Building on the backbone of CD47-based therapy in cancer: Combination strategies, mechanisms, and future perspectives

EGFR Oncogenic Mutations in NSCLC Impair Macrophage Phagocytosis and Mediate Innate Immune Evasion Through Up-Regulation of CD47

INTRODUCTION

EGFR-mutated NSCLC is characterized by an immunosuppressive microenvironment that confers limited clinical effectiveness to anti-PD-1 or PD-L1 antibodies. Despite the discouraging outcomes of immunotherapy, novel immune checkpoints are constantly emerging, among which the specific vulnerability for therapeutic intervention in the context of EGFR-mutated NSCLC remains unresolved.

METHODS

Data sets of patient- and cell line-levels were used for screening and mutual validation of association between EGFR mutation and a panel of immune checkpoint-related genes. Regulatory mechanism was elucidated through in vitro manipulation of EGFR signaling pathway and evaluated by immunoblot analysis, quantitative polymerase chain reaction, flow cytometry, immunofluorescence staining, and chromatin immunoprecipitation. In vivo investigation of different therapeutic strategies were conducted using both immunocompetent and immunodeficient mouse models.

RESULTS

Among all screened immune checkpoints, CD47 emerged as the candidate most relevant to EGFR activation. Mechanistically, EGFR mutation constitutively activated downstream ERK and AKT pathways to respectively up-regulate the transcriptional factors c-Myc and NF-κB, both of which structurally bound to the promotor region of CD47 and actively transcribed this "don't eat me" signal. Impaired macrophage phagocytosis was observed on introduction of EGFR-sensitizing mutations in NSCLC cell line models, whereas CD47 blockade restored the phagocytic capacity and augmented tumor cell killing in both in vitro and in vivo models. Remarkably, the combination of anti-CD47 antibody with EGFR tyrosine kinase inhibitor revealed an additive antitumor activity compared with monotherapy of either antitumor agent in both immunocompetent and adaptive immunity-deficient mouse models.

CONCLUSIONS

EGFR-sensitizing mutation facilitates NSCLC's escape from innate immune attack through up-regulating CD47. Combination therapy incorporating CD47 blockade holds substantial promise for clinical translation in developing more effective therapeutic approaches against EGFR-mutant NSCLC.

Biomarker-driven molecular imaging probes in radiotherapy

Background: Biomarker-driven molecular imaging has emerged as an integral part of cancer precision radiotherapy. The use of molecular imaging probes, including nanoprobes, have been explored in radiotherapy imaging to precisely and noninvasively monitor spatiotemporal distribution of biomarkers, potentially revealing tumor-killing mechanisms and therapy-induced adverse effects during radiation treatment. Methods: We summarized literature reports from preclinical studies and clinical trials, which cover two main parts: 1) Clinically-investigated and emerging imaging biomarkers associated with radiotherapy, and 2) instrumental roles, functions, and activatable mechanisms of molecular imaging probes in the radiotherapy workflow. In addition, reflection and future perspectives are proposed. Results: Numerous imaging biomarkers have been continuously explored in decades, while few of them have been successfully validated for their correlation with radiotherapeutic outcomes and/or radiation-induced toxicities. Meanwhile, activatable molecular imaging probes towards the emerging biomarkers have exhibited to be promising in animal or small-scale human studies for precision radiotherapy. Conclusion: Biomarker-driven molecular imaging probes are essential for precision radiotherapy. Despite very inspiring preliminary results, validation of imaging biomarkers and rational design strategies of probes await robust and extensive investigations. Especially, the correlation between imaging biomarkers and radiotherapeutic outcomes/toxicities should be established through multi-center collaboration involving a large cohort of patients.

Improving nanochemoimmunotherapy efficacy by boosting "eat-me" signaling and downregulating "don't-eat-me" signaling with Ganoderma lucidum polysaccharide-based drug delivery

To address the challenges posed by low immunogenicity and immune checkpoints during cancer treatment, we propose an alternative strategy that combines immunogenic cell death (ICD) effects with CD47/SIRPα blockade to reactivate phagocytosis of tumor cells by macrophages with polysaccharide-based drug delivery. In this study, the EGFR inhibitor gefitinib was identified as a novel CD47 modulator, which promoted the translocation of CD47 molecules from the cell membrane to endosomes through the EGFR-Rab5 pathway, leading to reduced cell surface CD47 levels and limiting interaction with SIRPα. Based on this finding, we developed prophagocytic mixed nanodrugs to enhance macrophage phagocytosis by encapsulating ICD inducer doxorubicin and CD47 inhibitor gefitinib with immunostimulatory polysaccharides from Ganoderma lucidum. This approach downregulated cell surface CD47 expression to attenuate "don't-eat-me" signaling, while increasing doxorubicin accumulation in tumors by inhibiting drug-resistance proteins, leading to more exposure of calreticulin and amplifying the "eat-me" signaling. In vivo experiments demonstrated that this approach significantly suppressed intraperitoneal tumor dissemination, reversed doxorubicin-induced weight loss, and effectively induced macrophage polarization, dendritic cell maturation, and CD8+ T cell activation. These findings highlighted the significant potential of our macrophage-centered therapeutic strategy using polysaccharide-based nanocarriers and provided new perspectives for chemoimmunotherapy.

Tumor associated macrophages in esophageal squamous carcinoma: Promising therapeutic implications

Esophageal squamous carcinoma (ESCC) is a prevalent and highly lethal malignant tumor, with a five-year survival rate of approximately 20 %. Tumor-associated macrophages (TAMs) are the most prominent immune cells in the tumor microenvironment (TME), comprising over 50 % of the tumor volume. TAMs can be polarized into two distinct phenotypes, M1-type and M2-type, through interactions with cancer cells. M2-type TAMs are more abundant than M1-type TAMs in the TME, contributing to tumor progression, such as tumor cell survival and the construction of an immunosuppressive environment. This review focuses on the role of TAMs in ESCC, including their polarization, impact on tumor proliferation, angiogenesis, invasion, migration, therapy resistance, and immunosuppression. In addition, we discuss the potential of targeting TAMs for clinical therapy in ESCC. A thorough comprehension of the molecular biology about TAMs is essential for the development of innovative therapeutic strategies to treat ESCC.

Hydrogel-Based Therapeutics for Pancreatic Ductal Adenocarcinoma Treatment

Pancreatic ductal adenocarcinoma (PDAC), one of the deadliest malignancies worldwide, is characteristic of the tumor microenvironments (TME) comprising numerous fibroblasts and immunosuppressive cells. Conventional therapies for PDAC are often restricted by limited drug delivery efficiency, immunosuppressive TME, and adverse effects. Thus, effective and safe therapeutics are urgently required for PDAC treatment. In recent years, hydrogels, with their excellent biocompatibility, high drug load capacity, and sustainable release profiles, have been developed as effective drug-delivery systems, offering potential therapeutic options for PDAC. This review summarizes the distinctive features of the immunosuppressive TME of PDAC and discusses the application of hydrogel-based therapies in PDAC, with a focus on how these hydrogels remodel the TME and deliver different types of cargoes in a controlled manner. Furthermore, we also discuss potential drug candidates and the challenges and prospects for hydrogel-based therapeutics for PDAC. By providing a comprehensive overview of hydrogel-based therapeutics for PDAC treatment, this review seeks to serve as a reference for researchers and clinicians involved in developing therapeutic strategies targeting the PDAC microenvironment.

Targeted co-delivery of resiquimod and a SIRPα variant by liposomes to activate macrophage immune responses for tumor immunotherapy

Tumor-associated macrophages (TAMs) are the major immune cells infiltrating the tumor microenvironment (TME) and typically exhibit an immunosuppressive M2-like phenotype, which facilitates tumor growth and promotes resistance to immunotherapy. Additionally, tumor cells tend to express high levels of CD47, a "don't eat me" signal, that obstructs macrophage phagocytosis. Consequently, re-educating TAMs in combination with CD47 blockage is promising to trigger intense macrophage immune responses against tumors. As a toll-like receptor 7/8 agonist, resiquimod (R848) possesses the capacity to re-educate TAMs from M2 type to M1 type. We found that intratumoral administration of R848 synergistically improved the antitumor immunotherapeutic effect of CV1 protein (a SIRPα variant with high antagonism to CD47). However, the poor bioavailability and potential toxicity of this combo strategy remain a challenge. Here, a TAMs-targeted liposome (named: R-LS/M/CV1) co-delivering R848 and CV1 protein was constructed via decorating mannose on the liposomal surface. R-LS/M/CV1 exhibited high abilities of targeting, re-education and pro-phagocytosis of tumor cells to M2 macrophages in vitro. Intratumoral administration of R-LS/M/CV1 remarkedly eliminated tumor burden in the MC38 tumor model via repolarization of TAMs to M1 type, pro-phagocytosis of TAMs against tumors, and recruitment of tumor-infiltrating T cells. More encouragingly, due to the double targeting to TAMs and tumor cells of mannose and CV1 protein, R-LS/M/CV1 effectively accumulated at the tumor site, thereby not only remarkedly inhibiting tumors, but also exerting no hematological and histopathological toxicity when administered systemically. Our integrated strategy based on re-educating TAMs and CD47 blockade provides a promising approach to trigger macrophage immune responses against tumors for immunotherapy.