Candidate Genes Associated with Tumor Regression Mediated by Intratumoral Il-12 Electroporation Gene Therapy

XTX301, a Tumor-Activated Interleukin-12 Has the Potential to Widen the Therapeutic Index of IL12 Treatment for Solid Tumors as Evidenced by Preclinical Studies

IL12 is a proinflammatory cytokine, that has shown promising antitumor activity in humans by promoting the recruitment and activation of immune cells in tumors. However, the systemic administration of IL12 has been accompanied by considerable toxicity, prompting interest in researching alternatives to drive preferential IL12 bioactivity in the tumor. Here, we have generated XTX301, a tumor-activated IL12 linked to the human Fc protein via a protease cleavable linker that is pharmacologically inactivated by an IL12 receptor subunit beta 2 masking domain. In vitro characterization demonstrates multiple matrix metalloproteases, as well as human primary tumors cultured as cell suspensions, can effectively activate XTX301. Intravenous administration of a mouse surrogate mXTX301 demonstrated significant tumor growth inhibition (TGI) in inflamed and non-inflamed mouse models without causing systemic toxicities. The superiority of mXTX301 in mediating TGI compared with non-activatable control molecules and the greater percentage of active mXTX301 in tumors versus other organs further confirms activation by the tumor microenvironment-associated proteases in vivo. Pharmacodynamic characterization shows tumor selective increases in inflammation and upregulation of immune-related genes involved in IFNγ cell signaling, antigen processing, presentation, and adaptive immune response. XTX301 was tolerated following four repeat doses up to 2.0 mg/kg in a nonhuman primate study; XTX301 exposures were substantially higher than those at the minimally efficacious dose in mice. Thus, XTX301 has the potential to achieve potent antitumor activity while widening the therapeutic index of IL12 treatment and is currently being evaluated in a phase I clinical trial.

Safety and Efficacy of IL-12 Plasmid DNA Transfection into Pig Skin: Supportive Data for Human Clinical Trials on Gene Therapy and Vaccination

Gene electrotransfer (GET) of plasmids encoding interleukin 12 (IL-12) has already been used for the treatment of various types of tumors in human oncology and as an adjuvant in DNA vaccines. In recent years, we have developed a plasmid encoding human IL-12 (phIL12) that is currently in a phase I clinical study. The aim was to confirm the results of a non-clinical study in mice on pharmacokinetic characteristics and safety in a porcine model that better resembled human skin. The GET of phIL12 in the skin was performed on nine pigs using different concentrations of plasmid phIL12 and invasive (needle) or noninvasive (plate) types of electrodes. The results of our study demonstrate that the GET of phIL-12 with needle electrodes induced the highest expression of IL-12 at the protein level on day 7 after the procedure. The plasmid was distributed to all tested organs; however, its amount decreased over time and was at a minimum 28 days after GET. Based on plasmid copy number and expression results, together with blood analysis, we showed that IL-12 GET is safe in a porcine animal model. Furthermore, we demonstrated that pigs are a valuable model for human gene therapy safety studies.

Gene Immunotherapy of Colon Carcinoma with IL-2 and IL-12 Using Gene Electrotransfer

Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.

Gene electrotransfer of IL-2 and IL-12 plasmids effectively eradicated murine B16.F10 melanoma

Gene therapy has become an important approach for treating cancer, and electroporation represents a technology for introducing therapeutic genes into a cell. An example of cancer gene therapy relying on gene electrotransfer is the use of immunomodulatory cytokines, such as interleukin 2 (IL-2) and 12 (IL-12), which directly stimulate immune cells at the tumour site. The aim of our study was to determine the effects of gene electrotransfer with two plasmids encoding IL-2 and IL-12 in vitro and in vivo. Two different pulse protocols, known as EP1 (600 V/cm, 5 ms, 1 Hz, 8 pulses) and EP2 (1300 V/cm, 100 µs, 1 Hz, 8 pulses), were assessed in vitro for application in subsequent in vivo experiments. In the in vivo experiment, gene electrotransfer of pIL-2 and pIL-12 using the EP1 protocol was performed in B16.F10 murine melanoma. Combined treatment of tumours using pIL2 and pIL12 induced significant tumour growth delay and 71% complete tumour regression. Furthermore, in tumours coexpressing IL-2 and IL-12, increased accumulation of dendritic cells and M1 macrophages was obtained along with the activation of proinflammatory signals, resulting in CD4 + and CD8 + T-lymphocyte recruitment and immune memory development in the mice. In conclusion, we demonstrated high antitumour efficacy of combined IL-2 and IL-12 gene electrotransfer protocols in low-immunogenicity murine B16.F10 melanoma.

"Do We Know Jack" About JAK? A Closer Look at JAK/STAT Signaling Pathway

Janus tyrosine kinase (JAK) family of proteins have been identified as crucial proteins in signal transduction initiated by a wide range of membrane receptors. Among the proteins in this family JAK2 has been associated with important downstream proteins, including signal transducers and activators of transcription (STATs), which in turn regulate the expression of a variety of proteins involved in induction or prevention of apoptosis. Therefore, the JAK/STAT signaling axis plays a major role in the proliferation and survival of different cancer cells, and may even be involved in resistance mechanisms against molecularly targeted drugs. Despite extensive research focused on the protein structure and mechanisms of activation of JAKs, and signal transduction through these proteins, their importance in cancer initiation and progression seem to be underestimated. This manuscript is an attempt to highlight the role of JAK proteins in cancer biology, the most recent developments in targeting JAKs, and the central role they play in intracellular cross-talks with other signaling cascades.

Myeloid-restricted ablation of Shp2 restrains melanoma growth by amplifying the reciprocal promotion of CXCL9 and IFN-γ production in tumor microenvironment

The Src homology 2 domain-containing protein tyrosine phosphatase 2 (Shp2) is generally considered to be an oncogene owing to its ability in enhancing the malignancy of multiple types of tumor cells; however, its role in modulating tumor immunity remains largely elusive. Here, we reported that myeloid-restricted ablation of Shp2 suppressed melanoma growth. Mechanistically, loss of Shp2 potentiates macrophage production of CXCL9 in response to IFN-γ and tumor cell-derived cytokines, thereby facilitating the tumor infiltration of IFN-γ-producing T cells that could in turn support CXCL9 production within tumor microenvironment. Collectively, our findings highlight a causative role of myeloid Shp2 in dampening T cell-mediated antitumor immunity by restraining the macrophage/CXCL9-T cell/IFN-γ feedback loop. Thus, targeting macrophage Shp2 may help to create a Th1-dominant tumor immune microenvironment.

CXCL9: evidence and contradictions for its role in tumor progression

Chemokines are a group of low molecular weight peptides. Their major function is the recruitment of leukocytes to inflammation sites, but they also play a key role in tumor growth, angiogenesis, and metastasis. In the last few years, accumulated experimental evidence supports that monokine induced by interferon (IFN)‐gamma (CXCL9), a member of CXC chemokine family and known to attract CXCR3‐ (CXCR3‐A and CXCR3‐B) T lymphocytes, is involved in the pathogenesis of a variety of physiologic diseases during their initiation and their maintenance. This review for the first time presents the most comprehensive summary for the role of CXCL9 in different types of tumors, and demonstrates its contradictory role of CXCL9 in tumor progression. Altogether, this is a useful resource for researchers investigating therapeutic opportunities for cancer.

TRANSDERMAL DRUG DELIVERY AND METHODS TO ENHANCE IT

The paper presents the common methods employed in recent years for enhancing transdermal delivery of drug substances when applying transdermal therapeutic delivery systems. The chemical, physical and mechanical methods to enhance the transport of macromolecular compounds through the skin are considered in details. 

Gene therapy with IL-12 induced enhanced anti-tumor activity in fibrosarcoma mouse model

Context Immunotherapy is among the most promising modalities for treatment of cancer. Recently, interleukin 12 (IL-12) has been used as an immunotherapeutic agent in cancer gene therapy. IL-12 can activate dendritic cells (DCs) and boost anti-tumor immune responses. Objective In the current study, we have investigated if IL-12 gene therapy can lead to the regression of tumor mass in a mouse model of fibrosarcoma. Material and methods To investigate the therapeutic efficacy of IL-12, WEHI-164 tumor cells were transfected with murine-IL12 plasmids using Lipofectamine. Enzyme linked immunosorbent assay (ELISA) was used to confirm IL-12 expression in transfected cells. The fibrosarcoma mouse model was established by subcutaneous injection of transfected cells to Balb/C mice. Mice were sacrificed and the tumors were extracted. Tumor sizes were measured by caliper. The expression of IL-12 and IFN-γ was studied with real-time PCR and western blotting. The expression of Ki-67(a tumor proliferation marker) in tumor mass was studied by immunohistochemistry staining. Results and discussion The group treated with IL-12 showed a significant decrease in tumor mass volume (P: 0.000). The results of real-time PCR and western blotting showed that IL-12 and IFN-γ expression increased in the group treated with IL-12 (relative expression of IL-12: 1.9 and relative expression of IFN-γ: 1.766). Immunohistochemistry staining showed that Ki-67 expression was reduced in the group treated with IL-12. Conclusion IL-12 gene therapy successfully led to regress of tumor mass in the fibrosarcoma mouse model. This may serve as a candidate therapeutic approach for treatment of cancer.

An interferon signature identified by RNA-sequencing of mammary tissues varies across the estrous cycle and is predictive of metastasis-free survival

The concept that a breast cancer patient's menstrual stage at the time of tumor surgery influences risk of metastases remains controversial. The scarcity of comprehensive molecular studies of menstrual stage-dependent fluctuations in the breast provides little insight in this observation. To gain a deeper understanding of the biological changes in mammary tissue and blood during the menstrual cycle and to determine the influence of environmental exposures, such as low-dose ionizing radiation (LDIR), we used the mouse to characterize estrous-cycle variations in mammary gene transcripts by RNA-sequencing, peripheral white blood cell (WBC) counts and plasma cytokine levels. We identified an estrous-variable and hormone-dependent gene cluster enriched for Type-1 interferon genes. Cox regression identified a 117-gene signature of interferon-associated genes, which correlated with lower frequencies of metastasis in breast cancer patients. LDIR (10cGy) exposure had no detectable effect on mammary transcripts. However, peripheral WBC counts varied across the estrous cycle and LDIR exposure reduced lymphocyte counts and cytokine levels in tumor-susceptible mice. Our finding of variations in mammary Type-1 interferon and immune functions across the estrous cycle provides a mechanism by which timing of breast tumor surgery during the menstrual cycle may have clinical relevance to a patient's risk for distant metastases.

Interleukin 12: still a promising candidate for tumor immunotherapy?

Interleukin 12 (IL-12) seemed to represent the ideal candidate for tumor immunotherapy, due to its ability to activate both innate (NK cells) and adaptive (cytotoxic T lymphocytes) immunities. However, despite encouraging results in animal models, very modest antitumor effects of IL-12 in early clinical trials, often accompanied by unacceptable levels of adverse events, markedly dampened hopes of the successful use of this cytokine in cancer patients. Recently, several clinical studies have been initiated in which IL-12 is applied as an adjuvant in cancer vaccines, in gene therapy including locoregional injections of IL-12 plasmid and in the form of tumor-targeting immunocytokines (IL-12 fused to monoclonal antibodies). The near future will show whether this renewed interest in the use of IL-12 in oncology will result in meaningful therapeutic effects in a select group of cancer patients.

IL-12 and IL-27 sequential gene therapy via intramuscular electroporation delivery for eliminating distal aggressive tumors

Eradication of residual malignancies and metastatic tumors via a systemic approach is the key for successfully treating cancer and increasing cancer patient survival. Systemic administration of IL-12 protein in an acute large dose is effective but toxic. Systemic administration of IL-12 gene by persistently expressing a low level of IL-12 protein may reduce the systemic toxicity but only eradicates IL-12-sensitive tumors. In this study, we discovered that sequential administration of IL-12- and IL-27-encoding DNA, referred to as sequential IL-12-->IL-27 (IL-12 administration followed by IL-27 administration 10 d after) gene therapy, not only eradicated IL-12-sensitive CT26 tumors from 100% of mice but also eradicated the highly malignant 4T1 tumors from 33% of treated mice in multiple independent experiments. This IL-12-->IL-27 sequential gene therapy is not only superior to IL-12-encoding plasmid DNA given a total of two times at a 10-d interval sequential gene therapy for eliminating tumors but also for inducing CTL activity, increasing T cell infiltration into tumors, and yielding a large number of tumor-specific IFN-gamma-positive CD8 T cells. Notably, depletion of either T or NK cells during the IL-27 treatment phase reverses tumor eradication, suggesting an NK cell requirement for this sequential gene therapy-mediated tumor eradication. Both reversal of the administration sequence and coadministration of IL-12 and IL-27 impaired tumor eradication in 4T1 tumor-bearing mice. This IL-12-->IL-27 sequential gene therapy, via sequential administration of IL-12- and IL-27-encoding plasmid DNA into tumor-bearing mice through i.m. electroporation, provides a simple but effective approach for eliminating inaccessible residual tumors.

Electroporation-mediated IL-12 gene therapy in a transplantable canine cancer model

Interleukin-12 (IL-12) is effective in treating many types of rodent tumors, but has been unsuccessful in most human clinical trials, suggesting that animal models of more clinical relevance are required for evaluating human cancer immunotherapy. Herein, we report on the effectiveness of gene therapy with plasmid encoding human IL-12 (pIL-12) through in vivo electroporation in the treatment of beagles with a canine tumor, the canine transmissible venereal tumor (CTVT). The optimal electroporation conditions for gene transfer into CTVTs were tested by luciferase activity and determined to be a voltage of 200 V and duration of 50 msec, with the number of shocks set at 10 pulses, and the use of an electrode with 2 needles. Under these conditions, intratumoral administration of as little as 0.1 mg pIL-12 followed by electroporation significantly inhibited the growth of well-established tumors and eventually led to complete tumor regression. Furthermore, local pIL-12 treatment also induced a strong systemic effect that prevented new tumor growth and cured established tumors at distant locations. Intratumoral administration of pIL-12 greatly elevated the IL-12 level in the tumor masses, but produced only a trace amount in the serum. A high level of IFN-gamma mRNA was also detected in the treated tumor masses. pIL-12 gene therapy attracted significantly more lymphocytes infiltrating the tumors, including CD4(+) and CD8(+) T cells, and the surface expression of MHC I and MHC II molecules on CTVT cells was greatly increased after pIL-12 therapy. This treatment also induced apoptosis of the tumor cells as detected by Annexin V. More importantly, delivery of pIL-12 with intratumoral electroporation did not result in any detectable toxicity in the dogs. We conclude that intratumoral electroporation of the pIL-12 gene could cause profound immunologic host responses and efficiently treat CTVT in beagle dogs. The results also indicate that CTVT is an excellent large animal cancer model for testing immunogene therapies mediated by electroporation.

Transdermal Transport of India Ink by Electromagnetic Electroporation in Guinea Pigs: An Ultrastructural Study

Transdermic administration by electroporation has developed over recent years for applying drugs in a variety of pathological processes. However, mechanisms are still not finally settled. India ink was applied to the backs of guinea pigs and for the transdermic transport short, high-voltage pulses (TDES, Dencort Dell) were administrated. Punch biopsies (4 mm) immediately taken after 24, 48, 72, 96 and at 26 days were studied by light and electronic microscopy. The ultrastructural characteristics and image pigment particles were reported. Particles of India ink were observed in the stratum corneum and in the epidermic keratinocytes of samples studied immediately after treatment. Particles were also seen in the epidermic and folicular keratinocytes, and in the papillary and reticular dermis (among collagen fibers, vessel walls, and macrophages) in all the subsequent biopsies; but not in the controls, which were conducted with electromagnetic waves alone. No tissue alterations were observed. The efficacy and noninvasive nature of electroporation for the transdermic administration of macromolecules is confirmed.

Ups and downs: the STAT1:STAT3 seesaw of Interferon and gp130 receptor signalling

Downstream of cytokine or growth factor receptors, STAT3 counteracts inflammation and promotes cell survival/proliferation and immune tolerance while STAT1 inhibits proliferation and favours innate and adaptive immune responses. STAT1 and STAT3 activation are reciprocally regulated and perturbation in their balanced expression or phosphorylation levels may re-direct cytokine/growth factor signals from proliferative to apoptotic, or from inflammatory to anti-inflammatory. Here we review the functional canonical and non-canonical effects of STAT1/3 activation and discuss the hypothesis that perturbation of their expression and/or activation levels may provide novel therapeutic strategies in different clinical settings and particularly in cancer.

Doxorubicin Directs the Accumulation of Interleukin-12–Induced IFNγ into Tumors for Enhancing STAT1–Dependent Antitumor Effect

PURPOSE

To examine the mechanism by which doxorubicin plus interleukin-12 (IL-12) gene transfer induces enhanced therapeutic efficacy against tumors.

EXPERIMENTAL DESIGN

Tumor-bearing mice were treated with doxorubicin, IL-12-encoding plasmid DNA, doxorubicin plus IL-12-encoding plasmid DNA, or plasmid DNA control. Doxorubicin was systemically given via i.p. injection, and IL-12 was systemically expressed via i.m. injection. To show that doxorubicin enhances the accumulation of IL-12-induced IFN gamma into tumors and the signal transducer and activator of transcription 1 (Stat1)-dependent antitumor efficacy, the distribution of IFN gamma and the therapeutic end points, such as T-cell infiltration, inhibition of tumor vessel density, tumor growth inhibition, and inhibition of spontaneous tumor metastasis in wild-type and Stat1(-/-) host and tumors were determined after the treatment at the indicated time points.

RESULTS

In this study, a novel mechanism was unveiled. We discovered that doxorubicin enhances the accumulation of IL-12-induced IFN gamma in tumors. The doxorubicin-mediated accumulation of IFN gamma in tumors is caused by an increased accumulation of IFN gamma-secreting immune cells and not by a direct translocation of IFN gamma protein into tumors. Depletion of immune cells reverses the doxorubicin-mediated accumulation of IFN gamma into tumors and reverses the inhibition of tumor vessel density induced by coadministration of doxorubicin and IL-12 DNA. Knocking out IFN gamma signaling in the tumor host reverses the significant inhibition of tumor growth by coadministration of doxorubicin and IL-12.

CONCLUSIONS

The enhanced antitumor efficacy by coadministration of doxorubicin and IL-12 is dependent on the accumulation of IFN gamma in tumors. This discovery provides a possible strategy to reduce side effects caused by IL-12.

The mechanism of exogenous B7.1-enhanced IL-12-mediated complete regression of tumors by a single electroporation delivery

Electroporation-based mono-gene therapy has received great interest in recent years but coadministration of different therapeutic genes for treatment of tumors has not been well explored. We hypothesize that electroporation is capable of delivering multiple genes that induce an additive or synergistic antitumor effect. To test this hypothesis, we used mice that were bearing SCCVII or TRAMP tumors. Established tumors with a diameter of 4-5 mm were injected with control plasmid DNA or plasmid DNA encoding B7.1, IL-12 or both via electroporation. Tumor regression, CTL activity and the level of B7.1, IL-12 and Stat1 expression were determined in both wild-type mice and in mice with a knock-out of the Stat1 gene. Remarkably, a single coadministration of the plasmids that encoded IL-12 and B7.1 eradicated tumors in 80% of mice. The therapeutic effect was associated with high levels of endogenous B7.1 expression, activity of cytotoxic lymphocytes, and activation of Stat1. Both exogenous B7.1 and IL-12 were required for inducing a high level of Stat1 activation in tumors, which occurred through a mechanism that was independent of the host Stat1. Both stimulators were also required for inducing the strong cytotoxic lymphocyte activity and for increasing the level and extending the duration of endogenous B7.1 expression. We therefore propose a 2-signal stimulation model to explain the synergistic effect of the coadministration of IL-12 and B7.1 on the regression of the tumors.

Stat1 deficiency in the host enhances interleukin-12-mediated tumor regression

Signal transducer and activator of transcription 1 (Stat1) is considered a key transcription factor that inhibits tumorigenesis, and Stat1 activation in the host is required for interleukin-12 (IL-12)-mediated generation of CTL activity. Using syngeneic Stat1-/- C3H mice bearing SCCVII tumors in this study, we discovered opposite results. Stat1 deficiency in the host significantly enhances IL-12-mediated tumor regression, resulting in tumor eradication from 60% of SCCVII tumor-bearing mice and significant inhibition of tumor growth when compared with control treatment (P < 0.01). This effect is independent of both Stat1-activating cytokine IFN-gamma and Stat1-downstream effector molecule FasL because neither neutralization of IFN-gamma nor knocking out of FasL enhances or inhibits IL-12-mediated tumor regression. IL-12 induces a high intensity of tumor-specific CTL activity in Stat1-deficient mice (P < 0.01), increases the CD8 T-cell density in tumor bearing Stat1-/- mice, and induces a T-cell-dependent tumor regression. The increased CTL activity and the high-intensity infiltration of T cells into the tumors in IL-12-treated Stat1-/- mice are likely due to the longer survival than the same cells from wild-type mice. Together, the data show that inhibition of Stat1 expression in the host enhances tumor-local IL-12 gene therapy for regressing tumors. This conclusion provides a new concept for designing an effective treatment strategy.

Gamma interferon-inducible protein 10 induces HeLa cell apoptosis through a p53-dependent pathway initiated by suppression of human papillomavirus type 18 E6 and E7 expression

Gamma interferon-inducible protein 10 (IP10) is a member of the CXC family of chemokines. By differential mRNA display, we have demonstrated the upregulation of IP10 in coxsackievirus B3 (CVB3)-infected mouse hearts. Functional characterization of the IP10 gene in IP10-transfected Tet-On HeLa cells has found that IP10 induced cell apoptosis and inhibited viral replication. In the characterization of the IP10-induced apoptotic pathway, we found that overexpression of IP10 upregulated p53 and resulted in altered expression of p53-responsive genes such as the p21Cip1, p27kip1, NF-kappaB, Bax, and PUMA genes and the mitochondrial translocation of Bax. However, transduction of the IP10 cells with adenovirus expressing dominant negative p53 not only ablated p53-triggered gene expression but also abolished IP10-induced apoptosis and restored CVB3 replication to the control levels. These data suggest a novel mechanism by which IP10 inhibits viral replication through the induction of host cell death via a p53-mediated apoptotic pathway. We also found that constantly high-level expression of p53 in these tumor cells is attributed to the IP10-induced suppression of human papillomavirus E6 and E7 oncogene expression. Taken together, these data reveal not only a previously unrecognized link between chemokine IP10 and p53 in antiviral defense but also a mechanism by which IP10 inhibits tumor cell growth.