The immunocytokine L19-IL2 eradicates cancer when used in combination with CTLA-4 blockade or with L19-TNF

Effective Combination of Innate and Adaptive Immunotherapeutic Approaches in a Mouse Melanoma Model

Most cancer immunotherapies include activation of either innate or adaptive immune responses. We hypothesized that the combined activation of both innate and adaptive immunity will result in better antitumor efficacy. We have previously shown the synergy of an agonistic anti-CD40 mAb (anti-CD40) and CpG-oligodeoxynucleotides in activating macrophages to induce tumor cell killing in mice. Separately, we have shown that a direct intratumoral injection of immunocytokine (IC), an anti-GD2 Ab linked to IL-2, can activate T and NK cells resulting in antitumor effects. We hypothesized that activation of macrophages with anti-CD40/CpG, and NK cells with IC, would cause innate tumor destruction, leading to increased presentation of tumor Ags and adaptive T cell activation; the latter could be further augmented by anti-CTLA-4 Ab to achieve tumor eradication and immunological memory. Using the mouse GD2⁺ B78 melanoma model, we show that anti-CD40/CpG treatment led to upregulation of T cell activation markers in draining lymph nodes. Anti-CD40/CpG + IC/anti-CTLA-4 synergistically induced regression of advanced s.c. tumors, resulting in cure of some mice and development of immunological memory against B78 and wild type B16 tumors. Although the antitumor effect of anti-CD40/CpG did not require T cells, the antitumor effect of IC/anti-CTLA-4 was dependent on T cells. The combined treatment with anti-CD40/CpG + IC/anti-CTLA-4 reduced T regulatory cells in the tumors and was effective against distant solid tumors and lung metastases. We suggest that a combination of anti-CD40/CpG and IC/anti-CTLA-4 should be developed for clinical testing as a potentially effective novel immunotherapy strategy.

Therapeutic efficacy of an anti-PD-L1 antibody based immunocytokine in a metastatic mouse model of colorectal cancer

Immunocytokines (antibody-cytokine fusions) have been proved to be a promising class of therapeutic agents for tumors. Anti-PD-L1 antibodies or IL-2 have been used to treat a variety of cancers. Here, in order to remove T cell inhibition and increasing the IL-2 concentration in the tumor microenvironment, we engineered a novel anti-PD-L1 antibody based immunocytokine by fusing hIL-2 to the C-Term of atezolizumab, denoted as BIPI. Our results revealed that BIPI was effective in stimulating T cell activation in vitro and could selectively localize to the tumor. Furthermore, tumor regression and prolonged survival were also observed in the metastatic colorectal cancer mouse model. The obviously longer survival mice in BIPI treatment group turned out depending on the function of CD8⁺ T cells. The IFN- secreted from CD8⁺ T cells in the spleen also contributed to the better tumor inhibition profile in BIPI treatment group than in anti-PD-L1 or IL-2 treatment alone. Taken together, our data evidenced the enhanced antitumor potency of BIPI, suggesting its potential use for cancers with a low response to the anti-PD-L1 or IL-2 treatment.

Immunocytokines for cancer treatment: past, present and future

Immunocytokines are antibody-cytokine fusion proteins, with the potential to preferentially localize on tumor lesions and to activate anticancer immunity at the site of disease. Various tumor targets (e.g., cell membrane antigens and extracellular matrix components) and antibody formats (e.g., intact IgG and antibody fragments) have been considered for immunocytokine development and some products have advanced to clinical trials. In this review, we present relevant concepts and strategies for the design and use of anticancer immunocytokine products. In addition, we discuss emerging strategies for the pharmaceutical development and clinical application of this promising class of biopharmaceuticals.

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.

Angiogenesis in melanoma: an update with a focus on current targeted therapies

Angiogenesis plays a crucial role in melanoma metastasis and progression. In recent years, numerous studies have investigated the prognostic and clinical significance of this phenomenon, and the development of molecular techniques has enabled us to achieve a better understanding of angiogenesis in melanoma. Herein, we review the current state of knowledge regarding angiogenesis in melanoma, including the pathophysiological, histological and immunohistochemical aspects of this phenomenon. We also review the molecular pathways involved in angiogenesis and the interplay between different components that might be manipulated in the future development of efficient targeted therapies. Recently developed targeted antiangiogenic therapies in clinical trials and included in the treatment of advanced-stage melanoma are also reviewed.

Going with the flow: harnessing the power of the vasculature for targeted therapy in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disease that leads to excessive joint inflammation and is associated with significant morbidity and mortality. Although much is still to be learned about the aetiology RA, a growing body of evidence suggests that an altered vascular environment is an important aspect of its pathophysiology. In this context, RA shares many similarities with cancer, and it is expected that several angiogenic targets in cancer might be relevant to the treatment of RA. Here, we discuss how these targets can be combined with advances in drug development to generate the next generation of RA therapeutics.

Intralesional administration of L19-IL2/L19-TNF in stage III or stage IVM1a melanoma patients: results of a phase II study

The intratumoral injection of cytokines, in particular IL2, has shown promise for cutaneous melanoma patients with unresectable disease or continuous recurrence despite surgery. We recently reported that the intralesional injection of L19-IL2, an immunocytokine combining IL2 and the human monoclonal antibody fragment L19, resulted in efficient regional control of disease progression, increased time to distant metastasis and evidence of effect on circulating immune cell populations. We have also shown in preclinical models of cancer a remarkable synergistic effect of the combination of L19-IL2 with L19-TNF, a second clinical-stage immunocytokine, based on the same L19 antibody fused to TNF. Here, we describe the results of a phase II clinical trial based on the intralesional administration of L19-IL2 and L19-TNF in patients with stage IIIC and IVM1a metastatic melanoma, who were not candidate to surgery. In 20 efficacy-evaluable patients, 32 melanoma lesions exhibited complete responses upon intralesional administration of the two products, with mild side effects mainly limited to injection site reactions. Importantly, we observed complete responses in 7/13 (53.8 %) non-injected lesions (4 cutaneous, 3 lymph nodes), indicating a systemic activity of the intralesional immunostimulatory treatment. The intralesional administration of L19-IL2 and L19-TNF represents a simple and effective method for the local control of inoperable melanoma lesions, with a potential to eradicate them or make them suitable for a facile surgical removal of the residual mass.

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.

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.

Armed antibodies for cancer treatment: a promising tool in a changing era

Advances in the understanding of tumor immunology and molecular biology of melanoma cells have favored a larger application of immunotherapy and targeted therapies in the clinic. Several selective mutant gene inhibitors and immunomodulating antibodies have been reported to improve overall survival or progression-free survival in metastatic melanoma patients. However, despite impressive initial responses, patients treated with selective inhibitors relapse quickly, and toxicities associated to the use of immunomodulating antibodies are not easily manageable. In this sense, the concept of using antibodies as delivery vehicles for the preferential in vivo localization of the drug at the site of disease with reduction of side effects has raised particular interest. Antibody-cytokine fusion proteins (termed immunocytokines) represent a new simple and effective way to deliver the immunomodulatory payload at the tumor site, with the aim of inducing both local and systemic antitumoral immune responses and limiting systemic toxicities. Several clinical trials have been conducted and are actually ongoing with different immunocytokines, in several tumor histotypes. In metastatic melanoma patients, different drug delivery modalities such as systemic, loco-regional and intratumoral are under investigation. In this review, the rationale for the use of L19-IL2 and L19-TNF, two clinical stage immunocytokines produced by the Philogen group, as well as opportunities for their future development will be discussed.

A chemically defined trifunctional antibody-cytokine-drug conjugate with potent antitumor activity

The combination of immunostimulatory agents with cytotoxic drugs is emerging as a promising approach for potentially curative tumor therapy, but advances in this field are hindered by the requirement of testing individual combination partners as single agents in dedicated clinical studies, often with suboptimal efficacy. Here, we describe for the first time a novel multipayload class of targeted drugs, the immunocytokine-drug conjugates (IDC), which combine a tumor-homing antibody, a cytotoxic drug, and a proinflammatory cytokine in the same molecular entity. In particular, the IL2 cytokine and the disulfide-linked maytansinoid DM1 microtubular inhibitor could be coupled to the F8 antibody, directed against the alternatively spliced EDA domain of fibronectin, in a site-specific manner, yielding a chemically defined product with selective tumor-homing performance and potent anticancer activity in vivo, as tested in two different immunocompetent mouse models.

Preclinical evaluation of IL2-based immunocytokines supports their use in combination with dacarbazine, paclitaxel and TNF-based immunotherapy

Antibody-cytokine fusion proteins ("immunocytokines") represent a promising class of armed antibody products, which allow the selective delivery of potent pro-inflammatory payloads at the tumor site. The antibody-based selective delivery of interleukin-2 (IL2) is particularly attractive for the treatment of metastatic melanoma, an indication for which this cytokine received marketing approval from the US Food and drug administration. We used the K1735M2 immunocompetent syngeneic model of murine melanoma to study the therapeutic activity of F8-IL2, an immunocytokine based on the F8 antibody in diabody format, fused to human IL2. F8-IL2 was shown to selectively localize at the tumor site in vivo, following intravenous administration, and to mediate tumor growth retardation, which was potentiated by the combination with paclitaxel or dacarbazine. Combination treatment led to a substantially more effective tumor growth inhibition, compared to the cytotoxic drugs used as single agents, without additional toxicity. Analysis of the immune infiltrate revealed a significant accumulation of CD4(+) T cells 24 h after the administration of the combination. The fusion proteins F8-IL2 and L19-IL2, specific to the alternatively spliced extra domain A and extra domain B of fibronectin respectively, were also studied in combination with tumor necrosis factor (TNF)-based immunocytokines. The combination treatment was superior to the action of the individual immunocytokines and was able to eradicate neoplastic lesions after a single intratumoral injection, a procedure that is being clinically used for the treatment of Stage IIIC melanoma. Collectively, these data reinforce the rationale for the use of IL2-based immunocytokines in combination with cytotoxic agents or TNF-based immunotherapy for the treatment of melanoma patients.

Antibody-mediated delivery of interleukin 4 to the neo-vasculature reduces chronic skin inflammation

BACKGROUND

The antibody-mediated delivery of cytokines ("immunocytokines") to sites of pathological angiogenesis represents an attractive strategy for the development of innovative biopharmaceuticals, capable of modulating the activity of the immune system in cancer and in chronic inflammatory conditions.

OBJECTIVE

Recombinant IL4 has previously been shown to be therapeutically active in patients with psoriasis. The antibody-mediated delivery of this cytokine to sites of chronic skin inflammatory conditions should lead to an improved potency and selectivity, compared to non-targeted IL4.

METHODS

The therapeutic activity of F8-IL4, a fusion protein of the F8 antibody (specific to the alternatively-spliced EDA domain of fibronectin) with murine IL4, was investigated in three immunocompetent mouse models of skin inflammation: two induced by the TLR7/8 ligand imiquimod (in Balb/c and C57BL/6) and one mediated by the over-expression of VEGF-A.

RESULTS

The EDA domain of fibronectin, a marker for angiogenesis, is expressed in the inflamed skin in all three models and F8-IL4 selectively localized to inflamed skin lesions following intravenous administration. The F8-IL4 fusion protein mediated a therapeutic benefit, which was superior to the one of a non-targeted version of IL4 and led to increased levels of key regulatory cytokines (including IL5, IL10, IL13, and IL27) in the inflamed skin, while IL2 levels were not affected in all treatment groups. A murine version of etanercept and a murine anti-IL17 antibody were used as positive control in the therapy experiments.

CONCLUSION

Skin inflammatory lesions can be selectively targeted using anti-EDA antibody-cytokine fusion proteins and the pharmacodelivery of IL4 confers a therapeutic benefit by shifting the cytokine balance.

Antibody-cytokine fusion proteins for treatment of cancer: engineering cytokines for improved efficacy and safety

The true potential of cytokine therapies in cancer treatment is limited by the inability to deliver optimal concentrations into tumor sites due to dose-limiting systemic toxicities. To maximize the efficacy of cytokine therapy, recombinant antibody-cytokine fusion proteins have been constructed by a number of groups to harness the tumor-targeting ability of monoclonal antibodies. The aim is to guide cytokines specifically to tumor sites where they might stimulate more optimal anti-tumor immune responses while avoiding the systemic toxicities of free cytokine therapy. Antibody-cytokine fusion proteins containing interleukin (IL)-2, IL-12, IL-21, tumor necrosis factor (TNF)α, and interferons (IFNs) α, β, and γ have been constructed and have shown anti-tumor activity in preclinical and early-phase clinical studies. Future priorities for development of this technology include optimization of tumor targeting, bioactivity of the fused cytokine, and choice of appropriate agents for combination therapies. This review is intended to serve as a framework for engineering an ideal antibody-cytokine fusion protein, focusing on previously developed constructs and their clinical trial results.

Specificity delivers: therapeutic role of tumor antigen-specific antibodies in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is among the most deadly cancers with less than 5% of the patients living beyond 5 years post-diagnosis. Lack of early diagnostic biomarkers and resistance to current therapies help explain these disappointing numbers. Thus, more effective and better-targeted therapies are needed quickly. Monoclonal antibodies offer an attractive alternative targeted therapy option for PDA because they are highly specific and potent. However, currently available monoclonal antibody therapies for PDA are still in their infancy with a low success rate and low likelihood of being approved. The challenges faced by these therapies include the following: lack of predictive and response biomarkers, unfavorable safety profiles, expression of targets not restricted to the cancer cells, flawed preclinical model systems, drug resistance, and PDA's complex nature. Additionally, discovery of novel PDA-specific antigen targets, present on the cell surface or in the extracellular matrix, is needed. Predictive and response markers also need to be determined for PDA patient subgroups so that the most appropriate effective therapy can be delivered. Serologic approaches, recombinant antibody-producing technologies, and advances in antibody engineering techniques will help to identify these predictive biomarkers and aid in the development of new therapeutic antibodies. A combinatorial approach simultaneously targeting antigens on the PDA cell, stroma, and immunosuppressive cells should be employed.

Genetically engineered Newcastle disease virus expressing interleukin-2 and TNF-related apoptosis-inducing ligand for cancer therapy

Recombinant Newcastle disease virus (rNDV) have shown oncolytic therapeutic efficacy in preclinical studies and are currently in clinical trials. In this study, we have evaluated the possibility to enhance the cancer therapeutic potential of NDV by means of inserting both interleukin-2 (IL-2) and tumor necrosis factor-related apoptosis inducing ligand (TRAIL) delivered by rNDV. We demonstrated that rNDV expressing TRAIL (rNDV-TRAIL) or both human IL-2 and TRAIL (rNDV-IL-2-TRAIL) significantly enhanced inherent anti-neoplastic of rNDV by inducing apoptosis. And we showed that apoptosis-related genes mRNA expression was increased after treated with rNDV-TRAIL or rNDV-IL-2-TRAIL compared with rNDV and rNDV-IL-2. We also demonstrated that both rNDV-IL-2 and rNDV-IL-2-TRAIL induced proliferation of the CD4(+) and CD8(+) in treated mice and elicited expression of TNF-α and IFN-γ antitumor cytokines. These mice treated with oncolytic agents exhibited significant reduction in tumor development compared with mice treated with the parental virus. In addition, experiments in both hepatocellular carcinoma and melanoma-bearing mice demonstrated that the genetically engineered rNDV-IL-2-TRAIL exhibited prolonged animals' survival compared with rNDV, rNDV-IL-2, and rNDV-TRAIL. In conclusion, the immunotherapy and oncolytic virotherapy properties of NDV can be enhanced by the introduction of IL-2 and TRAIL genes, whose products initiated a broad cascade of immunological affects and induced tumor cells apoptosis in the microenvironment of the immune system.

The dose-dependent tumor targeting of antibody-IFNγ fusion proteins reveals an unexpected receptor-trapping mechanism in vivo

Cytokines often display substantial toxicities at low concentrations, preventing their escalation for therapeutic treatment of cancer. Fusion proteins comprising cytokines and recombinant antibodies may improve the anticancer activity of proinflammatory cytokines. Murine IFNγ was appended in the diabody format at the C-terminus of the F8 antibody, generating the F8-IFNγ fusion protein. The F8 antibody is specific for the extra-domain A (EDA) of fibronectin, a tumor-associated antigen that is expressed in the vasculature and stroma of almost all tumor types. Tumor-targeting properties were measured in vivo using a radioiodinated preparation of the fusion protein. Therapy experiments were performed in three syngeneic murine models of cancer [F9 teratocarcinoma, WEHI-164 fibrosarcoma, and Lewis lung carcinoma (LLC)]. F8-IFNγ retained the biologic activity of both the antibody and the cytokine moiety in vitro, but, unlike the parental F8 antibody, it did not preferentially localize to the tumors in vivo. However, when unlabeled F8-IFNγ was administered before radioiodinated F8-IFNγ, a selective accumulation at the tumor site was observed. F8-IFNγ showed dose-dependent anticancer activity with a clear superiority over untargeted recombinant IFNγ. The anticancer activity was potentiated by combining with F8-IL4 without additional toxicities, whereas combination of F8-IFNγ with F8-TNF was lethal in all mice. Unlike other antibody-cytokine fusions, the use of IFNγ as payload for anticancer therapy is associated with a receptor-trapping mechanism, which can be overcome by the administration of a sufficiently large amount of the fusion protein without any detectable toxicity at the doses used.

Tumor-targeting properties of novel immunocytokines based on murine IL1β and IL6

There is an increasing biotechnological interest in 'arming' therapeutic antibodies with bioactive payloads. Many antibody-cytokine fusion proteins (immunocytokines) have been described and some of these biopharmaceuticals have progressed to clinical studies. Here, we describe for the first time the expression and in vivo characterization of immunocytokines based on murine IL1β and IL6. These potent pro-inflammatory cytokines were fused at the N-terminus or at the C-terminus of the monoclonal antibodies F8 (specific to the alternatively-spliced extra-domain A domain of fibronectin, a marker of tumor angiogenesis). All immunocytokines retained the binding properties of the parental antibody and were homogenous, when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, except for the N-terminal fusion of IL1β which revealed the presence of glycosylated species. When analyzed by quantitative biodistribution analysis using radioiodinated protein preparations, F8 fusions with IL6 revealed a preferential accumulation at the tumor site for both cytokine orientations, whereas IL1β fusions exhibited lower tumor to organ ratios and a slower blood clearance profile. The fusion proteins with the cytokine payload at the C-terminus were studied in therapy experiments in immunocompetent mice bearing F9 tumors. Immunocytokines based on IL1β resulted in 10% body weight loss at a 5-µg dose, whereas IL6-based products caused a 5% body weight loss at a 225-µg dose. Both F8-IL1β and F8-IL6 exhibited a <50% inhibition of tumor growth rate, which was substantially lower than the one previously reported for F8-TNF, a closely related pro-inflammatory immunocytokine. This study indicates that IL6 can be efficiently delivered to the tumor neo-vasculature by fusion with the F8 antibody. While F8-IL6 was not as potent as other F8-based immunocytokines that exhibit similar biodistribution profiles, the fusion protein sheds light on the different roles of pro-inflammatory cytokines in boosting immunity against the tumor.

Intralesional treatment of stage III metastatic melanoma patients with L19-IL2 results in sustained clinical and systemic immunologic responses

L19-IL2 is a recombinant protein comprising the cytokine IL2 fused to the single-chain monoclonal antibody L19. In previous studies, intralesional injection with IL2 has shown efficacy for the locoregional treatment of cutaneous/subcutaneous metastases in patients with advanced melanoma. The objectives of this study were to investigate whether (i) intralesional delivery of a targeted form of IL2 would yield similar results, with reduction of injection frequency and treatment duration; and (ii) systemic immune responses were induced by the local treatment. Patients with stage IIIB/IIIC melanoma and cutaneous/subcutaneous injectable metastases received weekly intratumoral injections of L19-IL2 at a maximum dose of 10 MIU/week for 4 consecutive weeks. Tumor response was evaluated 12 weeks after the first treatment. Twenty-four of 25 patients were evaluable for therapy-induced responses. A complete response (CR) by modified immune-related response criteria (irRC) of all treated metastases was achieved in 6 patients (25%), with long-lasting responses in most cases (5 patients for ≥24 months). Objective responses were documented in 53.9% of all index lesions [44.4% CR and 9.5% partial responses (by irRC)], and 36.5% of these remained stable, while 9.5% progressed. Toxicity was comparable with that of free IL2, and no serious adverse events were recorded. A significant temporary increase of peripheral regulatory T cells and natural killer cells, sustained increase of absolute CD4(+) lymphocytes, and decrease of myeloid-derived suppressor cells were observed upon treatment. Finally, we recorded encouraging data about the progression time to distant metastases and overall survival.

Challenging resistance mechanisms to therapies for metastatic melanoma

Melanoma is the most aggressive form of skin cancer and, if spread outside the epidermis, has a dismal prognosis. Before the approval of the anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) monoclonal antibody ipilimumab and the BRAF inhibitors vemurafenib and dabrafenib, no other agents had demonstrated better results in terms of overall survival than the DNA-methylating compound dacarbazine (or its oral analog temozolomide). However, most patients with metastatic melanoma do not obtain long-lasting clinical benefit from ipilimumab and responses to BRAF inhibitors are short lived. Thus, combination therapies with inhibitors of DNA repair (e.g., poly(ADP-ribose) polymerase [PARP] inhibitors), novel immunomodulators (monoclonal antibodies against programmed death-1 [PD-1] or its ligand PD-L1), targeted therapies (mitogen-activated protein kinase [MAPK]/extracellular signal-regulated kinase [ERK] kinase [MEK] or phosphatidylinositol 3-kinase [PI3K]/AKT/mammalian target of rapamycin [mTOR] inhibitors) or antiangiogenic agents are currently being investigated to improve the efficacy of antimelanoma therapies. This review discusses the implications of simultaneously targeting key regulators of melanoma cell proliferation/survival and immune responses to counteract resistance.

License for destruction: tumor-specific cytokine targeting

Stroma is an integral part of solid tumors and plays a key role in growth promotion and immune suppression. Most current therapies focus on destroying tumors and/or abnormal vasculature. However, evidence is emerging that anticancer efficacy improves with vessel normalization rather than destruction. Specific targeting of cytokines into tumors provides proof-of-concept that tumor stroma is dynamic and can be remodeled to increase drug access and alleviate immune suppression. Changing the inflammatory milieu 'opens' tumors for therapy and thus provides a license for destruction. This involves reprogramming of paracrine signaling networks between multiple stromal components to break the vicious cycle of angiogenesis and immune suppression. With active immunotherapy rapidly moving into the clinic, local cytokine delivery emerges as an attractive adjuvant.

Immunocytokines: a review of molecules in clinical development for cancer therapy

The concept of therapeutically enhancing the immune system’s responsiveness to tumors is long standing. Several cytokines have been investigated in clinical trials for their therapeutic activity in cancer patients. However, substantial side effects and unfavorable pharmacokinetic properties have been a major drawback hampering the administration of therapeutically relevant doses. The use of recombinant antibody–cytokine fusion proteins promises to significantly enhance the therapeutic index of cytokines by targeting them to the site of disease. This review aims to provide a concise and complete overview of the preclinical data and clinical results currently available for all immunocytokines having reached clinical development.

Combination therapy of immunocytokines with ipilimumab: a cure for melanoma?

Although biological therapy has shown promising clinical responses in many cancers including metastatic melanoma, only a subset of patients has shown marked regression of lesions. In most patients, systemic administration of biological therapies with cytokines is associated with severe toxicities. Schwager et al., in this issue of Journal of Investigative Dermatology, have examined the role of immunocytokines L19-IL2 and L19-TNF to minimize toxicities, and in combination with Ipilimumab they report complete regression of tumors using syngeneic mouse models. The results, if confirmed in clinical trials, will have major implications for the treatment of human cancers, including melanomas.