Paclitaxel Enhances Therapeutic Efficacy of the F8-IL2 Immunocytokine to EDA-Fibronectin–Positive Metastatic Human Melanoma Xenografts

Paclitaxel mediates the PI3K/AKT/mTOR pathway to reduce proliferation of FLT3‑ITD+ AML cells and promote apoptosis

Acute myeloid leukemia (AML) with internal tandem duplication (ITD) mutations in the FLT3 tyrosine kinase tend to have a poor prognosis. FLT3-ITD can promote the progress of AML by activating the PI3K/AKT/mTOR pathway. Paclitaxel (PTX) is a natural anticancer drug that has been widely used in chemotherapy for multiple malignancies. The present study used the CCK-8 assay, flow cytometry, PCR and western blotting to explore the anti-leukemia effect and possible mechanisms of PTX on MV4-11 cells with the FLT3-ITD mutation and the underlying mechanism. As a result, it was found that PTX could inhibit proliferation of MV4-11 cells and promoted apoptosis by inhibiting the PI3K/AKT/mTOR pathway.

Intratumoral Treatment of Melanoma Tumors with Large Surface Area Microparticle Paclitaxel and Synergy with Immune Checkpoint Inhibition

The effects of intratumoral (IT) large surface area microparticle paclitaxel (LSAM-PTX) alone and in combination with systemic administration of the programmed cell death protein antibody (anti-mPD-1) were evaluated in a syngeneic murine model of melanoma. Groups of mice with subcutaneously implanted Clone M3 (Cloudman S91) tumors were treated with single and combination therapies. Tumor volume (TV) measurements, body weights, and clinical observations were followed in-life. At end of study, tumor-site tissues were collected, measured, and processed for flow cytometry along with blood and lymph nodes. The combination of LSAM-PTX + anti-mPD-1 resulted in an antitumoral response, which produced a significant decrease in TV compared to control animals. TV decreases also occurred in the LSAM-PTX and anti-mPD-1 groups. Flow cytometry analysis found increases in granulocytes and M2 macrophages and decreases in dendritic cells (DC) and monocytic myeloid-derived suppressor cells (M-MDSC) in tumor-site tissues. Increases in granulocytes and decreases in CD4+ T cells, macrophages, and M1 macrophages were found in the blood of animals administered the combination treatment. Increases in natural killer (NK) cells were found in lymph node tissue in the combination treatment group. These findings suggest that IT LSAM-PTX may provide benefit in the local treatment of melanomas and may synergize with systemic anti-PD-1 therapy, leading to additional tumoricidal outcomes without added systemic toxicity.

The nexus of natural killer cells and melanoma tumor microenvironment: crosstalk, chemotherapeutic potential, and innovative NK cell-based therapeutic strategies

The metastasis of melanoma cells to regional lymph nodes and distant sites is an important contributor to cancer-related morbidity and mortality among patients with melanoma. This intricate process entails dynamic interactions involving tumor cells, cellular constituents, and non-cellular elements within the microenvironment. Moreover, both microenvironmental and systemic factors regulate the metastatic progression. Central to immunosurveillance for tumor cells are natural killer (NK) cells, prominent effectors of the innate immune system with potent antitumor and antimetastatic capabilities. Recognizing their pivotal role, contemporary immunotherapeutic strategies are actively integrating NK cells to combat metastatic tumors. Thus, a meticulous exploration of the interplay between metastatic melanoma and NK cells along the metastatic cascade is important. Given the critical involvement of NK cells within the melanoma tumor microenvironment, this comprehensive review illuminates the intricate relationship between components of the melanoma tumor microenvironment and NK cells, delineating their multifaceted roles. By shedding light on these critical aspects, this review advocates for a deeper understanding of NK cell dynamics within the melanoma context, driving forward transformative strategies to combat this cancer.

Tumor-Targeted Interleukin 2 Boosts the Anticancer Activity of FAP-Directed Radioligand Therapeutics

We studied the antitumor efficacy of a combination of 177Lu-labeled radioligand therapeutics targeting the fibroblast activation protein (FAP) (OncoFAP and BiOncoFAP) with the antibody-cytokine fusion protein L19-interleukin 2 (L19-IL2) providing targeted delivery of interleukin 2 to tumors. Methods: The biodistribution of 177Lu-OncoFAP and 177Lu-BiOncoFAP at different molar amounts (3 vs. 250 nmol/kg) of injected ligand was studied via SPECT/CT in mice bearing subcutaneous HT-1080.hFAP tumors, and self-absorbed tumor and organ doses were calculated. The in vivo anticancer effect of 5 MBq of the radiolabeled preparations was evaluated as monotherapy or in combination with L19-IL2 in subcutaneously implanted HT-1080.hFAP and SK-RC-52.hFAP tumors. Tumor samples from animals treated with 177Lu-BiOncoFAP, L19-IL2, or both were analyzed by mass spectrometry-based proteomics to identify therapeutic signatures on cellular and stromal markers of cancer and on immunomodulatory targets. Results: 177Lu-BiOncoFAP led to a significantly higher self-absorbed dose in FAP-positive tumors (0.293 ± 0.123 Gy/MBq) than did 177Lu-OncoFAP (0.157 ± 0.047 Gy/MBq, P = 0.01) and demonstrated favorable tumor-to-organ ratios at high molar amounts of injected ligand. Administration of L19-IL2 or 177Lu-BiOncoFAP as single agents led to cancer cures in only a limited number of treated animals. In 177Lu-BiOncoFAP-plus-L19-IL2 combination therapy, complete remissions were observed in all injected mice (7/7 complete remissions for the HT-1080.hFAP model, and 4/4 complete remissions for the SK-RC-52.hFAP model), suggesting therapeutic synergy. Proteomic studies revealed a mechanism of action based on the activation of natural killer cells, with a significant enhancement of the expression of granzymes and perforin 1 in the tumor microenvironment after combination treatment. Conclusion: The combination of OncoFAP-based radioligand therapeutics with concurrent targeting of interleukin 2 shows synergistic anticancer effects in the treatment of FAP-positive tumors. This experimental finding should be corroborated by future clinical studies.

Multivalent dipeptidyl peptidase IV fragment-nanogold complex inhibits cancer metastasis by blocking pericellular fibronectin

Inhibition of cancer metastasis is a fundamental challenge in cancer treatment. We have previously shown that metastasis of cancer cells in the lung is critically promoted by the interaction between the superficial dipeptidyl peptidase IV (DPP IV) expressed on lung endothelial cells and the pericellular polymeric fibronectin (polyFN) of circulating cancer cells. In the present study, we aimed to search for DPP IV fragments with high avidity to polyFN and develop FN-targeted gold nanoparticles (AuNPs) conjugated with DPP IV fragments for treating cancer metastasis. We first identified a DPP IV fragment encompassing amino acids 29-130 of DPP IV, designated DP4A, which contained FN-binding sites and could specifically bind to FN immobilized on gelatin agarose beads. Furthermore, we conjugated maltose binding protein (MBP)-fused DP4A proteins to AuNPs for fabricating a DP4A-AuNP complex and evaluated its FN-targeted activity in vitro and anti-metastatic efficacy in vivo. Our results show that DP4A-AuNP exhibited higher binding avidity to polyFN than DP4A by 9 folds. Furthermore, DP4A-AuNP was more potent than DP4A in inhibiting DPP IV binding to polyFN. In terms of polyFN-targeted effect, DP4A-AuNP interacted with FN-overexpressing cancer cells and was endocytosed into cells 10 to 100 times more efficiently than untargeted MBP-AuNP or PEG-AuNP with no noticeable cytotoxicity. Furthermore, DP4A-AuNP was superior to DP4A in competitive inhibition of cancer cell adhesion to DPP IV. Confocal microscopy analysis revealed that binding of DP4A-AuNP to pericellular FN induced FN clustering without altering its surface expression on cancer cells. Notably, intravenous treatment with DP4A-AuNP significantly reduced metastatic lung tumor nodules and prolonged the survival in the experimental metastatic 4T1 tumor model. Collectively, our findings suggest that the DP4A-AuNP complex with potent FN-targeted effects may have therapeutic potential for prevention and treatment of tumor metastasis to the lung.

Synergetic effect of high dose rate radiations (10× FFF/2400 MU/min/10 MV x-rays) and paclitaxel selectively eliminates melanoma cells

BACKGROUND

Melanoma is one of the most aggressive cancers, with 1.6% of total cancer deaths in the United States. In recent years treatment options for metastatic melanoma have been improved by the FDA approval of new therapeutic agents. However, these inhibitors-based therapies are non-specific and have severe toxicities, including hyperkeratosis, photosensitivity, hepatitis, arthralgia, and fatigue.

AIMS

The aim of this study is to determine the synthetic lethal effect (paclitaxel and radiations) on melanoma cells and reduce the total radiation doses by increasing the dose rates up to 2400 MU/min.

METHODS AND RESULTS

We previously reported a radiation treatment (10 MV x-rays, 10X-FFF, dose rate 2400MU/min, low total dose 0.5 Gy) that kills melanoma cells with 80% survival of normal HEM in vitro. In this study, we extended the radiation cycle up to four and included paclitaxel treatment to study the synthetic lethal effect on melanoma and two other normal primary cells, HDF and HEK. Cells were treated with paclitaxel prior to the radiation at a dose rate of 400 and 2400 MU/min with a total radiation dose of only 0.5 Gy. Mitochondrial respiration assay, DNA damage assay, and colony formation assays were performed to study apoptosis and cell death induction. Four days of consequent radiation treatment with paclitaxel significantly reduces the survival of melanoma cells by inducing apoptosis and mitochondrial damage. After treatment, excessive DNA damage in melanoma cells leads to an increase in the expression of pro-apoptotic genes (Caspase-3) and a decrease in the expression of DNA repair gene (PARP1) and anti-apoptotic gene (Bcl-2) to activate the apoptosis pathway. The combination of paclitaxel and radiation reduces the survival of melanoma cells colonies compared to radiation alone.

CONCLUSION

Our study indicates that radiations with paclitaxel have a potential synthetic lethal effect on melanoma cells and can be developed as a melanoma therapy without toxicities or harmful effects on normal primary skin cells.

HSPB8 counteracts tumor activity of BRAF- and NRAS-mutant melanoma cells by modulation of RAS-prenylation and autophagy

Cutaneous melanoma is one of the most aggressive and lethal forms of skin cancer. Some specific driver mutations have been described in multiple oncogenes including BRAF and NRAS that are mutated in 60-70% and 15-20% of melanoma, respectively. The aim of this study was to evaluate the role of Small Heat Shock Protein B8 (HSPB8) on cell growth and migration of both BLM (BRAF^wt/NRAS^Q61R) and A375 (BRAF^V600E/NRAS^wt) human melanoma cell lines. HSPB8 is a member of the HSPB family of chaperones involved in protein quality control (PQC) system and contributes to chaperone assisted selective autophagy (CASA) as well as in the regulation of mitotic spindle. In cancer, HSPB8 has anti- or pro-tumoral action depending on tumor type. In melanoma cell lines characterized by low HSPB8 levels, we demonstrated that the restoration of HSPB8 expression causes cell growth arrest, reversion of EMT (Epithelial-Mesenchymal Transition)-like phenotype switching and antimigratory effect, independently from the cell mutational status. We demonstrated that HSPB8 regulates the levels of the active prenylated form of NRAS in NRAS-mutant and NRAS-wild-type melanoma cell lines. Consequently, the inhibition of NRAS impairs the activation of Akt/mTOR pathway inducing autophagy activation. Autophagy can play a dual role in regulating cell death and survival. We have therefore demonstrated that HSPB8-induced autophagy is a crucial event that counteracts cell growth in melanoma. Collectively, our results suggest that HSPB8 has an antitumoral action in melanoma cells characterized by BRAF and NRAS mutations.

Recent Progress on the Role of Fibronectin in Tumor Stromal Immunity and Immunotherapy

As a major component of the stromal microenvironment of various solid tumors, the extracellular matrix (ECM) has attracted increasing attention in cancer-related studies. ECM in the tumor stroma not only provides an external barrier and framework for tumor cell adhesion and movement, but also acts as an active regulator that modulates the tumor microenvironment, including stromal immunity. Fibronectin (Fn), as a core component of the ECM, plays a key role in the assembly and remodeling of the ECM. Hence, understanding the role of Fn in the modulation of tumor stromal immunity is of great importance for cancer immunotherapy. Hence, in-depth studies on the underlying mechanisms of Fn in tumors are urgently needed to clarify the current understanding and issues and to identify new and specific targets for effective diagnosis and treatment purposes. In this review, we summarize the structure and role of Fn, its potent derivatives in tumor stromal immunity, and their biological effects and mechanisms in tumor development. In addition, we discuss the novel applications of Fn in tumor treatment. Therefore, this review can provide prospective insight into Fn immunotherapeutic applications in tumor treatment.

Targeting the extra domain A of fibronectin for cancer therapy with CAR-T cells

BACKGROUND

One of the main difficulties of adoptive cell therapies with chimeric antigen receptor (CAR)-T cells in solid tumors is the identification of specific target antigens. The tumor microenvironment can present suitable antigens for CAR design, even though they are not expressed by the tumor cells. We have generated a CAR specific for the splice variant extra domain A (EDA) of fibronectin, which is highly expressed in the tumor stroma of many types of tumors but not in healthy tissues.

METHODS

EDA expression was explored in RNA-seq data from different human tumor types and by immunohistochemistry in paraffin-embedded tumor biopsies. Murine and human anti-EDA CAR-T cells were prepared using recombinant retro/lentiviruses, respectively. The functionality of EDA CAR-T cells was measured in vitro in response to antigen stimulation. The antitumor activity of EDA CAR-T cells was measured in vivo in C57BL/6 mice challenged with PM299L-EDA hepatocarcinoma cell line, in 129Sv mice-bearing F9 teratocarcinoma and in NSG mice injected with the human hepatocarcinoma cell line PLC.

RESULTS

EDA CAR-T cells recognized and killed EDA-expressing tumor cell lines in vitro and rejected EDA-expressing tumors in immunocompetent mice. Notably, EDA CAR-T cells showed an antitumor effect in mice injected with EDA-negative tumor cells lines when the tumor stroma or the basement membrane of tumor endothelial cells express EDA. Thus, EDA CAR-T administration delayed tumor growth in immunocompetent 129Sv mice challenged with teratocarcinoma cell line F9. EDA CAR-T treatment exerted an antiangiogenic effect and significantly reduced gene signatures associated with epithelial-mesenchymal transition, collagen synthesis, extracellular matrix organization as well as IL-6-STAT5 and KRAS pathways. Importantly, the human version of EDA CAR, that includes the human 41BB and CD3ζ endodomains, exerted strong antitumor activity in NSG mice challenged with the human hepatocarcinoma cell line PLC, which expresses EDA in the tumor stroma and the endothelial vasculature. EDA CAR-T cells exhibited a tropism for EDA-expressing tumor tissue and no toxicity was observed in tumor bearing or in healthy mice.

CONCLUSIONS

These results suggest that targeting the tumor-specific fibronectin splice variant EDA with CAR-T cells is feasible and offers a therapeutic option that is applicable to different types of cancer.

Synergistic effect of Abraxane that combines human IL15 fused with an albumin-binding domain on murine models of pancreatic ductal adenocarcinoma

Nab‐paclitaxel (Abraxane), which is a nanoparticle form of albumin‐bound paclitaxel, is one of the standard chemotherapies for pancreatic ductal adenocarcinoma (PDAC). This study determined the effect of Abraxane in combination with a fusion protein, hIL15‐ABD, on subcutaneous Panc02 and orthotopic KPC C57BL/6 murine PDAC models. Abraxane combined with hIL15‐ABD best suppressed tumour growth and produced a 40%–60% reduction in the tumour size for Panc02 and KPC, compared to the vehicle group. In the combination group, the active form of interferon‐γ (IFN‐γ)‐secreting CD8⁺ T cells and CD11b⁺CD86⁺ M1 macrophages in tumour infiltrating lymphocytes (TILs) were increased. In the tumour drainage lymph nodes (TDLNs) of the combination group, there was a 18% reduction in CD8⁺IFN‐γ⁺ T cells and a 0.47% reduction in CD4⁺CD25⁺FOXP3⁺ regulatory T cells, as opposed to 5.0% and 5.1% reductions, respectively, for the control group. Superior suppression of CD11b⁺GR‐1⁺ myeloid‐derived suppressor cells (MDSCs) and the induction of M1 macrophages in the spleen and bone marrow of mice were found in the combination group. Abraxane and hIL15‐ABD effectively suppressed NF‐κB‐mediated immune suppressive markers, including indoleamine 2,3‐dioxygenase (IDO), Foxp3 and VEGF. In conclusion, Abraxane combined with hIL15‐ABD stimulates the anticancer activity of effector cells, inhibits immunosuppressive cells within the tumour microenvironment (TME) of PDAC, and produces a greater inhibitory effect than individual monotherapies.

Interleukin 2-Based Fusion Proteins for the Treatment of Cancer

Interleukin 2 (IL-2) plays a fundamental role in both immune activation and tolerance and has revolutionized the field of cancer immunotherapy since its discovery. The ability of IL-2 to mediate tumor regression in preclinical and clinical settings led to FDA approval for its use in the treatment of metastatic renal cell carcinoma and metastatic melanoma in the 1990s. Although modest success is observed in the clinic, cancer patients receiving IL-2 therapy experience a wide array of side effects ranging from flu-like symptoms to life-threatening conditions such as vascular leak syndrome. Over the past three decades, efforts have focused on circumventing IL-2-related toxicities by engineering methods to localize IL-2 to the tumor or secondary lymphoid tissue, preferentially activate CD8⁺ T cells and NK cells, and alter pharmacokinetic properties to increase bioavailability. This review summarizes the various IL-2-based strategies that have emerged, with a focus on chimeric fusion methods.

NK Cells in the Tumor Microenvironment as New Potential Players Mediating Chemotherapy Effects in Metastatic Melanoma

Until the last decade, chemotherapy was the standard treatment for metastatic cutaneous melanoma, even with poor results. The introduction of immune checkpoints inhibitors (ICIs) radically changed the outcome, increasing 5-year survival from 5% to 60%. However, there is still a large portion of unresponsive patients that would need further therapies. NK cells are skin-resident innate cytotoxic lymphocytes that recognize and kill virus-infected as well as cancer cells thanks to a balance between inhibitory and activating signals delivered by surface molecules expressed by the target. Since NK cells are equipped with cytotoxic machinery but lack of antigen restriction and needing to be primed, they are nowadays gaining attention as an alternative to T cells to be exploited in immunotherapy. However, their usage suffers of the same limitations reported for T cells, that is the loss of immunogenicity by target cells and the difficulty to penetrate and be activated in the suppressive tumor microenvironment (TME). Several evidence showed that chemotherapy used in metastatic melanoma therapy possess immunomodulatory properties that may restore NK cells functions within TME. Here, we will discuss the capability of such chemotherapeutics to: i) up-regulate melanoma cells susceptibility to NK cell-mediated killing, ii) promote NK cells infiltration within TME, iii) target other immune cell subsets that affect NK cells activities. Alongside traditional systemic melanoma chemotherapy, a new pharmacological strategy based on nanocarriers loaded with chemotherapeutics is developing. The use of nanotechnologies represents a very promising approach to improve drug tolerability and effectiveness thanks to the targeted delivery of the therapeutic molecules. Here, we will also discuss the recent developments in using nanocarriers to deliver anti-cancer drugs within the melanoma microenvironment in order to improve chemotherapeutics effects. Overall, we highlight the possibility to use standard chemotherapeutics, possibly delivered by nanosystems, to enhance NK cells anti-tumor cytotoxicity. Combined with immunotherapies targeting NK cells, this may represent a valuable alternative approach to treat those patients that do not respond to current ICIs.

Immunoengineering approaches for cytokine therapy

Since the discovery of cytokines, much effort has been put forth to achieve therapeutic translation for treatment of various diseases, including cancer and autoimmune diseases. Despite these efforts, very few cytokines have cleared regulatory approval, and those that were approved are not commonly used due to their challenging toxicity profile and/or limited therapeutic efficacy. The main limitation in translation has been that wild-type cytokines have unfavorable pharmacokinetic and pharmacodynamic profiles, either eliciting unwanted systemic side effects or insufficient residence in secondary lymphoid organs. In this review, we address protein-engineering approaches that have been applied to both proinflammatory and anti-inflammatory cytokines to enhance their therapeutic indices, and we highlight diseases in which administration of engineered cytokines is especially relevant.

An ultra-high-affinity small organic ligand of fibroblast activation protein for tumor-targeting applications

We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP in order to study biodistribution properties and tumor-targeting performance in preclinical models. Fluorescent derivatives selectively localized in FAP-positive tumors implanted in nude mice with a rapid and homogeneous penetration within the neoplastic tissue. Quantitative in vivo biodistribution studies with a lutetium-177-labeled derivative of OncoFAP revealed a preferential localization in tumors at doses of up to 1,000 nmol/kg. More than 30% of the injected dose had already accumulated in 1 g of tumor 10 min after intravenous injection and persisted for at least 3 h with excellent tumor-to-organ ratios. OncoFAP also served as a modular component for the generation of nonradioactive therapeutic products. A fluorescein conjugate mediated a potent and FAP-dependent tumor cell killing activity in combination with chimeric antigen receptor (CAR) T cells specific to fluorescein. Similarly, a conjugate of OncoFAP with the monomethyl auristatin E-based Vedotin payload was well tolerated and cured tumor-bearing mice in combination with a clinical-stage antibody-interleukin-2 fusion. Collectively, these data support the development of OncoFAP-based products for tumor-targeting applications in patients with cancer.

Utilizing Immunocytokines for Cancer Therapy

Cytokine therapy for cancer has indicated efficacy in certain diseases but is generally accompanied by severe toxicity. The field of antibody-cytokine fusion proteins (immunocytokines) arose to target these effector molecules to the tumor environment in order to expand the therapeutic window of cytokine therapy. Pre-clinical evidence has shown the increased efficacy and decreased toxicity of various immunocytokines when compared to their cognate unconjugated cytokine. These anti-tumor properties are markedly enhanced when combined with other treatments such as chemotherapy, radiotherapy, and checkpoint inhibitor antibodies. Clinical trials that have continued to explore the potential of these biologics for cancer therapy have been conducted. This review covers the in vitro, in vivo, and clinical evidence for the application of immunocytokines in immuno-oncology.

Immunotherapy with Immunocytokines and PD-1 Blockade Enhances the Anticancer Activity of Small Molecule-Drug Conjugates Targeting Carbonic Anhydrase IX

Small molecule-drug conjugates (SMDCs) represent an alternative to conventional antitumor chemotherapeutic agents, with the potential to improve the therapeutic window of cytotoxic payloads through active delivery at the site of the disease. In this article, we describe novel combination therapies consisting of anti-carbonic anhydrase IX SMDCs combined with different immunomodulatory products. The therapeutic effect of the SMDCs was potentiated by combination with PD-1 blockade and with tumor-homing antibody-cytokine fusions in mouse models of renal cell carcinoma and colorectal cancer. The combination with L19-IL12, a fusion protein specific to the alternatively spliced EDB domain of fibronectin containing the murine IL12 moiety, was also active against large established tumors. Analysis of the microscopic structures of healthy organs performed 3 months after tumor eradication confirmed absence of pathologic abnormalities in the healthy kidney, liver, lung, stomach, and intestine. Our findings may be of clinical significance as they provide motivation for the development of combinations based on SMDCs and immunotherapy for the treatment of renal cell carcinoma and hypoxic tumors.

Alternative splicing in endothelial cells: novel therapeutic opportunities in cancer angiogenesis

Alternative splicing (AS) is a pervasive molecular process generating multiple protein isoforms, from a single gene. It plays fundamental roles during development, differentiation and maintenance of tissue homeostasis, while aberrant AS is considered a hallmark of multiple diseases, including cancer. Cancer-restricted AS isoforms represent either predictive biomarkers for diagnosis/prognosis or targets for anti-cancer therapies. Here, we discuss the contribution of AS regulation in cancer angiogenesis, a complex process supporting disease development and progression. We consider AS programs acting in a specific and non-redundant manner to influence morphological and functional changes involved in cancer angiogenesis. In particular, we describe relevant AS variants or splicing regulators controlling either secreted or membrane-bound angiogenic factors, which may represent attractive targets for therapeutic interventions in human cancer.

Local administration of submicron particle paclitaxel to solid carcinomas induces direct cytotoxicity and immune-mediated tumoricidal effects without local or systemic toxicity: preclinical and clinical studies

This report describes local administration of submicron particle paclitaxel (SPP) (NanoPac®: ~ 800-nm-sized particles with high relative surface area with each particle containing ~ 2 billion molecules of paclitaxel) in preclinical models and clinical trials evaluating treatment of carcinomas. Paclitaxel is active in the treatment of epithelial solid tumors including ovarian, peritoneal, pancreatic, breast, esophageal, prostate, and non-small cell lung cancer. SPP has been delivered directly to solid tumors, where the particles are retained and continuously release the drug, exposing primary tumors to high, therapeutic levels of paclitaxel for several weeks. As a result, tumor cell death shifts from primarily apoptosis to both apoptosis and necroptosis. Direct local tumoricidal effects of paclitaxel, as well as stimulation of innate and adaptive immune responses, contribute to antineoplastic effects. Local administration of SPP may facilitate tumor response to systemically administered chemotherapy, targeted therapy, or immunotherapy without contributing to systemic toxicity. Results of preclinical and clinical investigations described here suggest that local administration of SPP achieves clinical benefit with negligible toxicity and may complement standard treatments for metastatic disease.

Fibronectin and colorectal cancer: signaling pathways and clinical implications

Colorectal cancer (CRC) is the fourth leading cause of cancer deaths worldwide, with poor prognosis mainly related to metastasis. Fibronectin (FN), a vital component of the extracellular matrix (ECM), has been found involved in tumorigenesis and malignant progression in different types of malignancy. Numerous studies have indicated the distinct expression of FN in various cancers and demonstrated the different functions of FN in the proliferation, migration, and invasion of cancers. Meanwhile, FN isoforms have been extensively used for targeted drug delivery and imaging for tumors. Although a growing number of studies on FN in CRC have been reported, integrated reviews on the relationship between FN and CRC are rare. In this review, we will summarize the association between FN and CRC, including the signaling pathways and molecules involved in, as well as potential diagnostic and therapeutic values of FN for patients with CRC.

Trabectedin and Lurbinectedin Extend Survival of Mice Bearing C26 Colon Adenocarcinoma, without Affecting Tumor Growth or Cachexia

Trabectedin (ET743) and lurbinectedin (PM01183) limit the production of inflammatory cytokines that are elevated during cancer cachexia. Mice carrying C26 colon adenocarcinoma display cachexia (i.e., premature death and body wasting with muscle, fat and cardiac tissue depletion), high levels of inflammatory cytokines and subsequent splenomegaly. We tested whether such drugs protected these mice from cachexia. Ten-week-old mice were inoculated with C26 cells and three days later randomized to receive intravenously vehicle or 0.05 mg/kg ET743 or 0.07 mg/kg PM01183, three times a week for three weeks. ET743 or PM01183 extended the lifespan of C26-mice by 30% or 85%, respectively, without affecting tumor growth or food intake. Within 13 days from C26 implant, both drugs did not protect fat, muscle and heart from cachexia. Since PM01183 extended the animal survival more than ET743, we analyzed PM01183 further. In tibialis anterior of C26-mice, but not in atrophying myotubes, PM01183 restrained the NF-κB/PAX7/myogenin axis, possibly reducing the pro-inflammatory milieu, and failed to limit the C/EBPβ/atrogin-1 axis. Inflammation-mediated splenomegaly of C26-mice was inhibited by PM01183 for as long as the treatment lasted, without reducing IL-6, M-CSF or IL-1β in plasma. ET743 and PM01183 extend the survival of C26-bearing mice unchanging tumor growth or cachexia but possibly restrain muscle-related inflammation and C26-induced splenomegaly.

Antibody-Cytokine Fusions: Versatile Products for the Modulation of Anticancer Immunity

The remarkable clinical success of immune-checkpoint inhibitors for the treatment of a growing number of cancer types has sparked interest in the discovery of novel forms of immunotherapy, which may be used alone or in combination. In this context, cytokine-based therapeutics are well poised to play a role in modern cancer therapy. This article focuses on antibody-cytokine fusion proteins (also called "immunocytokines") as one class of biopharmaceuticals that can substantially improve the therapeutic index and, thus, the applicability of cytokine products. In many preclinical settings, antibodies can be used to preferentially deliver many (but not all) types of cytokines to primary and metastatic tumor lesions. The antibody-based delivery of certain proinflammatory payloads (such as IL2, IL12, and TNF) to the tumor microenvironment can lead to a dramatic potentiation of their anticancer activity. However, although some fusion proteins have advanced to late-stage clinical trials, much work remains to be done in order to fully characterize the mechanism of action and the pharmaceutical potential of immunocytokines in the clinical setting. Various factors contribute to in vivo performance, including the target antigen, the antibody properties, the nature of the payload, the format of the fusion protein, the dose, and schedule, as well as their use in combination with other therapeutic modalities. Protein engineering opportunities and insights in cancer immunology are contributing to the development of next-generation immunocytokine products and of novel therapeutic concepts, with the goal to increase antitumor activity and reduce systemic toxicity (a common problem for cytokine-based biopharmaceuticals).

Identification of a natural compound, sesamin, as a novel TRPM8 antagonist with inhibitory effects on prostate adenocarcinoma

Transient receptor potential melastatin 8 (TRPM8) is a calcium ion-permeable cation channel that is used as a prognostic marker and therapeutic target for different tumor types. To identify natural selective TRPM8 antagonists, we tested 158 traditional Chinese medicine (TCM) compounds for the ability to inhibit TRPM8. Calcium mobilization assays were used to evaluate the 158 TCM compound components in HEK293 cells stably expressing TRPM8. An identified putative TRPM8 antagonist, sesamin, was further evaluated. Publicly available cancer OMICS data were used to explore the expression of TRPM8, its gene regulatory network, and the survival of patients with prostate adenocarcinoma (PRAD). The cytotoxicity and specificity of sesamin to TRPM8 were tested in HEK293/TRPM8 cells. The effect of sesamin on cell proliferation in PRAD cell lines was assessed. Sesamin selectively inhibited TRPM8 in HEK293/TRPM8 cells (IC50: 9.78 μM), and a molecular docking study confirmed the binding of sesamin to TRPM8. TRPM8 was highly overexpressed in PRAD, and high TRPM8 expression was associated with poor survival of PRAD patients. Functional network analysis suggested that TRPM8 has key effects on proliferation, survival, and invasion of prostate cancer cells. Cell proliferation assays supported these findings and showed that sesamin inhibited the proliferation of PRAD cell lines DU145 and LNCaP cells. These data revealed that abnormal TRPM8 expression is associated with PRAD and that sesamin is a new anti-PRAD candidate drug, exerting inhibitory effects on TRPM8.

Fibronectin in Cancer: Friend or Foe

The role of fibronectin (FN) in tumorigenesis and malignant progression has been highly controversial. Cancerous FN plays a tumor-suppressive role, whereas it is pro-metastatic and associated with poor prognosis. Interestingly, FN matrix deposited in the tumor microenvironments (TMEs) promotes tumor progression but is paradoxically related to a better prognosis. Here, we justify how FN impacts tumor transformation and subsequently metastatic progression. Next, we try to reconcile and rationalize the seemingly conflicting roles of FN in cancer and TMEs. Finally, we propose future perspectives for potential FN-based therapeutic strategies.

Antibody-cytokine fusion proteins: A novel class of biopharmaceuticals for the therapy of cancer and of chronic inflammation

Antibody-cytokine fusion proteins represent a novel class of biopharmaceuticals, with the potential to increase the therapeutic index of cytokine 'payloads' and to promote leukocyte infiltration at the site of disease. In this review, we present a survey of immunocytokines that have been used in preclinical models of cancer and in clinical trials. In particular, we highlight how antibody format, choice of target antigen and cytokine engineering, as well as combination strategies, may have a profound impact on therapeutic performance. Moreover, by using anti-inflammatory cytokines, antibody fusion strategies can conveniently be employed for the treatment of auto-immune and chronic inflammatory conditions.

Targeted Delivery of IL2 to the Tumor Stroma Potentiates the Action of Immune Checkpoint Inhibitors by Preferential Activation of NK and CD8+ T Cells

Recombinant human IL2 is being considered as a combination partner for immune checkpoint inhibitors in cancer therapy, but the product only has a narrow therapeutic window. Therefore, we used F8-IL2, an antibody-IL2 fusion protein capable of selective localization to the tumor site, in combination with antibodies against murine CTLA-4, PD-1, and PD-L1. In immunocompetent mice bearing CT26 tumors, the combination of F8-IL2 with CTLA-4 blockade was efficacious, leading to increased progression-free survival and protective immunity against subsequent tumor rechallenges. The combination with anti-PD-1 induced substantial tumor growth retardation, but tumor clearance was rare, whereas the combination with anti-PD-L1 exhibited the lowest activity. A detailed high-parametric single-cell analysis of the tumor leukocyte composition revealed that F8-IL2 had a strong impact on NK-cell activity without collateral immune activation in the systemic immune compartment, whereas CTLA-4 blockade led to significant changes in the T-cell compartment. Leukocyte depletion studies revealed that CD8⁺ T and NK cells were the main drivers of the therapeutic activity. We extended the experimental observations to a second model, treating MC38 tumor-bearing mice with F8-IL2 and/or CTLA-4 blockade. Only the combination treatment displayed potent anticancer activity, characterized by an increase in cytolytic CD8⁺ T and NK cells in tumors and draining lymph nodes. A decrease in the regulatory T cell frequency, within the tumors, was also observed. The results provide a rationale for the combined use of engineered IL2 therapeutics with immune checkpoint inhibitors for cancer therapy.

Antibody-cytokine fusion proteins: Biopharmaceuticals with immunomodulatory properties for cancer therapy

Cytokines have long been used for therapeutic applications in cancer patients. Substantial side effects and unfavorable pharmacokinetics limit their application and may prevent dose escalation to therapeutically active regimens. Antibody-cytokine fusion proteins (often referred to as immunocytokines) may help localize immunomodulatory cytokine payloads to the tumor, thereby activating anticancer immune responses. A variety of formats (e.g., intact IgGs or antibody fragments), molecular targets (e.g., extracellular matrix components and cell membrane antigens) and cytokine payloads have been considered for the development of this novel class of biopharmaceuticals. This review presents the basic concepts on the design and engineering of immunocytokines, reviews their potential limitations, points out emerging opportunities and summarizes key features of preclinical and clinical-stage products.

Anti-cancer Therapies Employing IL-2 Cytokine Tumor Targeting: Contribution of Innate, Adaptive and Immunosuppressive Cells in the Anti-tumor Efficacy

Antibody-cytokine fusion proteins (immunocytokine) exert a potent anti-cancer effect; indeed, they target the immunosuppressive tumor microenvironment (TME) due to a specific anti-tumor antibody linked to immune activating cytokines. Once bound to the target tumor, the interleukin-2 (IL-2) immunocytokines composed of either full antibody or single chain Fv conjugated to IL-2 can promote the in situ recruitment and activation of natural killer (NK) cells and cytotoxic CD8⁺ T lymphocytes (CTL). This recruitment induces a TME switch toward a classical T helper 1 (Th1) anti-tumor immune response, supported by the cross-talk between NK and dendritic cells (DC). Furthermore, some IL-2 immunocytokines have been largely shown to trigger tumor cell killing by antibody dependent cellular cytotoxicity (ADCC), through Fcγ receptors engagement. The modulation of the TME can be also achieved with immunocytokines conjugated with a mutated form of IL-2 that impairs regulatory T (Treg) cell proliferation and activity. Preclinical animal models and more recently phase I/II clinical trials have shown that IL-2 immunocytokines can avoid the severe toxicities of the systemic administration of high doses of soluble IL-2 maintaining the potent anti-tumor effect of this cytokine. Also, very promising results have been reported using IL-2 immunocytokines delivered in combination with other immunocytokines, chemo-, radio-, anti-angiogenic therapies, and blockade of immune checkpoints. Here, we summarize and discuss the most relevant reported studies with a focus on: (a) the effects of IL-2 immunocytokines on innate and adaptive anti-tumor immune cell responses as well as immunosuppressive Treg cells and (b) the approaches to circumvent IL-2-mediated severe toxic side effects.

Targeted Delivery of TNF Potentiates the Antibody-Dependent Cell-Mediated Cytotoxicity of an Anti-Melanoma Immunoglobulin

The recombinant murine IgG2a antibody TA99, directed against a melanoma antigen, was used to study combination modalities that potentiate antibody-dependent cell cytotoxicity. As previously reported, IgG2a(TA99) was extremely efficacious in preventing the growth of B16 lung metastases. However, the same antibody mediated only minimal tumor growth retardation when used to treat established neoplastic masses. The therapeutic activity of IgG2a(TA99) could be substantially enhanced by co-administration with an antibody-cytokine fusion (TA99-murine tumor necrosis factor [mTNF]), consisting of the TA99 antibody in single-chain variable fragment format fused to murine TNF. This fusion protein efficiently killed endothelial cells in vitro and displayed only minimal activity against B16 melanoma cells. In vivo, TA99-mTNF boosted the influx of natural killer cells and macrophages into B16 melanoma lesions. Therapy studies with two different administration schedules showed that the combination of TA99-mTNF and IgG2a(TA99) was superior to the individual products used as single agents. The combination treatment converted most of the tumor mass into a necrotic lesion, but a vital tumor rim eventually regrew, even when dacarbazine was included in the therapeutic regimen. The treatment modality described in this article may be applicable to the treatment of melanoma patients, given the specificity of the gp75 antigen and its conservation across species.

Pharmacokinetics and Tissue Transport of Intraperitoneal Chemotherapy

The presence of a peritoneal barrier results in a pharmacokinetic advantage associated with intraperitoneal (IP) delivery of anticancer drugs. The anticancer efficacy of IP chemotherapy depends, however, on its ability to penetrate the tumor stroma. Tumor tissue transport is governed by diffusion and convection and is affected by numerous physical, biological, and pharmaceutical variables. From preclinical and clinical studies, it appears that tissue penetration after IP chemotherapy delivery is very limited. Several approaches are studied in order to improve tissue penetration of small molecular and macromolecular anticancer drugs after IP instillation.

Reasoning the effect of immunotherapy after chemoradiation in the PACIFIC trial

Durvalumab consolidation after chemoradiation has been a giant leap in the treatment of stage III non-small-cell lung cancer with an unprecedented 16.8-month median progression-free survival. PACIFIC trial is a new foray into chemoimmunotherapy trials where we apply our knowledge of 'immunogenic cell death' and 'Abscopal' effect of radiation in the clinic. Our understanding of immunotherapy after chemoradiation treatment and application of immunogenic cell death biomarkers in future trials may be the approach we need to maximize benefit of these treatments in the appropriate patients.

Enhanced Therapeutic Activity of Non-Internalizing Small-Molecule-Drug Conjugates Targeting Carbonic Anhydrase IX in Combination with Targeted Interleukin-2

Purpose: Antibody-drug conjugates and small-molecule-drug conjugates have been proposed as alternatives to conventional anticancer cytotoxic agents, with the potential to deliver bioactive payloads to the site of disease, helping spare normal tissues.Experimental Design: Here, we describe a novel small-molecule-drug conjugate, based on a high-affinity ligand specific to carbonic anhydrase IX. The product featured a peptidic linker, suitable for cleavage in the tumor extracellular environment, and monomethyl auristatin E as cytotoxic payload.Results: A potent anticancer activity was observed in nude mice bearing SKRC-52 renal cell carcinoma xenografts, but no durable complete responses could be observed in this model. However, when the product was administered together with L19-IL2 (a clinical-stage fusion protein capable of delivering IL2 to the tumor neovasculature), all treated mice in the combination group could be rendered tumor free, in a process that favored the influx of natural killer cells into the tumor mass. The combination of L19-IL2 and the new small-molecule-drug conjugate also eradicated cancer in 100% of immunocompetent mice, bearing subcutaneously grafted CT26 colorectal cancer cells, which stably expressed carbonic anhydrase IX.Conclusions: These findings may be of clinical significance, because carbonic anhydrase IX is overexpressed in the majority of clear cell renal cell carcinomas and in approximately 30% of colorectal cancers. The targeted delivery of IL2 helps potentiate the action of targeted cytotoxics, leading to cancer eradication in models that cannot be cured by conventional chemotherapy. Clin Cancer Res; 24(15); 3656-67. ©2018 AACR.

Tumour tissue transport after intraperitoneal anticancer drug delivery

Intraperitoneal (IP) drug delivery, either as an intraoperative chemoperfusion or as an adjuvant, repeated instillation, is an established treatment modality in patients with peritoneal carcinomatosis. The efficacy of IP drugs depends on its ability to penetrate the tumour stroma in order to reach their (sub)cellular target. It is known, that drug penetration after IP delivery is limited to a few millimetres. Here, we review the basic tissue transport mechanisms after IP delivery and discuss the biophysical barriers and obstacles that limit penetration distance. In addition, we review the physical and pharmaceutical interventions that have been studied in order to improve delivery of small molecular and macromolecular drugs after IP instillation. These interventions could inform the design of future clinical trials aiming at an improved efficacy of IP-based drug delivery in carcinomatosis patients.

Targeting melanoma stem cells with the Vitamin E derivative δ-tocotrienol

The prognosis of metastatic melanoma is very poor, due to the development of drug resistance. Cancer stem cells (CSCs) may play a crucial role in this mechanism, contributing to disease relapse. We first characterized CSCs in melanoma cell lines. We observed that A375 (but not BLM) cells are able to form melanospheres and show CSCs traits: expression of the pluripotency markers SOX2 and KLF4, higher invasiveness and tumor formation capability in vivo with respect to parental adherent cells. We also showed that a subpopulation of autofluorescent cells expressing the ABCG2 stem cell marker is present in the A375 spheroid culture. Based on these data, we investigated whether δ-TT might target melanoma CSCs. We demonstrated that melanoma cells escaping the antitumor activity of δ-TT are completely devoid of the ability to form melanospheres. In contrast, cells that escaped vemurafenib treatment show a higher ability to form melanospheres than control cells. δ-TT also induced disaggregation of A375 melanospheres and reduced the spheroidogenic ability of sphere-derived cells, reducing the expression of the ABCG2 marker. These data demonstrate that δ-TT exerts its antitumor activity by targeting the CSC subpopulation of A375 melanoma cells and might represent a novel chemopreventive/therapeutic strategy against melanoma.

Potency-matched Dual Cytokine-Antibody Fusion Proteins for Cancer Therapy

A novel biopharmaceutical, consisting of the F8 mAb (specific to a splice isoform of fibronectin) simultaneously fused to both TNF and IL2, was found to react with the majority of solid tumors and hematologic malignancies in mouse and man, but not with healthy adult tissues. The product selectively localized to neoplastic lesions in vivo, as evidenced by quantitative biodistribution studies using radioiodinated protein preparations. When the potency of the cytokine payloads was matched by a single-point mutation, the resulting fusion protein (IL2-F8-TNFmut) eradicated soft-tissue sarcomas in immunocompetent mice, which did not respond to individual antibody-cytokine fusion proteins or by standard doxorubicin treatment. Durable complete responses were also observed in mice bearing CT26, C1498, and F9 tumors. The simultaneous delivery of multiple proinflammatory payloads to the cancer site conferred protective immunity against subsequent tumor challenges. A fully human homolog of IL2-F8-TNFmut, which retained selectivity similar to its murine counterpart when tested on human material, may open new clinical applications for the immunotherapy of cancer. Mol Cancer Ther; 16(11); 2442-51. ©2017 AACR.

Targeted Delivery of Cytotoxic Drugs: Challenges, Opportunities and New Developments

Cytotoxic drugs, which are commonly used for the pharmacotherapy of many forms of cancer, often cause substantial toxicity to the patient without being able to induce long-lasting remissions. Ligands specific to accessible tumor-associated targets, capable of selective localization at the neoplastic site, may facilitate the preferential delivery of anti-cancer drugs, boosting activity and helping spare normal organs. In this article, we present a critical analysis of the limitation of conventional anti-cancer drugs and we contrast monoclonal antibodies and small organic ligands, as vehicles for pharmacodelivery applications.

Tumor-targeted IL-12 combined with local irradiation leads to systemic tumor control via abscopal effects in vivo

NHS-IL12 is an immunocytokine, a fusion protein of IL12's functional domains and a necrosis-targeting antibody, which has shown significant effects against human rhabdomyosarcoma xenografts in a humanized tumor model, including terminal growth arrest and differentiation of the tumor cells. Here, we locally irradiated the tumors, increasing necrosis and consequently intratumoral immune cytokine availability, and asked whether this effect may surmount efficacy of single treatment modality. Humanized mice bearing bilateral rhabdomyosarcoma xenografts were evaluated for tumor burden and survival after irradiation, systemic NHS-IL12 therapy or a combination of both. Intratumoral immune compartments were characterized by immunohistochemistry and molecular methods. T_H1-cytokine dependency of underlying effector mechanisms were investigated in vitro in several human tumor cell lines. NHS-IL12 when combined with irradiation terminally arrested tumor growth and significantly improved survival. Combination treatment induced dense intratumoral T-cell infiltrates, clonal epitope-specific T-cell expansions, expression of cytotoxins, decreased pro-tumorigenic cytokines and induced senescence and differentiation in the cancer cells. Senescence and differentiation were reproduced in vitro and confirmed to be dependent on T_H1 cytokines IFNγ and TNF-α. NHS-IL12 and irradiation together induced broad intratumoral T_H1 biased NK and T-cell compartments, established antitumoral cytokine profiles and irreversibly growth arrested tumor cells, leading to systemic cancer control and improved survival. For the first time, we describe immune-induced senescence as a novel mechanism resulting from a treatment regimen combining irradiation with immunotherapy.

Class II phosphoinositide 3-kinase C2β regulates a novel signaling pathway involved in breast cancer progression

It is now well established that the enzymes phosphoinositide 3-kinases (PI3Ks) have a key role in the development and progression of many cancer types and indeed PI3Ks inhibitors are currently being tested in clinical trials. Although eight distinct PI3K isoforms exist, grouped into three classes, most of the evidence currently available are focused on one specific isoform with very little known about the potential role of the other members of this family in cancer. Here we demonstrate that the class II enzyme PI3K-C2β is overexpressed in several human breast cancer cell lines and in human breast cancer specimens. Our data indicate that PI3K-C2β regulates breast cancer cell growth in vitro and in vivo and that PI3K-C2β expression in breast tissues is correlated with the proliferative status of the tumor. Specifically we show that downregulation of PI3K-C2β in breast cancer cell lines reduces colony formation, induces cell cycle arrest and inhibits tumor growth, in particular in an estrogen-dependent in vivo xenograft. Investigation of the mechanism of the PI3K-C2β-dependent regulation of cell cycle progression and cell growth revealed that PI3K-C2β regulates cyclin B1 protein levels through modulation of microRNA miR-449a levels. Our data further demonstrate that downregulation of PI3K-C2β inhibits breast cancer cell invasion in vitro and breast cancer metastasis in vivo. Consistent with this, PI3K-C2β is highly expressed in lymph-nodes metastases compared to matching primary tumors. These data demonstrate that PI3K-C2β plays a pivotal role in breast cancer progression and in metastasis development. Our data indicate that PI3K-C2β may represent a key molecular switch that regulates a rate-limiting step in breast tumor progression and therefore it may be targeted to limit breast cancer spread.

Targeting Fibronectin for Cancer Imaging and Therapy

During cancer progression, the extracellular matrix (ECM) undergoes dramatic changes, which promote cancer cell migration and invasion. In the remodeled tumor ECM, fibronectin (FN) level is upregulated to assist tumor growth, progression, and invasion. FN serves as a central organizer of ECM molecules and mediates the crosstalk between the tumor microenvironment and cancer cells. Its upregulation is correlated with angiogenesis, cancer progression, metastasis, and drug resistance. A number of FN-targeting ligands have been developed for cancer imaging and therapy. Thus far, FN-targeting imaging agents have been tested for nuclear imaging, MRI, and fluorescence imaging, for tumor detection and localization. FN-targeting therapeutics, including nuclear medicine, chemotherapy drugs, cytokines, and photothermal moieties, were also developed in cancer therapy. Because of the prevalence of FN overexpression in cancer, FN targeting imaging agents and therapeutics have the promise of broad applications in the diagnosis, treatment, and image-guided interventions of many types of cancers. This review will summarize current understanding on the role of FN in cancer, discuss the design and development of FN-targeting agents, and highlight the applications of these FN-targeting agents in cancer imaging and therapy.

Immunocytokines and bispecific antibodies: two complementary strategies for the selective activation of immune cells at the tumor site

The activation of the immune system for a selective removal of tumor cells represents an attractive strategy for the treatment of metastatic malignancies, which cannot be cured by existing methodologies. In this review, we examine the design and therapeutic potential of immunocytokines and bispecific antibodies, two classes of bifunctional products which can selectively activate the immune system at the tumor site. Certain protein engineering aspects, such as the choice of the antibody format, are common to both classes of therapeutic agents and can have a profound impact on tumor homing performance in vivo of individual products. However, immunocytokines and bispecific antibodies display different mechanisms of action. Future research activities will reveal whether an additive of even synergistic benefit can be obtained from the judicious combination of these two types of biopharmaceutical agents.

Fusion cytokine IL-2-GMCSF enhances anticancer immune responses through promoting cell-cell interactions

Background

Potent antitumor responses can be induced through cytokine immunotherapy. Interleukin (IL)-2 and granulocyte–macrophage colony-stimulating factor (GM-CSF) are among the most effective cytokines to induce tumor-specific systemic immune responses and can act synergistically. To overcome the limitations of combined use of these two cytokines, we have constructed an IL2-GMCSF fusion protein and characterized its antitumor effects in this study.

Methods

The expression of IL-2 receptor and GM-CSF receptor of cell lines were detected with quantitative real-time PCR. On this basis, the bioactivities of IL2-GMCSF, especially effects on DC2.4 cells were assayed. Another function of IL2-GMCSF—bridge two types of cells—was assessed by cell contact counting and cytotoxicity assays. The anti-tumor activity in vivo of IL2-GMCSF was evaluated in the melanoma model. The statistical significance among treatment groups were determined by One-Way ANOVA.

Results

The fusion protein IL2-GMCSF maintained the activities of IL-2 and GM-CSF, and could significantly promote DC2.4 cell activities, including phagocytosis, proliferation and cytokine secretion. In addition to the inherent cytokine activity, IL2-GMCSF bridges direct cell–cell interactions and enhances splenocyte killing efficacy against multiple tumor cell lines in vitro. Co-injection of IL2-GMCSF and inactivated B16F10 mouse melanoma cells induced complete immunoprotective responses in about 30 % of mice.

Conclusion

These results suggested that IL2-GMCSF can efficiently regulate immune responses against tumors. Furthermore, as the bridging effect relies on both IL-2R and GM-CSFR and promotes interactions between immune and tumor cells, IL2-GMCSF may be utilized as a useful tool for dissecting specific immune responses for future clinical applications.

Fibronectin-targeted drug delivery in cancer

Fibronectin is an extracellular matrix protein with pivotal physiological and pathological functions in development and adulthood. Alternative splicing of the precursor mRNA, produced from the single copy fibronectin gene, occurs at three sites coding for the EDA, EDB and IIICS domains. Fibronectin isoforms comprising the EDA or EDB domains are known as oncofetal forms due to their developmental importance and their re-expression in tumors, contrasting with restricted presence in normal adult tissues. These isoforms are also recognized as important markers of angiogenesis, a crucial physiological process in development and required by tumor cells in cancer progression. Attributed to this feature, EDA and EDB domains have been extensively used for the targeted delivery of cytokines, cytotoxic agents, chemotherapy drugs and radioisotopes to fibronectin-expressing tumors to exert therapeutic effects on primary cancers and metastatic lesions. In addition to drug delivery, the EDA and EDB domains of fibronectin have also been utilized to develop imaging strategies for tumor tissues. Furthermore, EDA and EDB based vaccines seem to be promising for the treatment and prevention of certain cancer types. In this review, we will summarize recent advances in fibronectin EDA and EDB-based therapeutic strategies developed to treat cancer.

Therapeutic vaccination against fibronectin ED-A attenuates progression of metastatic breast cancer

Therapeutic vaccination targeting self-molecules is an attractive alternative to monoclonal antibody-based therapies for cancer and various inflammatory diseases. However, development of cancer vaccines targeting self-molecules has proven difficult. One complicating factor is that tumor cells have developed strategies to escape recognition by the immune system. Antigens specifically expressed by the tumor vasculature can therefore provide alternative targets. The alternatively spliced extra domain-A and B (ED-A and ED-B) of fibronectin are expressed during vasculogenesis in the embryo, but essentially undetectable under normal conditions in the adult. However, these domains are re-expressed during tumor angiogenesis and matrix remodeling, which renders them highly interesting for targeted cancer therapies.

Using the MMTV-PyMT transgenic model of metastatic mammary carcinoma, we show that tumor burden can be significantly decreased by immunization against ED-A in a therapeutic setting. Furthermore, we found that in mice carrying anti-ED-A antibodies the number of metastases was reduced. ED-A immunization increased infiltration of macrophages and compromised tumor blood vessel function. These findings implicate an attack of the tumor vasculature by the immune system, through a polyclonal antibody response. We conclude that tumor vascular antigens are promising candidates for development of therapeutic vaccines targeting growth of primary tumors as well as disseminated disease.

Nanoparticle-mediated drug delivery for treating melanoma

Melanoma originated from melanocytes is the most aggressive type of skin cancer with limited treatment options. New targeted therapeutic options with the discovery of BRAF and MEK inhibitors have shown significant survival benefits. Despite the recent progress, development of chemoresistance and systemic toxicity remains a challenge for treating metastatic melanoma. While the response from the first line of treatment against melanoma using dacarbazine remains only 5-10%, the prolonged use of targeted therapy against mutated oncogene BRAF develops chemoresistance. In this review, we will discuss the nanoparticle-based strategies for encapsulation and conjugation of drugs to the polymer for maximizing their tumor distribution through enhanced permeability and retention effect. We will also highlight photodynamic therapy and design of melanoma-targeted nanoparticles.

Estrogen Receptor β Agonists Differentially Affect the Growth of Human Melanoma Cell Lines

Background

Cutaneous melanoma is an aggressive malignancy; its incidence is increasing worldwide and its prognosis remains poor. Clinical observations indicate that estrogen receptor β (ERβ) is expressed in melanoma tissues and its expression decreases with tumor progression, suggesting its tumor suppressive function. These experiments were performed to investigate the effects of ERβ activation on melanoma cell growth.

Methods and Results

Protein expression was analyzed by Western blot and immunofluorescence assays. Cell proliferation was assessed by counting the cells by hemocytometer. ERβ transcriptional activity was evaluated by gene reporter assay. Global DNA methylation was analyzed by restriction enzyme assay and ERβ isoforms were identified by qRT-PCR. We demonstrated that ERβ is expressed in a panel of human melanoma cell lines (BLM, WM115, A375, WM1552). In BLM (NRAS-mutant) cells, ERβ agonists significantly and specifically inhibited cell proliferation. ERβ activation triggered its cytoplasmic-to-nuclear translocation and transcriptional activity. Moreover, the antiproliferative activity of ERβ agonists was associated with an altered expression of G1-S transition-related proteins. In these cells, global DNA was found to be hypomethylated when compared to normal melanocytes; this DNA hypomethylation status was reverted by ERβ activation. ERβ agonists also decreased the proliferation of WM115 (BRAF V600D-mutant) cells, while they failed to reduce the growth of A375 and WM1552 (BRAF V600E-mutant) cells. Finally, we could observe that ERβ isoforms are expressed at different levels in the various cell lines. Specific oncogenic mutations or differential expression of receptor isoforms might be responsible for the different responses of cell lines to ERβ agonists.

Conclusions

Our results demonstrate that ERβ is expressed in melanoma cell lines and that ERβ agonists differentially regulate the proliferation of these cells. These data confirm the notion that melanoma is a heterogeneous tumor and that genetic profiling is mandatory for the development of effective personalized therapeutic approaches for melanoma patients.

Therapeutic vaccination targeting the tumour vasculature

Therapeutic vaccination targeting self-molecules could provide a cost-efficient alternative to monoclonal antibody-based therapies for cancer and various inflammatory diseases. However, development of cancer vaccines targeting self-molecules has proven difficult. One complicating factor is that tumour cells have developed strategies to escape recognition by the immune system. Antigens specifically expressed by the tumour vasculature can therefore provide alternative targets. The present mini-review highlights potential target molecules associated with tumour angiogenesis and the approaches made to direct an immune response against them. Furthermore, the requirements on a vaccine targeting self-molecules, in contrast with those directed against virus or bacteria, are discussed.

Antibody fusions with immunomodulatory proteins for cancer therapy

The potential of immunomodulatory proteins, in particular cytokines, for cancer therapy is well recognized, but hampered by the toxicity associated with their systemic application. In order to address this problem, targeted delivery by antibody fusion proteins has been early proposed and their development intensively pursued over the last decade. Here, factors influencing the selection and modification of cytokines and antibody formats for this approach are being discussed, indicating current developments and translational advances in the field.

Combination of radiotherapy with the immunocytokine L19-IL2: Additive effect in a NK cell dependent tumour model

BACKGROUND AND PURPOSE

Recently, we have shown that radiotherapy (RT) combined with the immunocytokine L19-IL2 can induce long-lasting antitumour effects, dependent on ED-B expression and infiltration of cytotoxic T cells. On the other hand, in certain tumours, IL2 treatment can trigger a natural killer cell (NK) immune response. The aim of this study is to investigate the therapeutic effect of our combination therapy in the ED-B positive F9 teratocarcinoma model, lacking MHCI expression and known to be dependent on NK immune responses.

MATERIAL AND METHODS

In syngeneic F9 tumour bearing 129/FvHsd mice tumour growth delay was evaluated after local tumour irradiation (10Gy) combined with systemic administration of L19-IL2. Immunological responses were investigated using flow cytometry.

RESULTS

Tumour growth delay of L19-IL2 can be further improved by a single dose of RT administered before immunotherapy, but not during immunotherapy. Furthermore, treatment of L19-IL2 favours a NK response and lacks cytotoxic T cell tumour infiltrating immune cells, which may be explained by the absence of MHCI expression.

CONCLUSION

An additive effect can be detected when the NK dependent F9 tumour model is treated with radiotherapy and L19-IL2 and therefore this combination could be useful in the absence of tumoural MHCI expression.

The antibody-mediated targeted delivery of interleukin-13 to syngeneic murine tumors mediates a potent anticancer activity

We describe the expression and in vivo characterization of an antibody-cytokine fusion protein, based on murine Interleukin-13 (IL13) and the monoclonal antibody F8, specific to the alternatively spliced extra domain A of fibronectin, a marker of neo-angiogenesis. The IL13 moiety was fused at the C-terminal extremity of the F8 antibody in diabody format. The resulting F8-IL13 immunocytokine retained the full binding properties of the parental antibody and cytokine bioactivity. The fusion protein could be expressed in mammalian cells, purified to homogeneity and showed a preferential accumulation at the tumor site. When used as single agent at doses of 200 μg, F8-IL13 exhibited a strong inhibition of tumor growth rate in two models of cancer (F9 teratocarcinoma and Wehi-164), promoting an infiltration of various types of leukocytes into the neoplastic mass. This anticancer activity could be potentiated by combination with an immunocytokine based on the F8 antibody and murine IL12, leading to complete and long-lasting tumor eradications. Mice cured from Wehi-164 sarcomas acquired a durable protective antitumor immunity, and selective depletion of immune cells revealed that the antitumor activity was mainly mediated by cluster of differentiation 4-positive T cells. This study indicates that IL13 can be efficiently delivered to the tumor neo-vasculature and that it mediates a potent anticancer activity in the two models of cancer investigated in this study. The observed mechanism of action for F8-IL13 was surprising, since immunocytokines based on other payloads (e.g., IL2, IL4, IL12 and TNF) eradicate cancer by the combined contribution of natural killer cells and cluster of differentiation 8-positive T cells.