Enhanced Tumor Cell Killing Research Articles

ATP-Charged Nanoclusters Enable Intracellular Protein Delivery and Activity Modulation for Cancer Theranostics.

SummaryProtein drugs own a large share in the market and hold great prospects for the treatment of many diseases. However, the available protein drugs are limited to the extracellular target, owing to the inefficient transduction and activity modulation of proteins targeting intracellular environment. In this study, we constructed ATP-charged platforms to overcome the above-mentioned barriers for cancer theranostics. The phenylboronic acid-modified polycations (PCD) were synthesized to assemble with enzymes and shield its activity in the blood circulation. When the PCD nanoclusters reached tumor site, they effectively transported the enzymes into the cells, followed by recovering its catalytic activity after being charged with ATP. Importantly, the cascaded enzyme systems (GOx&HRPA) selectively induced starvation therapy as well as photoacoustic imaging of tumor. Our results revealed that the intelligent nanoclusters were broadly applicable for protein transduction and enzyme activity modulation, which could accelerate the clinical translation of protein drugs toward intracellular target.

Breast cancer stem cell RNA-pulsed dendritic cells enhance tumor cell killing by effector T cells.

Cancer stem cells (CSCs) underpin the resistance of breast cancer (BC) cells to therapy. Dendritic cell (DC)-based treatment is efficacious and safe, but the efficiency of this technique for targeting CSCs in BC treatment requires further investigation. The present study aimed to investigate the ability of DCs pulsed with breast CSC antigens to activate effector lymphocytes for killing BC cells. CD44+/CD24− CSCs were isolated from BCA55-121, an in-house patient-derived BC cell line, and acquisition of stemness properties was confirmed by upregulated expression of OCT4A and a superior proliferative capacity in colony formation assays compared with whole population of BCA55-121 (BCA55-121-WP). DCs were differentiated from monocytes from peripheral blood of healthy donors and pulsed with CSC total RNA. Maturation of the CSC RNA-pulsed DCs was confirmed by increased expression of CD11c, CD40, CD83, CD86 and HLA-DR, as well as reduced CD14 expression compared with monocytes. Total lymphocytes co-cultured with CSC RNA-pulsed DCs were analyzed by flow cytometry for markers including CD3, CD4, CD8, CD16 and CD56. The results revealed that the co-cultures contained mostly cytotoxic CD8+ T lymphocytes followed by CD4+ T lymphocytes and smaller populations of natural killer (NK) and NKT cells. ELISA was used to measure IFN-γ production, and it was revealed that activated CD4+ and CD8+ lymphocytes produced more IFN-γ compared with naïve T cells, suggesting that CD8+ T cells were effector T cells. CSC RNA was a more efficient antigen source compared with RNA from mixed BC cells for activating tumor antigen-specific killing by T cells. These CSC-specific effector T cells significantly induced BC cell apoptosis at a 20:1 effector T cell:tumor cell ratio. Of note, the breast CSCs cultures demonstrated resistance to effector T cell killing, which was in part due to increased expression of programmed death ligand 1 in the CSC population. The present study highlights the potential use of CSC RNA for priming DCs in modulating an anticancer immune response against BC.

Dual Inhibition of MCL1 and BCL2 in Lymphoma Using Tumor Targeted Nanoparticles

Cancer and normal cell utilize multiple members of the anti-apoptotic BCL2 proteins to protect them from cell death. Selective targeting of the BCL2 protein has a limited therapeutic value in the majority of cancer patients, including lymphoma, mainly due to the ability of cancer cells to utilize other members of the BCL2 family that are functionally redundant. While therapeutic targeting of multiple proteins will enhance tumor cell killing, such strategies will also lead to increased toxicity of vital organs. Here, we examined the single agent activity of the novel MCL1 inhibitor S63845 in a panel of lymphoma cell lines representing different cell of origin and differentiation states. Cell lines that were sensitive to S63845 expressed lower levels of BCL2. Consequently, we demonstrated that dual inhibition of BCL2 and MCL1, using the small molecule inhibitors Venetoclax and S63845, can lead to sustained and durable remissions of upto 250 days in mice harboring human DLBCL tumors after only 10 treatments (100 mg/kg Venetoclax oral and 25 mg/kg S63845 iv 5x/week). Monotherapy with S63845 or Venetoclax had a modest effect on tumor volume (41% and 36% tumor volume decrease upon S63845 or Venetoclax monotherapy, respectively). Immunohistochemistry of tumors from different treatment groups revealed that treatment with each drug alone resulted in minimal cleavage of caspase 3. In contrast, the combination of Venetoclax and S63845 resulted in diffuse caspase 3 cleavage, and cleavage of the caspase 3 target Poly (ADP-ribose) polymerase (PARP), indicative of apoptosis. However, unlike single agent therapy, combination treatment was also associated with significant weight loss of more than 15% pretreatment body weight, and hematological toxicity manifested in platelets, RBCs, WBCs and hemoglobin. Reduced dosing regimens induced complete remissions of tumors in mice but these were not durable, as tumor regrowth was observed around day 75 (~50 days after treatment cessation). To reduce the toxicity, we encapsulated either S63845 or Venetoclax into tumor targeted nanoparticles. Targeting of the drug loaded nanoparticle to the tumor is achieved by fucoidan, a fucosylated polysaccharide with nanomolar affinity to P-selectin, an inflammatory marker that is enriched in tumor sites. Fucoidan-decorated nanoparticles were synthesized by coencapsulating S63845 and a near infrared fluorophore IR783 that enables imaging. In vivo and ex vivo imaging studies demonstrated preferential targeting of the nanoparticles to the lymphoma while sparing vital organs, including the liver, heart, and kidneys (5 to 8-fold enrichment in the tumor). When MCL1 or BCL2 inhibitors were encapsulated into lymphoma-targeting nanoparticles we could lower the administered dose of these drugs by 3.5 and 6.5-fold, respectively. Combining either a nanoparticle encapsulated S63845 or Venetoclax with the other drug systemically administered induced durable remissions. When combination therapy was administered with one drug encapsulated as a nanoparticle, we did not observe significant weight loss or hematological toxicity, demonstrating that this nanoparticle delivery platform can deliver therapeutic drug concentration to tumor cells while sparing normal cells from treatment toxicity. This is the first study to demonstrate the potential therapeutic value of targeted BH3 mimetics nanoparticles in lymphoma. Disclosures Heller: Goldilocks Therapeutics Inc.: Equity Ownership, Other: Cofounder; Lipidsense Inc.: Other: Cofounder; Concarlo Holdings LLC: Consultancy. Younes:Merck: Honoraria, Research Funding; Takeda: Honoraria; Pharmacyclics: Research Funding; AstraZeneca: Research Funding; Genentech: Research Funding; Biopath: Consultancy; Xynomics: Consultancy; Epizyme: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; HCM: Consultancy; BMS: Research Funding; Syndax: Research Funding; Abbvie: Honoraria; Roche: Consultancy, Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Curis: Honoraria, Research Funding.

Population Pharmacokinetics and Novel Exposure-Response Analyses to Inform Optimal Biologic Dose Selection for CD20-TCB, a T-Cell-Engaging Bispecific Antibody, in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma

Population Pharmacokinetics and Novel Exposure-Response Analyses to Inform Optimal Biologic Dose Selection for CD20-TCB, a T-Cell-Engaging Bispecific Antibody, in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma

CD20-TCB, a Novel T-Cell-Engaging Bispecific Antibody, Can be Safely Combined with the Anti-PD-L1 Antibody Atezolizumab in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma

CD20-TCB, a Novel T-Cell-Engaging Bispecific Antibody, Can be Safely Combined with the Anti-PD-L1 Antibody Atezolizumab in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma

CD20-TCB, a Novel T-Cell-Engaging Bispecific Antibody, Induces T-Cell-Mediated Killing in Relapsed or Refractory Non-Hodgkin Lymphoma: Biomarker Results From a Phase I Dose-Escalation Trial

Introduction: CD20-TCB (RG6026) is a novel T-cell-engaging bispecific (TCB) antibody with a '2:1' molecular format that comprises two fragment antigen binding regions that bind CD20 (on the surface of B cells) and one that binds CD3 (on the surface of T cells). CD20-TCB offers the potential for increased tumor antigen avidity, rapid T-cell activation, and enhanced tumor cell killing versus other bispecific formats. The safety, tolerability, pharmacokinetics, biomarkers, and antitumor activity of CD20-TCB are currently being investigated in a multicenter Phase I dose-escalation trial (NP30179; NCT03075696). We recently presented preliminary clinical data demonstrating promising clinical activity in relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) patients with indolent or aggressive disease (Dickinson et al. ICML 2019). Here, we present preliminary blood and tissue biomarker analyses to explore modes of action, support optimal biological dose selection, and identify potential outcome predictors. Methods: For biomarker analyses, we performed immune profiling of peripheral blood by flow cytometry, analyzed plasma cytokine levels by ELISA, and characterized baseline and on-treatment tumor biopsies by immunohistochemistry/immunofluorescence assays and RNA sequencing. Biomarker data were obtained from 122 patients dosed with 0.005-25mg CD20-TCB. Results: CD20-TCB infusion led to a rapid and transient reduction in T cells in the peripheral circulation (T-cell margination) in all patients. T-cell margination reached nadir 6 hours after the first CD20-TCB infusion, and showed a strong association with CD20-TCB dose and receptor occupancy (RO%; as determined by Djebli et al. ASH 2019). Interestingly, rebound of T cells 160 hours after the first CD20-TCB infusion was associated with response to treatment. Responding patients showed long-term T-cell activation after the first infusion of CD20-TCB at doses from 0.6mg and above. T-cell activation was demonstrated by 2-4-fold elevation of T-cell activation markers such as Ki67, HLA-DR, PD-1, ICOS, OX40, and 4-1BB, which was sustained up to Cycle 5 (105 days). Analysis of paired pre- and on-treatment tumor biopsies (n=6) obtained before and 2-3 weeks after the first dose of CD20-TCB showed evidence of T-cell-mediated tumor cell killing. Analysis of archival and pre-treatment tumor biopsies (n=80) revealed that clinical responses were achieved irrespective of the amount of tumor T-cell infiltration at baseline. In contrast, preliminary baseline bulk tumor RNA sequencing data (n=46) showed upregulation of gene signatures associated with cell proliferation/Myc and T-cell subsets (effector vs exhausted-like) in non-responding patients. Conclusions: In this study, we demonstrated the mode of action of CD20-TCB, a novel bispecific antibody with promising clinical activity in R/R NHL. We also demonstrated that biomarker data on T-cell activation can support dose finding in conjunction with pharmacokinetics. Additional analysis is ongoing to evaluate response predictors and better characterize the population that will benefit most from T-cell mediated therapies. Disclosures Bröske: Roche: Employment, Equity Ownership. James:A4P Consulting Ltd: Consultancy. Belousov:Roche: Employment. Gomez:F. Hoffmann-La Roche Ltd: Employment. Canamero:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Ooi:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Grabole:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Wilson:F. Hoffmann-La Roche Ltd: Employment. Korfi:F. Hoffmann-La Roche Ltd: Consultancy. Kratochwil:F. Hoffmann-La Roche Ltd: Employment. Morcos:Roche: Employment, Equity Ownership. Ferlini:Roche: Employment, Equity Ownership. Thomas:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Dimier:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Moore:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Bacac:Roche: Employment, Equity Ownership, Patents & Royalties: Patents, including the one on CD20-TCB. Weisser:Pharma Research and Early Development Roche Innovation Center Munich: Employment, Equity Ownership, Patents & Royalties. Dickinson:Merck Sharpe and Dohme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. OffLabel Disclosure: CD20-TCB (also known as RG6026, RO7082859) is a full-length, fully humanized, immunoglobulin G1 (IgG1), T-cell-engaging bispecific antibody with two fragment antigen binding (Fab) regions that bind to CD20 (on the surface of B cells) and one that binds to CD3 (on the surface of T cells) (2:1 format). The 2:1 molecular format of CD20-TCB, which incorporates bivalent binding to CD20 on B cells and monovalent binding to CD3 on T cells, redirects endogenous non-specific T cells to engage and eliminate malignant B cells. CD20-TCB is an investigational agent.

Dual CD20-Targeted Therapy With Concurrent CD20-TCB and Obinutuzumab Shows Highly Promising Clinical Activity and Manageable Safety in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma: Preliminary Results From a Phase Ib Trial

Dual CD20-Targeted Therapy With Concurrent CD20-TCB and Obinutuzumab Shows Highly Promising Clinical Activity and Manageable Safety in Relapsed or Refractory B-Cell Non-Hodgkin Lymphoma: Preliminary Results From a Phase Ib Trial

CD171- and GD2-specific CAR-T cells potently target retinoblastoma cells in preclinical in vitro testing

BackgroundChimeric antigen receptor (CAR)-based T cell therapy is in early clinical trials to target the neuroectodermal tumor, neuroblastoma. No preclinical or clinical efficacy data are available for retinoblastoma to date. Whereas unilateral intraocular retinoblastoma is cured by enucleation of the eye, infiltration of the optic nerve indicates potential diffuse scattering and tumor spread leading to a major therapeutic challenge. CAR-T cell therapy could improve the currently limited therapeutic strategies for metastasized retinoblastoma by simultaneously killing both primary tumor and metastasizing malignant cells and by reducing chemotherapy-related late effects.MethodsCD171 and GD2 expression was flow cytometrically analyzed in 11 retinoblastoma cell lines. CD171 expression and T cell infiltration (CD3+) was immunohistochemically assessed in retrospectively collected primary retinoblastomas. The efficacy of CAR-T cells targeting the CD171 and GD2 tumor-associated antigens was preclinically tested against three antigen-expressing retinoblastoma cell lines. CAR-T cell activation and exhaustion were assessed by cytokine release assays and flow cytometric detection of cell surface markers, and killing ability was assessed in cytotoxic assays. CAR constructs harboring different extracellular spacer lengths (short/long) and intracellular co-stimulatory domains (CD28/4-1BB) were compared to select the most potent constructs.ResultsAll retinoblastoma cell lines investigated expressed CD171 and GD2. CD171 was expressed in 15/30 primary retinoblastomas. Retinoblastoma cell encounter strongly activated both CD171-specific and GD2-specific CAR-T cells. Targeting either CD171 or GD2 effectively killed all retinoblastoma cell lines examined. Similar activation and killing ability for either target was achieved by all CAR constructs irrespective of the length of the extracellular spacers and the co-stimulatory domain. Cell lines differentially lost tumor antigen expression upon CAR-T cell encounter, with CD171 being completely lost by all tested cell lines and GD2 further down-regulated in cell lines expressing low GD2 levels before CAR-T cell challenge. Alternating the CAR-T cell target in sequential challenges enhanced retinoblastoma cell killing.ConclusionBoth CD171 and GD2 are effective targets on human retinoblastoma cell lines, and CAR-T cell therapy is highly effective against retinoblastoma in vitro. Targeting of two different antigens by sequential CAR-T cell applications enhanced tumor cell killing and preempted tumor antigen loss in preclinical testing.

Enhancing the anti‐tumor efficacy of chimeric antigen receptor‐expressing T cells with naturally occurring plant stilbenes

Despite advances in treatment options, cancer remains the second leading cause of death in the United States. Many therapies use immune cells, specifically T cells, for cancer therapy. To enhance tumor recognition by T cells, chimeric antigen receptors consisting of signaling domains fused to receptors that recognize tumor antigens can be created and expressed in T cells. One receptor that is a prospective target for a chimeric antigen receptor is PD1 because the ligands for the PD1 receptor are expressed on many cancer types. Our lab has genetically engineered a chimeric PD1 (chPD1) receptor and has shown that chPD1‐expressing T cells kill tumor cells, secrete inflammatory cytokines, reduce tumor burden, and increase survival in multiple tumor types. A current focus of cancer research is the development of combination therapies that enhance anti‐tumor efficacy without increasing harmful side effects. Recently, a family of naturally occurring plant compounds called stilbenes have been shown to enhance T cell function. Therefore, we tested if stilbenes enhanced chPD1 T cell function in breast cancer. Addition of resveratrol, a stilbene found in berries, grapes, peanuts, and other plants, decreased proliferation, enhanced tumor cell killing, and increased secretion of proinflammatory cytokines (IFNγ, GM‐CSF, TNFα, IL‐17, IL‐2, and IL‐21) from chPD1 T cells. Presence of resveratrol also increased skewing of T cell differentiation to a central memory phenotype through reduction of AKT and mTORc1 signaling, reduced expression of T‐bet and BLIMP‐1 transcription factors, and increased expression of Bcl‐6 and Eomes transcription factors. Hence, combination of resveratrol and chimeric antigen receptor‐expressing T cells may enhance anti‐tumor immune responses through inhibition of the AKT and mTORc1 pathways and skewing to a long‐lived central memory phenotype.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Study on the Size Dependence of AuNPs in Enhancement Radiation Effect for Superficial Kilovoltage X-Rays

Radiation therapy and chemotherapy remain the most widely used treatment options in treating cancer. Recent developments in cancer research show that therapy combined with high-atomic number materials such as gold nanoparticles (AuNPs) is a new way to treat cancer, in which AuNPs are injected through intravenous administration and bound to tumor sites has enhanced tumor cell killing. Radiation therapy aims to deliver a high therapeutic dose of ionizing radiation to the tumor without exceeding normal tissue tolerance. In this work AuNPs have been used for the enhancement of radiation effects on breast cancer cells (MCF-7) for superficial kilovoltage X-ray radiation therapy. The use of AuNPs in superficial kilovoltage X-ray beams radiation therapy will provide a high probability for photon interaction by photoelectric effect. These provide advantages in terms of radiation dose enhancement. In this work, MCF-7 cells were seeded in the 96-well plate and treated with 13 nm, 50 nm and 70 nm AuNPs before they were irradiated with 80 kVp X-rays beam at various radiation doses. Photoelectric effect is the dominant process of interaction of 80 kVp X-rays with AuNPs. When the AuNPs are internalized into the MCF-7 cells, the dose enhancement effect is observed. The presence of AuNPs in the MCF-7 cells will produce a higher number of photoelectrons, and resulting more “free radicals” that will lead to increase in cell death. Then, these free radicals will lead to DNA damage to the MCF-7 cells. To validate the enhanced killing effect, both with and without AuNPs MCF-7 cells is irradiated simultaneously. By comparison, the results show that AuNPs significantly enhance cancer killing and the enhancement radiation effect was dependent on the size of AuNPs.

Combination of cabazitaxel and p53 gene therapy abolishes prostate carcinoma tumor growth.

For patients with metastatic prostate cancer, the 5-year survival rate of 31% points to a need for novel therapies and improvement of existing modalities. We propose that p53 gene therapy and chemotherapy, when combined, will provide superior tumor cell killing for the treatment of prostate carcinoma. To this end, we have developed the AdRGD-PGp53 vector which offers autoregulated expression of p53, resulting in enhanced tumor cell killing in vitro and in vivo. Here, we combined AdRGD-PGp53 along with the chemotherapy drugs used in the clinical treatment of prostate carcinoma, mitoxantrone, docetaxel, or cabazitaxel. Our results indicate that all drugs increase phosphorylation of p53, leading to improved induction of p53 targets. In vitro experiments reveal that AdRGD-PGp53 sensitizes prostate cancer cells to each of the drugs tested, conferring increased levels of cell death. In a xenograft mouse model of in situ gene therapy, AdRGD-PGp53 treatment, when combined with cabazitaxel, drastically reduced tumor progression and increased survival rates to 100%. Strikingly, we used a sub-therapeutic dose of cabazitaxel thus avoiding leukopenia, yet still showed potent anti-tumor effects when combined with AdRGD-PGp53 in this mouse model. The AdRGD-PGp53 approach warrants further development for its application in gene therapy of prostate carcinoma.

CD20-Tcb (RG6026), a Novel “2:1” Format T-Cell-Engaging Bispecific Antibody, Induces Complete Remissions in Relapsed/Refractory B-Cell Non-Hodgkin's Lymphoma: Preliminary Results from a Phase I First in Human Trial

CD20-Tcb (RG6026), a Novel “2:1” Format T-Cell-Engaging Bispecific Antibody, Induces Complete Remissions in Relapsed/Refractory B-Cell Non-Hodgkin's Lymphoma: Preliminary Results from a Phase I First in Human Trial

Natural Killer Cell Dysfunction in Hepatocellular Carcinoma: Pathogenesis and Clinical Implications.

Hepatocellular carcinoma (HCC) is currently the third leading cause of malignancy-related mortalities worldwide. Natural killer (NK) cells are involved in the critical role of first line immunological defense against cancer development. Defects in NK cell functions are recognized as important mechanisms for immune evasion of tumor cells. NK cell function appears to be attenuated in HCC, and many previous reports suggested that NK cells play a critical role in controlling HCC, suggesting that boosting the activity of dysfunctional NK cells can enhance tumor cell killing. However, the detailed mechanisms of NK cell dysfunction in tumor microenvironment of HCC remain largely unknown. A better understanding of the mechanisms of NK cell dysfunction in HCC will help in the NK cell-mediated eradication of cancer cells and prolong patient survival. In this review, we describe the various mechanisms underlying human NK cell dysfunction in HCC. Further, we summarize current advances in the approaches to enhance endogenous NK cell function and in adoptive NK cell therapies, to cure this difficult-to-treat cancer.

Regulation of innate and adaptive antitumor immunity by IAP antagonists.

Inhibition of the T-cell co-inhibitory checkpoint receptors or their ligands CTLA-4, PD-1 and PD-L1 using monoclonal antibodies has proven to be highly effective against many cancers. Yet many cancers remain resistant to checkpoint blockade, and durable remissions occur in only a minority of patients. Novel approaches to enhancing antitumor responses are thus necessary in order to expand the reach of these treatments. The inhibitor of apoptosis (IAP) protein family comprises a diverse group of proteins, many of which have immunoregulatory roles. Small molecule IAP antagonists have been developed and are undergoing early phase clinical testing. These drugs were initially developed to promote tumor cell apoptosis; however, a considerable body of work now indicates that IAP antagonists induce antitumor activity through modulation of innate and adaptive immunity. Primarily through inhibition of cellular (c)-IAP1 and c-IAP2, IAP antagonists can activate alternative NF-κB signaling, promoting B-cell survival, activation of dendritic cells and delivering a broad co-stimulatory signal to T cells. At the same time, IAP antagonists can promote tumor cell intrinsic sensitization to innate immune signals, and enhance tumor cell killing by inflammatory cytokines and phagocytic macrophages. These drugs thus represent an attractive investigational approach to immunotherapy, providing a positive signaling counterpart to the relief of signal inhibition conferred by checkpoint blockade.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

A DHODH inhibitor increases p53 synthesis and enhances tumor cell killing by p53 degradation blockage

The development of non-genotoxic therapies that activate wild-type p53 in tumors is of great interest since the discovery of p53 as a tumor suppressor. Here we report the identification of over 100 small-molecules activating p53 in cells. We elucidate the mechanism of action of a chiral tetrahydroindazole (HZ00), and through target deconvolution, we deduce that its active enantiomer (R)-HZ00, inhibits dihydroorotate dehydrogenase (DHODH). The chiral specificity of HZ05, a more potent analog, is revealed by the crystal structure of the (R)-HZ05/DHODH complex. Twelve other DHODH inhibitor chemotypes are detailed among the p53 activators, which identifies DHODH as a frequent target for structurally diverse compounds. We observe that HZ compounds accumulate cancer cells in S-phase, increase p53 synthesis, and synergize with an inhibitor of p53 degradation to reduce tumor growth in vivo. We, therefore, propose a strategy to promote cancer cell killing by p53 instead of its reversible cell cycle arresting effect.

Folate-modified PLGA nanoparticles for tumor-targeted delivery of pheophorbide a in vivo

Targeted drug delivery has been an important issue for tumor therapy including photodynamic therapy (PDT). The purpose of our study is to increase the targeting efficiency of photosensitizer (PS) using folate-modified nanoparticles (NPs) to tumor site in vivo. Folate receptor is over-expressed on the surface of many human cancer cells. We prepared poly (lactic-co-glycolic acid) (PLGA) NPs containing pheophorbide a (Pba), a PS that is used in PDT and generates free radical for killing cancer cells. The surface of NPs was composed of phospholipids modified with polyethylene glycol (PEG) and folate (FA). The size of the resulting FA-PLGA-Pba NPs was about 200 nm in PBS at pH 7.4 and they were stable for long time. They showed faster cellular uptake to MKN28 human gastric cancer cell line than control PLGA-Pba NPs by high-affinity binding with folate receptors on cell surface. In MTT assay, FA-PLGA-Pba NPs also showed enhanced tumor cell killing compared to control PLGA-Pba NPs. In vivo and ex vivo imaging showed high accumulation of FA-PLGA-Pba NPs in tumor site during 24 h after intravenous injection to MKN28 tumor-bearing mice model. These results demonstrate that our FA-PLGA-Pba NPs are useful for tumor-targeted delivery of PS for cancer treatment by PDT.

PD-L1 checkpoint inhibition and anti-CTLA-4 whole tumor cell vaccination counter adaptive immune resistance: A mouse neuroblastoma model that mimics human disease.

BackgroundAdaptive immune resistance induces an immunosuppressive tumor environment that enables immune evasion. This phenomenon results in tumor escape with progression and metastasis. Programmed cell death-ligand 1 (PD-L1) expressed on tumors is thought to inhibit tumor-infiltrating lymphocytes (TILs) through programmed cell death 1 (PD1), enabling adaptive immune resistance. This study investigates the role of PD-L1 in both mouse and human neuroblastoma immunity. The consequence of PD-L1 inhibition is characterized in the context of an established whole tumor cell vaccine.Methods and findingsA mouse model of neuroblastoma was investigated using an Id2 knockdown whole cell vaccine in combination with checkpoint inhibition. We show that immunogenic mouse neuroblastoma acquires adaptive immune resistance by up-regulating PD-L1 expression, whereas PD-L1 is of lesser consequence in nonimmunogenic neuroblastoma tumors. Combining PD-L1 checkpoint inhibition with whole tumor cell/anti-CTLA-4 vaccination enhanced tumor cell killing, cured mice with established tumors, and induced long-term immune memory (6 months). From an evaluation of patient neuroblastoma tumors, we found that the inflammatory environment of the mouse neuroblastoma mimicked human disease in which PD-L1 expression was associated directly with TILs and lower-risk tumors. High-risk patient tumors were lacking both TILs and PD-L1 expression. Although a correlation in immunity seems to exist between the mouse model and human findings, the mouse tumor model is induced and not spontaneously occurring, and furthermore, the number of both mouse and human correlates is limited.ConclusionsThis study demonstrates the role PD-L1 plays in neuroblastoma’s resistance to immunity and defines the nonredundant effect of combination checkpoint inhibition with vaccine therapy in a mouse model. High-risk, nonimmunogenic human tumors display both diminished PD-L1 expression and adaptive immune resistance. Paradoxically, high-risk tumors may be more responsive to effective vaccine therapy because of their apparent lack of adaptive immune resistance.

Combining ultrasound and intratumoral administration of doxorubicin-loaded microspheres to enhance tumor cell killing

Melanoma is an incurable disease for which alternative treatments to chemotherapy alone are sought. Here, using a melanoma model, we investigated the antitumor potential of combining ultrasound (US) with poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with doxorubicin (DOX). The aim was to achieve synergistic tumoricidal activity through direct and indirect US-mediated damage of tumor cells combined with sustained and potentially controllable release (when combined with US) of DOX from microspheres. An in vitro release assay demonstrated an ability of US to affect the release kinetics of DOX from DOX-loaded PLGA microspheres by inducing a 12% increase in the rate of release. In vitro viability assays demonstrated that combining US with DOX-loaded PLGA microspheres resulted in synergistic tumor cell (B16-F10 melanoma cells) killing. Melanoma-bearing mice were treated intratumorally with DOX (8 µg)-loaded microspheres and subjected to US treatment at the tumor site. This treatment could significantly extend survival (mean survival (MS) = 22.1 days) compared to untreated mice (MS = 10.4 days) and most other treatments, such as blank microspheres plus US (MS = 11.5 days) and DOX (8 µg)-loaded microspheres alone (MS = 13 days). The findings that immune checkpoint blockade did not significantly extend survival of mice treated with DOX (8 µg)-loaded microspheres plus US, and that tumor-free (“cured”) mice were not protected from subsequent tumor rechallenge suggests minimal involvement of the adaptive immune response in the observed antitumor activity. Nevertheless, the synergistic increase in survival of melanoma-challenged mice treated with the combination of US and DOX-loaded microspheres implicates such a treatment methodology as a promising additional tool for combatting otherwise currently incurable cancers.

Photoimmunotherapy by Cortactin monoclonal antibody conjugated with Hematoporphyrin derivative of a subcutaneous murine mammary adenocarcinoma using low power He-Ne laser

Photoimmunotherapy (PIT) is a promising approach which aims to increase the specificity of photosensitisers used in photodynamic therapy through its conjugation to monoclonal antibodies (MAb) directed against tumour antigens. The current study aims to increase and improve the therapeutic selectivity of photodynamic therapy (PDT) by conjugating the HpD to specific (mAb) in order to target one of the specific antigens of mammary adenocarcinoma. a screening has been done to detect specific antigens on mammary adenocarcinoma cells and we found that Cortactin is the unique antigen on tumor tissue in our model, then anti-cortactin mAb was linked to HPD, used for not only improve specificity, but vastly enhances tumor cell killing when they are photo-immunotargeted by HpD-monoclonal antibody conjugates comparing with unconjugated HPD and then exposed to low power He-Ne laser (632 nm). Female mice, which were transplanted with AM3 (mouse mammary adenocarcinoma transplantable tumor line), were randomly divided into five groups of 10 mice each; the first group was treated by PIT using HpD conjugated with Cortactin, in comparison with HpD alone in a second group. The third and fourth were control groups with and without HpD alone respectively. Tumor growth indices and metastasis incidence were calculated. Photoimmunotargeting by HpD-mAb conjugates activated by a low-power He-Ne laser showed significant tumor growth inhibition similar to PDT using unconjugated HpD activated by He-Ne laser, whilst control groups were without any significant effect. The resultssuggest that conjugation was with low quantity of the HPD or not stable enough and this need further studies.