp44 and IFN-γ levels. WTAP enhanced the degradation of the SYTL1 mRNA by YTHDF2. WTAP and YTHDF2 impaired the anti-tumor response of NK cells in BCa. SYTL1 inhibited the BCa progression in mice while enhancing the anti-tumor response of NK cells. WTAP inhibited the anti-tumor response of NK cells to BCa cells by promoting the degradation of SYTL1 mRNA through YTHDF2-mediated m6A methylation.

Safety and efficacy of belantamab mafodotin with pembrolizumab in patients with relapsed or refractory multiple myeloma.

Belantamab mafodotin (belamaf) has shown promising antimyeloma activity in relapsed or refractory multiple myeloma (RRMM) as a single agent. It was hypothesized that its multimodal activity may be enhanced by programmed cell death protein 1 pathway inhibition and activation of T cell-mediated antitumor responses. This study investigated the efficacy and safety of belamaf with pembrolizumab in patients with RRMM. DREAMM-4 (NCT03848845) was an open-label, single-arm, phase 1/2 study divided into dose-escalation (part 1) and dose-expansion (part 2) phases. Patients were ≥18 years old with ≥3 prior lines of therapy including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 agent. Patients received belamaf (2.5 or 3.4 mg/kg, part 1; 2.5 mg/kg, part 2) and 200 mg pembrolizumab for ≤35 cycles. Of 41 enrolled patients, 34 (n=6 part 1, n=28 part 2) who received 2.5 mg/kg belamaf plus pembrolizumab were included in this final analysis. Sixteen patients (47%) achieved an overall response. Minimal residual disease negativity was achieved in three of 10 patients who had very good partial response or better. Five of eight patients who had prior anti-B-cell maturation antigen therapy achieved partial response or better, including two who had B-cell maturation antigen-refractory disease. Common grade ≥3 adverse events were keratopathy (38%) and thrombocytopenia (29%). Despite belamaf-related ocular events, quality-of-life measures remained stable over time. No new safety signals were observed. The results of DREAMM-4 demonstrated clinical activity and a favorable safety profile of belamaf plus pembrolizumab in patients with RRMM. This trial is registered at www. gov as NCT03848845.

Abstract LB426: Evidence for a role of GPR35 in IDO1-mediated tumor immune escape by regulating Hippo-YAP pathway

Abstract IDO1 is an immune checkpoint regulator and mediator of tumor immune evasion (1). The cellular and molecular mechanisms of IDO1-mediated immune suppression are not fully understood. We describe here that GPR35, the putative receptor for kynurenic acid (KYNA), a metabolite of IDO1-mediated tryptophan catabolism, couples to Hippo-YAP pathway. GPR35 activation, either by overexpression or by treatment with tryptophan metabolites resulted in Hippo inactivation and YAP-directed transcription via TEAD family of transcription factors. Recently, YAP is found to be essential for tumor immune escape. Yap1 deficiency in T-lineage-specific knockout mice, or by dosing a YAP inhibitor, impairs Treg formation and function, leading to tumor growth inhibition (2). YAP also plays an inhibitory role in CD8 T cell function, especially in activated CTL usually found in the TME [3,4]. Through medicinal chemistry design and a structure-vs-activity relationship study effort, we discovered a GPR35-selective inhibitor, here termed TMER1i. TMER1i potently blocks GPR35 in Hippo suppression and YAP activation. We showed that GPR35 is expressed in the T-cell lineage of the immune cells including naïve CD4 T cells, Treg and CD8 T cells. Treatment of purified human naïve CD4 T cells with anti-CD3/anti-CD28 under an IDO1+ TME-like culture condition in vitro induced a robust T cell activation and differentiation toward Treg phenotype, as shown previously using mouse naïve CD4 T cells by others (5). Importantly, TMER1i efficiently blocked the Treg differentiation under these conditions. When dosed in human-PBMC reconstituted NCG mice bearing HT29 tumors, TMER1i dose-dependently increased the infiltration of human CD8 T cells within tumors in a statistically significant manner, and a trending lower Treg cell infiltration, accompanied by a tumor growth inhibition. qPCR analysis of the HT29 tumors grown in the PBMC-NCG mice indicated that IDO1 was highly expressed in the tumors. These results indicated that GPR35 selective inhibitor TMER1i enhanced an anti-tumor immune activity in an IDO1+ tumor microenvironment. Taken together, these studies provided evidence for a role of GPR35 in mediating IDO1 immune suppression by regulating Hippo-YAP pathway in Treg and CTL cells in the immune system. Thus, GPR35 inhibitors have a potential to be novel immuno-therapeutic agents effective in treating patients with IDO1-positive tumors. Reference1.Munn, DH, and Mellor, AL. (2007) Indoleamine 2,3-dioxygenase and tumor-induced tolerance. J. Clin. Invest. 117:1147-11542.Ni, X. et al. Yap is essential for Treg-mediated suppression of antitumor Immunity. Cancer Discovery 2018; 8:1026-10433.Lebid, A. et al. (2020) YAP attenuates CD8 T cell-mediated anti-tumor response. Frontiers in Immunology 11:1-84.Stampouloglou, E. et al. (2020) YAP suppresses T-cell function and infiltration in the tumor microenvironment. PLoS Biol 18(1): e30005915.Fallarino, F. et al. (2006) The combined effects of tryptophan starvation and tryptophan catabolites down-regulate T cell receptor æ-chain and induce a regulatory phenotype in naïve T cells. J Immunol 176:6752-6761 Citation Format: Hongmei He, Nam Hee Kim, Sangdon Han, Zhi Liang Chu. Evidence for a role of GPR35 in IDO1-mediated tumor immune escape by regulating Hippo-YAP pathway [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 LB426.

Dual molecule targeting HDAC6 leads to intratumoral CD4+ cytotoxic lymphocytes recruitment through MHC-II upregulation on lung cancer cells

BackgroundDespite the current therapeutic treatments including surgery, chemotherapy, radiotherapy and more recently immunotherapy, the mortality rate of lung cancer stays high. Regarding lung cancer, epigenetic modifications altering cell cycle, angiogenesis...

Abstract 2664: Targeting PD-L1/CMTM6 in myeloid cells results in elevated release of CCL2 to improve CD8 T cell-mediated antitumor response

Abstract Background: Although targeting myeloid cells has become one of the next generation targets for cancer immunotherapy, there is a lack of therapeutic tools to specifically target these cells. Our group has developed a novel humanized PD-L1-targeting antibody, H1A, that induces PD-L1 degradation via blockade of PD-L1 and CMTM6, therefore limiting PD-L1 intrinsic signaling while also preventing interactions with PD-1. In the immune cell compartment, CMTM6 expression is restricted to myeloid cells, making these cells the primary target of H1A. Recently, we unexpectedly found that targeting intrinsic PD-L1 in myeloid cells via H1A resulted in increased release of CCL2 from myeloid cells. In this study, we examined the role of CCL2/CCR2 signaling in CD8 T cell function using human peripheral blood-derived immune cells and evaluated the therapeutic potential of H1A antibody using our humanized PD-L1/PD-1 mouse model. Methods: Human PBMCs derived from healthy donors were treated with H1A or Atezolizumab, a blocking PD-L1 antibody, followed by mass cytometry and flow cytometry to evaluate immune cell phenotype and functional states. PD-L1 expressing myeloid cells isolated from human PBMCs were treated with H1A or Atezolizumab and assessed for CCL2 secretion using multiplex immunoassays. CCL2 production and transcription were confirmed by flow cytometry and single-cell RNA-sequencing. CCR2 blockade was used on human PBMCs to evaluate the effects of CCL2/CCR2 signaling on T cell function alongside H1A treatment. Finally, in vivo antitumor activity of H1A and Atezolizumab were compared in two humanized PD-L1 tumor models. Results: H1A reduced the frequency of regulatory T cells and increased effector T cells, in whole PBMCs upon global T cell activation with anti-CD3/CD28. H1A enhanced the secretion and production of CCL2 from myeloid cells, which was confirmed at a transcript level. CCR2 blockade diminished CD8 T cells’ ability to differentiate into effector cells in H1A treated PBMCs. H1A demonstrated comparable therapeutic effects with Atezolizumab in treatment of immunogenic and ICI-responsive mouse tumor MC38, which is CD8 T cell-dependent, but showed superior therapeutic effects in treatment of ICI-insensitive mouse tumor E0771 compared to Atezolizumab. Both treatments elicited durable memory specific immune responses upon E0771 tumor rechallenge. Conclusion: H1A demonstrated a superior antitumor activity compared to Atezolizumab in our preclinical models via a new mechanism by which H1A caused degradation of intrinsic PD-L1 in myeloid cells. This causes more release of CCL2 to improve T cell function via CCR2 upon T cell activation. Thus, H1A is emerging as a new immunotherapy tool to target PD-L1/CMTM6 in myeloid cells for treatment of cancers that are refractory to current immune checkpoint inhibitor therapy. Citation Format: Michelle Alexandria Hsu, Xin Liu, Ying Li, Whitney Barham, Kevin Pavelko, Jake Hirdler, Fabrice Lucien, Haidong Dong. Targeting PD-L1/CMTM6 in myeloid cells results in elevated release of CCL2 to improve CD8 T cell-mediated antitumor response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2664.

Abstract 6629: Cancer-associated nerves regulate anti-tumor immunity in pancreatic cancer

Abstract Nerves serve an emerging component of the tumor microenvironment (TME), contributing to tumorigenesis and cancer progression. Neural invasion (NI) is a common feature of pancreatic ductal adenocarcinoma (PDAC), accounting for distant metastasis and local recurrence. However, the mechanism by which tumor associated nerves (TANs) regulate anti-tumor immunity remains largely elusive. Here, we investigated the association between TANs and immunosuppressive TME to develop more effective therapeutic strategies for PDAC. Using tumor samples of PDAC patients, we identified that the nerves invaded by cancer cells showed increased adrenergic activation accompanied with no parasympathetic or sensory innervation changes. Patients with severe NI were associated with increased catecholamine levels. Additionally, single-cell RNA-sequencing and spatial transcriptome analysis of tumors from patients with PDAC revealed that peri-neural niches of severe NI patients were characterized by decreased CD8+ T cells and increased activity of M2 polarization of tumor-associated macrophages (TAMs), and regulatory T (Treg) cells, which was validated by multiplexed immunofluorescence staining. We further identified that CD8+ T cells expressing β-adrenaline receptors (β-ARs) reduced proliferation and cytokine production when exposure to catecholamines in a dose-dependent manner or co-cultured with dorsal root ganglia pretreated with cancer cells. KrasLSL-G12D; p53LoxP; Pdx1-CreER (KPC) mice treated with catecholamines accelerated tumor progression by inhibiting T cell-mediated antitumor responses, which was abrogated by surgical sympathectomy of KPC mice. Especially, in an orthotopic PDAC model, nonselective β-blocker propranolol in combination with immune checkpoint blockade (ICB) significantly enhanced active CD8+ T cells with concurrent reduced tumor growth. We suggest a novel regulatory mechanism of inhibiting anti-tumor immunity that can promote cancer progression mediated by TANs invasion. These data establish a close connection between the nerves, cancer cells, and immune cells and provide the potential novel targets of therapeutic approaches in PDAC. Citation Format: Ruiyuan Xu, Jianlu Song, Yuan Chen, Xinpeng Yin, Chengcheng Wang, Yupei Zhao. Cancer-associated nerves regulate anti-tumor immunity in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6629.

Abstract 4048: Comparative effects of SOS1 inhibitor with IL-6 blockade and their combination on Kras mutant lung cancer

Abstract Despite recent advances in treatment, lung adenocarcinoma (LUAD), particularly harboring Kras mutations, is still the leading cause of cancer mortality. We and others have previously shown that Kras mutant LUAD development and progression is associated with intrinsic inflammatory characteristics driven by epithelial NF-κB activation, increased levels of IL-6 (which is transcriptionally regulated by NF-κB), and activation of the IL-6-responsive transcription factor STAT3. We further demonstrated that IL-6 blockade suppresses lung tumorigenesis by reducing tumor-associated immunosuppressive myeloid populations and induction of a T cell-mediated anti-tumor response. The recent discovery of a novel SOS1-targeting compound (BI-3406) that selectively inhibits the KRAS-SOS1 interaction and leads to anti-proliferative activity has opened up the possibility to more efficiently inhibit Kras mutant lung cancer. Accordingly, in this study we used a mouse model of KRAS mutant LUAD (CC-LR) to compare the therapeutic effects of BI-3406, IL-6 blockade, and MEK inhibitor (trametinib). We also tested whether inhibiting IL-6 driven pro-tumor immune response would provide a synergistic/additive response and increase the tumor inhibitory effect of either BI-3406 or Trametinib. Eight cohorts of 14-week-old female mice were treated with either anti-IL-6 antibody, trametinib, or BI-3406, or their combinations for 4 weeks, and their tumor burden was compared at the end of study. We observed a significant reduction in tumor multiplicity and tumor area in response to all monotherapies, with the highest effect in the trametinib treated cohort. Neither combination therapy led to decreased tumor burden over either of the monotherapy regimens in our model. However, we observed an increase in T helper 1 and CD8 T expressing IFNγ cell populations in the cohort treated with Trametinib and anti-IL-6 Ab combination. In addition, using qPCR analysis of RNA extracted from the whole lung we found a higher expression of IFNγ along with a reduced expression of IL-10 in the cohort treated with BI-3406 and anti-IL-6 Ab combination. This suggests that these combinations may have the potential to improve the anti-tumor immune responses. Hence, we conclude that further adjustment of the treatment regimen (doses, interval, duration) may allow to obtain improved anti-tumor efficacy with these combinations. Overall, this study provides a new research perspective for the improvement of currently available treatment modalities for patients with Kras mutant lung cancer that could be further explored preclinically. Citation Format: Katherine E. Larsen, Maria J. Arredondo Sancristobal, Melody Zarghooni, Avantika Krishna, Maria T. Grimaldo, Nastaran Karimi, Arnav Gaitonde, Michael J. Clowers, Seyed Javad Moghaddam. Comparative effects of SOS1 inhibitor with IL-6 blockade and their combination on Kras mutant lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4048.

Abstract 33: Revitalizing CAR-T cells for TNBC: Targeting phosphorylation of TCF7 to overcome T cell exhaustion

Abstract Breast cancer stands as the second leading cause of cancer-related deaths among women in the United States, with triple-negative breast cancer (TNBC) representing the most aggressive subtype. Although immune checkpoint inhibitors (ICI) demonstrated durable response in some TNBC patients, the added benefit of current FDA-approved ICI in combination with chemotherapy is estimated to be only around 10%. Fortunately, TNBC displays the highest number of tumor-infiltrating lymphocytes (TILs), compared to other BC subtypes, indicating an optimal context for the survival of T cells. Therefore, CAR-T therapy emerges as a promising therapeutic option for TNBC patients. Expanding the application of CAR-T therapies to solid tumors, including breast cancer, remains challenging. One of the key hurdles lies in the immunosuppressive tumor microenvironment, where the T cell receptor experiences long-term exposure to tumor antigens, leading to T cell exhaustion. This state impedes the T cells' capacity to efficiently target and eliminate cancer cells. Identifying key regulatory mechanisms downstream of the T cell receptor holds the potential to revolutionize existing immunotherapeutic strategies. In our study, we discovered that the presence of the master transcriptional factor of T cell stemness, TCF1, in CD8+ T cells, is essential for controlling TNBC tumors. TCF1 undergoes phosphorylation by LCK, a crucial component of initiating T cell receptor signaling, upon T cell activation. We found this phosphorylation site is indispensable for TCF1's transcriptional activities, inhibiting the downstream program of T-cell persistence and causing T-cell exhaustion. Reversing this process, either through LCK inhibition or introducing a non-phosphorylated form of TCF1, results in a more sustained CAR-T cell-mediated anti-tumor response. Our findings reveal the significance of TCF1 post-translational modification in the development and longevity of stem-like CD8+ T cells, bridging the gap between TCR signaling and transcriptional and epigenetic programs of stem-like CD8+ T cells. This insight contributes to a potential cure for TNBC by maintaining T cell persistence. Citation Format: Zhou Jiang, Yu-Yi Chu, Heng-Huan Lee, Mien-Chie Hung, Liuqing Yang, Chunru Lin. Revitalizing CAR-T cells for TNBC: Targeting phosphorylation of TCF7 to overcome T cell exhaustion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 33.

Abstract 2831: Development and application of the NCG-hIL2 mouse model: A humanized platform for enhanced NK cell evaluation in ADCC efficacy testing

Abstract Natural Killer (NK) cells play a pivotal role in immune surveillance and antitumor responses, making them valuable targets in cancer immunotherapy. The assessment of therapeutic antibodies' efficacy, particularly in the context of Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), necessitates models that faithfully recapitulate human NK cell responses. Here, we introduce the NCG-hIL2 mouse model, designed to address these requirements and advance our understanding of NK cell development. The NCG-hIL2 mouse model was engineered to express human Interleukin-2 (IL2) cytokine, a critical factor in NK cell development and activation. This humanized platform allows for the robust reconstitution of human NK cells through the transplantation of peripheral blood mononuclear cells (PBMCs) or hematopoietic stem cells (HSCs). In this study, we validate the NCG-hIL2 model's exceptional capability in supporting the reconstitution of human NK cells, highlighting the indispensable role of IL2 in NK cell development. Moreover, we demonstrate its utility in the evaluation of therapeutic antibodies, specifically Trastuzumab and the ADCC-enhanced Margetuximab, in the context of ADCC efficacy testing. Our findings reveal that the NCG-hIL2 model provides a unique advantage for assessing the impact of IL2 on NK cell development, thus facilitating a deeper understanding of the complex interplay between NK cells and therapeutic antibodies. The NCG-hIL2 mouse model serves as a valuable tool for studying NK cell development and evaluating the efficacy of immunotherapies, particularly in ADCC. By reconstituting human NK cells and leveraging the role of IL2, this model offers an enhanced platform for preclinical evaluation of therapeutic antibodies, ultimately advancing our ability to harness NK cell-mediated antitumor responses. It is poised to contribute significantly to the field of cancer immunotherapy and drug development. Citation Format: Yuan Fang, Hongyan Sun, Huiyi Wang, Jun Xing, Jialu Fan, Jing Zhao, Xiang Gao, Cunxiang Ju. Development and application of the NCG-hIL2 mouse model: A humanized platform for enhanced NK cell evaluation in ADCC efficacy testing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2831.

Abstract 3999: Augmentation of antitumor effects by CAR-T cells secreting anti-PD-1 single-chain antibody fused with IL-21

Abstract Background: Chimeric antigen receptor (CAR) T cell therapy has shown remarkable responses in hematologic malignancies. However, many patients suffer from limited response and tumor relapse due to lack of persisting CAR-T cells and immune escape. Delivery of immunomodulatory cytokines is one of the strategies to improve immune function; however, the systemic effect of cytokines can be detrimental. Methods: To prevent the toxic effects of cytokines, we proposed the concept of targeting cytokines to tumor-specific T cells in vivo. To this end, we developed CAR-T cells secreting a fusion protein (PD-1Ab21) composed of anti-PD-1 single chain antibody and IL-21, which target IL-21 to CAR-T cells to promote their proliferation and differentiation into memory cells while blocking the PD-1 signal of CAR-T cells. The secretion and functions of PD-1Ab21 were identified. The proliferation and differentiation of CAR-T cells secreting PD-1Ab21 (PD-1Ab21-CAR-T) were compared in vitro with that of the conventional CAR-T cells. The therapeutic effects of CAR-T cells secreting PD-1Ab21 were studied in immunodeficient mice engrafted with human Burkitt lymphoma Daudi, multiple myeloma cell U266 and Her2/neu+ breast cancer cell BT474. Results: The results showed that the culture supernatant of PD-1Ab21-CAR-T cells, like anti-PD-1 antibody, blocked the binding of PD-1 to PD-L1 and stimulated STAT3 phosphorylation in human T lymphocytic leukemia cell Hut78 with the same activity as IL-21. In the conventional culture milieu with high dose of IL-2, the proliferation of the PD-1Ab21-CAR-T cells was not different from that of conventional CAR-T cells. While cultured with low dose of IL-2 that could not support the proliferation of conventional CAR-T cells, the PD-1Ab21-CAR-T cells still showed significant proliferation. A major fraction of the PD-1Ab21-CAR-T products was shown to co-express CCR7, CD62L and CD45RA, and express high level of TCF-1, indicating a memory stem-like phenotype. While the most of conventional CAR-T cells showed effector phenotype defined as CD45RA+CCR7-. Furthermore, adoptive transfer of PD-1Ab21-CAR-T cells exhibited significantly improved CAR-T cell expansion and resulted in superior tumor eradication in the xenograft models of human B-cell malignancy, multiple myeloma and Her2/neu+ breast cancer. The enhanced cellular function by secreting PD-1Ab21 was mediated through an autocrine and/or paracrine manners. Conclusion: We developed an enhanced CAR-T cells. Our data provide preclinical evidence to support the translation of this design for an improved CAR-T cell-mediated anti-tumor response. Citation Format: Ying Li, Jitao Zhao, Xiangrui Cheng, Hang Li, Ran Tian, Qianqian He, Shengdian Wang. Augmentation of antitumor effects by CAR-T cells secreting anti-PD-1 single-chain antibody fused with IL-21 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3999.

Drug-Loaded Tumor-Derived Microparticles Elicit CD8+ T Cell-Mediated Anti-Tumor Response in Hepatocellular Carcinoma.

Hepatocellular Carcinoma (HCC) poses significant challenges due to limited effective treatments and high recurrence rates. Immunotherapy, a promising approach, faces obstacles in HCC patients due to T-cell exhaustion and immunosuppression within the tumor microenvironment. Using doxorubicin-loaded tumor-derived microparticles (Dox-TMPs), the mice with H22 ascites model and subcutaneous tumors model were treated. Following the treatment, mice were re-challenged with H22 cells to compare the therapeutic effects and recurrence among different groups of mice, alongside examining the changes in the proportions of immune cells within the tumor microenvironment. Furthermore, Dox-TMPs were combined with anti-PD-1 to further validate their anti-tumor efficacy. In vitro studies using various liver cancer cell lines were conducted to verify the tumor-killing effects of Dox-TMPs. Additionally, CD8+ T cells from the abdominal cavity of tumor-free mice were co-cultured with H22 cells to confirm their specific tumor-killing abilities. Dox-TMPs demonstrate effective anti-tumor effects both in vitro and in vivo. In vivo, their effectiveness primarily involves enhancing CD8+ T cell infiltration, alleviating T cell immunosuppression, and improving the immune microenvironment to combat tumors. When used in combination with anti-PD-1, their anti-tumor effects are further enhanced. Moreover, some mice treated with Dox-TMPs developed anti-tumor immunity, displaying a self-specific T-cell immune response upon re-challenged with tumor cells. This suggests that Dox-TMPs also have the potential to act as a long-term immune response against tumor recurrence, indicating their capability as a tumor vaccine. Dox-TMPs exhibit a dual role in liver cancer by regulating T cells within the tumor microenvironment, functioning both as an anti-tumor agent and a potential tumor vaccine.

Therapeutic restoration of miR-126-3p as a multi-targeted strategy to modulate the liver tumor microenvironment.

Impaired natural killer (NK) cell-mediated antitumor responses contribute to the growth of liver tumors. Expression of a disintegrin and metalloprotease 9 (ADAM9) increases shedding of membrane-bound major histocompatibility complex class I chain-related protein A and results in evasion from NK cell-mediated cytolysis. ADAM9 is also involved in angiogenesis and tumor progression and is a target of miR-126-3p, a tumor suppressor that is downregulated and alters tumor cell behavior in the liver and other cancers. We evaluated the restoration of miR-126-3p and modulation of the miR-126-3p/ADAM9 axis as a therapeutic approach to simultaneously enhance NK cell-mediated cytolysis while targeting both tumor cells and their microenvironment. Precursor miRNAs were loaded into milk-derived nanovesicles to generate therapeutic vesicles (therapeutic milk-derived nanovesicles) for the restoration of functional miR-126-3p in recipient cancer cells. Administration of therapeutic milk-derived nanovesicles increased miR-126-3p expression and reduced ADAM9 expression in target cells and was associated with an increase in membrane-bound major histocompatibility complex class I chain-related protein A. This enhanced NK cell cytolysis in adherent tumor cells and in multicellular tumor spheroids while also impairing angiogenesis and modulating macrophage chemotaxis. Moreover, IV administration of therapeutic milk-derived nanovesicles with adoptive transfer of NK cells reduced tumor burden in orthotopic hepatocellular cancer xenografts in mice. A directed RNA therapeutic approach can mitigate NK cell immune evasion, reduce angiogenesis, and alter the tumor cell phenotype through the restoration of miR-126-3p in liver tumor cells. The pleiotropic effects elicited by this multi-targeted approach to modulate the local tumor microenvironment support its use for the treatment of liver cancer.

Combined therapy of CAR-IL-15/IL-15Rα-T cells and GLIPR1 knockdown in cancer cells enhanced anti-tumor effect against gastric cancer

BackgroundChimeric antigen receptor (CAR) T cell therapy has shown remarkable responses in hematological malignancies with several approved products, but not in solid tumors. Patients suffer from limited response and tumor relapse due to low efficacy of CAR-T cells in the complicated and immunosuppressive tumor microenvironment. This clinical challenge has called for better CAR designs and combined strategies to improve CAR-T cell therapy against tumor changes.MethodsIn this study, IL-15/IL-15Rα was inserted into the extracellular region of CAR targeting mesothelin. In-vitro cytotoxicity and cytokine production were detected by bioluminescence-based killing and ELISA respectively. In-vivo xenograft mice model was used to evaluate the anti-tumor effect of CAR-T cells. RNA-sequencing and online database analysis were used to identify new targets in residual gastric cancer cells after cytotoxicity assay. CAR-T cell functions were detected in vitro and in vivo after GLI Pathogenesis Related 1 (GLIPR1) knockdown in gastric cancer cells. Cell proliferation and migration of gastric cancer cells were detected by CCK-8 and scratch assay respectively after GLIPR1 were overexpressed or down-regulated.ResultsCAR-T cells constructed with IL-15/IL-15Rα (CAR-ss-T) showed significantly improved CAR-T cell expansion, cytokine production and cytotoxicity, and resulted in superior tumor control compared to conventional CAR-T cells in gastric cancer. GLIPR1 was up-regulated after CAR-T treatment and survival was decreased in gastric cancer patients with high GLIPR1 expression. Overexpression of GLIPR1 inhibited cytotoxicity of conventional CAR-T but not CAR-ss-T cells. CAR-T treatment combined with GLIPR1 knockdown increased anti-tumor efficacy in vitro and in vivo.ConclusionsOur data demonstrated for the first time that this CAR structure design combined with GLIPR1 knockdown in gastric cancer improved CAR-T cell-mediated anti-tumor response.

MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32β–major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients’ skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

Bioresponsive and immunotherapeutic nanomaterials to remodel tumor microenvironment for enhanced immune checkpoint blockade

Immune checkpoint blockade (ICB) therapy is a revolutionary approach to treat cancers, but still have limited clinical applications. Accumulating evidence pinpoints the immunosuppressive characteristics of the tumor microenvironment (TME) as one major obstacle. The TME, characterized by acidity, hypoxia and elevated ROS levels, exerts its detrimental effects on infiltrating anti-tumor immune cells. Here, we developed a TME-responsive and immunotherapeutic catalase-loaded calcium carbonate nanoparticles (termed as CAT@CaCO3 NPs) as the simple yet versatile multi-modulator for TME remodeling. CaCO3 NPs can consume protons in the acidic TME to normalize the TME pH. CAT catalyzed the decomposition of ROS and thus generated O2. The released Ca2+ led to Ca2+ overload in the tumor cells which then triggered the release of damage-associated molecular patterns (DAMP) signals to initiate anti-tumor immune responses, including tumor antigen presentation by dendritic cells. Meanwhile, CAT@CaCO3 NPs-induced immunosupportive TME also promoted the polarization of the M2 tumor-associated macrophages to the M1 phenotype, further enhancing tumor antigen presentation. Consequently, T cell-mediated anti-tumor responses were activated, the efficacy of which was further boosted by aPD-1 immune checkpoint blockade. Our study demonstrated that local treatment of CAT@CaCO3 NPs and aPD-1 combination can effectively evoke local and systemic anti-tumor immune responses, inhibiting the growth of treated tumors and distant diseases.

Thymoquinone Treatment Enhances T Cell-Mediated Anti-Tumor Response In Vitro

Oil from Nigella sativa seeds (“black seed oil”) has been used for health care and medical purposes for over 2000 years. The major active compound thymoquinone (TQ) has been shown to have immune regulatory effects in various diseases. Tumor microenvironment is critical for tumor development. Immune cells, particularly T cells, are central players to kill tumor cells and affect tumor progression and metastasis. The impact of TQ on human T cell-mediated anti-tumor response was investigated. Using human PBMCs, we activated T cells with anti-CD3/CD28 in vitro, and treated cells with TQ. First, we tested the impact of TQ on T cell activation, proliferation and apoptosis; second, the anti-tumor effect of T cells after treatment with TQ; last, we determined alterations in T cells gene expression at the RNA level after TQ treatment. TQ treatment increased activation and proliferation of T cells at days 2-4 and more activation-induced cell death at day 3. After 7-11 days, TQ-treated cells showed less survival than cells treated with control medium. At low TQ concentration (10uM), treatment induced more CD3+ T cell proliferation; while at 20uM and 50uM TQ showed more cytotoxic effect to T cells, and more cell death. When co-cultured with multiple types of cancer cells, TQ-treated T cells exhibited significantly enhanced anti-tumor activity, indicated by more tumor cell apoptosis and less cell expansion. Gene expression study showed upregulation of NFAT signaling pathway, including 10+ fold up-regulation of IL-2, which might explain the enhanced anti-tumor effect after TQ treatment. In summary, TQ treatment can enhance human T cell-mediated anti-tumor effect in vitro. This immunoregulatory function of black seed oil could potentially benefit patients of different cancer types.

CCDC134 facilitates T cell activation through the regulation of early T cell receptor signaling.

Modulation of surface T cell antigen receptor (TCR) expression is crucial for proper T cell development and maintenance of mature T cell function at steady state and upon stimulation. We previously determined that CCDC134 (coiled-coil domain containing 134), a cytokine-like molecule that served as a potential member of the γc cytokine family, contributes to antitumor responses by augmenting CD8+ T cell-mediated immunity. Here we show that T cell-specific deletion of Ccdc134 decreased peripheral mature CD4+ and CD8+ T cells, which resulted in impaired T cell homeostasis. Moreover, Ccdc134-deficient T cells exhibited an attenuated response to TCR stimulation in vitro, showing lower activation and proliferative capacity. This was further reflected in vivo, rendering mice refractory to T cell-mediated inflammatory and antitumor responses. More importantly, CCDC134 is associated with TCR signaling components, including CD3ϵ, and attenuated TCR signaling in Ccdc134-deficient T cells via altered CD3ϵ ubiquitination and degradation. Taken together, these findings suggest a role for CCDC134 as a positive regulator of TCR-proximal signaling and provide insight into the cell-intrinsic functional consequences of Ccdc134 deficiency in the attenuation of T cell-mediated inflammatory and antitumor responses.