Case Report: In Situ Vaccination by Autologous CD16+ Dendritic Cells and Anti-PD-L 1 Antibody Synergized With Radiotherapy To Boost T Cells-Mediated Antitumor Efficacy In A Psoriatic Patient With Cutaneous Squamous Cell Carcinoma

The combination of radiotherapy and immunotherapy improves the survival rate of patients with malignancies developed through escape from T-cell-mediated immune surveillance. Immune checkpoint inhibitors, such as anti-programmed cell death protein-ligand 1 (anti-PD-L1) antibody, are used to rescue exhausted T cells. Simultaneously, dendritic cells (DCs) which are antigen-presenting cells that can initiate T-cell activation, are used to induce a tumor-specific immune response. However, the synergistic antitumor efficacy of the aforementioned combinational immunotherapy with intratumoral injection of low-dose DCs has not been reported, and the underlying therapeutic mechanism requires further investigation. Herein, we present the special case of a psoriatic patient with cutaneous squamous cell carcinoma (cSCC) in the right inguinal region, these two diseases characterized by opposing contradiction, further complicating treatments and side-effect management efforts. To treat the intractable SCC without exaggerating psoriasis, we developed the triple-regimen therapy (TRT) with the intratumoral injection of low-dose autologous DCs and anti-PD-L1 combined with radiotherapy. The injected DCs were obtained simply through leukapheresis without prior G-CSF administration for mobilization nor tumor-antigen loading for expansion. The patient received three radiation doses (24, 18, and 18 Gy) combined with three intratumoral injections of anti-PD-L1 antibody (40, 60, and 120 mg) plus autologous DCs (80% of the DC subpopulation being CD16+ myeloid DC with approximate amounts of 7.3 × 104, 2.5 × 106, and 1.7 × 107) within 10 weeks. The efficacy of the TRT was encouraging in shrinking tumor mass with remarkable SUVmax reduction (approximately 42%) on FDG PET-Scan despite relatively low-dose DCs were available. The low-dose intratumoral immunotherapy induced mild cutaneous side effects as expected. The transcriptomes were compared between pre-TRT and post-TRT biopsies to analyze underlying mechanical pathways of the TRT protocol. Over 10 highly significantly enriched T-cell-related pathways (P <0.0001) were identified in post-TRT biopsies. In addition, the activation of both innate and adaptive immunity was significantly enriched in post-TRT peripheral blood samples. We develop the easily accessible TRT which produces both local anti-tumor T-cell responses and systemic antitumor immunity for treating cSCC patients, especially for those with autoimmune disease.

Identification of mitochondrial RNA polymerase as a potential therapeutic target of osteosarcoma

POLRMT (RNA polymerase mitochondrial) is essential for transcription of mitochondrial genome encoding components of oxidative phosphorylation process. The current study tested POLRMT expression and its potential function in osteosarcoma (OS). The Cancer Genome Atlas (TCGA) cohorts and Gene Expression Profiling Interactive Analysis (GEPIA) database both show that POLRMT transcripts are elevated in OS tissues. In addition, POLRMT mRNA and protein levels were upregulated in local OS tissues as well as in established and primary human OS cells. In different OS cells, shRNA-induced stable knockdown of POLRMT decreased cell viability, proliferation, migration, and invasion, whiling inducing apoptosis activation. CRISPR/Cas9-induced POLRMT knockout induced potent anti-OS cell activity as well. Conversely, in primary OS cells ectopic POLRMT overexpression accelerated cell proliferation and migration. In vivo, intratumoral injection of adeno-associated virus-packed POLRMT shRNA potently inhibited U2OS xenograft growth in nude mice. Importantly, levels of mitochondrial DNA, mitochondrial transcripts and expression of respiratory chain complex subunits were significantly decreased in U2OS xenografts with POLRMT shRNA virus injection. Together, POLRMT is overexpressed in human OS, promoting cell growth in vitro and in vivo. POLRMT could be a novel therapeutic target for OS.

Pseudomonas aeruginosa PcrV Enhances the Nitric Oxide-Mediated Tumoricidal Activity of Tumor-Associated Macrophages via a TLR4/PI3K/AKT/mTOR-Glycolysis-Nitric Oxide Circuit

Tumor-associated macrophages (TAMs), which display a tumor-supportive M2 phenotype, are closely related to tumor growth and metastasis. The reprogramming of TAMs toward a tumoricidal M1 profile has emerged as an attractive strategy for cancer immunotherapy. In this study, we found that the intratumoral injection of PcrV protein, a component of the Pseudomonas aeruginosa type 3 secretion system, suppressed tumor growth and increased apoptosis, inducible nitric oxide synthase (iNOS) expression, and the percentage of M1-polarized TAMs in tumor tissues. Furthermore, the intratumoral injection of PcrV-primed macrophages exerted a similar tumoricidal effect. In vitro analyses revealed that PcrV reeducated TAMs toward an antitumoral M1 phenotype and augmented their nitric oxide (NO)-mediated cytotoxicity against cancer cells. Mechanistically, we found that these effects were dependent on the activation of Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated regulation of a PI3K/AKT/mTOR-glycolysis-NO feedback loop via direct interaction with TLR4. Collectively, these results revealed a potential role for PcrV in cancer immunotherapy through the targeting of TAM plasticity.

Injectable Hydrogel for Synergetic Low Dose Radiotherapy, Chemodynamic Therapy and Photothermal Therapy

Higher doses of radiotherapy (RT) are associated with resistance induction, therefore highly selective and controllable radiosensitizers are urgently needed. To address this issue, we developed a FeGA-based injectable hydrogel system (FH) that can be used in combination with low-dose radiation. Our FH can deliver FeGA directly to the tumor site via intratumoral injection, where it is a reservoir-based system to conserve FeGA. The photothermal properties of FeGA steadily dissolve FH under laser irradiation, and, simultaneously, FeGA reacts with a large amount of H2O2 in the cell to produce OH (Fenton reaction) which is highly toxic to mitochondria, rendering the cell inactive and reducing radiotherapy resistance. In vivo and in vitro studies suggest that combining the FH and NIR irradiation with RT (2Gy) can significantly reduce tumor proliferation without side effects such as inflammation. To conclude, this is the first study to achieve combined chemodynamic therapy (CDT) and photothermal therapy (PTT) in situ treatment, and the best therapeutic effect can be obtained with a low-dose radiation combination, thus expanding the prospects of FeGA-based tumor therapy.

Advances in Injectable In Situ-Forming Hydrogels for Intratumoral Treatment

Chemotherapy has been linked to a variety of severe side effects, and the bioavailability of current chemotherapeutic agents is generally low, which decreases their effectiveness. Therefore, there is an ongoing effort to develop drug delivery systems to increase the bioavailability of these agents and minimize their side effects. Among these, intratumoral injections using in situ-forming hydrogels can improve drugs’ bioavailability and minimize drugs’ accumulation in non-target organs or tissues. This review describes different types of injectable in situ-forming hydrogels and their intratumoral injection for cancer treatment, after which we discuss the antitumor effects of intratumoral injection of drug-loaded hydrogels. This review concludes with perspectives on the future applicability of, and challenges for, the adoption of this drug delivery technology.

Visualizing CAR-T cell Immunotherapy Using 3 Tesla Fluorine-19 MRI

Purpose Chimeric antigen receptor (CAR) T cell cancer immunotherapies have shown remarkable results in patients with hematological malignancies and represent the first approved genetically modified cellular therapies. However, not all blood cancer patients respond favorably, serious side effects have been reported, and the treatment of solid tumors has been a challenge. An imaging tool for visualizing the variety of CAR-T cell products in use and being explored could provide important patient-specific data on CAR-T cell location to inform on potential success or failure of treatment as well as off-target toxicities. Fluorine-19 (19F) magnetic resonance imaging (MRI) allows for the noninvasive detection of 19F perfluorocarbon (PFC) labeled cells. Our objective was to visualize PFC-labeled (PFC +) CAR-T cells in a mouse model of leukemia using clinical field strength (3 Tesla) 19F MRI and compare the cytotoxicity of PFC + versus unlabeled CAR-T cells. Procedures NSG mice (n = 17) received subcutaneous injections of CD19 + human B cell leukemia cells (NALM6) expressing firefly luciferase in their left hind flank (1 × 106). Twenty-one days later, each mouse received an intratumoral injection of 10 × 106 PFC + CD19-targeted CAR-T cells (n = 6), unlabeled CD19-targeted CAR-T cells (n = 3), PFC + untransduced T cells (n = 5), or an equivalent volume of saline (n = 3). 19F MRI was performed on mice treated with PFC + CAR-T cells days 1, 3, and 7 post-treatment. Bioluminescence imaging (BLI) was performed on all mice days − 1, 5, 10, and 14 post-treatment to monitor tumor response. Results PFC + CAR-T cells were successfully detected in tumors using 19F MRI on days 1, 3, and 7 post-injection. In vivo BLI data revealed that mice treated with PFC + or PFC − CAR-T cells had significantly lower tumor burden by day 14 compared to untreated mice and mice treated with PFC + untransduced T cells (p < 0.05). Importantly, mice treated with PFC + CAR-T cells showed equivalent cytotoxicity compared to mice receiving PFC − CAR-T cells. Conclusions Our studies demonstrate that clinical field strength 19F MRI can be used to visualize PFC + CAR-T cells for up to 7 days post–intratumoral injection. Importantly, PFC labeling did not significantly affect in vivo CAR-T cell cytotoxicity. These imaging tools may have broad applications for tracking emerging CAR-T cell therapies in preclinical models and may eventually be useful for the detection of CAR-T cells in patients where localized injection of CAR-T cells is being pursued.

CTIM-20. FINAL RESULTS OF CONTROLLED IL-12 MONOTHERAPY AND IN COMBINATION WITH PD-1 INHIBITOR IN ADULT SUBJECTS WITH RECURRENT GLIOBLASTOMA

Ad-RTS-hIL-12(Ad) is a gene therapy candidate conditionally expressing IL-12 under the transcriptional control of veledimex(V) acting via the RheoSwitch Therapeutic System® gene switch. Veledimex plasma and tumor PK demonstrated a dose-response relationship and crossing the BBB. PD-1+ T-cells were increased in tumor biopsy samples after treatment with Controlled-IL-12 in a phase-l study. This finding was the rationale for conducting 2 trials of Controlled-IL-12 in combination with PD-1-inhibitor to enhance T-cell-mediated anti-tumor effects. Data from two completed phase-I studies (presented in SNO2020), and an ongoing phase-II study of Controlled-IL-12 with cemiplimab study for the treatment of recurrent glioblastoma (rGBM) will be discussed. Ziopharm has conducted 3 phase-I (NCT02026271/NCT03679754 (monotherapy), NCT03636477 (combination with nivolumab)) and one phase-ll (NCT04006119) multicenter, open-label, single-arm trial in subjects with rGBM is evaluating Ad (single intratumoral injection, 2 x 1011-viral-particles, Day0) with oral V dosing (20mg, Days 0-14) with cemiplimab infusions (350 mg IV) on Days -7, 15, then Q3W. Systemic biomarkers (serum cytokines, and immune-activation-markers), local effects (tumor cytokines, T-cell immunobiology, pathology), neoepitope, and imaging will be assessed. Subject characteristics (Controlled IL-12 monotherapy (n=75); combination (Controlled IL-12 with anti-PD-1s) (n=61) were consistent across all 3 studies. Safety profiles were comparable between monotherapy and in combination with anti-PD-1s. Adverse reactions (ARs) after nivolumab or cemiplimab were consistent with labeling of anti-PD-1s. ARs related to Controlled IL-12 were all manageable and reversible with no synergistic toxicities in combination with anti-PD-1s. Increases in serum cytokine levels and pathology findings consistent with immune-mediated anti-tumor effect were observed in subjects who received Controlled-IL-12 monotherapy and in combination with anti-PD-1s. Final survival data and results from neoepitope analysis will be presented. Further investigation is warranted to understand the impact of monotherapy vs. combination, concurrent steroids use and unifocal vs. multifocal disease on overall survival in subjects with rGBM receiving Controlled-IL-12.

TAMI-58. TARGETING GLIOBLASTOMA BY ACTIVATING VIRAL SPECIFIC TISSUE-RESIDENT MEMORY T CELLS

Immunotherapy with the success of checkpoint blockade brings hope for cancer treatment with enduring or complete responses in various types of advanced malignancies, however, it has not benefited a number of so called “cold tumors”, such as glioblastoma multiforme (GBM), the most common and aggressive adult brain cancer. GBM is invariably lethal with a median survival of less than 15 months and characterized by a highly immunosuppressive tumor microenvironment, which desires new means of GBM immune-reactivation. Tissue-resident memory CD8+ T (TRM) cells are non-recirculating memory T cell subpopulation that resides permanently in peripheral tissues. TRM cells provide long-lived protective immunity against not only local pathogen infection but also tumor development through immediate effector function and recruitment of circulating immune cells upon antigen re-exposure. In this study, we found that memory T cells specific to some common human viruses that have infected almost everybody exist in clinical GBM specimens and can be activated by viral peptides, which are MHC I restricted CD8+ T cell epitopes derived from those viruses. In orthotopic GBM immunocompetent mouse models, we detected abundant virus specific TRM cells in the tumor microenvironment of GBMs intracranially established in mice that were previously exposed to the virus. Excitingly, intratumoral injection of viral peptides stimulated the reactivation of TRM cells, indicated by secretion of immuno-stimulatory cytokines, and demonstrated significant anti-tumor efficacy. This study provides proof of principle for TRM cell-based GBM therapy, which is a novel therapeutic paradigm with the translational potential for this deadly malignancy.

496 Toxicity of an Fc engineered anti-CD40 antibody is abrogated by intratumoral injection and results in durable anti-tumor immunity in patients

BackgroundCurrently approved immune-based therapeutics primarily block inhibitory T cell checkpoints. Alternative approaches involve activation of immune pathways by agonism of stimulatory receptors, such as CD40. CD40 provides a central mechanism for the activation dendritic cells and is well established in pre-clinical models. Despite its promise, multiple clinical trials with agonistic anti-CD40 antibodies have reported minimal clinical responses and systemic toxicity. Efficient CD40 agonism requires receptor multimerization which we achieved by engineering the human anti-CD40 antibody CP-870,893 with 5 point-mutations in the Fc domain selectively increasing its binding to human FcyRIIB (herein ”2141-V11”). The re-engineered antibody demonstrated significantly enhanced anti-tumor activity as compared to its parental IgG2 version using a mouse model carrying human Fcy receptors (FcyR) and human CD40 (hFcyR/hCD40) in place of their mouse homologues.1 When given systemically, enhanced in vivo activity was accompanied by thrombocytopenia and transaminitis, similar toxicities seen with current clinical anti-CD40 antibodies, resulting from the expression of CD40 on platelets and Kupffer cell activation. As a prelude to clinical studies of 2141-V11 an optimized a dosing and delivery regimen resulting in minimal toxicity with optimal anti-tumor activity was developed, demonstrating that direct intratumoral injection led to potent local and systemic anti-tumor immunity.2MethodsWe performed pre-clinical toxicology testing in macaques and found no toxicity up to 100 mg/kg subcutaneously, in contrast to the toxicity observed in hCD40/hFcyR mice. CD40 agonistic antibodies require engagement by their Fc to FcyRIIB to achieve receptor multimerization and agonistic signaling. This lack of toxicity in macaques resulted from the observation that while 2141-V11 can engage the macaque CD40 molecule it does not engage the macaque inhibitory FcyRIIB, highlighting the importance of matching antibodies with their species specific Fc receptors. Full toxicology results will be reported at the annual meeting. We are now testing intratumoral 2141-V11 in a phase I clinical study using a 3+3 design in patients with solid tumors with injectable cutaneous, subcutaneous, or nodal lesions.ResultsWe have completed the first two cohorts without DLTs. In 5/6 patients with breast cancer the best overall response was stable disease. In one patient with melanoma in-transit disease we saw a complete response in the second dose group. The third dose group is currently enrolling and updated results will be reported at the meeting.Abstract 496 Figure 1Intratumoral 2141-V11 leads to both local and distant anti-tumor responses (melanoma)ConclusionsIntratumoral therapy with the Fc-enhanced CD40 agonist 2141-V11 has been demonstrated to be safe, with promising signs of early activity in both injected and distant non-injected lesions (figure 1).Trial RegistrationNCT04059588ReferencesDahan R, Barnhart BC, Li F, Yamniuk AP, Korman AJ, Ravetch JV. Therapeutic Activity of Agonistic, Human Anti-CD40 Monoclonal Antibodies Requires Selective FcγR Engagement. Cancer Cell 2016;0(0):3755–66.Knorr DA, Dahan R, Ravetch JV. Toxicity of an Fc-engineered anti-CD40 antibody is abrogated by intratumoral injection and results in durable antitumor immunity. Proceedings of the National Academy of Sciences 2018. Oct 23;115(43):11048–11053.Ethics ApprovalThis study was approved by the Rockefeller University IRB.