Murine Tumor Models Research Articles

Oxygen Self-Supplied Perfluorocarbon-Modified Micelles for Enhanced Cancer Photodynamic Therapy and Ferroptosis.

Photodynamic therapy (PDT) and ferroptosis show significant potential in tumor treatment. However, their therapeutic efficacy is often hindered by the oxygen-deficient tumor microenvironment and the challenges associated with efficient intracellular drug delivery into tumor cells. Toward this end, this work synthesized perfluorocarbon (PFC)-modified Pluronic F127 (PFC-F127), and then exploits it as a carrier for codelivery of photosensitizer Chlorin e6 (Ce6) and the ferroptosis promoter sorafenib (Sor), yielding an oxygen self-supplying nanoplatform denoted as Ce6-Sor@PFC-F127. The PFCs on the surface of the micelle play a crucial role in efficiently solubilizing and delivering oxygen as well as increasing the hydrophobicity of the micelle surface, giving rise to enhanced endocytosis by cancer cells. The incorporation of an oxygen-carrying moiety into the micelles enhances the therapeutic impact of PDT and ferroptosis, leading to amplified endocytosis and cytotoxicity of tumor cells. Hypotonic saline technology was developed to enhance the cargo encapsulation efficiency. Notably, in a murine tumor model, Ce6-Sor@PFC-F127 effectively inhibited tumor growth through the combined use of oxygen-enhanced PDT and ferroptosis. Taken together, this work underscores the promising potential of Ce6-Sor@PFC-F127 as a multifunctional therapeutic nanoplatform for the codelivery of multiple cargos such as oxygen, photosensitizers, and ferroptosis inducers.

Elucidation of Spatial Cooperativity in Chemo-Immunotherapy by a Sequential Dual-pH-Responsive Drug Delivery System.

Combining immune checkpoint blockade with chemotherapy through nanotechnology is promising in terms of safety and efficacy. However, the distinct subcellular distribution of each ingredient's action site makes it challenging to acquire an optimal synergism. Herein, a dual-pH responsive hybrid polymeric micelle system, HNP(αPDL16.9, Dox5.3), is constructed as a proof-of-concept for the spatial cooperativity in chemo-immunotherapy. HNP retains the inherent pH-transition of each polymer, with stepwise disassembly under discrete pH thresholds. Within weakly acidic extracellular tumor environment, αPDL1 is first released to block the checkpoint on cell membranes. The remaining intact Doxorubicin-loaded micelle NP(Dox)5.3 displays significant tropism toward tumor cells and releases Dox upon lysosomal pH for efficient tumor immunogenic cell death without immune toxicity. This sequential-released pattern boosts DC activation and primes CD8+ T cells, leading to enhanced therapeutic performance than single agent or an inverse-ordered combination in multiple murine tumor models. Using HNP, the indispensable role of conventional type 1 DC (cDC1) is identified in chemo-immunotherapy. A co-signature of cDC1 and CD8 correlates with cancer patient survival after neoadjuvant Pembrolizumab plus chemotherapy in clinic. This study highlights spatial cooperativity of chemo- and immuno-agents in immunoregulation and provides insights into the rational design of drug combination for future nanotherapeutics development.

CD200 is overexpressed in the pancreatic tumor microenvironment and predictive of overall survival

Pancreatic cancer is an aggressive disease with a 5 year survival rate of 13%. This poor survival is attributed, in part, to limited and ineffective treatments for patients with metastatic disease, highlighting a need to identify molecular drivers of pancreatic cancer to target for more effective treatment. CD200 is a glycoprotein that interacts with the receptor CD200R and elicits an immunosuppressive response. Overexpression of CD200 has been associated with differential outcomes, depending on the tumor type. In the context of pancreatic cancer, we have previously reported that CD200 is expressed in the pancreatic tumor microenvironment (TME), and that targeting CD200 in murine tumor models reduces tumor burden. We hypothesized that CD200 is overexpressed on tumor and stromal populations in the pancreatic TME and that circulating levels of soluble CD200 (sCD200) have prognostic value for overall survival. We discovered that CD200 was overexpressed on immune, stromal, and tumor populations in the pancreatic TME. Particularly, single-cell RNA-sequencing indicated that CD200 was upregulated on inflammatory cancer-associated fibroblasts. Cytometry by time of flight analysis of PBMCs indicated that CD200 was overexpressed on innate immune populations, including monocytes, dendritic cells, and monocytic myeloid-derived suppressor cells. High sCD200 levels in plasma correlated with significantly worse overall and progression-free survival. Additionally, sCD200 correlated with the ratio of circulating matrix metalloproteinase (MMP) 3: tissue inhibitor of metalloproteinase (TIMP) 3 and MMP11/TIMP3. This study highlights the importance of CD200 expression in pancreatic cancer and provides the rationale for designing novel therapeutic strategies that target this protein.

Linagliptin decreased the tumor progression on glioblastoma model

PurposeDipeptidyl peptidase-4 (DPP-4) inhibitors are oral hypoglycemic drugs and are used for type II diabetes. Previous studies showed that DPP-4 expression is observed in several tumor types and DPP-4 inhibitors suppress the tumor progression on murine tumor models. In this study, we evaluated the role of DPP-4 and the antitumor effect of a DPP-4 inhibitor, linagliptin, on glioblastoma (GBM). MethodsWe analyzed DPP-4 expression in glioma patients by the public database. We also analyzed DPP-4 expression in GBM cells and the murine GBM model. Then, we evaluated the cell viability, cell proliferation, cell migration, and expression of some proteins on GBM cells with linagliptin. Furthermore, we evaluated the antitumor effect of linagliptin in the murine GBM model. ResultsThe upregulation of DPP-4 expression were observed in human GBM tissue and murine GBM model. In addition, DPP-4 expression levels were found to positively correlate with the grade of glioma patients. Linagliptin suppressed cell viability, cell proliferation, and cell migration in GBM cells. Linagliptin changed the expression of phosphorylated NF-kB, cell cycle, and cell adhesion-related proteins. Furthermore, oral administration of linagliptin decreases the tumor progression in the murine GBM model. ConclusionInhibition of DPP-4 by linagliptin showed the antitumor effect on GBM cells and the murine GBM model. The antitumor effects of linagliptin is suggested to be based on the changes in the expression of several proteins related to cell cycle and cell adhesion via the regulation of phosphorylated NF-kB. This study suggested that DPP-4 inhibitors could be a new therapeutic strategy for GBM.

Abstract LB117: Virus-inspired Particles (ViPs) harnessing cytomegalovirus immune memory for local and systemic cancer immunotherapy

Abstract VerImmune is pioneering a First-in-Class treatment known as “Anti-tumor Immune Redirection” (AIR). This approach repurposes a patient’s pre-existing anti-viral or childhood vaccine immunity towards tumor cells for targeted destruction. VerImmune’s lead product, VERI-101, leverages pre-existing CD8+ T-cell immune memory acquired from past human cytomegalovirus (HCMV) infections. VERI-101 consists of VerImmune’s proprietary platform technology known as ViPs (Virus-inspired Particles) that are conjugated on their surface with a CD8+ T cell viral peptide antigen. ViPs are based on a modified mouse papillomavirus capsid protein of which 60 copies self-assemble into a 20-30nm T=1 icosahedral structure. In the case of VERI-101, the ViP is conjugated with an HLA-A*0201 restricted peptide epitope (NLVPMVATV, [NLV]), derived from the CMV pp65 antigen with an upstream furin protease cleavage site. The mechanism of action of AIR-ViPs including VERI-101 has been previously presented and involves three steps. Briefly, (1) VERI-101 targets the surface of the tumor cells and (2) enables the presentation of the CMV viral epitopes on their surface MHC, together (3) stimulating a recall of the pre-existing CMV memory response to attack the cancer cells (Dorrier et al., 2023 AACR). Here, we sought to study the in vivo anti-tumor efficacy of AIR-ViPs via both intra-tumoral and systemic treatment routes in two murine tumor models with pre-existing murine CMV (MCMV) immunity: (1) MC38 subcutaneous tumors for local and (2) B16.F10 lung metastasis for systemic treatments. As human CMV is species-specific, instead of VERI-101, a surrogate product, VERI-003 which redirects MCMV immunity, was tested as a single agent or in combination with anti-PD-1 in these tumor models. Our intra-tumoral studies with VERI-003 alone showed a dose-dependent anti-tumor effect (from 5 to 100ug) compared to no treatment controls. Surprisingly, no dose dependence was observed across the same three dose levels when combined with anti-PD-1, although significantly better anti-tumor effects occurred leading to complete tumor clearances in 50% of mice. Statistically significant prolonged survival was observed in most treated groups compared to controls. Our systemic studies with VERI-003 were consistent with our intratumoral studies in showing statistically significant single agent anti-tumor efficacy against B16.F10 lung metastases compared to no treatment. Anti-tumor effects of anti-PD-1 and combination were also observed. Additional studies are on-going to assess dose dependence and analysis of PK/PD effects. Taken together, our initial in vivo results demonstrate the tumor antigen-agnostic therapeutic potential of AIR and our AIR-ViP technology as a novel class of immuno-therapeutic drugs that could be used either as a monotherapy or in combination with checkpoint inhibitors. Citation Format: Cayce Dorrier, Felagot Abebe, Olivia Pak, Emily De-Bodene, Joshua Wang. Virus-inspired Particles (ViPs) harnessing cytomegalovirus immune memory for local and systemic cancer immunotherapy [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 LB117.

Abstract LB075: Small molecule procaspase activating compound 1 (PAC-1) enhances CAR-T immunotherapy for solid tumors in syngeneic murine models

Abstract Chimeric antigen receptor (CAR)-T cell therapy has been shown to effectively treat solid tumors in syngeneic murine models, but antigen loss and T cell trafficking into the tumors pose major obstacles to its long-term efficacy. Here we explored a combination therapy against advanced stages of colorectal and ovarian syngeneic murine tumor models using a tumor-specific small molecule (PAC-1) that triggers the engagement of the host immune system and synergizes with a Tn-specific adoptively transferred 237 CAR-T immunotherapy. PAC-1 has been shown to induce apoptosis in tumor cells with high expression of procaspase 3, via chelation of inhibitory zinc and release of active executioner caspase 3. PAC-1 also recently completed a phase I trial (NCT02355535) and was shown to be well-tolerated in late-stage cancer patients. RNA sequencing of CT26 colorectal cells stimulated with PAC-1 for 24 hours revealed that PAC-1 induced global changes at the transcriptome level, up-regulating genes involved in immune activation and apoptosis, and down-regulating genes involved in DNA repair, cell cycle regulation, and myc-driven proliferation. Validation of RNAseq data was performed using a combination of RT-qPCR, Western blot, flow cytometry, and co-culture studies. A combination of transcriptome and exome sequencing analyses in murine colorectal cell line CT26 revealed that the PAC-1-mediated down-regulation of DNA repair machinery led to somatic alterations in the genome and a higher mutational load in tumor cells, subsequently presented as neo-antigens by antigen-presenting cells. As a result, host CD8+ cytotoxic T cells were able to infiltrate tumors and reduce the tumor burden. Tn-dependent CARs have been used recently to demonstrate the proof of concept in the targeting of cancer-specific Tn-antigens such as the Tn-MUC1 antigen in humans, and an analogous Tn-OTS8 target in mice. In our murine ID8 ovarian tumor model, untreated mice with disseminated tumors have a median survival of 71 days. As a single agent administered intraperitoneally, PAC-1 extended the median survival to 90 days (p<0.0001), while 237 CAR-T treated mice have a median survival of 103 days (p<0.0001). A combination of the two treatment modalities (PAC-1 administered before 237 CAR-T) further extended the median survival to 145 days (p=0.048). Administering PAC-1 after 237 CAR-T also modestly extended the median survival to 132 days (p=0.06). Taken altogether, our results demonstrate that PAC-1 engages the immune system to treat cancer by inducing expression of pro-inflammatory cytokines in tumor cells allowing the recruitment of CD8+ effector T cells to the tumor microenvironment. Combination strategies that boost T cell trafficking shows great promise to enhance the anti-tumor efficacy and feasibility of adoptive CAR-T therapy against solid tumors. Citation Format: Diana R. Ranoa, Yifei Kang, Jenny Drnevich, Gloria Rendon, Christopher J. Fields, Keith Bailey, Edward J. Roy, Timothy M. Fan, David M. Kranz, Paul J. Hergenrother. Small molecule procaspase activating compound 1 (PAC-1) enhances CAR-T immunotherapy for solid tumors in syngeneic murine models [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 LB075.

Abstract LB118: HM16390, a novel long-acting IL-2 analog with fine-tuned binding affinities to IL-2 receptor subunits for favorable safety profile, exhibits potent tumor killing effect in the various tumor syngeneic models

Abstract Although recombinant human IL-2 (rhIL-2, aldesleukin) produced approximately a 15% objective response rate in patients with renal cell carcinoma (RCC) and metastatic melanoma, its IL-2Rα (CD25)-biased binding and short half-life (t1/2 in human: 13-85 min) require a high dose and frequent dosing interval, leading to systemic toxicity such as vascular leak syndrome (VLS) and cytokine release syndrome (CRS). To overcome this limitation, various research groups are developing engineered IL-2 muteins with abolished CD25 binding affinity. While such IL-2 muteins may reduce CD25-mediated toxicity, there is a risk of a lopsided immune response. Furthermore, concomitantly reduced affinity to IL-2Rβ (CD122) may cause insufficient anti-tumor activity. We are developing HM16390, a long-acting IL-2 analog with a significantly increased binding affinity to CD122 for potent tumor killing effect. Simultaneously, optimal binding property to CD25 was introduced for a suppression of uncontrolled systemic immune response via peripheral Treg expansion. From these novel sequence modifications, HM16390 exhibited approximately 14-fold potent activity in human NK and CD8+ T cells compared to rhIL-2 and comparable activity with rhIL-2 in human Tregs (EC50 of STAT5 phosphorylation) without undesired release of cytokines associated with CRS. In B16F10 mouse model, HM16390 has a longer-lasting PK property (t1/2: 14.2~26.0 hr) after single subcutaneous (SC) administration. CD8+ T cells were significantly increased in peripheral blood along with a transient increase of peripheral Tregs, suggesting that HM16390 not only has a significant effect on expansion of CD8+ T cells but can simultaneously modulate exaggerated peripheral immune response. It is also noteworthy that, unlike in the peripheral, Tregs were drastically reduced in the tumor immune microenvironment, and CD8+ T cells were significantly increased. Next, in orthotopic model of mouse RCC (RENCA-luc cell implantation), across treatment groups, 40%(n=4/10) to 80%(n=8/10) of animals achieved complete tumor regression in dose-dependent manner after once weekly SC injection of HM16390 for 4 weeks. Furthermore, tumor nodules were not observed in lung and kidney after intravenous (IV) rechallenge of RENCA cells in the mice cured by HM16390 for at least 4 months after drug discontinuation. This indicates a long-term immunological memory response of generated memory cells by treatment of HM16390. In conclusion, HM16390 demonstrates potent and durable anti-tumor activity in various murine tumor models via its enhanced CD122 binding affinity, and incorporated optimal CD25 binding affinity may alleviate systemic toxicity by immunomodulatory role of peripheral Tregs. Citation Format: Sol-Bi Shin, Jinyoung Kim, Jaehyuk Choi, Seongju Jeong, Yunjae Kim, Jooyun Byun, Sungmin Bae, Daejin Kim, In Young Choi. HM16390, a novel long-acting IL-2 analog with fine-tuned binding affinities to IL-2 receptor subunits for favorable safety profile, exhibits potent tumor killing effect in the various tumor syngeneic models [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 LB118.

Abstract LB123: Conditionally active, therapeutic lymphotoxin beta receptor (LTBR) agonist bispecific antibodies for induction of tertiary lymphoid structures in the treatment of solid tumors

Abstract The presence of tertiary lymphoid structures (TLS) and associated high endothelial venules (HEV) in the tumor microenvironment strongly correlates with improved prognosis and treatment outcomes across a wide range of solid tumors. These clinical observations, now replicated repeatedly, highlight the therapeutic potential of induction of TLS and/or boosting TLS functions, which include acting as a point of entry and education for immune effector cells locally in the tumor. Lymphotoxin beta receptor (LTBR) signalling is essential for lymphoid structure development and the ectopic expression of its ligands, lymphotoxin αβ and LIGHT, is sufficient for TLS formation in vivo but challenging for therapeutic development. Here we present human bispecific antibodies (bsAbs) which conditionally agonize LTBR on co-engagement of fibroblast activation protein (FAP), a tumor microenvironment specific marker expressed by cancer associated fibroblasts. In vitro characterisation of these therapeutic bsAbs is presented, along with in vivo preclinical evaluation of surrogate bsAbs binding to mouse LTBR and mouse FAP in murine tumor models. Results - Therapeutic bsAbs were identified following an extensive screening campaign combining LTBR and FAP binding arms on an engineered human Fc with minimal FcyR binding. In vitro assays using primary cancer associated fibroblasts and LTBR positive cells demonstrated conditionally active therapeutic bsAbs potently activated LTBR in the presence of FAP expressing cells, whereas in the absence of FAP expressing cells no activity was observed. Surrogate bsAbs demonstrated monotherapy activity and led to tumor regressions in combination with anti-PDL1 therapy in an EMT6 mouse model, a syngeneic orthotopic model of breast cancer. Flow cytometry of endpoint tumors showed robust formation of HEVs and increased infiltration of T cells and B cells. In addition, we demonstrate that LTBR agonism, but not PD-L1 inhibition, leads to the formation of TLS structures containing organized lymphocyte aggregates with the appearance of germinal centres and accumulations of T and B cells in a mouse model of lung cancer. In conclusion, conditionally active FAP-LTBR bispecifics activate LTBR in the tumor microenvironment and induce HEV and TLS formation, leading to potent monotherapy activity in vivo, and to tumor regression in combination with PD-L1. These data support the development of FAP-LTBR bispecifics for the treatment of solid tumors as monotherapy and in combination with standard of care. Citation Format: Marta Lewandowska, Fevzi Demircioglu, Lucy Penfold, Rebecca B. Riddle, Sameer Sirohi, Floriane Laurent, Richard Brown, Sonia Bains, Dara Bevan, Emma Stanley, Jeanine Pignatelli, James W. Legg, Ray Jupp. Conditionally active, therapeutic lymphotoxin beta receptor (LTBR) agonist bispecific antibodies for induction of tertiary lymphoid structures in the treatment of solid tumors [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 LB123.

Abstract CT258: Phase II trial of fecal microbiota transplantation in combination with ipilimumab and nivolumab in patients with advanced cutaneous melanoma (FMT-LUMINate trial)

Abstract Background: Several trials combining microbiome-based interventions with immune checkpoints inhibitors (ICI) are currently underway. Previous studies showed the potential of fecal microbiota transplant (FMT) to circumvent secondary anti-PD-1 resistance or improve first-line anti-PD-1 response in patients with advanced melanoma. Whether FMT can be used safely in combination with anti-PD-1/anti-CTLA-4 (dual ICI) and its impact on the microbiome composition remain unknown. Here, we report results from combining FMT with dual ICI in previously untreated patients (pts) with advanced melanoma (NCT04951583). Methods: 20 pts with previously untreated advanced melanoma were included. FMT from healthy donors was administered in oral capsules after bowel preparation 1 week prior to start of dual ICI. A total of 6 different donors were used. The primary endpoint was safety. Secondary endpoints included objective response rate (ORR) and microbiome shift using shotgun metagenomic sequencing. Longitudinal serum Il1rl1 gene product (sST2) epithelial integrity marker was measured. Stool from pts before and after FMT were transplanted into avatar mice (MCA-205 or B16 OVA) and then treated with dual ICI. Results: In the 20 pts enrolled, 13 (65%) were male and median age was 56. Median follow-up was 6 months (range (IQR) 3.23; 12.33). FMT alone resulted in grade 1 toxicities. Grade 1-2 immune related adverse event (irAE) occurred in 80% of pts and 65% developed grade >3 irAE. Diarrhea or colitis was the most frequent grade 3 irAE occurring in 4 (20%). 2 pts developed myocarditis (grade 3 and grade 4, respectively). 6 (30%) pts completed all 4 cycles of dual ICI. 6 (43%) pts that developed irAE grade 3 received FMT from the same donor. ORR was 70% (2 complete responses (CR) and 12 partial responses (PR)). Two pts died; one from unknown cause in PR and one from disease progression. Microbiome profiling beta-diversity analyses revealed separate clustering of responders (R) and non-responders (NR) post-FMT (p=0.024). We observed an enrichment of Prevotella copri, Ruminoccocaceae and Eubacterium in R pts post-FMT. Pts who developed colitis were found to have a higher level of sST2 in plasma 1 week after FMT in comparison to those who did not develop colitis (p<0.05). In both avatar murine tumor models, microbiome composition with R pts’ feces (without ICI) 1 month post-FMT had reduced tumor growth compared to those treated with respective NR pt feces. Additionally, dual ICI led to significantly improved tumor control in mice treated with R pts’ feces post-FMT(p<0.005). Conclusions: The addition of FMT to dual ICI resulted in significant irAEs that occurred earlier, although the proportion was similar to previously described literature, with encouraging ORR. Metagenomic analysis depicted differences in the microbiome profiles of R compared to NR pts post FMT. These results support the study of FMT and immunotherapy in the randomized setting. Citation Format: Sreya Duttagupta, Meriem Messaoudene, Rahima Jamal, Catalin Mihalcioiu, Karl Belanger, John Lenehan, Wiam Belkaid, Seema Nair Parvathy, Jade Maillou, Yongjia Hu, Mayra Ponce, Taiki Hakozaki, Eder Mendez Salazar, Michael Silverman, Saman Maleki Vareki, Arielle Elkrief, Bertrand Routy. Phase II trial of fecal microbiota transplantation in combination with ipilimumab and nivolumab in patients with advanced cutaneous melanoma (FMT-LUMINate trial) [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 CT258.

Abstract LB218: Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids

Abstract In response to the high failure rate of new drugs in clinical trials, we have developed an innovative organotypic tumor spheroids platform, designed to mitigate the risks associated with advancing drugs to clinical stages. Utilizing patient-derived organotypic tumor spheroids (PDOTS), this platform uniquely captures both the phenotype and genotype of individual patient tumor microenvironments. This approach not only enhances the precision of preclinical models but also bridges the gap between laboratory research and clinical applicability. In this study, we assess the effectiveness of the first-in-class monoclonal antibody NMC-521 (NomoCan Pharmaceuticals, NY) using our ex vivo platform. Targeting the novel cancer-specific antigen NMC-1, NMC-521 exhibited significant growth inhibition of CT-26 tumors in syngeneic BALB/c mice, reducing tumor size by approximately 55% compared to the control. Similarly, in ex vivo settings with freshly excised CT-26 tumors (n=18), NMC-521 demonstrated a dose-dependent cytotoxic effect, achieving about a 65% reduction in tumor viability with an effective dose (ED50) of 10 µg/ml. Further insights were gained into NMC-521's mechanism of action using our ex vivo platform. The drug’s ability to induce tumor cell death in CT26 ex vivo was significantly reversed (p<0.01) when co-treated with α-NKG2D but not α-CD8, indicating a critical role for natural killer (NK) cells in its therapeutic effect. Complementing these findings, our analyses on freshly excised patient tumors (n=15) corroborated the cytotoxic effects of this drug on colorectal cancer but not to the same magnitude as in the CT-26 model. Furthermore, unlike the syngeneic murine tumor model, the response rate was (8 of 15 responsive patient tumors. Gene expression profiling indicated that NK cell-associated RNAs were elevated in NMC-521 treated PDOTS. Additionally, combination therapy studies using NMC-521 and nivolumab within our platform mirrored murine in vivo results, enhancing our understanding of the drug's potential in clinical settings. Intriguingly, an observed elevation in IL-15 levels in patient tumors treated with NMC-521 suggests an increased presence of NK cell activity when compared to treatments with nivolumab. This research underscores the potential of our organotypic tumor spheroids platform as a transformative tool in cancer drug development, offering an accurate and patient-specific method to evaluate new therapies, thereby increasing the likelihood of successful translation from the laboratory to patient care. Citation Format: Amir Aref, Alyssa Martin, Hamidreza Aboulkheyr Es, Patryk Krzesaj, Victor Adler, Kirti Khardenavis, Ehsan Sarafraz-Yazdi, Michael A. Perricone. Advanced ex vivo platform for drug response analysis: Evaluating the potent effects of NMC-521 mAb on mouse-and patient-derived organotypic tumor spheroids [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 LB218.

Tetracyclines enhance antitumor T-cell immunity via the Zap70 signaling pathway

BackgroundCancer immunotherapy including immune checkpoint inhibitors is only effective for a limited population of patients with cancer. Therefore, the development of novel cancer immunotherapy is anticipated. In preliminary studies, we...

Bispecific fibrous glue synergistically boosts vascular normalization and antitumor immunity for advanced renal carcinoma therapy

Immune checkpoint blockade therapy represented by programmed cell death ligand 1 (PD-L1) inhibitor for advanced renal carcinoma with an objective response rate (ORR) in patients is less than 20%. It is attributed to abundant tumoral vasculature with abnormal structure limiting effector T cell infiltration and drug penetration. We propose a bispecific fibrous glue (BFG) to regulate tumor immune and vascular microenvironments simultaneously. The bispecific precursor glue peptide-1 (pre-GP1) can penetrate tumor tissue deeply and self-assemble into BFG in the presence of neuropilin-1 (NRP-1) and PD-L1. The resultant fibrous glue is capable of normalizing tumoral vasculature as well as restricting immune escape. The pre-GP1 retains a 6-fold higher penetration depth than that of antibody in the multicellular spheroids (MCSs) model. It also shows remarkable tumor growth inhibition (TGI) from 19% to 61% in a murine advanced large tumor model compared to the clinical combination therapy. In addition, in the orthotopic renal tumor preclinical model, the lung metastatic nodules are reduced by 64% compared to the clinically used combination. This pre-GP1 provides a promising strategy to control the progression and metastasis of advanced renal carcinoma.

AutoPepVax, a Novel Machine-Learning-Based Program for Vaccine Design: Application to a Pan-Cancer Vaccine Targeting EGFR Missense Mutations.

The current epitope selection methods for peptide vaccines often rely on epitope binding affinity predictions, prompting the need for the development of more sophisticated in silico methods to determine immunologically relevant epitopes. Here, we developed AutoPepVax to expedite and improve the in silico epitope selection for peptide vaccine design. AutoPepVax is a novel program that automatically identifies non-toxic and non-allergenic epitopes capable of inducing tumor-infiltrating lymphocytes by considering various epitope characteristics. AutoPepVax employs random forest classification and linear regression machine-learning-based models, which are trained with datasets derived from tumor samples. AutoPepVax, along with documentation on how to run the program, is freely available on GitHub. We used AutoPepVax to design a pan-cancer peptide vaccine targeting epidermal growth factor receptor (EGFR) missense mutations commonly found in lung adenocarcinoma (LUAD), colorectal adenocarcinoma (CRAD), glioblastoma multiforme (GBM), and head and neck squamous cell carcinoma (HNSCC). These mutations have been previously targeted in clinical trials for EGFR-specific peptide vaccines in GBM and LUAD, and they show promise but lack demonstrated clinical efficacy. Using AutoPepVax, our analysis of 96 EGFR mutations identified 368 potential MHC-I-restricted epitope-HLA pairs from 49,113 candidates and 430 potential MHC-II-restricted pairs from 168,669 candidates. Notably, 19 mutations presented viable epitopes for MHC I and II restrictions. To evaluate the potential impact of a pan-cancer vaccine composed of these epitopes, we used our program, PCOptim, to curate a minimal list of epitopes with optimal population coverage. The world population coverage of our list ranged from 81.8% to 98.5% for MHC Class II and Class I epitopes, respectively. From our list of epitopes, we constructed 3D epitope-MHC models for six MHC-I-restricted and four MHC-II-restricted epitopes, demonstrating their epitope binding potential and interaction with T-cell receptors. AutoPepVax's comprehensive approach to in silico epitope selection addresses vaccine safety, efficacy, and broad applicability. Future studies aim to validate the AutoPepVax-designed vaccines with murine tumor models that harbor the studied mutations.

Neoadjuvant chemo-immunotherapy is improved with a novel pulsed electric field technology in an immune-cold murine model.

Chemo-immunotherapy uses combined systemic therapies for resectable and unresectable tumors. This approach is gaining clinical momentum, but survival increases leave considerable room for improvement. A novel form of Pulsed Electric Field (PEF) ablation combines focal tissue destruction with immune activation in preclinical settings. The PEFs induce lethal cell damage without requiring thermal processes, leaving cellular proteins intact. This affords PEF a favorable safety profile, improved antigenicity, and significant immunostimulatory damage-associated molecular pattern release compared to other focal therapies. Preclinical investigations demonstrate a combinatorial benefit of PEF with immunostimulation. This study evaluates whether this proprietary PEF therapy induces an immunostimulatory effect sufficient to augment systemic neoadjuvant chemotherapy and immunotherapy to reverse metastatic disease in an immune-cold murine tumor model. To determine whether PEF improves a neoadjuvant chemo-immunotherapy standard-of-care, partial PEF ablation was delivered to orthotopically inoculated 4T1 metastatic tumors in addition to combinations of cisplatin chemotherapy and/or αPD-1 immunotherapy, followed by resection. In addition, to determine whether PEF combined with chemo-immunotherapy improves local and metastatic response in unresectable populations, partial PEF ablation was added to chemo-immunotherapy in mice that did not receive resection. Blood cytokines and flow cytometry evaluated immune response. Partial PEF ablation generates an immunostimulatory tumor microenvironment, increases systemic immune cell populations, slows tumor growth, and prolongs survival relative to neoadjuvant systemic therapies-alone. These data suggest the addition of this proprietary PEF locoregional therapy may synergize with systemic standard-of-care paradigms to improve outcomes with potential or demonstrated metastatic disease in both resectable and unresectable patient cohorts.

Dual targeting of TIGIT and PD-1 with a novel small molecule for cancer immunotherapy

Immune checkpoint inhibitors have unveiled promising clinical prospects in cancer treatment. Nonetheless, their effectiveness remains restricted, marked by consistently low response rates and affecting only a subset of patients. The co-blockade of TIGIT with PD-1 has exhibited substantial anti-tumor effects. Notably, there is a dearth of reports on small-molecule inhibitors concurrently targeting both TIGIT and PD-1. In this study, we employed Microscale Thermophoresis (MST) to screen our laboratory's existing repository of small molecules. Our findings illuminated Gln(TrT) 's affinity for both TIGIT and PD-1, affirming its potential to effectively inhibit TIGIT/PVR and PD-1/PD-L1 pathways. In vitro co-culture experiments substantiated Gln(TrT)'s proficiency in restoring Jurkat T-cell functionality by blocking both TIGIT/PVR and PD-1/PD-L1 interactions. In the MC38 murine tumor model, Gln(TrT) emerges as a pivotal modulator, promoting the intratumoral infiltration and functional competence of CD8+ T cells. Furthermore, whether used as a monotherapy or in conjunction with radiotherapy, Gln(TrT) substantially impedes MC38 tumor progression, significantly extending the survival of murine subjects.

Abstract 1416: Resolvins enhance immunotherapy to induce Fanconi anemia tumor regression via inflammation resolution

Abstract Fanconi anemia (FA) is a disorder characterized by early-onset solid tumors unresponsive to chemotherapy and radiation. Unresolved inflammation is a hallmark of FA, the mechanisms underlying the initiation and resolution of inflammation in FA are poorly characterized. We hypothesized that FA tumor progression is controlled by dysregulated resolution metabolomes and a systemic pro-inflammatory eicosanoid storm of inflammation-initiating mediators. Using a novel transplantable murine FA tumor model, we show that Fancc-/- HNSCC (head and neck squamous cell carcinoma) progression disrupts the resolution of inflammation via an imbalance between specialized pro-resolving lipid mediators (SPMs) and eicosanoids. Fancc-/- tumor-bearing mice exhibited an increase in eicosanoids, including leukotriene B4 (LTB4) and thromboxane B2 (TXB2) in the spleen and a 113% increase in prostaglandin E metabolite (PGEM), a marker of PGE2 production, in the plasma compared to non-tumor-bearing (NT) mice. Fancc-/- tumor-bearing mice exhibited a loss in the SPM/LTB4 ratio including RvD1/LTB4, RvD2/LTB4, and MaR1/LTB4, compared to NT mice. Given the activity of immune checkpoint blockade in mismatch repair deficient tumors including head and neck cancers, immunotherapy may be relevant to FA-induced cancers. Importantly, the number of absolute T cells and CD4+ T cell function is preserved in individuals with FA. We combined stimulation of the resolution of inflammation (i.e., treatment with RvDs) with immunotherapy in a new transplantable murine FA tumor model. While treatment with RvD4, RvD5, or anti-PD1 immunotherapy alone delayed tumor growth compared to control at treatment day 20, the tumors did escape monotherapy by treatment day 30. Remarkably, RvD4 or RvD5 combined with anti-PD1 immunotherapy induced sustained Fancc-/- tumor regression. Moreover, RvD4 and/or anti-PD1 immunotherapy inhibited orthotopic Fancc-/- tumor growth compared to control. Resolvins and immune checkpoint blockade synergistically induced Fancc-/- tumor regression via macrophage phagocytosis of apoptotic debris, counter-regulation of pro-angiogenic cytokines, and inhibition of angiogenesis. Triggering Receptor Expressed on Myeloid cells-2 (TREM2)-antagonism combined with resolvins and immunotherapy restored SPM/eicosanoid ratios in Fancc−/- tumor-bearing mice to pre-cancer levels. SPMs and eicosanoids provide potential early biomarkers and biological targets in FA-induced cancer progression. Stimulating the resolution of inflammation via pro-resolution lipid mediators to enhance immunotherapy is a novel host-centric therapeutic approach to prevent FA-induced cancer progression via debris clearance and cytokine suppression. These results provide evidence for targeting the resolution of inflammation via resolvins to enhance immunotherapy to prevent and/or reverse FA-induced cancer progression. Citation Format: Katherine Quinlivan, Haixia Yang, Diane R. Bielenberg, Susanne I. Wells, Charles N. Serhan, Dipak Panigrahy. Resolvins enhance immunotherapy to induce Fanconi anemia tumor regression via inflammation resolution [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 1416.

Abstract 3255: Targeting CD4+FOXP3+ Tregs to enhance anti-tumor immunity

Abstract We strive to improve the outcomes of cancer immunotherapy by using a new generation of chemically modified self-delivering antisense oligonucleotides (ASO), termed FANA ASO, to target the key T-regulatory (Treg) cell transcription factor, FOXP3. We tested five murine FANA in 2 murine tumor models (TC1, MC38) and studied 19 human FANA FOXP3 in vitro with human healthy donor PBMC, followed by use of clinical samples from lung cancer patients and patients with mesothelioma, as well as testing in humanized mice (hu-PBMC-NSG). In murine studies, we treated mice on day 7 after tumor inoculation with Scramble control or murine FANA FOXP3, 50 mg/kg for 14 days, i.p. In the TC1 lung tumor model, we found an average 38% decrease of tumor volumes, p = 0.0007, and 22% of tumors were completely resorbed. In the MC38 colon carcinoma model, we found a 49% decrease of tumor volumes, p = 0.0182, and 13.6% of tumors were completely resorbed. In both tumor models, we observed an ~50% decrease of Foxp3 mRNA by qPCR, and decreased numbers of intratumoral Tregs by flow cytometry. This was accompanied by significant decreases (p<0.05) of the mRNA and protein intratumoral levels of multiple exhaustion markers: LAG-3, CTLA-4, PD-1, Tim-3, Tigit, CD244, CD160 and VISTA, and increased expression of perforin and granzyme-b by intratumoral T cells. In addition, there were no changes in FOXP3 mRNA expression or in the numbers of Tregs in draining lymph nodes and in spleens of tumor bearing mice, suggesting that intratumoral Treg have enhanced sensitivity to FANA FOXP3 in vivo. We identified the best 5 of 19 human FANA FOXP3 and showed these had no toxic effects on cell viability or division, and downregulated FOXP3 expression over 50% in PBMC from healthy donors (p<0.05). Human Treg, pre-incubated with FANA FOXP3 for 3 hours, retained only 60.3% of their suppressive function in vitro. FANA FOXP3 treatment of lung cancer tumor samples and mesothelioma pleural effusion samples resulted in a 56.4% decrease in FOXP3 mRNA expression and a 61.5% decrease in Treg numbers (all p<0.05). Moreover, tumor FOXP3+ Treg had 36.7% less FOXP3 protein per cell, and downregulated CD39 expression compared to Scramble control. Targeting of cancer samples with human FANA FOXP3 in vitro was associated with increased division of CD4+ and CD8+ cells, and with downregulation of multiple exhaustion molecules, including CTLA-4, Tim-3, PD-1, LAG-3 and TIGIT. Humanized mice, treated with two human FANA FOXP3 compounds (50 mg/kg, 7days), demonstrated an absence of apparent toxic effects and human FOXP3 mRNA was downregulated by 47.4% in the blood, by 74.2% in lymph nodes and by 51.8% in the spleens (all p<0.05). Hence, targeting of intratumoral Tregs using FANA FOXP3 results in enhanced immune responses to solid tumors without inducing autoimmunity, and studies are underway in combination with checkpoint inhibitors and/or CAR-T cell therapy. Citation Format: Tatiana Akimova, Liqing Wang, Zhanna Bartosh, Evgeniy Eruslanov, Steven Albelda, Sunil Singhal, Veenu Aishwarya, Wayne W. Hancock. Targeting CD4+FOXP3+ Tregs to enhance anti-tumor immunity [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 3255.

Abstract 2879: Spatiotemporal fractionation: An innovative concept of fractionated radiotherapy

Abstract Impressive outcomes in therapeutic radiation oncology have been achieved in the past decade through the development of advanced computer technology and imaging methods, such as intensity modulated radiotherapy. Ideally, radiotherapy treatment delivers a high dose to the tumor while sparing the surrounding healthy tissues and organs at risk from radiation damage. Spatiotemporal Fractionated Radiotherapy has emerged as an innovative technique that delivers different dose distributions to different parts of the tumor in order to achieve high doses to the target while ensuring a low dose-bath in the surrounding normal tissue. Spatiotemporally fractionated regimens showed in silico up to 10 - 15% sparing of normal tissue from radiation damage, while ensuring isoeffective tumor control compared to conventionally fractionated regimens. However, prior to advancing spatiotemporal fractionation to the clinical level, it is important to probe the validity of the main assumption of spatiotemporal fractionation derived from the Biologically Effective Dose (BED) model: two different fractionation schemes that implement a high and a low dose will lead to equivalent clinical effects, regardless of dose-treatment sequence. A tumor growth delay study was performed in a subcutaneous immunocompetent murine tumor model (MC38-tumor cell derived) receiving two different fractionation regimens. Particularly, tumors belonging to the two treatment groups received the same dose combination - a high (12 Gy) and a low (6 Gy) dose fraction separated by 72 hours - with the doses delivered in opposite order in the two treatment groups. The same experimental outline was performed in a subcutaneous immunodeficient murine tumor model derived from the same tumor cells. Tumors were also characterized by immunophenotyping analysis seven days after first irradiation. Even though the two regimens deliver the same physical dose to the tumor - and would be considered equivalent according to the BED model - different tumor growth delays were observed in a time window of 30 days after first irradiation depending on the treatment group. Such differences were observed in the immunocompetent model but not in the immunodeficient model. The immunophenotyping results showed immunostimulatory vs immunosuppressive phenotypes of the tumor microenvironment depending on the order of the treatment doses. An additional tumor growth delay study including immune checkpoint inhibitors confirmed the fundamental role of the immune system with the differential efficacy outcomes of the two regimens. Overall, these intriguing results suggest that a differential radiotherapy-induced immune response to different doses of ionizing radiation plays an important role in the treatment outcome and asks for re-evaluation of the BED model taking scheduling-dependent parameters into consideration. Citation Format: Irene Vetrugno, Irma Telarovic, Nathan Torelli, Jan Unkelbach, Martin Pruschy. Spatiotemporal fractionation: An innovative concept of fractionated radiotherapy [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 2879.

Abstract 52: CRISPR-mediated knock-out of A20 lowers the activation threshold and induces metabolic rewiring of CAR-T cells

Abstract Background: Common failures of chimeric antigen receptor (CAR)-T cell therapy regimens stem from immune escape of target antigen low tumors. Strategies to improve CAR-T cell therapy efficacy include enhancing intrinsic effector function while preventing T cell exhaustion. The ubiquitin-modifying enzyme A20, is a key negative regulator of the NF-kB pathway downstream of T cell receptor activation in T cells. Dysfunctional CD8 T cells in tumors have high expression of A20, and deletion of A20 enhances antitumor activity of CD8 T cells in murine tumor models. We tested whether CRISPR-mediated knock-out (KO) of tumor necrosis factor α-induced protein 3 (TNFAIP3), the gene for A20, increases the effector function and alters the metabolic state of CAR-T cells. Results: A20 deletion led to upregulation of NF-κB target genes and resulted in higher levels of activation marker expression and effector cytokine secretion compared to unarmored CAR-T upon incubation with target cells. In addition, A20 KO CAR-T cells maintained prolonged expression of activation markers upon antigen clearance in the absence of enhanced differentiation, and were more resistant to dysfunction in a repeat challenge serial kill assay. In vivo, A20 deficient CAR-T exhibited increased anti-tumor efficacy against low, medium, and high target expressing tumor models. Consistent with NF-κB upregulation, A20 KO cells significantly upregulated key glycolytic intermediates suggesting that amino acid anabolism was fueled by glycolysis and the pentose phosphate pathway. Moreover, the preferential increase of glycolysis over oxidative phosphorylation confirmed that A20 KO CAR-T cells were skewed towards an effector-like phenotype. Notably, glutathione and its cysteine-glycine bi-products were upregulated upon activation to a higher level in A20 KO CAR-T suggesting enhanced resistance to oxidative stress, in line with their prolonged persistence. Conclusions: CRISPR-mediated knock-out of A20 lowers the activation threshold of CAR-T cells producing enhanced in vitro and in vivo anti-tumor efficacy particularly against tumors with very low levels of target expression. A20 KO induces metabolic rewiring of CAR-T cells by promoting glycolysis and amino acid anabolism to sustain their superior effector functions. This intrinsic armoring strategy can be applied to any CAR-T in any indication to increase tumor control and reduce immune escape. Citation Format: Nina Jia Chu, Carina Nava-Barbero, Ashley Merlino, Ping-Hsien Lee, David Baker, Ben Taylor, Gordon Moody, Letizia Giardino. CRISPR-mediated knock-out of A20 lowers the activation threshold and induces metabolic rewiring of CAR-T cells [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 52.

Abstract 5322: Discovery of CRD1601, a potent and selective HPK1 inhibitor with robust in vivo anti-cancer activity

Abstract Background: Haematopoietic Progenitor Kinase (HPK-1, MAP4K1) is a member of the STE20 family of serine/threonine kinases, expressed predominantly in hematopoietic cells. HPK-1 functions as a negative regulator of T-cell and B-cell receptor activation by triggering proteasomal degradation and disrupting signalosome complexes downstream of TCR and BCR. HPK1 inhibition is a novel IO strategy that could combine with existing chemotherapies and immunotherapies. Methods: Curadev used a pharmacophore based approach to discover novel small molecule HPK-1 inhibitors using in vitro enzymatic and phenotypic cellular screens using primary cells. CRD1601, the clinical candidate was selected based on its ability to enhance human T-cell proliferation through the induction of IL2 and IFNγ. Syngeneic tumor models were used to assess anti-tumor activity of selected compounds as a monotherapy or combination therapy. Results: CRD1601 is a potent HPK1 inhibitor with a single digit nanomolar IC50 value in enzymatic assay and potent cellular activity in the SLP76 assay. A single dose of CRD1601 in mice treated with an anti-CD3 antibody caused systemic enhancement of pro-inflammatory cytokines such as IL2, IFN gamma and reduced pSLP76 levels in the spleen. Further, CRD1601 reversed the immunosuppressive effect of PGE2 and NECA. CRD1601 demonstrated significant single agent activity in murine tumor models while also synergizing with chemotherapy and immunotherapy. Conclusions: Inhibition of HPK-1 is a promising therapeutic modality that could augment the effects of existing anti-cancer treatments including immunotherapy. CRD1601 is a potent and selective HPK-1 inhibitor with favorable drug like properties that has been selected from a rich portfolio of active compounds and shows promising in vivo activity in tumor models. Citation Format: Monali Banerjee, Ritesh Shrivastava, David Pryde, Sandip Middya, Sabyasachi Debnath, Anindita Middya, Dharmendra Yadav, Nidhi Rawat, Rajib Ghosh, Manisha Padaliya, Sourav Basu, Arjun Surya. Discovery of CRD1601, a potent and selective HPK1 inhibitor with robust in vivo anti-cancer activity [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 5322.