Prolonged Animal Survival Research Articles

Inhibition of Jumonji Histone Demethylases Selectively Suppresses HER2+ Breast Leptomeningeal Carcinomatosis Growth via Inhibition of GMCSF Expression.

HER2+ breast leptomeningeal carcinomatosis (HER2+ LC) occurs when tumor cells spread to cerebrospinal fluid-containing leptomeninges surrounding the brain and spinal cord, a complication with a dire prognosis. HER2+ LC remains incurable, with few treatment options. Currently, much effort is devoted toward development of therapies that target mutations. However, targeting epigenetic or transcriptional states of HER2+ LC tumors might efficiently target HER2+ LC growth via inhibition of oncogenic signaling; this approach remains promising but is less explored. To test this possibility, we established primary HER2+ LC (Lepto) cell lines from nodular HER2+ LC tissues. These lines are phenotypically CD326+CD49f-, confirming that they are derived from HER2+ LC tumors, and express surface CD44+CD24-, a cancer stem cell (CSC) phenotype. Like CSCs, Lepto lines showed greater drug resistance and more aggressive behavior compared with other HER2+ breast cancer lines in vitro and in vivo. Interestingly, the three Lepto lines overexpressed Jumonji domain-containing histone lysine demethylases KDM4A/4C. Treatment with JIB04, a selective inhibitor of Jumonji demethylases, or genetic loss of function of KDM4A/4C induced apoptosis and cell-cycle arrest and reduced Lepto cell viability, tumorsphere formation, regrowth, and invasion in vitro. JIB04 treatment of patient-derived xenograft mouse models in vivo reduced HER2+ LC tumor growth and prolonged animal survival. Mechanistically, KDM4A/4C inhibition downregulated GMCSF expression and prevented GMCSF-dependent Lepto cell proliferation. Collectively, these results establish KDM4A/4C as a viable therapeutic target in HER2+ LC and spotlight the benefits of targeting the tumorigenic transcriptional network. SIGNIFICANCE: HER2+ LC tumors overexpress KDM4A/4C and are sensitive to the Jumonji demethylase inhibitor JIB04, which reduces the viability of primary HER2+ LC cells and increases survival in mouse models.

Targeting autocrine amphiregulin robustly and reproducibly inhibits ovarian cancer in a syngeneic model: roles for wildtype p53

Ovarian cancer (OvCA) remains one of the most devastating malignancies, but treatment options are still limited. We report that amphiregulin (AREG) can serve as an effective and safe pharmacological target in a syngeneic murine model. AREG is highly abundant in abdominal fluids of patients with advanced OvCa. In immunocompetent animals, depletion or overexpression of AREG respectively prolonged or shortened animal survival. A new antibody we generated in AREG-knockout mice recognized murine AREG and reproducibly prolonged animal survival in the syngeneic model. The underlying mechanism likely involves binding of wildtype p53 to AREG’s promoter and autocrine activation of the epidermal growth factor receptor (EGFR), a step blocked by the antibody. Accordingly, depletion of p53 downregulated AREG secretion and conferred tolerance, whereas blocking an adaptive process involving CXCL1, which transactivates EGFR, might increase therapeutic efficacy. Consistent with these observations, analysis of OvCa patients revealed that high AREG correlates with poor prognosis of patients expressing wildtype TP53. In conclusion, clinical tests of the novel antibody are warranted; high AREG, normal TP53, and reduced CXCL1 activity might identify patients with OvCa who may derive therapeutic benefit.

Design of an Injectable Polypeptide Hydrogel Depot Containing the Immune Checkpoint Blocker Anti-PD-L1 and Doxorubicin to Enhance Antitumor Combination Therapy.

Combination therapy can be used to enhance the therapeutic response and decrease side effects during cancer treatment. In this study, a system is developed to locally deliver the immune checkpoint blockade antibody targeting programmed death-ligand 1 (anti-PD-L1 or aPD-L1) and doxorubicin (Dox), by an injectable, biocompatible polypeptide hydrogel as a drug depot. The localized and sustained release of Dox after the intratumoral injection of the co-loaded hydrogel induces immunogenic tumor cell death, thus promoting an antitumor immunological response. The tumor inhibitory effect is significantly enhanced by the simultaneous release of aPD-L1 at the tumor site thanks to its action on the inhibition of the PD-1/PD-L1 pathway and restoration of the tumor-killing effect of cytotoxic T cells. Treatment of the B16F10 melanoma model with the aPD-L1 and Dox co-loaded hydrogel leads to a remarkable inhibition of tumor progression and prolongation of animal survival.

Shape switching of CaCO3-templated nanorods into stiffness-adjustable nanocapsules to promote efficient drug delivery

Geometry and mechanical property have emerged as important parameters in designing nanocarriers, in addition to their size, surface charge, and hydrophilicity. However, inconsistent and even contradictory demands regarding the shape and stiffness of nanoparticles have been noted in blood circulation, tumor accumulation, and tumor cell internalization. Herein, CaCO3 nanorods (NRs) with an aspect ratio of around 2.4 are assembled with hyaluronic acid (HA) hydrogel layers to prepare CaCO3@HA NRs. The rod geometry enables lower recognition by macrophages and higher extravasation into tumor tissues than the spherical counterpart. In response to the slightly acidic tumor matrix, the acid-labile removal of CaCO3 templates achieves shape switching into spherical HA nanocapsules (NCs). The shape switchable CaCO3@HA NRs show significantly higher uptake and cytotoxicities to 4T1 cells than CaCO3-Si@HA NRs with silica layers on CaCO3 cores to inhibit shape switching. In addition, HA NCs with 2 − 8 layers of HA hydrogels exhibit stiffness from 1.85 to 12.3 N/m, and the assembly of 4 layers shows 2- to 3-fold higher cellular uptake than those of other NCs. The shape shift satisfies long-term blood circulation of NRs, and the resulting stiffness-adjustable NCs promote tissue infiltration and intracellular accommodation, resulting in a 4-fold higher drug accumulation in tumors. The CaCO3@HA NR treatment significantly suppresses tumor growth; prolongs animal survival; inhibits lung metastasis; and eliminates systemic toxicities to blood, liver, kidney, and heart tissues. This study achieves a comprehensive understanding of the shape and stiffness effects and demonstrates a hierarchical targeting strategy to address the multiple delivery barriers for chemotherapeutic agents. Statement of significanceThe different barriers involved in the drug delivery pathway have inconsistent and even contradictory demands on the shape and stiffness of nanoparticles. In the current study, in situ switching of nanorods (NRs) into spherical nanocapsules (NCs) in tumor tissues is proposed to address these dilemmas. The NR shape ensures long-term blood circulation and high tumor tissue accumulation, while the in situ switching into NCs promotes tissue infiltration and cellular internalization. NCs with different numbers of hydrogel layers also provide a robust system wherein NC stiffness is controlled as a single variable to study stiffness-dependent cellular behaviors. Thus, this straightforward design offers a comprehensive understanding of how the shape and stiffness of nanocarriers affect their biological pathways.

HER2-targeted antibody-drug conjugate induces host immunity against cancer stem cells

We previously tested HER2-targeted antibody-drug conjugates (ADCs) in immunocompromised (SCID) mice, precluding evaluation of host immunity, impact on cancer stem cells (CSCs), and potential benefit when combined with PD-L1 blockade. In this study, we tested HER2-targeted ADC in two immunocompetent mouse tumor models. HER2-targeted ADC specifically inhibited the growth of HER2-expressing tumors, prolonged animal survival, and reduced HER2+ and PD-L1+ cells. ADC+ anti-PD-L1 antibody augmented therapeutic efficacy, modulated immune gene signatures, increased the number and function of CD3+ and CD19+ tumor-infiltrating lymphocytes (TILs), induced tumor antigen-specific immunological memory, stimulated B cell activation, differentiation, and IgG1 production both systemically and in the tumor microenvironment. In addition, ADC therapy modulated Tcell subsets and their activation in TILs. Furthermore, HER2-targeted ADC reduced the number and tumorigenicity of ALDHhi CSCs. This study demonstrates that HER2-targeted ADC effectively targets ALDHhi CSCs and this effect is augmented by co-administration of anti-PD-L1 antibody.

Biomimetic Liposomal Nanoplatinum for Targeted Cancer Chemophototherapy.

Photodynamic therapy (PDT) of cancer is limited by tumor hypoxia. Platinum nanoparticles (nano‐Pt) as a catalase‐like nanoenzyme can enhance PDT through catalytic oxygen supply. However, the cytotoxic activity of nano‐Pt is not comprehensively considered in the existing methods to exert their multifunctional antitumor effects. Here, nano‐Pt are loaded into liposomes via reverse phase evaporation. The clinical photosensitizer verteporfin (VP) is loaded in the lipid bilayer to confer PDT activity. Murine macrophage cell membranes are hybridized into the liposomal membrane to confer biomimetic and targeting features. The resulting liposomal system, termed “nano‐Pt/VP@MLipo,” is investigated for chemophototherapy in vitro and in vivo in mouse tumor models. At the tumor site, oxygen produced by nano‐Pt catalyzation improves the VP‐mediated PDT, which in turn triggers the release of nano‐Pt via membrane permeabilization. The ultrasmall 3–5 nm nano‐Pt enables better penetration in tumors, which is also facilitated by the generated oxygen gas, for enhanced chemotherapy. Chemophototherapy with a single injection of nano‐Pt/VP@MLipo and light irradiation inhibits the growth of aggressive 4T1 tumors and their lung metastasis, and prolongs animal survival without overt toxicity.

Highly Efficient Water-Soluble Photosensitizer Based on Chlorin: Synthesis, Characterization, and Evaluation for Photodynamic Therapy.

The clinical applications of many photosensitizers (PSs) are limited because of their poor water solubility, weak tissue penetration, low chemical purity, and severe toxicity in the absence of light. We designed a novel chlorin-based PS (designated as HPS) to achieve fluorescence image-guided photodynamic therapy (PDT) with efficient ROS generation. In addition to its simple fabrication process, HPS has other advantages such as excellent water solubility, strong NIR absorption, and high biocompatibility upon chemical functionalization for enhanced phototherapy. HPS exhibited high photodynamic performance against lung cancer and breast cancer cells by generating a large amount of singlet oxygen (1O2) under 654 nm laser irradiation. HPS accumulated into multiple organelles such as mitochondria and the endoplasmic reticulum and triggered cell apoptosis by laser exposure. In the tumor-bearing mice, in vivo, HPS showed an optimal half-life in circulation and achieved fluorescence-image-guided PDT within the irradiation window, resulting in effective tumor growth inhibition and the prolonged survival of animals. Moreover, the antitumor PDT effect of HPS was close to the clinical trial phase II stage of HPPH even at the low dosage of 0.32 mg/kg (under 75 J/cm2 laser), while the systemic safety of HPS was much higher. In conclusion, HPS is a novel water-soluble chlorin derivative with excellent PDT potential for clinical transformation.

Modification of Extracellular Matrix Enhances Oncolytic Adenovirus Immunotherapy in Glioblastoma.

Extracellular matrix (ECM) component hyaluronan (HA) facilitates malignant phenotypes of glioblastoma (GBM), however, whether HA impacts response to GBM immunotherapies is not known. Herein, we investigated whether degradation of HA enhances oncolytic virus immunotherapy for GBM. Presence of HA was examined in patient and murine GBM. Hyaluronidase-expressing oncolytic adenovirus, ICOVIR17, and its parental virus, ICOVIR15, without transgene, were tested to determine if they increased animal survival and modulated the immune tumor microenvironment (TME) in orthotopic GBM. HA regulation of NF-κB signaling was examined in virus-infected murine macrophages. We combined ICOVIR17 with PD-1 checkpoint blockade and assessed efficacy and determined mechanistic contributions of tumor-infiltrating myeloid and T cells. Treatment of murine orthotopic GBM with ICOVIR17 increased tumor-infiltrating CD8+ T cells and macrophages, and upregulated PD-L1 on GBM cells and macrophages, leading to prolonged animal survival, compared with control virus ICOVIR15. High molecular weight HA inhibits adenovirus-induced NF-κB signaling in macrophages in vitro, linking HA degradation to macrophage activation. Combining ICOVIR17 with anti-PD-1 antibody further extended the survival of GBM-bearing mice, achieving long-term remission in some animals. Mechanistically, CD4+ T cells, CD8+ T cells, and macrophages all contributed to the combination therapy that induced tumor-associated proinflammatory macrophages and tumor-specific T-cell cytotoxicity locally and systemically. Our studies are the first to show that immune modulatory ICOVIR17 has a dual role of mediating degradation of HA within GBM ECM and subsequently modifying the immune landscape of the TME, and offers a mechanistic combination immunotherapy with PD-L1/PD-1 blockade that remodels innate and adaptive immune cells.

Therapy-Induced Transdifferentiation Promotes Glioma Growth Independent of EGFR Signaling.

EGFR is frequently amplified, mutated, and overexpressed in malignant gliomas. Yet the EGFR-targeted therapies have thus far produced only marginal clinical responses, and the underlying mechanism remains poorly understood. Using an inducible oncogenic EGFR-driven glioma mouse model system, our current study reveals that a small population of glioma cells can evade therapy-initiated apoptosis and potentiate relapse development by adopting a mesenchymal-like phenotypic state that no longer depends on oncogenic EGFR signaling. Transcriptome analyses of proximal and distal treatment responses identified TGFβ/YAP/Slug signaling cascade activation as a major regulatory mechanism that promotes therapy-induced glioma mesenchymal lineage transdifferentiation. Following anti-EGFR treatment, TGFβ secreted from stressed glioma cells acted to promote YAP nuclear translocation that stimulated upregulation of the pro-mesenchymal transcriptional factor SLUG and subsequent glioma lineage transdifferentiation toward a stable therapy-refractory state. Blockade of this adaptive response through suppression of TGFβ-mediated YAP activation significantly delayed anti-EGFR relapse and prolonged animal survival. Together, our findings shed new insight into EGFR-targeted therapy resistance and suggest that combinatorial therapies of targeting both EGFR and mechanisms underlying glioma lineage transdifferentiation could ultimately lead to deeper and more durable responses. SIGNIFICANCE: This study demonstrates that molecular reprogramming and lineage transdifferentiation underlie anti-EGFR therapy resistance and are clinically relevant to the development of new combinatorial targeting strategies against malignant gliomas with aberrant EGFR signaling.

Small Molecule-Based Prodrug Targeting Prostate Specific Membrane Antigen for the Treatment of Prostate Cancer.

Metastatic castration-resistant prostate cancer poses a serious clinical problem with poor outcomes and remains a deadly disease. New targeted treatment options are urgently needed. PSMA is highly expressed in prostate cancer and has been an attractive biomarker for the treatment of prostate cancer. In this study, we explored the feasibility of targeted delivery of an antimitotic drug, monomethyl auristatin E (MMAE), to tumor tissue using a small-molecule based PSMA lig-and. With the aid of Cy5.5, we found that a cleavable linker is vital for the antitumor activity of the ligand-drug conjugate and have developed a new PSMA-targeting prodrug, PSMA-1-VcMMAE. In in vitro studies, PSMA-1-VcMMAE was 48-fold more potent in killing PSMA-positive PC3pip cells than killing PSMA-negative PC3flu cells. In in vivo studies, PSMA-1-VcMMAE significantly inhibited tumor growth leading to prolonged animal survival in different animal models, including metastatic prostate cancer models. Compared to anti-PSMA antibody-MMAE conjugate (PSMA-ADC) and MMAE, PSMA-1-VcMMAE had over a 10-fold improved maximum tolerated dose, resulting in improved therapeutic index. The small molecule-drug conjugates reported here can be easily synthesized and are more cost efficient than anti-body-drug conjugates. The therapeutic profile of the PSMA-1-VcMMAE encourages further clin-ical development for the treatment of advanced prostate cancer.

Therapeutic targeting of transcriptional elongation in diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is associated with transcriptional dysregulation driven by H3K27 mutation. The super elongation complex (SEC) is required for transcriptional elongation through release of RNA polymerase II (Pol II). Inhibition of transcription elongation by SEC disruption can be an effective therapeutic strategy of H3K27M-mutant DIPG. Here, we tested the effect of pharmacological disruption of the SEC in H3K27M-mutant DIPG to advance understanding of the molecular mechanism and as a new therapeutic strategy for DIPG. Short hairpin RNAs (shRNAs) were used to suppress the expression of AF4/FMR2 4 (AFF4), a central SEC component, in H3K27M-mutant DIPG cells. A peptidomimetic lead compound KL-1 was used to disrupt a functional component of SEC. Cell viability assay, colony formation assay, and apoptosis assay were utilized to analyze the effects of KL-1 treatment. RNA- and ChIP-sequencing were used to determine the effects of KL-1 on gene expression and chromatin occupancy. We treated mice bearing H3K27M-mutant DIPG patient-derived xenografts (PDXs) with KL-1. Intracranial tumor growth was monitored by bioluminescence image and therapeutic response was evaluated by animal survival. Depletion of AFF4 significantly reduced the cell growth of H3K27M-mutant DIPG. KL-1 increased genome-wide Pol II occupancy and suppressed transcription involving multiple cellular processes that promote cell proliferation and differentiation of DIPG. KL-1 treatment suppressed DIPG cell growth, increased apoptosis, and prolonged animal survival with H3K27M-mutant DIPG PDXs. SEC disruption by KL-1 increased therapeutic benefit in vitro and in vivo, supporting a potential therapeutic activity of KL-1 in H3K27M-mutant DIPG.

COX-2 promotes mammary adipose tissue inflammation, local estrogen biosynthesis, and carcinogenesis in high-sugar/fat diet treated mice.

Obesity is a major risk factor for breast cancer, especially in post-menopausal women. In the breast tissue of obese women, cyclooxygenase-2 (COX-2)-dependent prostaglandin E2 (PGE2) production has been correlated with inflammation and local estrogen biosynthesis via aromatase. Using a mouse model of 7,12-dimethylbenz[a]anthracene/medroxyprogesterone-acetate (DMBA/MPA)-induced carcinogenesis, we demonstrated that an obesogenic diet promotes mammary tissue inflammation and local estrogen production, and accelerates mammary tumor formation in a COX-2-dependent manner. High-sugar/fat (HSF) diet augmented the levels of the pro-inflammatory mediators MCP-1, IL-6, COX-2, and PGE2 in mammary tissue, and this was accompanied by crown-like structures of breast (CLS-B) formation and aromatase/estrogen upregulation. Treatment with a COX-2 selective inhibitor, etoricoxib, decreased PGE2, IL-6, MCP-1, and CLS-B formation as well as reduced aromatase protein and estrogen levels in the mammary tissue of mice fed a HSF diet. Etoricoxib-treated mice showed increased latency and decreased incidence of mammary tumors, which resulted in prolonged animal survival when compared to HSF diet alone. Inhibition of tumor angiogenesis also seemed to account for the prolonged survival of COX-2 inhibitor-treated animals. In conclusion, obesogenic diet-induced COX-2 is sufficient to trigger inflammation, local estrogen biosynthesis, and mammary tumorigenesis.

Phenylboronic Ester -Modified Polymeric Nanoparticles for Promoting TRP2 Peptide Antigen Delivery in Cancer Immunotherapy

The tremendous development of peptide-based cancer vaccine has attracted incremental interest as a powerful approach in cancer management, prevention and treatment. As successful as tumor vaccine has been, major challenges associated with achieving efficient immune response against cancer are (1) drainage to and retention in lymph nodes; (2) uptake by dendritic cells (DCs); (3) activation of DCs. In order to overcome these barriers, here we construct PBE-modified TRP2 nanovaccine, which comprises TRP2 peptide tumor antigen and diblock copolymer PEG-b-PAsp grafted with phenylboronic ester (PBE). We confirmed that this TRP2 nanovaccine can be effectively trapped into lymph node, uptake by dendritic cells and induce DC maturation, relying on increased negative charge, ROS response and pH response. Consistently, this vehicle loaded with TRP2 peptide could boost the strongest T cell immune response against melanoma in vivo and potentiate antitumor efficacy both in tumor prevention and tumor treatment without any exogenous adjuvant. Furthermore, the TRP2 nanovaccine can suppress the tumor growth and prolong animal survival time, which may result from its synergistic effect of inhibiting tumor immunosuppression and increasing cytotoxic lymphocyte (CTL) response. Hence this type of PBE-modified nanovaccine would be widely used as a simple, safe and robust platform to deliver other antigen in cancer immunotherapy.

DIPG-03. THERAPEUTIC TARGETING OF TRANSCRIPTIONAL ELONGATION IN DIFFUSE INTRINSIC PONTINE GLIOMA

Diffuse intrinsic pontine glioma (DIPG) is highly aggressive brain stem tumor and needed to develop novel therapeutic agents for the treatment. The super elongation complex (SEC) is essential for transcription elongation through release of RNA polymerase II (Pol II). We found that AFF4, a scaffold protein of the SEC, is required for the growth of H3K27M-mutant DIPG cells. In addition, the small molecule SEC inhibitor, KL-1, increased promoter-proximal pausing of Pol II, and reduced transcription elongation, resulting in down-regulate cell cycle, transcription and DNA repair genes. KL-1 treatment decreased cell growth and increased apoptosis in H3K27M-mutant DIPG cells, and prolonged animal survival in our human H3K27M-mutant DIPG xenograft model. Our results demonstrate that the SEC disruption by KL-1 is a novel therapeutic strategy for H3K27M-mutant DIPG.

CD31/PECAM-1 impacts engraftment, growth and spread of mantle cell lymphoma cells and positively correlates with extramedullary involvement

Platelet/endothelial cell adhesion molecule 1 (PECAM-1, CD31) is an immunoglobulin superfamily member expressed on the surface of platelets, leukocytes and endothelial cells. The role of CD31 in biology of lymphomas has not yet been systemically studied. Expression of cell surface CD31 was analyzed by flow cytometry on primary MCL cells isolated from peripheral blood, bone marrow or malignant effusions obtained from 29 newly diagnosed MCL patients. CD31 was significantly more expressed in patients with documented extranodal involvement. Knock-down of CD31 expression in JEKO1 and MINO MCL cell lines hampered their subcutaneous engraftment in immunodeficient mice and prolonged overall survival of intravenously-xenografted animals. In contrast, transgenic overexpression of CD31 accelerated growth of subcutaneous JEKO1 and MINO tumors, shortened overall survival of intravenously-xenografted mice, and resulted in significantly increased frequency of extramedullary murine tissue infiltration Our observations suggest that CD31 facilitate survival and regulate extranodal spread of MCL cells.

Co-Administration of Fendiline Hydrochloride Enhances Chemotherapeutic Efficacy of Cisplatin in Neuroblastoma Treatment.

Despite significant improvement of neuroblastoma (NB) patients’ survival due to recent treatment advancements in recent years, NB is still associated with high mortality rate. In search of novel strategies to increase NB’s susceptibility to pharmacological treatments, we investigated the in vitro and in vivo effects of fendiline hydrochloride as an enhancer of cisplatin antitumor activity. To assess the modulation of fendiline treatment on cisplatin responses, we used in vitro (evaluating NB cell proliferation by XCELLigence technology and colony formation, and gene expression by RT-PCR) and in vivo (NB cell grafts in NOD-SCID mice) models of NB. NB cell treatment with fendiline induced the expression of the ncRNA NDM29, leading to cell differentiation and to the reduction of the expression of MDRs/ABC transporters linked to multidrug resistance. These events were correlated to higher NB cell susceptibility to cisplatin and, consequently, increased its cytotoxic potency. In vivo, this drug interaction causes an enhanced ability of cisplatin to induce apoptosis in NB masses, resulting in tumor growth reduction and prolonged animal survival rate. Thus, the administration of fendiline might be a possible novel therapeutic approach to increase cisplatin efficacy in aggressive and poorly responsive NB cases.

Successful 24-Hours Manufacture of Anti-CD19/CD22 Dual Chimeric Antigen Receptor (CAR) T Cell Therapy for B-Cell Acute Lymphoblastic Leukemia (B-ALL)

Introduction Multiple issues arise for a wider application of chimeric antigen receptor (CAR) T cell therapy including manufacturing time and antigen escape. Here we report data on an anti-CD19/CD22 dual CAR-T (GC022F) therapy based on a novel manufacturing platform, from a phase I clinical study (NCT04129099) in treating patients with B-cell acute lymphoblastic leukemia (B-ALL). Methods Peripheral blood (PB) mononuclear cells were obtained by leukapheresis. T-cells were separated and transduced with lentivirus that encodes a CD19/CD22 directed 4-1BB: ζ CAR. GC022F cells were manufactured using a novel FasTCARTM platform which takes 24 hours, while the conventional CD19/CD22 dual CAR-T (GC022C) cells used as parallel control in the preclinical study were manufactured by conventional process which typically takes 9-14 days. The phase I dose escalation study was initiated to explore the safety and efficacy of GC022F in patients with B-ALL. All patients received a conditioning regimen of IV fludarabine (25mg/m2/d) and cyclophosphamide (250mg/m2/d) for 3 days prior to GC022F infusion. Results When compared with the GC022C, GC022F cells showed 1) less exhaustion as indicated by lower percentage of PD-1+LAG3+ cells following co-culturing with tumor cells, 2) younger phenotypes as demonstrated by more abundant T central memory cells (Tcm; CCR7+CD45RA+ or CD45RO+CD62L+), 3) higher expansion fold at in vitro culture, and 4) high anti-leukemia efficacy in mice model (Fig.1). Comparing in vivo efficacy of GC022F with GC022C cells at lower doses, GC022F treatment were more potent and could reduce tumor burden earlier and faster, and led to significantly prolonged overall survival of the experimental animals. From Nov. 2019 to Jun. 2020, 9 children and 1 adult with B-ALL were enrolled and infused with GC022F, 2 in low-dose (6.0×104/kg), 7 in medium dose (1.0-1.5×105/kg), 1 in high-dose (2.25×105/kg). Patients' median observation time was 99 (14-210) days on the day of cut-off. Characteristics of enrolled patients are shown in Table 1. The median age was 10 (3-48) years, and the median bone marrow (BM) blasts were 21.0 (0.1-63.5) % at enrollment. Three patients had prior CD19 CAR-T cell therapy history and one of whom had prior allogeneic hematopoietic stem cell transplantation (allo-HSCT). After infusion, the median peak of circulating CAR-T cell copy number was 2.29 ×105 copies/µg genomic DNA (0.0014-5.66), which occurred around day 14 (day10 - day 28). Importantly, GC022F persisted well in PB with a median of 2.40×105 copies/µg genomic DNA (0.75-3.98) on day 28 in 5 of 9 patients with available 4 weeks of cellular kinetics data. GC022F exerted a superior safety profile with no observed grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity in all patients. Among those 6 patients with CRS, only 1 at high dose level had grade 2 CRS; only 1 developed grade 1 neurotoxicity. After GC022F infusion, 6/6 patients with BM blasts > 5% at enrollment achieved complete remission (CR) by day 28, 5/6 with minimal residual disease (MRD)-negative CR. For those 4 patients with MRD positive disease at enrollment, 3 became MRD-negative CR by day 28, 1 had persist MRD positive disease and withdrew from the study by 2 weeks. Five of 8 MRD-negative CR patients subsequently made a choice to pursue consolidation allo-HSCT with a median time interval of 57 (48-71) days post GC022F infusion and all have remained in MRD-negative CR except 1 died from graft-versus-host disease (GVHD) and infection 143 days post GC022F infusion. Of the other 3 patients without allo-HSCT, 2 relapsed with CD19+/CD22+ disease at 12-16 weeks follow-up, including the patient with prior history of CD19 CAR-T treatment and transplant. Conclusion This study demonstrated that anti-CD19/CD22 dual CAR T-cells could be successfully manufactured by FasTCARTM technology in 24 hours, with younger and less exhausted phenotypes. Moreover, the Dual FasTCAR-T cells showed more potent efficacy in xenograft mouse model compared to the conventional dual CAR-T cells. Our clinical data demonstrate that GC022F is safe and efficacious in treating patients with CD19+CD22+ B-ALL. More data on additional patients and longer observation time are needed to further evaluate CD19/CD22 dual FasTCAR-T cell product. Disclosures Cai: Gracell Biotechnologies Ltd: Current Employment. Wang:Gracell Biotechnologies Ltd: Current Employment. Chen:Gracell Biotechnologies Ltd: Current Employment. Ye:Gracell Biotechnologies Co., Ltd.: Current Employment. He:Gracell Biotechnologies Co., Ltd.: Current Employment. Cao:Gracell Biotechnologies Ltd: Current Employment. Sersch:Gracell Biotechnologies Co., Ltd.: Current Employment.

Functional imaging of RAS pathway targeting in malignant peripheral nerve sheath tumor cells and xenografts.

Malignant peripheral nerve sheath tumor (MPNST) is an aggressive form of soft-tissue sarcoma (STS) in children. Despite intensive therapy, relatively few children with metastatic and unresectable disease survive beyond three years. RAS pathway activation is common in MPNST, suggesting MEK pathway inhibition as a targeted therapy, but the impact on clinical outcome has been small to date. We conducted preclinical pharmacokinetic (PK) and pharmacodynamic studies of two MEK inhibitors, trametinib and selumetinib, in two MPNST models and analyzed tumors for intratumor drug levels. We then investigated 3'-deoxy-3'-[18 F]fluorothymidine (18 F-FLT) PET imaging followed by 18 F-FDG PET/CT imaging of MPNST xenografts coupled to short-term or longer-term treatment with selumetinib focusing on PET-based imaging as a biomarker of MEK inhibition. Trametinib decreased pERK expression in MPNST xenografts but did not prolong survival or decrease Ki67 expression. In contrast, selumetinib prolonged survival of animals bearing MPNST xenografts, and this correlated with decreased pERK and Ki67 staining. PK studies revealed a significantly higher fraction of unbound selumetinib within a responsive MPNST xenograft model. Thymidine uptake, assessed by 18 F-FLT PET/CT, positively correlated with Ki67 expression in different xenograft models and in response to selumetinib. The ability of MEK inhibitors to control MPNST growth cannot simply be predicted by serum drug levels or drug-induced changes in pERK expression. Tumor cell proliferation assessed by 18 F-FLT PET imaging might be useful as an early response marker to targeted therapies, including MEK inhibition, where a primary effect is cell-cycle arrest.

Cancer Immunotherapy via Targeting Cancer Stem Cells Using Vaccine Nanodiscs.

Cancer stem cells (CSCs) proliferate extensively and drive tumor metastasis and recurrence. CSCs have been identified in over 20 cancer types to date, but it remains unknown how to target and eliminate CSCs in vivo. Aldehyde dehydrogenase (ALDH) is a marker that has been used extensively for isolating CSCs. Here we present a novel approach to target and reduce the frequency of ALDHhigh CSCs by vaccination against ALDH. We have identified ALDH1-A1 and ALDH1-A3 epitopes from CSCs and developed synthetic high-density lipoprotein nanodiscs for vaccination against ALDHhigh CSCs. Nanodiscs increased antigen trafficking to lymph nodes and generated robust ALDH-specific T cell responses. Nanodisc vaccination against ALDHhigh CSCs combined with anti-PD-L1 therapy exerted potent antitumor efficacy and prolonged animal survival in multiple murine models. Overall, this is the first demonstration of a simple nanovaccine strategy against CSCs and may lead to new avenues for cancer immunotherapy against CSCs.

Tailored Chemodynamic Nanomedicine Improves Pancreatic Cancer Treatment via Controllable Damaging Neoplastic Cells and Reprogramming Tumor Microenvironment.

Pancreatic ductal adenocarcinoma (PDAC) strongly resists standard therapies since KRAS-mutated cancer cells harbor endogenous resistance toward chemotherapy-induced apoptosis and tumor-associated macrophages (TAMs) activate stroma cells to create the nearly impenetrable matrix. Herein, we developed a tailored nanocomplex through the self-assembly of synthetic 4-(phosphonooxy)phenyl-2,4-dinitrobenzenesulfonate and Fe3+ followed by hyaluronic acid decoration, realizing chemodynamic therapy (CDT) to combat PDAC. By controllably releasing its components in a GSH-sensitive manner under the distinctive redox homeostasis in cancer cells and TAMs, the nanocomplex selectively triggered a Fenton reaction to induce oxidative damage in cancer cells and simultaneously repolarized TAMs to deactivate stromal cells and thus attenuate stroma. Compared to gemcitabine, CDT remarkably inhibited tumor growth and prolonged animal survival in orthotopic PDAC models without noticeable side effects. This study provides a promising strategy to improve the treatment of PDAC through CDT-mediated controlled cancer cells damage and reprogramming of the stromal microenvironment.