Bromodomains (BD) are epigenetic readers of histone acetylation involved in chromatin remodeling and transcriptional regulation of several genes including protooncogene cellular myelocytomatosis ...(c-Myc). c-Myc is difficult to target directly by agents due to its disordered alpha helical protein structure and predominant nuclear localization. The epigenetic targeting of c-Myc by BD inhibitors is an attractive therapeutic strategy for prostate cancer (PC) associated with increased c-Myc upregulation with advancing disease. MT-1 is a bivalent BD inhibitor that is 100-fold more potent than the first-in-class BD inhibitor JQ1. MT-1 decreased cell viability and causes cell cycle arrest in G0/G1 phase in castration-sensitive and resistant PC cell lines in a dose-dependent fashion. The inhibition of c-Myc function by MT-1 was molecularly corroborated by the de-repression of Protein Kinase D1 (PrKD) and increased phosphorylation of PrKD substrate proteins: threonine 120, serine 11, and serine 216 amino acid residues in β-Catenin, snail, and cell division cycle 25c (CDC25c) proteins, respectively. The treatment of 3D cell cultures derived from three unique clinically annotated heavily pretreated patient-derived PC xenografts (PDX) mice models with increasing doses of MT-1 demonstrated the lowest IC
in tumors with c-Myc amplification and clinically resistant to Docetaxel, Cabazitaxel, Abiraterone, and Enzalutamide. An intraperitoneal injection of either MT-1 or in combination with 3jc48-3, an inhibitor of obligate heterodimerization with MYC-associated protein X (MAX), in mice implanted with orthotopic PC PDX, decreased tumor growth. This is the first pre-clinical study demonstrating potential utility of MT-1 in the treatment of PC with c-Myc dysregulation.
BackgroundPatients with relapsed and metastatic osteosarcoma have a 5 year overall survival <25%. Our group tested our novel multilamellar RNA lipid nanoparticle aggregate vaccine (RNA-LPA)1 as an ...approach to reprogram the immunosuppressive tumor microenvironment (TME)2 present in osteosarcoma, where immunotherapy has not yet been effective.MethodsTotal-tumor mRNA was amplified from tumor cell lines in mice or tumor biopsy in canines before complexation in lipid nanocarriers/cationic lipids, generating RNA-LPA for systemic administration. Preclinical murine models were generated using K7M2, KHOS or 143B osteosarcoma cells in either C57Bl/6, BALB/c or BALB/c SCID mice inoculated by tail vein injection to mimic minimal residual metastatic disease from pulmonary osteosarcoma. We treated client-owned canine patients (pet-dogs) with osteosarcoma through a comparative oncology clinical trial with the UF College of Veterinary Medicine (UF IACUC#202111376, PI: Milner). Using liquid-like solid (LLS) 3D tumoroid culture system,3 we established ex vivo models of murine, canine, and human osteosarcoma.ResultsTumor-specific RNA-LPAs elicited anti-tumor efficacy in the murine K7M2 model with long term survival (7/8 mice), with some survival benefit even with irrelevant pp65 RNA-LPAs (p<0.05); these findings correlated with an increase in intratumoral central memory T cells. Both tumor-specific and irrelevant RNA-LPAs reprogramed the innate immune microenvironment (decreased tumor associated macrophages and myeloid derived suppressor cells, p<0.01), but tumor-specific RNA-LPAs additionally resulted in activation of adaptive immunity (dendritic cells and T-cells). Five pet-dogs with osteosarcoma were safely treated with total-tumor RNA-LPAs, which were immunologically active, demonstrating changes in complete blood counts and serum cytokines within 6 hours of vaccine administration. One pet dog received 4 total RNA-LPAs every 2 weeks with initial objective radiographic resolution of pulmonary metastases, though this subject relapsed with new metastases. Osteosarcoma tumors from mice, canines, and human patients were used to successfully establish 3D tumoroid tissue culture for at least 32 days ex vivo.ConclusionsBoth tumor-specific and nonspecific ‘off the shelf’ RNA-LPA vaccines redirected immunosuppressive myeloid cells, a hallmark of the osteosarcoma TME.2 This agent, which is FDA-IND approved (BB-19304, Sayour) and in human clinical trials for patients with brain tumors (NCT04573140) will enter clinical trials for patients with osteosarcoma in the coming year (NCT04837547, not yet recruiting). Our 3D tumoroid system offers the opportunity to study the immune-modulating effect of RNA-LPAs and may be a meaningful correlate to both canine and human subjects enrolled on clinical trials.AcknowledgementsWe appreciate funding from the National Cancer Institute, the V Foundation, MIB Agents, Hyundai Hope on Wheels, and the Pediatric Cancer Research Foundation.Trial RegistrationNCT04573140ReferencesMendez-Gomez H, DeVries A, Castillo P, Stover B, Qdaisat S, Von Roemling C, Ogando-Rivas E, Weidert F, McGuiness J, Zhang D, Chung MC, Li D, Zhao C, Marconi C, Campaneria Y, Chardon-Robles J, Grippin A, Karachi A, Thomas N, Huang J, Milner R, Sahay B, Sawyer WG, Ligon JA, Silver N, Simon E, Cleaver B, Wynne K, Hodik M, Molinaro A, Guan J, Kellish P, Doty A, Lee J-H, Carrera-Justiz S, Rahman M, Gatica S, Mueller S, Prados M, Ghiaseddin A, Mitchell DA, Sayour EJ. mRNA aggregates harness danger response for potent cancer immunotherapy. medRxiv. 2023:2023.03.12.23287108. doi: 10.1101/2023.03.12.23287108.Ligon JA, Choi W, Cojocaru G, Fu W, Hsiue EH, Oke TF, Siegel N, Fong MH, Ladle B, Pratilas CA, Morris CD, Levin A, Rhee DS, Meyer CF, Tam AJ, Blosser R, Thompson ED, Suru A, McConkey D, Housseau F, Anders R, Pardoll DM, Llosa N. Pathways of immune exclusion in metastatic osteosarcoma are associated with inferior patient outcomes. Journal for immunotherapy of cancer. 2021;9(5). doi: 10.1136/jitc-2020–001772. PubMed PMID: 34021032; PMCID: PMC8144029.Bhattacharjee T, Gil CJ, Marshall SL, Urueña JM, O’Bryan CS, Carstens M, Keselowsky B, Palmer GD, Ghivizzani S, Gibbs CP, Sawyer WG, Angelini TE. Liquid-like Solids Support Cells in 3D. ACS Biomater Sci Eng. 2016;2(10):1787–95. Epub 20160620. doi: 10.1021/acsbiomaterials.6b00218. PubMed PMID: 33440476.Ethics ApprovalStudies approved by UF IACUC 202111376 and 202009941, and UF IRB202001062
BackgroundDiffuse midline glioma (DMG) is a universal fatal glial brain cancer in children. We tested our novel multilamellar mRNA lipid particle aggregate vaccine (RNA-LPA, IND19304—Sayour),1 a ...tumor-agnostic treatment platform that encapsulates tumor specific RNA and delivers the payload in a highly immunogenic fashion, as an approach to treating this currently incurable cancer.MethodsUsing the K2 DMG model,2 we implant H3K27M-expressing DMG cells into the 4th ventricle of P1-P3 neonatal C57BL/6 mice. RNA-LPA generated from predicated human H3K27M epitopes or total-tumor mRNA are administered intravenously beginning at day 35. We performed multiparameter 3D geospatial fluorescent microscopy to characterize mRNA transduction. Immunologic responses to treatment were evaluated by multiparameter flow cytometry, microscopy, and cytokine profiling.ResultsMice developed clinical neurological signs of disease by day 30–35. RNA-LPAs targeting human H3K27M epitopes were found to be immunogenic in wild-type mice. Intriguingly, nonspecific enhanced green fluorescent protein (eGFP)-RNA-LPAs resulted in statistically significant survival benefits compared to mice treated with empty LPs. However, tumor-specific RNA-LPAs (either H3K27M-specific or total tumor mRNA-derived) also enhanced survival and additionally resulted in a subset of mice with long-term survival. This survival benefit was observed despite the development of clinical hydrocephalus in mice treated with RNA-LPAs. 3D microscopy established that tumors demonstrated invasive disease and microvascular erosion in mice. We found that mRNA transduces fibroblastic reticular cells (FRCs) in the spleen and lymph nodes, prompting widespread immune activation. Treatment with RNA-LPA led to massive increases in production inflammatory cytokines (i.e. TNF-α) and chemokines (i.e. CCL2), which led to recruitment of the majority of circulating monocytes and lymphocytes to secondary lymphoid organs.ConclusionsRNA-LPAs extend survival in our highly aggressive DMG model, including curative outcomes in cohorts treated with either total tumor or H3K27M RNA-LPs. These data suggest that RNA-LPs are capable of stimulating host adaptive immune responses against established DIPG tumors. Signs of hydrocephalus in treated mice may indicate pseudoprogression due to immunologic response, yet mice were frequently able to survive this development. Future studies will further characterize the immunologic response in these mice and support expansion of our existing IND for a multi-institutional phase I clinical trial for children with DMG, who currently have no curative options.AcknowledgementsWe appreciate funding from the ChadTough Defeat DIPG Foundation and the DIPG/DMG Research Funding Alliance. John Ligon and Elias Sayour contributed equally and are co-senior authors.ReferencesMendez-Gomez H, DeVries A, Castillo P, Stover B, Qdaisat S, Von Roemling C, Ogando-Rivas E, Weidert F, McGuiness J, Zhang D, Chung MC, Li D, Zhao C, Marconi C, Campaneria Y, Chardon-Robles J, Grippin A, Karachi A, Thomas N, Huang J, Milner R, Sahay B, Sawyer WG, Ligon JA, Silver N, Simon E, Cleaver B, Wynne K, Hodik M, Molinaro A, Guan J, Kellish P, Doty A, Lee J-H, Carrera-Justiz S, Rahman M, Gatica S, Mueller S, Prados M, Ghiaseddin A, Mitchell DA, Sayour EJ. mRNA aggregates harness danger response for potent cancer immunotherapy. medRxiv. 2023:2023.03.12.23287108. doi: 10.1101/2023.03.12.23287108.Misuraca KL, Cordero FJ, Becher OJ. Pre-Clinical Models of Diffuse Intrinsic Pontine Glioma. Front Oncol. 2015;5:172. doi: 10.3389/fonc.2015.00172. PubMed PMID: 26258075; PMCID: PMC4513210.Ethics ApprovalWork approved under UF IACUC 202200000375
Abstract
BACKGROUND
High-grade gliomas are an aggressive subset of CNS tumors in need of novel treatment strategies. However, tumor heterogeneity, the immunosuppressive tumor microenvironment (TME) ...and the lack of immunogenic tumor specific targets have limited the translational power of many immunotherapies for high-grade gliomas. The promising application of mRNA vaccines has the potential to restore immunosurveillance through peripheral and intratumoral reprograming of the TME.
METHODS
Our lab has developed a lipid particle multilamellar aggregate (RNA-LPA) vaccine that encapsulates tumor specific RNA and delivers the payload to the immune system in a highly immunogenic fashion, similar to that of a virus. We sought to assess anti-tumor activity across preclinical murine models and investigate the mechanisms for response.
RESULTS
We demonstrated the immune activation potential of RNA-LPAs encoding for glioma associated antigens (i.e., pp65 and H3K27M) in preclinical murine models. We also showed activity of personalized RNA-LPA in canine and human studies (NCT04573140) for patients with high-grade gliomas. Exogenous RNA is recognized by pathogen recognition receptors (PRRs) which trigger a type I interferon (IFN) response and proinflammatory cytokine production. While most RNA based vaccines activate an innate immune response primarily through toll-like receptor 7 (TLR7), we reveal that RNA-LPAs activate the innate immune system through retinoic acid-inducible gene 1 protein (RIG-I). As a result of PRR signaling, the type I IFN and cytokine/chemokine response (IL-6, G-CSF, TNF-alpha, CXCL9, CXCL10, CCL2, CCL4) mediates massive recruitment of activated dendritic cell and activated T cell in lymphoreticular organs where antigen presenting cells and cytolytic T cell colocalize to initiate an adaptive immune response against glioma specific antigens.
CONCLUSION
RNA-LPAs are a novel platform immunotherapy that initiate anti-tumor immunity against malignant brain tumors through noncanonical activation of intracellular PRRs and widespread recruitment of peripheral blood mononuclear cells to sites of RNA-LPA localization.
Abstract
BACKGROUND
Recurrent PCNSBLs represent a therapeutic challenge. Up to 60% of PCNSBL patients relapse to later face survival rates as low as 22%. Unfortunately, tumor heterogeneity and ...off-target effects have limited the success of immunotherapy against PCNSBL.
METHODS
We propose a novel immunotherapy to overcome PCNSBL heterogeneity and off-target effects in an exquisitely tumor specific manner using nanoparticle vaccination, capable of delivering personalized tumor derived mRNAs, that induces systemic orchestration of innate and adaptive immunity. We target tumor antigens derived from the B cell receptor (i.e., heavy chain immunoglobulin - IgH) clonotypes. IgH clonotypes are hypervariable gene rearrangements clonally generated by B cells. Tumor IgH clonotypes are unique for each malignant B cell clone and hence attractive immune targets, not shared by normal B cell clones avoiding undesirable off-target effects.
RESULTS
RNA-NPs can reprogram tumor microenvironment while activating the innate immunity via IFN type I (i.e., IFNα) and priming of hypervariable region clonotype specific T cell responses in naïve mice. We determined the rearranged IgH sequences (predominant clone 99% and nine additional clones with frequencies < 1%) of clinically relevant inbred murine PCNSBL models (BAL17 and A20) by PCR. The number of identified clonotypes confirmed the IgH variability observed in human B cell hematological malignancies. In preliminary experiments targeting lymphoma derived single clonotypes with RNA-NPs, we showed the feasibility of priming in-vivo T cells specific against hypervariable regions after 3 weekly i.v. RNA-NPs (median IFNγ: 58 pg/ml; range: 50-70 pg/ml vs controls < 30 pg/ml; p=0.008). Targeting of clonotype RNA-NPs was associated with decreased tumor growth (p=0.04). Interestingly, we have observed tumor reactive lymphangiogenesis that communicates with regional skull bone marrow observed in 3D microscopy that might direct future routes of RNA-NP administration.
CONCLUSION
Our RNA-NP systemic vaccination platform can induce PCNSBL clonotype specific T cell responses, sparing normal tissues.
Abstract
Bromodomains (BD) are epigenetic readers of histone acetylation involved in chromatin remodeling and transcriptional regulation of protooncogene cellular myelocytomatosis (c- Myc) and other ...genes. Because c-Myc cannot be directly targeted by small molecular inhibitors due to disordered alpha helical structure, epigenetic targeting of c-Myc by BD inhibitors is an attractive therapeutic strategy for diseases such as prostate cancer (PC) associated with increased c-Myc upregulation with advancing disease. We studied the efficacy of MT1, a novel bivalent BD inhibitor that is 100-fold more potent than the first in class BD inhibitor JQ1, at inhibiting PC growth. We tested the effect on viability by MT-1 on PC cell lines, 3D spheroids derived from clinically annotated drug resistant patient derived xenografts (PDX), mice PDX models and corroborated the molecular mechanism of MT1 down regulation of Myc leading to downstream Myc-dependent up regulation of Protein Kinase D1 (PrKD) substrate phosphorylation by western blot. MT-1 inhibited growth of PC in castration sensitive (LNCaP) and resistant PC cells (PC-3). MT-1 treatment upregulated PrKD expression and phosphorylation of known PrKD substrates: threonine 120 (Thr-120) residues in beta-catenin and the serine 216 in Cell Division Cycle 25 (CDC25C) in PC-3 cells. Moreover, MT-1 was effective in inhibition of 3D spheroids growth at IC 50 between 0.27-0.92µM in Abiraterone, Enzalutamide, Docetaxel, Cabazitaxel metastatic castrate resistant PCa patient-derived tumor 3D spheroids. Additionally, MT1 was effective in inhibiting the tumor growth in PDX mice model. A combined intra-peritoneal administration of MT-1 with another c-Myc inhibitor (3JC48-3), an obligate c-Myc and MYC-associated protein X (MAX) heterodimerization inhibitor, increased the efficacy of inhibiting the PDX growth in mice. This study provides strong pre-clinical in vitro and in vivo evidence for advancing MT- 1 as a novel c-Myc targeting drug in PC. The MT-1 drug development will likely be highly impactful as c-Myc is dysregulated in three fourths of men with advanced PC.
Citation Format: Sanjeev Shukla, Mohammed Al-Toubat, Allison H. Feibus, Ahmed Elshafei, Carlos Riveros, Nathalie Meurice, Justyna Gleba, Jonathan Chardon-Robles, Adam M. Kase, John A. Copland III, Joachim L. Petit, Teruko Osumi, K.C. Balaji. Bromodomain inhibitor: MT1 and its potential role in modulation of prostate cancer progression abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2475.
