Antibodies targeting programmed cell death protein-1 (PD-1) or its ligand PD-L1 rescue T cells from exhausted status and revive immune response against cancer cells. Based on the immense success in clinical trials, ten α-PD-1 (nivolumab, pembrolizumab, cemiplimab, sintilimab, camrelizumab, toripalimab, tislelizumab, zimberelimab, prolgolimab, and dostarlimab) and three α-PD-L1 antibodies (atezolizumab, durvalumab, and avelumab) have been approved for various types of cancers. Nevertheless, the low response rate of α-PD-1/PD-L1 therapy remains to be resolved. For most cancer patients, PD-1/PD-L1 pathway is not the sole speed-limiting factor of antitumor immunity, and it is insufficient to motivate effective antitumor immune response by blocking PD-1/PD-L1 axis. It has been validated that some combination therapies, including α-PD-1/PD-L1 plus chemotherapy, radiotherapy, angiogenesis inhibitors, targeted therapy, other immune checkpoint inhibitors, agonists of the co-stimulatory molecule, stimulator of interferon genes agonists, fecal microbiota transplantation, epigenetic modulators, or metabolic modulators, have superior antitumor efficacies and higher response rates. Moreover, bifunctional or bispecific antibodies containing α-PD-1/PD-L1 moiety also elicited more potent antitumor activity. These combination strategies simultaneously boost multiple processes in cancer-immunity cycle, remove immunosuppressive brakes, and orchestrate an immunosupportive tumor microenvironment. In this review, we summarized the synergistic antitumor efficacies and mechanisms of α-PD-1/PD-L1 in combination with other therapies. Moreover, we focused on the advances of α-PD-1/PD-L1-based immunomodulatory strategies in clinical studies. Given the heterogeneity across patients and cancer types, individualized combination selection could improve the effects of α-PD-1/PD-L1-based immunomodulatory strategies and relieve treatment resistance. 

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Combination strategies with PD-1/PD-L1 blockade: current advances and future directions

https://molecular-cancer.biomedcentral.com/counter/pdf/10.1186/s12943-021-01489-2

Ovarian cancer is one of the most common malignant tumors in the female reproductive system with the highest mortality rate. Cul4B participates in the oncogenesis and progression of several malignant tumors. However, the role of Cul4B in ovarian cancer has not been studied. High expression of intratumor Cul4B was associated with poor patient survival. Cul4B expression was associated with FIGO stage and Cul4B was independent risk factor of ovarian cancer disease-free survival and overall survival. In vitro studies revealed that overexpression of Cul4B promoted tumor proliferation while knockdown of Cul4B significantly inhibited the proliferation capacity of ovarian cancer cells. Mechanistically, Cul4B was found to promotes cell entering S phase from G0/G1 phase by regulating the expression of CDK2 and CyclinD1. Cul4B regulates the expression of CDK2 and CyclinD1 by repressing miR-372. The results revealed that high expression of Cul4B is associated with poor ovarian cancer prognosis and Cul4B may serve as a potential treating target for an adjuvant therapy.

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Cul4B promotes the progression of ovarian cancer by upregulating the expression of CDK2 and CyclinD1

Abstract Emerging evidence indicates that the detection and clearance of cancer cells via phagocytosis induced by innate immune checkpoints play significant roles in tumor-mediated immune escape. The most well-described innate immune checkpoints are the “don’t eat me” signals, including the CD47/signal regulatory protein α axis (SIRPα), PD-1/PD-L1 axis, CD24/SIGLEC-10 axis, and MHC-I/LILRB1 axis. Molecules have been developed to block these pathways and enhance the phagocytic activity against tumors. Several clinical studies have investigated the safety and efficacy of CD47 blockades, either alone or in combination with existing therapy in hematological malignancies, including myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and lymphoma. However, only a minority of patients have significant responses to these treatments alone. Combining CD47 blockades with other treatment modalities are in clinical studies, with early results suggesting a synergistic therapeutic effect. Targeting macrophages with bispecific antibodies are being explored in blood cancer therapy. Furthermore, reprogramming of pro-tumor macrophages to anti-tumor macrophages, and CAR macrophages (CAR-M) demonstrate anti-tumor activities. In this review, we elucidated distinct types of macrophage-targeted strategies in hematological malignancies, from preclinical experiments to clinical trials, and outlined potential therapeutic approaches being developed. 

/pdf/targeting-macrophages-in-hematological-malignancies-recent-1smcatcl.pdf

Targeting macrophages in hematological malignancies: recent advances and future directions

Hypersialylation is a common post-translational modification of protein and lipids found on cancer cell surfaces, which participate in cell-cell interactions and in the regulation of immune responses. Sialic acids are a family of nine-carbon α-keto acids found at the outermost ends of glycans attached to cell surfaces. Given their locations on cell surfaces, tumor cells aberrantly overexpress sialic acids, which are recognized by Siglec receptors found on immune cells to mediate broad immunomodulatory signaling. Enhanced sialylation exposed on cancer cell surfaces is exemplified as “self-associated molecular pattern” (SAMP), which tricks Siglec receptors found on leukocytes to greatly down-regulate immune responsiveness, leading to tumor growth. In this review, we focused on all 15 human Siglecs (including Siglec XII), many of which still remain understudied. We also highlighted strategies that disrupt the course of Siglec-sialic acid interactions, such as antibody-based therapies and sialic acid mimetics leading to tumor cell depletion. Herein, we introduced the central roles of Siglecs in mediating pro-tumor immunity and discussed strategies that target these receptors, which could benefit improved cancer immunotherapy.

Siglecs as Therapeutic Targets in Cancer.

Most hepatocellular carcinoma (HCC) patients are diagnosed at an advanced stage; however, the effect of systemic therapy on advanced HCC remains undetermined. Therefore, new treatment targets must be identified. We analyzed Gene Expression Omnibus datasets from two HCC patient cohorts and found that NT5DC2 was associated with vascular invasion and poor survival. In two hepatoma cell lines, NT5DC2 overexpression promoted HCC cell proliferation and clone formation in vitro and promoted tumor growth in vivo. Coimmunoprecipitation assays and liquid chromatography with tandem mass spectrometry analysis revealed that NT5DC2 bound directly to epidermal growth factor receptor (EGFR). NT5DC2 upregulated EGFR expression by downregulating EGFR ubiquitination and preventing its degradation via the ubiquitin-proteasome pathway but did not upregulate its transcription. EGFR upregulation activated downstream signal transduction, which played a critical role in the protumor effects of NT5DC2. Erlotinib, a small-molecule inhibitor of EGFR, blocked the effect of NT5DC2 in promoting HCC cell proliferation. In a cohort of 79 patients who underwent curative resection for HCC, NT5DC2 expression in the tumors was associated with larger tumors and microvascular invasion. NT5DC2 expression was also independently associated with recurrence-free survival. The present study demonstrated for the first time that NT5DC2 promotes tumor cell proliferation in HCC and may serve as a potential molecular target for treating HCC. EGFR blockage could be used to treat selected patients with NT5DC2 upregulation.

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NT5DC2 promotes tumor cell proliferation by stabilizing EGFR in hepatocellular carcinoma.

Tumor-associated macrophages (TAMs) promote key processes in the modulation of tumor microenvironment (TME). However, the clinical significance of heterogeneous subpopulations of TAMs in hepatocellular carcinoma (HCC) remains unknown. HCC tissues from Zhongshan Hospital and data from The Cancer Genome Atlas were obtained and analyzed. Immunohistochemistry and flow cytometry were performed to detect the characteristics of sialic acid-binding immunoglobulin-like lectin 10high (Siglec-10hi) TAMs and explore their impact on the TME of HCC. The effect of Siglec-10 blockade was evaluated in vitro based on fresh human tumor tissues. Our data revealed that Siglec-10 was abundant in a large proportion of HCC specimens and prominently distributed on macrophages. Kaplan–Meier curves and Cox regression analysis showed that intratumoral Siglec-10+ cell enrichment was associated with unfavorable prognosis in patients with HCC. Notably, multiple anti-inflammatory cytokines and inhibitory receptors were enriched in Siglec-10hi TAMs. RNA sequencing data also revealed that numerous M2-like signaling pathways were significantly upregulated in Siglec-10hi TAMs. High infiltration of Siglec-10hi TAMs was associated with impaired CD8+ T cell function in HCC. Of note, blocking Siglec-10 with the competitive binding antibody Siglec-10 Fc led to decreased expression of immunosuppressive molecules and increased the cytotoxic effects of CD8+ T cells against HCC cells. Moreover, blocking Siglec-10 promoted the anti-tumor efficacy of the programmed cell death protein 1 (PD-1) inhibitor pembrolizumab. Siglec-10hi TAMs are associated with immune suppression in the TME, and indicate poor prognosis in patients with HCC. Targeting Siglec-10hi TAMs may serve as a promising immunotherapy approach for HCC.

/pdf/blocking-siglec-10hi-tumor-associated-macrophages-improves-2s9bu64ung.pdf

Blocking siglec-10hi tumor-associated macrophages improves anti-tumor immunity and enhances immunotherapy for hepatocellular carcinoma.

CD74 was initially thought to participate mainly in antigen presentation as an MHC class II chaperone. Recent studies have shown that CD74 plays an important role within the cell and throughout the immune system in a wide spectrum of neoplasms. However, the role of CD74 in hepatocellular carcinoma (HCC) remains elusive. In this study, HCC tissues from Zhongshan Hospital and data from The Cancer Genome Atlas (TCGA) were obtained and analyzed. Immunohistochemistry, flow cytometry, and single-cell RNA sequencing (scRNA-seq) were performed to detect the characteristics of CD74+ cells and explore their impact on the tumor microenvironment (TME) of HCC. Our data revealed that stromal CD74+ cell enrichment was associated with favorable prognosis in patients with HCC. CD74 was abundant in a large portion of HCC specimens and prominently distributed on stromal macrophages. scRNA-seq data also indicated that the pathways related to immune response were significantly upregulated in CD74+ macrophages. High infiltration of CD74+ macrophages was associated with increased infiltration of CD8+ cytotoxic T lymphocytes (CTLs) with enhanced effector functions in HCC. Besides, blocking CD74 weakened the antitumor activity and proliferation ability of CD8+ CTLs in HCC. Our findings highlight the critical role of CD74 in HCC. New drugs and antibodies targeting CD74 may be effective strategies for HCC therapy.

CD74+ macrophages are associated with favorable prognosis and immune contexture in hepatocellular carcinoma

A prospective study of the effect of terlipressin on portal vein pressure and clinical outcomes after hepatectomy: A pilot study.

Physical activity is known to have anti-cancer effects, including immunomodulatory actions. This study investigated the hypothesis that physical activity synergizes with combined lenvatinib plus anti-PD-1 therapy to enhance efficacy in patients with unresectable HCC.The physical activity levels of patients with unresectable HCC receiving combined lenvatinib plus anti-PD-1 therapy were recorded by questionnaire. Patients were categorized according to physical activity levels (active vs. sedentary). The primary outcome was overall survival (OS). Secondary outcomes included objective response rate (ORR) and progression-free survival (PFS). A subcutaneous syngeneic HCC model was generated in C57BL/6 mice. Mice were randomized to receive placebo, combined lenvatinib plus anti-PD-1 antibodies or combination therapy plus physical activity. Tumors were measured every 3 days and harvested for immunohistochemistry analysis at 20 mm maximum diameter.Fifty-nine patients with unresectable HCC were categorized to active (n = 28) or sedentary (n = 31) groups. The active group had higher albumin and des-γ-carboxy prothrombin levels and lower hepatitis B virus load at baseline; other clinical and oncologic characteristics were comparable between the two groups. Patients in the active group had significantly longer OS (HR = 0.220, 95% CI 0.060-0.799) and PFS (HR = 0.158, 95% CI 0.044-0.562) and higher ORR (OR = 4.571, 95% CI 1.482-14.102) than patients in the sedentary group. Regular physical activity was independently associated with OS, PFS and ORR. The mouse model showed that physical activity significantly suppressed tumor growth and prolonged survival of tumor-bearing mice. Furthermore, physical activity inhibited Treg cell infiltration and immune checkpoint expression (including CTLA4, TIGIT and TIM3) induced by long-term combined lenvatinib plus anti-PD-1 therapy, improving efficacy.Regular physical activity was associated with improved outcomes in unresectable HCC receiving combined lenvatinib plus anti-PD-1 therapy. Physical activity may improve therapeutic efficacy by reprograming the tumor microenvironment from an immunosuppressive to immunostimulatory phenotype. 

/pdf/physical-activity-improves-outcomes-of-combined-lenvatinib-jjnlp4pe.pdf

Physical activity improves outcomes of combined lenvatinib plus anti-PD-1 therapy in unresectable hepatocellular carcinoma: a retrospective study and mouse model

Nan Xiao

Papers

NT5DC2 promotes tumor cell proliferation by stabilizing EGFR in hepatocellular carcinoma.

Blocking siglec-10hi tumor-associated macrophages improves anti-tumor immunity and enhances immunotherapy for hepatocellular carcinoma.

CD74+ macrophages are associated with favorable prognosis and immune contexture in hepatocellular carcinoma

A prospective study of the effect of terlipressin on portal vein pressure and clinical outcomes after hepatectomy: A pilot study.

Physical activity improves outcomes of combined lenvatinib plus anti-PD-1 therapy in unresectable hepatocellular carcinoma: a retrospective study and mouse model