Targeted enhancement of the therapeutic window of L19-TNF by transient and selective inhibition of RIPK1-signaling cascade

Introduction

Cytokine-based products are gaining importance for cancer immunotherapy. L19-TNF is a clinical-stage antibody-cytokine fusion protein that selectively accumulates to tumors and displays potent anticancer activity in preclinical models. Here, we describe an innovative approach to transiently inhibit off-target toxicity of L19-TNF, while maintaining antitumor activity.

Methods

GSK’963, a potent small molecule inhibitor of RIPK1, was tested in tumor-bearing mice for its ability to reduce acute toxicity associated with TNF signaling. The biological effects of L19-TNF on tumor cells, lymphocytes and tumor vessels were investigated with the aim to enable the administration of TNF doses, which would otherwise be lethal.

Results

Transient inhibition of RIPK1 allowed to increase the maximal tolerated dose of L19-TNF. The protective effect of GSK’963 did not affect the selective localization of the immunocytokine to tumors as evidenced by quantitative biodistribution analysis and allowed to reach high local TNF concentrations around tumor blood vessels, causing diffused vascular shutdown and hemorrhagic necrosis within the neoplastic mass.

Conclusions

The selective inhibition of RIPK1 with small molecule inhibitors can be used as a pharmaceutical tool to transiently mask TNF activity and improve the therapeutic window of TNF-based biopharmaceuticals. Similar approaches may be applicable to other pro-inflammatory cytokines.

A Novel Fully-Human Potency-Matched Dual Cytokine-Antibody Fusion Protein Targets Carbonic Anhydrase IX in Renal Cell Carcinomas

Certain cytokines synergize in activating anti-cancer immunity at the site of disease and it may be desirable to generate biopharmaceutical agents, capable of simultaneous delivery of cytokine pairs to the tumor. In this article, we have described the cloning, expression and characterization of IL2-XE114-TNF^mut, a dual-cytokine biopharmaceutical featuring the sequential fusion of interleukin-2 (IL2) with the XE114 antibody in scFv format and a tumor necrosis factor mutant (TNF^mut). The fusion protein recognized the cognate antigen (carbonic anhydrase IX, a marker of hypoxia and of renal cell carcinoma) with high affinity and specificity. IL2-XE114-TNF^mut formed a stable non-covalent homotrimeric structure, displayed cytokine activity in in vitro tests and preferentially localized to solid tumors in vivo. The product exhibited a partial growth inhibition of murine CT26 tumors transfected for carbonic anhydrase IX. When administered to Cynomolgus monkey as intravenous injection, IL2-XE114-TNF^mut showed the expected plasma concentration of ~1,500 ng/ml at early time points, indicating the absence of any in vivo trapping events, and a half-life of ~2 h. IL2-XE114-TNF^mut may thus be considered as a promising biopharmaceutical for the treatment of metastatic clear-cell renal cell carcinoma, since these tumors are known to be sensitive to IL2 and to TNF.

Antibody-Mediated Delivery of VEGFC Ameliorates Experimental Chronic Colitis

Crohn's disease (CD) and ulcerative colitis (UC) are two distinct forms of inflammatory bowel disease (IBD) characterized by an expanded lymphatic network with impaired functionality both in mouse models and in human patients. In this study, we investigated whether targeted delivery of the pro-lymphangiogenic vascular endothelial growth factor C (VEGFC) to the site of inflammation may represent a new, clinically feasible strategy for treating IBD. To achieve targeting of inflamed tissue, we developed a fusion protein consisting of human VEGFC fused to the F8 antibody (F8-VEGFC), which specifically binds to the extradomain A (EDA) of fibronectin, a spliced isoform almost exclusively expressed in inflamed tissues. The therapeutic activity of intravenously administered F8-VEGFC, compared to a targeted construct lacking VEGFC (F8-SIP), was investigated in a mouse model of dextran sodium sulfate (DSS)-induced colitis. The presence of EDA fibronectin was detected in both human and mouse inflamed colon tissue. Biodistribution studies of radiolabeled F8-VEGFC revealed a specific accumulation of the antibody in the colon of DSS-administered mice, as compared to an untargeted VEGFC fusion protein (KSF-VEGFC) (binding the irrelevant hen egg lysozyme antigen). Systemic treatment with F8-VEGFC significantly reduced the clinical and histological signs of inflammation, expanded the lymphatic vascular network, reduced the density of immune cells, and also decreased the expression of inflammatory cytokines in the inflamed colon. Overall, these results reveal that administration of F8-VEGFC represents a novel and promising approach for the treatment of IBD.

P12.08 Immunocytokines are a novel immunotherapeutic approach against glioblastoma

BACKGROUND

Glioblastoma is the most common malignant primary brain tumor in adults with an urgent need for novel treatment options. The administration of pro-inflammatory cytokines could be a potent immunotherapeutic approach to shift the balance between tumor-associated immunosuppression and immune activation. However, the systemic administration of therapeutically active doses of pro-inflammatory cytokines is not feasible due to toxic side effects and there is a need for strategies that enable a targeted delivery of pro-inflammatory cytokines to the tumor site.

METHODS

We investigated different antibody-cytokine fusion products that enable a targeted delivery of interleukin (IL)-2, IL-12 or tumor necrosis factor (TNF)-α to the tumor site by binding to a tumor-specific epitope of fibronectin. We investigated the expression of this tumor-specific epitope ex vivo in tumor-bearing mouse brains and human glioblastoma samples. Subsequently, we assessed the anti-tumor activity of IL-2, IL-12 or TNF-α fused to an antibody targeting this tumor-specific epitope in orthotopic syngeneic mouse glioma models.

RESULTS

The tumor-specfic extra domain B of fibronectin is expressed in murine glioma models and human glioblastoma samples. A fluorochrome-labeled antibody targeting this tumor-specific epitope accumulated at the tumor site in the brain in vivo upon systemic administration. IL-2, IL-12, or TNF-α fused to this antibody conferred a survival benefit in orthotopic tumor-bearing mice and cured a fraction of tumor-bearing mice. Mechanistically, antibody-fused TNF-α induced tumor necrosis and increased the activation of tumor-infiltrating natural killer (NK) cells, whereas antibody-fused IL-12 mainly boosted an anti-tumor immune response mediated by NK cells and T cells.

CONCLUSION

We demonstrate the expression of a tumor-specific epitope of fibronectin in glioblastoma and exploit this for the targeted delivery of IL-2, IL-12 or TNF-α to the tumor site. Our preclinical assessments indicate potent anti-tumor activity in orthotopic, syngneic glioma mouse models and reveal the mode of action for the different immunocytokines. Based on these findings, we initiated a phase I/II clinical trial in patients with recurrent glioma to investigate the targeted delivery of TNF-α (ClinicalTrials.gov identifier NCT03779230).

A phase II study of the L19IL2 immunocytokine in combination with dacarbazine in advanced metastatic melanoma patients

Engineered cytokine products represent promising agents for the treatment of immunogenic tumors, such as malignant melanoma, in addition to immune checkpoint inhibitors. Here we describe the results of a controlled, randomized phase II clinical trial, aimed at assessing the therapeutic potential of L19IL2, a fully human fusion protein consisting of the L19 antibody specific to the alternatively spliced extra-domain B of fibronectin, fused to human interleukin-2 in advanced metastatic melanoma. In one arm, patients received dacarbazine (DTIC; 1000 mg/m² of body surface on day 1 of 21-day cycles) as single agent, while in two other arms L19IL2 (22.5 million international units of IL2 equivalents) was added, based on two different schedules of administration. In total, 69 patients with stage IV melanoma were enrolled (24 in the dacarbazine arm, 23 and 22 in the other combination arms, respectively) and 67 received treatment. Analyses of efficacy results show a statistically significant benefit in terms of overall response rate and median progression-free survival for patients receiving L19IL2 in combination with DTIC, compared to DTIC as single agent. In light of these results, further clinical investigations with L19IL2 (alone or in combination with other agents) are warranted.

The antibody-based delivery of interleukin-12 to solid tumors boosts NK and CD8+ T cell activity and synergizes with immune checkpoint inhibitors

We describe the cloning and characterization of a novel fusion protein (termed L19-mIL12), consisting of murine interleukin-12 in single-chain format, sequentially fused to the L19 antibody in tandem diabody format. The fusion protein bound avidly to the cognate antigen (the alternatively spliced EDB domain of fibronectin), retained the activity of the parental cytokine and was able to selectively localize to murine tumors in vivo, as shown by quantitative biodistribution analysis. L19-mIL12 exhibited a potent antitumor activity in immunocompetent mice bearing CT26 carcinomas and WEHI-164 sarcomas, which could be boosted by combination with checkpoint blockade, leading to durable cancer eradication. L19-mIL12 also inhibited tumor growth in mice with Lewis lung carcinoma (LLC), but in this case, cancer cures could not be obtained, both in monotherapy and in combination. A microscopic analysis and a depletion experiment of tumor-infiltrating leukocytes illustrated the contribution of NK cells and CD8⁺ T cells for the anticancer activity observed in both tumor models. Upon L19-mIL12 treatment, the density of regulatory T cells (Tregs) was strongly increased in LLC, but not in CT26 tumors. A FACS analysis also revealed that the majority of CD8⁺ T cells in CT26 tumors were specific to the retroviral AH1 antigen.

Intratumoral administration of IL2- and TNF-based fusion proteins cures cancer without establishing protective immunity

AIM

The combination of tumor-targeting IL2- and TNF-based antibody-cytokine fusions has exhibited encouraging results in mouse and men. Here, we studied their combination to assess efficacy and mechanism of action in four different immunocompetent mouse models of cancer.

METHODS

Mice receiving a single intratumoral injection of F8-IL2, F8-TNF or the combination were investigated for tumor-infiltrating leukocytes and rechallenged when cured.

RESULTS

In three models, a proportion of treated animals could be cured, most probably by infiltrating NK and CD8⁺ T cells. Most of the cured mice did not acquire protective immunity when rechallenged with the same tumor cell line.

CONCLUSION

Immunocompetent mouse tumor models may not be adequate enough to predict the search for more efficacious therapy regimens.

Development of a novel fully-human anti-CD123 antibody to target acute myeloid leukemia

Monoclonal antibodies are being considered as biopharmaceuticals for the in vivo targeting of acute myeloid leukemia. Here we describe the generation and characterization of a fully-human monoclonal antibody specific to CD123, a surface marker which is overexpressed in a variety of hematological disorders, including acute myeloid leukemia. The cloning and expression of the extracellular portion of CD123 as recombinant Fc fusion allowed the selection and affinity maturation of a human antibody, called H9, which specifically recognized the cognate antigen in biochemical assays and on leukemic cells. The H9 antibody and a previously-described anti-CD123 antibody (CSL362) were reformatted into full immunoglobulin human IgG1 formats, including a variant bearing S293D and I332E mutations to enhance antibody-dependent cell-mediated cytotoxicity (ADCC). The two antibodies recognized different epitopes on the surface of the N-terminal domain of CD123, as revealed by crystallography and SPOT analysis. Both H9 and CSL362 in full immunoglobulin format were able to selectively kill leukemic cells in in vitro ADCC assays, performed both with cell lines and with patient-derived AML blasts. Further, the two antibodies, when reformatted as bispecific BiTE™ reagents by fusion with the anti-CD3 scFv(OKT3) antibody fragment, induced selective killing of AML blasts by patient-derived, autologous T-cells in an in vitro setting, but BiTE(CSL362/OKT3) exhibited a 10-fold higher potency compared to BiTE(H9/OKT3). The availability of two classes of CD123-specific biopharmaceuticals, capable of redirecting the cytolytic activity of NK cells and T cells against AML blasts, may enable novel interventional strategies and combination opportunities for the treatment of AML.

Antibody-Based Delivery of Cytokine Payloads to Carbonic Anhydrase IX Leads to Cancer Cures in Immunocompetent Tumor-Bearing Mice

Antibody-cytokine fusion proteins can have the potential to increase the density and activity of subsets of leukocytes within the tumor mass. Here, we describe the design, production, and characterization of four novel antibody-cytokine fusion proteins directed against human carbonic anhydrase IX, a highly validated marker of hypoxia that is overexpressed in clear cell renal cell carcinoma and other malignancies. As immunomodulatory payloads we used TNF, IL2, IFNα2 (corresponding to products that are in clinical use), and IL12 (as this cytokine potently activates T cells and NK cells). Therapy experiments were performed in BALB/c mice, bearing CT26 tumors transfected with human carbonic anhydrase IX, in order to assess the performance of the fusion proteins in an immunocompetent setting. The biopharmaceuticals featuring TNF, IL2, or IL12 as payloads cured all mice in their therapy groups, whereas only a subset of mice was cured by the antibody-based delivery of IFNα2. Although the antibody fusion with TNF mediated a rapid hemorrhagic necrosis of the tumor mass, a slower regression of the neoplastic lesions (which continued after the last injection) was observed with the other fusion proteins, and treated mice acquired protective anticancer immunity. A high proportion of tumor-infiltrating CD8⁺ T cells was specific to the retroviral antigen AH1; however, the LGPGREYRAL peptide derived from human carbonic anhydrase IX was also present on tumor cells. The results described herein provide a rationale for the clinical use of fully human antibody-cytokine fusions specific to carbonic anhydrase IX.

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.

ALCAM Mediates DC Migration Through Afferent Lymphatics and Promotes Allospecific Immune Reactions

Activated leukocyte cell adhesion molecule (ALCAM, CD166) is a cell adhesion molecule of the immunoglobulin superfamily and has been implicated in diverse pathophysiological processes including T cell activation, leukocyte trafficking, and (lymph)angiogenesis. However, exploring the therapeutic potential of ALCAM blockade in immune-mediated inflammatory disorders has been difficult due to the lack of antibodies with blocking activity toward murine ALCAM. In this study, we identified and characterized a monoclonal antibody with high affinity and specificity for murine ALCAM. This antibody reduced in vitro T cell activation induced by antigen-presenting dendritic cells (DCs) as well as (trans)migration of murine DCs across lymphatic endothelial monolayers. Moreover, it reduced emigration of DCs from in vitro-cultured human skin biopsies. Similarly, antibody-based blockade of ALCAM reduced (lymph)angiogenic processes in vitro and decreased developmental lymphangiogenesis in vivo to levels observed in ALCAM-deficient mice. Since corneal allograft rejection is an important medical condition that also involves (lymph)angiogenesis, DC migration and T cell activation, we investigated the therapeutic potential of ALCAM blockade in murine corneal disease. Blocking ALCAM lead to DC retention in corneas and effectively prevented corneal allograft rejection. Considering that we also detected ALCAM expression in human corneal DCs and lymphatics, our findings identify ALCAM as a potential novel therapeutic target in human corneal allograft rejection.

Screening of copper and palladium-mediated reactions compatible with DNA-encoded chemical libraries

The construction of DNA-encoded chemical libraries (DECLs) crucially relies on the availability of chemical reactions, which are DNA-compatible and which exhibit high conversion rates for a large number of diverse substrates. In this work, we present our optimization and validation procedures for three copper and palladium-catalyzed reactions (Suzuki cross-coupling, Sonogashira cross-coupling and copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC)), which have been successfully used by our group for the construction of large encoded libraries.

A fully human anti-IL-7Rα antibody promotes antitumor activity against T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological cancer for which treatment options often result in incomplete therapeutic efficacy and long-term side-effects. Interleukin 7 (IL-7) and its receptor IL-7Rα promote T-ALL development and mutational activation of IL-7Rα associates with very high risk in relapsed disease. Using combinatorial phage-display libraries and antibody reformatting, we generated a fully human IgG1 monoclonal antibody (named B12) against both wild-type and mutant human IL-7Rα, predicted to form a stable complex with IL-7Rα at a different site from IL-7. B12 impairs IL-7/IL-7R-mediated signaling, sensitizes T-ALL cells to treatment with dexamethasone and can induce cell death per se. The antibody also promotes antibody-dependent natural killer-mediated leukemia cytotoxicity in vitro and delays T-cell leukemia development in vivo, reducing tumor burden and promoting mouse survival. B12 is rapidly internalized and traffics to the lysosome, rendering it an attractive vehicle for targeted intracellular delivery of cytotoxic cargo. Consequently, we engineered a B12–MMAE antibody–drug conjugate and provide proof-of-concept evidence that it has increased leukemia cell killing abilities as compared with the naked antibody. Our studies serve as a stepping stone for the development of novel targeted therapies in T-ALL and other diseases where IL-7Rα has a pathological role.

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.

A novel dual-cytokine-antibody fusion protein for the treatment of CD38-positive malignancies

A novel dual-cytokine-antibody fusion protein, consisting of an antibody directed against CD38 [a tumor-associated antigen mainly expressed on the surface of multiple myeloma (MM) cells], simultaneously fused to both tumor necrosis factor ligand superfamily member 10 (TRAIL) and interleukin-2 (IL2), was designed, expressed and purified to homogeneity. The novel fusion protein, termed IL2-αCD38-αCD38-scTRAIL, was able to selectively recognize its cognate antigen expressed on the surface of MM and lymphoma cell lines, as evidenced by flow cytometry analysis. Moreover, the targeted version of TRAIL was able to induce cancer cell death in vitro, both with MM cell lines and with fresh isolates from the bone marrow of MM patients. The experiments provide a rationale for possible future applications of IL2-αCD38-αCD38-scTRAIL for the treatment of patients with MM or other CD38-positive malignancies.

Erratum: In Vivo Antitumor Activity of a Novel Acetazolamide-Cryptophycin Conjugate for the Treatment of Renal Cell Carcinoma

[This corrects the article DOI: 10.1021/acsomega.8b02350.].

F8-IL10: A New Potential Antirheumatic Drug Evaluated by a PET-Guided Translational Approach

Antibody fragment F8-mediated interleukin 10 (IL10) delivery is a novel treatment for rheumatoid arthritis (RA). F8 binds to the extra-domain-A of fibronectin (ED-A). In this study, in vivo biodistribution and arthritis targeting of radiolabeled F8-IL10 were investigated in RA patients, followed by further animal studies. Therefore, three RA patients (DAS28 > 3.2) received 0.4 mg of 30–74 megabecquerel [¹²⁴I]I–F8–IL10 for PET-CT and blood sampling. In visually identified PET-positive joints, target-to-background was calculated. Healthy mice, rats, and arthritic rats were injected with iodinated F8-IL10 or KSF-IL10 control antibody. Various organs were excised, weighed, and counted for radioactivity. Tissue sections were stained for fibronectin ED-A. In RA patients, [¹²⁴I]I–F8–IL10 was cleared rapidly from the circulation with less than 1% present in blood after 5 min. PET-CT showed targeting in 38 joints (11–15 per patient) and high uptake in the liver and spleen. Mean target-to-background ratios of PET-positive joints were 2.5 ± 1.2, 1.5 times higher for clinically active than clinically silent joints. Biodistribution of radioiodinated F8-IL10 in healthy mice showed no effect of the radioiodination method. [¹²⁴I]I–F8–IL10 joint uptake was also demonstrated in arthritic rats, ∼14-fold higher than that of the control antibody [¹²⁴I]I-KSF-IL10 (p < 0.001). Interestingly, liver and spleen uptake were twice as high in arthritic than in healthy rats and were related to increased (∼7×) fibronectin ED-A expression in these tissues. In conclusion, [¹²⁴I]I–F8–IL10 uptake was observed in arthritic joints in RA patients holding promise for visualization of inflamed joints by PET-CT imaging and therapeutic targeting. Patient observations and, subsequently, arthritic animal studies pointed to awareness of increased [¹²⁴I]I–F8–IL10 uptake in the liver and spleen associated with moderate systemic inflammation. This translational study demonstrated the value of in vivo biodistribution and PET-CT-guided imaging in development of new and potential antirheumatic drugs’.

Targeted delivery of calreticulin to ED-A fibronectin leads to tumor-growth retardation

We report the design and characterization of novel fusion proteins, consisting of the F8 antibody and of murine calreticulin (Calr). The F8 antibody recognizes the alternatively-spliced ED-A domain of fibronectin, an extracellular matrix component found in most tumor types, while calreticulin has previously been described as an "eat-me" signal for dendritic cells and phagocytes. Four fusion proteins, differing in antibody formats and peptide linkers, were produced in mammalian cells, purified to homogeneity and tested in vitro and in vivo. A quantitative biodistribution in F9 tumor-bearing mice revealed that the homobivalent F8-F8-Calr format, featuring a tandem diabody structure, had the best tumor-homing properties and, for this reason, this protein was studied in therapy experiments in CT26 tumor-bearing mice. Intravenous administration of F8-F8-Calr led to a tumor growth retardation, which could be further improved by combination with anti-PD1 antibody treatment. Immunohistochemical analysis revealed an increased density of CD8⁺ T cells, CD11c⁺ dendritic cells and F4/80⁺ macrophages in tumor tissue. Even though F8-F8-Calr did not lead to cancer cures at the doses tested, the excellent tolerability profile and the ability to favor a leukocyte infiltration into the neoplastic mass suggests that the targeted delivery of calreticulin may be considered for combination therapy approaches.

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.

Antibody-mediated delivery of VEGF-C potently reduces chronic skin inflammation

VEGF-C is an important mediator of lymphangiogenesis and has been shown to alleviate chronic inflammation in a variety of disease models. In this study, we investigated whether targeted delivery of VEGF-C to sites of inflammation and site-specific activation of lymphatic vessels would represent a clinically feasible strategy for treating chronic skin inflammation. To this end, we generated a fusion protein consisting of human VEGF-C fused to the F8 antibody (F8-VEGF-C), which is specific for the alternatively spliced, angiogenesis-marking extradomain A (EDA) of fibronectin. In two mouse models of psoriasis-like skin inflammation, mediated by transgenic VEGF-A overexpression or repeated application of imiquimod, intravenous treatment with F8-VEGF-C but not with untargeted VEGF-C significantly reduced ear skin edema and was as effective as the clinically used TNF-α receptor-Fc fusion protein (TNFR-Fc). Treatment with F8-VEGF-C led to a marked expansion of lymphatic vessels in the inflamed skin and significantly improved lymphatic drainage function. At the same time, treatment with F8-VEGF-C significantly reduced leukocyte numbers, including CD4+ and γδ T cells. In sum, our results reveal that targeted delivery of VEGF-C and site-specific induction of lymphatic vessels represent a potentially new and promising approach for the treatment of chronic inflammatory diseases.

In Vivo Antitumor Activity of a Novel Acetazolamide-Cryptophycin Conjugate for the Treatment of Renal Cell Carcinomas

Traditional chemotherapeutics used in cancer therapy do not preferentially accumulate in tumor tissues. The conjugation to delivery vehicles like antibodies or small molecules has been proposed as a strategy to increase the tumor uptake and improve the therapeutic window of these drugs. Here, we report the synthesis and the biological evaluation of a novel small molecule-drug conjugate (SMDC) comprising a high-affinity bidentate acetazolamide derivative, targeting carbonic anhydrase IX (CAIX), and cryptophycin, a potent microtubule destabilizer. The biological activity of the novel SMDC was evaluated in vitro, measuring binding to the CAIX antigen by surface plasmon resonance and cytotoxicity against SKRC-52 cells. In vivo studies showed a delayed growth of tumors in nude mice bearing SKRC-52 renal cell carcinomas.

Antibody-based Delivery of TNF to the Tumor Neovasculature Potentiates the Therapeutic Activity of a Peptide Anticancer Vaccine

PURPOSE

There is a growing interest in the use of tumor antigens for therapeutic vaccination strategies. Unfortunately, in most cases, the use of peptide vaccines in patients does not mediate shrinkage of solid tumor masses.Experimental Design: Here, we studied the opportunity to boost peptide vaccination with F8-TNF, an antibody fusion protein that selectively delivers TNF to the tumor extracellular matrix. AH1, a model antigen to investigate CD8⁺ T-cell immunity in BALB/c mice, was used as vaccine.

RESULTS

Peptide antigens alone exhibited only a modest tumor growth inhibition. However, anticancer activity could be substantially increased by combination with F8-TNF. Analysis of T cells in tumors and in draining lymph nodes revealed a dramatic expansion of AH1-specific CD8⁺ T cells, which were strongly positive for PD-1, LAG-3, and TIM-3. The synergistic anticancer activity, observed in the combined use of peptide vaccination and F8-TNF, was largely due to the ability of the fusion protein to induce a rapid hemorrhagic necrosis in the tumor mass, thus leaving few residual tumor cells. While the cell surface phenotype of tumor-infiltrating CD8⁺ T cells did not substantially change upon treatment, the proportion of AH1-specific T cells was strongly increased in the combination therapy group, reaching more than 50% of the CD8⁺ T cells within the tumor mass.

CONCLUSIONS

Because both peptide vaccination strategies and tumor-homing TNF fusion proteins are currently being studied in clinical trials, our study provides a rationale for the combination of these 2 regimens for the treatment of patients with cancer.

A DNA-Encoded Library of Chemical Compounds Based on Common Scaffolding Structures Reveals the Impact of Ligand Geometry on Protein Recognition

A DNA-encoded chemical library (DECL) with 1.2 million compounds was synthesized by combinatorial reaction of seven central scaffolds with two sets of 343×492 building blocks. Library screening by affinity capture revealed that for some target proteins, the chemical nature of building blocks dominated the selection results, whereas for other proteins, the central scaffold also crucially contributed to ligand affinity. Molecules based on a 3,5-bis(aminomethyl)benzoic acid core structure were found to bind human serum albumin with a Kd value of 6 nm, while compounds with the same substituents on an equidistant but flexible l-lysine scaffold showed 140-fold lower affinity. A 18 nm tankyrase-1 binder featured l-lysine as linking moiety, while molecules based on d-Lysine or (2S,4S)-amino-l-proline showed no detectable binding to the target. This work suggests that central scaffolds which predispose the orientation of chemical building blocks toward the protein target may enhance the screening productivity of encoded libraries.

Potentiation of PD-L1 blockade with a potency-matched dual cytokine-antibody fusion protein leads to cancer eradication in BALB/c-derived tumors but not in other mouse strains

We have recently described a novel therapeutic antibody product (IL2-F8-TNF^mut), featuring the simultaneous fusion of murine IL2 and of a TNF mutant with scFv(F8), an antibody specific to the alternatively-spliced extra domain A of fibronectin (EDA). Here, we report on the in vivo characterization of the anti-cancer activity of IL2-F8-TNF^mut in four immunocompetent murine models of cancer, CT26, WEHI-164, F9 teratocarcinoma and Lewis lung carcinoma (LLC), using the product alone or in combination with a monoclonal antibody specific to murine PD-L1. All four models exhibited a strong expression of EDA-fibronectin, which was confined to vascular structures for F9 tumors, while the other three malignancies exhibited a more stromal pattern of staining. A complete and long-lasting tumor eradication of CT26 and WEHI-164 tumors was observed in BALB/c mice when IL2-F8-TNF^mut was used in combination with PD-L1 blockade. The combination treatment led to improved tumor growth inhibition in 129/SvEv mice bearing murine teratocarcinoma or in C57BL/6 mice bearing murine LLC, but those cancer cures were difficult to achieve in those models. A microscopic analysis of tumor sections, obtained 24 h after pharmacological treatment, revealed that the PD-L1 antibody had homogenously reached tumor cells in vivo and that the combination of PD-L1 blockade with IL2-F8-TNF^mut stimulated an influx of NK cells and of T cells into the neoplastic mass. These data indicate that potency-matched dual-cytokine fusion proteins may be ideally suited to potentiate the therapeutic activity of immune check-point inhibitors.

Abstract 2785: Potency-matched dual cytokine antibody fusion proteins in combination with PD-L1 blockade

Among the different pharmacological approaches for cancer treatment, antibody-cytokine fusion proteins (also called “immunocytokines”) represent an emerging class of biopharmaceutical products, capable of boosting the immune system to attack tumor cells. These products promote the selective accumulation of pro-inflammatory molecules at the site of disease, mediated by the antibody fragment. These fusion proteins have been designed to reduce the systemic toxicity of traditional cytokines, currently approved for certain malignancies.

Immunocytokine products based on interleukin-2 (IL2), interleukin-12 (IL12) or tumor necrosis factor (TNF) have been extensively studied in mouse model of cancer and in patients.

When used as single agents, immunocytokines are often not able to cure mice and patients. However it as been shown by our group that the combination of IL2- and TNF- based products was capable to completely eradicate tumors in mouse models and to induce complete responses in patients.

The development of combination products at the industrial level leads to a duplication of activities and costs. On the other hand, the opportunity to develop products with two payloads fused into a single molecular entity may facilitate development. This approach is limited by the fact that different cytokines often show different maximal tolerated doses (MTDs), and their relative potency need to be tuned. For example, TNF is administered at a dose, which is ten times lower compered to the one of IL2.

We have recently described a novel class of immunocytokine products, termed “potency-matched dual cytokine antibody fusion proteins” consisting of a tumor-targeting antibody (for example F8, specific to the alternatively spliced EDA domain of fibronectin), simultaneously fused to both IL2 and TNF. To match biological activity of the two payloads a single-point mutation was inserted in the TNF sequence and the resulting product, named IL2-F8-TNFmut was able to selectively localize to lesions with an excellent tumor-to-organ ratios and it was found to completely eradicate soft-tissue sarcomas in immunocompetent mice, which did not respond to standard chemotherapy. We now report that complete responses were observed in a variety of mouse models of cancer and that the therapeutic efficacy of IL2-F8-TNFmut was further improved when used in combination with an anti-PD-L1 antibody.

Potency-matched dual cytokine antibody fusion proteins may find clinical applications for various types of malignancies, used either as single agents or in combination with immune-checkpoint inhibitors.

Citation Format: Roberto De Luca, Dario Neri. Potency-matched dual cytokine antibody fusion proteins in combination with PD-L1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2785.

Abstract 2768: Potentiating the action of antibody-dependent cell-mediated cytotoxicity with immunocytokines

Intact antibodies in the IgG format typically display only moderate in vivo activity against solid tumor masses, when their mechanism of action relies on antibody-dependent cellular cytotoxicity (ADCC). The therapeutic activity is mainly limited by the lack of immune effector cells (and most notably NK cells) in the neoplastic mass.

Our group had previously reported that the therapeutic activity of Rituximab and other intact immunoglobulins could be strongly potentiated by the antibody-based targeted delivery of interleukin-2 (IL2) to the tumor environment. The combination regimen induced complete remissions of established localized lymphomas and provided long-lasting protection from disseminated lymphoma, in mouse models that featured functional NK cells.

In this study, we examined the ADCC activity of TA99, a monoclonal antibody which specifically recognizes gp75, a conserved tumor-associated antigen over-expressed in both murine and human melanoma cells. In a preventive setting TA99 in murine IgG2a format completely inhibited the formation of lung metastases in mice, which had been injected intravenously with B16F10 melanoma cells. However, when the B16F10 melanoma tumor was grown subcutaneously in immunocompetent mice, the ADCC activity was not potent enough to eradicate the pre-established tumors and only a modest tumor growth inhibition was observed. A microscopic tissue distribution analysis revealed that TA99-IgG2a had selectively accumulated in the tumor mass compared to normal organs and that NK cells within the neoplastic lesions were scarce.

In order to increase NK cell density at the tumor site and potentiate ADCC activity, we developed fusion proteins of the TA99 antibody with murine TNFα, IL2 and IL12. The antibody-cytokine fusion proteins were used alone and in combination with TA99-IgG2a. Combination treatment led to a marked increase of anti-cancer activity against established subcutaneous tumors. Our findings indicate that the targeted delivery of certain pro-inflammatory cytokines to the tumor site potentiates the anti-cancer properties of intact antibodies, enhancing their ability to induce ADCC.

Citation Format: Patrizia Murer, Jonathan D. Kiefer, Louis Plüss, Dario Neri. Potentiating the action of antibody-dependent cell-mediated cytotoxicity with immunocytokines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2768.

Abstract 758: Head-to-head comparison of ADC and SMDC products, alone and in combination with antibody-IL2 fusion proteins

In an attempt to improve the therapeutic index of cancer chemotherapy, monoclonal antibodies and small organic ligands have been proposed as delivery vehicles, allowing the construction of antibody-drug conjugates (ADCs) and of small molecule-drug conjugates (SMDCs). Four ADC products have gained marketing authorization for cancer therapy, while SMDCs are still being investigated in clinical trials. SMDCs could in principle offer certain advantages compared to ADCs, such as a more rapid and uniform diffusion into the tumor mass, lower cost-of-goods and lack of immunogenicity, but a direct head-to-head comparison has not yet been reported.

Here we describe a novel small molecule-drug conjugate, based on a high-affinity ligand specific to carbonic anhydrase IX. The product features a peptide linker, suitable for cleavage in the tumor extracellular environment, and monomethyl auristatin E as cytotoxic payload. We compared the therapeutic efficacy of the novel SMDC and of an anti-CAIX ADC, which were injected at equimolar doses in nude mice bearing SKRC-52 renal cell carcinoma xenografts. Both products showed a potent anti-cancer activity, although no complete tumor eradication was observed. Instead, when the SMDC was administered together with L19-IL2 (a clinical-stage fusion protein capable of delivering interleukin-2 to the tumor neo-vasculature), all treated mice in the combination group could be rendered tumor-free, in a process which 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. These findings may be of clinical significance, since carbonic anhydrase IX is over-expressed in the majority of clear-cell renal cell carcinomas and in approximately 30% of colorectal cancers. The targeted delivery of interleukin-2 helps potentiate the action of targeted cytotoxics leading to cancer eradication in models that cannot be cured by conventional chemotherapy.

Citation Format: Samuele Cazzamalli, Alberto Dal Corso, Fontaine Widmayer, Dario Neri. Head-to-head comparison of ADC and SMDC products, alone and in combination with antibody-IL2 fusion proteins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 758.

Abstract 5563: Kinetically-controlled release of blocking molecules for the targeted enhancement of therapeutic activity in antibody-cytokine fusion proteins

Cytokines are able to mediate a potent anticancer activity but have significant side effects that prevent dose escalation to therapeutically-active regimens. Targeting the cytokines to the site of disease helps to improve their therapeutic index while decreasing associated toxicities. However, peak concentrations in blood are still associated with side-effects. We have developed a novel technology (termed “CORK Technology”), which consists in masking the undesired activity of a cytokine in circulation. The “cork” can be either an antibody fragment or a small molecule, which specifically binds to the cytokine thus preventing the interaction with its receptor. Once the complex accumulates in the tumor, the cork dissociate from the cytokine allowing it to exert its function. Capitalizing on the fact that the kinetic dissociation constant koff of the complex is identical in different species, this technology can be easily translated from mouse to man with comparable results. In this poster we describe the experimental implementation of CORK Technology to improve the therapeutic index of the clinical stage L19-IL2 (L19 is an antibody fragment specific to the alternatively-spliced EDB domain of fibronectin, a marker of tumor angiogenesis). Two classes of IL2 inhibitors were discovered and characterized: (i) a fully human scFv fragment, and (ii) a small organic ligand, featuring a modified methylindole moiety. Both types of agents reduced IL2 activity in vitro, were able to dissociate from the cognate cytokine in a kinetically-tuned process and allowed the administration of the L19-IL2 fusion protein at higher doses, both in normal and in tumor-bearing mice. The technology is applicable to other cytokine payloads and facilitates the development of targeted cytokine products with “activity on demand” (i.e., with increased activity at the tumor site, promoting an activation and proliferation of tumor-resident lymphocytes). Albeit still in its infancy, this elegant approach provides promising results and a strong rationale to further investigate this therapeutic power of the CORK Technology.

Citation Format: Tiziano Ongaro, Martina Bigatti, Filippo Sladojevich, Etienne Donckele, Alessandra Micaela Villa, Dario Neri. Kinetically-controlled release of blocking molecules for the targeted enhancement of therapeutic activity in antibody-cytokine fusion proteins [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5563.

Abstract 5553: A novel immunocytokine for the treatment of cancer

Interleukin-12 (IL12) is an immunomodulatory cytokine, which offers unique opportunities for cancer therapy due to its stimulatory function on cell-mediated immunity and its anti-angiogenic activity. IL12 was shown to polarize CD4+ T cells into a TH1 type and to be a key activator of NK cells and CD8+ T cells. It also induces the production of interferon-gamma by T cells and NK cells and subsequently of the anti-angiogenic chemokines CXCL10/IP-10, and CXCL9/Mig. However the potent anti-tumor IL12 activity, which has been reported in mice, has not yet been successfully translated into clinical development, mainly because of early reports of severe toxicity and low response rates in human. Following our pioneering work which started in 2002 with the first description of an IL12 based antibody-cytokine fusion protein (i.e. Immunocytokine), we have extensively explored and perfected alternative molecular formats, with the aim to further improve biodistribution properties and therapeutic activity of IL12-based immunocytokines. Here we describe the development and evaluation of new targeted variants of both murine and human IL-12 with enhanced therapeutic efficacy and improved safety profile. To this end we combined the immunomodulatory properties of the IL12 payload with the tumor-homing activity of the L19 antibody. L19 is a clinical grade fully human antibody, which recognizes with identical affinity in both mouse and human, the alternatively spliced EDB domain of fibronectin. EDB represent an optimal target for anti-cancer pharmacodelivery, due to its pan-tumoral over-expression nature combined with very low expression levels in normal tissues. This has also been confirmed by extensive Nuclear Medicine work in which radiolabeled L19 has been administered to more than 150 patients, making L19 one of the best validated tumor-targeting agent. Our novel immunocytokine, termed IL12-L19-L19, relies on the L19 antibody in tandem diabody format, with a monomeric IL12 moiety expressed as single-chain polypeptide at the N-terminal extremity. Recombinant IL12-L19-L19 proteins based either on human or murine IL12, were efficiently expressed in CHO cells and purified to high quality. The tumor-targeting properties of both variants were validated in tumor-bearing mice, using radioiodinated protein preparations. In preclinical therapy studies IL12-L19-L19 showed potent anti-cancer activity when used either as single agent or in combination with other anticancer agents. PK studies in Cynomolgus Monkey using the fully human IL12-L19-IL19 product, revealed a favorable profile, which is compatible with other clinical-stage immunocytokines based on antibody-fragments. These results strongly support the further development of the fully human IL12-L19-L19 product for future clinical investigations.

Citation Format: Mattia Matasci, Emanuele Puca, Tiziano Ongaro, Sarah Wulhfard, Alessandra Villa, Dario Neri. A novel immunocytokine for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5553.

Abstract 3811: Targeted Interleukin 2 and synergy with immune check-point inhibitors

Systemic high-dose Interleukin 2 (IL2) is able to elicit complete responses in patients suffering from metastatic melanoma. However, the majority of patients cannot receive the whole treatment dose due to severe toxicities. Other approved drugs for the treatment of metastatic melanoma include chemotherapeutics (e.g. Dacarbazine), a protein kinase B-raf inhibitor (Vemurafenib) and an immune check-point inhibitor (Ipilimumab, an anti CTLA-4 antibody). These drugs provide a clear benefit to patients, but cancer cures are still rare.

Targeting IL2 to the site of disease represents a promising strategy to circumvent the toxicity and maximize the efficacy of this immunomodulatory payload. Various formats of targeted IL2 fusion proteins are currently in clinical development. Furthermore, recent successful approaches in the field of immunotherapy focus on the inhibition of check-point pathways, aiming to release the immunosuppressive brakes of the immune system. To explore the possibility of improving therapeutic efficacy of the single agents, a targeted version of IL2 (namely F8-IL2, where the F8 antibody recognizes the alternatively-spliced extra-domain A of fibronectin) was investigated in combination with an anti PD-1, anti PD-L1, or anti CTLA-4 antibody in an immunocompetent mouse model of CT26 colon carcinoma. In a first study, the combination of F8-IL2 and CTLA-4 blockade led to significant tumor growth retardation (curing 3/ 5 mice). Increasing the dose of F8-IL2 from 30 to 45 µg led to a 100 % cure rate with no signs of toxicity (body weight loss &lt;5 %). Moreover, all cured mice acquired protective long-term immunity, which prevented tumor growth upon subsequent rechallenge with CT26 colon carcinoma cells. Furthermore, high dose F8-IL2 combined with the anti PD-1 antibody showed better therapeutic results than the respective monotherapies. In contrast, combination of F8-IL2 with the anti PD-L1 antibody did not improve the therapeutic outcome.

Taken together, these data provide a strong rationale for the clinical use of targeted IL2 in combination with Ipilimumab.

Citation Format: Cornelia Deborah Hutmacher-Berndt, Dario Neri. Targeted Interleukin 2 and synergy with immune check-point inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3811.

DNA-Encoded Chemical Libraries: A Selection System Based on Endowing Organic Compounds with Amplifiable Information

The discovery of organic ligands that bind specifically to proteins is a central problem in chemistry, biology, and the biomedical sciences. The encoding of individual organic molecules with distinctive DNA tags, serving as amplifiable identification bar codes, allows the construction and screening of combinatorial libraries of unprecedented size, thus facilitating the discovery of ligands to many different protein targets. Fundamentally, one links powers of genetics and chemical synthesis. After the initial description of DNA-encoded chemical libraries in 1992, several experimental embodiments of the technology have been reduced to practice. This review provides a historical account of important milestones in the development of DNA-encoded chemical libraries, a survey of relevant ongoing research activities, and a glimpse into the future.

Targeting the extradomain A of fibronectin allows identification of vascular resistance to antiangiogenic therapy in experimental glioma

Introduction

Clinical application of antiangiogenic therapy lacks direct visualization of therapy efficacy and vascular resistance. We aimed to establish molecular imaging during treatment with sunitinib using the fibronectin extradomain A specific small immunoprotein(SIP)-F8 in glioma.

Methods

Biodistribution analysis of F8-SIP-Alexa-555 was performed in SF126-glioma bearing or control mice (n = 23 and 7, respectively). Intravital microscopy(IVM) was performed on a microvascular level after 7 days (n = 5 per group) and subsequently after 6 days of sunitinib treatment (n = 4) or without (n = 2).

Additionally, near infrared fluorescence(NIRF) imaging was established with F8-SIP-Alexa-750 allowing non-invasive imaging with and without antiangiogenic treatment in orthotopic tumors (n = 38 divided in 4 groups). MRI was used to determine tumor size and served as a reference for NIRF imaging.

Results

F8-SIP demonstrated a time and hemodynamic dependent tumor specific accumulation. A significantly higher vascular accumulation occurred with antiangiogenic treatment compared to untreated tumors enabling visualization of resistant tumor vessels by F8-SIP-mediated NIRF imaging. In orthotopic tumors, sunitinib reduced F8-SIP-Alexa-750 enrichment volume but not fluorescence intensity indicative of F8-SIP accumulation in fewer vessels.

Conclusion

F8-SIP is highly tumor specific with time and hemodynamic dependent biodistribution. The higher vascular accumulation to remaining vessels enables molecular imaging and targeting of therapy resistant tumor vessels.

DNA-encoded chemical libraries - achievements and remaining challenges

DNA-encoded chemical libraries (DECLs) are collections of compounds, individually coupled to DNA tags serving as amplifiable identification barcodes. Since individual compounds can be identified by the associated DNA tag, they can be stored as a mixture, allowing the synthesis and screening of combinatorial libraries of unprecedented size, facilitated by the implementation of split-and-pool synthetic procedures or other experimental methodologies. In this review, we briefly present relevant concepts and technologies, which are required for the implementation and interpretation of screening procedures with DNA-encoded chemical libraries. Moreover, we illustrate some success stories, detailing how novel ligands were discovered from encoded libraries. Finally, we critically review what can realistically be achieved with the technology at the present time, highlighting challenges and opportunities for the future.

Covalent linkage of the DNA repair template to the CRISPR-Cas9 nuclease enhances homology-directed repair

The CRISPR-Cas9 targeted nuclease technology allows the insertion of genetic modifications with single base-pair precision. The preference of mammalian cells to repair Cas9-induced DNA double-strand breaks via error-prone end-joining pathways rather than via homology-directed repair mechanisms, however, leads to relatively low rates of precise editing from donor DNA. Here we show that spatial and temporal co-localization of the donor template and Cas9 via covalent linkage increases the correction rates up to 24-fold, and demonstrate that the effect is mainly caused by an increase of donor template concentration in the nucleus. Enhanced correction rates were observed in multiple cell types and on different genomic loci, suggesting that covalently linking the donor template to the Cas9 complex provides advantages for clinical applications where high-fidelity repair is desired.

Antibody-based targeted delivery of interleukin-4 synergizes with dexamethasone for the reduction of inflammation in arthritis

Objectives

We have previously reported that F8-IL4, a fusion protein consisting of the F8 antibody specific to the alternatively-spliced extra domain A of fibronectin and of murine IL-4, cures mice with established arthritis, when used in combination with dexamethasone (DXM). The goal of this study was to assess whether other therapeutic agents, besides DXM, could induce cures in combination with F8-IL4 and to elucidate which leucocytes are most affected by the pharmacological treatment.

Methods

We performed therapy experiments in mice with CIA, using intravenous administrations of F8-IL4 in combination with DXM, MTX, murine cytotoxic T-lymphocyte-associated protein 4 fused to the fragment crystallizable portion of murine IgG2a, as well as mAbs to murine IL17A or the p40 subunit of murine IL12/IL23. Histology and immunohistochemistry for the identification of the various leucocytes were performed on the paws of mice euthanized at different therapy time points.

Results

Only the use of F8-IL4 in combination with DXM induced complete remissions, while all other combinations did not lead to cures. The light microscopical evaluation of paws with arthritis revealed a predominant infiltration of neutrophils, which substantially decreased 24 h after treatment with F8-IL4 and DXM.

Conclusion

The combination of F8-IL4 with DXM promotes a rapid anti-arthritic action by potently inhibiting neutrophil activity. A fully human analogue of F8-IL4 may find clinical utility for the treatment of neutrophil-driven chronic inflammatory conditions.

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.