Clinical phase I intratumoral administration of two recombinant ALVAC canarypox viruses expressing human granulocyte-macrophage colony-stimulating factor or interleukin-2: the transgene determines the composition of the inflammatory infiltrate

Oncolytic myxoma virus is effective in murine models of triple negative breast cancer despite poor rates of infection

Oncolytic viruses are being heavily investigated as novel methods to treat cancers; however, predicting their therapeutic efficacy remains challenging. The most commonly used predictive tests involve determining the in vitro susceptibility of a tumor's malignant cells to infection with an oncolytic agent. Whether these tests are truly predictive of in vivo efficacy, however, remains unclear. Here we demonstrate that a recombinant, oncolytic myxoma virus shows efficacy in two murine models of triple negative breast cancer despite extremely low permissivity of these models to viral infection. These data demonstrate that in vitro infectivity studies are not an accurate surrogate for therapeutic efficacy and suggest that other tests need to be developed.

Intratumoral therapies and in-situ vaccination for melanoma

Skin cancers are among the most physically accessible malignancies, so local delivery of a medication into the tumor, so-called intratumoral therapy, is an appealing route of drug administration. Intratumoral therapies have the potential to increase local drug concentration and/or attract immune cells to the local tumor microenvironment, possibly with fewer systemic side effects. A wide array of intratumoral agents have been studied to date in patients with advanced melanoma, including chemotherapeutic drugs, immune modulating agents, and cancer-directed vaccines. In this review, we will summarize the key pre-clinical and clinical data supporting the use of intratumoral therapy for advanced unresectable and metastatic melanoma. First, we will discuss the history of intratumoral immunotherapy for the treatment of melanoma and the various agents studied to date. Second, we will explore how intratumoral therapies can constitute an in situ vaccine, potentially leading to disease control both locally and systemically. Finally, we will highlight opportunities in the field and key future directions.

Intratumoral and Combination Therapy in Melanoma and Other Skin Cancers

Skin cancer, as the most physically accessible malignancy, allows for the greatest variety in treatment innovation. The last 2 decades have seen striking increases in the life expectancies of those diagnosed with malignant melanoma. However, many cases remain in which disease prevails against standard treatment, and those patients rely on continuing ingenuity. Drugs that can be injected directly into patients' tumors have become increasingly promising, not least for the reduction in side effects observed. Intratumoral therapy encompasses a wide array of agents, from chemotherapeutic drugs to cancer vaccines. While each show some efficacy, those agents which regulate the immune system likely have the greatest potential for preventing disease progression or recurrence. Recent research has highlighted the importance of the presence of cytotoxic T cells and of keeping regulatory T cells in check. Thus, manipulating the tumor microenvironment is a need in skin cancer therapy, which intratumoral delivery can potentially address. In order to find the best approach to each person's disease, more studies are needed to test intralesional agents in combination with currently approved therapies and with each other.

Combining talimogene laherparepvec with immunotherapies in melanoma and other solid tumors

Talimogene laherparepvec is a first-in-class intralesional oncolytic immunotherapy. In a recent Phase III trial (OPTiM), talimogene laherparepvec significantly improved durable response rate compared with subcutaneous granulocyte–macrophage colony-stimulating factor (GM-CSF). Overall response rate was also higher in the talimogene laherparepvec arm, and the greatest efficacy was demonstrated in patients with earlier-stage (IIIB, IIIC, or IVM1a) melanoma. Talimogene laherparepvec was well tolerated, with the majority (89%) of adverse events being grade 1 or 2. Preclinical studies have shown that talimogene laherparepvec exerts antitumor activity by selectively replicating within and destroying cancer cells, and through the release of tumor-associated antigens and expression of GM-CSF, which facilitates a wider antitumor immune response. It is hypothesized that combining talimogene laherparepvec with a systemic immunotherapy may, by bringing together complementary mechanisms of action, further enhance the efficacy of both agents. Indeed, talimogene laherparepvec is currently being assessed in combination with immune checkpoint inhibitors, including ipilimumab and pembrolizumab, in trials for melanoma and other solid tumors. Early results in melanoma indicate that the combination of talimogene laherparepvec with ipilimumab or pembrolizumab has greater efficacy than either therapy alone, without additional safety concerns above those expected for each monotherapy. In this review, we discuss the latest results from trials assessing talimogene laherparepvec in combination with other immunotherapies, provide an overview of ongoing and upcoming combination trials, and suggest future directions for talimogene laherparepvec in combination therapy for solid tumors.

Surgical immune interventions for solid malignancies

BACKGROUND

The purpose of this study was to systematically review clinically translatable immunotherapeutic agents that are delivered regionally for solid malignancies.

DATA SOURCES

PubMed and ClinicalTrials.gov were searched for published and registered clinical trials, respectively. The search yielded 334 relevant publications, of which 116 articles were included for review after exclusion criteria were applied.

CONCLUSIONS

There has been an increase in the regional administration of cell-based and viral vector-based clinical trials over the last 5 years. Surgical interventions have been developed for intrapleural, intracranial, intraperitoneal, and intratumoral routes of access to enhance the local delivery of these therapies. Multimodality therapies that combine regional immunotherapy with other local and systemic therapies are demonstrating continued growth as the field of immunotherapy continues to expand.

Intratumoral immunotherapy for melanoma

Selection of suitable tumor-associated antigens is a major challenge in the development of effective cancer vaccines. Intratumoral (i.t.) immunotherapy empowers the immune system to mount T cell responses against tumor-associated antigens which are most immunogenic. To mediate systemic tumor regression, i.t. immunotherapy must generate systemic T cell responses that can target distant metastases beyond the initially treated tumor mass. Now that promising preclinical results and some initial success in clinical trials have been obtained, we here review i.t. immunotherapy-related preclinical and clinical studies, their mechanisms of action and future prospects.

Synergetic Protein Factors That Improve rhGM-CSF Absorption via an Oral Route Exist in Silkworm Pupae

Recent studies have demonstrated that recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) produced by the silkworm pupae bioreactor is absorbed into blood through oral administration and functions as an active cytokine. The aim of this study was to further examine and identify synergetic protein factors in silkworm pupae that improve rhGM-CSF absorption via an oral route. The concentrations of rhGM-CSF in serum were evaluated in mice after oral administration of rhGM-CSF using different chemical compositions of silkworm pupae as pharmaceutical excipients. The experimental data revealed that the supernatant lyophilized powder (SLP) of a homogenized slurry of silkworm pupae caused a significant increase in the rhGM-CSF level in blood when rhGM-CSF was orally administered with SLP, suggesting that synergetic protein factors that improve the oral absorption of rhGM-CSF primarily exist in SLP. As shown by scanning electron microscopy, microspheres were formed when rhGM-CSF was coated with SLP. Animal experimental data showed that the absorption of orally administered rhGM-CSF through the gastrointestinal (GI) tract primarily resulted from protein factors present in the SLP retentate obtained after 10 kDa ultrafiltration. Surface plasmon resonance spectroscopy analysis demonstrated that several protein factors present in the SLP retentate obtained after 10 kDa ultrafiltration were bound to rhGM-CSF. Proteins bound to rhGM-CSF by liquid chromatography-mass spectrometry were identified as chymotrypsin inhibitor SCI-II precursor, cationic peptide CP8 precursor, Kazal-type proteinase inhibitor, and chymotrypsin inhibitor SCI-I. These findings indicate that these proteinase inhibitors play an important role in improving rhGM-CSF absorption in the GI tract.

Immunotherapeutic approaches to hepatocellular carcinoma treatment

Liver cancer, the most common form of which is hepatocellular carcinoma (HCC), is one of the most deadly cancers worldwide. As of 2008, in men, HCC was the fifth most common cancer (approximately 450,000 new cases per year) and the second most frequent cause of death from cancer (around 416,000 deaths per year), whereas in women, it was the seventh most frequently diagnosed cancer (150,000 new cases per year) and the sixth most frequent cause of cancer deaths (140,000 deaths per year) [1]. Overall, HCC is the third leading cause of death from cancer globally [2, 3]. Worldwide, the incidence of HCC in males is more than twice that in females. The etiology of HCC is diverse; however, approximately 80% of HCCs occur secondary to chronic infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) [4]. The geographic distribution of HCC is such that the high-incidence regions of Eastern Asia and sub-Saharan Africa bear a disproportionate HCC burden, amounting to more than 80% of the global burden [4]. However, even in areas considered low-incidence regions-North America and Europe-the incidence of HCC is on the rise [4]. In the US, HCC incidence has risen more than threefold in the past 30 years, and it is now the ninth most frequent cause of death from cancer. The major reasons for the increased incidence of HCC in the US are the increasing prevalence of chronic HCV infection, increased immigration from high-incidence countries in Asia and Africa, and the increase in the number of individuals with cirrhosis due to obesity-related fatty liver disease. Most HCCs are diagnosed at an advanced stage for which there is no curative option. Sorafenib, the only agent specifically approved for HCC treatment, is of limited efficacy in this setting. Therefore, an urgent need for improved HCC therapy exists. In this review, we discuss the available data on the development and use of immunotherapy for HCC, with a particular focus on recent results and novel approaches.

Cancer therapy and vaccination

Cancer remains one of the leading causes of death worldwide, both in developed and in developing nations. It may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Current therapeutic approaches which include surgery, chemotherapy and radiotherapy are associated with adverse side effects arising from lack of specificity for tumors. The goal of any therapeutic strategy is to impact on the target tumor cells with limited detrimental effect to normal cell function. Immunotherapy is cancer specific and can target the disease with minimal impact on normal tissues. Cancer vaccines are capable of generating an active tumor-specific immune response and serve as an ideal treatment due to their specificity for tumor cells and long lasting immunological memory that may safeguard against recurrences. Cancer vaccines are designed to either prevent (prophylactic) or treat established cancer (therapeutic). Identification of tumor-associated antigens (TAAs) and tumor-specific antigens (TSAs) has led to increased efforts to develop vaccination strategies. Vaccines may be composed of whole cells or cell extracts, genetically modified tumor cells to express costimulatory molecules, dendritic cells (DCs) loaded with TAAs, immunization with soluble proteins or synthetic peptides, recombinant viruses or bacteria encoding tumor-associated antigens, and plasmid DNA encoding TSAs or TAAs in conjunction with appropriate immunomodulators. All of these antitumor vaccination approaches aim to induce specific immunological responses and localized to TAAs, destroying tumor cells alone and leaving the vast majority of other healthy cells of the body untouched.

Antigen-specific versus antigen-nonspecific immunotherapeutic approaches for human melanoma: the need for integration for optimal efficacy?

Due to its immunogenecity and evidence of immune responses resulting in tumor regression, metastatic melanoma has been the target for numerous immunotherapeutic approaches. Unfortunately, based on the clinical outcomes, even the successful induction of tumor-specific responses does not correlate with efficacy. Immunotherapies can be divided into antigen-specific approaches, which seek to induce T cells specific to one or several known tumor associated antigens (TAA), or with antigen-nonspecific approaches, which generally activate T cells to become nonspecifically lytic effectors. Here the authors critically review the different immunotherapeutic approaches in melanoma.

Innate immune recognition of poxviral vaccine vectors

The study of poxviruses pioneered the field of vaccinology after Jenner's remarkable discovery that 'vaccination' with the phylogenetically related cowpox virus conferred immunity to the devastating disease of smallpox. The study of poxviruses continues to enrich the field of virology because the global eradication of smallpox provides a unique example of the potency of effective immunization. Other poxviruses have since been developed as vaccine vectors for clinical and veterinary applications and include modified vaccinia virus strains such as modified vaccinia Ankara and NYVAC as well as the avipox viruses, fowlpox virus and canarypox virus. Despite the empirical development of poxvirus-based vectored vaccines, it is only now becoming apparent that we need to better understand how the innate arm of the immune system drives adaptive immunity to poxviruses, and how this information is relevant to vaccine design strategies, which are the topics addressed in this article.

Enhancing the potency of a whole-cell breast cancer vaccine in mice with an antibody-IL-2 immunocytokine that targets exposed phosphatidylserine

Phosphatidylserine (PS), an anionic phospholipid normally restricted to the inner leaflet of the plasma membrane, is immunosuppressive when externalized on the outside of cell membranes. Exposed PS inhibits the maturation and function of dendritic cells (DCs), and induces the production of multiple immunosuppressive mediators. In the present study, we determined whether blocking these effects of PS while simultaneously introducing interleukin-2 (IL-2) could improve the immunogenicity of a whole-cell cancer vaccine. An immunocytokine (2aG4-IL2) was made by genetically linking IL-2 with a PS targeting antibody, 2aG4, that can block the immunosuppressive effects of PS. The 2aG4-IL2/4T1 vaccine was generated by coating the PS exposed on irradiated 4T1 cells with 2aG4-IL2. Tumor growth, spontaneous metastasis, and survival of vaccinated mice challenged with live 4T1 tumor cells were assessed. Eighty percent of mice inoculated with 2aG4-IL2/4T1 vaccine survived free of tumor, as compared with 20% in the 2aG4/4T1 group, 20% in the C44-IL2/4T1 group, and none in the C44/4T1 control group (P=0.001 for 2aG4-IL2/4T1 versus all others groups). The incidence, number of spontaneous lung metastases was significantly lower in the 2aG4-IL2/4T1 vaccinated group than in the other groups. Splenocytes from 2aG4-IL2/4T1 vaccinated mice had significantly higher 4T1 specific cytotoxicity and ability to secrete interferon-gamma (IFNγ) than did splenocytes from mice in the other groups. These results demonstrate that a potent whole-cell vaccine can be created by coating irradiated tumor cells with 2aG4-IL2. Such vaccine could potentially be an effective treatment modality for patients with residual disease or at "high-risk" for recurrence.

Re-inventing intratumoral immunotherapy for melanoma

Immunotherapeutics have been applied intratumorally to manage accessible lesions and to induce systemic immunity in malignant melanoma. Intratumoral bacillus Calmette-Guérin (BCG) has been used for 40 years, and intratumoral BCG, IL-2, IFN-α and imiquimod are recommended as treatment options for patients with in-transit melanoma metastases. Regression of cutaneous metastases can be achieved. Subcutaneous metastases are more refractory, and regression of uninjected, visceral metastases is infrequent. Other microbial products, cytokines, chemicals, immune cells, antibody and viral and plasmid vectors expressing immunologically active molecules have been tested. Antitumor activity has not been demonstrated to be superior to that of intratumoral BCG. There are few controlled trials, and whether survival is impacted with any approach has not yet been established. The immunotherapeutics applied and the intratumoral administration procedure itself can activate responses that are immune inhibitory. More rigorous clinical testing and improved understanding and modulation of regulatory immune responses are necessary.

Intranodal immunization with a vaccinia virus encoding multiple antigenic epitopes and costimulatory molecules in metastatic melanoma

Recombinant vaccinia virus (rVV) encoding tumor-associated antigens (TAAs) and adhesion or costimulatory molecules may represent important immunogenic reagents for cancer immunotherapy. Recently, intranodal (IN) antigen administration was suggested to be more immunogenic than intradermal (ID) vaccination. However, IN rVV administration has not been attempted so far. We used a rVV encoding gp100(280-288), Melan-A/MART-1(27-35) and tyrosinase(1-9) HLA-A0201 restricted epitopes and CD80 and CD86 costimulatory molecules in stage III and IV melanoma patients in a phase 1/2 trial. Of 15 patients initiating treatment, including two cycles of IN immunization, each comprising one rVV administration and three recall injections of the corresponding peptides, accompanied by subcutaneous granulocyte macrophage-colony stimulating factor supplementation, five withdrew due to progressing disease. Of 10 remaining patients seven showed evidence of induction of cytotoxic T lymphocytes (CTLs) directed against at least one epitope under investigation, as detectable by limiting dilution analysis (LDA) of specific precursors and multimer staining. Adverse reactions were mild (National Cancer Institute (NCI) grade 1-2) and mainly represented by fever, skin rashes, and pruritus. These data indicate that IN administration of rVV encoding melanoma-associated epitopes and costimulatory molecules is safe and immunogenic.

Cytokine gene-mediated immunotherapy: current status and future perspectives

Recent understanding of the molecular events crucial in overcoming immunosuppressive tumor microenvironments and generating effective antitumor immunity provides us with the wreath opportunity to manipulate genes that have a key role in antitumor immune responses. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-12 (IL-12) are two indispensable cytokines for activating dendritic cells and boosting the strong immune responses against cancer. In this review, we describe the antitumor mechanisms and clinical application of gene-modified tumor cells and dendritic cells to secrete GM-CSF or IL-12, respectively, in various preclinical and clinical settings. The principles operative in these vaccination strategies may prove applicable to other immunotherapy strategies, especially in combination with other therapeutic modalities, such as chemotherapy and targeted therapy.

Phase I/II open-label study of the biologic effects of the interleukin-2 immunocytokine EMD 273063 (hu14.18-IL2) in patients with metastatic malignant melanoma

Background

To explore the biological activity of EMD 273063 (hu14.18-IL2), a humanized anti-GD2 monoclonal antibody fused to interleukin-2 (IL2), in patients with unresectable, stage IV cutaneous melanoma as measured by induction of immune activation at the tumor site and in peripheral blood.

Methods

Nine patients were treated with 4 mg/m² per day of EMD 273063 given as a 4-h intravenous infusion on days 1, 2, and 3 every four weeks (one cycle). Peripheral blood was analyzed for T cell and natural killer cell phenotype and frequency, as well as levels of soluble IL2 receptor (sIL2R), IL10, IL6, tumor necrosis factor alpha and neopterin. Biopsies of tumor metastasis were performed prior to therapy and at day 10 of the first 2 cycles to study lymphocyte accumulation by immunohistochemistry.

Results

Treatment was generally well tolerated and there were no study drug-related grade 4 adverse events. Grade 3 events were mainly those associated with IL2, most commonly rigors (3 patients) and pyrexia (2 patients). Best response on therapy was stable disease in 2 patients. There were no objective tumor regressions by standard response criteria. Systemic immune activation was demonstrated by increases in serum levels of sIL2R, IL10, and neopterin. There was evidence of increased tumor infiltration by T cells, but not NK cells, in most post-dosing biopsies, suggesting recruitment of immune cells to the tumor site.

Conclusion

EMD 273063 demonstrated biologic activity with increased immune-related cytokines and intratumoral changes in some patients consistent with the suspected mechanism of action of this immunocytokine.

ProtEx technology for the generation of novel therapeutic cancer vaccines

Therapeutic vaccines present an attractive alternative to conventional treatments for cancer. However, tumors have evolved various immune evasion mechanisms to modulate innate, adaptive, and regulatory immunity for survival. Therefore, successful vaccine formulations may require a non-toxic immunomodulator or adjuvant that not only induces/stimulates innate and adaptive tumor-specific immune responses, but also overcomes immune evasion mechanisms. Given the paramount role costimulation plays in modulating innate, adaptive, and regulatory immune responses, costimulatory ligands may serve as effective immunomodulating components of therapeutic cancer vaccines. Our laboratory has developed a novel technology designated as ProtEx that allows for the generation of recombinant costimulatory ligands with potent immunomodulatory activities and the display of these molecules on the cell surface in a rapid and efficient manner as a practical and safe alternative to gene therapy for immunomodulation. Importantly, the costimulatory ligands not only function when displayed on tumor cells, but also as soluble proteins that can be used as immunomodulatory components of conventional vaccine formulations containing tumor-associated antigens (TAAs). We herein discuss the application of the ProtEx technology to the development of effective cell-based as well as cell-free conventional therapeutic cancer vaccines.

Intratumoral injection of alpha-gal glycolipids induces a protective anti-tumor T cell response which overcomes Treg activity

alpha-Gal glycolipids capable of converting tumors into endogenous vaccines, have alpha-gal epitopes (Gal alpha 1-3 Gal beta 1-4GlcNAc-R) and are extracted from rabbit RBC membranes. alpha-Gal epitopes bind anti-Gal, the most abundant natural antibody in humans constituting 1% of immunoglobulins. alpha-Gal glycolipids insert into tumor cell membranes, bind anti-Gal and activate complement. The complement cleavage peptides C5a and C3a recruit inflammatory cells and APC into the treated lesion. Anti-Gal further opsonizes the tumor cells and targets them for effective uptake by recruited APC, via Fc gamma receptors. These APC transport internalized tumor cells to draining lymph nodes, and present immunogenic tumor antigen peptides for activation of tumor specific T cells. The present study demonstrates the ability of alpha-gal glycolipids treatment to prevent development of metastases at distant sites and to protect against tumor challenge in the treated mice. Adoptive transfer studies indicate that this protective immune response is mediated by CD8+ T cells, activated by tumor lesions turned vaccine. This T cell activation is potent enough to overcome the suppressive activity of Treg cells present in tumor bearing mice, however it does not elicit an autoimmune response against antigens on normal cells. Insertion of alpha-gal glycolipids and subsequent binding of anti-Gal are further demonstrated with human melanoma cells, suggesting that intratumoral injection of alpha-gal glycolipids is likely to elicit a protective immune response against micrometastases also in cancer patients.