Alteration of the Tumor Stroma Using a Consensus DNA Vaccine Targeting Fibroblast Activation Protein (FAP) Synergizes with Antitumor Vaccine Therapy in Mice

Purpose: Fibroblast activation protein (FAP) is overexpressed in cancer-associated fibroblasts and is an interesting target for cancer immune therapy, with prior studies indicating a potential to affect the tumor stroma. Our aim was to extend this earlier work through the development of a novel FAP immunogen with improved capacity to break tolerance for use in combination with tumor antigen vaccines.Experimental Design: We used a synthetic consensus (SynCon) sequence approach to provide MHC class II help to support breaking of tolerance. We evaluated immune responses and antitumor activity of this novel FAP vaccine in preclinical studies, and correlated these findings to patient data.Results: This SynCon FAP DNA vaccine was capable of breaking tolerance and inducing both CD8⁺ and CD4⁺ immune responses. In genetically diverse, outbred mice, the SynCon FAP DNA vaccine was superior at breaking tolerance compared with a native mouse FAP immunogen. In several tumor models, the SynCon FAP DNA vaccine synergized with other tumor antigen-specific DNA vaccines to enhance antitumor immunity. Evaluation of the tumor microenvironment showed increased CD8⁺ T-cell infiltration and a decreased macrophage infiltration driven by FAP immunization. We extended this to patient data from The Cancer Genome Atlas, where we find high FAP expression correlates with high macrophage and low CD8⁺ T-cell infiltration.Conclusions: These results suggest that immune therapy targeting tumor antigens in combination with a microconsensus FAP vaccine provides two-fisted punch-inducing responses that target both the tumor microenvironment and tumor cells directly. Clin Cancer Res; 24(5); 1190-201. ©2018 AACR.

Synthetic DNA-Encoded Monoclonal Antibody Delivery of Anti-CTLA-4 Antibodies Induces Tumor Shrinkage In Vivo

Antibody-based immune therapies targeting the T-cell checkpoint molecules CTLA-4 and PD-1 have affected cancer therapy. However, this immune therapy requires complex manufacturing and frequent dosing, limiting the global use of this treatment. Here, we focused on the development of a DNA-encoded monoclonal antibody (DMAb) approach for delivery of anti-CTLA-4 monoclonal antibodies in vivo With this technology, engineered and formulated DMAb plasmids encoding IgG inserts were directly injected into muscle and delivered intracellularly by electroporation, leading to in vivo expression and secretion of the encoded IgG. DMAb expression from a single dose can continue for several months without the need for repeated administration. Delivery of an optimized DMAb encoding anti-mouse CTLA-4 IgG resulted in high serum levels of the antibody as well as tumor regression in Sa1N and CT26 tumor models. DNA-delivery of the anti-human CTLA-4 antibodies ipilimumab and tremelimumab in mice achieved potent peak levels of approximately 85 and 58 μg/mL, respectively. These DMAb exhibited prolonged expression, with maintenance of serum levels at or above 15 μg/mL for over a year. Anti-human CTLA-4 DMAbs produced in vivo bound to human CTLA-4 protein expressed on stimulated human peripheral blood mononuclear cells and induced T-cell activation in a functional assay ex vivo In summary, direct in vivo expression of DMAb encoding checkpoint inhibitors serves as a novel tool for immunotherapy that could significantly improve availability and provide broader access to such therapies.Significance: DNA-encoded monoclonal antibodies represent a novel technology for delivery and expression of immune checkpoint blockade antibodies, thus expanding patient access to, and possible clinical applications of, these therapies. Cancer Res; 78(22); 6363-70. ©2018 AACR.

Synergy of Immune Checkpoint Blockade with a Novel Synthetic Consensus DNA Vaccine Targeting TERT

Immune checkpoint blockade antibodies are setting a new standard of care for cancer patients. It is therefore important to assess any new immune-based therapies in the context of immune checkpoint blockade. Here, we evaluate the impact of combining a synthetic consensus TERT DNA vaccine that has improved capacity to break tolerance with immune checkpoint inhibitors. We observed that blockade of CTLA-4 or, to a lesser extent, PD-1 synergized with TERT vaccine, generating more robust anti-tumor activity compared to checkpoint alone or vaccine alone. Despite this anti-tumor synergy, none of these immune checkpoint therapies showed improvement in TERT antigen-specific immune responses in tumor-bearing mice. αCTLA-4 therapy enhanced the frequency of T-bet+/CD44+ effector CD8+ T cells within the tumor and decreased the frequency of regulatory T cells within the tumor, but not in peripheral blood. CTLA-4 blockade synergized more than Treg depletion with TERT DNA vaccine, suggesting that the effect of CTLA-4 blockade is more likely due to the expansion of effector T cells in the tumor rather than a reduction in the frequency of Tregs. These results suggest that immune checkpoint inhibitors function to alter the immune regulatory environment to synergize with DNA vaccines, rather than boosting antigen-specific responses at the site of vaccination.

A Designer Cross-reactive DNA Immunotherapeutic Vaccine that Targets Multiple MAGE-A Family Members Simultaneously for Cancer Therapy

PURPOSE

Cancer/testis antigens have emerged as attractive targets for cancer immunotherapy. Clinical studies have targeted MAGE-A3, a prototype antigen that is a member of the MAGE-A family of antigens, in melanoma and lung carcinoma. However, these studies have not yet had a significant impact due to poor CD8⁺ T-cell immunogenicity, platform toxicity, or perhaps limited target antigen availability. In this study, we develop an improved MAGE-A immunogen with cross-reactivity to multiple family members.

EXPERIMENTAL DESIGN

In this study, we analyzed MAGE-A expression in The Cancer Genome Atlas and observed that many patients express multiple MAGE-A isoforms, not limited to MAGE-A3, simultaneously in diverse tumors. On the basis of this, we designed an optimized consensus MAGE-A DNA vaccine capable of cross-reacting with many MAGE-A isoforms, and tested immunogenicity and antitumor activity of this vaccine in a relevant autochthonous melanoma model.

RESULTS

Immunization of this MAGE-A vaccine by electroporation in C57Bl/6 mice generated robust IFNγ and TNFα CD8⁺ T-cell responses as well as cytotoxic CD107a/IFNγ/T-bet triple-positive responses against multiple isoforms. Furthermore, this MAGE-A DNA immunogen generated a cross-reactive immune response in 14 of 15 genetically diverse, outbred mice. We tested the antitumor activity of this MAGE-A DNA vaccine in Tyr::CreER;BRAF^Ca/+;Pten^lox/lox transgenic mice that develop melanoma upon tamoxifen induction. The MAGE-A DNA therapeutic vaccine significantly slowed tumor growth and doubled median mouse survival.

CONCLUSIONS

These results support the clinical use of consensus MAGE-A immunogens with the capacity to target multiple MAGE-A family members to prevent tumor immune escape.

In vivo delivery of synthetic DNA-encoded antibodies induces broad HIV-1-neutralizing activity

Interventions to prevent HIV-1 infection and alternative tools in HIV cure therapy remain pressing goals. Recently, numerous broadly neutralizing HIV-1 monoclonal antibodies (bNAbs) have been developed that possess the characteristics necessary for potential prophylactic or therapeutic approaches. However, formulation complexities, especially for multiantibody deliveries, long infusion times, and production issues could limit the use of these bNAbs when deployed, globally affecting their potential application. Here, we describe an approach utilizing synthetic DNA-encoded monoclonal antibodies (dmAbs) for direct in vivo production of prespecified neutralizing activity. We designed 16 different bNAbs as dmAb cassettes and studied their activity in small and large animals. Sera from animals administered dmAbs neutralized multiple HIV-1 isolates with activity similar to that of their parental recombinant mAbs. Delivery of multiple dmAbs to a single animal led to increased neutralization breadth. Two dmAbs, PGDM1400 and PGT121, were advanced into nonhuman primates for study. High peak-circulating levels (between 6 and 34 μg/ml) of these dmAbs were measured, and the sera of all animals displayed broad neutralizing activity. The dmAb approach provides an important local delivery platform for the in vivo generation of HIV-1 bNAbs and for other infectious disease antibodies.

ZIP9 Is a Druggable Determinant of Sex Differences in Melanoma

Melanoma and most other cancers occur more frequently and have worse prognosis in males compared with females. Although sex steroids are thought to be involved, classical androgen and estrogen receptors are not detectable in most melanomas. Here we show that testosterone promotes melanoma proliferation by activating ZIP9 (SLC39A9), a zinc transporter that is widely expressed in human melanoma but not intentionally targeted by available therapeutics. This testosterone activity required an influx of zinc, activation of MAPK, and nuclear translocation of YAP. FDA-approved inhibitors of the classical androgen receptor also inhibited ZIP9, thereby antagonizing the protumorigenic effects of testosterone in melanoma. In male mice, androgen receptor inhibitors suppressed growth of ZIP9-expressing melanomas but had no effect on isogenic melanomas lacking ZIP9 or on melanomas in females. These data suggest that ZIP9 might be effectively targeted in melanoma and other cancers by repurposing androgen receptor inhibitors that are currently approved only for prostate cancer. SIGNIFICANCE: Testosterone signaling through ZIP9 mediates some of the sex differences in melanoma, and drugs that target AR can be repurposed to block ZIP9 and inhibit melanoma in males.

Abstract B113: Development of a novel synthetic consensus DNA vaccine that targets multiple MAGE-A family members for anticancer immune therapy

Cancer/testis (CT) antigens have emerged as attractive targets for cancer immune therapy due to their overexpression in tumor tissues and lack of expression in normal tissues. In particular, several clinical studies have been initiated to target the MAGE-A family of CT antigens for melanoma. These have included recombinant protein immunization and TCR-based gene therapy for MAGE-A3. The recombinant protein immunizations resulted in poor CD8+ T-cell responses and lack of efficacy thus far in the clinic. TCR-based gene therapy induced robust immune responses but unexpected toxicity. There is therefore a need to develop safe and effective therapies targeting the MAGE-A family of proteins for cancer therapy. In this study we performed a thorough analysis of MAGE-A RNA expression in The Cancer Genome Atlas (TCGA) and demonstrated that a high proportion of patients, in particular patients with melanoma and lung squamous cell carcinoma, exhibit expression of multiple MAGE-A family members simultaneously within the same tumor sample. Based on this information, we designed a consensus MAGE-A DNA vaccine that retains high homology (>85%) to multiple MAGE-A isoforms. Because mice and human MAGE-A family members are poorly conserved, we designed separate consensus constructs for testing in mice and in primates. Upon delivery of this mouse consensus MAGE-A vaccine intramuscularly followed by electroporation (EP) in C57Bl/6 mice, we detected robust IFN-γ and TNF-α CD8+ T-cell responses against multiple MAGE-A isoforms, including MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A5, MAGE-A6, and MAGE-A8 (p<0.005). Furthermore, we detected robust cytotoxic CD107a/IFN-γ/T-bet triple-positive CD8+ T cells in mice immunized with the consensus mouse MAGE-A vaccine. We evaluated the potency and cross-reactivity of this consensus mouse MAGE-A DNA vaccine in genetically diverse, outbred mice. We found that the majority of these mice (14/15) were capable of mounting a cross-reactive immune response and breaking tolerance to multiple MAGE-A isoforms simultaneously. We also demonstrated that this consensus mouse MAGE-A DNA vaccine is capable of slowing tumor growth in a therapeutic tumor challenge using the YUMM1.7 melanoma tumor model and the TC-1 lung tumor model. These results support the use of optimized MAGE-A consensus vaccines for cancer immune therapy.

Citation Format: Elizabeth K. Duperret, Aspen Trautz, Megan Paik, Charles Reed, Jian Yan, David B. Weiner. Development of a novel synthetic consensus DNA vaccine that targets multiple MAGE-A family members for anticancer immune therapy [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B113.

Abstract B036: Synthetic DNA-encoded monoclonal antibody delivery (DMAbTM) of anti-CTLA4 antibodies induces tumor shrinkage in vivo

Antibody-based immune therapies targeting the T-cell checkpoint inhibitors CTLA4 and PD1 have made incredible advances in cancer therapy. In particular, the combination of CTLA4 and PD1 blockade (using ipilimumab and nivolumab, respectively) was recently shown to be the most effective immune therapy for improving progression-free survival in advanced melanoma patients. However, this immune therapy combination strategy is extraordinarily expensive due to high manufacturing costs of monoclonal antibodies, with an estimated annual cost of almost one million dollars per patient. In this study, we focused on the development of a DNA-encoded monoclonal antibody (DMAbTM) approach for delivery of anti-CTLA4 monoclonal antibodies in vivo. With this technology, formulated DMAbTM plasmids are injected into the muscle with electroporation, allowing for muscle cells to produce and secrete the DMAbTM for a prolonged period of time without the need for repeated administration. In proof-of-concept studies in mice, we show that delivery of a DMAbTM plasmid for a monoclonal antibody targeting mouse CTLA4 (clone 9D9) elicits high serum expression (peak expression of 7.9µg/mL in immune-competent C57Bl/6 mice with one injection of DNA). This anti-mouse CTLA4 DMAbTM is capable of inducing tumor regression in A/J mice that were implanted with the immunogenic Sa1N tumor cell line without repeated administration. Furthermore, this anti-mouse CTLA4 DMAbTM is capable of synergizing with a DNA vaccine targeting the tumor antigen TERT in slowing tumor growth for the nonimmunogenic TC-1 tumor cell line. We also examined DNA delivery of the anti-human CTLA4 antibodies ipilimumab and tremelimumab. For these anti-human CTLA4 DMAbsTM, we achieved steady-state levels of approximately 75µg/mL and 50ug/mL for ipilimumab and tremelimumab, respectively, in mice, which is greater than the mean trough levels of ipilimumab achieved in patients (21.8µg/mL serum concentration for 3mg/kg dose). These anti-human CTLA4 DMAbsTM produced in vivo bind to human CTLA4 protein and induce T-cell activation in a functional assay ex vivo. These results demonstrate the feasibility of delivering immune checkpoint blockade monoclonal antibodies using DNA for cancer immune therapy. Future studies will explore combination therapies with CTLA4 DMAbsTM and chemotherapy.

Citation Format: Elizabeth Duperret, Aspen Trautz, Ami Patel, Joseph Kim, Kar Muthumani, David B. Weiner. Synthetic DNA-encoded monoclonal antibody delivery (DMAbTM) of anti-CTLA4 antibodies induces tumor shrinkage in vivo [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B036.

Kids These Days: Social Media's Influence on Adolescent Behaviors

We live in an electronic world with near-ubiquitous access to smartphones and social media. One consequence of this new reality is that children and teenagers may be unduly swayed by social media influencers who promote skincare products and practices, colloquially referred to as "skinfluencers," and enjoy unfettered access to emerging trends-not all of which lead to positive results. Herein, we describe two cases of adolescents presenting to a pediatric dermatology department after trying different beauty trends endorsed by social media influencers. The first patient developed allergic contact dermatitis to "snail slime" (96% Snail Secretion Filtrate; COSRX), a popular over-the-counter skincare product that has received notable attention on social media platforms due to its purported skin hydrating effects. The second patient presented urgently due to her mother's concerns of "overnight moles," which, in fact, the patient had acquired after applying makeup using a social media-endorsed "freckle stamp." Clinicians should be aware of these emerging trends to properly educate, manage, and treat patients susceptible to their influence-especially within the particularly impressionable teenage population.