Early Detection of Myeloid-Derived Suppressor Cells in the Lung Pre-Metastatic Niche by Shortwave Infrared Nanoprobes

Metastatic breast cancer remains a significant source of mortality amongst breast cancer patients and is generally considered incurable in part due to the difficulty in detection of early micro-metastases. The pre-metastatic niche (PMN) is a tissue microenvironment that has undergone changes to support the colonization and growth of circulating tumor cells, a key component of which is the myeloid-derived suppressor cell (MDSC). Therefore, the MDSC has been identified as a potential biomarker for PMN formation, the detection of which would enable clinicians to proactively treat metastases. However, there is currently no technology capable of the in situ detection of MDSCs available in the clinic. Here, we propose the use of shortwave infrared-emitting nanoprobes for the tracking of MDSCs and identification of the PMN. Our rare-earth albumin nanocomposites (ReANCs) are engineered to bind the Gr-1 surface marker of murine MDSCs. When delivered intravenously in murine models of breast cancer with high rates of metastasis, the targeted ReANCs demonstrated an increase in localization to the lungs in comparison to control ReANCs. However, no difference was seen in the model with slower rates of metastasis. This highlights the potential utility of MDSC-targeted nanoprobes to assess PMN development and prognosticate disease progression.

Integrated metabolic and genetic analysis reveals distinct features of human differentiated thyroid cancer

BACKGROUND

Differentiated thyroid cancer (DTC) affects thousands of lives worldwide each year. Typically, DTC is a treatable disease with a good prognosis. Yet, some patients are subjected to partial or total thyroidectomy and radioiodine therapy to prevent local disease recurrence and metastasis. Unfortunately, thyroidectomy and/or radioiodine therapy often worsen(s) quality of life and might be unnecessary in indolent DTC cases. On the other hand, the lack of biomarkers indicating a potential metastatic thyroid cancer imposes an additional challenge to managing and treating patients with this disease.

AIM

The presented clinical setting highlights the unmet need for a precise molecular diagnosis of DTC and potential metastatic disease, which should dictate appropriate therapy.

MATERIALS AND METHODS

In this article, we present a differential multi-omics model approach, including metabolomics, genomics, and bioinformatic models, to distinguish normal glands from thyroid tumours. Additionally, we are proposing biomarkers that could indicate potential metastatic diseases in papillary thyroid cancer (PTC), a sub-class of DTC.

RESULTS

Normal and tumour thyroid tissue from DTC patients had a distinct yet well-defined metabolic profile with high levels of anabolic metabolites and/or other metabolites associated with the energy maintenance of tumour cells. The consistency of the DTC metabolic profile allowed us to build a bioinformatic classification model capable of clearly distinguishing normal from tumor thyroid tissues, which might help diagnose thyroid cancer. Moreover, based on PTC patient samples, our data suggest that elevated nuclear and mitochondrial DNA mutational burden, intra-tumour heterogeneity, shortened telomere length, and altered metabolic profile reflect the potential for metastatic disease.

DISCUSSION

Altogether, this work indicates that a differential and integrated multi-omics approach might improve DTC management, perhaps preventing unnecessary thyroid gland removal and/or radioiodine therapy.

CONCLUSIONS

Well-designed, prospective translational clinical trials will ultimately show the value of this integrated multi-omics approach and early diagnosis of DTC and potential metastatic PTC.

Integrated metabolic and genetic analysis reveals distinct features of primary differentiated thyroid cancer and its metastatic potential in humans

Differentiated thyroid cancer (DTC) affects thousands of lives worldwide every year. Typically, DTC is a treatable disease with a good prognosis. Yet, some patients are subjected to partial or total thyroidectomy and radioiodine therapy to prevent local disease recurrence and metastasis. Unfortunately, thyroidectomy and/or radioiodine therapy often worsen(s) the quality of life and might be unnecessary in indolent DTC cases. This clinical setting highlights the unmet need for a precise molecular diagnosis of DTC, which should dictate appropriate therapy. Here we propose a differential multi-omics model approach to distinguish normal gland from thyroid tumor and to indicate potential metastatic diseases in papillary thyroid cancer (PTC), a sub-class of DTC. Based on PTC patient samples, our data suggest that elevated nuclear and mitochondrial DNA mutational burden, intratumor heterogeneity, shortened telomere length, and altered metabolic profile reflect the potential for metastatic disease. Specifically, normal and tumor thyroid tissues from these patients had a distinct yet well-defined metabolic profile with high levels of anabolic metabolites and/or other metabolites associated with the energy maintenance of tumor cells. Altogether, this work indicates that a differential and integrated multi-omics approach might improve DTC management, perhaps preventing unnecessary thyroid gland removal and/or radioiodine therapy. Well-designed, prospective translational clinical trials will ultimately show the value of this targeted molecular approach.

TRANSLATIONAL RELEVANCE

In this article, we propose a new integrated metabolic, genomic, and cytopathologic methods to diagnose Differentiated Thyroid Cancer when the conventional methods failed. Moreover, we suggest metabolic and genomic markers to help predict high-risk Papillary Thyroid Cancer. Both might be important tools to avoid unnecessary surgery and/or radioiodine therapy that can worsen the quality of life of the patients more than living with an indolent Thyroid nodule.

Autophagy Regulates Stress Responses, Metabolism, and Anticancer Immunity

Autophagy is a catabolic intracellular nutrient-scavenging pathway triggered by nutrient deprivation and stress that captures and degrades intracellular proteins and organelles in lysosomes. The breakdown products are then recycled into metabolic pathways to sustain survival. Organelle turnover by autophagy contributes to quality control and suppresses inflammation. Autophagy is upregulated in many cancers and supports their growth, survival, and malignancy in a tumor cell-autonomous fashion. Host autophagy also promotes tumor growth by maintaining a supply of essential nutrients and suppressing innate and adaptive antitumor immune responses. Autophagy is also upregulated in response to cancer therapy and confers treatment resistance. Thus, autophagy is a cancer vulnerability and its inhibition is under investigation as a novel therapeutic approach.

Design and proof of concept for targeted phage-based COVID-19 vaccination strategies with a streamlined cold-free supply chain

Development of effective vaccines against coronavirus disease 2019 (COVID-19) is a global imperative. Rapid immunization of the entire human population against a widespread, continually evolving, and highly pathogenic virus is an unprecedented challenge, and different vaccine approaches are being pursued. Engineered filamentous bacteriophage (phage) particles have unique potential in vaccine development due to their inherent immunogenicity, genetic plasticity, stability, cost-effectiveness for large-scale production, and proven safety profile in humans. Herein we report the development and initial evaluation of two targeted phage-based vaccination approaches against SARS-CoV-2: dual ligand peptide-targeted phage and adeno-associated virus/phage (AAVP) particles. For peptide-targeted phage, we performed structure-guided antigen design to select six solvent-exposed epitopes of the SARS-CoV-2 spike (S) protein. One of these epitopes displayed on the major capsid protein pVIII of phage induced a specific and sustained humoral response when injected in mice. These phage were further engineered to simultaneously display the peptide CAKSMGDIVC on the minor capsid protein pIII to enable their transport from the lung epithelium into the systemic circulation. Aerosolization of these "dual-display" phage into the lungs of mice generated a systemic and specific antibody response. In the second approach, targeted AAVP particles were engineered to deliver the entire S protein gene under the control of a constitutive CMV promoter. This induced tissue-specific transgene expression, stimulating a systemic S protein-specific antibody response in mice. With these proof-of-concept preclinical experiments, we show that both targeted phage- and AAVP-based particles serve as robust yet versatile platforms that can promptly yield COVID-19 vaccine prototypes for translational development.

Abstract 2802: Rare earth albumin nanoparticles engineered to target cytotoxic T cells to evaluate response to immunotherapy

Checkpoint immunotherapy, through the reversal of tumor-mediated inactivation of the immune system, has shown promise in the treatment of several types of cancer. This has culminated in the approval of seven immune checkpoint inhibitors (ICIs). However, only a small population of patients respond to these drugs. Because of the physical and economic burden of ICIs on the patient, there is a critical need to identify biomarkers that can inform on the potential response to ICIs. The presence of tumor infiltrating lymphocytes (TILs) has demonstrated good prognostic value in determining if a patient should receive ICIs. Current clinical methods to assess TILs involve invasive biopsies and immunohistochemistry, which suffer from intratumoral heterogeneity, observer variability, and a lack of real-time feedback. Here, we report on near infrared light excitable rare earth metal-based nanoparticles, termed rare earth albumin nanocomposites (ReANCs), that emit shortwave infrared (SWIR) light, allowing for deep tissue imaging and high signal-to-noise ratios compared to visible or near infrared fluorescence probes. Tumor-targeted ReANCs have been previously employed to monitor tumor progression and response to chemotherapy in mouse models of breast cancer metastasis. In this study, to target CD3+ T cells, ReANCs were conjugated using the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) to a peptide derived from the sequence of the CD3-ϵ receptor sub-unit. Target specific binding was validated by flow cytometry as a measure of increased uptake of peptide-conjugated ReANCs by Jurkat cells. To specifically target cytotoxic T lymphocytes, we employed the fragment antigen binding (Fab) derived from enzymatic digestion of a CD8 antibody (clone 53-6.7) with papain. The Fab fragments were conjugated to ReANCs with sulfo-succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (sulfo-SMCC). Conjugation was confirmed by non-reducing gel electrophoresis and high performance liquid chromatography (HPLC). A loading efficiency of approximately 60% was achieved. Target specific binding was validated by flow cytometry as a measure of increased uptake of Fab-conjugated ReANCs by T cells isolated from splenocytes. We generated a metric for measuring immune burden around tumor spheroids by pre-labeling T cells with ReANCs and co-culturing them with tumor cell spheroids in vitro. Imaging of T cells with CD3 and CD8-targeted ReANCs provides a basis for future in vivo small animal imaging studies where we will investigate the potential of this technology to track immune cells in relation to a tumor in real time. Metrics of immune cell imaging will then inform on the potential of immunotherapy and monitor response to treatment in a longitudinal study.

Citation Format: Jay V. Shah, Jake N. Siebert, Amber Gonda, Rahul Pemmaraju, Shashank Kosuri, Carolina Bobadilla Mendez, Xinyu Zhao, Shuqing He, Richard E. Riman, Mei Chee Tan, Mark C. Pierce, Edmund C. Lattime, Prabhas V. Moghe, Vidya Ganapathy. Rare earth albumin nanoparticles engineered to target cytotoxic T cells to evaluate response to immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2802.

Design and proof-of-concept for targeted phage-based COVID-19 vaccination strategies with a streamlined cold-free supply chain

Development of effective vaccines against Coronavirus Disease 2019 (COVID-19) is a global imperative. Rapid immunization of the world human population against a widespread, continually evolving, and highly pathogenic virus is an unprecedented challenge, and many different vaccine approaches are being pursued to meet this task. Engineered filamentous bacteriophage (phage) have unique potential in vaccine development due to their inherent immunogenicity, genetic plasticity, stability, cost-effectiveness for large-scale production, and proven safety profile in humans. Herein we report the design, development, and initial evaluation of targeted phage-based vaccination approaches against Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) by using dual ligand peptide-targeted phage and adeno-associated virus/phage (AAVP) particles. Towards a unique phage- and AAVP-based dual-display candidate approach, we first performed structure-guided antigen design to select six solvent-exposed epitopes of the SARS-CoV-2 spike (S) protein for display on the recombinant major capsid coat protein pVIII. Targeted phage particles carrying one of these epitopes induced a strong and specific humoral response. In an initial experimental approach, when these targeted phage particles were further genetically engineered to simultaneously display a ligand peptide (CAKSMGDIVC) on the minor capsid protein pIII, which enables receptor-mediated transport of phage particles from the lung epithelium into the systemic circulation (termed "dual-display"), they enhanced a systemic and specific spike (S) protein-specific antibody response upon aerosolization into the lungs of mice. In a second line of investigation, we engineered targeted AAVP particles to deliver the entire S protein gene under the control of a constitutive cytomegalovirus (CMV) promoter, which induced tissue-specific transgene expression stimulating a systemic S protein-specific antibody response. As proof-of-concept preclinical experiments, we show that targeted phage- and AAVP-based particles serve as robust yet versatile enabling platforms for ligand-directed immunization and promptly yield COVID-19 vaccine prototypes for further translational development.

SIGNIFICANCE

The ongoing COVID-19 global pandemic has accounted for over 2.5 million deaths and an unprecedented impact on the health of mankind worldwide. Over the past several months, while a few COVID-19 vaccines have received Emergency Use Authorization and are currently being administered to the entire human population, the demand for prompt global immunization has created enormous logistical challenges--including but not limited to supply, access, and distribution--that justify and reinforce the research for additional strategic alternatives. Phage are viruses that only infect bacteria and have been safely administered to humans as antibiotics for decades. As experimental proof-of-concept, we demonstrated that aerosol pulmonary vaccination with lung-targeted phage particles that display short epitopes of the S protein on the capsid as well as preclinical vaccination with targeted AAVP particles carrying the S protein gene elicit a systemic and specific immune response against SARS-CoV-2 in immunocompetent mice. Given that targeted phage- and AAVP-based viral particles are sturdy yet simple to genetically engineer, cost-effective for rapid large-scale production in clinical grade, and relatively stable at room temperature, such unique attributes might perhaps become additional tools towards COVID-19 vaccine design and development for immediate and future unmet needs.

B7 immune-checkpoints as targets for the treatment of neuroendocrine tumors

The B7 family, and their receptors, the CD28 family, are major immune checkpoints that regulate T-cell activation and function. In the present study, we explore the role of two B7 immune-checkpoints: HERV-H LTR-Associating Protein 2 (HHLA2) and B7 Family Member, H4 (B7x), in the progression of gastrointestinal and pancreatic neuroendocrine tumors (GINETs and PNETs). We demonstrated that both HHLA2 and B7x were expressed to a high degree in human GINETs and PNETs. We determined that the expression of B7x and HHLA2 correlates with higher grade and higher incidence of nodal and distant spread. Furthermore, we confirmed that HIF-1α overexpression is associated with the upregulation of B7x both in our in vivo (animal model) and in vitro (cell culture) models. When grown in vitro, islet tumor β-cells lack B7x expression, unless cultured under hypoxic conditions, which results in both hypoxia-inducible factor 1 subunit alpha (HIF-1α) and B7x upregulation. In vivo, we demonstrated that Men1/B7x double knockout (KO) mice (with loss of B7x expression) exhibited decreased islet β-cell proliferation and tumor transformation accompanied by increased T-cell infiltration compared with Men1 single knockout mice. We have also shown that systemic administration of a B7x mAb to our Men1 KO mice with PNETs promotes an antitumor response mediated by increased T-cell infiltration. These findings suggest that B7x may be a critical mediator of tumor immunity in the tumor microenvironment of NETs. Therefore, targeting B7x offers an attractive strategy for the immunotherapy of patients suffering from NETs.

Targeting tumor-associated macrophages to combat pancreatic cancer

The tumor microenvironment is replete with cells that evolve with and provide support to tumor cells during the transition to malignancy. The hijacking of the immune system in the pancreatic tumor microenvironment is suggested to contribute to the failure to date to produce significant improvements in pancreatic cancer survival by various chemotherapeutics. Regulatory T cells, myeloid derived suppressor cells, and fibroblasts, all of which constitute a complex ecology microenvironment, can suppress CD8+ T cells and NK cells, thus inhibiting effector immune responses. Tumor-associated macrophages (TAM) are versatile immune cells that can express different functional programs in response to stimuli in tumor microenvironment at different stages of pancreatic cancer development. TAM have been implicated in suppression of anti-tumorigenic immune responses, promotion of cancer cell proliferation, stimulation of tumor angiogenesis and extracellular matrix breakdown, and subsequent enhancement of tumor invasion and metastasis. Many emerging agents that have demonstrated efficacy in combating other types of tumors via modulation of macrophages in tumor microenvironments are, however, only marginally studied for pancreatic cancer prevention and treatment. A better understanding of the paradoxical roles of TAM in pancreatic cancer may pave the way to novel preventive and therapeutic approaches. Here we give an overview of the recruitment and differentiation of macrophages, TAM and pancreatic cancer progression and prognosis, as well as the potential preventive and therapeutic targets that interact with TAM for pancreatic cancer prevention and treatment.

Non-oncogenic Acute Viral Infections Disrupt Anti-cancer Responses and Lead to Accelerated Cancer-Specific Host Death

In light of increased cancer prevalence and cancer-specific deaths in patients with infections, we investigated whether infections alter anti-tumor immune responses. We report that acute influenza infection of the lung promotes distal melanoma growth in the dermis and leads to accelerated cancer-specific host death. Furthermore, we show that during influenza infection, anti-melanoma CD8⁺ T cells are shunted from the tumor to the infection site, where they express high levels of the inhibitory receptor programmed cell death protein 1 (PD-1). Immunotherapy to block PD-1 reverses this loss of anti-tumor CD8⁺ T cells from the tumor and decreases infection-induced tumor growth. Our findings show that acute non-oncogenic infection can promote cancer growth, raising concerns regarding acute viral illness sequelae. They also suggest an unexpected role for PD-1 blockade in cancer immunotherapy and provide insight into the immune response when faced with concomitant challenges.

Abstract B100: Panvac-F and Panvac-V: Phase I study of intratumoral and systemic vaccination

Patients with adenocarcinoma of the pancreas were treated using a combination of EUS-guided intrapancreatic tumor injection and systemic boost using PANVAC-F and PANVAC-V in this first-in-man Phase I trial. The study represents the translation of our unique demonstration in murine models of bladder and orthotopic mammary tumors that anergy to systemic immunization using antigen encoding vaccinia recombinants could be overcome by immunization into the tumor microenvironment. Consented patients with locally advanced or minimally metastatic pancreatic cancer received EUS-guided intrapancreatic injections (IT) of recombinant Panvac-F (Fowlpox encoding MUC-1, CEA, TRICOM), systemic subcutaneous (SC) Panvac-V (vaccinia) and SC Panvac-F boosts. Systemic SC vaccines were accompanied by subcutaneous rH-GM-CSF, 100 mcg X 4 days. Patients received 2 intrapancreatic injections of Panvac-F (2 weeks apart) with systemic Panvac-V and Panvac-F boosts given with GMCSF extending to day 71 (total of 2 IT Panvac-F, 1 SC Panvac-V, 4 SC Panvac-F). Patients were allowed to transition to standard care at day 31. Patients were evaluated for toxicity and tumor progression. Follow-up care was provided by referring oncologists. In this dose escalation study, the first cohort of 6 pts received IT Panvac-F (10 8 PFU), SC Panvac-V (2 X 10 8 PFU), and SC Panvac-F (10 9 PFU). The second dose cohort of 8 pts received IT Panvac-F (10 9 PFU), SC Panvac-V (2 X 10 8 PFU), and SC Panvac-F (10 9 PFU ). At dose level 1, two of six patients were removed from study after approximately two weeks due to rapid disease progression and died one and six months after trial initiation. At dose level 2, one patient was removed due to rapidly progressive disease and died at 1 mo and a second patient withdrew following 1 IT inoculation and died at month 16. Of the remaining 10 pts, 3 presented with distant metastatic disease (Median Survival 7 mos, range 1-25) and 7 presented without distant metastases (Median Survival 16 mos, range 3-35). Of note, none of the 7 patients presenting without metastatic disease developed distant visceral metastases, by imaging available to us but died of sequellae associated with progressive local disease. Of the above 10 pts, all but one transitioned initially to treatment with gemcitabine-based therapy. (the remaining pt did not begin systemic treatment). Initial RNAseq transcriptome analysis of Fine Needle Aspirate (FNA) comparing Day 1 and Day 14 samples demonstrated a significant increase in a series of chemokines associated with the induction of an immune response in the tumor microenvironment. A planned series of immunologic and genetic analyses are underway. Results demonstrate that the “first in man” intrapancreatic administration of recombinant poxvirus was well tolerated with the complete regimen suggesting an encouraging period of stable disease. The finding that none of the patients who presented without distant visceral metastases developed such would be consistent with the generation of a systemic immune response with effects on seeded metastatic cells. Analysis of local and systemic immune responses is currently proceeding and may provide further insights. This study is supported by the NCI Cancer Therapeutics Evaluation Program (CTEP) and by NCI U01-CA07031 and P30-CA72720.

Citation Format: Elizabeth A. Poplin, David A. August, Rebecca A. Moss, Tamir Ben-Menachem, Hazar Michael, Aparna Repaka, Renee Artymyshyn, Chang Chan, James L. Gulley, Robert S. DiPaola, Edmund C. Lattime. Panvac-F and Panvac-V: Phase I study of intratumoral and systemic vaccination. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B100.

The addition of recombinant vaccinia HER2/neu to oncolytic vaccinia-GMCSF given into the tumor microenvironment overcomes MDSC-mediated immune escape and systemic anergy

Effective immunotherapeutic strategies require the ability to generate a systemic antigen-specific response capable of impacting both primary and metastatic disease. We have built on our oncolytic vaccinia a granulocyte-macrophage colony-stimulating factor (GM-CSF) strategy by adding recombinant tumor antigen to increase the response in the tumor microenvironment and systemically. In the present study, orthotopic growth of a syngeneic HER2/neu-overexpressing mammary carcinoma in FVB/N mice (NBT1) was associated with increased Gr1(+)CD11b(+) myeloid-derived suppressor cells (MDSCs) both systemically and in the tumor microenvironment. This MDSC population had inhibitory effects on the HER2/neu-specific Th1 immune response. VVneu and VVGMCSF are recombinant oncolytic vaccinia viruses that encode HER2/neu and GM-CSF, respectively. Naive FVB mice vaccinated with combined VVneu and VVGMCSF given systemically developed systemic HER2/neu-specific immunity. NBT1-bearing mice became anergic to systemic immunization with combined VVneu and VVGMCSF. Intratumoral VVGMCSF failed to result in systemic antitumor immunity until combined with intratumoral VVneu. Infection/transfection of the tumor microenvironment with combined VVGMCSF and VVneu resulted in development of systemic tumor-specific immunity, reduction in splenic and tumor MDSC and therapeutic efficacy against tumors. These studies demonstrate the enhanced efficacy of oncolytic vaccinia virus recombinants encoding combined tumor antigen and GM-CSF in modulating the microenvironment of MDSC-rich tumors.

Cellular Autophagy Machinery is not Required for Vaccinia Virus Replication and Maturation

The origin of the primary membrane of the vaccinia virus, a double-membrane structure that surrounds the immature virions (IV), is not fully understood. Here we investigated whether the primary membrane originates from the autophagic membrane. Morphologic studies by electron microscopy (EM) showed no apparent difference in viral maturation in the autophagy-deficient cell lines, the atg5(-/-) mouse embryonic fibroblasts (MEFs) and the beclin1(-/-) embryonic stem (ES) cells, compared to their isogenic wild-type counterparts. Moreover, viral growth curves demonstrated that vaccinia viruses replicate and mature in the autophagy-deficient cell lines as efficiently as they do in their isogenic wild type counterpart cells. This study indicates that the cellular autophagy machinery is not required for the life-cycle of vaccinia virus, suggesting that the primary vaccinia viral membrane does not originate from the autophagic membrane.

PLGA-polymer encapsulating tumor antigen and CpG DNA administered into the tumor microenvironment elicits a systemic antigen-specific IFN-γ response and enhances survival

Critical to the generation of an effective therapeutic antitumor immune response is the elicitation of effective antigen presentation coupled with overcoming tumor-immune escape mechanisms. Towards this end, we aimed to understand the therapeutic effectiveness of a polymer based vaccine approach at enhancing the anti-tumor responses in a tumor-bearing mouse model. While we and others have previously demonstrated the effectiveness of PLGA based systems in delivering antigen etc., studies scarcely focus on understanding the immunological mechanisms of polymer based therapies in tumor bearing treatment models. Considering tumors modulate the immune system and consequently the efficacy of therapies, understanding treatment mechanisms in the presence of tumor will help lead to more efficacious treatment options. We demonstrate here that a poly(lactic-co-glycolic acid) (PLGA) based delivery system encapsulating tumor antigen (OVA) and the TLR9 agonist CpG motif DNA administered into the tumor microenvironment initiates an effective type 1 mediated (IFN-γ producing) anti-tumor response in a syngeneic murine model of T cell lymphoma (E.G7-OVA). Although E.G7-OVA tumors spontaneously generate antigen specific CTLs in draining lymph nodes (LN), tumors progress rapidly. Modulation of the tumor microenvironment via local PLGA based therapy led to the generation of a systemic antigen specific Th1 response, absent in the non-polymer delivery method, subsequently associated with reduced tumor growth and prolongation of survival. These studies provide further insight into the use of a PLGA-based therapeutic approach at modulating the tumor microenvironment and highlight the need for analyzing the treatment effects in a tumor bearing model.

Vaccinia virus leads to ATG12–ATG3 conjugation and deficiency in autophagosome formation

The interactions between viruses and cellular autophagy have been widely reported. On the one hand, autophagy is an important innate immune response against viral infection. On the other hand, some viruses exploit the autophagy pathway for their survival and proliferation in host cells. Vaccinia virus is a member of the family of Poxviridae which includes the smallpox virus. The biogenesis of vaccinia envelopes, including the core envelope of the immature virus (IV), is not fully understood. In this study we investigated the possible interaction between vaccinia virus and the autophagy membrane biogenesis machinery. Massive LC3 lipidation was observed in mouse fibroblast cells upon vaccinia virus infection. Surprisingly, the vaccinia virus induced LC3 lipidation was shown to be independent of ATG5 and ATG7, as the atg5 and atg7 null mouse embryonic fibroblasts (MEFs) exhibited the same high levels of LC3 lipidation as compared with the wild-type MEFs. Mass spectrometry and immunoblotting analyses revealed that the viral infection led to the direct conjugation of ATG3, which is the E2-like enzyme required for LC3-phosphoethanonamine conjugation, to ATG12, which is a component of the E3-like ATG12–ATG5-ATG16 complex for LC3 lipidation. Consistently, ATG3 was shown to be required for the vaccinia virus induced LC3 lipidation. Strikingly, despite the high levels of LC3 lipidation, subsequent electron microscopy showed that vaccinia virus-infected cells were devoid of autophagosomes, either in normal growth medium or upon serum and amino acid deprivation. In addition, no autophagy flux was observed in virus-infected cells. We further demonstrated that neither ATG3 nor LC3 lipidation is crucial for viral membrane biogenesis or viral proliferation and infection. Together, these results indicated that vaccinia virus does not exploit the cellular autophagic membrane biogenesis machinery for their viral membrane production. Moreover, this study demonstrated that vaccinia virus instead actively disrupts the cellular autophagy through a novel molecular mechanism that is associated with aberrant LC3 lipidation and a direct conjugation between ATG12 and ATG3.

Abstract 5378: Phase I trial of EUS-guided intratumoral vaccination with recombinant Panvac-F and systemic Panvac-V in patients with locally advanced pancreatic cancer

Preclinical studies in our laboratory were the first to demonstrate the superiority of intratumoral poxvirus vaccines in overcoming immune escape and effectively treating murine solid tumor models. Murine models of bladder and orthotopic mammary tumor demonstrated anergy to systemic immunization using antigen encoding vaccinia recombinants while responding to immunization into the tumor microenvironment. We present here the translation of these findings to a Phase I trial in six patients with locally advanced inoperable adenocarcinoma of the pancreas (NCT00669734). The first dose cohort of patients were treated using a combination of EUS-guided intrapancreatic tumor injection of recombinant Panvac-F (Fowlpox encoding MUC-1, CEA, TRICOM, 108 PFU) in addition to systemic Panvac-V (vaccinia, 2 X 108 PFU) and Panvac-F (109 PFU) boosts (accompanied by subcutaneous rH-GM-CSF, 100 mcg X 4 days). Patients received a total of 2 intrapancreatic injections of Panvac-F (2 weeks apart) with systemic Panvac-V and Panvac-F boosts given with GMCSF extending to day 71 (total of 2 intrapancreatic Panvac-F, 1 sc Panvac-V, 4 sc Panvac-F). Patients were allowed to transition to standard care at day 35. Patients were evaluated for toxicity, tumor progression, and serum CA 19-9 and CEA levels. Two of six patients were removed from study after approximately two weeks due to rapid disease progression and died one and six months after trial initiation. Of the remaining four, one had received prior treatment with gemcitabine followed by capecitabine and radiation and received no further treatment after vaccination; three received post-vaccination standard treatment with gemcitabine. Of the 4 patients with followup of greater than 6 mos, all have stable disease with no progression to metastasis (19 mos, 17 mos, 16 mos, 13 mos). One pt had a DLT (pancreatitis) that resolved allowing completion of protocol therapy. Results demonstrate that the “first in human” intrapancreatic administration of recombinant poxvirus was well tolerated with the complete regimen suggesting an encouraging period of stable disease. The trial is currently accruing patients at intrapancreatic dose level 2 (109 PFU). This study is supported by the NCI Cancer Therapeutics Evaluation Program (CTEP) and by NCI U01-CA07031 and P30-CA72720.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5378. doi:1538-7445.AM2012-5378

Abstract C241: Phase I trial of EUS-guided intratumoral vaccination with recombinant Panvac-F and systemic Panvac-V in patients with locally advanced pancreatic cancer

Preclinical studies in our laboratory were the first to demonstrate the superiority of intratumoral poxvirus vaccines in overcoming immune escape and effectively treating murine solid tumor models. We present here the translation of these findings to a Phase I trial in six patients with locally advanced inoperable adenocarcinoma of the pancreas (NCT00669734). The first dose cohort of patients were treated using a combination of EUS (Endoscopic Ultrasound)-guided intrapancreatic tumor injection of recombinant Panvac-F (Fowlpox encoding MUC-1, CEA, TRICOM, 108 PFU) in addition to systemic Panvac-V (vaccinia, 2 × 108 PFU) and Panvac-F (109 PFU) boosts (accompanied by subcutaneous rH-GM-CSF, 100 mcg × 4 days). Patients received a total of 2 intrapancreatic injections of Panvac-F (2 weeks apart) with systemic Panvac-V and Panvac-F boosts given with GMCSF extending to day 71 (total of 2 intrapancreatic Panvac-F, 1 sc Panvac-V, 4 sc Panvac-F). Patients were allowed to transition to standard care at day 31. Patients were evaluated for toxicity, tumor progression, and serum CA 19–9 and CEA levels. Two of six patients were removed from study after approximately two weeks due to rapid disease progression and died one and six months after trial initiation. Of the remaining four, one had received prior treatment with gemcitabine followed by capecitabine and radiation and received no further treatment after vaccination; three received post-vaccination standard treatment with gemcitabine. Of the 4 patients with followup of greater than 6 mos, all have clinically stable disease (15 mos, 13 mos, 12 mos, 9 mos). One pt had a DLT (pancreatitis) that resolved allowing completion of protocol therapy. Results demonstrate that the “first in human” intrapancreatic administration of the full recombinant poxvirus regimen was well tolerated with encouraging stable disease duration. The trial is currently accruing patients at intrapancreatic dose level 2 (109 PFU).

This study is supported by the NCI Cancer Therapy Evaluation Program (CTEP) and by NCI U01-CA07031 and P30-CA72720.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C241.

Antineoplastic Effects of Partially HLA-Matched Irradiated Blood Mononuclear Cells in Patients With Renal Cell Carcinoma

Purpose: Vaccines, cytokines, and other biologic-based therapies are being developed as antineoplastic agents. Many of these agents are designed to induce an autologous immune response directed against the malignancy. In contrast, hematopoietic stem-cell transplantation is being developed as a form of allogeneic immunotherapy. This study tests the tolerance and antineoplastic activity of sequential infusions of partially HLA-matched allogeneic blood mononuclear cells (obtained from relatives) when administered outside of the context of a hematopoietic stem-cell transplantation. The cells are irradiated to prevent graft-versus-host disease.

Patients and Methods: Fifteen patients with relapsed or refractory malignancies for which no standard therapy was available were enrolled onto a clinical trial designed to assess the tolerability and antineoplastic effects of irradiated partially HLA-matched blood mononuclear cells obtained from relatives.

Results: There was disease regression in three patients with metastatic renal cell carcinoma during treatment. There was disease progression in six patients with metastatic renal cell carcinoma and two patients with metastatic melanoma during treatment. There was no change in disease state in several other patients.

Conclusion: Irradiated allogeneic blood mononuclear cells administered outside the context of hematopoietic stem-cell transplantation may induce disease responses in patients with relapsed or refractory malignancies. Transfusion of irradiated allogeneic blood mononuclear cells should be developed further as a novel therapeutic antineoplastic approach.

Intratumoral vaccination with vaccinia-expressed tumor antigen and granulocyte macrophage colony-stimulating factor overcomes immunological ignorance to tumor antigen

Using a murine transitional cell carcinoma tumor model, MB49, which naturally expresses the male antigen HY, we evaluated whether tumor ignorance as determined by lack of a systemic immune response could be overcome by immunization with vaccinia expressed tumor antigen and granulocyte macrophage colony-stimulating factor. Systemic tumor ignorance of MB49 was demonstrated by the lack of a splenic HY-specific CTL response in MB49-bearing female mice. In contrast, we demonstrated HY-specific CTL priming in the draining lymph nodes. MB49-bearing female B6 mice were immunized with VVHY+VVGMCSF intratumorally or in the contralateral flank. Intratumoral VVHY, VVGMCSF, and keyhole limpet hemocyanin (to produce CD4 help) generated splenic HY-specific CD8 CTLs, whereas immunization with the combination in the contralateral flank or single agents given intratumorally failed to yield a splenic response. Purified male T cells injected intratumorally, as a source of HY antigen, also generated a HY-specific response, whereas contralateral immunizations did not. These finding expand the understanding of tumor immunological ignorance and support intratumoral vaccination as a strategy for immunotherapy of established tumors.

Tumor-induced interleukin 10 suppresses the ability of splenic dendritic cells to stimulate CD4 and CD8 T-cell responses

Dendritic cell (DC) maturation and function are influenced by the surrounding cytokine milieu. We demonstrate tumor-associated suppression of DCs in stimulating allogeneic and tumor-specific CTL and type 1 (IFN-gamma-producing) responses in both CD4- and CD8-positive T cells. DCs from MB49-bearing female mice fail to stimulate proliferative and IFN-gamma-producing responses in allogeneic mixed lymphocyte cultures. MB49 also inhibited DC function in stimulating type 1 responses against our tumor-specific antigen, the male antigen, HY. DCs from MB49-bearing male mice were unable to restimulate effective HY-specific CTLs or IFN-gamma. Tumor-induced interleukin (IL) 10 was found to be specifically responsible for DC dysfunction in response to antigenic driven maturation. This was demonstrated by restoration of DC function in splenic DCs from MB49-bearing female IL-10 knockout mice (HY disparity), whereas not in MB49-bearing male IL-10 knockout mice (no HY disparity). Finally, any tumor-induced systemic inhibitory effect on bone marrow precursors could be overcome by generation of bone marrow-derived DCs ex vivo. These bone marrow-derived DCs derived from MB49-bearing B6 mice were capable of inducing control levels of proliferation in allogeneic mixed lymphocyte reactions and a type 1 (IFN-gamma) cytokine profile. The BM-DCs were also capable of restimulating HY-specific CTL and IFN-gamma production. These studies reveal the tumor-associated in vivo effects of IL-10 inhibition on DC function in eliciting a type 1 immune response in both allogeneic and tumor-specific responses.

Virotherapy clinical trials for regional disease: in situ immune modulation using recombinant poxvirus vectors

The ability of viruses to readily infect tumor cells both in vitro and in vivo has resulted in their study as antitumor agents through a variety of strategies. Replicating and conditionally replicating viruses and recombinant viruses encoding genes for toxins and/or prodrugs have been studied for their direct antitumor activity with promising results. However, to date, the lack of a targettable construct able to localize to all tumors following systemic administration has proven to be a major limitation in their use for metastatic disease. The ability of a variety of well-characterized viruses to serve as vectors for expression of tumor antigens and/or cytokines has also resulted in their study as immunotherapeutic agents. In this review, we discuss preclinical and clinical data that support the use of recombinant poxviruses as vectors for in situ tumor transfection with immune-enhancing cytokines and immune costimulatory antigens. We hypothesize that such an approach will ultimately lead to enhanced immune recognition of tumor and the development of an effective systemic antitumor immune response capable of eradicating primary and metastatic tumor foci.

Phase i study of intravesical vaccinia virus as a vector for gene therapy of bladder cancer

PURPOSE

Vaccinia virus is a DNA poxvirus previously used as a vaccine to eradicate smallpox. The virus has a high efficiency of infection, replicates in the cytoplasm without chromosomal integration and can transport a large amount of recombinant DNA without losing infectivity. Therefore, it is an excellent choice as a vector for gene delivery in vivo. Large quantities of vaccinia have been injected into dermal, subcutaneous and peripheral lymph node melanoma metastases without significant side effects, and with efficient infection of the tumor cells and recombinant gene transfection. To determine if vaccinia, when given intravesically, can effectively infect bladder mucosa and tumor with acceptable toxicity, we performed a phase I trial of intravesical vaccinia in patients with muscle invasive transitional cell carcinoma before radical cystectomy.

MATERIALS AND METHODS

After documenting immune competence and demonstration of a major reaction after revaccination, patients received 3 increasing doses of intravesical Dryvax vaccinia virus (Wyeth-Ayerst Laboratories, Philadelphia, Pennsylvania) that was provided by the Centers for Disease Control. Approximately 24 hours after the third dose, cystectomy was performed and the tissue was examined microscopically.

RESULTS

There were 4 patients who were treated. The 3 patients who received the highest doses (100 x 106 plaque forming units) had significant mucosal and submucosal inflammatory infiltration by lymphocytes, eosinophils, and plasma cells into tumor and normal tissue. Dendritic cells were recruited to the site after exposure to the vaccinia. Significant mucosal edema and vascular ectasia were seen. Tumor and normal urothelial cells showed evidence of viral infection, including enlarged vacuolated cells with cytoplasmic inclusions. There were no clinical or laboratory manifestations of vaccinia related toxicity except mild dysuria. Of the 4 patients 3 survived and were free of disease at 4-year followup.

CONCLUSIONS

Our study demonstrates that vaccinia virus can be administered safely into the bladder with recruitment of lymphocytes and induction of a brisk local inflammatory response. To our knowledge, this is the first report of direct delivery of live virus into the human bladder. The role of wild type vaccinia as immunotherapy for bladder cancer warrants further study. Furthermore, these data support the exploration of recombinant vaccinia as a putative gene therapy vector for intravesical infection and transfection of bladder tumor cells with cytokine or other genes, an approach that our group pioneered and most recently studied in patients with superficial melanoma.

Intratumoral recombinant GM-CSF-encoding virus as gene therapy in patients with cutaneous melanoma

Seven immunocompetent, revaccinated patients with surgically incurable cutaneous melanoma underwent treatment of dermal and/or subcutaneous metastases with twice-weekly intratumoral injections of escalating doses (10(4)-2 x 10(7) plaque-forming units (PFU)/lesion; 10(4)-8 x 10(7) PFU/session) of a vaccinia/GM-CSF recombinant virus for 6 weeks. Patients with stable or responding disease were maintained on treatment until tumor resolution or progression. Systemic toxicity was infrequent, dose-related, and limited to mild flu-like symptoms that resolved within 24 hours. Local inflammation, at times with pustule formation, was consistently seen with doses of > or =10(7) PFU/lesion. Chronically treated lesions showed a dense infiltration, with CD4+ and CD8+ lymphocytes, histiocytes, and eosinophils. All seven patients developed an antivaccinia humoral immune response 14-21 days following revaccination. Despite the presence of these antivaccinia antibodies, the reporter gene was expressed, as judged by the development of anti-beta-galactosidase antibodies in all patients. Passenger cytokine gene function was evidenced by the presence of virally encoded GM-CSF mRNA at injection sites both early (weeks 1 and 5) and late (week 31) in the course of treatment. Eosinophilia at treatment sites indicated that physiologically significant levels of functional cytokine were generated. However, there were no changes in the total number of peripheral white blood cells or in the numbers or percentages of polymorphonuclear leukocytes, monocytes, or eosinophils. GM-CSF was not detected in the sera. The two patients with the largest tumor burdens failed to respond even at treatment sites. Three patients had mixed responses, with regression of treated and untreated dermal metastases and progression of disease elsewhere. One patient had a partial response, with regression of injected and uninjected regional dermal metastases. Residual melanoma was excised, rendering the patient disease free. One patient with only dermal metastases confined to the scalp achieved a complete remission. Sequential administration of escalating doses of a GM-CSF recombinant vaccinia virus is safe, effective at maintaining passenger gene function, and can induce tumor regression.

Tumor-induced interleukin-10 inhibits type 1 immune responses directed at a tumor antigen as well as a non-tumor antigen present at the tumor site

Interleukin (IL)-10 is a potent immunosuppressive cytokine that has been found to be present at the tumor site in a wide variety of human cancers, including transitional cell carcinoma of the bladder. Using a murine bladder tumor (MB49), which we show to express the male transplantation antigen (HY), we tested the hypothesis that IL-10 at the tumor site can block the generation of a tumor-specific type 1 immune response. We show that, despite its expression of HY, MB49 fails to prime for an HY-specific type 1 (IFN-gamma) response in normal female mice. Although MB49 does not constitutively produce IL-10, our data support a model whereby MB49 induces infiltrating cells to produce IL-10. This feature rendered the IL-10 knockout (KO) mouse, whose infiltrating cells are incapable of IL-10 production, a suitable model in which to study MB49 in the absence of IL-10. When injected into IL-10 KO mice, MB49 does prime for an HY-specific, type 1 immune response. Furthermore, IL-10 KO mice show prolonged survival and an increased capacity to reject tumors as compared with normal mice. We also tested the ability of tumor-induced IL-10 to inhibit immunization to a non-tumor antigen present at the tumor site. When vaccinia virus encoding beta-galactosidase (beta-gal) is injected into the tumors of normal mice, no beta-gal-specific IFN-gamma response is mounted. However, when this same viral construct is injected into the tumors of IL-10 KO mice, it produces a strong beta-gal-specific, IFN-gamma response. These studies demonstrate that tumor-induced IL-10 can block the generation of a tumor-specific type 1 immune response as well as subvert attempts to elicit a type 1 immune response to a non-tumor antigen at the tumor site.

Phase I study of R24 in patients with metastatic melanoma including evaluation of immunologic parameters

R24 is a mouse IgG3 monoclonal antibody with specificity for the disialoganglioside GD3. Most human melanomas have substantial surface GD3; in addition, a significant proportion of T lymphocytes display surface GD3. In a phase I study, we have investigated the toxicity and effect on selected immunological parameters of three dose levels of R24 given intravenously daily for five days (10 mg/m2/d, 30 mg/m2/d and 50 mg/m2/d) to patients with advanced melanoma. R24 administration neither consistently diminished nor augmented expression of delayed type hypersensitivity (DTH) skin reactions to anergy panel antigens or to a contact allergen dinitrofluorobenzene. R24 was infrequently found on tumor cells, or on lymphocytes from DTH biopsies, despite measurable serum levels of R24. The 30 mg/m2/d dose of R24 produced a statistically significant drop in peripheral blood lymphocytes on treatment Day 5. Likewise, on Day 5 there was a modest but statistically significant decrement in the proportion of circulating cells which were R24+. While there was one mixed response, there were no complete or partial tumor regressions in the R24 treated patients; there was no evident clinical benefit from the R24 therapy. The toxicity of the R24 at the higher dose levels can be very substantial. One patient, on the highest dose level, died on the 4th day of R24 treatment; in the absence of a plausible alternative explanation, a relationship of the death to the administered R24 must be considered. A precipitous drop in serum albumin coincident with R24 administration was found in all cases; this effect has not been previously reported with R24.

Neutralizing anti-IL-10 antibody upregulates the induction and elicitation of contact hypersensitivity

Various cytokines have been shown to modulate the acquisition and expression of delayed-type hypersensitivity. In a mouse model, we tested the notion that neutralization of interleukin-10 (IL-10), a cytokine that inhibits T cell-mediated reactions, would upregulate delayed-type hypersensitivity. We used two different monoclonal antibodies with specificity for murine IL-10 and used allergic contact dermatitis as a prototypical example of delayed-type hypersensitivity. When anti-IL-10 antibody was given at the time of sensitization to a contact allergen, there was a substantial increase in the induced contact hypersensitivity (CHS). In other experiments, the challenge reactions to contact allergen in routinely sensitized mice were increased when anti-IL-10 antibody was given at the time of challenge. Primary irritant reactions to croton oil were increased but only if anti-IL-10 antibody was given at the time of challenge and not when it was given a week previously. It appears that anti-IL-10 antibody can potentiate CHS reactivity by inactivating otherwise downregulating endogenous IL-10.

Interleukin 10 production by human melanoma

Interleukin 10 (IL-10) has the physiological role of down-regulating cell-mediated immunity. We have recently reported that mRNA for IL-10 was present in most metastatic melanoma tissues. The purpose of this investigation was to determine whether melanoma metastases produce IL-10 protein. Single-cell suspensions were prepared by enzymatic dissociation of 28 lymph node metastases and 7 s.c. metastases and cryopreserved. Of these 35 samples, 30 produced IL-10 after a 24-h incubation (median, 125.1 pg/ml). IL-10 production was slightly diminished after 25 Gy irradiation but almost completely abrogated after modification with the hapten dinitrophenyl. After 7 or 14 days in tissue culture, melanoma cells continued to produce IL-10 but only at about 10% of the levels of freshly dissociated tissues. Moreover, of eight melanoma cell lines established from these cultures, only one produced IL-10 protein. To determine whether IL-10 was produced by melanoma cells or tumor-associated leukocytes, single-cell suspensions were fractionated with anti-CD45 antibody-conjugated magnetic beads. In four of five samples, IL-10 production was increased by depletion of leukocytes, suggesting that the primary source was the melanoma cells themselves. This was confirmed by immunohistochemical staining of cytospin preparations and frozen tissue sections. Finally, 10 of 55 patients with clinically evident metastases showed elevations of circulating IL-10; three patients who had been melanoma-free developed high serum IL-10 levels, concurrent with the appearance of distant metastases. These data indicate that production of IL-10 is characteristic of metastatic melanomas and raise the possibility that this cytokine allows tumors to avoid or to modulate immunological attack.

Development of secondary structure, growth characteristics and cytogenetic analysis of human transitional cell carcinoma xenografts in scid/scid mice

PURPOSE

The growth of human bladder transitional cell carcinoma (TCC) in scid/scid mice was examined.

MATERIALS AND METHODS

Cystocopically obtained TCC biopsies were implanted in scid/scid mice, and successful xenografts were compared with original tumors for growth and genetic characteristics.

RESULTS

Low grade papillary tumors formed fluid-filled pseudobladders lined with malignant urothelium and papillary fronds containing fibrovascular cores recruited from the murine host. High grade xenografts grew without these secondary structures. When compared with the patient tumors, xenograft growth fractures, as measured by proliferating cell nuclear antigen, p53 expression and ploidy, were similar in each.

CONCLUSIONS

The scid/scid xenografts maintain phenotype and architecture. This model may be useful for studying factors determining tumor grade, angiogenesis and tissue organization.

In situ cytokine gene transfection using vaccinia virus vectors

Studies by a number of investigators have focused on inducing tumor-specific immunity as a therapeutic approach to cancer. Successful immunotherapeutic strategies have involved localized treatment with immune-active adjuvants, systemic administration using cytokines such as interleukin-2, and the use of whole tumor cells or tumor cell fragments as vaccines. With an increasing understanding of the requirements for the development of an immune response, immunotherapeutic strategies have focused on providing mechanistic requirements, such as tumor or accessory antigen expression and cytokine-based "immune help." Recent preclinical studies have shown that ex vivo cytokine gene transfection of tumor cells and their use as vaccines result in the enhanced development of antitumor immunity and in some cases can be used to successfully treat pre-existing tumors. Studies from our laboratory have explored the use of vaccinia virus recombinants to directly transfect tumor cells in situ with cytokine genes as a strategy for enhancing the development of antitumor immunity. We have demonstrated that vaccinia virus recombinants are highly efficient in transfecting a wide range of murine and human tumors in vitro and can be used with similar effects in in vivo murine models. In addition, we have found that vaccinia virus productively infects human melanoma cells following intratumoral injection in patients with accessible lesions. In situ transfection is highly efficient, and therapy with increasing doses of virus is safe with only minor side effects. The results of our studies support the use of cytokine-encoding recombinant vaccinia virus vectors for in situ transfection in patients with cancer.

Gene therapy for human cancer: an essay for clinicians

In the last decade our understanding of the processes that govern growth and differentiation has become quite sophisticated. A variety of tumor suppressor genes and more than 100 oncogenes have been identified. The roles of developmental genes in shaping the expression of neoplasia and of defective housekeeping genes in allowing mutations to persist and be transcribed have been appreciated. These advances have revolutionized our ability to diagnose and to formulate prognoses for patients with cancer. However, successful gene therapy for cancer has been elusive. This review highlights the current approaches to gene therapy for cancer and their scientific bases. The requirement that the therapy repair or destroy every cancer cell seems an insurmountable hurdle. Environmental manipulation through systemic administration of exogenous antisense may circumvent this problem in cases where it is appropriate. The more practical application of the technology of genetic engineering to facilitate cancer chemotherapy and immunotherapy is also reviewed. Particularly encouraging are the preclinical and clinical results of in vivo, in situ gene transfer. It remains to be determined if this local approach impacts favorably on survival.

Expression of cytokine mRNA in human melanoma tissues

We have reported that patients with metastatic melanoma treated with an autologous, dinitrophenol-modified vaccine develop inflammatory responses at tumor sites. Histologically, these inflamed lesions are characterized by T cell infiltration, which is sometimes associated with tumor cell destruction. We tested biopsy specimens of eight subcutaneous metastases that had developed inflammation following vaccine treatment for expression of mRNA for interferon gamma (IFN gamma), interleukin-4 (IL-4), tumor necrosis factor alpha (TNF alpha), and IL-10. Post-vaccine, inflamed biopsies contained mRNA for IFN gamma (5/8), IL-4 (4/8) or both (3/8), and for TNF alpha (4/7). In contrast, IFN gamma mRNA was detected in only 1/17 and TNF alpha mRNA in 2/16 control specimens (pre-treatment lymph node metastases or non-inflamed subcutaneous metastases). mRNA for IL-10, a cytokine with anti-inflammatory properties, was detected in 24/25 melanoma metastases and was independent of lymphoid content; in situ the reverse transcriptase/polymerase chain reaction confirmed that melanoma cells were the major source. These findings may provide a new parameter by which to measure the effects of cancer immunotherapy.

De novo decorin gene expression suppresses the malignant phenotype in human colon cancer cells

The rapid progress in the cloning of proteoglycan genes has enabled investigators to examine in depth the functional roles these polyhedric molecules play in the control of cell proliferation. Decorin, a leucine-rich proteoglycan expressed by most connective tissues, is a prototype molecule that regulates cellular growth via two mechanisms: modulation of growth factor activity and matrix assembly. We now provide direct evidence that human colon cancer cells stably transfected with decorin cDNA exhibit a marked suppression of the transformed phenotype: the cells have a reduced growth rate in vitro, form small colonies in soft agar, and do not generate tumors in scid/scid mice. Several independent clones are arrested in the G1 phase of the cell cycle, and their growth suppression can be restored by treatment with decorin antisense oligodeoxynucleotides. These effects are independent of growth factors and are not due to either clonal selection or integration site of the decorin gene. These findings correlate well with the observation that decorin gene expression is markedly up-regulated during quiescence. Decorin thus appears to be one component of a negative loop that controls cell growth.

Induction of TH1- and TH2-associated cytokine mRNA in mouse bladder following intravesical growth of the murine bladder tumor MB49 and BCG immunotherapy

Productive immunity to murine and human parasites is associated with the development of a type I T cell response (interferon-gamma-producing) while type II responses (interleukin-4-producing) suppress the development of delayed-type hypersensitivity (DTH) and the elimination of the parasite. To determine if a similar regulatory pathway might exist in tumor systems and may be effected by immunotherapeutic manipulation, we have studied the localized cytokine response to the murine bladder tumor MB49 growing intravesically in syngeneic mice. Intravesical growth of MB49 results in the host-derived expression of mRNA for both interleukin-4 (IL-4) (TH2) and interferon gamma (IFN gamma) (TH1), as well as tumor necrosis factor alpha (TNF alpha) expression of indeterminate origin. Intravesical instillation of bacillus Calmette-Guérin (BCG), highly effective in eliminating bladder tumors clinically and in experimental systems, results in IFN gamma and TNF alpha mRNa production in the bladder wall, but no IL-4. Following BCG treatment of intravesical MB49, the number bladders expressing IL-4 mRNA decreases, while IFN gamma and TNF alpha expression remains constant. These results are consistent with the mechanism of action of BCG involving the generation of an enhanced TH1 immune milieu in the bladder wall, which may contribute to the generation of productive tumor-specific immunity.

Intravesical gene therapy: in vivo gene transfer using recombinant vaccinia virus vectors

Intratumoral gene transfer may be a significant tool in active immunotherapy. The ability to insert functional genes into a tumor in vitro and in vivo using recombinant vaccinia vectors was examined in the murine bladder tumor model. Vaccinia recombinants expressing the influenza hemagglutinin or nucleoprotein antigens infected/transfected murine (MB-49 and MBT-2) and human (T24) bladder tumor cell lines in vitro. Systemic vaccinia immunity was induced with as few as 10 plaque-forming units of recombinant vaccinia instilled intravesically, and the encoded protein was expressed in vivo in tumor and urothelium. However, preimmunity to vaccinia did not inhibit intravesical tumor transfection. Thus, recombinant vaccinia virus is effective in introducing foreign antigens locally into tumor in vivo, supporting its use in clinical immunotherapy.

Intravesical growth of murine bladder tumors assessed by transrectal ultrasound

Experimental studies in the therapy of intravesically growing bladder tumors in mice have been hampered by an inability to monitor tumor growth before and during treatment. To establish a repeatable, noninvasive method to monitor the intravesical growth of bladder tumors, MB49 murine bladder tumor cells were instilled into the bladders of syngeneic C57BL/6 mice. Following 3 weeks of growth, the bladders of tumor-bearing and control mice were imaged using a 20 mHz, 6.2 F catheter-based ultrasound transducer inserted rectally. Bladders of tumor implanted and control mice were identified by high resolution endoluminal ultrasound after distension with 0.15 ml. of normal saline. When compared with the results of histologic analysis, transrectal ultrasound (TRUS) accurately identified tumor presence, size, and location.

Soluble Fc gamma RIII (CD16) and immunoglobulin G levels in seminal plasma of men with immunological infertility

Receptors for the Fc region of the immunoglobulin G (IgG) (Fc gamma R) have been recognized as a link between humoral and cellular immune responses. A soluble form of Fc gamma RIII (CD16) has been found in seminal plasma (SP), which may modulate immunosuppression of antisperm immune responses in the male and female reproductive tracts. SP from some individuals apparently have lower levels of Fc gamma RIII, but it is not known whether the diminished activities are due to low receptor concentration or steric interference from IgG. To test the hypothesis that different levels are due to steric interference, relative levels of Fc gamma RIII were measured in SP using monoclonal antibody 3G8 in an amplified enzyme-linked immunosorbent assay (ELISA) system. Men who were positive for antisperm antibodies (ASA) by Sperm Mar and direct immunobead assay (N = 26) and negative for ASA (N = 26) were tested. Individuals who were ASA positive had lower detectable levels than those who were ASA negative (t = 1.99, P = 0.05). Therefore, variation in Fc gamma RIII levels may be due to steric interference from IgG. IgG subclass concentrations in SP of both groups were determined using an ELISA method and compared to Fc gamma RIII levels. Slight correlations were seen for IgG1 (r2 = 0.237, P < 0.001), IgG2 (r2 = 0.204, P < 0.001), and total IgG (r2 = 0.299, P < 0.001) in relation to Fc gamma RIII levels in ASA-negative SP specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of transitional cell carcinoma of the bladder with intravesical interleukin-2: a pilot study

Human recombinant interleukin-2 (rIL-2) administered systemically can mediate the regression of solid tumors in some patients. IL-2 has been detected in the bladder effluent from patients treated with intravesical BCG for transitional cell carcinoma of the bladder (TCC), suggesting that IL-2 may be an effector molecule in the mechanism of action of BCG. The purpose of the pilot study was to determine the response rate, duration of response and toxicity of rIL-2 (Cetus) administered intravesically to previously untreated patients and patients who had failed prior intravesical therapy with other agents. Fourteen patients with biopsy proven transitional cell carcinoma (13 Stage TIS/Ta/T1, 1 Stage T2) were treated with 8 weekly instillations of 12 x 10(6) IU of rIL-2. An index lesion was followed with cystoscopy, biopsy and cytology at three months, with identical follow up every three months thereafter if a response was noted in the index lesion at the first evaluation. There were 3 complete responses (duration of response measured from start of treatment to date of progression) of 9+, 3, 9 months; one patient with TIS, and 2 patients with Ta disease. There were 11 non-responders for an overall response rate of 21%. One patient with extensive CIS had a dramatic partial response and was converted to a complete response with a second 8-week course of rIL-2. All of the complete responders had failed prior intravesical therapy with standard agents. Toxicity from rIL-2 given intravesically was minimal. One patient reported malaise for 24 hours after each treatment and two patients developed asymptomatic lower UTIs.(ABSTRACT TRUNCATED AT 250 WORDS)