Evaluation of CD43 expression in non-hematopoietic malignancies

Targeting myeloid cells for cancer immunotherapy: Siglec-7/9/10/15 and their ligands

Advances in immunotherapy have revolutionized cancer treatment, yet many patients do not show clinical responses. While most immunotherapies target T cells, myeloid cells are the most abundant cell type in solid tumors and are key orchestrators of the immunosuppressive tumor microenvironment (TME), hampering effective T cell responses. Therefore, unraveling the immune suppressive pathways within myeloid cells could unveil new avenues for cancer immunotherapy. Over the past decade, Siglec receptors and their ligand, sialic acids, have emerged as a novel immune checkpoint on myeloid cells. In this review, we highlight key findings on how sialic acids modify immunity in the TME through engagement of Siglec-7/9/10/15 expressed on myeloid cells, and how the sialic acid-Siglec axis can be targeted for future cancer immunotherapies.

Targeting CD43 optimizes cancer immunotherapy through reinvigorating antitumor immune response in colorectal cancer

PURPOSE

Colorectal cancer (CRC) is one of the most common malignancies worldwide, with dramatically increasing incidence and mortality for decades. However, current therapeutic strategies for CRC, including chemotherapies and immunotherapies, have only demonstrated limited efficacy. Here, we report a novel immune molecule, CD43, that can regulate the tumor immune microenvironment (TIME) and serves as a promising target for CRC immunotherapy.

METHODS

The correlation of CD43 expression with CRC patient prognosis was revealed by public data analysis. CD43 knockout (KO) CRC cell lines were generated by CRISPR-Cas9 technology, and a syngenetic murine CRC model was established to investigate the in vivo function of CD43. The TIME was analyzed via immunohistochemical staining, flow cytometry and RNA-seq. Immune functions were investigated by depletion of immune subsets in vivo and T-cell functional assays in vitro, including T-cell priming, cytotoxicity, and chemotaxis experiments.

RESULTS

In this study, we found that high expression of CD43 was correlated with poor survival of CRC patients and the limited infiltration of CD8⁺ T cells in human CRC tissues. Importantly, CD43 expressed on tumor cells, rather than host cells, promoted tumor progression in a syngeneic tumor model. Loss of CD43 facilitated the infiltration of immune cells and immunological memory in the TIME of CRC tumors. Mechanistically, the protumor effect of CD43 depends on T cells, thereby attenuating T-cell-mediated cytotoxicity and cDC1-mediated antigen-specific T-cell activation. Moreover, targeting CD43 synergistically improved PD-L1 blockade immunotherapy for CRC.

CONCLUSION

Our findings revealed that targeting tumor-intrinsic CD43 could activate the antitumor immune response and provide particular value for optimized cancer immunotherapy by regulating the TIME in CRC patients.

Bispecific Antibodies Progression in Malignant Melanoma

The discovery of oncogenes and immune checkpoints has revolutionized the treatment of melanoma in the past 10 years. However, the current PD-L1 checkpoints lack specificity for tumors and target normal cells expressing PD-L1, thus reducing the efficacy on malignant melanoma and increasing the side effects. In addition, the treatment options for primary or secondary drug-resistant melanoma are limited. Bispecific antibodies bind tumor cells and immune cells by simultaneously targeting two antigens, enhancing the anti-tumor targeting effect and cytotoxicity and reducing drug-resistance in malignant melanoma, thus representing an emerging strategy to improve the clinical efficacy. This review focused on the treatment of malignant melanoma by bispecific antibodies and summarized the effective results of the experiments that have been conducted, also discussing the different aspects of these therapies. The role of the melanoma epitopes, immune cell activation, cell death and cytotoxicity induced by bispecific antibodies were evaluated in the clinical or preclinical stage, as these therapies appear to be the most suitable in the treatment of malignant melanoma.

Circular RNA hsa_circ_0000190 Facilitates the Tumorigenesis and Immune Evasion by Upregulating the Expression of Soluble PD-L1 in Non-Small-Cell Lung Cancer

Lung cancer is the leading cause of death from cancer in Taiwan and throughout the world. Immunotherapy has revealed promising and significant efficacy in NSCLC, through immune checkpoint inhibition by blocking programmed cell death protein (PD)-1/PD-1 ligand (PD-L1) signaling pathway to restore patients’ T-cell immunity. One novel type of long, non-coding RNAs, circular RNAs (circRNAs), are endogenous, stable, and widely expressed in tissues, saliva, blood, urine, and exosomes. Our previous results revealed that the plasma level of hsa_circ_0000190 can be monitored by liquid-biopsy-based droplet digital PCR and may serve as a valuable blood-based biomarker to monitor the disease progression and the efficacy of immunotherapy. In this study, hsa_circ_0000190 was shown to increase the PD-L1 mRNA-mediated soluble PD-L1 (sPD-L1) expression, consequently interfering with the efficacy of anti-PD-L1 antibody and T-cell activation, which may result in immunotherapy resistance and poor outcome. Our results unraveled that hsa_circ_0000190 facilitated the tumorigenesis and immune evasion of NSCLC by upregulating sPD-L1 expression, potentially developing a different aspect in elucidating the molecular immunopathogenesis of NSCLC. Hsa_circ_0000190 upregulation can be an effective indicator for the progression of NSCLC, and hsa_circ_0000190 downregulation may possess a potential therapeutic value for the treatment of NSCLC in combination with immunotherapy.

Myeloid Sarcoma Expressing Keratins and Mimicking Carcinoma-Case Report and Literature Review

Unusual presentations of otherwise common hematopoietic neoplasms are a well-recognized diagnostic challenge. Herein, we present a case study of a previously healthy 64 year old woman with myeloid sarcoma whose diagnosis was delayed by an unusual immunohistochemical staining pattern, including cytokeratin expression, by the neoplastic cells and by possible anchoring bias introduced by radiographic and flow cytometric immunophenotyping reports. This case study emphasizes the need to integrate clinical, radiographic, histologic, and immunophenotyping data for rapid and accurate tissue diagnoses while being wary of the lack of specificity for many common immunophenotypic markers.

Melanoma cells can be eliminated by sialylated CD43 × CD3 bispecific T cell engager formats in vitro and in vivo

Targeted cancer therapy with monoclonal antibodies has proven successful for different cancer types but is limited by the availability of suitable antibody targets. CD43s, a unique sialylated form of CD43 expressed by hematologic malignancies, is a recently identified target and antibodies interacting with CD43s may have therapeutic potential against acute myeloid leukemia (AML) and myelodysplastic syndrome. CD43s is recognized by the human antibody AT1413, that was derived from a high-risk AML patient who successfully cleared leukemia after allogeneic stem cell transplantation. Here we observed that AT1413 binds also to certain non-hematopoietic tumor cells, particularly melanoma and breast cancer. AT1413 immune precipitated CD43s from melanoma cells confirming that it recognizes the same target on melanoma as on AML. AT1413 induced antibody-dependent cellular cytotoxicity against short-term cultured patient-derived melanoma samples. However, AT1413 was unable to affect the growth of melanoma cells in vivo. To increase the efficacy of AT1413 as a therapeutic antibody, we generated two different formats of bispecific T-cell engaging antibodies (TCEs): one binding bivalently (bTCE) and the other monovalently (knob-in-hole; KiH) to both CD43s and CD3ε. In vitro, these TCEs redirected T-cell cytotoxicity against melanoma cells with differences in potencies. To investigate their effects in vivo, we grafted mice that harbor a human immune system with the melanoma cell line A375. Treatment with both AT1413 bTCE and AT1413 KiH significantly reduced tumor outgrowth in these mice. These data indicate a broad therapeutic potential of AT1413 that includes AML and CD43s-expressing solid tumors that originate from CD43-negative tissues.

Tumour-reactive B cells and antibody responses after allogeneic haematopoietic cell transplantation

For many high-risk haematologic malignancies, such as acute myeloid leukaemia, the success of therapy relies mainly on invoking a curative antitumour immune response. This can be achieved by inducing a graft-versus-leukaemia response following allogeneic haematopoietic cell transplantation. While the contribution of T cells and natural killer cells to graft-versus-leukaemia responses is established, the contribution of B cells and antibodies is relatively unexplored. This article reviews what is known about the contribution of B cells and tumour-specific antibody responses to a successful graft-versus-leukaemia response leading to eradication of the tumour.

Localization of Macrophages in the Human Lung via Design-based Stereology

Rationale: Interstitial macrophages (IMs) and airspace macrophages (AMs) play critical roles in lung homeostasis and host defense, and are central to the pathogenesis of a number of lung diseases. However, the absolute numbers of macrophages and the precise anatomic locations they occupy in the healthy human lung have not been quantified.Objectives: To determine the precise number and anatomic location of human pulmonary macrophages in nondiseased lungs and to quantify how this is altered in chronic cigarette smokers.Methods: Whole right upper lobes from 12 human donors without pulmonary disease (6 smokers and 6 nonsmokers) were evaluated using design-based stereology. CD206 (cluster of differentiation 206)-positive/CD43⁺ AMs and CD206⁺/CD43^- IMs were counted in five distinct anatomical locations using the optical disector probe.Measurements and Main Results: An average of 2.1 × 10⁹ IMs and 1.4 × 10⁹ AMs were estimated per right upper lobe. Of the AMs, 95% were contained in diffusing airspaces and 5% in airways. Of the IMs, 78% were located within the alveolar septa, 14% around small vessels, and 7% around the airways. The local density of IMs was greater in the alveolar septa than in the connective tissue surrounding the airways or vessels. The total number and density of IMs was 36% to 56% greater in the lungs of cigarette smokers versus nonsmokers.Conclusions: The precise locations occupied by pulmonary macrophages were defined in nondiseased human lungs from smokers and nonsmokers. IM density was greatest in the alveolar septa. Lungs from chronic smokers had increased IM numbers and overall density, supporting a role for IMs in smoking-related disease.