Noninvasive small-animal imaging of galectin-1 upregulation for predicting tumor resistance to radiotherapy

Highly specific GSH-triggered bifunctional molecules to enable precise imaging and targeted therapy of cancer

The utilization of diagnostic-integrated molecules can enable targeted delivery and controlled release to significantly enhance therapeutic effectiveness and minimize toxic effects. Herein, we developed a novel class of glutathione (GSH)-activated bifunctional molecules that respond to elevated levels of GSH in tumor microenvironment. These bifunctional molecules retained the pharmacodynamic effects of parent molecules and mitigated cytotoxicity. Meanwhile, controlled release was monitored using fluorescent signals, enabling detection of drug distribution and accumulation in situ and in real time. Moreover, the correlation between GSH levels and fluorescence intensity offers the possibility of monitoring the effectiveness of responsive drugs. In conclusion, bifunctional molecules, as novel diagnostic-integrated molecules with both fluorescence imaging and therapeutic effects, exhibited potential applications in cancer therapy and imaging.

Nanoprobe-based molecular imaging for tumor stratification

The responses of patients to tumor therapies vary due to tumor heterogeneity. Tumor stratification has been attracting increasing attention for accurately distinguishing between responders to treatment and non-responders. Nanoprobes with unique physical and chemical properties have great potential for patient stratification. This review begins by describing the features and design principles of nanoprobes that can visualize specific cell types and biomarkers and release inflammatory factors during or before tumor treatment. Then, we focus on the recent advancements in using nanoprobes to stratify various therapeutic modalities, including chemotherapy, radiotherapy (RT), photothermal therapy (PTT), photodynamic therapy (PDT), chemodynamic therapy (CDT), ferroptosis, and immunotherapy. The main challenges and perspectives of nanoprobes in cancer stratification are also discussed to facilitate probe development and clinical applications.

Noninvasive interrogation of CD8+ T cell effector function for monitoring tumor early responses to immunotherapy

Accurately identifying patients who respond to immunotherapy remains clinically challenging. A noninvasive method that can longitudinally capture information about immune cell function and assist in the early assessment of tumor responses is highly desirable for precision immunotherapy. Here, we show that PET imaging using a granzyme B–targeted radiotracer named ⁶⁸Ga-grazytracer, could noninvasively and effectively predict tumor responses to immune checkpoint inhibitors and adoptive T cell transfer therapy in multiple tumor models. ⁶⁸Ga-grazytracer was designed and selected from several radiotracers based on non-aldehyde peptidomimetics, and exhibited excellent in vivo metabolic stability and favorable targeting efficiency to granzyme B secreted by effector CD8⁺ T cells during immune responses. ⁶⁸Ga-grazytracer permitted more sensitive discrimination of responders and nonresponders than did ¹⁸F-fluorodeoxyglucose, distinguishing between tumor pseudoprogression and true progression upon immune checkpoint blockade therapy in mouse models with varying immunogenicity. In a preliminary clinical trial with 5 patients, no adverse events were observed after ⁶⁸Ga-grazytracer injection, and clinical responses in cancer patients undergoing immunotherapy were favorably correlated with ⁶⁸Ga-grazytracer PET results. These results highlight the potential of ⁶⁸Ga-grazytracer PET to enhance the clinical effectiveness of granzyme B secretion–related immunotherapies by supporting early response assessment and precise patient stratification in a noninvasive and longitudinal manner.

Galectin expression detected by 68Ga-galectracer PET as a predictive biomarker of radiotherapy resistance

PURPOSE

Hypoxia is a hallmark of solid tumors that is related to radiotherapy resistance. As galectin members, such as galectin-1 and galectin-3, are associated with tumor hypoxia, herein we aimed to investigate whether positron emission tomography (PET) imaging of galectin expression can be employed to effectively pinpoint tumor hypoxia, and to predict radiotherapy resistance.

METHODS

We synthesized a galectin-targeting radiotracer, designated ⁶⁸Ga-galectracer, by radiolabeling a thiodigalactoside derivative. The properties of ⁶⁸Ga-galectracer for PET imaging of tumor hypoxia were characterized in three tumor hypoxia mouse models. Additionally, preliminary PET/CT was performed in two patients with lung cancer to investigate the potential application of ⁶⁸Ga-galectracer for clinical imaging.

RESULTS

High-contrast imaging was achieved in the murine acute hypoxia tumor model, A549 natural hypoxia model, and sorafenib treatment-induced hypoxic 4T1 tumor model by PET using ⁶⁸Ga-galectracer. In fact, ⁶⁸Ga-galectracer exhibited superior hypoxia detection to that of ¹⁸F-misonidazole in the 4T1 tumors. Moreover, tumors with high galectin expression levels, as detected by ⁶⁸Ga-galectracer PET, exhibited significantly lower responses to subsequent radiotherapy compared to those with low galectin expression levels. In patients with lung cancer, PET imaging using ⁶⁸Ga-galectracer provided data that were complementary to that of the glucose metabolic PET radiotracer ¹⁸F-fluorodeoxyglucose.

CONCLUSION

⁶⁸Ga-galectracer is a promising radiotracer for PET-based imaging of tumor hypoxia in vivo. Thus, hypoxia PET with ⁶⁸Ga-galectracer could provide a noninvasive approach to proactively predict radiotherapy efficacy.

TRIAL REGISTRATION

Chictr.org.cn (ChiCTR2000029522). Registered 03 February 2020.

Unraveling How Tumor-Derived Galectins Contribute to Anti-Cancer Immunity Failure

Simple Summary

This review compiles our current knowledge of one of the main pathways activated by tumors to escape immune attack. Indeed, it integrates the current understanding of how tumor-derived circulating galectins affect the elicitation of effective anti-tumor immunity. It focuses on several relevant topics: which are the main galectins produced by tumors, how soluble galectins circulate throughout biological liquids (taking a body-settled gradient concentration into account), the conditions required for the galectins’ functions to be accomplished at the tumor and tumor-distant sites, and how the physicochemical properties of the microenvironment in each tissue determine their functions. These are no mere semantic definitions as they define which functions can be performed in said tissues instead. Finally, we discuss the promising future of galectins as targets in cancer immunotherapy and some outstanding questions in the field.

Abstract

Current data indicates that anti-tumor T cell-mediated immunity correlates with a better prognosis in cancer patients. However, it has widely been demonstrated that tumor cells negatively manage immune attack by activating several immune-suppressive mechanisms. It is, therefore, essential to fully understand how lymphocytes are activated in a tumor microenvironment and, above all, how to prevent these cells from becoming dysfunctional. Tumors produce galectins-1, -3, -7, -8, and -9 as one of the major molecular mechanisms to evade immune control of tumor development. These galectins impact different steps in the establishment of the anti-tumor immune responses. Here, we carry out a critical dissection on the mechanisms through which tumor-derived galectins can influence the production and the functionality of anti-tumor T lymphocytes. This knowledge may help us design more effective immunotherapies to treat human cancers.

Galectins in Cancer and the Microenvironment: Functional Roles, Therapeutic Developments, and Perspectives

Changes in cell growth and metabolism are affected by the surrounding environmental factors to adapt to the cell’s most appropriate growth model. However, abnormal cell metabolism is correlated with the occurrence of many diseases and is accompanied by changes in galectin (Gal) performance. Gals were found to be some of the master regulators of cell–cell interactions that reconstruct the microenvironment, and disordered expression of Gals is associated with multiple human metabolic-related diseases including cancer development. Cancer cells can interact with surrounding cells through Gals to create more suitable conditions that promote cancer cell aggressiveness. In this review, we organize the current understanding of Gals in a systematic way to dissect Gals’ effect on human disease, including how Gals’ dysregulated expression affects the tumor microenvironment’s metabolism and elucidating the mechanisms involved in Gal-mediated diseases. This information may shed light on a more precise understanding of how Gals regulate cell biology and facilitate the development of more effective therapeutic strategies for cancer treatment by targeting the Gal family.

State of the Art in Radiolabeling of Antibodies with Common and Uncommon Radiometals for Preclinical and Clinical Immuno-PET

Inert and stable radiolabeling of monoclonal antibodies (mAb), antibody fragments, or antibody mimetics with radiometals is a prerequisite for immuno-PET. While radiolabeling is preferably fast, mild, efficient, and reproducible, especially when applied for human use in a current Good Manufacturing Practice compliant way, it is crucial that the obtained radioimmunoconjugate is stable and shows preserved immunoreactivity and in vivo behavior. Radiometals and chelators have extensively been evaluated to come to the most ideal radiometal–chelator pair for each type of antibody derivative. Although PET imaging of antibodies is a relatively recent tool, applications with ⁸⁹Zr, ⁶⁴Cu, and ⁶⁸Ga have greatly increased in recent years, especially in the clinical setting, while other less common radionuclides such as ⁵²Mn, ⁸⁶Y, ⁶⁶Ga, and ⁴⁴Sc, but also ¹⁸F as in [¹⁸F]AlF are emerging promising candidates for the radiolabeling of antibodies. This review presents a state of the art overview of the practical aspects of radiolabeling of antibodies, ranging from fast kinetic affibodies and nanobodies to slow kinetic intact mAbs. Herein, we focus on the most common approach which consists of first modification of the antibody with a chelator, and after eventual storage of the premodified molecule, radiolabeling as a second step. Other approaches are possible but have been excluded from this review. The review includes recent and representative examples from the literature highlighting which radiometal–chelator–antibody combinations are the most successful for in vivo application.

Proteomic identification of tumor- and metastasis-associated galectin-1 in claudin-low breast cancer

BACKGROUND

Metastasis and mortality remain high among breast cancer patients with the claudin-low subtype because these tumors are aggressive, chemoresistant, and lack targeted therapies. Our objective was to utilize discovery-based proteomics to identify proteins associated with claudin-low primary and metastatic tumors to gain insight into pathways and mechanisms of tumor progression.

METHODS

We used nano-LC-MS/MS proteomics to analyze orthotopic and metastatic tumors from the syngeneic murine T11 tumor model, which displays gene expression profiles mirroring human claudin-low tumors. Galectin-1 identity, expression and spatial distribution were investigated by biochemical and immunochemical methods and MALDI/IMS. RNA seq data from mouse and human tumors in our study and publicly available microarray data were analyzed for differential galectin-1 expression across breast cancer subtypes.

RESULTS

Galectin-1, an N-acetyllactosamine-binding protein, exhibited the highest sequence coverage and high abundance rank order among nano-LC-MS/MS-identified proteins shared by T11 claudin-low tumors but not normal tissue. Label-free quantitation, Western immunoblot and ELISA confirmed galectin-1 identity and significant differential expression. MALDI/IMS spatial mapping and immunohistochemistry detected galectin-1 in T11 metastatic lung foci. Immunohistochemistry of human claudin-low tumors demonstrated intermediate-to-high intensity galectin-1 staining of tumor and stroma. Gene expression analysis of mouse and human tumors found the highest galectin-1 levels in the claudin-low breast cancer subtype.

CONCLUSIONS

Proteomics and genomics reveal high expression of galectin-1 protein and RNA in primary and metastatic claudin-low breast cancer.

GENERAL SIGNIFICANCE

This work endorses proteomic approaches in cancer research and supports further investigations of the function and significance of galectin-1 overexpression in claudin-low tumor progression.

Enhancing Anti-PD-1/PD-L1 Immune Checkpoint Inhibitory Cancer Therapy by CD276-Targeted Photodynamic Ablation of Tumor Cells and Tumor Vasculature

Antiangiogenic therapies have been demonstrated to improve the efficacy of immune checkpoint inhibition by overcoming the immunosuppressive status of the tumor microenvironment. However, most of the current antiangiogenic agents cannot discriminate tumor angiogenesis from physiological angiogenesis. The aim of this study was to investigate whether a photodynamic therapy (PDT) agent that targets CD276, a receptor overexpressed in various tumor cells and tumor vasculature but with limited expression in normal tissue vasculature, could improve the tumor inhibitory efficacy of a PD-1/PD-L1 blockade. A CD276-targeting agent (IRD-αCD276/Fab) was synthesized by conjugating the Fab fragment of an anti-CD276 antibody with a photosensitizer IRDye700. The in vivo tumor-targeting efficacy and therapeutic effects of IRD-αCD276/Fab with or without an anti-PD-1/PD-L1 blockade were tested in subcutaneous and lung metastatic tumor models. PDT using IRD-αCD276/Fab significantly suppressed the growth of subcutaneous 4T1 tumor and inhibited its lung metastasis. Moreover, it triggered in vivo antitumor immunity by increasing the activation and maturation of dendritic cells. Tumor PD-L1 levels were also markedly increased after PDT using IRD-αCD276/Fab, as evidenced by noninvasive PD-L1-targeted small-animal PET imaging. In combination with an anti-PD-1/PD-L1 blockade, IRD-αCD276/Fab PDT markedly suppressed the growth of tumors and prevented their metastasis to the lung by recruiting the tumor infiltration of CD8⁺ T cells. Our data provide evidence for the role of CD276-targeted PDT for local immune modulation, and its combination with PD-L1/PD-1 axis inhibition is a promising strategy for eliminating primary tumors as well as disseminated metastases, by generating local and systemic antitumor responses.

A tumor treatment strategy based on biodegradable BSA@ZIF-8 for simultaneously ablating tumors and inhibiting infection

Studies have shown a clear correlation between cancer incidence and infection, and cancer treatment can also trigger infection so as to lead to an inflammatory response. In this case, we have designed a new tumor treatment strategy based on biodegradable BSA@ZIF-8 for simultaneously ablating tumors and inhibiting infection. This biodegradable ZIF contains abundant porous structures, showing increased absorption of ions and inelastic collisions. A large amount of frictional heat produced by the collisions results in increased tumor cell death under microwave irradiation. This can effectively inhibit tumor growth in mice by microwave ablation with a good anti-tumor effect (95.4%). Intriguingly, the Zn²⁺ released from the degradation of BSA@ZIF-8 causes damage to bacterial cell walls, and destruction of the metabolism and structure of the membrane, leading to bacterial cell death, and ultimately achieving good antibacterial properties. Moreover, BSA@ZIF-8 is biodegradable without long-term toxicity in vivo. The in vivo experimental results show that BSA@ZIF-8 can protect 80% of the mice from lethal challenge with tumors and the accompanying infection. Overall, we present a novel strategy using biodegradable ZIFs for microwave ablation therapy with simultaneous antibacterial and anti-infection effects for the first time, which has achieved good tumor treatment outcomes.

Knockdown of galectin-1 facilitated cisplatin sensitivity by inhibiting autophagy in neuroblastoma cells

Neuroblastoma (NB) is a type of solid extracranial tumor that usually occurs in babies and children. Chemotherapy is a common method for NB treatment, however, the drug resistance exerts during the chemotherapy of NB. Galectin-1 is a member of galectin family and plays a potent role in the development of chemotherapy and radiotherapy resistance. However, the effect of galectin-1 on cisplatin resistance in NB remains unknown. The present study aimed to investigate the role of galectin-1 in cisplatin resisitance and the potential mechanism. Human neuroblastoma SH-SY5Y and SK-N-SH cells were treated with cisplatin and/or galectin-1/siRNA targeting galectin-1 (si-Gal-1). The cell viability was measured by MTT assay. The IC₅₀ values for cisplatin of neuroblastoma cells were calculated. The expression levels of autophagy markers including microtubule-associated protein light chain 3 (LC3B), Beclin-1, and p62 were detected by western blot. We found that cisplatin inhibited cell viability of SH-SY5Y and SK-N-SH in a dose-dependent manner. Cisplatin induced the ratio of LC3B-II/LC3B-I and Beclin-1 expression, and inhibited the p62 expression. Knockdown of galectin-1 decreased the IC₅₀ for cisplatin of SH-SY5Y and SK-N-SH cells and inhibited cisplatin-induced autophagy. Moreover, inhibition of autophagy suppressed galectin-1-induced increase in IC₅₀ for cisplatin. In conclusion, galectin-1 knockdown enhanced cisplatin sensitivity of neuroblastoma cells by inhibiting autophagy. The findings might provid a novel therapeutic target to overcome cisplatin resistance in chemotherapy of NB.

Controlling injectability and in vivo stability of thermogelling copolymers for delivery of yttrium-90 through intra-tumoral injection for potential brachytherapy

Intra-tumoral injection of radiopharmaceuticals such as yttrium-90 (⁹⁰Y) or phosphorus-32 (³²P) is an important route for brachytherapy in unresectable solid tumors such as locally advanced hepatocellular carcinoma. However, the injected radiopharmaceuticals can potentially leak out from the tumor site due to high intra-tumoral pressure. In this study, we demonstrated the use of thermogelling copolymers that can be injected into tumor and subsequently solidify as hydrogels within the tumor that can potentially overcome the above problem. To this end, a series of thermogelling polyurethane copolymers with varying compositions were designed and synthesized from Pluronic F127, poly(3-hydroxylbutyrate), and poly(propylene glycol), which were characterized in terms of their molecular structures, compositions, phase diagrams, rheological properties, and injectability and body temperature stability in vitro and in vivo. The analyses of our data elucidated the injectability of the copolymer solutions at low temperatures, and the stability of the hydrogels at the body temperature. This provided the basis on which we could identify one copolymer with balanced composition as the most suitable candidate for intra-tumoral injection and for prevention of the leakage. Finally, the injectability and in vivo stability of the copolymer solution and hydrogel loaded with ⁹⁰Y were further demonstrated in a mouse tumor model, and the in vivo biodistribution of ⁹⁰Y showed that the radionuclide could be retained at the tumor site, indicating that the ⁹⁰Y-loaded copolymer has a great potential for tumor radio-brachytherapy.