Targeting PELP1 Attenuates Angiogenesis and Enhances Chemotherapy Efficiency in Colorectal Cancer

Abnormal angiogenesis is one of the important hallmarks of colorectal cancer as well as other solid tumors. Optimally, anti-angiogenesis therapy could restrain malignant angiogenesis to control tumor expansion. PELP1 is as a scaffolding oncogenic protein in a variety of cancer types, but its involvement in angiogenesis is unknown. In this study, PELP1 was found to be abnormally upregulated and highly coincidental with increased MVD in CRC. Further, treatment with conditioned medium (CM) from PELP1 knockdown CRC cells remarkably arrested the function of human umbilical vein endothelial cells (HUVECs) compared to those treated with CM from wildtype cells. Mechanistically, the STAT3/VEGFA axis was found to mediate PELP1-induced angiogenetic phenotypes of HUVECs. Moreover, suppression of PELP1 reduced tumor growth and angiogenesis in vivo accompanied by inactivation of STAT3/VEGFA pathway. Notably, in vivo, PELP1 suppression could enhance the efficacy of chemotherapy, which is caused by the normalization of vessels. Collectively, our findings provide a preclinical proof of concept that targeting PELP1 to decrease STAT3/VEGFA-mediated angiogenesis and improve responses to chemotherapy due to normalization of vessels. Given the newly defined contribution to angiogenesis of PELP1, targeting PELP1 may be a potentially ideal therapeutic strategy for CRC as well as other solid tumors.

APPLICATION OF THE PONTRYAGIN MAXIMUM PRINCIPLE TO CONTROL TUMOR ANGIOGENESIS

We present a sample application covering several cases using an extension of the Pontryagin Minimum Principle (PMP) [3]. We are interested in the management of tumor angiogenesis, that is, the therapeutic management of the proliferation of cancer cells that develop new blood vessels. Let us formulate the problem and derive the optimal control and apply the Pontryagin maximum principle to our optimal trajectory, and we derive the theorem and check it with an example. Then we will study stabilization.

Targeting Innate Immunity in Breast Cancer Therapy: A Narrative Review

Although breast cancer has been previously considered “cold” tumors, numerous studies are currently conducted to explore the great potentials of immunotherapies in improving breast cancer patient outcomes. In addition to the focus on stimulating adaptive immunity for antitumor responses, growing evidence showed the importance of triggering host innate immunity to eradicate established tumors and/or control tumor metastasis of breast cancer. In this review, we first briefly introduce the breast tumor immune microenvironment. We also discuss innate immune targets and pathways and mechanisms of their synergy with the adaptive antitumor response and other treatment strategies. Lastly, we review clinical trials targeting innate immune pathways for breast cancer therapies.

VISTA Is a Diagnostic Biomarker and Immunotherapy Target of Aggressive Feline Mammary Carcinoma Subtypes

Feline mammary carcinoma (FMC) is a common neoplasia, showing aggressive clinicopathological features, without viable therapeutic options. The study of tumor microenvironment has gained importance, due to the ability to control tumor progression by regulating the immune response. Considering the lack of knowledge, feline serum VISTA levels from cats with mammary carcinoma were compared with healthy controls, and with serum levels of PD-1/PD-L1, CTLA-4, LAG-3, IL-6, and TNF-α. In parallel, VISTA tumor expression was evaluated in FMC samples. The obtained data revealed that serum VISTA levels were significantly higher in cats presenting HER2-positive (p = 0.0025) or triple-negative subtypes (p = 0.0019), with higher serum levels in luminal A (p = 0.0025) correlated to the presence of metastasis (p = 0.0471). Furthermore, in HER2-positive or triple-negative tumors, correlations were obtained between serum VISTA levels and the serum levels of the above-mentioned molecules. In tumors, VISTA expression revealed a stronger intensity in cancer cells, when compared to TILs (p < 0.0001). Stratifying the samples by subtypes, a higher number of VISTA-positive TILs was observed in the HER2-positive subtype, compared with triple-negative tumors (p = 0.0138). In conclusion, results support the development of therapeutic strategies for HER2-positive and triple-negative FMC subtypes, reinforcing the use of cats as a human oncology model.

Mitoxantrone-Loaded Nanoferritin Slows Tumor Growth and Improves the Overall Survival Rate in a Subcutaneous Pancreatic Cancer Mouse Model

Pancreatic cancer (PC) represents an intriguing topic for researchers. To date, the prognosis of metastasized PC is poor with just 7% of patients exceeding a five-year survival period. Thus, molecular modifications of existing drugs should be developed to change the course of the disease. Our previously generated nanocages of Mitoxantrone (MIT) encapsulated in human H-chain Ferritin (HFt), designated as HFt-MP-PASE-MIT, has shown excellent tumor distribution and extended serum half-life meriting further investigation for PC treatment. Thus, in this study, we used the same nano-formulation to test its cytotoxicity using both in vitro and in vivo assays. Interestingly, both encapsulated and free-MIT drugs demonstrated similar killing capabilities on PaCa44 cell line. Conversely, in vivo assessment in a subcutaneous PaCa44 tumor model of PC demonstrated a remarkable capability for encapsulated MIT to control tumor growth and improve mouse survival with a median survival rate of 65 vs. 33 days for loaded and free-MIT, respectively. Interestingly, throughout the course of mice treatment, MIT encapsulation did not present any adverse side effects as confirmed by histological analysis of various murine tissue organs and body mass weights. Our results are promising and pave the way to effective PC targeted chemotherapy using our HFt nanodelivery platforms.

420 PROSTVAC in combination with nivolumab enhanced immune cell infiltration in prostate cancer

BackgroundProstate cancer (PC) is the most common non-cutaneous diagnosed cancer among men in USA.1 Although clinical outcomes are favorable for patients with localized disease, 20–30% of patients will develop metastatic prostate cancer (mPC) and have poor prognosis. Immunotherapy, as a single agent, provides benefit to a small subset of PC patients, which is thought to be partially due to its known cold tumor immune microenvironment (TIME). Combination studies are needed to enhance benefit.2 Prostvac is a therapeutic cancer vaccine engineered to activate an immune response against prostate-specific Antigen (PSA).3 Prostvac alone could induce systemic immune response by increasing immune-cell infiltrates in and around the tumor.4 In this study, we are exploring the effect of Prostvac in combination with nivolumab in TIME in prostate cancer.MethodsWe treated locally advanced prostate cancer patients (n=6) undergoing radical prostatectomy (RP) with neoadjuvant Prostvac in combination with nivolumab, an immune checkpoint PD-1 inhibitor. Dynamic changes in TIME before and after treatment were studied using multiplex immunofluorescence (Opal Method). Formalin fixed paraffin-embedded sections from matched pre-treated prostate biopsies and post-treated RP samples were stained with a validated T cell panel (DAPI, CD4, CD8, FOXP3, Ki67, Pan CK and PD-L1). To analyze the data, TIME was segmented into 3 compartments: intratumoral, invasive margin and benign.ResultsCombination immunotherapy significantly increased CD4+ T cell density in the invasive margin (mean 211.5 cells/mm2 vs 592.2 cells/mm2, p<0.05), with similar trend in the intratumoral and the benign compartments. CD8+ T cell density increased after treatment in the invasive margin (mean 47.25 cells/mm2 vs 157cells/mm2) and the benign compartment. 5/6 and 4/6 patients showed more than 2-fold increase of CD4 and CD8 T cells in the TIME, respectively, in at least one of the three compartments. Increased proliferative indices in CD4+ and CD8+ T cells were also seen after treatment. Tregs were present in low frequencies in TIME (maximum of 12 cells/mm2) with no significant changes. Moreover, a significant drop in tumor cell Ki67 after treatment (mean 252.8 cells/mm2 vs 100.5 cells/332, p<0.05) suggests that the combination may control tumor growth.ConclusionsThe combination of Neoadjuvant Prostvac and nivolumab was associated with increased immune cell infiltration in a cohort of early prostate cancer patients. A broader examination of the TIME and the role immune cells undertake to control tumor growth is on-going.Trial RegistrationNCT02933255ReferencesSiegel RL, Miller KD, Jemal A. Cancer statistics, 2020. CA Cancer J Clin (Internet) 2020;70:7–3Zhao SG, Lehrer J, Chang SL, et al. The immune landscape of prostate cancer and nomination of PD-L2 as a potential therapeutic target. J Natl Cancer Inst 2018;111:301–10.Madan RA, Arlen PM, Mohebtash M, et al. Prostvac-VF: a vectorbased vaccine targeting PSA in prostate cancer. Expert Opin Investig Drugs 2009;18:1001–11Abdul Sater H, Marté JL, Donahue RN, et al. Neoadjuvant PROSTVAC prior to radical prostatectomy enhances T-cell infiltration into the tumor immune microenvironment in men with prostate cancer. J Immunother Cancer 2020;8(1):655–64Ethics ApprovalThis study was performed in compliance with ethical standard and was approved by the NIH IRB, 17C-0007. All patients participating in this study gave an informed consent before taking part.

895 Discovery of a safer 4–1BB agonist by targeting a membrane-proximal epitope combined with bispecific-mediated cross-bridging

BackgroundCheckpoint inhibitors towards cytotoxic T-lymphocyte protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) have paved the way for a new frontier of anti-cancer therapies that modulate our pre-existing immune system to fight against malignancies. 4-1BB is a tumor-necrosis superfamily member expressed on NK and T cells, that acts as a co-stimulatory receptor to improve effector/memory responses towards tumors. Early efforts have focused on the generation of agonist antibodies towards 4-1BB that relied on Fc-mediated cross-linking to cluster and induce receptor downstream signaling, but has led to liver- and immune-related toxicities. We have discovered a PD-L1 x 4-1BB bispecific that exhibits conditional agonist activity in the presence of PD-L1 with better safety features.Methods vHH binders to PD-L1 and 4-1BB were generated from immune libraries derived from camelids and selected via yeast display. Antibody screening was carried out by protein-protein interaction analysis and cell-based binding. Target-related activity was confirmed using luciferase reporter assays. Primary immune cells were also tested for T cell activation via the detection of IL-2 and IFNg secretion. PD-L1-mediated 4-1BB activation via cross-bridging was carried out using target cells expressing PD-L1 co-cultured with effector cells. X-ray crystallography was conducted to resolve the binding sites of both the anti-PD-L1 and anti-4-1BB vHHs. Both tumor efficacy and safety assessment were tested in human knockin mice.ResultsThe 4-1BB binder of PM1003 was found to interact with the CRD4 domain of 4-1BB, as determined by X-ray crystallography. Binding to this domain does not affect the binding between 4-1BB and its ligand 4-1BBL. The anti-PD-L1 vHH binds to an epitope on PD-L1 that overlaps with the binding region of PD-1, and is thus effective in disrupting the interaction between PD-1 and PD-L1. Using luciferase reporter assays and primary cell assays we found the PM1003 could activate 4-1BB in the context of PD-L1-mediated cross-bridging. Data from human 4-1BB and PD-L1 knockin mice also showed that PM1003 could effectively control tumor growth without observing any toxicity signals.ConclusionsPM1003 is a safe and efficacious bispecific antibody that blocks PD-L1 and concurrently activates 4-1BB receptor. An antibody with mild activity was selected directed against the CRD4 domain of 4-1BB to elicit effective potency while minimizing potential toxicity issues. This was reflected in our results. Thus, PM1003 is a potential next generation therapeutic antibody in the IO space that combines and synergizes two independent signaling pathways to control tumor growth.

The promise and perils of immunotherapy

Advances in understanding the ways in which the immune system fails to control tumor growth or prevent autoimmunity have led to the development of powerful therapeutic strategies to treat these diseases. In contrast to conventional therapies that have a broadly suppressive effect, immunotherapies are more akin to targeted therapies because they are mechanistically driven and are typically developed with the goal of “drugging” a specific underlying pathway or phenotype. This means that their effects and toxicities are, at least in theory, more straightforward to anticipate. The development of functionalized antibodies, genetically engineered T cells, and immune checkpoint inhibitors continues to accelerate, illuminating new biology and bringing new treatment to patients. In the following sections, we provide an overview of immunotherapeutic concepts, highlight recent advances in the field of immunotherapies, and discuss controversies and future directions, particularly as these pertain to hematologic oncology or blood-related diseases. We conclude by illustrating how original research published in this journal fits into and contributes to the overall framework of advances in immunotherapy.

The Combination of Radiotherapy With Immunotherapy and Potential Predictive Biomarkers for Treatment of Non-Small Cell Lung Cancer Patients

Radiotherapy is an effective local treatment modality of NSCLC. Its capabilities of eliminating tumor cells by inducing double strand DNA (dsDNA) damage and modulating anti-tumor immune response in irradiated and nonirradiated sites have been elucidated. The novel ICIs therapy has brought hope to patients resistant to traditional treatment methods, including radiotherapy. The integration of radiotherapy with immunotherapy has shown improved efficacy to control tumor progression and prolong survival in NSCLC. In this context, biomarkers that help choose the most effective treatment modality for individuals and avoid unnecessary toxicities caused by ineffective treatment are urgently needed. This article summarized the effects of radiation in the tumor immune microenvironment and the mechanisms involved. Outcomes of multiple clinical trials investigating immuno-radiotherapy were also discussed here. Furthermore, we outlined the emerging biomarkers for the efficacy of PD-1/PD-L1 blockades and radiation therapy and discussed their predictive value in NSCLC.