576 Tumor Targeted Superantigen (TTS), Naptumomab Estafenatox (NAP), enhances CAR-T cells potency and can boost CAR-T efficacy against solid tumors

BackgroundCAR-T therapy has limited efficacy against solid tumors due to low trafficking to the tumor, limited cell expansion in patients, tumor antigen heterogeneity, and an immunosuppressive microenvironment. TTS are fusion proteins that consist of genetically engineered Superantigens (Sag) linked to Fragment antigen binding (Fab) moieties directed to tumor associated antigens. It was previously shown that TTS selectively activates a subset of T cells [1], turns ”cold tumors hot” [2] and, in preclinical models, can lead to long-term memory responses [3]. Here we present preclinical data demonstrating that the lead TTS compound, NAP (5T4 targeted Sag), enhanced the efficacy of CAR-T treatment against tumor cells in vitro, suggesting that NAP may overcome current CAR T limitations.MethodsHer2-CAR-T cells were produced in the presence of NAP or CD3&CD28, and their potency was evaluated against the FaDu cell line and by measurement of T cell activation markers (CD25, CD137, IFN-gamma, CD107a). The expression of memory markers (CCR7, CD45RA/CD45RO, CD95) and Th1 polarization (transcription factors) of the resulted CAR-T cells were analyzed by staining with specific antibodies. The combined potency of NAP with CAR-T was also tested in vitro against the FaDu cell line (which expresses both Her2 and 5T4 antigens). The chemotactic activity of T cells was assessed using a chemotactic chamber.ResultsPBMCs grown in the presence of NAP, in comparison with PBMCs grown in the presence of CD3&CD28 antibodies, resulted in the production of more potent CAR-T cells as measured both by killing assay using the FaDu cell line and by INFγ production, activation markers and T cell degranulation. Central memory (CM) percentages were increased and Th1 polarization was significantly more prominent after NAP stimulation. Following incubation with NAP, the chemotaxis towards the tumor cells was significantly enhanced. Finally, combination of CAR-T and NAP resulted in a synergistic killing effect of the tumor cell line.ConclusionsOur studies show that NAP generates more potent CAR-T cells and acts synergistically with CAR-T against tumor cell lines in vitro. The ability of NAP administration to activate T cells outside of the immunosuppressive microenvironment (in the lymphoid organs), promote T cell infiltration into the tumor and induce long-term memory responses, strongly suggests that combination of CAR-T cells with NAP may overcome the limited effect of CAR-T therapy against solid tumors. NAP is currently being evaluated in clinical studies in combination with durvalumab [NCT03983954] and docetaxel [NCT04880863].ReferencesHedlund G, Eriksson H, Sundstedt A, et al. The Tumor Targeted Superantigen ABR-217620 Selectively Engages TRBV7-9 and Exploits TCR-pMHC Affinity Mimicry in Mediating T Cell Cytotoxicity. PLoS One. 2013; 8(10): e79082.Azulay M, Lifshits S, Friedmann A, et al. Naptumomab Estafenatox induces T cell recognition, turning anti-PD-1 unresponsive “cold” tumors into “hot” responsive tumors. Cancer Research. Jul 2018, 78 (13 Supplement) abstract # 2712 AACR Annual Meeting 2018; Chicago, IL; DOI: 10.1158/1538-7445.AM2018-2712.Azulay M, Lifshits S, Shany E, et al. Selective T cell Redirection Proteins (STR) Enhance the Anti-Tumor Activity of Checkpoint Inhibitors (CPIs) and can Lead to Long-Lasting Immunity Against the Tumor. Abstract # P657. SITC 34th Annual Meeting, 2019. National Harbor, Maryland, USA.

3-MA Enhanced Chemosensitivity in Cisplatin Resistant Hypopharyngeal Squamous Carcinoma Cells via Inhibiting Beclin -1 Mediated Autophagy

Background: Hypopharyngeal carcinoma is characterized by high degree of malignancy. The most common pathological type is squamous cell carcinoma (HSCC). Cisplatin (cis-diamminedichloroplatinum, CDDP) is one of the most widely used chemotherapeutic drugs nowadays and cisplatin resistance is a major problem in current treatment strategies. Clinical researches have reported that high autophagy level often caused insensitivity to chemotherapy, a common phenomenon that greatly reduces therapeutic effect in cisplatin-resistant tumor cell lines. 3-methyladenine (3-MA), an inhibitor of PI3K, plays a vital role in the formation and development of autophagosomes. Therefore, we speculate that the use of 3-MA may reduce cisplatin resistance in hypopharyngeal squamous cell carcinoma (HSCC). Methods: Part I: Cisplatin-resistant FaDu cell line (Human hypopharyngeal squamous cell carcinoma cells) was established and cultured. Cell counting kit-8 was used to detect drug resistance. Inverted microscope was used to observe the morphological changes at different concentrations, then the survival rate was calculated. After MDC staining, the autophagic vacuoles were observed by fluorescence microscopy. The expression of Beclin1 from each group was confirmed by RTPCR and Western blot method. Part II: 3-MA was applied for cisplatin-resistant cells intervention, Beclin1 was knocked down by plasmid transfection. Cell cycle was detected using flow cytometry assay, apoptosis with necrosis was detected by staining with propidium iodide (PI). CCK-8 was used to observe the cell survival rate in each group. The expression of autophagy-related protein Beclin1, LC3I, LC3II, Atg-5 and P62 in each group was verified by Western blot analysis. Results: Cisplatin-resistant FaDu cell line can be stably constructed by cisplatin intervention. Compared with normal group, autophagy and its related protein Beclin1 expression was enhanced in cisplatin resistant FaDu cells. Autophagy inhibition group showed significant cell cycle changes, mainly manifested by G1 arrest, increased apoptosis rate and significantly decreased survival rate at 24h level. The number of autophagy vacuoles were significantly reduced in the 3-MA group. Furthermore, Western blot showed that expression of Beclin1, lc3-I, lc3-II, atg-5 protein decreased significantly after 3-MA intervention, while the expression of p62 up-regulated, which also confirmed autophagy flow was blocked. Conclusion: Our work confirmed that enhanced autophagy is an important cause of cisplatin resistance in FaDu cells. The use of 3-MA can significantly reduce autophagy level and arresting its cell cycle, promote apoptosis and reverse the cisplatin resistance condition, this effect is partly mediated by inhibition of Beclin-1 expression. Our data provides a theoretical basis for the application of 3-MA in overcoming cisplatin resistance in hypopharyngeal cancer.

Inhibition of autophagy enhanced chemosensitivity in cisplatin resistant hypopharyngeal squamous carcinoma cells

Background: Hypopharyngeal carcinoma is characterized by high degree of malignancy. The most common pathological type is squamous cell carcinoma (HSCC). It has been confirmed that high autophagy level promotes the development of hypopharyngeal cancer in recent years. Clinical researches have reported that high autophagy level often caused insensitivity to chemotherapy, a common phenomenon that greatly reduces therapeutic effect in cisplatin-resistant tumor cell lines. Therefore, exploring internal mechanisms of autophagy on cisplatin resistant HSCC is necessary for founding theoretical basis for synergistic antitumor drugs by interfering with autophagy.Methods: Part I: Cisplatin-resistant FaDu cell line was established and cultured. Cell counting kit-8 was used to detect drug resistance. Inverted microscope was used to observe the morphological changes at different concentrations, then the survival rate was calculated. After MDC staining, the autophagic vacuoles were observed by fluorescence microscopy. The expression of Beclin1 from each group was confirmed by RT-PCR and Western blot method. Part II: Beclin1 was knocked down by plasmid transfection, autophagy inhibitor 3-MA was applied for cisplatin-resistant cells intervention. Cell cycle was detected using flow cytometry assay, apoptosis with necrosis was detected by staining with propidium iodide (PI). CCK-8 was used to observe the cell survival rate in each group. The expression of autophagy-related gene Beclin1,LC3I,LC3II,Atg-5 and P62 in each group was verified by Western blot analysis.Results: Cisplatin-resistant FaDu cell line can be stably constructed by cisplatin intervention. Compared with normal group, autophagy and its related protein Beclin1 expression was enhanced in cisplatin resistant FaDu cells. Autophagy inhibition group showed significant cell cycle changes, mainly manifested by G1 arrest, increased apoptosis rate and significantly decreased survival rate at 24h level. Furthermore, Western blot showed that expression of Beclin1, lc3i, lc3ii, atg-5 protein decreased significantly after the inhibitor used, while the expression of p62 up-regulated, which also confirmed autophagy flow was blocked.Conclusion: Our work confirmed high autophagy level is important for the cisplatin-resistance of HSCC and insensitivity to chemotherapy. The use of 3-MA and Beclin 1 inhibition can significantly reduce autophagy level of cisplatin-resistant FaDu cells, arresting its cell cycle, promote apoptosis and reverse the multidrug resistance condition. These results provide the experimental basis for overcoming multidrug resistance through combination chemotherapy.#These authors contributed equally to this work.

Biomimetic Gold Nanoshell-Loaded Macrophage for Photothermal Biomedicine

The purpose of this study was to investigate the effect of photothermal treatment (PTT) with gold nanoshell (ANS) using a macrophage-mediated delivery system in a head and neck squamous cell carcinoma (HNSCC) cell line. To achieve this, ANS-loaded rat macrophages (ANS-MAs) were prepared via the coculture method with ANS. The human HNSCC (FaDu cell) and macrophage (rat macrophage; NR8383 cell) hybrid spheroid models were generated by the centrifugation method to determine the possibility of using ANS-MAs as a cancer therapy. These ANS-MAs were set into the tumor and macrophage hybrid spheroid model to measure PTT efficacy. Kinetic analysis of the spheroid growth pattern revealed that this PTT process caused a decreasing pattern in the volume of the hybrid model containing ANS-MAs (p<0.001). Comparison with empty macrophages showed harmony between ANS and laser irradiation for the generation of PTT. An annexin V/dead cell marker assay indicated that the PTT-treated hybrid model induced increasing apoptosis and dead cells. Further studies on the toxicity of ANS-MAs are needed to reveal whether it can be considered biocompatible. In summary, the ANS was prepared with a macrophage as the delivery method and protective carrier. The ANS was successfully localized to the macrophages, and their photoabsorption property was stationary. This strategy showed significant growth inhibition of the tumor and macrophage spheroid model under NIR laser irradiation. In vivo toxicology results suggest that ANS-MA is a promising candidate for a biocompatible strategy to overcome the limitations of fabricated nanomaterials. This ANS-MA delivery and PTT strategy may potentially lead to improvements in the quality of life of patients with HNSCC by providing a biocompatible, minimally invasive modality for cancer treatment.

Benzotriazine Di-Oxide Prodrugs for Exploiting Hypoxia and Low Extracellular pH in Tumors

Extracellular acidification is an important feature of tumor microenvironments but has yet to be successfully exploited in cancer therapy. The reversal of the pH gradient across the plasma membrane in cells that regulate intracellular pH (pHi) has potential to drive the selective uptake of weak acids at low extracellular pH (pHe). Here, we investigate the dual targeting of low pHe and hypoxia, another key feature of tumor microenvironments. We prepared eight bioreductive prodrugs based on the benzotriazine di-oxide (BTO) nucleus by appending alkanoic or aminoalkanoic acid sidechains. The BTO acids showed modest selectivity for both low pHe (pH 6.5 versus 7.4, ratios 2 to 5-fold) and anoxia (ratios 2 to 8-fold) in SiHa and FaDu cell cultures. Related neutral BTOs were not selective for acidosis, but had greater cytotoxic potency and hypoxic selectivity than the BTO acids. Investigation of the uptake and metabolism of representative BTO acids confirmed enhanced uptake at low pHe, but lower intracellular concentrations than expected for passive diffusion. Further, the modulation of intracellular reductase activity and competition by the cell-excluded electron acceptor WST-1 suggests that the majority of metabolic reductions of BTO acids occur at the cell surface, compromising the engagement of the resulting free radicals with intracellular targets. Thus, the present study provides support for designing bioreductive prodrugs that exploit pH-dependent partitioning, suggesting, however, that that the approach should be applied to prodrugs with obligate intracellular activation.

The Limitations of Collagen/CPP Hybrid Peptides as Carriers for Cancer Drugs to FaDu Cells

The in vitro efficacy of cancer prodrugs varies significantly between malignant cell lines. The most commonly identified problems relate to delivery: uptake mechanism, endosomal entrapment, and drug release. Here we present the study of collagen/cell penetrating hybrid (COL/CPP) peptide carriers intended to deliver paclitaxel to the hypopharyngeal carcinoma (FaDu) cells. Confocal microscopy imaging revealed the surprising response of FaDu cell to COL/CPP in comparison to previously studied cancer cell lines: hybrid peptides that carry both COL and CPP domain adsorb on the FaDu cell surface. While the CPP domain was design to facilitate the cellular uptake, in the case of FaDu cells, it also induced detrimental interactions with the cell membrane. Despite surface adsorption, the colocalization study with endosomal markers EEA1 and LAMP1 reveals that COL/CPP is internalized via endosomal pathway, peptides are able to escape before lysosome formation and release paclitaxel. Therefore, the main obstacle for paclitaxel delivery to FaDu cells appears to be related to cell surface properties. This behavior seems specific to FaDu cells, and could be linked to previously reported overexpression of T5, heparanase splice variants that produces protein lacking enzymatic activity of heparanase. This results in increased concentration of HSPG on FaDu cell surface, and possibly creates a barrier for cellular uptake of highly charged COL/CPP.